TraviZ

iTrader: (2)

With the engine build in my signature, The only thing left to have this engine assembled is the cylinder heads, which I am about to purchase used or new, either way I am getting the new afr eliminators. I just wanted a final opinion from other people if I should go 195 over the 210's. I know with the 210's I loose bottom end but with my 3000 stall, it shouldnt be a problem. I just want lots of power.

grumpyvette

since your building A SUPERCHARGED 383 combo theres vertually NO down side and a NOTICABLE advantage to the larger cross section of the larger 210cc ports, youll tend to have lower BOOST readings but HIGHER volumetric efficiency and better power. BOOST is mostly a measure of resistance to flow, higher flow drops the restriction and helps fill cylinders making more power.

If you go with the 195cc versions Id bet YOULL regret not getting the larger port heads after awhile

TraviZ

iTrader: (2)

Yes I definitely thought about that, Just glad to hear I havn't overlooked anything. and of coarse with less restriction meaning less boost on the gauge, just means I can run a even smaller pulley

customblackbird

iTrader: (15)

get the 210cc heads.... u will prob make more power and still be ok for future upgrades. idk if your 42# injectors are gona be enought tho... im not totally sure of the power ur putting down... but i would guess 500 on the motor and 150 with the 13psi supercharger i would put u at 600-650 at the motor at least... are 42# good for that? ive been pricing rotating assemblies as well.... where did u get a 383 forged kit with 8.4 comp!!!!! i would love that! how much? and from where ?

im building almost the same thing all i need is a rotating assembly
383 9.0:1 comp (around)
HSR ported
30lb SVO injectors
58mm TB
patriot 195cc aluminum heads ported flow 260cfm at .5 lift 270cfm at .6
comp cams XFI280 230/236 .567/.571 lift 113 lobe
custom prom
LT headers and true duals with xpipe in my sig

im hoping for close to 500 crank hp but im keeping the comp ratio low bc im def gona flow boost at it down the road, prob like 10lbs procharger or something. and i'll have to upgrade my injectors as well. i only went with the 195cc heads bc i got them for 860$ shipped to my door and they flow really good for there size/and will keep me in my RPM range of my combo.

Sonix

iTrader: (1)

I hate to disagree (maybe I just like playing devils advocate..)

Look closely at the flow differences between the two heads. IIRC I looked at that before and noticed a very TINY difference in flow, with a fairly large difference in runner size (with the AFR heads).

You're using a centrifugal blower right? So the blower won't be adding any low end torque until it gets spooled up, also 8.4:1 CR won't add any low end, and neither will the big cam - or oversized port heads. I realize you've got the big stall and whatnot - but just make sure you're gaining flow by going to bigger heads, otherwise forget it.

grumpyvette

http://www.rbracing-rsr.com/runnertorquecalc.html


here’s a chart FROM THE BOOK,HOW TO BUILD BIG-INCH CHEVY SMALL BLOCKS with some common cross sectional port sizes
(measured at the smallest part of the ports)
...........................sq inches........port cc
edelbrock performer rpm ....1.43.............170
vortec......................1.66.............170
tfs195......................1.93.............195
afr 180.....................1.93.............180
afr 195.....................1.98.............195
afr 210.....................2.05.............210
dart pro 200................2.06.............200
dart pro 215................2.14.............215
brodix track 1 .............2.30.............221
dart pro 1 230..............2.40.............230
edelbrock 23 high port .....2.53.............238
edelbrock 18 deg............2.71.............266
tfs 18 deg..................2.80.............250

Potential HP based on Airflow (Hot Rod, Jun '99, p74):
Airflow at 28" of water x 0.257 x number of cylinders = potential HP
or required airflow based on HP:
HP / 0.257 / cylinders = required airflow


theres only about a 3% increase in CROSS SECTIONAL AREA between the two differant heads , even without a supercharger its not a huge change in low rpm tq or responsiveness,in fact its generally almost not noticable as its about a 200 rpm shift in the tq curve,and a supercharger easily more than compensates, infact its easily able to increase the volume significantly even at low rpms

then keep in mind that normal ports flow under negative pressure while a supercharger produces at least minimal possitive flow at low rpms

Sonix

iTrader: (1)

OK, so Traviz, do you have a flow chart for both heads?

Guest

I dont know of a single person that went with the 210's that has complained. Flow numbers arent everything.

Sonix

iTrader: (1)

What's the other differences? I assumed they'd have the same chamber design (swirl), deck thickness, etc etc? I thought the only difference between them would be port size, and port flow.

I *thought* the 195s had a smaller *more efficient* port design. I'm not trying to kid myself here, I know the larger ports will make more peak power, but if the difference in volume is larger than the difference in flow, then you're losing efficiency. And if you lose more low end HP then you gain in top end HP, then the area under the curve is smaller and you end up going slower. This is only a useful comparision if the HP lost is *above* the torque converter stall speed, etc etc.

Still, i'd like to see the flow numbers for both. IIRC there was only a 1-3 CFM difference in the .300-.600" lift range, or thereabouts. 260 vs 262cfm or something?
.75% difference in flow, 7.5% difference in volume would be a net loss to me. Those numbers are off the top of my head, so you can't take that to the bank - but that's just what i'm trying to get across.

What variables am I missing here guys?

grumpyvette

what your MISSING is those flow charts, the manufacturer posts, that you see are taken at a 28" of steady vacume , once you pressurize the port even slightly, and realize its a pulsed flow as the valve opens and closes between 7-55 times a second, the ball game changes significantly in favor of the slightly larger port
those posted flow charts are not really useful when your pushing airflow vs sucking air flow thru the ports, past the valves.
Ive only built a few supercharged engines for guys, but,
trust me on this, the larger ports have more addvantages than dis-addvantages, and the flow dynamics change radically when your forcing airflow thru a port at greater atmospheric pressure than standard vs sucking it in past the valve with a retreating piston in a cylinder useing standard air flow.
BTW YES IM fully aware its really atmospheric pressure that fills the cylinders when pressure drops in the cylinder

Sonix

iTrader: (1)

Ah, alright, fair enough.

TraviZ

iTrader: (2)

I bought the kit off an ebay seller, it was an all forged eagle assembly with my choice of JE/SRP pistons. And SRP sells a -23cc dished forged piston for 383's with 6" rods, just as I have. Check out the other options they have.

http://www.jepistons.com/cat/je/auto...y_23_inv.shtml

part number 131631 is for 5.7" rods and a 64cc head would net you 8.5cr aprox.
I bought part number 170817 for my 6" rods and my 75cc heads get me my cr I want.

Guest

I just stumbled across this today, looking for something totally different... so I thought I'd post it.
http://www.tmossporting.com/tabid/1805/Default.aspx

"What I am saying here is that port velocity is good, but too much will limit power - completely independent of CFM numbers. "

Among other factors already mentioned. I think his engine has gone past the 195cc range for multiple reasons, no sense saddling the engine down with small heads. You cant get too wrapped up in trying to quantify every aspect of a running engine or you'll just bury yourself. All of the things we generally refer to like compression ratio, head flow, etc... thats all static. An engine is NOT static, its dynamic. Static numbers are used to gauge differences and make generalizations but they should not be used as the end all be all for results.

customblackbird

iTrader: (15)

hmm i just went through all thos calculations on that site to figure out what my patriot 195cc heads where gona do on my motor.

383
S=stroke=3.75"
B=Bore=4.030" squared = 16.2409

pratriot intake ports 2"x1.25"=2.5sq/in
i chose Kn= 184136 endurance race roller cam since mines gona be a roller cam and not a falt tappet
RPM= (2.5 x 184136)/(3.75 x 16.2409)= 7558.53 thats kinda high :/

now...

CA= (.00353 x 7558 x 3.75 x 16.2409) / 690= 2.3549

now i have CA and RPM so now to plug it into the last equation
limiting port velocity
LPV=( .00353 x 7558.53 x 3.75 x 16.2409) / 2.3549 = 690FPS!!!

i plugged these #s in and i get a max rpm of 7558 rpms.... thats really high in a 383, then i get 690fps limiting velocity speed.... when 250-320 is good and 600 is the max lol i just wasted an hour tryin to figure this out

wat did i do wrong?
the motor is a 383 with 9.0 comp, 195cc patriots that flow 260/270cfm at .5/.6 lift
cam is XFI280, 230/236 .567/.571 lift 113 lobe
and a ported HSR, 58mm TB i kno i wont be pullin 7000rpms with this setup but i think it'll be around 5500-6000 peak

grumpyvette

"wat did i do wrong?"

ITS A COMON MISCONCEPTION, ITS NOT the port area at the enterance , you need to use in the calcs, ITS the MINIMAL port cross section at the SMALLEST point in the port, usually near the pushrod area.
LIKE a funnel, its not the largest part of the opening but the smallest thats the restriction to flow

customblackbird

iTrader: (15)

ahhhhhhhhhh!

the pushrod or the valve stem area? so then how would i measure that lol? i mean thats a tough place to get to when the heads assembled. i did notice that patriot did alot of work to the head tho. 5 angle valve job, CNC bowl blended, and when i looked in the intake and exhust ports they ported them all around the valve stems up about 3/8 the length of the runners... i wanted to hug someone

grumpyvette

http://www.harborfreight.com/cpi/cta...temnumber=5649


http://cgi.ebay.com/CEJ-Sweg-Sweden-...QQcmdZViewItem

TraviZ

iTrader: (2)

for your cross sectional area on your heads, try a 1.93. and post what your new results are. seems to be a common, or average number for 195cc heads.

I went ahead and did the math for you, (i'm a little bored). your new rpm I came up with was about 5825rpm, makes more sense for a 383.

customblackbird

iTrader: (15)

haha thanks for doing the work, my brain hurts.

that does seem better for a 383, and my cam is 2000-6000 with the XFI280. and the HSR flows to 6000 on a 350 so with my porting i should be ok i think.

i woul dlike to look into those measurers just to be certain.