Hi,

I'm looking for suggestions on how to reduce transmissions losses (increasing power at the wheels).

given that the impreza general looses around 24% from the flywheel...

What would need replacing ?

Lightened Pulleys
Lightened Flywheel
Clutch

Carbon propshaft

What else ?

thanks,

 

I'd say you're pretty much covering the easiest and most effective basis there

Maybe lower profile tyres and light weight wheels to reduce rotating mass as well

 

Your losses are mainly the losses from lossy dynos and the situation is nowhere near as bad as it might seem.

If you run on a Dastek dyno, you'll find your coastdown losses are more like 12 or 13% on a Subaru or Evo.

 

There are 2 technical areas here
1
The above mod change the intertia of the system. Doing these mods gives an easier time on the engine during accelleration (on road or RR) as it has less mass of those components to get up to speed. The car on the road will accellerate faster after such mods using the same engine/conditions etc.
2
The tramsmission losses are the sum of friction/drag/tyre deformation and many other factors that are there robbing the engine of power as the car is accellerated or held at a chosen speed.

To reduce these losses to a minimum is every engineers goal/dream, but I think John's words are wise and correct.
I think it fair to say every RR is different even when recently calibrated, so only give an indication of a powertrain at a given (moment in) time.

To get true power /torque of an engine you need an engine dyno...bet there are several caviats(sp) to those as well!

Graham.

 

If your minted you could always go for a straight cut gearbox. Just buy a good pair of ear defenders.

Jase

 

0w-20 oil in the engine, diff and gearbox.

Seriously though, don't do it

 

I don't think there is much anyone can reasonably do about the trans losses. Subaru will have spend a zillion Yen making the system as good as it (commercially) could. I doubt that anyone of us can improve significantly on their work....

Graham

 

ok thanks for your comments guys

 

Finally the true identity of pslewis is revealed!

 

I’ve found this site while looking for bits for my race Renault.

http://www.gearboxman.co.uk/psservices.html

I have not spoken to them, so I don’t have any idea of prices or the quality of service they provide but if you are serious about reducing transmissions losses then the section about on 'Shot-peening and polishing' maybe of interest.

Paul.

 

Carlos! That's not fair....but looking back it does read a bit like PL's threads doesn't it?

I hope you all see what i'm saying.

Subaru (Rover/BMW etc) all must make transmissions as good as poss to gain on emmisions/fuel consumption audits, but also have to keep a keen eye on the costs.
Bet Prodrive can save a bit on losses, and have the bills to prove what they have changed.

Graham

 

We used to run race cars [ very successful ones ] on a pint of automatic transmission fluid only in the gearbox. frictional losses in the gearbox were much lower and there was no damage to the gears or bearings.

Most cars only ran 12 or 15 laps in a race but in all weathers and all temperatures. The oil was changed every race and the boxes were rebuilt every three. But none was ever damaged by the low rated oil.

Possibly an idea for a track car in a shootout situation or for 1/4 mile stuff, but not for general road use. IE; competing daily drivers.

David APi Engines / APi Impreza
www.apiengines.com

 

Some manual transmissions run ATF from the factory.

Ford's MTX75 being one of them. Although, I suppose they aren't "that" ok really in terms of durability, are they?