Engine power at 0.5 bar

[Billman]

Just out of curiosity what would the engine output be if we run the car at 0.5 bar (spring pressure)?

[EspenW]

Which engine?

[Billman]

2.2 or 2.5 liter I5.... a rough estimate..... I went yesterday to the dyno but my old N75 (I was lazy and didn't changed to the MAC) decided that it would not like to work and I didn't managed to make a run above spring pressure. It spooled to 0.6 and tapered to 0.45

The power output was 200 hp and 290 NM.

[prj]

It depends on the volumetric efficiency and displacement of the engine as well as the amount of timing you can run and the compression ratio.

[Rocco]

and depends on wich turbo true? its not the same 0.5Bar of the stock turbo over 0.5bar on a GT30R...

[Billman]

of course that's why I asked for rough numbers. I wanted to have something to play with my thoughts.....

my engine is a low compression stroked engine with a big turbo.

[prj]

Turbo does not matter, IAT does. Bigger turbo will be more efficient and give lower IAT.
Anyway, it is almost impossible to give any accurate number.

[Billman]

i see...the IAT in there where about 45 degrees

anyone has a stock 3B dyno to see? what boost did it run from factory?

[Jamo]

3B runs 0.8 bar stock and will give around 220 bhp, not sure of torque, there are plots on the forum

[Billman]

nice thanks....I will sort these out and hopefully go again in a couple of weeks for a proper run...

I also had some Sec trigger error over 6000RPM.....maybe because I don't run the hall inverter yet....

[mcandmar]

Surprising, i would have thought a larger turbo would flow more air than a stock K24 at the same pressure? Or have i got the wrong end of the stick?

[Billman]

I think it is a bit more than what the K24 would produce at 0.45bar but minor difference.

I believe it was something to expect if you consider 8,3:1 CR compared to the 9,1:1 of the 3B the conservative timing and maybe with the turbo efficiency. Mostly big turbo are more efficient above 1 bar....

[prj]

I will say again, it does not depend on the turbo, it depends on the IAT!
With 45C IAT you will of course not reach any good power.

You will lose power because of the CR, but gain some power due to displacement.
Over all your figure sounds right on target.

[Billman]

thanks for the input. I just soldered a Bosch 2 pin connector for the replacement MAC valve.

[rst]

I mapped the car a little bit in the weekend and at the moment i'm running 1bar boost. New engine has driven for now about 1000km.
With 1200cc and RON 98, the injector duty is about 36%, so it's about ~250kW from the flywheel.
I think useing the duty cyle in these calculations will give a more precise outcome in power figures than just saying what boost you are holding. The AFR of my car is at the moment little bit below 12 at WOT.
I used this link:

http://www.rceng.com/technical.aspx