[Blaiser]

Originally Posted by Rootus

I'd bet lunch a dyno test shows no difference. Changing the amount of rotating mass does not change the amount of power that actually gets to the ground, it simply reduces the amount of mass the engine has to accelerate. It would be like taking 50 pounds off the car and trying to measure that on a dyno . If you had a very, very heavy driveline, lightening it up significantly might change the dynosplot slightly by allowing torque increases to show slightly earlier. The amount of weight lost with a CF driveshaft is unlikely to show up as something identifiable.

I'll take that bet

i understand what you are talking about, but to me it only makes sense that this would increase hp and torque to the wheels....why wouldnt it, isnt that the purpose if this mod? the company claims 5% more hp on the whole curve...but no one has tested it, i would really like to see someone test this before i would consider buying it.

Also...people compare it to a TBE, that adds WHP...it has to add something is what im saying.

So, where do you live...when this is tested i want my lunch

[grim09]

ACPT will be dyno testing one of these shafts here in a week or two, wo we will see who will owe who a lunch.

[Mykl]

If there weren't so many people saying this thing made such a difference, I don't think I'd believe it. I guess I just don't understand how eliminating weight from certain parts of the drivetrain affects acceleration, and I certainly don't understand how changing a part that's behind the transmission can make shifting and throttle response better.

I can see how it could make a noticeable difference in the lower gears where the driveshaft isn't spinning very fast. But in the upper gears it takes less effort to get a heavy spinning object to spin faster, so it really confuses me to read that people are saying that it makes a large difference in 4-6.

[twiSTies]

Originally Posted by Rootus

I'd bet lunch a dyno test shows no difference. Changing the amount of rotating mass does not change the amount of power that actually gets to the ground, it simply reduces the amount of mass the engine has to accelerate. It would be like taking 50 pounds off the car and trying to measure that on a dyno . If you had a very, very heavy driveline, lightening it up significantly might change the dynosplot slightly by allowing torque increases to show slightly earlier. The amount of weight lost with a CF driveshaft is unlikely to show up as something identifiable.

I'll take that bet!

Reducing rotating mass from the drivetrain will allow for less horsepower to be lost driving the shaft, which means more power at the wheels. I've seen the benefit of lighter driveshafts doing just this on other cars.

So when the dyno shows a gain, wheres lunch going to be at?

[twiSTies]

Originally Posted by Mykl

I can see how it could make a noticeable difference in the lower gears where the driveshaft isn't spinning very fast. But in the upper gears it takes less effort to get a heavy spinning object to spin faster, so it really confuses me to read that people are saying that it makes a large difference in 4-6.

The upper gears don't have the torque multiplication that the lower gears do, so the engine has to work harder to maintain speed+higher amount of friction from air resistance, etc. It makes sense that people would feel a larger gain in the higher gears due to this, IMO since the gearbox isn't giving the engine as much help.

[Mykl]

Originally Posted by twiSTies

The upper gears don't have the torque multiplication that the lower gears do, so the engine has to work harder to maintain speed+higher amount of friction from air resistance, etc. It makes sense that people would feel a larger gain in the higher gears due to this, IMO since the gearbox isn't giving the engine as much help.

hmm, I hadn't thought about that trade-off...

Has anybody done a "before and after" drag strip run to test for an improvement in acceleration?

[La Mer]

Originally Posted by Mykl

hmm, I hadn't thought about that trade-off...

Has anybody done a "before and after" drag strip run to test for an improvement in acceleration?

someone used some sort of g-meter. that's all i know of. you'd have to dig for it.... I think it's towards the end of the orignal DS thread.

[Mykl]

Originally Posted by La Mer

someone used some sort of g-meter. that's all i know of. you'd have to dig for it.... I think it's towards the end of the orignal DS thread.

I'll have a look... but that thread is so large that it's almost useless.

[La Mer]

Originally Posted by Mykl

I'll have a look... but that thread is so large that it's almost useless.

it's towards the very end. i'll try to help you out.

[La Mer]

Originally Posted by La Mer

it's towards the very end. i'll try to help you out.

ACPT carbon fiber driveshaft, Thread #1

Here you go.

[Mykl]

Well, I'll keep this on the top of my list of things to buy. For power upgrades my car doesn't even have a downpipe, nor do I have an AccessPort. So maybe I'll just slot it in right after I do those upgrades.

[nhsilversti]

Originally Posted by Mykl

I'll have a look... but that thread is so large that it's almost useless.

OR you could have read the OP in this thread......

[Mykl]

Originally Posted by nhsilversti

OR you could have read the OP in this thread......

Thanks.

[nhsilversti]

Originally Posted by Mykl

If there weren't so many people saying this thing made such a difference, I don't think I'd believe it. I guess I just don't understand how eliminating weight from certain parts of the drivetrain affects acceleration, and I certainly don't understand how changing a part that's behind the transmission can make shifting and throttle response better.

I can see how it could make a noticeable difference in the lower gears where the driveshaft isn't spinning very fast. But in the upper gears it takes less effort to get a heavy spinning object to spin faster, so it really confuses me to read that people are saying that it makes a large difference in 4-6.

look at it a couple of ways

large heavy wheel and tire combos will decrease shown power on a dyno due to the power going into moving the heavy wheels. the power has to be used to FIRST get the wheel moving then it can use whats left to move the car.

a good old fashioned bicycle.....what can you pedal more easily(given same gear ratio is used)? a heavy fat tired clunker or a light weight skinny tire road bicycle.

the same principal applys to the drive shaft and the wheels (or any other rotating mass). if less power can be used to move the wheel, brake rotor or driveshaft then the power can be used to accelerate the car faster.

ted

[Blaiser]

I Want My Lunch!