Hey guys this is the graph for the turbo I have on the 3.0 supra, I bought this from a friend few years ago and had it put on the car. I decided to pull the motor last summer and do some forged lower, head work and cams. Can someone explain what this graph means and how much power can it support on a 3.0 motor … thanks

turbo spec:

SUPER 70 60.5mm • A/R RATIO .70 • TURBINE HOUSING A/R .84 • COMPRESSOR HOUSING .70 • T3/T4 FLANGE

 

You can get about 10 hp for each LBS/MIN of air flow. So the x-axis is a 'hp/10' scale. That turbo max out at about 900 hp.

Pressure ratio is boost/atmospheric pressure.
1 is 0 psi boost.
2 is 15 psi boost.
3 is 30 psi boost.
4 is 45 psi boost.

The turbo is most efficient in the inner most circle. ( 500 hp @ 20 psi boost )

You need to stay inside the graph.
The turbo can deliver air for 900 hp @ pressure ratio 3 (30 psi boost).
At pressure ratio 2 (15 psi boost) it maxes out at 700 hp.

 

so is this a good size turbo, we plan on running 20-25 lbs . can i reach my goal of making 700hp with 25 lbs of boost or should i stick with 20 because it where its most efficient @.

 

If you look at the diagram you will see that the most efficient area is a slope. At higher pressure it is more efficient at higher air flow.

Look at this diagram, wastegate set at 25 psi:



You will reach 25 psi at 450 hp with the turbo spooling about 80.000 rpm. As engine rpm increases and the engine consumes more air the turbo will spool up more along the horisontal line. At about 550 hp the turbo is most efficient. At about 900 hp you max out the turbo when it is spooling 106.000 rpm.

This seems loke a good tubo for you on the compressor side shown in the diagram.

The turbine (exhaust) side is also very important.

A small turbine will spool the turbo sooner but it will also give you higher exhaust pressure at higher rpm. You need a cam with more lobe separation to keep the engine breathing with high exhaust pressure.

With a big turbine the turbo will spool later, but you will make more power at the same boost level because of the lower exhaust pressure. You can alse get away with a cam with less lobe separation.

 

uh oh, the graph you posted is for a turbonetics T70 turbocharger which has a true 70mm compressor wheel minor diameter. the turbo you posted up in text "super T70" is MUCH MUCH smaller. it has a 60.5mm compressor wheel minor diameter. the super 70 is an ebay type turbo, a noname type, it may be a good turbocharger but if your going through the trouble of forging the bottom end of a 2jzgte and putting cams in and having portwork done to the head you need to sell that turbo off and step into a better unit.

If I were in your shoes I would say there are a few options out there, a great turbo for that motor with your mods would be a Garret GT4294 which is a true 70mm compressor wheel and will flow even a little bit more then the graph you posted since it is newer technology and you can probably get around 750-850rwhp out it with a good tune safely on some leaded fuel.

the next step up from there would be the GT4202 which is the same turbine wheel but a larger compressor wheel. 74mm on the minor side and this turbo I have seen on 2jz's put down in the mid 900rwhp range.

if this is more then what you are looking for then you could look at the T66 which is a great turbo, awesome spool on the supras and a good solid mid range and top end. probably somewhere in the 650-750rwhp dialed in.

I hope this helps!

Chris

 

i know , lol for an ebay turbo its not bad. the car made 400 to the wheels with stock motor and bolt ons. the turbo is not bad at all we had 0 problems with it . my friend bought it for $300 of ebay and i got it from him for $100 . the motor is a 7mgte its not the 2J motor . im over on the supra forums and they are all bunch of followers. most guys make 0ver 600 rwhp and run 13ss they think bigger is better.

im trying to prove to them guys that i can make less power and run faster than 80% of them . they all said that this turbo will not last and already proved them wrong, they said that the stock 440 cc injectors will not handle 400 rwhp and i proved them wrong.

i had my head guy do some porting on the head and got the head to out flow all the flow numbers they posted and with the stock valves. my goal is to get the car to run in the low 10s which i know it would do with no problem ...

the car is super fun, and its a daily driver, its much more fun to drive than my vette, and is for sure a sleeper.