LQ9CHEVELLE

iTrader: (2)

Since a engine is a glorified air pump, and boost is really a byproduct of induction restriction VS airflow......would it be worth it to ditch my stock 317 heads and replace them with a set of CNC'd L92 heads? My goal is to make 600rwhp 91 octane pump gas, on a lq4 turbocharged, with the biggest Air-Air intercooler I can fit. If I can get away with less boost and increased aiflow (via larger heads) to meet this goal, Im all for it. I would prefer to not have to run methanol injection to acheive 600rwhp on pump gas if I dont need to. How much extra HP would ported L92's add, assuming all other aspects of the build were the same? Another question would be, how many lbs of boost more would it take my LQ4 with stock 317's to acheive the same rwhp as ported L92's. And yet another question.....with 9.5:1 compression with a A2A intercooler, how many LBS of boost can be run before methanol injection becomes necessary on california crappy pump gas? I know these questions require trial and error and that everybodys combos are a little different, im just trying to get a ballpark idea before I go dump $$$$$$ on my intake setup, and possibly a set of heads for my build.

tomz28

iTrader: (20)

id stay with the 317s and spend the money on a shortblock or some AFRs
i hear the L92s have a thin deck.
and like most you are going to want more so just get some really good heads and be done with it
ive also made over 650 rwhp with stock 317s

Mr.Big

761rwhp with WCCH 317's here... Your goal is VERY attainable...

1320

iTrader: (6)

Really depends on budget. I would run l92's no question if the budget was there. Here

https://ls1tech.com/forums/forced-in...o-results.html

If it had 317's, it would probably mak ein the area of 25% less power. With a goal of only 600, 317's are fine......but if you want it easy, or want more....then l92's would be the ticket.

600 rwhp = a 347 8.5 to 1, z06 cam, 317's, ls6 intake, 60's, and about 12.5 psi with two 25 year old gn turbos.....

Mr.Big

I would be very close to your numbers if I cranked mine up to 13.8lbs of boost, I highly doubt your guess of a 25% power loss is accurate, the L92/LS3 heads are the BOMB, but they are not worth the extra $1500 to me, when you consider the extra cost of the heads and intake... but that's just my opinion from my experiences...
to the O.P. your current goal, and your future goals up to 900rwhp will be attainable with 317's if setup correctly...

1320

iTrader: (6)

Mr big, how big is your engine and is it a 6 speed?

Your wcch 317's are far cry from stock 317's and they are about 1600$.

Stock 317's flow around 230 cfm and wcch 317's flow around 310 cfm. l92's around 340 cfm. The link I posted was throung a th400....and 4000 stall, so you can add around 15-20% more if your comparing yours and yours is a 6 speed.

The real question is, is teh op even building a 4.00 bore engine?

NicD

iTrader: (7)

25% more horsepower with L92s? Damn, pass what you are smoking over this way I want some!

engineermike

NO

camarols1

iTrader: (17)

The 317's will support 600whp all day.
You can just use what you have and spend the money elsewhere.
The addition of the L92's will not be worth the $$$ for only a 600whp goal.

1320

iTrader: (6)

ok, who here has stock 317's......and who here has a dyno over 600? The link I posted showed 829 hp I think......at what 13.5 psi? Through the auto......so the only stock 317 headed fi car I know is zombies......I built it, and at 13.5 psi through his 400 it would dyno in the 500's.....

tomz28

iTrader: (20)

all i have on my 317s heads are dual spring.

NicD

iTrader: (7)

I know of two local turbo cars that have stock 317s with springs and are making in excess of 600 rwhp. Not sure why that question would even be asked, like it's a big deal or special or something?

Bryan @ Speed Inc.

iTrader: (19)

This guy has L92's ported by west coast cylinder heads... i wouldn't exactly call that working on a budget.

i think the guy wants info about stock vs stock.

we've had stock l92's and l76 intake on a 408 motor with a tiny 225/225 cam and twin PT-61's...

with boost in the upper teens made over 900rwhp....

veee8

iTrader: (40)

The stock 317's should get you to your 600 hp goal.
My L92's are stage 2 cnc WCCH's, with a GM single plane/elbow.

LQ9CHEVELLE

iTrader: (2)

I didn't mean boost was a byproduct, the point that I was getting at is that boost dosent equal airflow. Boost is a measurable pressure, created by cramming more air into your motor than it would naturally consume while running under natural atmospheric pressure. Airflow makes power, and obviously boost will pack more air (0xygen) into a given space...but boost itself is not a measure of airflow....it is a measure of pressure, which is created by restriction to the air the turbo is trying to pass through your motor. Eventually you reach a point where elevated boost levels are creating too much heat to justify pushing it any farther, especially using limited octane (pump gas). Hence.....going with a bigger head and increasing the air flow potential of the engine. Same airflow (not boost) from the turbo would result in more power, cooler and denser intake charge due to less boost, due to less restriction in the induction system and more effecient use of what the turbo is providing. I am trying to decide if the increased head efficency of a L92 is worth spending the money for, if im only shooting to make 600rwhp on pump, with no methanol. THATS what I ment

LQ9CHEVELLE

iTrader: (2)

Not asking to be special, cute, funny or amusing. Asking because I live in california, have shitty 91 octane at best pump gas, DONT want to run meth injection, and want it to make 600rwhp on a safe, conservative, drive anywhere under any conditions tune. There are a ton of cars that make upwards of 650-700 with meth injection, limited timing on pump gas, and "all planets must be aligned to avoid KR" tunes on stock 317's....and thats fine, just not for what I want to do. I know 600hp is not a big deal with a 6.0 boosted...but my question is valid for my intention and concerns. Just would rather build it once than twice, and start with the right parts to begin with. thats all

LQ9CHEVELLE

iTrader: (2)

Thanks for the info guys

BuffJoeyD

iTrader: (2)

You are really throwing off my understanding of fluid dynamics -

If you think the planets have to be in allignment to use meth 317s and stay off KR then I think you might wanna start over with ur understanding.

I dont think you can gain any additional understanding from anything anyone can tell you at this point other than your original question is silly.

l92 is better than 317-

When you plan your budget you should get an idea of what parts you will buy and what you will end up with. You either have the money for better heads and an intake or u dont.

LQ9CHEVELLE

iTrader: (2)

91 pump gas
No Meth
600rwhp
safe tune

This is my goal, was simply asking if L92's should be used, or if the 317's will suffice

Nothing to do with my finances....has to do with right choices for my end result

If I need better heads to do this, ill buy them....thats why im asking if i need them or not.

You all have experience and knowledge, and I value all of your opinions

why the hostility?

LQ9CHEVELLE

iTrader: (2)

For the record - not trying to be hostile...just want advice and suggestions
I dont want to be the smart *** that gets banned or starts stupid arguments....I just want to learn, share knowledge and put together something nice.
I know better parts = $$$$
I have no prob buying the better parts IF they are needed
Was just trying to decide IF spending the extra $$$$ was necessary
Im not broke...but im not into spending money when its definetly not needed...Im sure anyone can understand that
Thanks again for everyones help