My Planned Twin Turbo Setup

[mshawari1]

Just I want to share with you what I am thinking about ….

I have twin turbo Garrett T3 50 Trim from Nissan ..
My goal is 400 FWHP , that is mean 400 * 12 * 055/60 = 44 lb/min.

MAP = {44 * 639.6 * (460 +130) } / { 0.88 * (6200/2) * 244 } = 25 psi.

Pressure Ratio = (25+2) / (14.7-1.7) = 2.07

In my calculation I consider the VE as 0.88, Max RPM = 6200 , T = 130 F and the elevation here is ~ 700 m above sea level ..

And here is the MAP..

What do you think ????​

 

[Lextreme II]

I would go with .48 A/R. .48 will be very fun. Tires burn from the start.

 

[4000GT]

That would be the 300ZX turbos yes? if Im right they have a .63 turbine AR

 

[cjsupra90]

your math is wrong in your pressure ratio calculation.

The calculated MAP is 25psi absolute for one, also that does not get multiplied by 2 either in the pressure calculation. I am assuming that you are multiplying it by 2 cause of running two turbos. The boost is the same whether you have 1 or 100 turbos and does not get divided or multiplied. The airflow rate gets divided equally between all turbos, so the 44lbs/min would be divided between the 2 turbos and therefor each turbo would only have to handle 22lbs/min and both at the calculated absolute pressure of 25 psi or 10.3psi of boost or 1.70 pressure ratio.

To sum it up, each turbo at 10.3psi would be flowing 22lbs/min and having said that, no the 50 trim T3 is not a good choice. The T3 60 trim would be a far better choice.....

 

[cjsupra90]

That would be the 300ZX turbos yes? if Im right they have a .63 turbine AR

Not sure about elsewhere, but here in the states, 300zx's with T3's were 60 trim with the .63 A/R hot side..... Al others were T25 but I dont recall the trims.

 

[XR8tt]

Some are single turbo and latter models had twins...
But this engine shared a single turbo in Japan in more luxo sedans...
I run two of these on a std 5.0 Ford, made 340 rwkw...
They are ball bearing with ceramic turbine wheel..
At high boost or high milage can break off main shaft...

 

[mshawari1]

Those turbo comes from 84 Skyline L20-T and its 0.36 A/R …

Cjsupra .. in my calculation I did not divide the pressure by 2 .. I divide the 44 lb/min as you can see in the plot I assume it is 22.5 lb/min and the ratio as 2.1 .

I have this turbo's one year ago … and I should do some thing ??? The only thing stop me is the host car that I will install the engine in it. I am looking for 96~97 Landrover Discovery with bad engine and manual gear so I can start my project ​

 

[cjsupra90]

Yeah, I know that the flow was divided. I looked at the pressure calculation wrong but still wondering what exactly you are doing in calculating your pressure ratio. I assume that you are subtracting the 1.7 from the 14.7 due to your elevation being ~700m, but where I am lost is why are you adding (the part that I looked at wrong) 2 to the 25 in that same equation?

 

[XR8tt]

The RB engine is too small.. The turbo's I used where from a VG30 T [.63 A.R] or 300 ZX.. Beware of some Skyline turbo's are twin on GTR .. I assume these would be way too small as this motor is 2,600cc...

 

[mshawari1]

CjSupara, This is my fault because I did not declare the calculation …

The 2 PSI which I added because of the manifold and piping loses . And its right I subtract 1.7 PSI due to the elevation.

XR8tt, That Skyline engine is 2000 cc six cylinder in line with single turbo with internal wastage set at 7 PSI I think .

I had before same turbo's but from Toyota M-U 2000 cc 6L with 0.48 A/R .​

One of them damaged after I install it in my 5M-E engine

 

[XR8tt]

Elevation doesn't really count with turbo's as they just spin harder to make the boost set by wastegate.... Unlike belt driven or chemical supercharging...
The turbo from the RB20t would be too small imo even with two of them on 1UZ... Keep in mind manufacteres fitted just big enough turbos..

 

[mshawari1]

What do you guys think about the Landrover Discovery ?? I find that it has All time 4 wheel drive with lock function. Aluminum body with strong heavy chassis. Good seat position !! comparing to other 4X4 its good choice..


Did you agree with me ?
​

 

[marlew]

Just to throw a spanner in the works
what about a pair of stock WRX turbos?
I haven't done any calculations Just wondering what you guys think...

 

[XR8tt]

What do you guys think about the Landrover Discovery ?? I find that it has All time 4 wheel drive with lock function. Aluminum body with strong heavy chassis. Good seat position !! comparing to other 4X4 its good choice..​

Did you agree with me ? ​

The people/ owners I have talked to like them..

 

[mshawari1]

Marlew: The stock WRX turbos dose not fit because its twin turbo for 2000 cc = 1000 cc for each one ......​

 

[XR8tt]

Marlew: The stock WRX turbos dose not fit because its twin turbo for 2000 cc = 1000 cc for each one ......​

WRONG WRX's are not twin turbo!!! [I have two of them]
They are single turbo...

 

[XR8tt]

Twin IHI VF30 / VF34 would hall.....

 

[cjsupra90]

Elevation doesn't really count with turbo's as they just spin harder to make the boost set by wastegate.... Unlike belt driven or chemical supercharging...
The turbo from the RB20t would be too small imo even with two of them on 1UZ... Keep in mind manufacteres fitted just big enough turbos..

Ah, YES elevation does make a differance. A wastegate only make X or XX boost above the current atmospheric pressure that it sees at that time. If you are at sea level (14.7 atmo) and running say 10psi, then the engine is getting an absolute pressure of 24.7psi. now take that car up several thousand feet above see level to where the atmo pressure is only say 13psi, your wastegate is still only going to make 10psi over atmo cause the spring is calibrated to 10psi. So now your engine is only going to see 23psi absolute and therefor make less power so inorder to get back to the original 24.7psi absolute, you have to raise the boost to 11.7psi to compensate for the 1.7 loose in atmospheric....

 

[mshawari1]

Twin IHI VF30 / VF34 would hall.....

I search in the internet and find that the WRX has a single turbo . But I've seen many Subaro engines in wrecker yards with 4 cylinder twin turbo !!

Q: Is there is a way to calculate the turbo boost VS RPM​

 

[XR8tt]

I search in the internet and find that the WRX has a single turbo . But I've seen many Subaro engines in wrecker yards with 4 cylinder twin turbo !! ​

Q: Is there is a way to calculate the turbo boost VS RPM​

The Legasy had twin turbo and water to air intercooler, the latter versions in 90's are 2.2 litres...There was a few h.p versions also.