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The mkiv Supra Owners Club

Transmission losses


Dnk
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I'm not looking for exact figures but whats the general consensus

on how much the stock tt autobox loses from flywheel to wheels.

 

I'm guessing its between 15-20 % so if you had a 400 fwhp figure

 

at worst you would have 320 at the wheels 20% loss

 

and at best 340 at the wheels 15% loss

 

Any links to previous discussions please post them up

Edited by Dnk (see edit history)
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SRR use 20% loss for the autobox.

 

Really, that much? So a 1000fwhp will loose 200hp to the wheels? Thats a whole NA supe! Does torque converter make a difference as higher stalls are alot smaller carrying less fluid?

 

Whats the average loss for a manual or isnt there one?

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Here you are, Dave Baker was a real professional but lost heart with the job as companies with rolling roads were inflating power figures to create work and reputation.

 

http://www.max-boost.co.uk/max-boost/internet_articles/Puma%20Race%20Engines%20Technical%20Guide%20-%20Measuring%20Engine%20power%20-%20engine%20dynos%20and%20rolling%20road%20dynos.htm

 

and

 

 

http://www.pugheaven.co.uk/Transmission%20Losses.htm

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Here you are, Dave Baker was a real professional but lost heart with the job as companies with rolling roads were inflating power figures to create work and reputation.

 

http://www.max-boost.co.uk/max-boost/internet_articles/Puma%20Race%20Engines%20Technical%20Guide%20-%20Measuring%20Engine%20power%20-%20engine%20dynos%20and%20rolling%20road%20dynos.htm

 

and

 

 

http://www.pugheaven.co.uk/Transmission%20Losses.htm

 

That's a good article Chris. Seems reasonable albeit a guesstimate.

 

So at 1 bar my car made 335rwhp which equates to 392fwhp, sounds fairly accurate.

 

Max of say 12-14% transmission losses on a manual.

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That's a good article Chris. Seems reasonable albeit a guesstimate.

 

So at 1 bar my car made 335rwhp which equates to 392fwhp, sounds fairly accurate.

 

Max of say 12-14% transmission losses on a manual.

 

So what would of my dads been, It made 443rwhp and its an auto?

 

Any ideas after you read that whole post :) Lol.

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Cheers guys, Not to bad. I find it odd how every dyno reads different. A couple of weeks back it made 553.0fwhp at SRR

 

Well just that article alone regarding tyre pressures is very interesting. Huge difference when psi is dropped as wheels sap the power if under inflated.

 

So many variables. I'll be going by pure RWHP in future with the right setup.

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Maybe the autobox saps 25% of the flywheel power :confused:

 

As above and that article mate just too much guess work. Only true way to measure is to run RWHP and then engine dyno on exact same conditions and variables. At least then you could accurately measure the difference giving you your tranny losses.

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As above and that article mate just too much guess work. Only true way to measure is to run RWHP and then engine dyno on exact same conditions and variables. At least then you could accurately measure the difference giving you your tranny losses.

 

That sounds the best way mate. Will have to get my car on the dyno measuring fly and wheel power.

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They would of had to estimate it I would imagine. If they did the in neutral coasting tactic to find out potential losses as per the article it's not accurate as no power is running through the drivetrain.

 

Have you got your dyno graphs available?

 

Who me or Chris?

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