Benz-O-Rama

HA!

Your stock numbers are the same as my ECU tune number, but we all know how smart it is to compare dyno to dyno. I'd be interested in seeing your AFRs, after tune.


I just do my burnout and race the car in 'dyno mode' now. It was the only real way to heat up those tires back there. Otherwise, the car just kills power and makes you look like a complete jackass.

About the shifting...

You're right, they pop into 4th right before the 1320'. It's annoying, but I'm of the belief that machines are smarter/faster than man, so I haven't tried manual mode trans mode yet. If we didn't suffer from heat soak so easily, I'd mess around more, but after 1 run, these V12TTs really need to cool off.

You can however, goof around with tire height. You can manipulate effective gearing, using a shorter/taller overall diameter. Just make sure your math is right before you go buying stuff, as this can get expensive.

The car also doesn't like a big difference in overall diameter front to back. Keep that in mind.

JHDavis

Yeah I hear you on dyno to dyno, it's the strongest 65 graph I've seen for a stocker so I was happy with it but who knows how it compares on other dynos. I will post graphs as soon as I get them, leaving for dyno in a few hours.

More of the same on looking like a jackass. I tried dyno mode once but didn't notice any diff in shift quality or performance BUT for burning out it makes total sense! Good call.

Yep, that's a huge problem, only being able to make one optimal pass every hour or so limits how quickly you can learn the car. Very annoying. I'm sure colder weather would have helped but what are you going to do.

Are you running a track wheel/DR setup? If so what size please? I've heard these cars were finicky about F/R tire sizing, awesome, another hurdle to overcome, may we have another please?

TMC M5

It seems that the best launch for the V12TT w/DRs is to stomp on the gas off idle. Similarly, the CTS-V gets its best times with stomping the throttle off idle. Apparently, one of the GM tuners discovered that the reason behind this is that if you torque brake the CTS-V, it will actually pull some timing because it is getting confused that the throttle and brakes are being applied at the same time...along with the fact that the vehicle speed is 0 mph. I wonder if MB has a similar torque limiting safety. Given how much torque a V12TT makes torque braking may actually help for cars being run with stock tires. However, with drag radials, you will want all the available torque as traction is not going to be an issue if you can get the tires properly warmed with good track prep.

Tom

JHDavis

Tom,

Thanks for the great info. Another question I have is what is the stock stall converter speed? I wonder if I was overshooting it on launch?
What you say about the electronics getting confused makes sense.

Thanks!

JHDavis

Despite non stop rain today we hit the dyno with the SL65 today to see the improvements made via MHP’s v3 CDT (ECU & TCU Tuning) vs stock with BMC filters, and here are the results. I used the same dyno as when I was stock (with filters then too), same brand of 93 octane (Mobil), 4th gear, and SAE correction factor with smoothing set at 5.



Best pull of 567rwhp/791rwtq SAE


Backed up with 566rwhp/778rwtq SAE


Then 563rwhp/790rwtq SAE


Assuming 20% drivetrain loss that equates to 708HP and 989lb/ft at the crank with just tuning and filters on pump gas. I'm quite pleased and absolutely cannot wait to try a dedicated 100 octane tune now!



Videos:






Picture showing a nice safe Air Fuel Ratio:




Graphs:





MHP v3 CDT vs Stock:




Now the question is what to do next, remove the cats or go with a dedicated race gas tune?