Turbo Hp Rating Question

[iz32]

im just looking around at different RB20 turbo combos and have a question re power ratings manufacturers quote on turbos..

for example the HKS GT2510 unit says its good for 300hp

now is that an approximate figure for an "efficient power" rating or a "maximum flow" power rating?

[rb26s13]

Its a power rating at the FLYwheel.. some say they underrate a bit.. some say they are fairly spot on..

from memory a 2510 will get you around 205rwkw on a rb20 depending on your setup and tuner

[discopotato03]

The GT2510 is outdated thinking , better things around .

[iz32]

The GT2510 is outdated thinking , better things around .

i already have one, just using it for a reference point to get an answer

[Guilt-Toy]

you got what you got.. say 205 rwkw is the most you can get.. at least that turbo has a good resell value and you can upgrade without any issues.....

that rating is HP at the engine.. a skyline can lose 25% 0 %40 at the rear wheels dependant on configuration.

You would have a really zippy car with that setup... make sure you got the supporting mods before you upgrade

[r33_racer]

I believe the drivetrain loss is static and normally about 85hp. Drivetrain loss doesnt increase as engine power increases.

[Warpspeed]

It has absolutely nothing to do with engine power.

The standard method of sizing turbos used by Garrett and most other other turbo companies these days, only refers to the compressor airflow. If you look at a compressor map, and draw a horizontal line at a pressure ratio of 2.0 (14.7 psi boost).

You then move along that line into the choke region at the right, until the adiabatic efficiency drops to 60%. The airflow figure that the turbo can produce one bar of boost at 60% is the airflow rating for that sized compressor.

You then assume 1.5 CFM per horsepower to turn that airflow into horsepower.

You then know that a 300 Hp turbo can supply 450 CFM of air at 14.7psi boost with an adiabatic efficiency of 60%.

It may produce 300 Hp on a real engine, or it may even produce a lot more than that at much higher boost pressures. Or a lot less power if the turbo is not well matched to the engine.

It is just a very convenient way of comparing one sized compressor to another size of compressor by measuring both under exactly the same operating conditions.

[R33S2]

You then know that a 300 Hp turbo can supply 450 CFM of air at 14.7psi boost with an adiabatic efficiency of 60%.

So a 450hp turbo can supply 675cfm @ 1bar? Or is it expontential?

[Warpspeed]

A 450 Hp turbo will indeed supply 675 CFM at 1 bar boost. The compressor flow map will confirm that if you look.

[iz32]

It has absolutely nothing to do with engine power.

The standard method of sizing turbos used by Garrett and most other other turbo companies these days, only refers to the compressor airflow. If you look at a compressor map, and draw a horizontal line at a pressure ratio of 2.0 (14.7 psi boost).

You then move along that line into the choke region at the right, until the adiabatic efficiency drops to 60%. The airflow figure that the turbo can produce one bar of boost at 60% is the airflow rating for that sized compressor.

You then assume 1.5 CFM per horsepower to turn that airflow into horsepower.

You then know that a 300 Hp turbo can supply 450 CFM of air at 14.7psi boost with an adiabatic efficiency of 60%.

It may produce 300 Hp on a real engine, or it may even produce a lot more than that at much higher boost pressures. Or a lot less power if the turbo is not well matched to the engine.

It is just a very convenient way of comparing one sized compressor to another size of compressor by measuring both under exactly the same operating conditions.

cheers to the other responses, but this was the kind of generalised answer i was after, thanks warpspeed.

sorry if i worded the thread incorrectly peeps