Casey_Butt

I'm thinking about building a 334 stroker. It'll have Trick Flow 23 aluminum heads with 56cc combustion chambers. My cam is a comp cams xr258hr - advertised duration 258/264, (206/212 @ 0.05") Lift .480/.488. The compression ratio will be in the 10.3:1 to 11:1 compression range.

Is 11:1 CR with this cam and heads too high for pump gas? How about 10.3:1?

Can anyone help me out?

84z28350

It depends on your dynamic CR.

My new iron head motor has 10.8:1 static comp but only a 8.7:1 dynamic CR and is has no problem running 91 with gobs of timing.

Casey_Butt

Dynamic Compression Ratio will be 9.67:1 with 10.3:1 static CR,

and Dynamic Compression Ratio will be 10.36:1 with 11:1 static CR.

What do you think?

sofakingdom

iTrader: (1)

I think you're spending too much money, and getting too little out of it.

Instead of getting your 305 a "stroker kit" (3.75" crank etc.), get it a "borer kit" (4" block).

More bang, less bucks.

Of course, we're all too stupid here (speaking strictly for myself of course) to see the benefit of spending more and getting less; so if anybody smarter than me tells you the same thing I just told you, you'll just have to excuse them. I guess they don't "get" the importance of spending more to get less.

Yes that's too much CR for that cam; or, too little cam for that much CR. It will be detonation city.

Sonix

iTrader: (1)

that's a very tame cam. Even with AL heads, that's too high of a dynamic ratio for me to be comfortable.


And a 335 stroker 305 is a bad idea. Go 350.

Casey_Butt

I don't want a 350 ...therefore, a 334 is a very good idea, I'll have to get the CR down though. Thanks.

Sonix

iTrader: (1)

hmm, not terribly logical. But if you're dead set on it, then that's what you're going to do.

However I would recommend you talk to people who've been there done that, and see if they recommend it. Tunedport335, and anyone else with a stroker 305. There's plenty of other methods of doing something different, without doing something bad-different. Heck, you could destroke it!

larger cam is a good idea for starters.
get your quench distance right

then either;
hog out the chambers in those heads, or use different heads.
pick different pistons, with more dish

Casey_Butt

Well, it's going to be a street-only hydraulic-roller motor, so I don't want power above 5500 rpm or so (thus the short-ish duration cam) ...and the longer stroke 334 can have just as much torque and power as a 350 in that range, so I don't think I'd get any extra performance benefits from the 350 for my particular application. And I don't want to change the original block that came in the car ...it's a nostalga thing.

So, it's a get-what-I-can from a 305 hr block mission.

But I screwed up the dynamic compression ratio calculations: with 10.3:1 static CR, the dynamic CR will be 8.73:1. How's this on pump gas?

Apeiron

Not really. Build the two equally and the 350 will always make more power.

Sonix

iTrader: (1)

ok, that sounds more right. 8.5 is usually the max on iron heads and pump gas, so I think you'll be ok with AL heads.

but yea, more $ for the 305 stroker, and i'm not really sure it'd keep up with the same 350....

five7kid

iTrader: (14)

...and torque. . .

84z28350

your definately fine with that.

Same DCR as me and im fine on 91 with iron heads, i cant remember but you guys (assuming your from USA) have 92 or 93oct at the pump dont you?

With the aluminum heads you might even be able to run lower octane...

mw66nova

iTrader: (13)

your cam is WAY too small. you need something in the 235*/245* @ .050 range to benefit from all that your putting together. but to get that much duration without going too high on the lift, i'd think that a solid flat tappet cam is in order here.

Sonix

iTrader: (1)

nova, I think the two of you are on totally different pages.

plus a solid roller would make more sense in his roller block.

mw66nova

iTrader: (13)

what? i still daily drive mine, lol!

do they make solid rollers that fit into the stock hyd. roller keepers? that'd be cool!!!!! cause my next motor is based on a roller block and a solid roller would be way neat.

Sonix

iTrader: (1)

I thought a solid roller would fit there.... :shrug:


I think he's going more for economy, low end torque. Nova, what RPM does your 305 come online? do you have to rev it to 2500 to get out of parking stalls? I think your definition of "daily driveable" is different then the rest.... and, your concept of a fast 305 is also different

five7kid

iTrader: (14)

Crane 10510.

Summit p/n CRN-10510-16

Casey_Butt

Well, I'm looking for as much torque (and therefore horsepower) as possible from 2000 to 5500 rpm. In that range the 334 and 350 would be almost identical mod-for-mod because of the 334's longer stroke. Of course, above 5500 rpm and the 350 will start to show it's advantage more ...but this is a street machine that isn't aimed at high rpm use like that.

That's also why the cam has a duration of only 206 @ 0.05". With the Trick Flow heads that's plenty of cam until about 5500 rpm and should make gobs of torque up until that point.

So, the whole goal is torque and hp in the 2000 to 5500 rpm range (my stall is around 2000 rpm), and to keep the original block.

If I use a 0.051" head gasket I'll get the DCR down to 8.5:1. No problems. The 334 should get me around 350+ hp @ 5500 rpm and 400 ft.lbs @ 3500 rpm. That's a nice street-mannered car that should run into the 12s if need be ...and not be ridiculous on gas.

Sonix

iTrader: (1)

don't use a thick head gasket to lower your CR. You'll be tossing quench out the window.

the 8.5 DCR is ideal *for iron heads*, usually AL heads can take an extra point on the static, and i'm gonna guess on the DCR as well. 9.0->9.3DCR is not outlandish on AL heads, with good quench.

based on your post, it sounds like you're using Desktop dyno or something? I wouldn't trust it that far. There are some members here that will disagree with some of what you've said, as far as real world experience goes.

I'm on the opposite side of the arguement to you, i'd rather do the 350, however, you can do whatever you like with your car. Best of luck, and do post how well it runs when you're done

Apeiron

No it won't, because the 334's longer stroke is more than offset by its smaller bore.

Casey_Butt

The 334 has a longer moment arm than the 350, which is why it's torque would be comparable in the low- and mid-rpm range. Of course, it's 16 'cubes smaller so it'll give up that, but the difference wouldn't be that noticeable until the rpms build ...which is not that applicable to a street motor operating in the low and mid-ranges.

I don't have the DynoSim stuff yet. Coincidentally, it's in the mail though ...it'll be interesting to see how it matches up.

Apeiron

It has a longer moment arm, which would mean slightly more torque given the same downward force on the piston. That downward force comes from the cylinder pressures acting on the face of the pistom though. The 335's smaller bore means it has a smaller piston face, and so therefore has less downward force which cancels out the benefit of the longer moment arm.

This is to say nothing of the valve shrouding issues which already hurt the 335 to begin with.

mw66nova

iTrader: (13)

FRICKIN AWESOME!!!! thanks five7kid!

sofakingdom

iTrader: (1)

More money, less results.

Or:

Less money, more results.

Hmmmmmmm...... tough call.......

There's still too much CR, too much head, and/or too little cam, in your combo. Along with too few CID, too long stroke, and too small bore. Great recipe for wasting money while getting spanked, all the way around.

We appreciate your enthusiasm and desire to explore unusual territory and all that. However, there's a good reason that that's "unusual territory": it's because everybody that's done it, hasn't gotten any results out of it. And the people who do the "usual" thing, will kick its butt into the sewer. Basically if you spend the other $50 or $100 on your $3000 project to get a better block core with the larger bore, you get about 60 more HP and 70 more ft-lbs. Cheapest power money can buy. We all say that about $10/HP is the economic dividing line between a good value and a waste of money. So, how about $1.20/HP? Is that a good deal? ya think?

Or:

Spend more, get less.

Your call.

mw66nova

iTrader: (13)

sorry, i missed this post.

my cam makes power from 3000-6500rpm, though i only spin it to 6k right now. i don't have to reve it to 2500rpms to get out of a parking stall, it's just like anything else. the converter that ATI built is a monster, but only drives slightly differently than my buddies lt1 cammed stock stalled 305. it is a bit of a dog if i want to just lean into it to go around someone with the converter locked on the highway (say around 2000rpm) but if i jump on it, it screams.

my definition of a "daily driveable" car is something that can go anywhere without overheating and be able to be fired up on a regular basis with no issues. i don't have to even touch the gas pedal when i get in the car. one crank and it's wiggitty wiggitty ROOOAAARRR!!! and something that's not horrible on fuel. i average about 16mpg mixed highway/town. if i'm up on the highway with no intown stuff (like a road trip, which i wouldn' hesitate to do in my car ) it'll get 22+mpg.

what exactly do you mean by my definition of a fast 305 is different than others? i feel like everyone out there with a 305 should be able to run high 13's with no problem, but after hanging out with the stock/super stock croud for a little while, high 13's just ain't enough! i spent the money on the things that count to make these things scream: converter/gearing and valvetrain. and if you were going to really build a fast car with a larger motor, you'd be spending the money on the exact same stuff, so it's not like i spent money on things i shouldn't have. roller rockers, converter, gearing, cylinder heads, cams, all that stuff will go into the bigger motor if i wanted it too(heck, that's were it all started out at, lol!) though the next motor is going to be one bad mama jama with 10.5:1+ and some AFR 210's on a 383 ci sbc.

mw66nova

iTrader: (13)

here is my view on this whole thing. (coming from a guy with a decently fast 305) if you have the parts already, build the motor. shoot, the cylinder heads your looking at are good for even a mildly built 350+ motor down the road if you wanted to build something faster later. however, spending money on a combo like this is ludicris. my 305 defines budget. i bought all of the top end to top off a 10.2:1 360ci sbc. i drove it for 3500 miles and the block cracked (freak deal being that it had 3 sleeves in it and it just finally gave). i had a 305 block that only needed a hone with 7 good pistons. i bought a new piston, and a set of rings and had the block honed, that's IT! i've got $180 out of pocket to go from FAST broke350 to slightly less fast not broke 305. and it gets me around and has impressed the crap outta some people. this engine's soul purpose now is to help provide a decent enough power to get the car setup for handling more power. learning how to tune the chassis and whatnot. trust me, if you ever build your own motor, you will end up with the power bug...and you will only want more and you will never be satisfied.

Casey_Butt

"The 335's smaller bore means it has a smaller piston face, and so therefore has less downward force which cancels out the benefit of the longer moment arm."

The size of the piston face remains essentially unchanged (is increased by 0.03"), therefore any increase in moment arm length is accompanied by a linearly proportional increase in torque. This is why the 0.27" increase in stroke length that the 334 has over the 350 results in the 334 producing similar torque numbers at lower rpms (before piston speed and geometry become limiting factors).

sofakingdom

iTrader: (1)

OK, enough fantasy land about this "more torque" crap. That spank-of comes up every time somebody that's never built a motor, posts about doing this.

Torque = cyl pressure in psi, times piston area, times stroke. That's all there is to it. Pure numbers.

Now: assume equal cyl pressure (which it won't be, the 350 will actually have more, but let's be charitable to the charity case 334). Just pick any arbitrary cyl pressure #, say 1000 psi or something; plug the same number into both a 334 and a 350; and tell me how this mythical 334 is going to EVER get AS MUCH torque as a 350 at ANY RPM, let alone MORE.

More money, less results. Your call. Which, it's your money, and your car, of course; you can do whatever you want, and that's OK, we won't stop you. We'll even help you, because that way, we'll know for sure that with that combo you'll lose the race every time guaranteed. Nobody is making you listen to us or anything, much less do what we say. It's a free country and all that.

We'll just stand around and laugh.

{edit}: Oh, and if you DO go with the stroker kit, and put it in a 4" block instead of a 3.736" one, do the torque number on that one too. Makes the 334 look even dumber.

Casey_Butt

A 350 would develop 6.47% more torque than a 334.

I find it equally funny, when a person asks one question, but gets answers to another question which was never asked and is met with hostility from people who have no vested interest in, and an incomplete comprehension, of the topic.

Apeiron

Better check your math. A 350 has a 12.566 sq.in. piston face. A 335 has a 11.163 sq.in. face. That's a little more than 0.03" difference.

But if stroke is that important to you, stroke the 350 out and make a 383 to compare to your 335.

Casey_Butt

"Better check your math. A 350 has a 12.566 sq.in. piston face. A 335 has a 11.163 sq.in. face. That's a little more than 0.03" difference."

I was referring to the increase in bore. I thought you would figure that out yourself.

Apeiron

I'm sorry your incomplete comprehension makes you hostile.

Remember, free advice is worth every penny. Make sure you're getting your money's worth from it.
----------
I thought you were. A 350 has a 4" bore, a 335 has a 3.77" bore. That's about 0.23" difference.

Casey_Butt

I think I, in fact, have gotten exactly my money's worth from this.

When I asked the original question I expected the typical "you should get a 350" spiel. I never asked for that, and I never asked to be notified that I would be laughed at for asking a question about something other than the "holy" 350.

I, in fact, have a 350, which is being built in my garage right now. It has no bearing on the compression ratio in my future 334.

Apeiron, I'm sorry. I should have been clearer ...A 334 has a 3.766" bore. This is a 0.03" increase over a stock 305 3.736" bore.

Apeiron

Well if you got the impression that you're being told to build a 350, then I'm sorry.

You made some statements that made a few people afraid that your decision to build a 335 was based on some common misconceptions, and that maybe you'd be unhappy with the results.

In the end though, you can and should build whatever you want.

mw66nova

iTrader: (13)

you CAN get away with the c/r you have, but you NEED MORE DURATION!!!!!!

there i answered your question. if you don't like the answer, reconfigure your combination to have right at 10:1 static compression, otherwise, you need the added duration to help bleed some of the cylinder pressure off. i have a 10.4:1 aluminum headed 305 in my car RIGHT NOW that runs 12.5's with very little tuning. not only that but it runs off of 93 octane and i drive it everday to work and back (about a 50 mile round trip)

Sonix

iTrader: (1)

ah, ok. I don't have any experience with a large cammed motor, and I also have no experience with larger convertors. I wasn't sure if that meant it's like the clutch is out until 4000RPM on a 4000RPM stall speed torque convertor... (but hey, that's for another thread...)


What I meant, is that *most* members on this thread that still have 305's, brag about their stellar mid 14 second timeslip. They give high 5's when they hit low 14's. That's pretty normal *I* think. Then you have a budget 305 that runs mid 12's, so that's why I think your definition of a fast 305 is a little more.... well, you have higher expectations eh?



anywho, casey, a 335 is just like other motors as to it's compression ratio requirements, so try a search on that. Also, if you're still in the planning stage, i'd highly recommend you talk to others with 335 type motors, and ask their thoughts before you go for it. Otherwise i'd say stick with a 305, and beef that up with parts you can later transfer to a 350, should you have that rare desire

oh yea, and more cam! A larger motor, (probably espescially a larger motor due to larger stroke), will eat up the excess duration and not bat an eye. So that cam will feel like a stock cam, which won't really be worth your $$ to buy the cam right? I'd guess for another 8-10* duration on intake and exhaust on the cam, and that'd be about right for what you want.

sofakingdom

iTrader: (1)

With any size motor, you have to build it to attain optimum efficiency in the RPM range you want it to run at.

If you're building a motor that will turn 5000 RPM max, then you don't need, or even want, heads with big intake ports and high flow. Think of filling your cylinders with air/fuel as being like filling a series of buckets. If you have a whole string of buckets and you need to fill them at a rate of one per second, you need a fire hose. If you want to fill them at one per minute, you want a garden hose. If you want to fill them at one per day, you need aquarium tubing. If you have the 3rd situation and you use a fire hose, then you've wasted a whole lot of resources in setting up a fire hose you aren't really using to its capacity.

With heads it's even worse; too big of an intake port means too low of velocity in the port, which in turn means that the air/fuel just kind of drifts lazily along on its way to the cyl. The fuel droplets will settle out of suspension just like silt settling out of slow-moving water. The ideal intake port size is determined by CID, RPM range, and cam properties. For a 350, 190-200 cc intake runners are already too big for optimum street use; they don't deliver an advantage until near 6000 RPM. With even less inches, the problem of such a mismatch gets even worse. With that stupid bore/stroke combo and the RPM range you're talking about, stockish runners of 160 cc are already plenty big enough. Anything bigger is a waste at best, and probably worse, from the other bad effects of low port velocity.

There are a number of "dynamic compression ratio" calculators available all over the Internet. I suggest you download the one by Pat Kelley, it's real easy to use and understand, as such things go. Basically, their idea is, the peak cylinder pressure ("effective" compression under actual running conditions, as opposed to "static" compression) is determined by the intake valve's closing point in degrees, as well as by the static compression. Since the intake valve closes sometime well after the piston has started travelling upwards, thereby allowing some of the cylinder charge to "leak" back out, the "dynamic" compression is always lower than static. For any given grade of fuel, there's a range of "dynamic" compression within which the engine will operate properly. For pump gas, that range is in the low 8s; probably 8.2 - 8.5, for aluminum heads. Any lower, the motor will have poor low RPM torque; any higher, it will ping and detonate. It's not an exact science, of course, more of an educated guess. But I believe with the cam you picked, and a static compression of 11:1, your "dynamic" compression will turn out to be well above 9; which means, RACE GAS ONLY. In other words, not "streetable", even by the widest possible definition. If you can't buy fuel to drive it on the street, then it's not "streetable".

Just because your engine's internal dimensions are less common for this model of engine than some other combinations of dimensions, doesn't rewrite the laws of physics. All of the concerns above will apply.

The intake ports in the heads you have picked are TOO BIG for the small engine size you are talking about putting them on; especially for deliberately setting it up for low RPM use. The cam is a good choice for low RPM use; however, it's too small for the heads: you've got this GIANT port, and the valve at the end is just kind of barely cracked open, so what's the point of the HUGE port anyway? It's also too small for the compression, because the peak cyl pressure will be totally outside of the range that pump gas can work in. On the other hand, if you put a big enough cam in it to take advantage of the head flow and to work with the compression, it'll be a low RPM pig anyway.

All the way around, it's a mismatched combo. It's economically inefficient (i.e. you can get ALOT more results for ALOT less money by doing it some other way), and it won't run like you think you want it to. The parts won't work together. They'll fight each other, and you'll end up getting all the disadvantages of each, and none of the benefits of any. In other words, even MORE money down the drain.

mw66nova

iTrader: (13)

well, i agree with everything you've said, the trickflow heads he's referring to only have a 170 or 175 cc intake runner. with more cam, this motor has potential to make some decent power. WITH MORE CAM, lol!!! but if he's set on using the cam he's got, a set of untouched 113 heads would work just as well, if not better. or, a set of slightly worked over 416's.

five7kid

iTrader: (14)

I'm still trying to figure out what "I don't want to change the original block that came in the car ...it's a nostalga thing", Trickflow heads, and street-only have to do with each other.

As for just answering your question, as should be obvious, the question asked isn't always the right one. One of the great things about this Board is that people pick up on that. The more observations offered, the more we found out about your objectives and how your approach was actually leading you away from accomplishing them.

As for 350 vs. 334, let me suggest this: Every objective you have stated could easily be accomplished with a worked-over 305, including 305 heads. Since "nostalgia" is in your equation, doesn't it make a lot of sense to get to your goals using all externally-original parts? The stroker would add some bling, but very little in the practical realm.

mw66nova

iTrader: (13)

i could see a numbers matching b4c being cool, or a numbers matching 1le. but a numbers matching 305 car is kinda silly.

robertfrank

iTrader: (27)

would a ZZ4 cam be enough for him? I have been considering getting the trickflow heads my self.I figure if it's not that cam combined with 1.6 roller rockers would do the trick.

mw66nova

iTrader: (13)

no, if he wants to keep the current combo, he's gonna need something like what i'm running: 238*/248* @ .050 .480"/.500" 114lsa

ttypecamaro

iTrader: (2)

while i agree with getting a cam with longer duration for max potential and streetability, I just want to bring up tuning. the further from stock... the harder to tune.

also think of future goals. like, WHEN you get bored of the motor and you just need more power... you don't want to tear down and redo your pride and joy motor... so you start thinking about a paxton or a turbo or nitrous... then you start kicking yourself for putting high compression pistons in it! go 9.0-9.5 compression ratio. high compression is not recommended for low powerbands anyway, plus your looking at like a 3% loss of power due to low compression to enable a 75% gain with a supercharger or nitrous down the road.

88TPI406GTA

OK...how about this? Stop pissing away all this time on a 305-based block or a 350 and get a 400...I have never considered a 350 as "holy" being that it is the most manufactured engine of all time. Now a 400, 406, 415, 427, 434, etc...those are treading on "holy" status if you own a stock 305

As to the original question...I personally wouldn't go more than 10.25 to 1 compression with aluminum heads on 92 octane. The problem with this whole debate is that people who assume that 10.75 or 11 to 1 can be used, make many assumptions, including: that tuning is professionally done with a dyno and in a static environment where detonation or bad gas or 100 degree weather or any other issues cannot possibly rear their ugly heads. Be realistic.

Also, this one engine/car is not going to embody all of the your goals of power, original engine, daily driver, nostalgia, etc. with the way you are going. More cubic inches always means that you can build a milder engine and still be happy with the power...

Good luck.