Stock LS6 exhaust manifolds with blown 427 LSx...
07-10-2007, 09:43 AM
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Stock LS6 exhaust manifolds with blown 427 LSx... ...well, I guess my question below seems strange, but because of minor budget issues, I'm planning to stick with my current LS6 exhaust manifolds and cats, while my new engine will be LS7-based and with CNC-ported Edelbrock heads and T-Trim Vortech supercharger system from A&A Corvette. Intake is my existing LS6-based and injectors are 60 lbs/hr, compression ratio is 9.8:1 and camshaft is 228/232 with 115 LSA.
So, would using stock exhaust manifolds increase back-pressure so that exhaust temperatures would be too high? Of course using long-tube headers is the right way to go and I'll do that in future, but not now, and that's why I'm asking.
So, would using stock exhaust manifolds increase back-pressure so that exhaust temperatures would be too high? Of course using long-tube headers is the right way to go and I'll do that in future, but not now, and that's why I'm asking.
07-10-2007, 11:12 AM
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Originally Posted by Slowhawk
I say let the car sit until you can do it right. 
"Everybody wants 1000hp with a 400hp budget"
Would you guys please just give a feedback or opinion if stock manifolds are problem or not...
What I've understood, there are some STS turbos using stock manifolds with pretty good rwhp. And similarly, some say that while long tubes will provide 20-30 rwhp in supercharged & forged 346, it isn't actually a problem to run with stock manifold in these engines (but now I have 427).
Ps: I don't speak or write native english, so if there's something hidden between lines, I didn't put it there intentionally.
Last edited by Pekka_Perkeles; 07-10-2007 at 11:18 AM.
07-10-2007, 11:49 AM
#6
Originally Posted by Pekka_Perkeles
Would you guys please just give a feedback or opinion if stock manifolds are problem or not...
.
So,yes I would say stock manifolds are a problem
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07-10-2007, 12:42 PM
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Originally Posted by MIGHTYMOUSE
you are flowing like 23% more air than a stock motor on displacement only. the manifolds would be a problem even if you were not supercharged.
But how come superchargers and nitrous are still ok quite often with stock LS6 manifolds and stock LS6 displacement?
What I'm trying to understand is where's the limit with stock manifolds and stock cats and stock cat-backs? Surely the limit is somewhere, but when does it become more a problem than a limitation?
07-10-2007, 01:02 PM
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Originally Posted by Pekka_Perkeles
...well, I guess my question below seems strange, but because of minor budget issues, I'm planning to stick with my current LS6 exhaust manifolds and cats, while my new engine will be LS7-based and with CNC-ported Edelbrock heads and T-Trim Vortech supercharger system from A&A Corvette. Intake is my existing LS6-based and injectors are 60 lbs/hr, compression ratio is 9.8:1 and camshaft is 228/232 with 115 LSA.
So, would using stock exhaust manifolds increase back-pressure so that exhaust temperatures would be too high? Of course using long-tube headers is the right way to go and I'll do that in future, but not now, and that's why I'm asking.
So, would using stock exhaust manifolds increase back-pressure so that exhaust temperatures would be too high? Of course using long-tube headers is the right way to go and I'll do that in future, but not now, and that's why I'm asking.
07-10-2007, 04:00 PM
#10
just run em, look what people used to run on big blocks and the like. Its definately not going to hurt anything, but you will see a large power increase with the headers. Like 40-50rwhp. Also will need to get it re-tuned. It gets old when everyones opinions are " youll blow up the earth if you try to do that!", know what i mean? Just get the car together and enjoy it till you can afford the headers, no big deal. Also the limit of the stock exhaust components is when you stop making any more power, so probably around 600-650whp. Is it the right way to make 600rwhp? no. can it be done? absolutely.
Gary
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07-10-2007, 05:12 PM
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ok, they will be a restriction... but a physical danger to the motor? i doont think it will be. it should run fine and all but your rpm will be down and hp will be down.
07-10-2007, 05:35 PM
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I have done back to back dyno testing with headers and cast iron GTO manifolds on a blown 389 LS2 based engine. When I went from headers to cast manifolds the power did not drop off much, but the boost went up, probably from the restriction on the engine. Car has been driving boosted with cast iron for 2 years with no problem. Two Power Tour's and daily driven on the nice days. I would rather run headers, but the owner prefers the quiet engine to the HP increase. You won't hurt your engine with cast iron ex, you will just give up a little power.
Kurt
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