Go Back   LS1TECH > LS1-LS2-LS3-LS6-LS7 PERFORMANCE > Advanced Engineering Tech
Sign in using an external account
Register Forgot Password?

Advanced Engineering Tech
For the more hardcore LS1TECH residents
Sponsored by
Whipple Super Chargers

Horsepower loss due to driveshaft weight?

Thread Tools Search this Thread
Old 07-01-2010, 09:33 PM   #1
10 Second Club
Garage is empty, add now
htownws6's Avatar
Trader Rating: 1
Join Date: Dec 2009
Posts: 97
Default Horsepower loss due to driveshaft weight?

Has anyone ever calculated what the HP loss would be on a heavier driveshaft over say...a stock driveshaft?
htownws6 is offline   Reply With Quote
Old 07-01-2010, 10:44 PM   #2
On The Tree
Garage is empty, add now
b.d.d.'s Avatar
Trader Rating: 2
Join Date: Jun 2008
Location: Central IN
Posts: 155

Depends if you are talking true reciprocating mass where one side is weighted more than the other, or more of what I would call static mass where everything is equal.

I've experimented with heavier flywheels and / or lighter driveshafts with the intent of maintaining torque when a load is aplied or when the gas is eased off and back on again. Pretty much a waste of time.

Some things make sense on paper, but fail to deliver results on the track. In theory a lighter driveshaft would be better, but I have doubled the weight of my DS and not lost or gained anything.
2000 NHRA T/A
2002 B4C NHRA Stock Eliminator Camaro
1969 440-6 Super Bee
1971 440-6 Cuda
1983 CJ8 Off Road Command Vehicle
b.d.d. is offline   Reply With Quote
Old 07-06-2010, 01:24 AM   #3
TECH Resident
Garage is empty, add now
Trader Rating: 0
Join Date: Dec 2004
Location: K-W, Ontario
Posts: 844

Are you trying to determine static loss, or losses during acceleration?

I don't think you'll find any difference in steady state RPM, however
accelerating, or decel will be effected by the mass of the driveshaft.

It's such a small diameter that it may be negligible unless you're looking
for that last bit of performance from the driveline?
Welcome to the Internet, where everyone's a mechanic and has a 10 second car.
GTM #105, 6spd, G96.00. Modified LQ9
Adrenaline_Z is offline   Reply With Quote
Old 07-06-2010, 08:28 AM   #4
Internet Mechanic
2002 Pontiac Trans Am
BlackScreaminMachine's Avatar
Trader Rating: 17
Join Date: May 2005
Location: Wallingford CT
Posts: 9,832

Simple answer would be to say that a Stock Aluminum DS may accelerate quicker or by that thought decel quicker but will break when FORCE is applied at launch.

Consequently a 3" Steel DS may sap some power compariatively but virtually guarrenteed not to break in most situations.

I would rather lose 5hp and not break and have the potential to win the Race or Event.
2002 NBM Trans Am SOLD!

BlackScreaminMachine is offline   Reply With Quote
Old 07-06-2010, 12:40 PM   #5
2002 Chevrolet Camaro
jimmyblue's Avatar
Trader Rating: 11
Join Date: Mar 2002
Location: East Central Florida
Posts: 12,312

Horsepower loss is bullshit. You feel that driveshaft getting
hot? No sir. It's only storing energy in a form you don't

Calculate your rotating kinetic energy at trap speed, divide
it by your ET, and that's how much "horsepower" rolled up
went into rotary rather than forward motion across the 1/4.
Lot of messy detail to get it reasonable but you could call
it a hollow cylinder of 1/8 wall, measured diameter, holding
all the scale weight. I'm sure Wiki would turn up the formula
for moment of inertia and rotating KE for a cylinder on-axis.

2002 SS convertible

SLP Blackwing lid, 85mm MAF, 85mm Professional Products intake & TB, SLP CME, JBAs/Mufflex tubes . SLP Y, McCord cutout, Fuddle 3500/2.0, GM truck pan, '98 flexplate, 3.42s, T-2R, MAC cover, welded tubes, Hotchkiss PHR, springs; BMR bolt-in LCA brackets, K-member; UMI TA, boxed stock 1LE LCAs, SLP Bilstein / Gabriel air shocks (F/R); Strano 35/22 sway bars, 224/224 116 cam, LT1 rad, HPTuners 12.6@112MPH
jimmyblue is offline   Reply With Quote
Old 07-07-2010, 06:58 PM   #6
Teching In
Garage is empty, add now
FSAE_Junkie's Avatar
Trader Rating: 0
Join Date: Oct 2009
Posts: 47

How much torque in what gear? That is the important question. The horsepower that makes it to the wheels from the engine depends upon how quickly you are accelerating the driveline or what gear you are in - along with how much power you have and how much your car weighs.

I can tell you this, changing driveshaft weights or Moment of inertias will have pretty much no effect in any gear other than 1st. Even in 1st gear, I would say its around 1 to 2 lb-ft gained by dropping 20 lbs or so.

Losing weight in the flywheel would be much more advantageous. In 1st, the flywheel will be weighted roughly 10 times more. i.e. removing .1 kg-m^2 of inertia from the flywheel will be like removing 1 kg-m^2 from the driveshaft. Then you have the fact that the drive shaft inertia is only about .05 kg-m^2 worth of inertia and you realize that pulling about 2 lbs out of the flywheel will be like completely removing ALL effect of your driveshaft out of the system.

Here is some hard numerical data for changes in flywheel weights from the following: http://www.ls1gto.com/forums/showthread.php?t=356153

Originally Posted by FSAE_Junkie View Post
So, I have spent the last few days pondering on what clutch to buy and what flywheel to go with. So I figured I'd compute what the torque gain for each gear would be to see if it'd be worth going with the lightweight flywheel.

So, I drew up a basic flywheel in Solidworks and adjusted the thickness until it weighed 28 lbs and then found the polar moment of inertia. I did the same for the 18 lb flywheel. They were aproximately 0.17 kg-m^2 and 0.11 kg-m^2.

Here are my results (using peak torque of 410 ft-lb):
2nd and 3rd columns are how much torque (lb-ft) the respective flywheel eats up.

Gear | 28 lb Flywheel | 18 lb Flywheel | Torque Gained
1 | 41. | 27. | 14.6
2 | 20. | 13. | 7.1
3 | 9.6 | 6.2 | 3.4
4 | 4.7 | 3.0 | 1.7
5 | 3.3 | 2.1 | 1.2
6 | 1.5 | 1.0 | 0.5

This is assuming 3800 lb race weight (yes this matters). Peak torque of 400 lb-ft. 3.46 final drive.

If the final drive goes up, weight goes down, or you make more torque, the gains from a lightweight flywheel will be more noticable. For example, just 3.91's on the same setup would yield a 2.1 lb-ft gain in 4th (instead of only 1.7 lb-ft).

As you can see, the gains are most noticable in 1st, 2nd, and 3rd. The equivalent hp gains in each gear will be very similar to each torque gain.

For the money ($50), this isn't a bad deal.

Personally, I was just worried about driving on the street with a sticky 6-puck clutch and a healthy cam, so I went with the stock weight flywheel.

Hope this helps other people make their decision on which way to go.
FSAE_Junkie is offline   Reply With Quote
Old 07-07-2010, 06:58 PM
Pontiac Firebird

Paid Advertisement

Similar Threads
Thread Thread Starter Forum Replies Last Post
350z LSX swap kit 10camaross Parts Classifieds 0 08-05-2012 05:03 PM
Buying back a total loss dave70 Paint & Body Work 15 03-31-2011 11:27 PM
Loss of rwhp thru Borla Plate Exhaust System? OLDSCHOOL85 Dynamometer Results & Comparisons 10 12-07-2008 11:13 AM
drivetrain loss for th350 th400 and 4l60e Formula_Power Automatic Transmission 0 09-06-2007 11:03 AM
aluminum vs steel drive shaft 1999 SS Gears & Axles 17 07-26-2006 03:00 PM

2002, drive, driveline, driveshaft, energy, engine, flywheel, horsepower, lbs, loss, losses, lost, power, shaft, stock, torque, trans

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are Off

Join Ls1Tech

All times are GMT -5. The time now is 07:39 AM.

Powered by vBulletin® Version 3.8.7 AC1
Copyright ©2000 - 2015, Jelsoft Enterprises Ltd.
Advertising - Terms of Service - Privacy Statement - JOBS
Emails & Contact Details