How do STOCK LS1 exhaust manifolds compare for the 98-02 model years??
Steve H. and I were discussing this through email and he sent me the following information: (THANKS Steve )
1998-1999: Stainless steel manifold W/EGR. 2000 only: Cast Iron manifold W/EGR. 2001-2002: Cast Iron manifold NO EGR.
So, the question: Is anything else different, such as ports, flow, etc.?
Thanks, Kevin
As an aside: What was done to the manifolds of the Tom Henry cars? (I believe they were ported, ...but) 'specifically' what was done?
Posted by 2002Z4CSS (Member # 1393) on :
I read somewhere (can't remember where) the cast iron exhaust manifolds actually flow better than the stainless ones. I can't say that statement is true or not. The tubular stainless ones from what I also heard were prone to cracking at the welds.
Posted by Cavy Dan (Member # 1352) on :
quote:Originally posted by 2002Z4CSS: I read somewhere (can't remember where) the cast iron exhaust manifolds actually flow better than the stainless ones. I can't say that statement is true or not. The tubular stainless ones from what I also heard were prone to cracking at the welds.
Thats possible...I'm not engineer, but i'd say it might be because of heat retention, or the lack thereof. But boy, do the cast iron get yucky and rusty looking!! Posted by Hawkeye (Member # 88) on :
Well if all goes well this weekend my stainless stock ones will be off. There was a discussion about this a few years ago on the SLP board.
(before the first meltdown) maybe Dave H. or Jeff Y. would have the info, they were both very active on the boards then.
Posted by Bill Mason (Member # 1807) on :
quote:Originally posted by 2002Z4CSS: I read somewhere (can't remember where) the cast iron exhaust manifolds actually flow better than the stainless ones. I can't say that statement is true or not. The tubular stainless ones from what I also heard were prone to cracking at the welds.
Hhhhmmmm.....that probably explains the slight exhasut leak sound I get from the right front from time to time when I start it up or accelerate hard.
Posted by Mike2001SS (Member # 2088) on :
The cast-iron manifolds on the 2001-2002 cars are one of the most free flowing out there next to long tubes they flow better than almost any shorty headers and give good torque thats why GM went to them. I f you change from them to anything other than a good set of long tubes you wasted your money. They are better than the 2000 back
Posted by chrisL (Member # 97) on :
pretty sure the difference between 00 and 01/02 is just minus the EGR.
Posted by Mike2001SS (Member # 2088) on :
ChristL it was advertized alot that the new cast manifolds for 2001 was to improve torque and flow along with the intake change. They raised the HP by 5 but the new manifolds and cam were to make the power band better
Posted by Mike2001SS (Member # 2088) on :
Crist here's one for you. I had a 98 SS vert with lid and opt' exaust and tuned and the best it ever did on the dybo was 292 RWHP and around 314 RWTQ I ordered the same car in 2001 except change in color. with lid and duel-duel exaust and y-pipe and tuning it dynoed 330 RWHP and 345 RWTQ. You tell me what items on the basic same motor gained 38 RWHP between the 2 cars
Posted by 380SS (Member # 2078) on :
quote: As an aside: What was done to the manifolds of the Tom Henry cars? (I believe they were ported, ...but) 'specifically' what was done?
Kevin, I've talked with Mike Carnahan from GMMG about what GMMG did to gain horsepower in my car and about getting a future phase II package installed (475 to 500HP that’s a story in itself).
We didn't go into deep discussions about the exhaust only that they were ported to flow better (how that was done is anybody's guess)He also stated that they tried shorty style headers but did not get any additional gains in the HP department so they stayed with the ported STOCK exhaust. He said they did everything they could to add horsepower and keep GM and the emission folks happy. That was their primary reason why they stayed with the "ported" stock exhaust manifolds.
Now that I think of it, I really didn't answer your "specific" question. Sorry
Posted by RagSS (Member # 1127) on :
Thanks for the feedback guys... The comment that the '01-'02 manifolds flow better seems to be what most are saying, ...so Mike, ...your comments help confirm that. Patrick, ...you've at least confirmed that the stock manifolds are indeed ported. I figure if I get an extra set (working on it), ...and take a look on the inside, ...we can take it from there. Thanks again everyone...
Kevin
Posted by Bill Mason (Member # 1807) on :
quote:Originally posted by Mike2001SS: Crist here's one for you. I had a 98 SS vert with lid and opt' exaust and tuned and the best it ever did on the dybo was 292 RWHP and around 314 RWTQ I ordered the same car in 2001 except change in color. with lid and duel-duel exaust and y-pipe and tuning it dynoed 330 RWHP and 345 RWTQ. You tell me what items on the basic same motor gained 38 RWHP between the 2 cars
Well for one thing the intakes are different. I believe the 2001 and up have the LS6 intake. Another is the fuel injectors ('98s are a little bigger).
I think the other difference is the PCM programming. The '98's run richer fuel/air mixture than later years. This is considered to be a safer setup to avoid the dreaded detonation, but costs power.
Posted by Mike2001SS (Member # 2088) on :
quote:Originally posted by Bill Mason:
quote:Originally posted by Mike2001SS: Crist here's one for you. I had a 98 SS vert with lid and opt' exaust and tuned and the best it ever did on the dybo was 292 RWHP and around 314 RWTQ I ordered the same car in 2001 except change in color. with lid and duel-duel exaust and y-pipe and tuning it dynoed 330 RWHP and 345 RWTQ. You tell me what items on the basic same motor gained 38 RWHP between the 2 cars
Well for one thing the intakes are different. I believe the 2001 and up have the LS6 intake. Another is the fuel injectors ('98s are a little bigger).
I think the other difference is the PCM programming. The '98's run richer fuel/air mixture than later years. This is considered to be a safer setup to avoid the dreaded detonation, but costs power.
Bill you are so right the 2001 and 2002 has the LS6 intake and they gained torque and midrange power from the new manifolds and a different cam.
Since that 330 RWHP dyno I did awhile after I got the car I did a cam change some porting here and there and some really good head work done with custom dyno tune and it now dynoes 410RWHP and is still running the factory cast exaust manifolds but from them back all has been changed
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