I'm well into my forged engine project and wondering what kind of power I should expect from the APS TT kit after switching to low-compression pistons? I've seen some impressive numbers from Phunk and Tuan and others, but aren't they running stock internals? What can I expect from my setup with 8.6:1 pistons?
(Hint: I've already been told the wastgates can only handle 11 psi before they're overwhelmed.)

I'm not having any luck finding wastegate actuators that can take more pressure, so how much power will I be able to make with the stock ones?
One answer so far is 409whp/389tq which will be a lot of fun, but not nearly what I was after. Anyone?

Thanks,

Bruce

 

hey bruce, hows it going? i can't answer your question, but letting you know i have decided twin turbo also!! hahaha. should be here tomorrow! motor is heading for machine shop on wed. so our cars might be done about the same time. pir opens up this weekend for street legal drags, so let me know when you get yours done and we can meet out there for a good 'ol grudge match, lol.

 

While you have the motor out being built put in stiffer wastegate springs. There's a thread below with suggestions. Sounds like it would be a PITA to do later with everything assembled.

link:
https://my350z.com/forum/forced-induction/123605-why-wont-aps-tt-go-past-9-10-lbs-boost.html

 

I am not 100% positive but I think I have seen in someone's sig 560whp on the APS TT. I don't know if this was on the 12psi limit a lot of guys are hitting. Although, I have not seen any post that they were able to fix that problem. There are a couple of guys tyring new actuator right now. For sure I have seen 505whp on 10.5psi on a stock motor.

 

Thanks guys. That was an awesome link. I've been so wrapped up in my frustration that I completely missed that thread. Just another great reason to be on the forum.

Bruce

 

I got worried when Julian said he was only making 409hp/389tq and overpowering his wastegates at 11psi. My shop has been trying to talk to Garrett for three weeks. They even have an employee whose brother works(or worked) there and still they're no help. Can't wait to talk to Forge.

 

I have sent an e-mail to the boys at Forge in Florida telling them about the situation. Hopefully I will hear back tommorrow.

 

Bruce the actuators were not being overpowered as the actuators are designed for 6.5 to 7 PSI applications and the electronic boost solenoid in the APS twin turbo controls the rest, (Julian had the boost control solenoid disconnected, hence the lower boost pressure) that is controls the boost pressure up to 12 PSI with a low back pressure exhaust system and test pipes.


I have a few 12 PSI actuators in stock if this helps though please remember that 12 PSI boost will be the min boost you will be able to run and that's the limit of the stock APS twin turbo fuel supply system right now - you will also need to get the computer remapped to suit your new engine combination, comp ratio, boost level, etc, etc.

Pm me if you need any help and I will run through some options with you.

Thanks

Peter

 

Peter-
I love reading your posts Peter. To say the wastegate actuators are not being overpowered when the boost exceeds their design limit is like being "sorta pregnant". Can the stock actuators hold more than 11-12psi? NO.

If I locate 10psi actuators, will the unichip have the ability to adjust within a range of 10-20psi? Or, is it going to be much more limited than that? So far, Garrett has been totally unresponsive. I haven't seen any solutions posted yet, but I'll continue reading.

Thanks,

Bruce

 

Is it recommended to reflash the ECU to work in conjunction with the Unichip?

What size are the injectors that come with the APS kit?

 

I think peter is saying that the new boost floor will be 12psi, and then you should be able to run double that with a boost controller. Of course, as Peter has posted before, there is only a minimal airflow increase between 15psi and 20psi on the APS turbos, so most people will probably stop at about 15-16psi....assuming a built motor...fuel upgrades...etc...etc..

 

Thanks Sharif. I've got a line on actuators that will supposedly give me a 10psi base and be adjustable up to 20+. I don't want to be in the highest hp crowd, but I sure didn't plan to spend what I've already spent and be limited to 400whp. I've been without my car since April 11th. We had 200% of our average Oregon rainfall for May.
I'm commuting on my motorcycle. I feel like a factory rider for "Team Goretex".
I may have to plan a roadtrip in the roadster just to dry out.

Bruce

 

Over 500whp is no problem with the correct goodies....

Compression ratio is debateable.