Transaxle vs regular transmission question

[Roger Vincent]

I am no mechanic. But I was wondering if a transaxle allows more hp to the rear wheels in comparison to a regular transmission. Any answers? The reason I am asking is that I read that a lot of guys seem to get dyno readings of 535 at the wheel, and Ford says the engine puts out 550. Wouldn't we lose about 15 percent normally from engine to wheel, which if that is true, we should be getting about 470 rwhp, right? What am I missing here?

 

[BlackICE]

I think Ford was conservative on the HP rating and the transaxle is probably more efficient too.

 

[OCPETE]

Anyone knows that direct power to transaxle is Ferrari / Porsche ass end advantage over a front to rear driveshaft, not to mention mid point weight /handling characteristic advantage over anything :thumbsup

 

[Empty Pockets]

The transaxle should be the better deal HP wise - all else being equal - because there's no additional HP loss spinning a heavy drive shaft.

'ICE is right.
The "story"(?) on Ford's HP declaration I read (here on the Forum somewhere I think) was that there are states in the U.S. that won't allow the sale of street driven vehicles with over 550 H.P. Sooooo, I guess Ford wasn't really "lying" ... because the GT's RWHP IS about that!:thumbsup

 

[nota4re]

My opinion is that Ford had no reason in the world to be conservative with the HP ratings - and I think the opposite would be a stronger influence. I also think that those that have had dyno readings (stock) of 520 or more were probably on a very generous dyno.

Perhaps the point is moot, however, as the primary point of a dyno run is not to do internet comparisons with other owners of similar cars. The main benefit is to obtain a baseline and then to have a method to see the benefits of your mods.

Back to your question..... I would thing that a transaxle is modestly more efficient (less HP drop) than a traditional transmission/driveshaft/differential.

 

[analogdesigner]

Just a quick note from the old drag racing days. A two- speed Powerglide automatic "eats up" about 20 to 22 HP. A three-speed Turbohydramatic 400 (TH400) due to it's extra gear and durability has about twice the losses. One more problem is that the rear end differenial has losses too.

Now, manual transmissions (have less losses compared to automatics) with "sychros" have more losses than the older non-synchro Indy car tranies. The problem with a non-synchro trany, is that it will shift like a worn out school bus unless you are really experienced. Most transaxles are probably the best compromise due to the tranmission and differential being combined into a single unit.

You do not loose HP spinning a driveshaft, however, the moment of inertia will usually be higher which is bad for acceleration. Also as mentioned above, if you have a driveshaft, it usually means that a rear end (with it's losses) is also involved.


Jay

 

[Roger Vincent]

Thanks for your information. I have a clearer picture now, and when folks ask the HP rating, I will simply say 550 according to Ford, and not "Well it could be a little more than 550 since most owners say their cars dyno at about 520 at the rear wheels." I just didn't want to stick my foot in my mouth, particularly with my Corvette brothers here in Bowling Green.