Got my APS single turbo installed and tuned by Dyno Comp in Scottsdale,AZ. I am running a JIC 3 inch single exit exhaust with that retarded reducer pipe that APS made to mate the down pipe to the stock exhaust. Well I have that reducer pipe on there and it creates a massive bottle neck in the exhaust causing my boost to taper off something fierce. I hit 10 psi just after 4500 rpm and it holds there about 100 rpm and then gradually tapers off to 5 psi at redline, in order to achieve this result we had to adjust the waste gate actuator by 4 turns. Prior to that it was hitting just under 7 psi and dropping to 5psi.
Air fuel is good at wot, right at 11.1 or 11.2 but its not real smooth. Keeping in mind that I dynoed on a Dyno Dynamics dynamometer which reads 10% lower than your typical dynojet I hit 330.1whp and 330wtq which roughly woulda been 366 on a dynojet. So now I am going to a buddy of mine to have him either fab me up a 3 inch pipe to replace the one from APS or have him cut and lengthen the exhaust pipe all the way back to the down pipe to get rid of that reducer pipe. Then we will try it again and hopefully hold the boost till redline.
All that being said I am loving all this new power and cant find any traction on these stock tires until 3rd gear. Here are pics of my run sheets and that reducer pipe I am talking about..... I dont own a scanner.

 

Every single APS ST I've seen on this car has had this same problem. Tig, beastie and now you all have had a boost peak then taper off issue.

Good luck getting everything working well.

 

thx for sharing...enjoy

 

There is a company out west that makes all kinds of custom reducers like you need......I got one made to mate my Y pipe to the stock mid pipe.

I'll see if I can find the info. I think it was "Gas Man" or something like that....

Found it....

Dr. Gas - Pro-Motorsports Inc., Sandy Utah, 801-563-1111

 

Yea I have seen that boost taper thing with everyone as well. According to bullitproof he had the same problem till he cleaned up the exhaust and now he is holding boost to redline. We couldn't find any other resaon for it to do that except that bottle neck in the system. Hopefully the issue will be resolved easily.

Thx for the info on Dr.Gas, does there happen to be a url floating around for it?

 

Pics of rest of exhaust etc? What exhaust is this?

 

congratz bro, hopefully you'll get everything worked out. post a vid when you do

 

Does a website like this one help? Click Mr. Smiley Face for the link --->

 

Google is your friend.......

http://www.drgas.com/

 

decent numbers. will be interested to see how my system does next week.

my installer is good friends with Peter from APS, so hopefully he has some tricks up his sleeve.

the car will also be dyno'd on a dynamometer.

 

Nice! Isnt FI a great feeling! Dont worry about your HP #'s. Ive learned some Dyno's post higher #'s then others.

 

Yea I am not too worried about it, I just want the turbo to operate properly for my peace of mind.


I didnt take any other pics of it yet, here is a link to it. http://www.hopupracing.com/jicmaspdety13.html