i have TT. For that price for a single I would have definitly went that route.

Dynojet rescheaduled for tomorrow due to the cold front hitting with rain and hi hummidity. We figured numbers will be more accurate with decent weather. Ill keep yall posted.

Sent from my SAMSUNG-SGH-I897 using Tapatalk

Sam and GTM are great they put out awesome products and helped us with this build as well. Yes smaller turbos spool faster. Like i said from the get go, I wanted sonething diferent. This build is exactly what i wanted and thats all that matters. The sound this kit makes is crazy. All you hear is turbo. Makes me smile!

Sent from my SAMSUNG-SGH-I897 using Tapatalk

Actually, that's one thing that I missed when I test drove the GTM turbo setup. I really like a lot of turbo whine.

I know what u mean. In my greddy/CJM 350 all i could hear was wastegate. I just heard Haltech mite be releasing a computer at SEMA to controll cams, etc.... Hopefully GTM will release their GTR manifold too!

Sent from my SAMSUNG-SGH-I897 using Tapatalk

full boost at 3000 rpm on twin t25 flanged turbos with log manifolds isnt hard to do. we have a g35 here that is fully built that has twin 2860rs on a jwt kit that makes full boost at 3000 but maxed out at 550 whp. if we would have done t4 divided setup, then the boost wouldve came on a bit earlier. We will have video and dyno chart up tomorrow of the dynojet tomorrow. rained a bit here in houston today and the car needs an alignment

what's the max psi you would push through a gt2860rs before it stops being efficient?

i would guess around 11-13psi?

either way, it's more than the stock motor could handle.

We have gone over 20 psi and made over 600 RWHP and still had room to go,on a VQ35DE engine. A VHR engine can do better . I'll dig up a compressor map and post up.

Sam

uuuh no.. 12psi with the right octane is good for over 500whp which seems to be right on the limit for this block in stock form.

I know people pushing/maxing gt2860rs at 24psi. My questions is, at what point do they become inefficient.

Thank you Sam, that's what I was looking for.. I also have a super noob question... How do you measure psi on twin turbo setup? ie: when you say you ran 20psi on a TT is that 10psi per turbo/bank?

SR20 guys with gt2860rs go up to 24 on a single turbo.. does that mean you can double that on a TT?

Measuring boost is measuring boost whether it is a twin or single turbo, I just used the 20 psi example on a car we did in past so i know for fact that The GT28RS can deliver a lot power . Garreet rate them @350 HP each and taht is why you see us rating our STG 2 turbo kit at 700HP witch is under rated .

Sam

misread your question. 500whp is on the limit, but it shortens the life of the block.

i have a friend runs that turbo on his evo, anything beyond 21psi the gain is minimum.

Ok I think I asked the wrong question. I know 20psi is the same on a single or twin turbo setup since its measured at the manifold and not at the turbos.

I guess what I was trying to ask is that if a single gt28rs maxes out at 24psi by you running 2 of the same turbos will you be able to produce double the psi at the manifold if you wanted to?

Ok, first of all, here is a compressor map for the GT2860RS Turbo:


The Y-axis is Pressure Ratio and the X-Axis is Air Flow. The islands are the efficiency. As you can see, the efficiency is not simply a function of pressure ratio.

Pressure Ratio is how much the turbo is compressing the air relative to the inlet air pressure. So, at sea level where the ambient air pressure is roughly 14.7psi, a 1:1 pressure ratio will yield atmospheric pressure (0psi of boost) and a 2:1 pressure ratio is 14.7 psi of boost. To calculate boost pressure, multiply atmospheric pressure by the Pressure Ratio then subtract atmospheric pressure.

Remember that boost is simply a measure of restriction. The X-axis on the compressor map is the one that matters when looking at horsepower. Lbs/min of air directly correlates to lbs/min of fuel you can add. Fuel plus air = power.

Now, back to the efficiency question. Since the islands represent efficiency, this turbo is most efficient in the middle island. That said, if you think about setting a boost pressure (horizontal lines) and rev the engine through the range of the engine, the efficiency is going to go from low, to high and back down again at the same boost pressure. Now, if you want to hit the peak efficiency through the rev range of the engine, you'll need to run between 7.5psi of boost up to 19psi of boost. The sweet spot for this turbo is right around 15psi of boost. That will give you peak flow for the turbo while keeping it efficient.

In the case of a Twin Turbo setup, the flow rates are added together and boost pressure for both turbos are the same. So, to get the most out of a twin setup and run it as efficiently as possible, you can flow up to 70lbs/min of air at 15psi of boost. The rough rule of thumb is that for every lb/min of air you flow, you make 10hp. So, that's roughly 700hp potential for a pair of GT2860RS Turbos.

Pressure ratio is not additive but air flow is.