I know a lot of you have installed forged components and I assume you're running without problems. Did your shop happen to mention anything about piston clearances or ANY other tolerance issues? (No, I'm not talking about that early batch of Arias pistons.) Is it normal to have to machine brand new pistons?

I'm in the middle of my forged install and I cautioned my machine shop to clearance EVERYTHING after reading about some of the early problems. They're telling me that they'll need to machine my pistons, or send them back to the manufacturer to do it. They contacted them directly, and concluded that they don't even have a VQ35DE block for R&D!

Is this normal and do most machine shops just take it in stride? Am I being finicky?

Thanks for your input.

Bruce

 

Well if you are using a stock more forged piston, most of the time you will have to bore out the block a tiny bit to allow for heat expansion of the aluminum. I have yet to look much into the VQ blocks, but most of the Nissan blocks we have worked on we had to do that.

 

What needs to be machined? If they are just notching the pistons for valve clearance then that is fairly common.

 

Which brand of forged pistons are you using?? Many of the manufacturers seem to just buy a new piston from a dealer and use it as a model without even checking their products in an actual block. When your shop said they had to machine the pistons is most likely for oil squirter clearance...I can't see anything else needing to be machined....except if they are being balanced.

 

Thanks for the responses.

drumma022- I'm using pistons that are +.20 so I expected to bore the cyclinders using a torque plate.

teh215- they're talking about further "clearancing" pistons that are already notched for the oil squirters.

g356gear- I bought CP pistons after the Arias oil squirter clearance issue. My reasoning was that they just didn't do their homework, so went with CP.

The shop told me that the piston to oil squirter clearance isn't the same from one bank to the other and that the manufacturer should really be labeling the pistons according to which cylinder they're matched to?

Then, there's the complete lack of availability of main bearings for this application (thanks again to Steve @ Courtesy Nissan for importing mine so quickly), and let's talk about the wastegate limitations of the APS kit for those of us running low-compression forged pistons. If the wastegate actuators are only good for 11psi, I'll probably only be able to generate about 400whp. That my friends, is a rip. Anybody have a connection at Garrett? They supposedly manufacture wastegate actuators that can handle more boost, but they're under license to HKS or some b*llsh@tt?

 

I had a friend that installed CP pistons in his EVO8 and had clearance issues on the sides of the piston and were rubbing on the cylinder wall when the engine got hot, he had to machine the sides of the pistons down

 

[QUOTE=brucekgt]

and let's talk about the wastegate limitations of the APS kit for those of us running low-compression forged pistons. If the wastegate actuators are only good for 11psi, I'll probably only be able to generate about 400whp. QUOTE]

How low compression are you running?? With 9.0:1 for example on 11-12lbs of boost you should be putting down close to 500 hp.

 

g356gear-
I'm using 8.6:1 CP pistons. A similiar setup turned 409whp/389tq at AAM with a reflash and tune. (That's how I know the APS wastegates can only handle 11psi.) We're looking for stronger actuators. It seems like a waste to make all these upgrades for that type of return. Do I sound frustrated?

Bruce

 

That sounds extremely low for that amount of boost. We have seen cars on the boards get that hp and more with stock compression and 9 lbs.(Barthelb has 440hp at 8.5lbs on stockblock with APS TT) Each 1.0 drop in compression should only drop power about 3%....so 1.7= approx 5% power decrease. Guys like Phunk (573 hp at 14.5 lbs) and Tuan at GRD are getting a ton more power as well with similar boost levels. Something is off with that tune.

 

g356gear-
I expect to lose horsepower when I reduce the compression ratio to 8.6:1. To compensate for the loss, I'll need to increase my boost. Tuan is still running stock internals, right? I can't remember what Phunk has done to his. I hope you're right.

Thanks,

Bruce

 

Bruce,

I feel your pain and frustration, I am in the same boat. My motor will be ready at weeks end and I have NO leads on wastegates. My car has been sitting since December... maybe it'll be ready by NEXT summer now....

 

Phunk is fully built.

 

Peter told us to contact Forge in Florida (I believe it's Forge Motorsports, not sure) about the wastgate actuators.

 

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

 

I received a great link to an earlier post. I'll be pursuing it first thing in the morning.

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

Thanks for the help guys!

 

You still think the T4 one would work?

 

That's why I wanted to contact them to confirm.

 

Bump. Anybody come up with a solution yet?

 

buy a greddy TT?

 

Ouch! I looked at the Greddy kit, but I had concerns about liability if I removed the front bumper support and relocated the airbag sensor:-)