Yeah!

With all this talk of how much hp & tq as well as weight being factored into the equation for performance, does anyone know how much of a drivetrain loss there is w/this 8-speed auto tranny? As most of you know, every (if not all) auto trannies have a steeper percentage loss compared to it's manual counterpart for the same vehicle. So with all this talk about it having 425-450 hp & 370-380 tq, I wonder how much of a disadvantage the IS-F will have compared w/the M3 & RS4 motors that have a manual tranny? In otherwords, I wonder how much of a bigger percentage loss it's going to be (at/to the rear wheels) since the IS-F has an auto tranny? And yes, I've searched the LS460 forum (all 5 pages) to see if anyone has dynoed yet (nope).

iSuxeL

iTrader: (21)

If Im correct the new M3 doesnt have manual. BTW do you own Pho Shizzle?? Cause you ordered both the IS-F and M3?? Baller?

05RollaXRS

M3 is available only in manual transmission. Next year a dual-clutch 7 speed sequential manual will be available.

RWD with manual transmission have 15 - 17% drivetrain loss while RWD with automatic transmission (due to lock-up torque converter sapping power) is 20 - 25%."

Here is a great article with a lot of info on transmissions:

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

mr. haison

A little off topic, but will the IS-F come with a true limited slip diff?

Yeah!

When it's available next month in Europe, it'll only be available w/a regular manual. However there are rumors when the North American version is launched next March, the dual clutch automated manual will be available at the sametime. If not then I'll wait for that version to come out then get the M3. It's a love or hate topic w/smg but I loved it when I had an e46 M3.

LOL, no I don't own Pho Shizzle. I saw it online somewhere & I thought it was pretty funny. Supposedly, some pho place is called, "What The Pho" haha! Nah, I'm no balla. Actually, we're trading in my gf's sc430 for the IS-F & I'm getting the M3 for a weekend toy. Although she's starting to get cold feet since she doesn't really need a v8 w/400+ hp.

I just talked to the salesguy earlier today & he told me it's officially called DMG now. I don't know if he was pulling my leg about that name but at least it has a name now.

Not that I'm aware of but somebody correct me if I'm wrong.

lobuxracer

iTrader: (2)

Supras lose 15% with manuals and 18% with autos. I have no idea where you came up with 20 - 25% for anything less than 4WD.

I read the article. This is not my experience (and the experience of many others) with Supras using the Getrag 233 and the A760E from direct dyno measurements.

CK6Speed

iTrader: (1)

20% is pretty typical. For example. My old 250HP automatic SC400 puts down 190-195 to the wheels. That is a little over 20%. My old automatic 230 HP Acura Legend typically puts down about 185 HP. Since it is FWD that is a tad less then 20% but still right around that mark. My NSX 270HP NSX manual put down 240HP. That is about 11%, however, it is a mid engine so no drive shaft.

Anyway, I think even automatic trannies today are getting a little more efficient. I probably would guess somewhere between that 18% you mentioned and 20%.

lobuxracer

iTrader: (2)

As another example, we're seeing IS350s dyno between 257 and 263 on the amazing Dynojet. They're rated at 306 hp. Assuming they make at least this number, we get ~14% - 16% loss through the drivetrain. If we had a 20% loss, it would take 328 hp to arrive at 263 measured at the rear wheel. While it would be wonderful to believe this could be possible, I seriously doubt the engines are making considerably more than 306.

If we were actually losing 20%, we'd see numbers in the 245 range as typical dyno results.

vip3r1850

Forget drivetrain losss . . . it doesnt mean anything.

Im the founder of a mustang club here in NY and we had 2 v6's battle it out (both stock), one had an auto with a simple tranny tune to increase line pressure vs. the old t5 manual that came in the 99-04 mustangs and the auto was always ahead of the manual tranny loss or not so its not a concern of mine. Unless your mario you wont outshift an automatic especially if were talking about high horsepower cars like this . . . Just my .02

lobuxracer

iTrader: (2)

Very true for drag racing. Not so true for circuit racing. Slushbox losses were just one of the very large problems automatics faced in circuit racing when Jim Hall's Chaparrals were using them for the first time.

flipside909

No it will not. But yes it does leave two healthy tire tread tracks during the numerous burnouts at Laguna Seca last week. One sided burnouts are non existent.

ES3

How much more do you think a LSD would improve handling?

05RollaXRS

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

I had posted one example article that states autos to be losing 20 - 25% through the drivetrain (link above). This is one of the many I have read and found consistent information regarding drivetrain loss.

A lot of these articles are old. Recently, this must've changed a bit with the new much more strict SAE standards where the drivetrain loss have been reduced as the crank HP rating is done after power steering, pumps etc. are installed.

From all the videos of IS350 I checked of stock dynos (including one from official Fujita F5 intake video of before and after, where it dynoed ~ 253 WHP and 223 WTQ), the IS350 does dyno between 251 - 256 WHP mostly and over 261 - 263 WHP with an intake (and possibly a bit higher with exhaust on). As you said, that is in the 17 - 18% region.

lobuxracer

iTrader: (2)

The article dances around the real problem and does a wonderful job of explaining why using inertial measurements for power are fundamentally flawed. An engine dynomometer measures the force produced by the engine at a given rpm when a brake is applied sufficient to stop the engine. That's why it's called brake horsepower. It doesn't matter if its eddy current, water, or friction, they all provide a load and measure the force applied to that load, then use RPM to calculate power. One of the other problems is units - kW is a much better way of expressing engine power, but that's another discussion.

A chassis dyno can't do what an engine brake dyno does easily because you have all those driveline devices in the way, and because you are measuring acceleration, you are not really measuring the engine's ability to do work, you're measuring the engine's ability to accelerate a mass, not move a known mass a known distance. Lightweight anything, as suggested in the article, increases horsepower. That's absolute hogwash.

The engine's ability to support a load has nothing to do with the weight of the components, and everything to do with its ability to generate a force (torque) against a resistive force, to produce a measurable result. A 200 hp engine in a 2000 lb car will produce a given top speed based on the car's Cd, tire drag, and basic frictional losses. If we add 2000 lbs to that car without changing the Cd, tire drag (THEORETICAL, not real world), and basic frictional losses the top speed will be identical. The amount of time it takes to get there will be quite a bit longer, but 200 hp pushes against the primary component resisting acceleration (air mass) the same in both cars, so the top speeds will be identical.

Also, identical flywheels of different weights will show up on a dynojet as a change in horsepower without any change to the engine. This is not true horsepower because the top speed of the car will not change even 1 mph as acceleration approaches zero (steady state operation) despite the loss of mass in the flywheel. The lighter flywheel will undoubtedly accelerate faster, but it will not create horsepower, it will just allow the existing power to do the same work more quickly. Conversely, when you let off the gas, it will also slow more quickly - the knife cuts both ways.

So the real test is to measure force at the flywheel and simultaneously measure force at the wheels with strain gauges. Then you can end all the guesses as to how much is lost through friction and fluid drag in the drivetrain. I agree with a fair amount of what he says in terms of more heat being lost, and heat management being key to getting the most out of any system, but his statement about turbos working because the exhaust gases are still expanding for 18" after leaving the port is totally confused and misrepresents the way turbos work completely. If this were true, then true headers would not show hp improvements with turbos, but they always do produce better numbers than short log manifolds. So, part of it is right and good, other parts are IMHO, misguided or misunderstood.

RocketGuy3

iTrader: (1)

So you're saying the lighter flywheel would free up some torque to the wheels, right? If more force is available at the wheels at a given RPM, doesn't that mean more power is also available at that RPM?