Avg. HP loss through Drivetrain?

Chubbz155 · 11-18-2008, 05:13 AM

This may be a dumb question but, I was wondering what the Avg. horsepower loss is through the drive train on a LS1 car (Both A4 and M6)? I am interested to see what the numbers are! Also I am wondering if a Stalled Automatic makes a difference? I used the search option, but didn't see what I was looking for. Thanks in advance for the info!

PREDATOR-Z · 11-18-2008, 05:36 AM

12>15%

99 Black Bird T/A · 11-18-2008, 07:07 AM

The efficiency of the torque converter in a stalled A4 will affect driveline loss. A inefficient converter could eat up an extra 5-10% of power vs an efficient one. Yank talks about this effect on their website in tech talk.

http://www.converter.cc/tech_talk/

My rule of thumb has be 18% loss with the typical A4 and 15% of loss with the typical M6 in an F-body. That might be a little high.

PewterScreaminMach · 11-18-2008, 09:51 AM

15% is about as broad of an estimate as you're gonna get. If you have a stalled or built auto, or a heavy rear or driveshaft and gearing, it may be a little closer to 20% or could possibly be a little less than 15% with a totally stock drivetrain. Keep in mind that the LS1 Fbodies were underrated from the factory.

1989GTA · 11-18-2008, 01:20 PM

Just saw a motor engine dyno'd and then chasis dyno'd. On the engine dyno the motor made 525hp. In the car a 1972 Corvette with a 200-4R it made 423rwhp. Pretty close to a 20% loss in that situation. Non lock up torque converter.

1sicws6 · 11-18-2008, 10:39 PM

so what about a m6 with a ram twin disc clutch and heavy 9 inch rear end

Chubbz155 · 11-19-2008, 02:59 AM

Thanks to all of your information guys!!

Moz · 11-21-2008, 08:38 PM

Quote:

Originally Posted by 1sicws6

so what about a m6 with a ram twin disc clutch and heavy 9 inch rear end

I would also like to know this one?

BAKED · 11-22-2008, 02:26 PM

If what you guys are saying is true then the same drive train will rob more power on a 500 rwhp car than it will on a 300rwhp car......

I don't think there is a "set" percentage, just set amounts of power for certain parts.

Like.....

4L60E robs say....30rwhp with a stock converter
T-56 robs 15rwhp
stock 10 bolt robs 6 rwhp
9" robs 15rwhp
Etc......

Of course I just made up those numbers but you get the idea. I'd love to see someone do a test with a bunch of different combo's and compare. Car Craft done a test with rearends, I think it was a 9", a Dana 60 and a 12 bolt. They were all within a couple of horsepower from what I remember!

Shawn MacAnanny · 11-25-2008, 09:33 AM

So say the car only made 60rwhp? It wouldnt turn the drivetrain? I believe its a percentage of the total hp, not a set ammount.

Ryan L · 11-25-2008, 12:01 PM

It's a percentage, not a fixed number. Friction is a factor.

Robin L · 11-25-2008, 12:50 PM

On our Real Street race car we would see about 12% loss. Since the dyno's load in different ways the numbers are really not important. What is important is MORE. So whether it's on the chassis dyno or the stuska engine dyno we work to make the most power.

Automatic's lose a bunch and are a lot harder to nail down.

Gear ratio makes a difference, as does the tire pressure in the tires. We ran a 9' with micro polished gears and saw a difference.

People get way to wacked out with several things....

Cylinder Head Flow Numbers
Dyno Numbers
Cam Specs
Air Fuel Ratio

It is really about who wins the race

LOL

Robin

allbaugh_04 · 11-25-2008, 03:23 PM

I've heard

a4 = 18%+
m6 = 15%+

Slowhawk · 11-25-2008, 03:41 PM

You can guess all you want since engine dyno's and chassis's dyno's can differ alot. I find it easier just talking RWHP.

ramairws6 · 11-25-2008, 05:22 PM

Broke my 441 in on the engine dyno and then put it in my A4 9" full weight Trans Am and it was right at 20% drivetrain loss on a Dyno Jet Chassis dyno. That might give you a little insight?!

2001 Pewter WS6 · 11-25-2008, 08:58 PM

Quote:

Originally Posted by ramairws6

Broke my 441 in on the engine dyno and then put it in my A4 9" full weight Trans Am and it was right at 20% drivetrain loss on a Dyno Jet Chassis dyno. That might give you a little insight?!

Was that with a locked converter???

BAKED · 11-25-2008, 10:06 PM

Quote:

Originally Posted by Shawn MacAnanny

So say the car only made 60rwhp? It wouldnt turn the drivetrain? I believe its a percentage of the total hp, not a set ammount.

Ok, so you are saying that the same exact drive train will rob MORE power from a motor making 1,000 hp compared to a motor making 500hp? That makes no sense what so ever.

And yes, it takes certain amounts of power to turn different objects such as, transmissions, rear ends, superchargers, etc.

Depending on what parts your drivetrain consists of you could come up with a percentage of loss but it will be completely based on what tranny, and rearend are in that vehicle.

Just to make this crystal clear.... Say you have a Camaro in the garage that has a 10 bolt rear end and a T-56 in it. The stock motor made 300 HP to the wheels. With what you are saying (15% rule), the drive train is robbing you of 45 HP. Now you put a built 408 into the same car with the SAME drivetrain and it makes 500 HP to the wheels. If you use the 15% rule again then that same drivetrain that robbed 45 HP from the stock motor is now robbing 75 HP from the 408.
It just doesn't make sense using one or two set percentages for every possible drive train combination.

Get it?

And Robin, I agree 100%. It seems like on the internet dyno numbers are more important than track times.

Shawn MacAnanny · 11-26-2008, 01:10 AM

Quote:

Originally Posted by BAKED

Ok, so you are saying that the same exact drive train will rob MORE power from a motor making 1,000 hp compared to a motor making 500hp? That makes no sense what so ever.:

Yes that is what i am saying. Every part in your drivetrain has an 'efficiency'. The 9" rear end is less efficient due to the lower pinion and heavier rotating mass. It will rob MORE power the MORE horsepower your engine makes. For instance look at engines that flywheel dyno 1000hp. They only put around 800 or so to the wheels. Its always a percentage loss. Never a set ammount.

Even the engine performance is based on a volumentric efficiency which is a percentage. For instance a gen 1 sbc displaces 350 cu.in. Even with the most advance EFI system that could be run on them it still could never match the LS1 (at 346cu.in) for fuel mileage. It's a more efficient design. It's the same displacement moving the same air in a more efficient way. Efficiency is only ever measured as a percentage. The drivetrain has a negative PERCENTAGE loss of efficiency.

Shawn MacAnanny · 11-26-2008, 01:15 AM

A good website i came across breaking it down in detail

http://www.superstang.com/horsepower.htm#Proof1

BAKED · 11-26-2008, 04:27 PM

I understand what you are saying and partially agree. What I don't agree with is what you are saying about a more powerful engine being robbed of more power from the same drive train as the weaker engine would. I haven't read the link that you posted yet but I don't see how the higher HP engine would be robbed of more power than the weaker engine.

I'm pretty open minded and I'm always looking to learn new things about engines/hot rods, etc.
I'll be the first one to admit that I'm no physicists, I'll check out the link that you posted and see if it makes more sense to me.