weaz4200

iTrader: (2)

i was wondering if someone can tell me how to calculate compression.... and what the ideal quench/squish is and ideal compression is? n also the formula of how to calculate what pistons (cc's) to use...what gasket thickness... what to deck the block to? i know i had the formula somewhere.. but now i cant find it.... i know it was something like.... 350 block, bored 0.030" with a 400 stroke crank will be .7854 X 4.030" X 4.030" X 3.750" times 16.387 to equal 783.84 cc's in the cylinder... n i use 64cc heads.... with the piston at top dead center even with deck(block decked to 0), so the piston deck height will be .7854 X 4.030" X 4.030" X 0.000" X 16.387 to equal 0 cc's in the piston deck height. pistons are d-cup with 18 cc's... n i use a head gasket with bore of 4.030" and compressed thickness of 0.040"....7854 X 4.030" X 4.030" X 0.040" X 16.387 = 8.36 cc's in the gasket.
Now add up all 5 of values. 783.84 + 64.00 + 0 + 18 + 8.36 = 874.2 cc's pushed in on the intake stroke with the intake valve open.
Now, we add up 4 of the values, leaving out cylinder volume. 64.00 + 0 + 18 + 8.36 = 90.36 cc's into which the mixture is compressed.
Now divide 874.2 by 90.36 to arrive at a 9.67 static compression ratio. does that sound right? n what is the difference between static and dynamic?

weaz4200

iTrader: (2)

actually... i found out one part off my question... someone said that a quench/squish of .039 - .042 is ideal.... so ill assume thats right...correct me if im wrong... but the bigger question is still... how do i know what compression ratio im shooting for?... n i think i've seen somewhere that id need different ratios if i went with iron heads v.s. aluminum... hope someone can clear this up...thanks...

gregsz-28

iTrader: (1)

I don't think this answers any of your questions, but it might save you some time:
http://www.csgnetwork.com/compcalc.html

weaz4200

iTrader: (2)

so with the values i put in.... using
Cylinder Bore Size (4.03)
Piston Stroke Length (3.75)
Head Gasket Bore Diameter (4.03)
Compressed Head Gasket Thickness (.040)
Combustion Chamber Volume In CCs (64cc)
Piston Dome Volume In CCs (18cc)
Piston Deck Clearance (0)
...it says my Calculated Engine Compression Ratio is 15.41930983195278 : 1
and Total Displacement Volume is 54.361054856131666 cc ...i dont get it... how would the calculator even know what block im using?

gregsz-28

iTrader: (1)

Your head gasket has a bigger bore than 4.030, it's probably 4.060 or 4.1.
It doesn't know what block you're using, but it does know the bore and stroke. The total displacement volume isn't your engines total CID, it is the combustion space, which is sure to be small with only 64 cc heads and 18 cc dome pistons.
Edit: I think the mistake you made was you put in to the calculator that you had dome pistons, but you really have dished pistons? That should put your CR near what you originally calculated.

Stekman

Aluminum heads dissipate heat faster than iron, so they can take higher compression ratios. Higher compression ratios yield hotter combustion temperatures. Aluminum, since it dissipates heat faster, needs a higher static compression to yield the same combustion temps as iron heads.

Assuming 92 octane, stay in the area of 9.5-10:1 for iron heads. Aluminum, 10.5:1 or so in the area is about what I put on engines for street use.

Static compression vs. dynamic compression. Static is merely a ratio of swept volume - displacement vs. the volume above the piston at TDC. In a nutshell, dynamic compression is the compression after the intake valve is fully closed. So where static compression is measured basically from BDC to TDC, dynamic compression replaces BDC with where the piston is when the intake valve fully closes.

weaz4200

iTrader: (2)

gregsz-28...FYI...these figures are hypothetical.... with the piston at TDC..right? so wouldnt that be 64cc + 18cc + 8.36 = 90.36? the pistons i used for reference are d-cup pistons with 18cc specs...Stekman... Static compression vs. dynamic compression....u lost me... let me see if i understand this... static is measured with the piston at TDC... n those figures include the pistons cc's/the piston at TDC (how many cc's from the top of the piston to the block deck height)/the cc's in the gasket/ and the cc's in the combustion chamber? im not following... elaborate please.... is there a formula for Dynamic compression? so with the figures i used... if 9.67 was my static compression ratio... how do i calculate the DC ratio? ...gregsz-28... got what u were talking about.... instead of using -18cc's with the calculator i used positive... made the adjustment an i indeed got a result of 9.67 : 1....

weaz4200

iTrader: (2)

Stekman... one other thing... u think u can explain when id need a higher compression v.s. a lower one...? i think somewhere ive seen something about where if i was running some sort of boost like turbo/supercharger/nitrous.... id need a different ratio as opposed to no boost...hope u get my question... thanks...

Apeiron

Engines with high cylinder pressures (like when you run forced induction) run into detonation problems at high compression ratios.

weaz4200

iTrader: (2)

u say high cylinder pressures.. like how high? so how do u know... (for example.. if hypothetically... i have.. like Stekman said a 10.5:1 CR n decide i want 13:1)... where u will start to reach detonation problems....is there a way to calculate when u would start to experience detonation problems? (with both forced induction and without)

gregsz-28

iTrader: (1)

We need to know your cam specs to calculate the dynamic compression ratio. Dynamic compression ratio is theoretically the reading you would get if you did a compression test on a completed engine.
Here is an online dynamic compression ratio calculator:
http://www.wallaceracing.com/dynamic-cr.php

chas0218

detonation is multiple sparks that happen at different times in the combustion chamber. Detonation can cause catastrophic engine failure if not addressed. Basically with anything 11:1 or larger compression ratio you will have detonation to some extent on cast iron heads. If you are running dished pistons you will be fine with a $30 set of advance auto/autozone head gaskets.

If your running domed pistons then your compression ratio will be 15.4:1 according to your numbers. With a DISHED piston your compression ratio will be 9.7:1.

Im running right under 10.5:1 on cast iron heads but only b/c i dont have the money for a set of new aluminum heads...

i used this site:
http://www.rbracing-rsr.com/compstaticcalc.html and these specs:

4.030" bore
3.75" stroke
.040" head gasket thickness
0" deck heigth
18cc Dish size in piston
64cc combustion chamber

.040" Head gasket is your average compressed size that you can buy at any parts store.

keep in mind with zero deck height you need to have .040" clearance between the head and piston.

Air_Adam

It depends on so many things... ambient air temp, fuel octane, fuel quality, fuel temp, combustion chamber design, piston design, camshaft profile, cylinder head temp, ignition timing/power, etc etc...

There are any number of things that can change whether ot not your combo will have detonation issues or not, even at different times in the same day... all you can really do is get a general idea and run off that.

Generally, you want your dynamic compression ratio to be between 8:1 and 9:1 if you are going to use it on pump gas. This might only require 9.5:1 static compression with a small cam, or maybe 12:1 with a fairly large cam.

weaz4200

iTrader: (2)

We need to know your cam specs to calculate the dynamic compression ratio. gregsz-28..... was using those parts for reference.... i do have one question about cams... n a lot of people have said to just talk with the cam maker and ask them... but i actually wanted to know how to go about selecting a cam... without having to call and ask them..... basically what and/or how do i decide on a cam? what numbers do i need to look at? lets take an example....comp cams 08-430-8 280HR ( http://www.compcams.com/Cam_Specs/Ca...?csid=180&sb=2 ) v.s. comp cams 08-432-8 XR282HR ( http://www.compcams.com/Cam_Specs/Ca...?csid=189&sb=2 ) which one of these 2 is better... or better yet what kind of results and/or performance would i get out of the 280HR v.s. the XR282HR? n be detailed with response please...one other important question ive been curious about.... u guys refer to the cams as small or large.... what spec's will dictate whether a cam is small or large and by looking at specs how do i know which cam is overkill or not enough for whatever application i build.... chas0218 and Air_Adam.. thanks for the info.... i appreciate it.... u guys can chime in as well about my cam questions... ill have some more questions soon... i think these are good for now...

gregsz-28

iTrader: (1)

Should I assume you have a roller 350 block? Because I don't think a lot of people put 3.75" stroke cranks in those. If not, you'll need a VERY expensive set of lifters to use a roller cam.
There is nothing that defines a cam as small or large, that is mostly a matter of opinion.

Stekman

I put 2 3.75" stroke cranks in 2 roller blocks last week.

New question: what is it you're exactly trying to accomplish by asking the various questions?

If you're doing a build, you pick a cam after you pick every single other component of the engine.

weaz4200

iTrader: (2)

i think thats what it is..... why is that? there are 2 answers to that question.... 1.... just pickin up knowledge... kinda got into the whole car scene not that long ago.... n i think i might wanna make it a career..... 2.... i am a detail oriented person... so even though i wont be building the engine soon... i like to have a list of what i need... so as i could check n recheck it again... so that i dont buy something down the line and think... man i should of researched it a lot more... n i could have got this instead of this... catch my drift? If you're doing a build, you pick a cam after you pick every single other component of the engine. i could do that.. but i want to be able to get combinations down so that i could decide what it is that i want exactly... im looking at building a 383 stroker....n yeah.. many will say i can purchase built ones.... but thats not what this is about... i want the experience... even if that means draining my wallet a little more..... and im looking to get around 500+ HP... hope that kinda clears things up..... so like i said... i wanna get a list n see what will get me to this goal... n for example..... this manifold v.s. that manifold will get me this result... or with these parts v.s. those parts... i will get this result... just to get some pros and cons of what will work for my application....

chas0218

technically if you are talking about the cam itself it can be a large or small base circle cam but in the way people are talking im guessing that they mean lift.

Stekman

Plenty of people build 383's with roller blocks.

First you decide what you want out of the engine. You stated 500+hp. Now how much are you willing to spend? This includes the rest of the drivetrain to be able to stand up to 500+. Transmission, rear end, the works. 500+ is useless if the transmission can only take 300 or so. Usually it works out to be an equal amount invested in the engine as the drivetrain.

Do some searches. See what other people are doing as far as powerful 383's. The way they got to their power level is going to end up being the same way you'd get to that power level.

As for a large cam or not, yes, matter of opinion, but really it's all relative. To a stock head, 230° duration @ .050" is a ton. To an 18° headed, 13:1 compression race motor, it's puny.

weaz4200

iTrader: (2)

that i understand.... but what im wonderin is.... be it the lift or other numbers in the specs.... at what lift do the cam numbers start to be considered big v.s. small... like the 2 cams i used as examples... they seem pretty similar.... (link) comp cams 08-430-8 280HR ( http://www.compcams.com/Cam_Specs/Ca...?csid=180&sb=2 ) comp cams 08-432-8 XR282HR ( http://www.compcams.com/Cam_Specs/Ca...?csid=189&sb=2 ) .... are the specs of these 2 cams gonna define the cams as big/small.... somewhere in the middle?

Stekman

Those 2 cams are not similar (in duration, sure, but in nature, different), one is a single pattern (same lobe profile on both intake and exhaust) the other is a dual pattern (different lobe profile). The cam itself is not big of small. If it's put in a stock head, it's big. If it were dropped in my SB2, it would be small. There is no big or small.

If you were picking between the 2, like I think you're looking at doing, go with the dual pattern grind.

weaz4200

iTrader: (2)

Those 2 cams are not similar (in duration, sure, but in nature, different), one is a single pattern (same lobe profile on both intake and exhaust) the other is a dual pattern (different lobe profile). single pattern n dual pattern...? elaborate please.. If you were picking between the 2, like I think you're looking at doing, go with the dual pattern grind. not thinking about those 2... just as reference.... u said u'd go with the dual pattern grind..... u see its answers like urs that i want to be able to understand..... like what is same/different lobe profile on intake and exhaust gonna mean.... and y u say the dual grind is better... u must have some info or knowledge that is causing u to make that choice.... n that is the knowledge that i want to gain.... so lets say roles were reversed.... n i was helping u.... id like to b able to say something like.... of those 2 cams... cam A will give u this end result (with a descrpition why) and cam B will give u this end result (with a descrpition why)..... n yeah i can see a slight difference in specs.... so a question that i could ask would b... how much of a difference will .005 make... like the 280HR (0.352) n the XR282HR (0.347) (Lobe Lift: Exhaust).... what do those numbers determine.... other than lobe lift on the exhaust.... what will that slight difference in numbers do performance wise? get what im sayin?

gregsz-28

iTrader: (1)

A dual pattern cam is good to use with stock heads because the exhaust side of a stock head usually won't flow as well as it should in relation to the intake side. A dual pattern cam is used to compensate for this, by being more aggressive on the exhaust side, with more duration and lift.
Aftermarket heads usually won't benefit from a dual pattern cam.

And if you want 500 hp, you'll probably want an aftermarket crank anyways, so you might as well get one to be used with a one-piece seal and just use a roller block.

weaz4200

iTrader: (2)

now thats what i call an answer... straight to the point and partly explains what i need to know.... thank you... so basically in a nutshell... dual cams are better suited for stock/ used heads because the exhaust sides of the heads are caked up with exhaust (carbon)... sound about right? n new heads will be better complimented by a single pattern....got it... that was what i was planning... considering the block i got has no crank.. n the 305 crank wouldn't work right? plus i need a 400 crank for a 383... i do know one thing... i want AFR heads... a question that i do have about heads is... (for reference... http://www.summitracing.com/parts/AFR-1040/ ) Intake Valve Diameter is 2.050 in. and Exhaust Valve Diameter is 1.600 in.... why cant they be the same size? do they even have heads with the same size? another question,,, does anyone know where i can find info about what heads would b good for a 383... i think a while back i was talkin with someone n they said anything over 200cc would b overkill (for 500 hp)... n they suggested something like the AFR 180cc.... so lets say i got these heads... http://www.summitracing.com/parts/AFR-0916/ ... they have a Maximum Valve Lift of 0.600 in... how close to that number do i want the specs for the cam to b? n if i for the sake of reference i go with the 280HR which has a valve lift of 0.525... is that good? do i want more lift (try to get as close to .600 as possible)/less lift?

gregsz-28

iTrader: (1)

Incorrect. It is simply because of poor design.
For example, stock 462 heads will flow 212 cfm @ .500" valve lift on intake, and 134 cfm on the exhaust side @ .500" lift, which is about 63% of what the intake side flows.
On the other hand, AFR 210's flow 271 cfm @ .500" valve lift on intake, and 198 cfm on the exhaust side @ .500" lift, which is 73% of what the intake side flows. Optimally, the exhaust side will flow about 75% of what the intake side will, which is why exhaust valves and ports are smaller.

[/quote] n new heads will be better complimented by a single pattern....got it... [/quote]

That assumtion will usually be correct.

[/quote]that was what i was planning... considering the block i got has no crank.. n the 305 crank wouldn't work right?[/quote]

Yes it would, it is the same as a 350 crank, a 305 only has smaller displacement than a 350 because of a smaller bore, but it won't give you a 383, you would end up with a 350.

[/quote]plus i need a 400 crank for a 383... i do know one thing... i want AFR heads... a question that i do have about heads is... (for reference... http://www.summitracing.com/parts/AFR-1040/ ) Intake Valve Diameter is 2.050 in. and Exhaust Valve Diameter is 1.600 in.... why cant they be the same size? do they even have heads with the same size? another[/quote]

No, there are not any SBC heads with valves the same size. That would be a terrible design. And besides, two 2.02" valves wouldn't even come close to fitting in a 4" cylinder bore, since the valves would hit the deck of the block.

[/quote]question,,, does anyone know where i can find info about what heads would b good for a 383... i think a while back i was talkin with someone n they said anything over 200cc would b overkill (for 500 hp)... n they suggested something like the AFR 180cc.... so lets say i got these heads... http://www.summitracing.com/parts/AFR-0916/ ... [/quote]

For 500 hp you could use stock heads, such as 462 heads or vortec heads, but that probably wouldn't be very street friendly. I'm sure there are lots of threads here on TGO about 383 builds, but nothing is easy to find with the search here on TGO.


[/quote]they have a Maximum Valve Lift of 0.600 in... how close to that number do i want the specs for the cam to b? n if i for the sake of reference i go with the 280HR which has a valve lift of 0.525... is that good? do i want more lift (try to get as close to .600 as possible)/less lift?[/quote]

You wouldn't need a cam with .600" lift to make 500 hp, at least not with any AFR heads. I don't think any of us know yet what you plan to do with the engine, and you'll also need to provide more info about what parts you already have, what you plan to get, etc, so if you want advice on components we'll need to know that stuff.

weaz4200

iTrader: (2)

just wanna start by sayin...gregsz-28... thanks for help.... i like the way you answer questions... very detailed... now... stock 462 heads... the obvious assumption..is stock.. but what is the 462 number... stamping? so most heads have an exhaust flow around 75% of the intake side? why usually? .... yeah.. didnt even think about that... .... what do u mean by not street friendly? (elaborate)... yeah..so is the internet... its like if u dont use exact/perfect phrases u cant find what u want(at least not quickly).... explain please... u see... thats the type of knowledge im trying to aquire... just from my question u have already devised that i dont need that big a cam... how? where can i learn and or get the info that u know.... like y dont i need a cam with .600" lift to get 500HP? or better yet.... how much HP can a cam with .600" lift achieve? as far as parts none yet.... trying to sell the parts i originally had on the car when i bought it about a year ago... ive been talking to guys in my other thread on suspension...tryin to see what to do there..... the only thing i know is this... want a 383 (others are probably buildin em as well... but i want my own twist on it... wanna do something that few are doin)... wanna use AFR heads... as far as engine thats all i know.... i got a slight idea of suspension/rear end... transmission (not yet)... it seems that an engine build is more technical than i had originally assumed....n gregsz-28... im trying to figure out what parts to get so as i could tell u more... hence the reason for this thread and all my questions... dont think i mentioned this before but this is my first build.... just tryin to soak up knowledge... so if ur down with helpin me out id very much appreciate it.... that way i could get a list of what ill need but ill also have an understanding of why the parts i inevitably end u with are what work well (or what different combos will give me)... this build is mostly street... and maybe further down the line it'll see some strip time... so my last question would b... as far as engine... where do i start(in what order do i choose parts)? got the 350 block...wanna make a 383 stroker... so i would start by looking at a rotating assembly?

gregsz-28

iTrader: (1)

Chevy heads are commonly referred to by the last three numbers in their casting number, for example 462 heads, 219 heads, 416 heads, 062 heads, 461...

"so most heads have an exhaust flow around 75% of the intake side?"

Not really. As far as I know there is no 'ideal' relation between intake and exhaust flow that will work well for every application.

".... what do u mean by not street friendly? (elaborate)... "

It would probably require a very aggressive cam, long duration, high overlap, (bad economy, poor bottom end power) cam lift is very limited on stock heads.


"explain please... u see... thats the type of knowledge im trying to aquire... just from my question u have already devised that i dont need that big a cam... how? where can i learn and or get the info that u know.... like y dont i need a cam with .600" lift to get 500HP? or better yet.... how much HP can a cam with .600" lift achieve?"

I'm sure without machining a pair of AFR 210's you could see 800 hp, so my point is that you don't need to try and get every last bit of power out of those heads by using a cam that aggressive. You could get 500 hp with a cam like this: http://www.compcams.com/Cam_Specs/Ca...?csid=151&sb=0 and any pair of AFR heads, and still have an engine that would be fine with mostly street use.

"got the 350 block...wanna make a 383 stroker... so i would start by looking at a rotating assembly?"

That would be a good place to start. Here are some good rotating assemblies: http://www.speedwaymotors.com/Premiu...mbly,3177.html

But you can't get those with a crank that uses a 1-piece seal, so to know if they will work with your block, we need to know more info about it. Did it originally use roller lifters or a 1-piece seal? Or, maybe you can look up the casting number to find this out if you don't already know.

weaz4200

iTrader: (2)

one site says 14093638 350 86-87 Truck One Piece rear main seal
another says 14093638 350 87 Camaro One Piece rear main seal

off the mortec site...says....
14093638...350...87-95...2 or 4...Roller or flat tappet cam, one-piece rear seal

here is link to pics of block (350) ( http://s281.photobucket.com/albums/k...ertweaz/block/ )... disregrad the parts... their from the 305.. so now what...its a 1 piece...

gregsz-28

iTrader: (1)

It looks like it is a roller cam block.
You would need a crank such as this: http://summitracing.com/parts/ESP-103523750/
, that uses a 1 piece rear main seal.
Any of these cranks, with that block, (assuming .030 overbore) will give you a 383: http://summitracing.com/search/Part-...n/?Ns=Rank|Asc

Quick reading material for you: https://www.thirdgen.org/forums/tech...-identify.html

weaz4200

iTrader: (2)

okay... so say i go with like a scat or eagle rotating assembly.... forged is better than cast right.... so whats the max HP a cast v.s. forged crank can handle? now when looking at rods... i or h beam...(elaborate).... also... which piston design is better flat\ dished\d-cup\dome? and whats better internally\externally balanced? so once i decide on a rotating assembly... what do i go with next?

Stekman

Yes forged is better than cast. I've run cast crankshafts on engines putting down 550ish crank HP/6000 RPM with no issues. It's not a maximum strength issue. It's a how much shock is getting placed on a crankshaft. A 600hp car with a cast crank could live fine on normal street use. It would get snapped like a twig on a drag motor where torsional loads are much higher.

I beam or H beam refers to what the rod looks like. The I beams cross-section looks like an I, whereas the H's is..well, an H. I am willing to put money on for whatever build you're intending, either rod design would work fine. H beams are generally rated stronger, as they have are generally stiffer. I do say generally, though. A rods overall strength is merely metallurgic properties and cross section. You can design an I beam and H beam with the same metal and to have the same cross section, thus having equal strengths. However, the H beam will be stiffer, due to the function of shape. Again, don't put too much effort into the H or I beam thought. Chances are if you find a pre-assembled rotating assembly kit, it would have either H or I, and those would be fine. A quality rod bolt takes precedence over rod design.

Reverse dome and small chamber heads are the best combination. Dome is the "worst" at least in terms of flame travel. Get the piston design with whatever -cc's yield the proper compression ratio. Smaller CC's will naturally be a flat top design with valve reliefs. Larger -cc's will automatically be reverse dome or complete dished. Find the correct cc's to match whatever heads you chose to yield the correct compression ratio. Take into account deck height and head gasket thickness.

Internally balanced is what most SBC's came as. 400's were externally balanced. I prefer internal on all my builds as the counterbalance for the rotating assembly is inside the crankcase, more along the center axis of crank rotation. External balance places the counterweights outside on the balancer and flexplate/flywheel, which, at high RPM's can stress the crank.

Heads are next.

gregsz-28

iTrader: (1)

Any of these kits will work, and since you'll probably end up with 64 cc heads, you won't want dome pistons, but not the +31 cc pistons either. You'll probably be choosing one of the kits with pistons between +5 cc and the +12 cc.
http://summitracing.com/search/Secti.../?Ns=Price|Asc

weaz4200

iTrader: (2)

so basically for 500+ like i want to achieve for the street u say its fine... every now n then if i decide to take it to the track it shouldnt be a problem? so I or H.. either works.. .... what kind of rod bolt... talkin bout brands?Reverse dome...dont think ive heard of those.. is that another name for one of the ones i mentioned? was thinkin "0" deck height and .040" gasket... sound good? Internally balanced... can they b internally balanced b fore i order them... or does the shop i get block work done at gonna do it? i kinda understand but not really... can u explain it a little more.? heads... i want AFR's... just not sure if i want the 180 cc's or the 195 cc's.... n after heads what typically comes next? if not dome then which design? actually got a few questions..... what about scat? whos better eagle or scat?.... how good are the pistons in these assemblies? i think a while back someone suggested i go with KB pistons... u guys know anything bout KB? n im curious if i called up summit or whoever i buy it from if they can interchange the pistons for different ones?

gregsz-28

iTrader: (1)

A cast crank should be fine.
For rod bolts, you can use ARP rod bolts, and just about any aftermarket rods will be good enough.
Reverse dome=dish
A rotating assembly can be balanced before you buy it, or any automotive machine shop can do it, which is what you'll need to have done if you buy rotating assembly components individually.

Quote:
I prefer internal on all my builds as the counterbalance for the rotating assembly is inside the crankcase, more along the center axis of crank rotation. External balance places the counterweights outside on the balancer and flexplate/flywheel, which, at high RPM's can stress the crank.
i kinda understand but not really... can u explain it a little more.?

I think he explained it very well. The added weight if an externally balanced engine is further away from the center of the crank, and weight has more effect the further it is from the center of rotation.

Eagle or Scat... one isn't necessarily better than the other, IIRC they get the castings for their cranks from the same source. In the engine I am currently building for my Camaro I used KB pistons, they seem to be very good quality, and I haven't ever heard anything bad about them.
I doubt that most retailers would be willing to interchange components in kits, but it can't hurt to ask. With most kits you aren't saving much money anyways, so you might as well just buy the components you want individually.
After you decide which heads you want to use, the next step is to chose the valvetrain and type of intake you need.

weaz4200

iTrader: (2)

so an internally balanced assembly has the crank drilled n weights put in... n externally is somehow balanced through the flexplate/ flywheel n balancer (meaning the harmonic balancer)? so if thats the case n its externally balanced... dont u need the flywheel/felxplate n balancer the company used to balance it? one question about buyin parts separately... lets say i was to buy all parts separately... if the crank was internally balanced wouldn't i need to take all the parts of the rotating assembly assuming i bought all eagle parts except for pistons (KB instead) n have it balanced again? hope u understand what im askin.... this might b easier to understand... do they balance the rotating assembly with all the parts in the kit or is a crank balanced by itself? n if so... would changing pistons cause a need to re-balance? so how do i go about doin that exactly...

weaz4200

iTrader: (2)

anyone know the answer to my previous post?

Atilla the Fun

what was the question? seriously, it does kind of get lost in there. I get the impression that Stekman has built about as many 383s as I have. Too many to count. Internally balanced kind of depends on what you're using. It's cheaper and easier with 6" rods than with 5.7" rods, and if you're using an '87-up block, then you'll still use a flywheel or flexplate that has the balance weight on it. Whoever does the balancing should not only already understand this, they should already own their own assortment of SBC flexplates. And it is okay if they balance it with a flexplate while you install it with a flywheel, if that be the case. When new cranks are finish machined, they're balanced to a common bobweight, say 1850 grams. But if your other parts only yeild a bobweight of 1750 grams, then the crank will need to have metal removed from the counterweights. If you order a kit that comes with crank, rods, pistons, pins, rings and bearings, and it comes balanced, then that means the crank gets re-balanced for those parts before UPS delivers it. And if you don't like the pistons in the kit, order the kit with other pistons, rather than paying for yet another set of pistons and a third balancing.

anesthes

iTrader: (12)

There is really two ways to do it. Either you build/buy a proven engine combo and have fun, or you keep trying different things until your happy.

I spend thousands of dollars every year trying things. I learn a little more every time, break a lot of things, and waste a ton of money. But what else do I have to spend my money on? (well, other than the two 4 hoofed primadonna's in the barn..

I haven't built a carbed motor since the late 90s, and you know. One day I woke up and said "man, I wanna build an older muscle type rig". I've got a 400 block at the machine shop right now, and I don't skimp on machine work. AFR 195 heads will go on it, a singleplane manifold with a 750 holley. A solid roller camshaft. Gonna be fun.


I think you should take a breath, and say "guys, I want a car that does this and a motor that does that, what should I do ?"


-- Joe

Atilla the Fun

I gotta agree with that. Only the engines I build are for others, so I'm not investing my own money, though I get to try every idea I've ever liked, and find out how well it works. Just tell us your goal and your budget, and we'll share our proven results. Pick one, copy it detail for detail, and enjoy.

weaz4200

iTrader: (2)

okay deep breath... let me try to break it down... from what i gather from you guys is that your tellin me to just say what i want and u tell me what to get.... then i get it... install it and im done.... does that sound about right? if thats the case then no.... i dont wanna do it that way.... im here talkin with you guys and askin questions so that once im done with this build....i understand more than just.... the part works because i was told so.... like the 2 of you guys said... and... .... with those 2 comments i can ask this question.... lets say i tell u... for example i want 500+ HP and i want it more for the street with the option that if i so choose i can take it to the track and change up parts easily because i chose quick interchangable ones... and i want the suspension to be slightly stiff but not so much that it feels like im drivin a tank... etc...etc... so basically.... i want 2 things to happen... the first is.... once im done i wanna have a finished product that is my own...not a copy of something already done....i know i will have similar components to others....but im not a copy cat... and the second is.... u ask what i want... i tell u... n u say what i should do.... but i wanna have the knowledge to be able to answer questions myself,like u guys wanna do for me.... if i say 500 HP n u say for example.... get these heads.... http://www.summitracing.com/parts/EDL-5089/ (just for reference)... well that doesnt help... because i have yet to understand how and why those specs suit me... i wanna know how to crunch the numbers... id like to understand why a 195cc head would be the ideal one to pick v.s. a 215cc head for the reason that 215 would be to much head for the engine i build, depending on what i build... and why a cam with lets say a duration of 224 would be better for whatever i build in the future instead of a cam with 244... hope u get what im sayin.... if i wanted a quick solve to my problem... id just buy a ready motor like this one... http://www.enginefactory.com/500hp.htm ...and be done.... i wanna know what u guys know so that i could as well one day teach someone how to build their own.... instead of just..buy this...itll work...

anesthes

iTrader: (12)

1) 500HP out of a 350 is tough, but not impossible. You will need high compression, and a big cam. The camshaft will lope and not provide much vacuum, which will effect the brakes.

2) You need heads that flow at lest 260cfm at max lift (intake), and 190cfm exhaust.

3) The quench will need to be within spec (.035-.045) so you can run the most timing and compression on pump gas without detonation.

4) Reverse dome pistons and small chamber heads have better flame travel and detonation resistance than dome pistons and large chamber heads.

5) You will probably want to shoot for around 10.5:1 compression ratio with the 3.75" stroke crank.

6) You need at minimum a nodular crank for an auto with a loose converter (3000 stall), or a forged crank for a manual.

7) Smaller runner heads tend to make more low end torque but sacrafice top end breathing. Larger runner heads are great on the top end but kill street cars when it comes to low rpm, especially a 35mph cruise. More displacement will change your operating range as well (lower it), so you want to be reasonable on the heads. A 195cc head is good compromise for a street motor. For a ultra high-winding (6800-7000rpm shift) I'd go with a 200+ cc head, but for a street car that will shift in the neighborhood of 6k (a 383 for example) a 195cc head is the best of both worlds. It will support the upper RPM, but also provide decent port velocity down low.

8) Back to the camshaft. You're going to need enough duration and lift to fill the cylinders. A 383 will take some of the kick out of a cam (2-4 degrees) over a 350, but to make 500+ horsepower you're going to still need something in the 230+ degree area at .050". You also need to make sure your lift is reasonable for the heads. (i.e, enough for flow but not exceeding spring capabilities).

Hydraulic cams for street cars are ideal due to less maintenance, however a hydraulic camshaft has a few drawbacks. 1) You loose some lift due to the nature of the hydraulic lifter, and in fact some lifters may be "pumped up" more than others which could make each value have slightly different lift specs at the valve, or cause valve float prematurely.

Solid cams are way more maintenance, but are more consistent and typically have more agressive ramps possible.

Roller cams have more aggressive ramps which mean lift comes in early on in the duration. A solid roller makes the most power, but again with maintenance issues and risks.


The camshaft needs to do a few things. it needs to operate the engine in the powerband desired, fill the cylinders, and bleed off excess pressures to avoid detonation (due to higher compression). So while a 224 degree camshaft will work wonders on a 10:1 motor making around 400hp, a 230+ degree camshaft will put a 10.5:1 motor into the high 400s, or 500+ horsepower without detonating. (assuming aluminum heads are used, etc).


You will also need a good exhaust. 1 3/4" primary headers, if possible length tuned to the operating range of the camshaft.

To simulate builds try using Comp Cams CAMQUEST6 software. It's free, and comes with flow files for most popular heads. (i.e, trickflow 23, and AFR 195). You can spend hours designing your combo to figure out the right head + cam combination to make the most power.

-- Joe

Stekman

Not to be an @$$, but have you tried searching? I could run a search right now on all the terms and suggestions that have been posted, and get at least a copious amount of information. This thread could go on for 4 years on the physics and theories of engine operation, and you'll still only be scratching the surface of engine dynamics. Spend a night searching every possible term you can imagine.

anesthes

iTrader: (12)

True. I think however, He's looking to simply know why he should select parts in category A rather than category B. More of a cliff notes version.

-- Joe

weaz4200

iTrader: (2)

anesthes... i have read through your post n i will get back to it i a bit... n tis true... it is kinda like cliff notes...but very detailed ones.... now as far as STEKMAN's reply( n i hope u read this).... u say that u dont wanna be an @$$... n i understand where your comin from(im not offended)... n i know that this could take a while.. but let me break it down for u.... and dont be offended by what im about to say.... ill start with this.... first off... im askin all these questions not just to get an answer to my specific build.. but for any newbie or person with the lack of knowledge that may be in my same position... its easy for someone that knows their S**T to sit here and complain about what it is that im askin.... but i was under the impression that TGO as well as a lot of forums be they about cars or computers or even sports...are here to help... but also bein like a community of close people (even possible friends) that can help out one another when in need... plus u also say look up terms... well its easy for someone that knows the correct terms as opposed to myself... who is just starting off... u think i wanna ask every stupid little question that someone of ur caliber might look at and say... thats easy... well for me its not easy.... and again.. not to be rude... but (not sayin ur like this) a lot of people that i speak with that post replies like urself make me feel like i shouldn't even bother comin here... like im beneath u or somethin... n i dont want that to be the case... but then on the other hand... there are guys like... 91_5.7_TPI....(look him up if u dont know who he is) who have helped me out with my FRONT SUSPENSION PACKAGE? thread.... n he could of said the same to me as far as... "u dont know jack... look it up"... but thanks to him... i have learned a lot of the terms u say i should look up... plus he is more than willin to spend the time to help out someone in need... so basically what im sayin is... y do u care if it takes a year or even 10 years.... and also... no one is forcing u to read these threads.... ur hear of your own free will.... so if u wanna help... ill be more than glad to listen... cause i basically take a lot of what u guys say as GOLDEN.... but if not then dont read it.... go help others that already know their S**T.... cause i personally am hear to speak with people like 91_5.7_TPI and Anesthes that have no problem explaining stuff be it a topic that can be explain in 1 sentence or 1000 sentences... catch my drift.... and im SORRY to all the MODERATORS or OTHERS that have to read this... i know that the forum is for 3rd gen stuff... but i had to get this off my chest...again... IM SORRY... now hopefully we can put this crap behind us and talk about what we should be talkin about in the first place...

weaz4200

iTrader: (2)

now anesthes.... my first basic question is.... how can i find all this info ur givin me... this is the type of info im lookin to learn and understand... any books an/or instructional dvd's u could recomend that get this in depth with the explanations.... now ill go thourgh your post in order and ask my questions... how can i find out based on engine size (LIKE 350 FOR EXAMPLE) what the max possible HP i could get out of it? and i still dont get this... what is considered a "BIG" cam...and why? and takin STEKMANS advice... i looked up LOPE... so the intake and exhaust valves stay open together longer...right? so why is that a problem? and effect brakes why??? Y? how do u calculate that? quench i now understand... due to what... because there is less space and its travels quicker? 5 this is yet another thing i wanna understand... what do u base that off of? what do u mean by loose converter? #7 on ur list.... where can i find that type of info? how do i know what cam will be enough to lift and fill cylinders? ....again how do u figure those specs? so then whats an ideal cam... a hydraulic roller?
again... how do i calculate this? y do u say than number? and if u guys arent aware already.. i have a lot of questions... n if you know of any thing i could look at or books or dvd's... let me know... anesthes... i wanna know all the stuff u just mentioned.... how would u suggest i go about learnin all this stuff? so i could anwswer any question that someone asks me just like u have done for me(which i appreciate)?

gregsz-28

iTrader: (1)

A cams duration is how long the valves stay open. Cams with less lobe seperation will make more power at higher RPMs, but will have poor idle and low RPM characteristics, such as making less vacuum, because of exhaust gasses being forced into the intake at the lower RPM.

It is important to choose a cam that will put the dynamic compression ratio in the correct range, between 8:1 and 9:1. A cam with less lobe separation and more duration, causing the intake to close further after BDC, will lower the dynamic compression ratio, by shortening the effective compression distance of the engines stroke.

Primary tube diameters need to be larger for larger engines, since they have more cylinder volume, so they need to be able to flow more. To help decide what cam to use, in relation to CR, you can use a dynamic compression ratio calculator, and see what cams will put your engines CR in the correct range.

By converter he means the torque converter. The stall speed is the RPM at which the rear wheels are forced to spin, overcoming the vehicles weight and brakes.

weaz4200

iTrader: (2)

just curious.. n e one willing to talk via IM? i think that would make stuff a lot easier... plus that way others cant complain... if not thats cool...

Stekman

I'm bored and can't sleep. This could be long...

There is no "max" hp out of a 350 block, aside from the actual physical strength of the block itself - 5-600hp is about when you start looking at aftermarket blocks. If the block were able to hold the power without splitting in half, I could build an 800hp 350 block.

Again, as I said before, "big" really isn't a good term for a camshaft, as it's all relative to the rest of the components used to build the engine. But for sake of explanation, "large" camshafts are generally ones that have high duration figures, close lobe seperation angles, and larger lift figures. But, again, I say that it's relative to the rest of the engine. For example, say on a bone stock engine (stock heads, stock compression, stock intake, etc), a cam with 220/230° duration @.050" and lift in the .500's would be considered "huge." However, if I were to take that and drop that into a race motor that has 13:1 compression, heads capable of flowing over 350 cfm and lift figures in the high 600's, that same cam would be considered small. Cam size needs to be matched to intake ports (velocity). More later.

You don't calculate cfm. It's cast into the cylinder heads. Larger cylinder head runner cc's generally flow more cfm than small cc's. So a 230cc intake port vs. a 170cc intake port, the 230 will have higher CFM rating. Great for high RPM engines, where most of the life is spent above 3-4000 RPM and the valves are flying open and closed. Then the high CFM is needed to cram as much air into the cylinder as possible, since the valves are opening and closing at an ungodly fast rate. Take the same large cc runners and put them at idle to low RPM (think daily driving), and the valves are now opening and closing at a much slower rate, meaning that per unit time, the valve is off the seat longer. This results in a loss of port velocity - the air charge moving through the intake, into the cylinders, just doesn't move that fast. Think of it like 2 rivers, flowing the same volume of water. One through a narrow channel, the other through a very wide channel. The narrow channel (small cc intake runners), moves the water faster than the wide channel (large CC runners). Same situation with lower RPM function. Under the high RPM operation, as I said above, the valves are now opening and closing in much more rapid succession, so you need the larger cc's to move more volume of air per shorter unit time. This is why a large CID motor, like a 383 or 400 will get choked out by stock heads by 5000 RPM. Anything above that, and the heads are not capable of flowing enough air to feed the engine. The intake/exhaust cfm is a simple matter of air in, needs a way to get out. The engine is basically an air pump. If you have massive amounts of air in, you need similar on the exhaust. Most aftermarket castings are good about maintaining a decent I/E ratio. This is why dual pattern grinds were created. Stock heads are "alright" on the intake side, but terrible on the exhaust side. So the dual pattern grind keeps the exhaust valve open longer, and usually, to a higher peak lift. All in effort to move the inert gas out of the chamber.

Combustion chamber shape and piston shape, sure, in a nutshell it's sort of faster flame travel (faster burn rate), could also be argued that a higher percentage of the combustion pressure is placed over the center of the piston (more force in a downward direction rather than outwards). But this is not to say that flat top doesn't have it's advantages, either.

For compression, run a search on detonation. Anything above the numbers that have been listed, on pump gas, run into detonation problems. I run about 13.5:1 compression on my SB2. I'm also forced to use race gas.

Any cam will "fill the cylinders." It just depends at what RPM you want to achieve this. See my explanation above. But to expand on the above, the cam can also have the same effect as too large or too small of intake runner cc's. Keep the valve open too long in relation to degrees of crank rotation (this is the duration figure of a camshaft), and at low RPM's, when it takes a longer amount of time for the crank to rotate x degrees, then you are going to have a lower velocity with the larger cams. Smaller cams have better low end velocity, great for torque applications such as 4x4. Larger cams have zero low RPM velocity, obviously doing the opposite - kills low end torque, but the massive amounts of duration keep the valve open longer, which feeds allows the engine to breathe at high RPM's. This, in correct combination with the proper cylinder heads is what determines an engines overall RPM range. Large CID with small intake CC's and a fairly small cam will make great low end torque, but won't rev past 4.5-5000 RPM. On the flip side, same CID with massive intake runners and a huge cam, say above 250° duration, will be an absolute dog on the street, no low end torque, but will be able to rev rather high - 6-7k RPM. Most applications that see street/strip, are best served in the 2-6k RPM range. Which, for 99.9% of the cams, will end up having about 220/230° duration. This is why we all say look for 230° duration. It's what works.

Generally, when you look at aftermarket heads, they show a flow chart. How much CFM the ports flow at given lifts. .200, .300, .400" etc. Looking at one of these you will notice that towards the top half, say the .500" and .550" lifts, the difference between CFM may only be 4 or 5. It's at this point where cam lift beyond these figures is pretty much pointless as there's no added airflow above said lift figures. So while you could put a cam that has .600" lift, the heads are incapable of actually flowing more and more and more air from maybe .500" through .600". That being the case, for that particular instance a cam with a lift of just over .500" would actually be more beneficial to the motor than going to the absolute lift figures supported by the physical clearances of the heads.

Anything under 7k RPM and street duty I always suggest hydraulic cams, unless it's a race car. In which case, then you can look at solid tappets. So yes, keep to the hydraulic roller variety and you;ll be fine. The way companies grind ramp rates (the rate at which the cam lobe opens the valve), the difference between a hydraulic roller and a solid roller (again, street duty application), won't be noticeable. It's once you get to the serious race engines that scream at upper RPM's all day long that the lighter weight valve train components and extremely aggressive ramp rates of solid roller becomes advantageous. For street use, though, those aggressive race-spec solid rollers are extremely harsh at low RPM's. Solid rollers need oil pressure. Lots of it. And that's at high rpm's.

I have no clue as to what I actually answered. I just kind of rambled. I'm going to sleep now.

Atilla the Fun

"once im done i wanna have a finished product that is my own...not a copy of something already done....i know i will have similar components to others....but im not a copy cat... " If you don't have your own engine dyno, then you can't hope to do better than to copy a proven combo. " but i wanna have the knowledge to be able to answer questions myself,like u guys wanna do for me" You seem to want in 5 minutes and one long thread what took each of us many years and many thousands of dollars and many busted knuckles to acquire. One of the best ways to learn is to try other guys' proven combos. " i wanna know what u guys know so that i could as well one day teach someone how to build their own.... instead of just..buy this...itll work.." that's fine, and I think it's a good thing, but it frustrates me that you seem to think you can get that from one long thread. And besides, whoever replaces Obama will be just as bad for our hobby, in 20 years, our hobby will be dead, no point in teaching. The things to learn are the things that'll make us enough $$$ to let us keep our cars, and enjoy them, long after it's illegal or impossible to drive them every day on pump gas. Our knowledge can no longer be profitable. Guys like Stekman and I really SHOULD be getting paid for telling what we know, just like guys like Ken Duttweiler. But unlike Ken, we enjoy helping fellow enthusiasts.

weaz4200

iTrader: (2)

like i mentioned before... plain and simple... if you dont like the threads then dont read them...im not here to talk to downers... if u dont like givin your knowledge for free...then be my guest and go charge people for it....i on the other hand am not selfish with my knowledge... im tryin to learn outside of the forum...thats why i started school this summer...to learn all or most of the stuff i learn here... again.. if your not here to help then dont waste ur time nor mine.... stuff you've said and what im typing right now have no reason to be posted in the forum... this is not a B***H and moan forum.. but rather a forum to learn info... so if n e one has anything else to B***H about... just keep it to yourself... and stop postin your complaints in my thread...