Turbo HP Ratings...???

[GiJOr33]

Just wondering about turbo hp ratings and what they actually mean.

For instance, a HKS GT3040 is rated at 500hp. Where is that measured from? And aren't there cars that produce over 500hp with this turbo?

Thanks

Andrew

[Steve]

I believe HKS turbos flow 10% higher than quoted at 1 bar. This is not on a car though - this is in a test environment.

The HKS turbos operate at there optimum at around 1.5 bar.

Merli has stated he is making 280rwkw on a 3040, but I am not sure how much boost he is using to do it.

There is a SR20 getting around with 300rwkw on a 3037S.

Munros 3L makes 900 odd hp (I think) with twin 2835Rs.

[Leewah]

We've had a SR20 make 305rwkw with a 3037s kit on a dyno dynamics dyno which later ran a flat 12 @100 mph, lifting off at half track.

The HKS turbos are speced much lower than their actual flow capacity. This is done for warranty reasons but it is widely accepted that the turbos will flow much more than speced

[Warpspeed]

Garrett spec their turbos at 1 Bar pressure, (pressure ratio = 2) at the 60% efficiency line on the flowmap (which they will not give you).

Now flowmaps all tilt to the right to some extent, but the efficiency curves can vary quite a fair bit in shape from wheel trim to wheel trim. Also the compressor housing a/r will effect the flowmap shape as well.

Small a/r makes the flowmap tall and skinny, large compressor a/r makes the flow map shorter and fatter.

So if Turbo X flows 300BHP at 1 bar boost, it MIGHT flow 340BHP at 2 bar boost, or it might not.

There is the opinion around that a Garret turbo is total crap, and an HKS turbo fitted with identical Garret wheels is somehow absolute majic. Yeah maybe.

Garret supply HKS with all the rotating assemblies, HKS just make the housings with the HKS name on the outside, and charge twice as much.

[GiJOr33]

i thought HKS had different trims etc as well.

I don't really know what a flowmap means... or how to read them. Is there a site on the net that you'd recommend me reading? I'm interested to learn what it all means, likewise, i don't know much about A/R's end Trims either... All i know is bigger turbo gives more power topend and less bottom end, small turbo spools quicker and gives more low -mid range power, but runs out of puff at the top end. That's about as far as my turbo knowledge takes me

[Warpspeed]

Andrew, get onto Google, and find Ray Hall Turbocharging.

He has a good web site, with a lot of information, as well as some flow maps you can look at.

Also there is a very good book Maximum Boost by Corky Bell, available for around $100, but well worth it.

[GiJOr33]

yeah... i've been seeing that book mentioned a bit the last few years, i think it's time to make the purchase

Cool, i remember having a chat to Ray Hall about something on my old skyline... very helpful!!!