Torque multiplier?

[dojobi]

Hi all,

I just had my car tuned at Hills (awesome tuner btw - thanks to all who recommended them) and got 177rwkw, which I'm damn pleased with. I'd like to know what my torque is though, but the car was dyno'd in 3rd and is giving me insane numbers. I think I saw a thread on this a while back but noone actually said how you can convert the number to the real torque.

Anyway, you can get my dyno sheet at www.ozemail.com.au/~caddies

Anyone know?

I'm sure it's got something to do with the 1.3:1 gearing on 3rd, but dividing by 1.3 certainly isn't giving me correct numbers.

Cheers,

Michael

[dojobi]

Anyone? Anyone?

[b2barker]

kW = (Nm x rpm) / 9551

Nm = (kW x 9551) / rpm

[dojobi]

Ahh, thanks. I can now work out what my torque is, which solves my problem, but I would like to know the maths behind my dyno graph. I mean, why does 3rd gear really inflate the torque numbers so much? Any ideas?

[kjb_r33]

because its a ratio, 1st gear would inflate in more..........

and you also have differential ratios so it jump again...

[dojobi]

Yeah, I realise that it's a multiplier, but I was just trying to work out how it all relates, as dividing my torque by the multiplier for 3rd gear didn't change it. I also tried compensating for the diff, and that was still off.

Cheers,

Michael

[JimX]

Yeah I'm still interested in figuring out the flywheel torque too

Out of interest what mods have you got and what boost are you running? My intercooler plumbing is killing my power, I'm going to get that sorted early next year. Every mechanic that sees the way the pipes are hooked up with right-angle bends gives me a worse reaction and a bigger speech on how crap it is. Mark's was the worst

[ron]

hi,

[ron]

hi,

177rwKw@ 14PSI. that s excellent.

what mods do you have?.

i got 170@10PSI. would i get much more with 14PSI??

i have stock ECU& injectors.

ron

[b2barker]

OK I think I have nailed it. I think the answer to your original question is that your dyno is showing 2.33 times the flywheel torque after losses(I will explain what I mean by that later). I don't know why it's 2.33 but I will explain how I got there.

Firstly the I have used ratios from here which I think are correct. My car redlines at about 100km/h in second so I know the first one I had was wrong. So using this your max power at 129km/h is 6157 engine RPM, which seems fair. At this speed your wheels are doing 1084 RPM. Now given that kw=NmxRPM/9551, that means with 177kW the torque at the wheels is 1559.7Nm at the wheels. Thats impresive.

So I think what the dyno operators do when they set it to display torque at the wheels is reflect this back to the flywheel. eg. Torque=Nm@wheels/(Gear Ratio X Final Ratio). That would give you 274.56Nm at your peak power (you get the same figure if

you put 177 and 6157 into the Nm=kwx9551/RPM formula where RPM is engine RPM). This again seems fair because the torque at peak power at the fly with stock 184kw@6400RPM is 274.59Nm. So you are making about the same torque at the wheels as a stocker at the fly, but slightly less power at the wheels than stock fly power due to the fact your peak is at slightly less RPM.

Here is the spreadsheet with the right gearing. You can put in you tyre stuff, different speeds and power to find torque.

[dojobi]

OK, here's a full list of my performance mods -

* HKS Type S FMIC

* HKS Cam Slide Pulley on the exhaust camshaft - 2 degress retarded

* Trust Airinx Pod Filter

* 3" front/dump combo pipe with a separate wastegate line, all HPC coated.

* Fujitsubo twin 3.5" catback exhaust

* Apexi Super AFC

* GFB Bleed valve (14psi)

* GFB Hybrid BOV (not really a performance mod, but it could affect how the car runs I suppose)

I think that's it.

Cheers,

Michael

[dojobi]

b2barker,

That all makes a lot of sense. I am glad we finally got this all sorted out. I might copy and edit my dynosheet's Torque scale on the left to reflect what it should be. After all, even if I get it slightly wrong, I'll at least be closer to what it should be.

Cheers,

Michael