Drivetrain efficiency

Route666

Active Member
Aug 16, 2003
1,652
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39
Brisbane, Australia
Who here thinks about drivetrain efficiency?

I see a lot of threads on strokers and other things to make the engine more powerful but I'm also interested in getting more of that power to the rubber/bitumen interface.

In my search I've come up with aluminium and carbon fibre driveshafts, the obvious aids to decreasing energy wastage in the drivetrain.

I have also come up with titanium and aluminium (not as durable) pinion yokes - more rotating assembly lightening.

Here in Aus, we have 400hp four door sedans, turbo straight 6's in new Fords, as standard, (good on ya Ford Aus!) with more torque than any of our production V8s, but these cars weigh 1900kg (~4200lb) so getting 300hp (engine) in a classic mustang would equal one, and getting 400 through an efficient drivetrain would not only be relatively good on fuel, but also THRASH the nuts off of the new production cars. Not only that but I could build a 400hp classic stang for MUCH less than the 400hp variety of these things. So it has sexiness, unbeatable (well, there's always someone faster, but phh, they wasted their money lol)performance, and it would be not too much of an alcolohic.


I've also thought about getting gearbox and diff gears coated in low-friction oil-retentive coatings, but I'm not sure about the effectiveness of it. I guess this is because there is no evidence or testing of it. I'm sure it would be good for SOME loss, maybe 1%, maybe more, but it's still something.

Anyone else have any ideas, or is life too short in your opinion? lol

I look at it as: Would I rather a car that does 0-60 in 4 seconds or a car that does 0-60 in 4 seconds and costs less (in fuel) doing it.
 
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drivetrain efficiency is important. the biggest things you have to work on are rotating mass and friction. synthetic fluids, and lighter weight lubricants(where you can legitimately use them) help with the friction. reducing rotating mass by using aluminum tube for the driveshaft is also good. there are even carbon fiber driveshafts being built for the street, with the added benefit of reducing vibration transmission to various parts of the drivetrain.
 
Yes the fluids, there's another area where friction could be reduced. If you're running a torque-sensitive worm-gear type differential you could use a friction modifier with teflon since it won't effect the clutch discs in the LSD.
 
Something else to consider are straight-cut gears. They ar not only stronger, but eliminate alot of the sliding and thrust loading between teeth that helicals have. The down side is the extra noise. Dont forget an aluminum flywheel. You could also spend a giant amount of money on an aluminum pressure plate setup.

As for a 9" being so much less efficient than an 8, I dont see how it could be that different. The only real holdback is the weight of the rotating parts and even that would only largely affect acceleration, not cruising.
 
With the 9" have a larger rotating mass, on a larger circle (the energy required goes up by the square of the radius of the spinning object) it could make quite a difference. Also - I think it is going to have an effect on fuel efficiency even when cruising as it will take more energy (per unit time) to keep the things spinning. I guess, wrt mainly race cars now, that decreased drivetrain rotating mass also aids braking, and maybe cornering.

blkfrd aren't there two different ways of measuring horsepower? There are dynos that tries to hold rpm constant as the throttle in increased and use the braking force to calculate power.

Straight-cut gears are a good idea, nice addition shelbyclone.
 
Route666 said:
Who here thinks about drivetrain efficiency?


In my search I've come up with aluminium and carbon fibre driveshafts, the obvious aids to decreasing energy wastage in the drivetrain.

I was quoted $1100 for a composit driveshaft made of carbon fiber and metalized something or other from inland empire. That's 1/3 the way to a decent forced induction system.
 
blkfrd said:
Does the T5z

I think that 99.999% of all production transmissions ade in the last 60 years have helical gears. The G-Force can in fact be optioned with straight-cuts.

On the issue of dynos, an acceleration dyno measures acceleration over time. A water brake dyno measures peak torque as a load is gradually increased and horsepower is calculated from there.
 
jerry S said:
I was quoted $1100 for a composit driveshaft made of carbon fiber and metalized something or other from inland empire. That's 1/3 the way to a decent forced induction system.

That's true, the initial cost is up there, but say you end up with the same RWHP (not just from the DS, but overall) - reducing drivetrain loss is going to give you that power more "freely" - it'll take less fuel to give you the power, maybe not much, but over 2 years, 5 years, 10 years it'll add up. You would also be putting less strain on components overall, leading to less wear and breakage. That's not to mention that a CF DS (apparently) has a little give and reducing drivetrain shock.

I still love supercharged and turbo'd beasts but I really appreciate quality and efficiency. I kind of see it as the difference between brute force and calculated strikes - they both work but at differing costs. In war brute force costs lives on both sides and calculated strikes usually do not - usually destroying infrastructure instead, but taking more reconaissance and specialised equipment and skills.
 
remember currie has that 9" that uses 12 bolt gears or something and changes where the pinion and ring gear meet providing increased efficiency. personally i think i'll stick with my stock style 9" but i may go with an aluminum case and maybe lightened gears
 
the reason(or my understanding) of the 8.8 being more efficient than a 9 is that the center line on the 8.8 pinion is closer to center on the ring than the nine. assuming a ring gear is center on pinoin the gears would be straight cut, and the olny friction would be gear teath entering another. now with a lowered pinion the gears are now helical to eliminate noise but now the teeth slide on each other, the further down you go the more sliding you get. also the 9 has an extra bearing on the pinion, but that dont really equate to much
 
Ok I started a thread on this and didn't post my idea of a good efficient setup.

I have recently been developing a rear suspension system that could use a lot of TCP's existing hardware and also the customer's existing diff, without the large frame and cantilevers, simplifying it, thus making it cheaper to make, and lighter.

Anyway through this I realised I could not only get an aluminium carrier but a housing as well.

So my setup for efficiency with an engine not TOO powerful is a T5 with a CF DS, Ti pinion yoke (Strange), forged aluminium (Strange) pinion support.

Now the rear gears have to be conservative to maintain the efficiency as if they are too radical you'll be wasting energy spinning the driveshaft and transmission. Sure it'll be faster with 4.11's over 3.7's though.

Bnickel I've been looking at the Strange website (as you could probably tell) and they have a 12-bolt into 9-inch thing as well, I'll have to read it more closely. Currie uses Strange gear anyway so that's probably what it is.