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howdy yall. I have just got a quote to get an alloy prop shaft made rated at about 450hp. it will save 6kgs and maybe 10whp. for 850 dollars this seems like a much better mod then an exhaust system on paper? less stress on the rest of the driveline etc. what do you guys think?

Padawan Leaner: "Master Wun would prefer if you just went the whole hog and got a carbon prop shaft. That would be more than $850 dollars so it will make your wallet even lighter. Am I getting this right Master Wun?"

Master Wun replies: __________________________________________________



Sorry 16bit for going off topic - I really couldn't resist mate

funny you ask - I got a quote for a carbon propshaft. Minimum 1800bp - yes thats british pound not miss the hp for bhp.

Padawan says: "Master Wun would like to know the weights of the standard, alloy and carbon prop shaft in kilograms. Money is not important - only lightness is important."

16bit wrote: it will save 6kgs and maybe 10whp.

So how exactly does a tube save 10 Hp??

Maybe it has less inertia and allows the car to accelerate like it has ten more Hp but I doubt it would "add" 10 Hp to any steady-state dyno test.

M

alloy propshaft...

havn't heard about that since GranTurismo1

I'm only guessing, but I would say that the lighter propshaft would gain some of the horsepower lost between the engine and the rear wheels. It certainly wouldn't give the engine a gain but could make up some of the loss through the drive train. For example a boat dríven through a stern leg looses approx 25% of its horsepower through the two 90 degree crown and pinion joints in its driveline. An outboard motor has only 1 joint ,so looses less. A conventional shaft drive looses the least horsepower. I guess what I'm trying to say is that between the gearbox and the rear wheels there could be a gain with some outside the square thinking.

Same way you gain HP by bolting up some light wheels...

yes you don't gain hp. you simply limit your loss. hence why when you dyno your car and get a read out that is 30rwkw less then the factory figure.

group buy???

possibly - will have to enquire.

bumpity

me and hell are tempted... alot

16bit wrote:yes you don't gain hp. you simply limit your loss. hence why when you dyno your car and get a read out that is 30rwkw less then the factory figure.

I'd like to see a 'before and after' dyno chart before I put my money down...

If I had $800 to put down, Id do this just to bloody different! would it affect torque in anyway?

Also, does a prop shaft count as sprung or un-sprung weight? it connects to both, which would it affect the most?

I have never been a racer but i hear reducing un-sprung weight is where you will gain the most handling via weight reduction improvements?

madboy wrote:If I had $800 to put down, Id do this just to bloody different! would it affect torque in anyway?

Also, does a prop shaft count as sprung or un-sprung weight? it connects to both, which would it affect the most?

I have never been a racer but i hear reducing un-sprung weight is where you will gain the most handling via weight reduction improvements?

Forget sprung vs un-sprung in this case. The difference is requiring less of your engines precious power to actually move it. You loose power with everything that your motor has to turn, if you make it lighter, ie engine internals, flywheels, clutches,tailshafts, diff centres and gear and driveshafts, then the theory goes that more of your engines power, can actually get to your wheels - where it's preferred. A good example is a Ford 9 inch diff, which requires 40hp to actually turn on a car....this concpet is why the 1.6 MX5, has such a pissy little diff - less power to actually turn it.