The car is equipped with an APS ST, APS Plenum, APS 2.5" TD exhaust and SP cams.

It originally dynoed on the installer's Dastek Dyno at or near 400 rWHP and 380 ft-lb of TQ. I don't have exact numbers.

I than got the car dynoed at another shop on a dynojet and it ran 294/317.

I brought it back to my installer to have it checked out and he said everything was fine.

I felt comfortable that my car was okay, but decided I needed one more dyno to be sure.

I brought it to Rob at Z Car Garage and it put down 315/340 on a dynojet.

I have attached that dyno graph here for the experts to evaluate and comment.

Rob mentioned that the car might have an exhaust leak. I assume this could be a huge contributing factor to why there is a boost drop off and why boost doesn't build until 3500 rpms. you can see the boost drop off on the street as well, but it only drops down to about 4-5 psi, rather than the 2 psi depicted in the graph.

Rob was gracious enough to perform this dyno free of charge. Hopefully the problem isn't huge and is easily resolved.

I know some members with the APS ST have had leaks on the crossover pipe. MY transmission tunnel does get nice and hot on long drives. I always put that off to heat generated by the engine, turbo, etc. Maybe that's not the case???

Any expert advice would be appreciated. I have set up an appt to have the car thoroughly checked in the next couple of weeks.

 

look behind the plenum where the crossover pipe goes, look on top of the tranny to see if there is soot on it, mine was black. im at work now, ill pm you later.

 

Can you hear an exhaust leak? What brand of boost meter are you using? Who is doing your UNICHIP tuning?

Boost building at 3500 RPM is kinda normal for the APS ST. Boost response is a little funny on that kit. At 4-5psi, your power will be low. If the duty on the APS solenoid is not set correctly (or if it took a crap), you can have that boost drop off. We struggled with boost issues and ended up using the forge actuator with the 10psi spring (we discovered it only makes 8-9 on manifold pressure). We also tuned with UTEC and the TXS boost control solenoid. We used the same cams and made 420 wheel on 9 psi through a single sided JIC/custom 3" exhaust.

Once we got the boost control issue taken care of, tuning on the UTEC was straight forward. Oh yea, we also replaced the bosch FPR with a SARD unit. There's a couple other mods. Link below. Bullitproof's car.

http://carv2.com/site/project_detail.cfm?id=443

 

will check the areas for "soot" when I get back down to LA.

to be honest, i don't really know what an exhaust leak sounds like

using defi bf-imperial gauge.

scott performance did my Unichip tuning.

thanks for the tips and suggestions. please keep them coming.

 

Maybe your hose to the WG popped off.

An exhaust leak usually sounds like a little ticking/farting noise that get worse with higher RPM.

 

I have never seen an APS single turbo hold steady boost all the way to redline. The two we did here lost half of their boost by redline. Upgraded exhaust, no exhuast, upgraded actuators, two different types of boost controllers...nothing worked.

If you can guys figure it out...let us know.

 

the other day, i dropped the exhaust, ALL of it, the only thing bolted to the turbo was the first section of downpipe with the 02 sensors in it. i gotta say the car was LOUD AS HELL...

BUT, it held boost ALOT better. it acted different than with the restrictive exhaust. with the exhaust on, and the boost controller set high, the boost shoots up to around 12 and drops to 6, which is what happened at sharifs. but with no exhaust, even with the controller set to high, it didnt make as much boost but it held the boost better. i adjusted the controller for a while, and got it set to where it would reach 10psi and hold 8.5 to 9 at redline, but it didnt start dropping until around 6200rpms. it used to start around 4500. it felt much better. it pulled longer and harder, especially on highway, high gear pulls. i actually turned it down since it was holding 9lbs. the boost response was instant and hard.

in a few weeks im gonna get a 3.5" open dump installed.

 

Even with the Blitz EBC, an upgraded actuator (10.4 psi) and the APS exhaust, mine will peak to ~ 12 - 14, but evens out to 8.5 - 9psi at redline

I feel I've done just about everything I can to get boost steadily around 12, with no success thus far. Perhaps it's the turbo's inability to maintain airflow req'd for those #'s?

 

Where are all you getting your cars tuned at? The install I did held boost all the way to redline on the out of box tune. 'maybe' dropped 1/2 lb at most. I would see 9.5 lbs peak and would see at least 9 lbs at redline. And this was with out a tune.

I am not saying what you are seeing is not legit. I just question where you all are getting your tunes done at.

With that, I don't care what anyone says, these aftermarket exhausts people are attempting to pair with this kit just don't flow. I don't care if you can run a 3" diameter ball through the entire exhaust system; the APS ST exhaust is superior

this winter blake is talking about building his motor and upping the boost on his setup. I hope he follows through with this as I am more than curious to see if he is able to hold 12+ psi to redline.

Also, Synth's car is nearing a final tune with a built motor and the APS single. I am sure he will post this type of info for us to examine.

 

because you are the supreme installer ziv, thats just how you roll.

im beginning to think it is some kind of flow issue with the turbo as well.

 

Ditto! I have done everything possible but my boost just won't hold. That's why I'm dropping the APS ST and going Greddy TT. Ziv is one of a select few who claims their kit maintains a constant boost.

 

It could be. We will have to see how synth's car comes out as well as blake's if he ends up building.

 

I will have to get a vid of blake's boost gauge during some pulls to show you what we are seeing.

My TT kit definitely tapers - though that is the way it's tuned. Not for long though - more fuel and new EMS are in the works

 

dont just watch the boost gauge, you need to log it somehow. i thought mine was holding pretty good, at least thats what it looked like, until i logged it with my zeitronix unit, and realized it dropped a lot.

 

My contention isn't the amount of drop, because I have the preload set in such a way that is has a surge of boost as I stated earlier - it is having an APS ST achieve greater than 9 - 10psi of boost at redline.

Before screwing with the preload and changing out the actuator/ebc, I was at 9psi peak, 9psi redline. It hit, it stayed, I got bored. Changed a few things, and the car is usually at or above 10psi until about 5500 rpm, and it drives great. But, I'm bored again, and looking as to how I can get this snail to flow more (consistently) at higher rpms.

To date, I haven't seen one hit great than ~9psi. Once I find someone that is hitting 11 - 12+psi consistently at redline, then I intend to emulate their setup.

 

Joe, I can make mine hit 15 right now, you probably can too, but even 12 is useless with my 19s with KDWs. i doubt youre gonna be able to get more out of this turbo. a friend of mine that builds turbos doesnt feel the turbos exhaust housing is big enough for this motor, he claims its too small and the exhaust gases are causing too much pressure to flow well. he actually hates it. hes got my spare turbo and is looking at either changing the hot side all together, or putting on a different compressor wheel. he also does some custom stuff with the exhaust turbine vanes to make it perform better. we'll see.

 

We just finished an APS ST tune on '06 G35 6MT last week. We had a tough time making less than 11-10 psi (logged on the DYNAPACK). The turbo would spike to 11 and fall to 10 by redline. That was on the 91 octane map. After siginificantly reducing the BCS duty, we managed a suprisingly smooth 9.5-9 psi all the way to redline. Actually, we couldn't make less than 9.5-9 even at the lowest BCS duties. The car made 407 wheel. Pre-load on the actuator was as outlined by APS. Exhaust was the APS dual 3" with custom 3" reverse y-pipe.

I'd have to strike it up the the exhaust. This is the largest (dual 3") we've ever used on the APS ST. BTW, the car sounds ridiculous (in a good way).

 

good, since you did it on a dynapack, you should have some boost logs, post em up.

im confused on the exhaust you used, do you mean you chopped up the APS 3" to make it fit the reverse Y?

 

I GOT IT........I GOT IT......aps st=**** LOL jk guys I will say that my aps exhaust made for the kit did wonders for my boost. Attaching anything smaller then a 3.5 to that 3.5 downpipe is no good. My end tune was like 15 psi to about 13 and that was on the stock spring.

 

c'mon...r u serious?

i already upgraded my exhaust to the APS 2.5" TD exhaust to get rid of the restrictive reducer.

now u say it might need a 3.5"? I'm gonna have Rob try to solve this first without upgrading.

first is first, verify there are no exhaust leaks, and if there are, fix them.

second is to check on the plumbing.

we'll then verify things on a dyno.

i will update this thread once i get some good info.