Bhp & ftlb torque Question to the mappers

With the 4 wheel drive how do you work it out 20% 22% 24% ? The MlR boy's go by the 24% rule. I think it's wrong!

[Scott.T]

Each make/model is different.
The rolling roads that do not do a run down to work out transmission losses just use a calculation based on a known vehicle.

i.e they have transmission loss data on a representative subaru or evo and just apply the same maths to the next subaru or evo that runs on the rollers.

i would dig out some old graphs but gave them away with the car.

http://www.lancerregister.com/showth...astdown+dastek

If you can find some EVO RR plots showing ATW and ATF fromthe same car on the same run, you should be able to calculate the appeox losses.

the above link talks about 24% i.e multiply ATW x 0.76 and that this gave correct figures for stock cars.

[Jolly Green Monster]

Originally Posted by Nige

With the 4 wheel drive how do you work it out 20% 22% 24% ? The MlR boy's go by the 24% rule. I think it's wrong!

dyno dynamics use a fixed percentage (ignoring environment influences - atmospheric pressure, air temp, intake temp etc).. 22% iirc in shoot 44 mode for 4wd... no matter what the car is etc.. there are influences on that further with regard to rpm pick up and where calculated at a speed divided by rpm etc..

other dynos like dastek for example uses a measurement at half to full throttle at 3000rpm to take a measurement of speed v rpm and tyre defomation and then records drag on the overrun..

I use both dastek and dyno dynamics a lot, I tend to be judging it from a different view point to your question is asked.. ie. I am mapping a car for the road.. not just to get biggest figures or whether they are correct per say.. obviously they give an indication and are used in setting a car up.. ie. it makes more power on this run after changing x y and z therefore it is adventageous to change them etc..

Its easy to get hooked up on figures..

Simon

I was asking on here because ive got pm's from MLR guy's asking how my car did on the dyno. I can only tell them atw figures. Some are asking for atf figures so just trying to answer.

[Jolly Green Monster]

I see.

A lot of people in the evo world use the wheel figures.

Just tell him "in the region of" and use the % you are happy with?

What did it make at the wheels and what is the spec now?

You could pop up to surrey rr or another dyno dynamics and get a power run to see out of interest. You would get a print out of wheel and fly then.

Sounds a monster regardless Nige :thumb:
Simon

[Jolly Green Monster]

Nice.

What turbo you on now?

Fp black. Still only 2litre so ftlb torque is good. That was on 97ron & a 3 bar map sensor need a 4 bar. I got it so it gave me a bigger power band to play in & not for outright figures. Now i have to turn it down as the clutch cant cope.

[Jolly Green Monster]

dunno how the FP stuff manages to work on the evo's, it really doesnt on the subarus.

looks very nice.

why 97ron??? lol

what boost is that at?

Just in case i cant get 99 ron at any time. Boost was safe at 2 bar now at 1.5 due to clutch. Once clutch is sorted & a 4 bar map sensor fitted in there i might wind it up a tad. That wont be untill the winter.

[Anger]

Cant you have more than one map Nige