sujomatt

iTrader: (7)

I know people are telling me Stock 99 Z28 Headers and 2.5" ORY would be the best choice... But I was planning on running 12 PSI since I have low compression heads, chromemolly pushrods, etc. Would that idea still stand true knowing this? Will I lose power if I go down on pipe sizing? I was going to heatwrap everything to the bottom of the ypipe, I currently have LT's and ORY. I am sure this may have been beat to death before but I figure it may be a bit more unique in this case. Thanks!

ps. i keep seeing builds with LTs and 2.5" ORY, or just plain LTs and 3" ORY.. can anyone fill me in on performance?

Blackbird

people are right.

sujomatt

iTrader: (7)

Care to elaborate? lol

If I have that much flow trying to trickle through 2.5" piping.. will i still see good numbers? Trying to wrap my head around this because I am about to start ordering. Thanks

Have you tried LTs and found that it was so laggy it wasn't worth it? When was Full boost with LTs vs stock headers, etc.?

vandal0-0

iTrader: (3)

I agree,I run stock manifolds with cat delete pipes and stock y-pipe on a 408.Everything wrapped and will be around 15 to 18lbs of boost.I had LT's and 3" ORY everything wrapped except LT's and It was pretty laggy.If you wrap the LT's It will help but I would just do the manifolds.Look at Zombies Rearmount Saga post.

sujomatt

iTrader: (7)

Vandal did u see a different in power when u swapped though? Just curious

vandal0-0

iTrader: (3)

I just noticed your running a 67mm.When I had my 67 on my car It wasn't bad with the LT's and that was with the stock motor and cam.But make sure you wrap them.

sujomatt

iTrader: (7)

Awesome, thanks dude

vandal0-0

iTrader: (3)

The stock manifolds will just make It spool faster which will make your power come In faster of course.But for makeing more power I cant say because I have changed my whole set up since I put the stock manifolds on.

vandal0-0

iTrader: (3)

No problem good luck.

Blackbird

also just read any and all of zombies threads to ease your mind.

he has a 9 second rear mount and he uses stock manifolds.

sujomatt

iTrader: (7)

tried doing a thread search for zombie, not seeing it :X

vandal0-0

iTrader: (3)

Zombie
10 Second Club




Trader Rating: 2
Join Date: May 2004
Location: Las Vegas
Posts: 1,860
Switched from headers to manifolds with rear mount turbo (results inside)

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Had two changes done to my car recently and recieved it back yesterday. Converter got swapped for a much tighter one, car feels almost like a stock auto now but will foot brake to 2700, it's very nice.

The other change was my switch from SLP long tubes back to stock exhaust. With SLP long tubes I could set the wastegate to stay closed and it would struggle to make 13psi. After the swap back to the stock exhaust it comes up to full boost of 15psi at 50% throttle (verified by loggin). It's a HUGE difference. The SLP LT's suck very much, not just for a turbo application but because of ground clearance. Sold my old ones for $200.

The wastegate actually opens and makes noise now, car feels great. Only major change left is to swap to 2.75 gears and the car will be just about perfect.

Another thing that was done to my exhaust was it was painted with high temp white paint. Why white, because white reflects the heat.
We were told by my friends father (literally a rocket scientist LOL) to paint the pipes to help them retain exhaust energy. The results on a quick measurement he made at idle was very impressive. At the primary tube of a header his idle temp went down 45 degrees (from 530 to 485) from about 2 square inches of white paint only applied to the top of the header tube. If the heat isn't being radiated off the header then it's staying in the pipe. I've played around with charles's law calculations (p1/t1 = p2/t2, i'm a nerd, so sue me) and found that if you have 15 psi of exhaust pressure at 800 degrees before the turbo, raising that temp to 900 degrees will give you 17.3, a 2.3psi increase! Raise the temp to 1000 degrees and it's now 19.7 psi! Shows you how important it is to keep the heat in the exhaust. Long tubes + ehxuast have over 2 times the surface area of stock exhaust.

He's doing some more experiments with header wrap and painting the ehxaust to see if he can get the headers to work as good as or better than his stock manifolds did.

Zombie

iTrader: (2)

No 9's yet, workin on it this year, got some changes coming this month from Forced Inductions. Still an 80mm turbo though. I'll make two rediculously long detailed posts of how the car drives with it and how it performs at the track when it's done.

P.S. Ceramic coated stock manifolds F T W! <-- what I run now.

vandal0-0

iTrader: (3)

Now what size you going with.