383s and the Cyl head/Cfm need to feed them
Registered User
Joined: Jun 2002
Posts: 2,456
From: sarasota, fl
heres an interesting thought
as someone mentioned.........275cfm (the typical max ported lt1 head) should be good for about 575fwhp, which should be about 480-500 rwhp.
however, that same head, with a stock lt1 intake attached, flows less than 230.
that equates to about 475fwhp.......or 390-410 rwhp....
that just happens to be where most LT1 heads/cam or 383 engines ive seen on this forum end up dynoing.
correct me if im wrong, but that pretty much proves the intake is whats limiting the power
as someone mentioned.........275cfm (the typical max ported lt1 head) should be good for about 575fwhp, which should be about 480-500 rwhp.
however, that same head, with a stock lt1 intake attached, flows less than 230.
that equates to about 475fwhp.......or 390-410 rwhp....
that just happens to be where most LT1 heads/cam or 383 engines ive seen on this forum end up dynoing.
correct me if im wrong, but that pretty much proves the intake is whats limiting the power
Registered User
Joined: Jul 2000
Posts: 2,735
From: Buffalo, NY
1racerdude knows what he's talking about. Now I know this has come up a thousand times before but...Say you have LT4 heads that flow 275 cfm, you lose 8% with the BRE intake, you have a 58mm or Monoblade TB capable of flowing 1000cfm plus, and a CAI. Does the stock screened MAF become a huge restriction than?
Found this from another thread....
(F-body) 3.5" MAF w/ screen = 759 cfm
(F-body) 3.5" MAF w/o screen = 979 cfm
Found this from another thread....
(F-body) 3.5" MAF w/ screen = 759 cfm
(F-body) 3.5" MAF w/o screen = 979 cfm
Registered User
Joined: Jan 1999
Posts: 884
From: I reached back like a pimp and smacked that LS1....
FWIW, when I had a naturally aspirated 383 it made 452rwhp 416rwtq with GTP stage 3 LT1 heads, cam motion 252/252 .600 lift solid roller and LT1 intake manifold.
I was quoted 294cfm @.600 by GTP, but I never had them flow tested independently.
I was quoted 294cfm @.600 by GTP, but I never had them flow tested independently.
Banned
Joined: May 2003
Posts: 6,661
From: LA (lower Alabama)
MAF
According to PCMFORLESS the stock un screened MAF WITH ported ends is the way to go.A larger one according to them makes very little difference and creates tuning issues.Rember about your CAI and filter flow and the TB.It's all a system.
INTMD 8,
300Cfm will get you 617FWHP,and ALL your HP is from the filter to the piston.The better it is the bigger the HP&TQ number's
INTMD 8,
300Cfm will get you 617FWHP,and ALL your HP is from the filter to the piston.The better it is the bigger the HP&TQ number's
Last edited by 1racerdude; Jun 27, 2004 at 04:55 PM.
Registered User
Joined: Jan 1999
Posts: 884
From: I reached back like a pimp and smacked that LS1....
Re: MAF
Originally posted by 1racerdude
According to PCMFORLESS the stock un screened MAF WITH ported ends is the way to go.
According to PCMFORLESS the stock un screened MAF WITH ported ends is the way to go.
I'm suprised they would say that. I've found that maf's with "ported" ends are horribly inconsistent.
I would rather use a stock LS1 corvette 85mm maf and transpose the MAF table.
Banned
Joined: May 2003
Posts: 6,661
From: LA (lower Alabama)
Well I will let you know.I am going to try a stock and a PRO M 85MM as soon as I get time to take it to the dyno and see.
Which ever one works the best is going to stay on.
Call Bryan and find out,he told me ther were NO issues with the stock one SOOOOOOOO.He has the computer experience not me.
If you are using the standard cone K&N it flows 700CFM.
Which ever one works the best is going to stay on.
Call Bryan and find out,he told me ther were NO issues with the stock one SOOOOOOOO.He has the computer experience not me.
If you are using the standard cone K&N it flows 700CFM.
Registered User
Joined: Dec 2002
Posts: 241
From: TN
I will be posting track numbers soon. also mabe dyno numbers. I have a 383 with ported stock lt1 heads and intake. I am hoping to make it to the 9s with the spray. I have not heard of may people going to the 9s with the stock lt1 head casting ported.
Thread Starter
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Joined: Sep 2002
Posts: 1,942
From: kitchener/Ontario
1racerdude Steve Quinn is one that comes to mine 9.71ET
With a 383 set up right,700FWHP is very doable with EFI.ALL MOTOR---
Steve allso has LT1 heads, Is he doing somthing know one no's....
With a 383 set up right,700FWHP is very doable with EFI.ALL MOTOR---
Steve allso has LT1 heads, Is he doing somthing know one no's....
Registered User
Joined: Jun 2002
Posts: 2,456
From: sarasota, fl
Originally posted by Schurters LT1
Steve allso has LT1 heads, Is he doing somthing know one no's....
Steve allso has LT1 heads, Is he doing somthing know one no's....
he has converted to a single plane intake though.
steve quinn has made his own custom modified LTX intake.
he actually has one for sale here
Last edited by got_hp?; Jun 28, 2004 at 07:57 AM.
Registered User
Joined: Nov 2001
Posts: 2,985
From: In a house by the bay
I believe our pal Joe is running AFR 227's.
Not here nor there cause neither Steve or Joe built their cars for picking up the groceries and/or getting them back and forth to work. So keep that in mind when you start looking at ET and considering parts for your own ride.
WRT 350 vs 383 and cylinder heads. The intake is part of the equation yes, but the cylinder head port area is what's gonna make or break the combination. A port that reaches a limiting velocity at 6500 rpm on a 350 will reach similar speeds at 6000 rpm on a 383. Cam all you want... the cylinder head can only do so much and you keep chasing the better numbers....
-Mindgame
Not here nor there cause neither Steve or Joe built their cars for picking up the groceries and/or getting them back and forth to work. So keep that in mind when you start looking at ET and considering parts for your own ride.
WRT 350 vs 383 and cylinder heads. The intake is part of the equation yes, but the cylinder head port area is what's gonna make or break the combination. A port that reaches a limiting velocity at 6500 rpm on a 350 will reach similar speeds at 6000 rpm on a 383. Cam all you want... the cylinder head can only do so much and you keep chasing the better numbers....
-Mindgame
Registered User
Joined: Feb 2003
Posts: 641
From: St. Charles, Il
Originally posted by brain
racerdude, I am still learning, so don't think I was correcting you. I am curious though. Why do most people, well at least on this board, say that a set of 215 AFRs would be too big for a 350? Seems if 240 or larger is fine on a 383, then 215s would work perfect on a 350. I understand that rpm plays a role as well, but not many street motors run 8500, and yeah, I would consider a 302 turning 8500 to be a bit lazy on the low end, as it would probably start to pull good at 4000 or 4500. Then again, if it were geared properly, you'd never know.
racerdude, I am still learning, so don't think I was correcting you. I am curious though. Why do most people, well at least on this board, say that a set of 215 AFRs would be too big for a 350? Seems if 240 or larger is fine on a 383, then 215s would work perfect on a 350. I understand that rpm plays a role as well, but not many street motors run 8500, and yeah, I would consider a 302 turning 8500 to be a bit lazy on the low end, as it would probably start to pull good at 4000 or 4500. Then again, if it were geared properly, you'd never know.
LT-1 (170CC) heads are for near stock applications, if you rase your cubes, or raise your redline, you need to go bigger.
LT-4 (190CC) heads work great with like a 355 at like 6500 or a budget 383 near stock rpm band.
AFR 215CCs are the popular pic for a 383 thats a street strip car Probibly overkill on a 355 unless you are going 7000+
Remember, if you were to throw the 215s on a stock bottom end your port velocity would suck at low rpms. But if you are running a high stall anyway you may be ok.