POWERHOUSE driveshaft

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if the aluminum one is 600 and is only 17lbs, how is the carbin fiber one 1100 and is 20lbs. I know carbin fiber is more expencive then aluminum but isnt it lighter. Just what i thought.
 
It must be design differences and how much material they use in each one. The density of aluminum is indeed higher than that of carbon fiber. About 2.6 gram/cc for aluminum and about 1.75 for carbon fiber. So the carbon fiber shaft should be lighter if they both had exactly the same dimensions. I guess they must be using more carbon fiber (or more something else) in their driveshaft as compared with the aluminum version.

On the surface, it sounds a little goofy because carbon fiber is also a lot stronger (tensile strength at least) than aluminum or even steel.

So, you got me. I'm not an engineer, but I guess the BMR boys (who undoubtedly are engineers) are aiming for a stronger driveshaft.

One more consideration is the cost of $1100 versus the possible gain (maybe 15 HP) put it at $73 per HP. The $600 ones come out to be about $40 per HP.
 
As best I can tell from pics of the aluminum and carbon fiber shafts it appears the end yokes/flanges and adaptors are aluminum with the aluminum shafts but with the carbon fiber they appear to be steel. This might be the the reason the CF is heavier.
 
I read that the CF shaft was a duel layer lay out with the layers at different angles to ensure the shaft could handle the stress of the twisting motion without the shaft actually twisting itself....thats why it weighs a little bit more. It is suppose to be better at reducing vibrations then the alum one...but I dont know for sure.
 
They cost so damn much because the shaft actually has a splined section in it with a cv type boot because the transmission and rear do not have a slip yoke. So without the slip yoke, the driveshaft has to be able to change it's own length as the suspension moves. Plus these are a new model car and that automatically means they are going to bend you over when it comes to prices. For the record, my aluminum driveshaft does not have any vibration at all.
 
That's the big problem. These things cost a lot and don't give much gain. It might be justifiable for you since you're looking for tenths or hundreths of a second, but I'm looking for the most bang for the buck (I know I'm cheap, but I'm Scottish so its allowed) :)

For example, the combo of a CAI and a tune was expensive (for my pocketbook), but it was it was a pretty good deal at about $20 per HP.

I may still buy one of those driveshafts, but it is a little tough to go with something that costs maybe $50 per HP, or higher for the carbon fiber one.
 
My question is...how much hp do you think you're freeing up by getting the driveshaft and how can you measure that? faster timeslip with it in versus before you got it? I'm considering the same modification BUT I'm also not rich so have to get the bang for the buck like so many have mentioned.
 
hehe sounds like something I can wait on then.

Gonna save my money up for forged internals first then, maybe a modified crank someday to help safe the engine vs the poweradder I want to add once I'm back from lovely Iraq :)

Anyone know any great shops in the TN/southern KY area that can do some great work!?