Simple...Does a limited slip differential cause car to lose horsepower on the dyno? if so why?

 

No, the dyno is just a big drum that spins both wheels, and an LSD will not come in to play at all.

 

Yes it does. Depending on the LSD type, the extra drivetrain losses consume about 3-5% of power to the wheels.

Andrew

 

I was thinking of getting a quaife LSD. I heard that it will make you lose about 5-6 whp

 

Yeah that sounds about right... Different LSD types could cause even more drivetrain losses. e.g.: Viscous type LSDs would cause even more drivetrain loss.

But then, who really cares what numbers your car can pull on a dyno if you can't put that power to the ground with your peg-legged stock differential?

Andrew

 

are honda lsd's viscous or clutch type?

 

I'm pretty sure they are neither. I think the Hondas usually have a gear type LSD. e.g.: The ITR has a planetary gear type LSD, same with the new CL TypeS manual's LSD...

Andrew

 

I have a OEM JDM lude LSD - so I'm loosing about 6hp to the wheels with it? or even more?

 

I have NO IDEA how this is going to 'Lose' horsepower on a dyno, a dyno spins both wheels at the same time on a drum, the diff will not come into play at all, how will you be loosing horsepower? I can't see how this is possible, I believe this is misinformation.

As for loosing horsepower in the 'corners', I would say that's BS as well, because the traction you gain from having the LSD will offset any 5-6 horse loss, massively!!

 

"a dyno spins both wheels at the same time on a drum"

You've got it backwards, the tires spin the drum.

Michael

 

Sorry- thanks Mr.English Professor ! I should lay off the SWED...
lol


[Modified by kevie88, 4:32 PM 4/21/2002]

 

Again, an LSD results in more parasitic losses to the drivetrain than an open diff. Any time you add additional mechanical parts for the power to be transmitted through in the drivetrain, it will reduce power to the wheels. More gears to turn = more power converted to friction, heat, and noise = less power getting to the wheels on a dyno.

Andrew

 

Yes! It works on the same premise as manual hp vs. auto hp. A car with a manual tranny will usually dyno slightly higher numbers than one with an auto because the auto has more moving parts and more places where hp is lost. Basically, the more that is moved, the more hp is lost.

 

This argument does not make sense, you need to look into how a differential works. http://www.howstuffworks.com/differential.htm

In a straight line, there is no 'diff' effect, (ie: both axles are turning the same speed) the axle acts as a locked unit and turns as one, Therefore you cannot lose horsepower from it! The only parasitic loss will be from the extra weight of the clutches or gears (at the most 1 or 2 lb) which is located so close to the center of the axle it would barely affect anything at all.

 

Also, an LSD unit usually has a smoother housing than an open diff, which would decrease parasitic loss from oil displacement.

 

The ITR LSD is a helical gear type. The aftermarket LSD such as the Kazz, Mugen, and Spoon are clutch type and give off the resultant chatter at low speed, also b/c they are clutch type, the LSD's will eventually wear out, or rather the clutch disks will, that is primarily why the OEM LSD's are now helical gear; greater service life w/ minimal maintenance. Honda also used the viscous type LSD's in the JDM XSi Integra's and EF8's.

Hope this all makes sense.

 

Honda's H22A factory LSD is a clutch type.

 

..I didn't know. Thanks.