DarkblueTA

Here is what is going on. A few of us Vegas people have rearmounts on our cars. We either already had LT headers or swapped out the stockers for aftermarket LTs/shorties.

What I would like to know is what kind of exhaust do you have(i.e. stock manifolds? long tubes(type)? type of ypipe(stock/etc)?)

Just incase you're wondering why I'm asking....

car 1. (my car) coated headers/painted Ypipe, drives like an na car(doesn't really boost very well (2# in 1st...3# in 2nd/3rd and touches 5# in 4th. Seriously drives like an N/A car)).

car 2. Zombies, bare stainless headers, same as yours, boost comes up slower, and peaks at 13, he tried everything.

car 3. Jon's car, stock exhuast, makes boost super fast, sky is the limit.

car 3. Jon's car again this time coated edelbrocks, makes no boost...but is a stock cam

car 4. oem bottom, good / best heads, coated jet hots, makes boost real fast.

His are the only ones that are ceramic coated and has an 81 housing like yours, (67) but the exhuast is the same as yours, a p trim 81. He can make 15 in first gear when it had a 6 speed even, it would hit boost so hard in third on the freeway it would turn the car sideways spinning the tires at 80 mph.


Any help input on your exhaust system types would be great. Thanks in advance!

smoke20

iTrader: (2)

i have jet hot headers and ORY 3 inch all the way to the turbo, by turbo hits boost at 5.5 - 6 quickly from a launch. however because i have a .96 AR at hwy speeds it takes some time for the boost to pick up. STS is sending me an .81 AR and i should spool boost quickly all the time.

solobaric

iTrader: (5)

subscribing!

LastBlack02SS

iTrader: (21)

i had Pacesetters and tsp catted Y. Switched back to stockers for clearance and boost built quicker. They retain heat better.

longrange4u

iTrader: (2)

Ohhh good thread... me and Zombie have talked about this some. I am running manifolds... and intend on the new build to stay with them (gonna do a little porting and then ceramic coat them)... I build boost NLT 3200 RPM everytime.

Zombie

iTrader: (2)

My SLP long tubes and y-pipe are off the car right now. Stock exhaust is going back on. It will be nice to have some ground clearance again. SLP y-pipe = junk.

Theory is ucoated headers have way more surface area and radiate too much heat from the exhaust.

I'll post up my results as soon as the car is back up and running.

So far we have 3 cars with uncoated/non ceramic headers that make boost poorly, but we also have 2 cars with coated headers/stock exhaust that make boost very fast.

navymitch12

iTrader: (1)

so cats or now cats with the stock exhaust? i am installing my kit now and my exhaust is 100% stock..should i dump the cats or keep them?

gametech

iTrader: (1)

Dumping the cats made mine spool slightly faster, but it makes the exhaust noticeably louder and enhances the somewhat undesirable raspy sound at certain rpm's.

navymitch12

iTrader: (1)

what would i be looking at for power gains with and w/o the cats

longrange4u

iTrader: (2)

I dont have cats... I couldnt keep them with a 2-step... something about dumping raw fuel on red hot ceramic...

navymitch12

iTrader: (1)

yea that sounds bad..but really with the stock exhaust how "bad" is it to have the cats? i will get them removed if i am gonna lose a good amount of spool time, and anything over like 15-20hp.....but if its only gonna be a small amount i will be ok with it...for now

longrange4u

iTrader: (2)

Well you see my numbers.. I dont think that the cats really gain or loose anything for you if they are flowing good. You just cant use a 2-step with cats.

navymitch12

iTrader: (1)

well i hope you are right!

Zombie

iTrader: (2)

i'd be concerned about a piece of cat breaking off. Might want to hollow them out.

I had a small piece of piston go through my turbo and much the turbine wheel, that wasn't cheap, 300 for the wheel + labor + shipping =

Turns out the piece was from floating the valves on the 918 springs, 3 pistons with lots of contact when the old motor came out.

enginjoe

iTrader: (11)

Ok. I have a STS T67/w .81 A/R and the spool is slow, but I think understandably so. I have full boost at about 4000rpm. Mitigating factors are that I have 4.11s, Jet Hot LTs, Jet Hot y-pipe, no cats and what's left of the I-pipe from the SLP DD exhaust. I wrapped the Y-pipe with header wrap to keep it from radiating the charge pipe as well as put a blanket on the charge pipe where it runs along next to the header. I don't know if it helps because my IATs are through the roof on high boost (8psi) and above that they are dangerous even with my meth injection. I think power is good at 8psi because I ran almost 120mph in the 1/4 @ 3772lbs race weight (et was a crappy 12.59 cause I can't drive, but that's another story).

So, you guys are getting better spool on the stock manifolds? What about power? I wouldn't mind swapping a couple of horses for quicker spool and less heat under the hood.

gtomiami

I am running stock manifolds with cats. My car accelerates hard with no noticable turbo lag. At the 2-3 shift the tires break loose and shreek. At highway speeds it launches like it was catapaulted. Just perfect to get around traffic on those scary two lane Florida backroads. Had the STS on for about 15 months. No complaints, except from ricers and ford guys.

Whenever I call the STS tech guys, they warn me not to run headers. I have been considering the high flow cats. I usually run 5 lbs boost, but have a programmable boost controller. I run intercooler,42lbers, upgraded pump, and gt67 turbo.

Lately I've been collecting new parts to go for higher boost (ported/coated chamber 6.0 heads, cam, forged internals 347motor, alkycontrol). I've been trying to find the time to get in some dyno runs, and a pass or two at Moroso. So I apologize in advance for not documenting this cars performance. Still a work in progress.

BJM

iTrader: (1)

From my Turbo Buick days I recall everyone saying not to change the factory headers, mostly because you would slow down. The traditional header designs for N/A cars seems to hurt turbo motors. You have a much larger internal volume in a long header than a manifold, more to fill. You also slow the flow down with larger pipes. This was all true for conventional turbos near the motor but I am surprised it affects the rear mounted STS guys.

Scott(382-$T$)

iTrader: (2)

Wow guys! My car spools very quickly. When i get home next week for 2 weeks of vacation, i want to see how low in the 10's she will run. I have SLP LT's with no cats on mine. It spools instantaneously! My car is one of the project cars @ EPP

hissin'98

iTrader: (1)

Wow, this thread is great. It has me thinking now about how I want to go about doing my exhaust. I'm still running the stock system although I have done 6.0 heads with a mild 222 comp cam. I was seriously considering LT's but now I think I might look for a set of newer manifolds of an ls6. It makes sense that there is more volume to fill so I might settle for manifolds and straight 3in to the turbo. My car spools instant as well so I don't want to spend hundreds on headers and take a chance of hurting the performance.

fletchls1

iTrader: (10)

Same here...Its hard to keep an eye on both gauges at the same time while still watching the road, but I am seeing around 10psi around 4000rpm. Also running SLP LT and their Y-pipe w/o cats. I still have my 4.10's in but I am switching them out the beginning of next week. Hopefully it will be for the best.
FYI- This is not an sts, but a home built rearmount