GTM TT 370Z Owners... Help? - Preparing to start my GTM TT Build.
 

Ok, so i am about to purchase GTM's TT kit for my Z.

Thinking of going with Stage 1 with 10.5 psi spring and Tial BOV's.

I'm looking for around 550rwhp. Will stage 1 get this done at 10.5psi?

Will it benefit me any if i bump the turbo to stage 2 and keep the 10.5 psi spring? Or if i up the turbo should i go with the 11.6 psi spring?

I'm just trying to get the most out of the stock motor while staying somewhat conservative. If stage 1 will do this... then so be it. But if i can upgrade the turbo, up the boost a couple of psi and squeeze out close to 600 rwhp safely (within reason)... then hell why not?

Just want to do it right the first time and not get used to the car then have to upgrade later.

Also, is there anything else that is absolutely necessary or recommended to purchase and have installed with this turbo kit?

Clutch, flywheel, fuel system upgrades? I have an oil cooler, but i think it's the smallest one stillen makes. I'm assuming i should upgrade to a larger one?

Again, just want to make sure i do things right the first time. Most likely going to take the car to Dallas and let imported performance tear it apart while i drive around a rental until they are done.

Any and all advice would be appreciated. Sorry if these are newb questions... but i just want to hear from some guys that have real world experience.

get the stage 2. and dont get a spring that large. get a smaller spring and use a boost controller to take it up from there. 10.5 or 11.6psi will make too much for the minimum power IMHO, especially if you ever let anyone else drive your car.

personally i run a 6psi spring so with boost controller off i make 450rwhp and thats a nice conservative DD power level, and pretty dang low risk in terms of engine failure, even the older DE motors could hold 450 all day. its effortless to drive and quick enough for most circumstances. also, i am much more inclined to let a friend drive the car like that because it really only blows the tires off in 1st (305 RE11's with 1.4 degree neg camber). at 8psi the car rips thru the tires in 2nd, and thats too much wheel spin for a less experienced driver. the smaller your turbos the faster they will come on and the more wheel spin you will get... thats why i say go stage 2... because the extra torque from the stage 1 is going to just be wasted to tire spin anyway, and once your in the higher gears of a race you would never be at those lower RPMs anyway. im using the greddy 20g kit which are pretty large turbos, i would expect the GTM stage 1 and 2 kits to both make more low end torque and be more responsive, which is fun in its own right, but for the type of HP these cars make with boost, i personally believe that turbos can come on TOO early making the car a lot more of a handful then it needs to be, without making it any faster in a "race" situation. so i say the larger the turbos you get the better (within reason), and remember bigger turbos make more power at the same boost pressure, so if anything you would want smaller springs with a higher stage, rather than larger springs.

get a clutch and flywheel. your turbo kit will come with a fuel system. upgrade your oil cooler core if your oil temps are constantly over 220 with your driving style after the turbos. to even have one at all is better than nothing so i wouldnt exactly worry about it yet unless its a problem.

all just my own opinions of course.

I am running stage I at 8psi. I haven't gotten on a dyno yet so I don't know how much power I am putting down. I have the stock clutch and so far it is holding up ok. I was up near 10psi at first and I would slip the clutch at high rpm.

As far as an oil cooler goes, I am running a 34 row cooler and never see temps above 220. Even on 90+ degree days and spirtited driving. I think the stillen is a 25 row. I see you are in Texas. You might want to get the 34 row.

And put some money aside for rear tires. :D

Same turbos on both kits. If you go stage 1 for quicker spooling turbos (a little) but decide in the future that want more power you can upgrade to the .86 housing that comes with the stage 2 (aprox $200-$250 each). GTM has pushed over 580rwhp on stage 1 turbos (.64 housing)

I would (and in fact will) go stage 1 since I have no plans of pushing more than 500rwhp on a stock block and if I ever decide to build the engine I will then uprgrade housings, or just swap out for bigger turbos.

You can use the stock clutch until it gives out. A 34R oil cooler would be the best option in TX but you can keep the 25R and keep and eye on temps, then decide if you need to upgrade. Fuel system is included with the kit, but you will need to get one step colder spark plugs. Also I agree on going with the 6psi (5.88psi) spring and getting a boost controller. HKS EVC-S can be had for about $350.

Boost and AFR gauges are good ideas so that you can monitor and catch potential problems before they occur.

Just my 2cents :D

Thanks for all the replies!

I guess i was confused on the fuel system, because it doesn't show any injectors or anything in the photos on GTM's website, but they do show fuel system upgrades at the bottom of the page for additional $$$.

Is a flywheel upgrade necessary, or not so much? Also, should i go with a certain "stage" clutch to handle the power? Any recommendations on brand of clutch?

Some of the pictures on GTM's website are a little deceiving also. On some of the pictures it shows that the kit comes with downpipes that replace the cats where a dump tube hooks to. Is this the case on the GTM TT kits? If so, any issues with passing smog?

What about exhaust? Right now i have JIC Y pipe and TopSpeed Pro1. It's a single exhaust... should i go to a true dual? I know GTM has a 3" catback, but for $1,900 i was thinking i could just go with an HKS or something similar.

Thanks guys!!

A flywheel is not really necessary. I used to have a Southbend clutch on my Z32 and loved it so I would probably go with their stage 4 clutch and upgraded csc. It comes down to less than $900 for both.

Downpipes with external wastegates are optional, that's what you are seeing on the pics, you can vent them to atmosphere (illegal) or you can recirc back to exhaust. They are $1k+. You can get 3" testpipes instead for less than $400.

If it's within budget I would upgrade exhaust, it does not have to be a 3" though. HKS Turbo Ti is 2.75" and even a nice flowing 2.5" will do

Stage II support from this department.

The power is almost immediate and linear. You will have some authority.

A pleasure.

Coop

a larger exhaust housing increases top end flow but decreases response. that is what i was talking about in terms of "larger or smaller"

Yeah I gotcha. I was trying to say that a stage 1 is able to deliver the power he wants with a bit better response time and that the only difference is the exh housings which can be replaced if needed. :)

Wouldn't the Stage 2 benefit better with aftermarket exhaust (say 3" tubing) over the Stage 1? I was going to get the Stage 1, but got talked into getting Stage 2 :)

Go with the stage 2!!! With a stage 2 you have more room to grow... I am running 12 psi on the stock block and pushing just over 600rwhp daily! It's worth it for a few hundred more ;) :tup:

^^You just about talked me into it.



haha jk. I was just about to pull the trigger as well.

Correction: HKS Hi-Power is 60mm piping or 2.36".

The Greddy Ti-C is 2.75 though..........hint hint

One of the many reasons might switch to FI 18" carbon fiber catback or GTM 3".