Since when did the boost taper off on the TT. Stock boost is 8.5 lbs on the TT. Boost tapers on the S/T only and they designed it like that or are we going to start this all over again. You can expect around 400 rwhp with a good exhaust and test pipes out of the box with a 93 octane map. Plus your tune will still be safe.

 

Nobody is getting 400whp out of the box (TT) even with a true dual exhuast system. The boost on this car would run to 8psi, and then drop to 6psi by redline.

Still waiting for somone to post a boost graph...showing constant boost to redline on the TT kit.

 

Your wrong I have APS TT with stillen exhaust xerd test pipes 93 oct map. 397 rwhp was my last dyno 90 + degrees temp and humidity. It was done on a dyno jet at petit racing in florida. Oh and my boost doesn't taper off when I watch my gauge it holds 8.5 lbs to redline. I would have hit 400 except for the weather and a A/F of 10.0.

 

You are a lucky one! Can I see your boost chart?

Based on my experience, and the experience of shops willing to talk about the issue, the base APS map is not making 400whp. IF this kit was actually making 8psi or so consistently to redline, then 400whp is easily doable. The power loss is coming from the boost loss, and just partly from the tune.

 

Mine didnt loose boost either... *shrugs* btw whats the number to trq freaks for the actuators and does the unichip work ok with them? or is everyone getting a boost controller?

 

If you are looking at a boost gauge, you may not notice the drop...we didnt either. Log it on a dyno.....its a 2psi drop. That's why I am curious if someone else can post a dyno chart with the boost mapped on it.

 

hm...a lot of variations in facts here...this is what I'm talking about lol...

It's all good. The more discussion the better.

 

a lot of shops dont wish to talk about...and a lot of customers spent a lot of money on these kits...and also dont want to talk about it. THere are some fixes, but none of them are cheap...once the turbos are installed on the car. I still feel the APS kit is the best engineered kit on the market, out of the box....but it could still use some improvements.

 

Sharif...could it be something simple due to the 287hp engine? In stock form, the power kind of drops off at high rpms too. Would the exhast cam timing in the rev-up engine fix that?

 

^ that is exactly why i think my boost didnt drop off.. because i have a rev up engine..

 

The car in question makes power nearly all the way to redline...just not as much due to the 2psi boost drop. I have no doubt it would make 380-400whp if the boost remained at 8psi or so.

 

ic...anything I should look out for during my install? any heads up? thanx.

 

I would gladly show it to you but I don't have one.It's funny this is the 1st time I've seen anybody say that there boost is tapering off on a TT. If anything a simple tune will solve that problem. My installer is finishing there dyno install this week. I have to check and see if they will be able to map boost as well.

 

A simple tune would be nice if everyone had a APS shop close to them.

 

Cap, the boost issue is not in the tune. On this particular car, we completely removed the Unichip, and its boost control equipment, and ran an EU, and the state of art Blitz SBC-Id....still loosing boost, and this with a Crawford plenum and true dual 2.5 inch custom exhuast system, and test pipes.

We still got 400whp out of the car....but at just 6.5psi at redline. Would easily have been 440whp if it could hold the boost!

 

Excellent Sharif...

I wonder if a computer model could be created to display a finite number of
parameters.. Exhaust flow, Boost, Timing, ecetera... Related to Whp and Tourque. Your thoughts?

Cheers Amy -

There are probably enough dyno tests to fill the initial data base.

 

That goes for any engine management. If thats an issue then buy what you can have tuned properly.

 

I was initially thinking that APS programmed their unichip to run off the boost at redline to lighten the load in the stock block for mass production purposes, and to not shoot for a dyno queen, but more flat (usable) power curve, if your information was correct. But if you have removed all that and ran an EU, it kind of sounds like a boost leak occurring ONLY at high rpms...which does not really make sense either...

What you said about the boost actuators makes sense, but would swapping it with another APS boost actuator work? The ones for higher boost over 12psi. Then more money is down the drain right away for building up the block to adapt the boost......

 

I can vouch for the dyno results I was there dynoing mine as well that day and it was hot as hell.

 

nitrouz this is the 1st time I have heard about this happing. My boost holds to redline. I have a boost gauge that goes to 20 lbs I would see a 2 lb drop on the gauge. Ocne he removed everything from the kit you change the way it was designed. My installer has done 3 other kits and they don't loose boost either. This all reminds me of the aps vs tn s/t arguments that went on when they were 1 st released. I'm sure when you install your kit it will be fine out of the box.