GTM Performance Engineering: GTM TD05 16G Test Results 91 Octane 7AT

FPenvy · 07-18-2012, 01:26 PM

Quote:

Originally Posted by Scribe

My comment below isn't directed at you specifically, but is more of a generalization.

Running 93 won't be an issue as long as you are willing to keep the boost down to safe levels. The advantage you will see with 93 octane is a safer margin against detonation which is well worth losing a few inches in the pissing contest of dyno numbers. Just because you can turn the boost way up doesn't mean it makes sense. That's why I dislike the larger turbo kits for an unmodified VQ37. I don't need a huge turbo since I can't push more than 550whp anyway. I'll take the quicker spool all day over bragging rights about how much power two giant turbos could make.

Now if you are looking to future-proof your build, buying the larger kit may make sense. I would still argue there's tons of usable power left on the table with these turbos if you threw in beefier rods and lowered the compression.

lots of good info

i agree with what youre saying. the main problem i'm running into right now is not only comin up with the money for the TT kit but also the transmission upgrades since i would really like to be able to have a fully functioning car rather than losing the higher gears just for high HP numbers lol

this new kit is amazing though. lots of power in a small package.

Scribe · 07-18-2012, 01:35 PM

Quote:

Originally Posted by FPenvy

lots of good info

i agree with what youre saying. the main problem i'm running into right now is not only comin up with the money for the TT kit but also the transmission upgrades since i would really like to be able to have a fully functioning car rather than losing the higher gears just for high HP numbers lol

this new kit is amazing though. lots of power in a small package.

Don't forget to factor in a very nice boost controller. Speaking of which, I don't remember seeing anything about whether this car had one or not. I'd be interested to see both the boost and afr overlays for the dyno pulls.

I know that turbos work off of the pressure differential between the exhaust manifold and exhaust and that the best exhaust for a turbo is no exhaust. Still I would like to see what high flow cats and a straight-through style exhaust can achieve.

I also am curious if there is a divider within the down-pipe to keep some separate of the exhaust from the internal wastegate.

FPenvy · 07-18-2012, 01:42 PM

Quote:

Originally Posted by Scribe

Don't forget to factor in a very nice boost controller. Speaking of which, I don't remember seeing anything about whether this car had one or not. I'd be interested to see both the boost and afr overlays for the dyno pulls.

I know that turbos work off of the pressure differential between the exhaust manifold and exhaust and that the best exhaust for a turbo is no exhaust. Still I would like to see what high flow cats and a straight-through style exhaust can achieve.

I also am curious if there is a divider within the down-pipe to keep some separate of the exhaust from the internal wastegate.

all questions someone from GTM will have to answer but i'm interesting in for all those answers too.

personally i wouldnt mind running no exhaust since the turbos are kinda mufflers already. then again i just like very loud and mean sounding exhaust on cars hence my non-res set-up which still isnt as loud as i'd like.

Wattles · 07-20-2012, 08:44 AM

Quote:

Originally Posted by Scribe

Don't forget to factor in a very nice boost controller. Speaking of which, I don't remember seeing anything about whether this car had one or not. I'd be interested to see both the boost and afr overlays for the dyno pulls.

it's a Blitz SBC with remote control on the steering wheel.
Fun stuff

Scribe · 07-20-2012, 08:58 AM

Quote:

Originally Posted by Wattles

it's a Blitz SBC with remote control on the steering wheel.
Fun stuff

Thanks for the information. Any issues with controlling the boost with the various exhaust configurations you guys tried? Did you go back to using the stock exhaust?

Mike@GTM · 07-20-2012, 01:47 PM

Quote:

Originally Posted by Scribe

I'm super excited to see such a well matched kit for the stock VQ37 and happy that GTM didn't nerf the results in order to prevent cannibalization of their larger turbo kit. I was also concerned by the idea of cutting costs, but GTM have shown they don't cut corners and it is encouraging to see the results.

Some smaller turbo or supercharger kits exclude blowoff valves. Running 10 psi I'm happy to see they are present. But that leads me to ask about running 10 psi on the stock rods, especially on 91 which detonates almost as soon as you put it in your gas tank.

Some people seem to be finding the upper limit of these rods to be around 550whp and I would have concerns about longevity. Are there any concerns from you guys at GTM? I live the in the land of 93, and probably wouldn't want to run more than 9 psi, but could see an issue where people tune their cars to run 11-12 psi on 93 octane and then throw a rod through the side of their block.

It's not a question of boost pressure, it's a question of cylinder pressure. Average cylinder pressure is measured by torque at the wheels. The other factor is load. You can make a serious amount of torque and be perfectly fine. When you do a 6th gear pull with tons of torque, however, you are putting way more load on the connecting rods than a 3rd gear pull with the same amount of torque. Therefore, it's really important to be clear about what you are doing with the car when trying to determine what level is "safe" for you.

Quote:

Originally Posted by Scribe

Don't forget to factor in a very nice boost controller. Speaking of which, I don't remember seeing anything about whether this car had one or not. I'd be interested to see both the boost and afr overlays for the dyno pulls.

I know that turbos work off of the pressure differential between the exhaust manifold and exhaust and that the best exhaust for a turbo is no exhaust. Still I would like to see what high flow cats and a straight-through style exhaust can achieve.

I also am curious if there is a divider within the down-pipe to keep some separate of the exhaust from the internal wastegate.

Yes, the car has a boost controller on it.

Generally, we don't recommend high flow cats on forced induction applications because they really just don't last long enough. It's either OEM cats or test pipes. The only time you see us do any kind of testing with HFC's is if the customer already has them and insists on running them.

We use a bell mouth design on our downpipes and O2 sensor housings. In our experience, the bell mouth design works exceptionally well.

Quote:

Originally Posted by XwChriswX

Will you see a performance loss from using the 2 coolers and the crash bar blocking them vs one single cooler without the crashbar as in the previous kit? Although I do really like the idea of retaining the crash bar for safety purposes.

On the twin cooler setup, the charge air flows from the bottom to the top. As a result, the crash bar doesn't really affect the coolingh. The big single cooler on our Garrett kit flows side to side, however, and the crash bar would block airflow to the upper circuit.

Quote:

Originally Posted by Scribe

Thanks for the information. Any issues with controlling the boost with the various exhaust configurations you guys tried? Did you go back to using the stock exhaust?

No issues so far with boost control. Keep in mind, however, that the 16G setup is geared towards people with factory or mildly upgraded exhaust. Think of it as a OE style twin turbo conversion.

That all said, these turbos have a really nice, smooth, rounded transition from the turbine scroll to the wastegate flapper. This allows exhaust gasses to make the tight turn towards the wastegate more easily and ultimately improves boost control.

Wattles · 07-20-2012, 05:09 PM

Quote:

Originally Posted by Scribe

Thanks for the information. Any issues with controlling the boost with the various exhaust configurations you guys tried? Did you go back to using the stock exhaust?

My car had the stock IPL exhaust (which is more flow than a stock g37), but less than we had hoped to have for the TT application so I am having Sam put a Fast Intentions exhaust on as we speak.

I'm hoping to free up the extra horses that are being stifled by the factory IPL exhaust.
We will see how the numbers turn out shortly.

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