Driveline Losses

[walt mckenna]

Last Friday, I took my car to the Ford Nationals in Carlisle PA and took the opportunity to put it up on the chassis dyno to measure rear wheel horsepower and torque. The factory rated the 04 Mach 1 engine at 305 hp and 320 lbft. On the chassis dyno, the engine produced 291 hp and 303
lbft at the wheels. That's a far cry from the old 15% rule. Has anyone measured flywheel and rear wheel hp/torque, with the same engine, to get a true driveline loss using a TKO 600 (or Tremec 3550) with a Mustang 8.8 differential?

[GoDadGo]

Last Friday, I took my car to the Ford Nationals in Carlisle PA and took the opportunity to put it up on the chassis dyno to measure rear wheel horsepower and torque. The factory rated the 04 Mach 1 engine at 305 hp and 320 lbft. On the chassis dyno, the engine produced 291 hp and 303
lbft at the wheels. That's a far cry from the old 15% rule. Has anyone measured flywheel and rear wheel hp/torque, with the same engine, to get a true driveline loss using a TKO 600 (or Tremec 3550) with a Mustang 8.8 differential?

One Thing To Consider, Among Many, Is What Fuel Did You Use To Make The Pull?

If the original numbers were derived using 100% gasoline and you made your pull with the ever so Unpopular 90% Gas 10% Ethanol Fuel, then your power will be down a pretty good bit.

My long in the tooth daily driver loses 10% of it's fuel mileage when running on ethanol enriched fuel. 28-30 MPG @ 70 MPH drops to 24-26 MPG and my oil temperature drops as well because the ethanol laced fuel burns cooler. Next I will also see my 1/4 Mile E.T.'s drop 6-8 tenth on average, dropping from 12:80-13:20 range up to 13:50-13:90's at my Wednesday Night Home Away From Home (since 1978) at a place known as Gulfport Dragway.

Don't fret over the dyno numbers because atmospheric conditions and fuel have pushed my car as low as 12:30's and has high as 14:30's. Since I've had this car for way too long and made way too many passes on it then I can tell you that when Ford Published the numbers every factor was probably perfect when they stated their advertised figures.

My daily is rated at 300 HP @ 330 Lbs Torque:
https://youtu.be/svZX2BMSDEs

Again Don't Fret About The Factory HP Figures Because They Are Used To Sell Cars!

Steve

[DaveS53]

The Ford rating was for a totally stock engine, with catalytic converters and stock (restrictive) exhaust system. You should pick up a little power when installed with no cats and a more free flowing exhaust. Computer tuning can also raise the power level.

The EPA says that E10 should only reduce fuel mileage by about 3% and not reduce power, as long as the engine is tuned for it. A modern fuel injected engine should handle E10 gas better than a carburerated car. A carb may need a jetting change to optimize power and mileage with varying fuels. Same goes for weather conditions and altitude. EFI handles those changes better, too.

E10 is all you can get in many areas. FWIW, my 2014 455 hp Corvette gets 20 mpg in city driving with it and it's only rated at 16. Take a trip with a decent amount of highway driving and it goes up to 26 mpg. The 430 hp LS3 in my '37 hot rod gets the same 20 mpg in town, using E10.

[Jeff Kleiner]

Steve,
What Walt is saying is the opposite...allowing for the generally accepted approximate 15% drivetrain loss he would expect to see LOWER rear wheel numbers. Something on the order of 260/272 (305/320*.85).

Jeff

[NAZ]

Just want to echo what Dad said above. Weather, density altitude, fuel, intake & exhaust configuration, accessories -- all make a significant difference in power output. Even if you ran back to back pulls within minutes of each other and on a different brand dyno you can expect some measuring differences. There are far too many uncontrolled variables between the factory claimed H.P. number and you're chassis dyno run to infer anything about drivetrain losses. It's fun to throw out horsepower numbers derived from a dyno pull but the real value of a dyno is in it's ability to show performance change when tuning or testing parts / modifications. But even that is worthless if environmental variables that affect output are not controlled.

[mach'er]

2003-2004 Mustang Mach 1... I loved those cars. They were monsters. At the Atlanta Fun Ford Weekend in April, 2002, a prototype manual trans car ran in the 12's. The automatic there was in the mid-13's. (see the last few paragraphs here... http://www.mustangandfords.com/news/0208mmff-thunderroad/ Seems like it wasn't that long ago, but only remnants remain of evidence on the web.)

If I was doing a more modern powertrain, a 03/04 Mach 1 M/T engine would have been my choice. I hope you like the engine.

[BEAR-AvHistory]

Dyno should be used for tuning. Get a base line tune or modify & get an improvement over base line or if you screw up a reduction from base line. Typically on the same machine under the same atmospheric conditions.

Too many variables come into play when trying to use it for anything else. Dyno manufacture. Two of the main builders DynoJet & Mustang are the most common chassis dynos. 99% of the horsepower gained vendor adds are based on DynoJet numbers because they will read higher than the Mustang AKA Heartbreaker due to the way they generate the numbers. The Mustang is usually a better tuning tool.

Most all manufacturer advertised numbers are semi-baked by the marketing people to suit the expected audience so that number minus the old standby 15% is not necessarily going to equal wheel horsepower the dyno puts out.

As noted with our car the lower rotational mass, better exhaust system etc would reduce the standard 15% factor. The only way to find out the number is run the engine on an engine dyno then on your choice of chassis dyno & compare the numbers. Of course if you then run it on a competing chassis dyno you will get a different factor.

To get a bragging rights number run it on a DynoJet set to STD Smoothing:5 & hit the number by +10%. But then again if you use SAE Smoothing 5 you will get a lower number.:confused:

[walt mckenna]

Steve,
What Walt is saying is the opposite...allowing for the generally accepted approximate 15% drivetrain loss he would expect to see LOWER rear wheel numbers. Something on the order of 260/272 (305/320*.85).

Jeff

Jeff is right. I expected to see the 260/272 combo and when I didn't, my first thoughts were either the driveline losses are a lot less then 15% or the factory underrated the motor. I thought maybe one of you had dyno'ed your engine alone and then your roadster, with TKO and 8.8, to get true driveline loss. I am very happy with the chassis dyno numbers; just wanted to find the true driveline loss number.

https://www.youtube.com/watch?v=ru2wnoFNLNg

https://www.youtube.com/watch?v=mKhGtrCMoKY

[myjones]

Dyno should be used for tuning. Too many variables come into play when trying to use it for anything else.
As noted with our car the lower rotational mass, better exhaust system etc would reduce the standard 15% factor. :

A couple numbers I got directly from the SRT power train guys at Dodge for the 3G Hemi.
Exhaust manifolds varied the output by 15Hp from the truck to car configuration. Oil pans/windage changed HP drastically from a dry sump/dyno pan to
the typical car pan. The belt turned accessories on the 5.7 pull 41 HP. Look at those three variables and you'll see a lot of possibilities as to why he
pulled more than the expected RWHP numbers. You also have to be careful when looking back at OEM numbers because they used to publish gross HP
numbers and now they list net HP numbers. I don't recall exactly when the ASAE adopted that change but it did happen some time ago. Dyno numers
are good to tune with but just bench racing beyond that use.
DB

[DaveS53]

The change from gross to net horsepower rating happened back in 1972, so it really has no relevance when comparing modern engines.

https://ateupwithmotor.com/terms-technology-definitions/gross-versus-net-horsepower/

There was a minor change to the rating procedure in 2005.

[bobl]

OEM mfgs use the SAE J1349 correction factor, plus pretty stringent controls, so their numbers generally are a bit conservative compared to what you would see on an engine or chassis dyno. Many shops will use the J607 correction factor, referred to as standard correction. It uses different temp and baro references. Hp readings are generally about 4 pecent higher. So, you need to see what the weather data was and correction used on your dyno run to be able to get any kind of real comparison. We would almost always see an engine make more HP on an independent shop dyno than the factory rating. Also, a lot of engine dyno testing is done without accessories, mufflers, etc. Then they get chassis tested and see huge losses. When I run an engine on my dyno, I try to have all accessories, PS, alt, etc working, plus complete exhaust system. Then the numbers are more realistic and the tune will be more representative of what you will need in the car.

[Bobby Doug]

Last Friday, I took my car to the Ford Nationals in Carlisle PA and took the opportunity to put it up on the chassis dyno to measure rear wheel horsepower and torque. The factory rated the 04 Mach 1 engine at 305 hp and 320 lbft. On the chassis dyno, the engine produced 291 hp and 303
lbft at the wheels. That's a far cry from the old 15% rule. Has anyone measured flywheel and rear wheel hp/torque, with the same engine, to get a true driveline loss using a TKO 600 (or Tremec 3550) with a Mustang 8.8 differential?

I own an 03 Mach 1 and it is rated at 305hp and the 04s were rated at 310hp. Ford made no changes with the engine from 03 to 04. The consensus back then was they were really about 320 to 325. With a less restrictive exhaust the actual HP could be slightly higher. So the 291 your engine produced would be close to the 15% rule.

[GoDadGo]

Steve,
What Walt is saying is the opposite...allowing for the generally accepted approximate 15% drivetrain loss he would expect to see LOWER rear wheel numbers. Something on the order of 260/272 (305/320*.85).

Jeff

Jeff,

My point is that HP and Torque figures can and vary greatly depending on all sorts of outside factors.

Steve

[BEAR-AvHistory]

Jeff,

My point is that HP and Torque figures can and vary greatly depending on all sorts of outside factors.

Steve

I had 3 different BMW's with the "same" 3.0 300BHP engine. They were different versions of the 3.0 & all over the place on the dyno. One 320BHP actually tested at 319/321WHP. The car companies pick specific numbers to rate their car for a lot of different reasons. Government, Insurance, Marketplace & so on.

Same engine in two different models one more expensive than the other rate at different RPM to give the expensive car more "power".