[8cd03gro]

Originally Posted by 69bossnine

Maybe, but... What about all these 117-118 traps for the ZL1?? Car & Driver just retired it's long-term-test CTS-V wagon, and if my memory serves, it trapped at 119mph both when new and at 40K miles.

What is the gearing difference like between these two cars? Does the Camaro need n extra shift vs the v?

I think there will be more than one 11 sec pass this fall by owners. The car is capable. I think at some point you'll see 11.8s out of the z. Hopefully MM&FF does a comparo on a good surface with great conditions. I can see smith getting 11.8s out of the z and 11.4-5s out of the gt500.

[SlingShot]

Originally Posted by MauriSSio

hes not saying drivetrain losses are a static number. It cant be. for example an l99 car dynos 320rwhp. thats a drivetrain loss of 80hp. are you saying if the car had an 80hp engine, it wouldnt be able to move the car at all since the drivetrain will soak it all up???

i DO think the percentage goes down though, but its NOT static.

It is a static number after the gearing and ratios are configured. That's kinda the whole point of gears and ratios and work loads. It's all about the efficiency rating of any mechanism or machine.

And yes if the ratio is 1 to 1 a 80hp efficiency rating machine would take a force greater than 80hp to move. Once again that's where ratios come to play.

[VADER SS L99]

Originally Posted by 69bossnine

Agreed, the dyno numbers are "ballpark"... And while we're at it, so are 1/4 mile times... And it's difficult to reverse-calculate crank-hp #'s when the horsepower starts getting so high, because driveline loss decreases as a percentage as you increase power... The "mysteriously high" rear-wheel dyno #'s aren't mysterious to me whatsoever... There's a point at which it only takes X amount of hp to spin the driveline to the ground, and everything after that is gravy. So your percentage-factor decreases. It's not so much a function of Ford's driveline being amazingly slippery, it's more a function of the engine's power output being so high that spinning everything from the input-shaft back takes a low-percentage of the total output.

The bottom-line, as it pertains to straight-line performance, is that you can't argue-away or alter newtonian-physics to make the ZL1 pull-square with the '13 GT500.

As it pertains to road-course speed, that comparison remains to be seen, and we're all just speculating... Speculating should be done in good cheer and good sportsmanship, and a little jabbing here and there adds flavor as long as it's tongue-in-cheek.

I don't see how that is possible and if it were we would be seeing alot more gains from our mods once we reach that magic point. My car stock is in the 320RWHP range and right now its at the 440RWHP range. At what point do my mods equate to 100%RWHP gains? I think the answer should be never. I don't know the exact drivetrain loss for my car but do believe its around 20% both modded and stock. Some cars just have a more efficient drivetrain so their losses are not as great. I am pretty sure almost any Mustang with a heavy 2 piece driveshaft that switches to a 1 piece carbon fiber driveshaft is going to see a increase in RWHP on the same car same dyno. I don't care if he is making 300RWHP or 1000RWHP. Gearing, wheel/tire weight, trans and rear axle type will also play a huge role on how efficient drivetrain losses will be. I don't know if the percentage in losses will go down or not as HP goes up ( maybe someone with a engineering degree can explain why or why not) but I know for sure that you can't get to x amount of horsepower and after that there is no more % lost.

[tooslow]

Originally Posted by Bob Cosby

Agreed. It WILL happen, though perhaps not till this fall.

This, or at least on a very favorable weather day in an area of the country where median temps are not high and humidity is relatively low.

Is there really anyone who does not believe the ZL1 will hit high 11's on the factory Goodyears? I don't recall very many, if any, people disputing that probability, even the die-hard Mustang guys.

[SVT Murrocket]

Originally Posted by Blueclyde

I hear you but I do not think enough people have been down the track yet with the ZL1. I'm still thinking this car has a very high 11 in it on factory tires with a sea level DA and the right driver.

Maybe it does on it's absolute best run under perfect conditions. But on averege the ZL1 is what it has shown to be, which is a low 12 sec car. There is nothing wrong with that.

[SVT Murrocket]

Originally Posted by Blueclyde

We need to remember how highly variable chassis dynos are. There will be readings all over the map. I find chassis dynos only to be good for baselining a car you plan to modify, assuming you use the same dyno for your post modification test. To put a car on a dyno and then back-calculate flywheel HP is hogwash. No doubt that Ford is getting every one of those 662 HP and the same for Chevrolet and the 580 HP the ZL1 puts out. I struggle when I hear people speculating about flywheel HP based on chassis dyno results. Too much variability to get good relaibale data. Take it for what it is worth. Trust me. I know what I speak of here.

You're correct.

[DJ Red Barron]

Originally Posted by shank0668

Photoshop. I have a Tenth Anniversary Trans am project... its a 79. I want to change the bumpers and put an ls1 in it (original motor gone)

You must make the photoshop pic a realty. That thing looks SWEET!!

[69bossnine]

Originally Posted by VADER SS L99

At what point do my mods equate to 100%RWHP gains?

Never... but the percent/ratio of driveline-loss is increasingly diluted as you add more power...

I don't know how to explain it, I just know that it's a physics thing, exponential math and such...

Imagine a team of horses pulling a big sled... You add a horse, and 100% of the horse's power is not being translated directly into the "work" factor of the physics equation. But it does lessen the load for the other horses and makes the work easier for all. The percentage of horse-power versus the effort it takes to make the sled move is reduced.

[Rock36]

Originally Posted by VADER SS L99

I don't see how that is possible and if it were we would be seeing alot more gains from our mods once we reach that magic point. My car stock is in the 320RWHP range and right now its at the 440RWHP range. At what point do my mods equate to 100%RWHP gains? I think the answer should be never. I don't know the exact drivetrain loss for my car but do believe its around 20% both modded and stock. Some cars just have a more efficient drivetrain so their losses are not as great. I am pretty sure almost any Mustang with a heavy 2 piece driveshaft that switches to a 1 piece carbon fiber driveshaft is going to see a increase in RWHP on the same car same dyno. I don't care if he is making 300RWHP or 1000RWHP. Gearing, wheel/tire weight, trans and rear axle type will also play a huge role on how efficient drivetrain losses will be. I don't know if the percentage in losses will go down or not as HP goes up ( maybe someone with a engineering degree can explain why or why not) but I know for sure that you can't get to x amount of horsepower and after that there is no more % lost.

Lets take your car for a second. It started at 320 rwhp from a stock 400 bhp L99. If you do the math that is about a 20% loss. So to look at it another way, between the engine and the wheels, your drivetrain requires roughly 80 hp of work to spin the transmission, driveshaft, differential, axles, wheels etc. and this also includes losses due to friction.

So now you make 440 rwhp, and using 20% as a factor you might claim to make 550 bhp at the engine now with your mods. But that would mean your drivetrain (which is exactly the same as before) now suddenly requires 110 hp to do the same work it did before to spin the exact same drivetrain. That would imply your drivetrain actually became more inefficient even though the percentage of loss didn't change.

Similarly if you took a stock Mustang and put in a one-piece aluminum driveshaft over the two-piece, you would see some improvement in rwhp, but the engine is still untouched and is not suddenly stronger than before. But someone trying to back calculate engine hp based on a new rwhp number might think the engine is more powerful or underrated.

[MauriSSio]

Originally Posted by Rock36

Lets take your car for a second. It started at 320 rwhp from a stock 400 bhp L99. If you do the math that is about a 20% loss. So to look at it another way, between the engine and the wheels, your drivetrain requires roughly 80 hp of work to spin the transmission, driveshaft, differential, axles, wheels etc. and this also includes losses due to friction.

So now you make 440 rwhp, and using 20% as a factor you might claim to make 550 bhp at the engine now with your mods. But that would mean your drivetrain (which is exactly the same as before) now suddenly requires 110 hp to do the same work it did before to spin the exact same drivetrain. That would imply your drivetrain actually became more inefficient even though the percentage of loss didn't change.

Similarly if you took a stock Mustang and put in a one-piece aluminum driveshaft over the two-piece, you would see some improvement in rwhp, but the engine is still untouched and is not suddenly stronger than before. But someone trying to back calculate engine hp based on a new rwhp number might think the engine is more powerful or underrated.

so you dont think spinning it faster would have any effect on how much power it saps? I think a 500hp car would lose more power than a 400hp car using the same drivetrain, but not the same percentage.

[Rock36]

Originally Posted by MauriSSio

so you dont think spinning it faster would have any effect on how much power it saps? I think a 500hp car would lose more power than a 400hp car using the same drivetrain, but not the same percentage.

Well when we are talking peak horsepower that occurs at a fixed rpm that is independent of how long it took to get to that engine speed/rpm.

Now if peak horsepower shifted from say 5800 rpm to 6300 rpm, then that could incur more losses because now we are talking different/faster engine speeds when comparing before and after peak horsepower ratings.

But that is all the more reason why you can't try to figure out what power an engine is making based on rwhp or dyno results, and try to make any meaningful claims from it.

[PYROLYSIS]

Originally Posted by Fenderaddict2

Gotta bring up something here. Keep reading the Camaro is better looking. More modern, sure, good looking maybe even but better looking? That's subjective. And every G5 Camaro looks the same...pretty much. At least with Mustangs there is a variance in the styling. I'd consider a Camaro, but just one. Whereas I'd have both a '12 and 13 Boss or Shelby. Just saying. But then again I have nearly 20 Fender Stratocasters and other than colour they all pretty much look identical.

I have an Epiphone Zakk Wylde Les Paul for sale. Mint condition if you're interested.

[8cd03gro]

Loss to heat as a percentage of power output decreases as power increases because inertia of the drivetrain and friction remain the same regardless of power output. This does not mean loss is a constant because some forces are variable, but the impact of constant forces become less apparent as power increases. These are just hypothetical and in no way accurate as it leaves out a loooottt of variables, but as an example

Let's say I is the force required to overcome the inertia of the drivetrain, it is a constant. Y is the total power output of the engine and X is the power at the wheels. Just for simplicity we will assume a 12% loss due to variables other than inertia. In this oversimplified example the function of total power output to determine wheel hp would be

X = 0.88Y-I

As Y increases, I remains the same. So, let's say I is 10hp, and Y is 400hp.

X = 0.88(400)-10
X = 342 or 85.5% of crank horsepower.

Now we'll increase crank output, Y, to 500

X = 0.88(500)-10
X = 430 or 86% of crank horsepower.

As power increases, power at the wheels will approach, but never reach, 88% of crank horsepower.


Now, again this is massively oversimplified, but you get the idea. Some of the factors that drain hp are constant and some are variable. As you increase power, the constants have less of an impact as far as percentage loss is concerned.

This is much better explained using calculus, but I figure this would be easier understood for some. Hope it helps.
Any engineers, feel free to correct me. My expertise lies in econometrics, not engineering.

[VADER SS L99]

Originally Posted by Rock36

Lets take your car for a second. It started at 320 rwhp from a stock 400 bhp L99. If you do the math that is about a 20% loss. So to look at it another way, between the engine and the wheels, your drivetrain requires roughly 80 hp of work to spin the transmission, driveshaft, differential, axles, wheels etc. and this also includes losses due to friction.

So now you make 440 rwhp, and using 20% as a factor you might claim to make 550 bhp at the engine now with your mods. But that would mean your drivetrain (which is exactly the same as before) now suddenly requires 110 hp to do the same work it did before to spin the exact same drivetrain. That would imply your drivetrain actually became more inefficient even though the percentage of loss didn't change.

Similarly if you took a stock Mustang and put in a one-piece aluminum driveshaft over the two-piece, you would see some improvement in rwhp, but the engine is still untouched and is not suddenly stronger than before. But someone trying to back calculate engine hp based on a new rwhp number might think the engine is more powerful or underrated.

I would totally agree that it is very hard if not impossible to calculate exact crank horsepower from RWHP once you start modding but I never said that you could.

On my paticular setup I dont know if I'm loosing 110 RWHP but I can tell you for a fact that its alot more than the 80RWHP.

There is no one on here that could make me believe that once you get to X amount of horse power that after that you are not loosing any more through the drivetrain.

I never said the engine HP would go up from a 1 piece carbon fiber vs a 2 piece steel driveshaft I said the drivetrain LOSS would be less thus showing RWHP gains.