Haystack

I am running datalogs of airmass and other parameters on my new setup.

I have a gut feeling that there are temperature, barometric pressure and humidity effects that affect the final results. I am not sure if the calculations are the same for turbos as for normally aspirated engines, as the turbos are generating a constant pressure regardless of barometric pressure, but the density of the incoming air (and air used by the IC's) changes directly with temperature and humidity.

Since I am comparing before/after configurations, and the tests I run have spanned several weeks, I'd like a way to standardize the results so that they are valid for comparison.

Since I am not using a dyno, absolute accuracy is not that important. I am more interested in being able to correct my data so that my comparisons are relevant.

Could someone point me to a source of info regarding correction factors (and formulas or data tables) used by folks here and in industry when doing comparisons with turbo setups?

Greg Woo

Haystack,

Just read your message. I have done some research on this as well, and as far as I know, the SAE J1349 conversion for barometric pressure, altitude, and air intake temperature does not apply to forced induction vehicles. Your comments above are exactly why. First, the turbo increases the intake pressure above atmospheric pressure. Second, the turbo heats up the intake air above ambient.

Depending on your level of determination, you could try contacting someone at Andial (the Porsche people.) They routinely build and rebuild turbo Porsche racing engines and may have some tips for you. Sorry I could not be of more assistance.

Best Regards
Greg Woo<ul><li><a href="http://www.andial.com">http://www.andial.com</a</li></ul>