vraa

So uh.. anyone wonder how much weight we could easily save stripping out a W220?

I'm thinking replace all the seats with race spec.

Remember every mod that we do can't take away from the original essence of the car. Other wise it'd end up a one seater big ol' carbon fiber bullet.

Belmondo

If Treynor should go under the radar than everyone should go under the radar.

sillydriver

Now that one argument has died down, I thought I’d risk starting another.

Several of us (myself included) own Mercedes latest crop of Renntech-tuned V12 monsters; mine being an SL, not an S. I think I’ve seen at least three dyno results posted by different members of mbworld, all of which came to just about 525 HP at the rear wheels.

Those rear wheel results are good, hard, consistent data. However everyone wants to know how much net power their car’s engine produces at the flywheel. Everyone, including the tuners themselves, use the same calculation to estimate this: you take rear wheel horsepower and divide by one minus the percentage of power lost in the driveline. Everyone assumes that for an automatic transmission, driveline losses are around 20% or at least the high teens. If we assume 21% as SL65amg did earlier in this thread, those 525 rear wheel HP convert to 525/0.79 = 665 flywheel HP. Renntech itself claims 625 HP for the stage 3 conversion, implying 1-(525/625) = 16% driveline losses.

As a cross-check on this I noticed a recent post by sarb, who dynoed his SL500 and got 254 HP at the rear wheels with an engine rated at 302HP. Here’s the post:

https://mbworld.org/forums/showthrea...077#post689077

If you take 1-(254/302) you get 16% driveline losses, just like Renntech says. That corroborates the calculation, right? So owners of tuned 600s drive cars making well over 600 HP, right?

I don’t think so.

I think the driveline loss calculation is grounded in an engineering mistake. As long as the torque converter is locked, the driveline loss in a given gear and at a given RPM is a fixed amount of power, not a fixed percentage of the power passing through the driveline. In other words, rather than dividing by one minus the percentage you should subtract the number of horsepower lost in the driveline. Why? Because driveline losses are frictional, either in bearings or from pushing lubricants around. At a given engine RPM these losses are the same regardless of the amount of torque being sent through the driveshafts and gears. Such frictional losses produce a constant opposing torque. Multiply that torque by RPM and divide by 5252 and you arrive at the fixed amount of horsepower lost in the driveline.

In the case of sarb’s dyno test the loss of horsepower is 302-254 = 48 HP. Mercedes may slightly underrate their engines, so if we assume it really produces 5% more or 317 HP, the loss is 63 HP. This loss comes at 5600 RPM, the speed at which the engine produces peak power. That loss translates into 63*5252/5600 = 59 pound-feet of friction-induced opposing torque at the flywheel; or I should say 59 if the engine is 5% underrated and 45 pound-feet if it isn’t.

The driveline in the S/SL/CL 600 is substantially similar to the 500 series cars, so driveline losses should be similar. I think the greatest difference must the design of the torque converter, which must handle much more torque in the 600s at a given level of slip. It probably generates more drag. When the converter is locked, however, there is just a little frictional drag as it spins in its housing, so the loss would be similar. Since I doubt whether lateral bearing loads would be much different in the 500 and 600 transmission, there would also be similar friction in the bearings. Maybe losses would be slightly higher in the 600’s heavier-duty differential.

The friction in the 600’s driveline might actually be less that in the 500’s because the engine hits peak power at lower RPMs. Both frictional torque would be less, and the conversion of that torque to HP would be less. Let’s ignore this and split the difference between the underrated and correctly rated cases above. That yields about 55 HP of driveline loss for the 600s.

So the punch line is that our Renntech 600s are producing (Gasp! Horror!) only about 525+55 = 580
HP at the flywheel.

I think there are three supporting pieces of evidence for this. First, I have read in a number of places that AMG claims the turbochargers used in the stock 600 engine can pump enough air to max out at 580 HP. Interesting coincidence, no?

Secondly, when I did my analysis of magazine test results (motivated by the infamous CD SL600 test) their result fit the curve at about 585 HP. Here is the link to that earlier thread.

https://mbworld.org/forums/showthrea...threadid=60577

Finally, it makes sense that the AMG 65 cars with their larger turbocharger compressors would produce more horsepower.

I have no axe to grind here: I would love it if my 600 actually produced over 600 HP. I just don’t think that it does. Now assertions like mine should be tested empirically, so here is my prediction: when the first recipients of AMG 65-engined cars dyno their 604 HP (SAE) machines they will see at least 550 HP at the rear wheels, corroborating the low percentage driveline loss I am arguing for.

absent

BIG BRAVO!!!!!!!!!
This is one of the most intelligent ,sensible posts I have ever seen!
What you are saying really makes sense.
Thanks...

IluvS500

wow i am gonna have to wait until i get my new reading glasses to read that post, my eyes kept loosing focus on that one

treynor

Sillydriver - while your hypothesis is tempting, I'm afraid it is wrong. The force of friction between two surfaces is equal to the coefficient of friction multiplied by the normal force between them, or F=kN. Thus as the force being applied in the driveline increases, so does the friction - and the driveline losses.

FWIW, I believe the major driveline losses are actually in the gear interfaces rather than in the bearings or fluid friction losses. The normal force between the gears is far greater than elsewhere in the system.

IluvS500

damn your smart

sillydriver

Treynor, yes, friction is proportional to the normal force between surfaces. I said “I doubt whether lateral bearing loads would be much different” exactly because it is the lateral load perpendicular to an axel and normal to a bearing surface that produces friction in a bearing. And I also agree that there is a great deal of normal force (and hence frictional force) between the teeth in a set of gears. However, there is very little slippage between the teeth as they interlock and come apart. Therefore there is not much power dissipation, since power is force times distance: in this case the distance over which slippage between teeth occurs.

So I respectfully disagree: my opinion at this point is that the majority of losses are due to processes that are not proportional to torque, at least as long as the torque converter is locked.

What we really need here is an engineer from Daimler Chrysler (or alternatively Borg Warner or the like) to tell us the truth of the matter, since I’m sure they know exactly. In fact I will send an email to the DC help line asking just that.

treynor

SD - interesting, I agree that we both have valid hypothesis. Where's a darn expert when you need one?

CHATMANR

...loving the drama here in the W220 forum...it's pretty boring in the W203.

Well, I have a C320. Couldn't afford a C32 on a sailors paycheck, and getting in on the home buying frenzy here in SoCal seemed to be the best way to spend my money. One day , after retirement; I hope to buy a used S600 and "Renntech" the hell out of it! But until then, I'll drool unabashedly at every S600 I see on the road.

ps: 0-140 in 1.9 sec. will still be the best rush I've ever had!!!


At sea aboard USS John C. Stennis, Jan. 12, 2002 — An F-14 Tomcat from the "Checkmates" of Fighter Squadron Two One One (VF-211) ignites its afterburner seconds before a launch from the number three catapult aboard USS John C. Stennis (CVN 74). The afterburner provides additional thrust during the crucial moments of launch.

e55 baller

0-60 in 3.3 in entirely reasonable....this car has 800+ ft/lb (delivery is at 1800 rpms) of torque and like 670tq to the wheels! If it doesn't spin the transfer can easily result in a 3.3 0-60mph.

With my 1.85 time in my E55 I am sure I am capable of a 3.9 0-60...much less than the claimed 4.5 sec. My AWD S4 has run a best of 1.68 and would run neck and neck with Treynors S600 to about 40 mph....then he would pull 10 cars or 1 second on me thru the 1/4.

Also cartek Z06s are trapping 10.6@130 N/A engine with just 500 rwhp and 500 rwtq. It weighs 1200 less than the S600 and has like 25 less hp and 170 less tq and they run SUB 3-sec 0-60s.

The 427 C5TT Lingenfelter ran a 8.9@153 and a 1.9 0-60 time.

Another crazy but not so crazy idea? Who would win to 60 feet a world class sprinter or an E55 AMG with an average driver?

A world class sprinter can run the 60-foot time in 1.9-2.0 sec (half the 40-yd dash ...record is like 3.85 sec)....as fast as a stock W211 E55 AMG. The sprinter reaches his top 25 mph speed in like 5 steps. At the 60 foot mark the E55 runs him over though

davepl

It's all just bench racing until someone measures it with some accurate method.

Doesn't treynor have the track video somewhere? You could count video frames until the speedometer hits 60 and then divide by 30. You're at the mercy of how accurately you pick the launch frame, though.

Iron Sheik

WOW!!!!!
I thought my 4.4 sec in the 40 yard sprint was good
I need to start training more lol

But 3.85 is just UNREAL!!!!!!!!!!!!!

Iron Sheik

davepl

Great googly mooglies, people. This thread has the worst butchering of math I've seen in years.

By the logic of this thread, I can take the -fact- that my Vette exits the quarter at 120mph, and claim the average speed is thus 60mph, which is one mile per minute, or a quarter mile in a quarter minute.

A quarter minute is 15 seconds, so by this thread's math, my Vette must run a 15.0@120.

Well folks, it doesn't, it runs low 11s.

Acceleration throughout the quarter mile is NOT linear, people.

Thericker

flipflap

Either you could do this, or you could tape it again and hold a watch in front of the camera to. Then see what it shows at launch (get that right!!! ) and then what it shows at 60.... I think that would perhaps work

treynor

I *did* frame-counting on the original video I took inside the car, which is how I measured 3.3 seconds. All the rest of the math, discussion etc. has been supporting that basic measurement.

flipflap

Ok, I think that shold be precise Dont know how exact the clockfrequency generator in the camera is, but i guess there are factors that are more inprecise

Nice car btw! Hope to join that club someday

highdeserthiker

I agree with you 100%. a lot of the posts put up on these boards are by dreamers and fools.

davepl

My Renntech CL600 ran 118mpg in the quarter... someone should be able to back that out to a real horsepower number (though I would not trust the various web calculators to do it) given the weight of a fully loaded CL600 + 220lb driver plus 100lb of fuel.

Then again, performance-based hp calcs would really measure power at the rear wheels, not the flywheel, so scratch that!

Does an F-14 carrier launch -really- go 0-140 that quickly? It's funny you mention it, because my neighbour, who used to fly F-14s off a carrier, while riding in my CL600, said something to the effect of "it's fast, but not as fast as the F-14 launching off a steam catapult" :-)

vraa

What an old post

You guys also forget that those supercars are geared very differently than street cars such as the S600. The S600 doesn't need to go to 200mph (although I bet it could).

treynor

Egads - thread resurrection!

I stand by my statement that the S600 ran 0-60 in 3.3. I've got both videotape and mathmatical evidence that it did. The argument that supercars don't run this kind of acceleration ignore that said supercars are traction limited AND typically don't have torque converter trannys, both of which will make them accelerate more slowly at low speeds (<40 mph) than the HP numbers would indicate.

Consider, as another data point, that the new 997 turbo runs 0-60 in 3.4 secs with an automatic. The Porsche is a 3800lb race weight, 480HP car with an auto and no traction issues -- while the S600 on drag radials is a 4800lb, 620HP car with the same properties. The porsche has 7.9 lbs/HP, the S600 has 7.7 lbs/HP. No surprise, the S600 is slightly faster.

DoctorV8

Interesting info, Ben, and very timely, since I picked up an S600 this weekend. So you are saying that with the drag radials your Rennteched S600 did not trigger ESP during the 0-60 run? Amazing.

1phd1jd

I have the 2004 S600 and a stock dyno test depicted 586 Hp and 675 Tq.

I have driven and owned many cars but the S600 is very, very fast.

My friend has the new C6 Z06 and when we raced, he was three car lengths behind me until I let off of the gas at 80MPH. I believe that the Z06 C6 would have caught up to me once I hit 150MPH.

I also have the 2005 Turbo S 911 Porsche and it have the 600HP/ 600Tq upgrade kit. The S600 would also beat the Porsche since the Porsche has to be shifted and the S600 rocket is press the gas and GO.

Therefore, I do believe that the S600 can achieve these fast ¼ mile times. That is why I have one and will always have an S600 in the garage.

SIMPLY AWESOME

DoctorV8

Is your S600 stock? If so, the Z06 should have an easy time beating it, assuming of course a skilled driver and reasonable traction, though no doubt a Rennteched/ drag radial equipped car may be able to get quite a jump on the traction limited Z06. I haven't been able to get better than a 2.0 sixty foot in my Z, and obviously Ben and others are several 10ths quicker in their Benzes.

Driving both cars back to back is an interesting contrast, for sure. My Z06 traps at 130 mph, though, so I'd love to see how long it would take me to catch a hard launching benz.