[SpecG]

How can I calculate WHP from MAF readings?

Let say my 76mm intakes are reading max of 230g/sec and 220g/sec on each banks.. OEM is 65 or 66mm intakes if i remember correctly.. does fuel multiplier affect this calculation?

 

[thistle]

You can't really since your g/s readings are skewed by the new intakes. Even on stock intakes, you can achieve different WHP per g/s depending on AFR, ignition timing, air temperature, coolant temperature, octane, and the dyno on which you want your WHP, but some work on the basis of 1WHP per g/s as a very rough rule of thumb.

Similar arguments apply to fuel, but some suggest 5.5cc per flywheel HP for a typical turbo engine, but there are so many variables.

 

[SpecG]

Thank you Thistle..I kind of understand that it ll be very rough estimate.. but as you mention those variables are quite a few and makes the estimation pretty useless but nonetheless.. still something to feed the mind before taking the time to dyno

so for the rough estimate for 76mm intake, I just need to multiply the total g/sec x (New MAF area/OEM MAF area)?

Cheers

 

[thistle]

The ratio of cross sectional MAF areas as you propose would work if things scaled like that. Sometimes they do, sometimes not, depending on the intake and even installation.

If you have stock MAF curves then you could multiply up the g/s by the ratio of the new and old fuel multipliers, assuming you have not lied to the ECM about the true injector size IYSWIM.

 

[SpecG]

If you have stock MAF curves then you could multiply up the g/s by the ratio of the new and old fuel multipliers, assuming you have not lied to the ECM about the true injector size IYSWIM.

I am using stock MAF curves..but I have slightly lied to the ECU about my injectors.. so my fuel multiplier isnt exactly 1:1 to other parameters.. so for the simplicity I just thought using the new and old maf area would be the most simple one... but wasnt sure how rough it was thats all.

Thanks for taking the time to respond though.

 

[thistle]

You should be able to factor in the lies re the injector scaling and the adjustment to the fuel multiplier in simple ratios. If your MAF curve is near stock and your AF corrections are tight then it will give you a reasonable guide to mass airflow.