This is a very simple way to mathematically ESTIMATE the new engine horsepower after ECU remap.
X * Y / Z = HP
where: X=RPM where max power occurred, Y=NM where max power occurred, Z=factor(7120), Hp=new horsepower
Looking at the factory dynamometer charts below you can see that:

VAG 1.9 TDI 115hp 4000RPM * 200NM / 7120 = 112HP

VAG 2.0 TDI 140hp 4000RPM * 245NM / 7120 = 137HP

PSA 2.2 HDI 136hp 4000RPM * 245NM / 7120 = 137HP

Fiat group 1.9 JTD 190hp twin turbo 4000RPM * 335NM / 7120 = 188HP

The above mathematical estimate is very close to the factory charts. So we can use this formula to get a good estimate for the new engine HP. The way we do this is to look at the Torque Limiter map in the tuned file and use the raise in %. Some torque limiter maps use actual desired injected quantity, some use NM as units. No mater the unit used you should look for % of increasement. So if we originally have 245NM and we raised the torque limiter by 25% at 4000 RPM we get: 4000*306/7120=172hp(for 2.0 TDI & 2.2HDI engines). Just raising the torque limiter map will not make more HP. You must correctly raise a lot of other maps that control the fueling and airflow to the engine. More fuel without air will just make smoke and no power. This is why you must log the car with diagnostic equipment, to see the actual airflow and injected quantity of the engine.

Very useful infos for beginners liek me. Thanks.

Thanks for this one.

Regards

i am working with VAG 1,9TDI-PD 115hp at the moment and at maxHP rpms (4000) it injects 43mg of fuel, with original setup. So i think for this engine rough estimation could be 200/43=4,65Nm/mg of fuel.
At same rpm with my tun1 software i inject 50mg, so 4,65x50=232,5Nm. And now using rpm freak formula> 232,5x4000/7120=130hp. So +32,5Nm and +15hp @ 4000rpm 8-)

RPM Freak formula don't work in my car... :?:

i have bmw 120d
stock car have 163hp at 4000rpm and 340NM, so 4000rpm*340nm/7120 = 191hp and this is not correct because stock car have 163hp

zotto wrote:RPM Freak formula don't work in my car... :?:

i have bmw 120d
stock car have 163hp at 4000rpm and 340NM, so 4000rpm*340nm/7120 = 191hp and this is not correct because stock car have 163hp

You don't understand how it works 8-)
340Nm is at ~2000 rpm, not 4000.

There is also a good way how to measure HP after tuning if you own VAG-COM diagnostic interface. All the info about you will found on this link by downloading "block 120 spreadsheet" excell file:

http://www.ross-tech.com/vag-com/cars/index.html

Regards,

Fred

For VAG cars there exit a tool (KPower) for HP and Torque. You must log meassure block 5 and 6 (diesel engine) and copy in this programm and you become a diagramm. Sorry for my english.

thank you very much

thank you very much