This is my opinion and isn't fact. I happen to have a Mechanical Engineering degree, but that doesn't always mean a whole lot.

There isn't a constant percentage of power lost in the drivetrain. There are several factors involved and a blanket statement of 20% no-matter-what with an auto and 15% with a manual is unrealistic. It is possible that you could determine a percentage of horsepower lost, if you had a flywheel number and a rear-wheel number. If anything changes, all bets are off (including engine power output).

Higher horsepower mustangs with C-4's that are making 600 at the wheels aren't losing 120+ HP in the drivetrain. 120 HP is a lot of energy to be dispensed by friction and drag.

You can argue this several different ways, but the only way to determine true loss is by having a flywheel and rearwheel measurement. Otherwise it turns into bench racing. If people insist on putting an exaggerated increase on the rear wheel numbers, let them. The race track is the true equalizer.

 

Exactly what I was thinking, it's all bench racing anyhow. And if you read my post carefully, I wrote 11.2% @ max torque, a static measurment under what is more or less laboratory conditions. I agree that any time this matches up to what YOUR truck does on any given day would be a lot of coincidence, but it's the only controlled measurement possible, and that's definely the figure, I've checked it myself. What A test stand does is use an input torque figure from the drive motor (an electric motor, more exact than an actual engine) and measure against an absorber motor that is pulling against it, simulating the weight and resistence of the rest of the divetrain. So it's not anything like real world, but it is an effective way of measuring relative values. What comes out is 88.8 % of what went in at the max torque reading. We don't care nuthin bout horsepower, torque is the only accurate measurement as far as we're concerned.

G

 

I'm glad you guys brought up the bench racing thing first. This kinda stuff almost gets **** doesn't it? It is what it is and what f'n difference does it make.

 

I just always thought that the L was underrated just like the 1st gen camaro z28s. Rated at 290, made closer to 390 and would rev to 7500rpm in stock trim. Now dont jump on me im a ford guy but i just happen to know that about the z28s and i know that it is a fact.

 

As you covered more later thats at max torque, the value at higher rpm will be greater as friction loads increase.


According to who's calculator? If you're using the typical hp formula based on your trap speed thats flywheel hp, not rearwheel....


This is absolutely NOT an accurate way to check, Super Ford did this several times in their early days of Dynojet testing and its ridiculous that they (the "professionals") didn't know better. Your major losses occur when you're applying power, the more power you try to pass and the more rpm you pull the larger the loss through friction. These losses show up as heat, thats why your tranny gets hot, rearend gets hot, etc... Doing a spindown test with an auto will also not give you any torque converter slip.


And that SS has 450+ ft/lbs or torque also right? Torque makes things move, hp is just another way of quantifying torque. Besides, times don't mean much, trap speed tells power. Ls run about 100-101 stock, SS's run about 107, I hardly see that as equal.


Bingo.

 

Assuming optimal gearing in both cases

 

Anyone know how much loss is on my Simplicity's hydrostatic Drive? The mower boasts a 12HP briggs and straton 4cycle engine, but due to the complexity with the different PTO's and the hydrostatic drive, I don't know what's actually getting to the rear tires... I can say, however, that if I slam it into forward from reverse on pavement it will flip over ontop of me... after a few tries, I managed to ride a wheely on it for 10 feet or so...

You guys need to lighten up... I know you all are knowledgable, but quit bickering...

Since Gregg (Factory_Tech) builds the L's tranny for FORD as his job, I'm going to listen to him... Not like I care... dyno numbers don't mean chit to me... all I care about is what my truck can do right here, right now, on the street...cuz, amazingly enough, that's where I drive it 99% of the time...

Is is 5:00 yet!?!??!

 

Hello everyone,

To give you an idea of what has been seen on the eddy-current dyno at Superchips on stock Lightnings & other F-150's when doing drag down testing for driveline losses...........................

Take a 99 or 00 L actually making it's 360 SAE Net flywheel rating, and we generally see right at 291 hp at the wheels. (try finding a stock one making exactly 360 flywheel, luck helps )

The dragdown tests show driveline losses of 69 hp, 360 flywheel giving 291 rear wheel. Many 99 & 00 L's did not make their full rated power, most averaged in the 260-280 hp range at the wheels.

That example (291 wheel, 360 flywheel) would give us a 19.16% driveline loss in the case of stock 1999 & 2000 Lightnings, just to pick one example we can use solid data on here that should help.

I absolutely agree that driveline losses are *not* a fixed percentage, & glad to hear someone else say that. There are many variables, just one of which is power; when you're making more power, you tend to lose a little bit more hp to the driveline in many situations, though the actual *percentage* of loss may even decrease!

Typically in these late-model F-150's in general, with the 4R70W automatic drivetrain we usually see about 65 hp in driveline losses in stock trim. With the 4R100 automatic drivetrain, we generally see another 4-5 hp in driveline losses over the 4R70W automatics, to give us a 69-70 hp loss to the driveline in 2WD configurations. Again, these numbers are based on stock F-150-platform vehicles, 4.2 V-6's, 4.6 & 5.4 V-8's, in addition to the Lightnings that are the real topic at hand here, but in this we can see a pretty constant 65 hp loss for 4R70W and a pretty constant loss of 69-70 hp for the 4R100's at *stock* power levels. That alone clearly shows us that driveline losses are *not* going to be straight percentage-based numbers.

If we take a newer 2001 & up 4.6 automatic F-150 making 231 hp (newer COP units) SAE Net at the flywheel, that 65 hp loss gives us a 28.138% loss in that vehicle. Take a 260 hp 5.4 with the same transmission, and we see about 195 hp at the wheels in stock trim on a healthy truck, for about a 25% loss. This is compared to the 19.16% loss for the Lightning in our earlier example.

Now of course as power goes way up in these Lightnings, you'll tend to lose a bit more horsewpeor, though you can in many cases see the actual percentage of driveline loss decrease.

This just all goes to show that drag-down testing is really required to give you those numbers, that we cannot rely on straight percentages for driveline losses in terms of being really accurate.

Manual trannies, by the way, the typical Ford 5 speed manuals generally see about 32-35 hp driveline losses at stock power levels, so the automatics do generally show roughly twice as much power loss comapred to manuals, as a loose comparison.

Hope this helps & have fun,

 

Mike, are you stating that the Eddy powered Mustang Dyne produces true rwhp results?

I know at this time it is a better unit for measuring resistance at specific rpm points than the Dynojet, but from my understanding it still isn't good at predicting closer rwhp #'s than a Dynojet, and neither machines for true drivetrain % losses.

Have you ever seen a Lightning dynoed at the flywheel? If not then I do not see how anyone can claim that they do not make their factory #'s.

 

Thanks for the info Mike. I might believe 11.2% for the transmission alone...... maybe...... ; but, not for the whole drivetrain. This is a lost cause. Some people have to have their "Super Tranny" to talk about over a six pack and a toolbox. This is the best Ford could do out of the parts bin for our trucks. It's not a bad unit; but, as far as a performance transmission goes, it's nothing special.

If you check the stock dyno numbers for each vehicle and do a little math you'll find that the torque to weight ratio for the Lightning and the LS1 F-bodies is nearly exactly the same. There's actually a slight edge to the F-Body. Poor traction explains the equal elapsed times. The much larger hp to weight ratio for the LS1 F-Body, the gearing differences, and aerodynamics explains the higher trap speeds.