Dyno differences

[Munch]

What is the percentage difference or loss for auto vs manual on the dyno?

[Sneaks]

They will both lose the same percentage from flywheel to rear wheel.
Do you mean which one, manual or auto, loses the most from flywheel to rearwheel?

[Z06PDQ]

I've heard 15% for standard tranny. is that about right?

[Y2Kvert4me]

Originally Posted by Z06PDQ

I've heard 15% for standard tranny. is that about right?

12-15% seems to be the norm.

I think A4s lose a bit more, not totally sure.

All I do know is I do not subscribe to the "fixed loss" theory presented to us by a popular aftermarket head manufacturer.

[Munch]

Originally Posted by Sneaks

They will both lose the same percentage from flywheel to rear wheel.
Do you mean which one, manual or auto, loses the most from flywheel to rearwheel?

Aside from your response being contradictory I believe it also to be hogwash. I say this with all due respect mind you.

I have heard that generally speaking manuals lose about 15% while autos lose about 20% from the flywheel to the tires.
Perhaps our resident tuner will chime in with his opinion.

[Sneaks]

Originally Posted by Munch

Aside from your response being contradictory I believe it also to be hogwash. I say this with all due respect mind you.

I have heard that generally speaking manuals lose about 15% while autos lose about 20% from the flywheel to the tires.
Perhaps our resident tuner will chime in with his opinion.

Dam Munch, you're right, it was contradictory. And what do you mean all due respect? There shouldn't have been any respect for that screw up.
I completely lost my train of thought there.......
On a chasis dyno, the autos lose more than the manuals by about 3% from what I've seen posted by guys that dyno their cars. But you know that's only going by similiar mods and numbers that were close to start with. I've never seen anyone take the same engine and dyno it through an auto car, then through a manual tranny car.
With the same gearing in the rear, why DO autos lose more than manuals on a chasis dyno?
Mind you I'm no dyno expert, and I did NOT stay in a Holiday Inn Express last night.

[1TZSLO]

With the same gearing in the rear, why DO autos lose more than manuals on a chasis dyno?

The gearing of the Tranny?

[Munch]

Originally Posted by 1TZSLO

With the same gearing in the rear, why DO autos lose more than manuals on a chasis dyno?

The gearing of the Tranny?

Cuz the power has to go through all "the magic" in the auto. Manual is clutch to gears, auto is magic juice to donut thingy to crazy stacks of parts and doohickeys and who knows what that crazy rat maze thingy with the balls and springs is!! Magic aint free, it costs horsepower.

You can tell I worked at AAMCO can't ya?

[Y2Kvert4me]

Torque converter is the difference.

No matter how "locked", they still have to slip some. Heat is generated, which means power is lost.

[Sneaks]

Originally Posted by Munch

Cuz the power has to go through all "the magic" in the auto. Manual is clutch to gears, auto is magic juice to donut thingy to crazy stacks of parts and doohickeys and who knows what that crazy rat maze thingy with the balls and springs is!! Magic aint free, it costs horsepower.

You can tell I worked at AAMCO can't ya?

Originally Posted by Y2Kvert4me

Torque converter is the difference.

No matter how "locked", they still have to slip some. Heat is generated, which means power is lost.

That's what I figured.

[Munch]

Originally Posted by Y2Kvert4me

Torque converter is the difference.

No matter how "locked", they still have to slip some. Heat is generated, which means power is lost.

Originally Posted by Sneaks

That's what I figured.

I said magic juice to donut thingy. Sorry if I don't know the fancy technical terms.

[Sneaks]

I knew what you meant Munch.

[allthrottleandsomebottle]

All magic.....12.7% manuals, 14.9% Autos..........I am working on have a local dyno day soon in Yorktown that will use a Dynapack.
Dynapack
We will eliminate some slippage issues me thinks....look for a thread soon

Munchles...........I have had the 97' on a few local ones, The stall STI & rpm also make an auto's #s crazzzzzzzzzy

http://temp.corvetteforum.net/c5/30s..._NUMBERS.shtml

[OBXFunn]

OK I have a question, is the percentage a constant number? Or does the percent equal a horsepower? How is that for confusing everyone? haha. I guess its like this, if a car makes 400fwhp and say there is 20% parasitic loss so the car makes 320rwhp. It takes 80 HP to run the motor, belts, etc. Now would the same car making 1000fwhp now need 200hp to run the motor, belts, etc or does the percent change?

[allthrottleandsomebottle]

Each vehicle WILL dyno different on each day at the same place.......all depends on mother nature. Each dyno is different just like each vehicle is different with the exact same mods........
The only way to know the exact % of loss is to have the motor FWHP known, say like Kevins........then go to different dynos and see what it reads. All dynos let alone types of dynos will read higher/lower. IMHE, the bottom line is the dyno is another tool() from a bag to use for gaging the gains/losses of performance on a given vehicle at a given time

[Y2Kvert4me]

Originally Posted by OBXFunn

OK I have a question, is the percentage a constant number? Or does the percent equal a horsepower? How is that for confusing everyone? haha. I guess its like this, if a car makes 400fwhp and say there is 20% parasitic loss so the car makes 320rwhp. It takes 80 HP to run the motor, belts, etc. Now would the same car making 1000fwhp now need 200hp to run the motor, belts, etc or does the percent change?

This is a rather popular ongoing matter of debate.

One side says it is a constant number (fixed hp loss), the other says it's a percentage.

A believe it has to be a percentage, as a power transmission system cannot possibly become more efficient with more power being transferred through it.

Sure, it takes x amount of power to overcome the frictional loads and drag within the drivetrain to turn it when unloaded (ie, not pushing the car), but with more hp input, and the power being applied to the ground, the actual load definitely increases.

A simple way to think of this, is take a 300rwhp car, run it WOT for a mile, and monitor trans and rearend temps.
Now do exactly the same with a 600rwhp car.

If you find the temps remained the same, then the fixed-hp crowd would be onto something. If the higher hp car created more heat in the drivetrain, then that additional heat produced was additional power lost.

Or, and even easier example...
We know a typical 350hp C5 dynos right around 300 at the wheels. That's 50hp, or 14% lost.

Now, look at the 638hp ZR1...From what I've seen, they are dynoing 540-550 at the wheels. That's ~90-100hp lost, but again, right about at 14%.. Go figure.

[DropTheTop]

Originally Posted by Munch

Cuz the power has to go through all "the magic" in the auto. Manual is clutch to gears, auto is magic juice to donut thingy to crazy stacks of parts and doohickeys and who knows what that crazy rat maze thingy with the balls and springs is!! Magic aint free, it costs horsepower.

You can tell I worked at AAMCO can't ya?

!!

[OBXFunn]

Vert, you are right about it becoming the "newest" debate. I just heard the HP story the other day and through it out there. I think you could argue both sides from now till the Redskins win a another Super Bowl and never find the solution. But Steve is ultimately right, the dyno is just a tool and nothing else.

[edcmat-l1]

Kevin's car/motor came out to about 13% drivetrain loss.

One motor we did that went in an auto GTO, was about 15% loss with the conveter locked.

I'm not a believer in a set % loss. Although it takes XX amount to drive a certain drivetrain, and that the amount goes up with speed, it cannot be a linear percentage. In other words, it can't take 20 hp to turn at 10 mph, but 200 to turn it at 100 mph, aerodynamics aside. We're talking drivetrain losses only.

The difference in loss from auto to manual, with a locked converter, is negligible. We see very similar numbers with the locked converters compared to clutches. They're a little lower, but not a bunch. Unlocked converters, on the other hand, can absorb anywhere from an additional 10 hp to an additional 50 hp.