Effect of altitude on power

[Seven in SA]

I was wondering how much effect altitude has on the output of the car. I have a Toyota engined Birkin which is pushing 160BHP at the Flywheel and about 114 at the wheels (do these calcs seem right?). These figures have been quoted up here in Johannesburg (not sure how high we are), how much improvement could I expect at sea level.

 

Thank you

 

Nic

[Peter Carmichael]

Reputable rolling road operators should normalise the output to DIN standards. Emerald have a thermometer and barometer above the RR console and enter values into the computer after each power run.

 

Don't know the elevation in Brixton, but I do know my power figures are corrected. You could ask and see whether your rolling road operator has the same sort of adjustment.

[Tony Martyr]

Johannesburg I think is on the highveld plateau at about 1500 metres (I had to commission a big pump system around there once and had to make significant adjustments to head calculations). So your engine will have a lower mass fuel flow than down on the coast, particularly in your summer heat. All I remember about cars in that city was the awfull static shocks I got - you learn to shut doors with your bum.

I suggest you phone the engineering department of SAA at the Airport they might tell you their power reduction factor which they use in testing rebuilt engines - they have more power than you but it is the same air.

I think your internal power losses are about right if you have a LSD.

[Miraz]

I'll be in Johannesburg on Sunday....but driving a shed unfortunately...

 

Miraz

[Seven in SA]

Cheers guys,

 

I have just spoken to the chap who installed the engine (I am yet to play with it) and he reckons they have not adjusted it for the altitude (also says the diff is about 10-15%). The other good news is that at this stage they only took it to 6000 rpm's and the BHP curve was not showing any signs of 'flatting out'. I know that at sea level the Toyota 4AGE 20v engines produce 154BHP@7400 (flywheel) so I am already above that with a couple of thousand revs to play with. We were looking for about 180BHP top whack, so if we can get that here it should be a bit more on the coast or in the UK.

 

Cheers

 

Nic