MHP

After reviewing the results of some other C63 tunes (Kleeman/Renntech) it appears that at least the Kleeman pull was done in 4th gear (based on the mph on the X-axis, my 5th gear pulls net me over 160mph+). Using 4th is good for another 8-10rw vs the results we get in 5th (1:1).
Do we have any stock or just ECU tuned E or CLS 63s that have tested on a Dyno Jet with SAE correction in 5th for the sake of comparison?

Thanks!

Fr33kn63

I dont have my results in front of me but last time I Dyon'd we found 4th gear to be better too for me. 5th gear didnt Dyno out well. 4th appears to be the better gear. I also thought 4th was the 1:1 gear. I have Renntech ECU tune.

MHP

Thanks for replying. 5th gear in the 7 speeds is 1:1, it's 4th gear in the 5 speeds.
Dyno's are setup to read 1:1 when testing which is why the results become skewed towards the positive when using a higher than 1:1 ratio.

Thanks
Andy

MB_Forever

On stock cars, you'll likely hit the speed limiter before you reach redline in 5th gear

TMC M5

I disagree that using a lower gear will skew the numbers higher than using higher 1:1 gear on a dynojet. When you look at some of the higher numbers on V12TT cars they are all without except done in 4th gear (1:1) than the 3rd gears dynos. I would speculate that yes you are getting torque multiplication with the lower gear, however the dyno reading for hp is basically how fast the roller is being accelerated. The lower gear using a higher numerical gearing is going to be limited in how fast it can spin the roller...while the 1:1 gear will be able to spin it that much faster. I think the torque multipliction skews the torque and max hp to a lower rpm (when comparing a 3rd gear dyno vs a 4th gear dyno for the 5spd cars)...but the hp wouldn't peak higher. Just my take on it.

Tom

MHP

Tom,
Those are contradictory statements. How can you say that a higher numerical gear will yield more torque multiplication, meaning more torque at the rear wheels, then state that it won't be able to spin the rollers up like a taller gear (numerically lower with less torque at the tires)?
You are correct in that a DynoJet reads tq (then calculates HP) based on how quickly your car can accelerate a known mass (drums). You will absolutely spin them faster with more torque multiplication (gearing numerically higher than 1:1) caused by using a lower gear which in turn will yield higher (false) numbers.
I'll dyno in both gears (4th and 5th) to show the difference.

Thanks
Andy

MHP

That I can understand (non P30 C63 anyway) but after tuning there is no excuse.

TMC M5

Re-read what I said...the lower gear (meaning 3rd gear) will have a higher torque multiplication...thus it will be able to accelerate the barrel faster.... however...the speed of the barrel will be limited. Speed does not equal acceleration. The higher gear (4th gear) may not have the acceleration of the lower gear (3rd), but the barrel will attain a higher speed. The speed of the barrel will be faster in 4th gear...thus more peak hp.... the 3rd gear pull will yield more torque which is a measure of acceleration and benefits from torque multiplication. I have looked at literally every V12TT dynojet dyno posted on the internet...most don't have a TQ reading (it is a real pain to pick up the tach signal) but every 4th gear dyno showing hp (stock for stock) is higher in 4th gear than in third gear.

Tom

MHP

I read what you wrote several times, and just did it again. What you're saying doesn't make sense because the DJ reads how quickly (READ: acceleration) your vehicle can spin the known mass. Terminal velocity of the drums doesn't play a roll in calculating HP from tq. If your line of thinking were true, cars like Honda S2000s with 9k redlines would be making insane peak HP.
As I said earlier, I'll do pulls in both gears to show the difference. I actually did it with the stock ECU two weeks ago but never saved the runs from 4th gear--which were 10rw higher than 5th.
As for the MB TT V12s, I bet it wouldn't be hard to get Marko to dyno in both gears next week.

rflow306

Tom the higher hp reading in 4th gear for the tt's could also be due to load. In 4Th gear on the dynojet the engine will have higher load as opposed to third, so in fourth the turbo's are spooling better.

The 55 on the other hand makes very little difference between a 3RD or 4Th gear pulls 1 to 4 rwhp difference, I have tested this on my car on several occasions.

A NA motor like the 63 could be different, it would be nice to see graphs for both gears on the same car. Hopefully MPH will be able to do that.

MHP

Good point reg. the load on the turbos.

MB_Forever

Andy, I compiled a list of 63 dynos in this thread....

https://mbworld.org/forums/w211-amg/261529-63-amg-engine-dynos.html#post3061060

MHP

A great idea and resource to have. Thanks for taking the time to save others time.