SleeperX

Round 2. Took the car back to the dyno shop this weekend in order to get the A/F ratio on the chart. Dynoed at 460.65rwhp. A little better than the 449rwhp. NO MODS WERE DONE TO THE CAR IN THE INTERIM. Suprisingly gained a little over 10hp.

In a few weeks, I will be getting green air filters and thermo wrapping my air intakes. Hopefully that will get me closer to 470rwhp. (we shall see).

Thanks to everyone who commented on my last dyno run. Last week my beast peaked out around 5.2K RPMS. It seems to be pulling all the way up to 5750 RPMS now before leveling out. In my opinion, I think I have a heat problem. Any thoughts?

Last week's dyno...
https://mbworld.org/forums/w211-amg/155468-renntech-stage-4-dyno.html

enzom

Hey, Steve. Looks like the ecu is adjusting in some respects. But your AFR's are off the charts. Not sure why.

Where did you have the car dyno'd?

SleeperX

Sent you a PM

SleeperX

Could my A/F be off the chart because it is reading below 10?

Grumpy666

On your previous dyno run, the HP curves flattened out after 5000 RPM. On the chart above, the curves start to flatten out at about 5300 RPM. However, the A/F chart is giving us a good clue as to what is going on. See how the A/F curves are divirging at 5300 RPM, as they head for the bottom of the chart? If this rich condition were due to programming, the curves wouldn't divirge - they would overlay each other. Heat probably wouldn't cause this much curve divirgence, either. This is due to different airflow conditions, which is probably due to different boost levels. I would say that we're seeing the effects of the bypass valve being utilized on your plots.

Prior to about 4500 RPM, your A/F ratio is a little lean. You may want to get a little fuel added to the fuel maps to bring the ratio closer to 12.5:1 in this range.

You may still have a heat issue. The peak torque for your mods should be higher - probably about 20-30 lb-ft higher. Can you data log during a run?

Please ask the dyno operator to plot RPM on the X-axis in future plots.

SleeperX

Thanks for your comments. Surprisingly enough, the dyno operator did plot RPMs on the X-axis, but I think he must have changed it prior to emailing it to me by accident. I was very focused on the RPMs due to my last dyno and my concerns that my hp was plateauing too early. I will see if I can get a copy of my dyno with RPM on the x-axis on Monday. Thanks again for your comments.

Fikse

just have him email you the runfile (the data file) , and you can do all the graphing with the dynojet software that you can download from their site.... RPM's would help....

SleeperX

Will do. Judging by the graph, I believe 6K rpms is at 160mph on this graph and 5Krpms is at about 140mph..

chiromikey

grumpy,

i'm seeing a trend here in your posts/thoughts and it makes a lot of sense. do you think part of the recalled ecu problem is a remapped control of the bypass valve? if so, shouldn't this be an easy fix for tuners (if they knew this was part of the problem)?

Grumpy666

I think they already know it's part of the problem. But I don't think they know where the code is located to fix it.

eclou

Your AFR is so lean under the torque peak that I would advise not running it at WOT until you get it improved. You will lose a head gasket running it that way, or worse.

SleeperX

Please explain....

Ted Baldwin

...............Has your car undergone the secondary air injection pump recall? If so, then you have your answer. There is a load limit in the ECu's that have undergone the recall. At high boost, the ECU pulls timming and you run very rich to protect the engine. I have been saying this and probably sound like a nag by now.

Ted

eclou

Steve,

supercharged motors are tuned to an AFR no leaner than 12.5:1 under wide open throttle to maintain a margin of safety of preventing detonation. Usually the most likely area on the rpm scale for that to occur would in the vicinity of the peak torque curve. That is usually when the motor will be experiencing the peak cylinder pressures during combustion. Your motor is so incredibly lean there - dangerously lean even for a non-supercharged motor - that I promise you that damage will occur if you keep pushing the motor hard. Such damage would include a blown headgasket, burned valves and pistons, to actually throwing a connecting rod and blowing a hole in the side of the block itself.

Turbo motors also are tuned with the same safety margins in mind, however tuners will purposely calibrate it to run leaner (in the 13.5:1 range) prior to peak torque in order to purposely increase exhaust gas temps and velocity for the sake of helping spool up the turbo.

SleeperX

Pardon my ignorance, but are you saying that I should be running closer to 12.5 A/F in the low RPMS which I believe is now reading around 13.5 to 14?

eclou

Precisely. At idle and at cruising speeds under no load, and AFR of 14:1 would be fine. Under load, it should never be at 14:1. Your mods have increased the airflow of the motor, and the ECU programming is not accommodating this correctly. The other possibility would be that the wideband is not accurate because of calibration or because it is not a pre-cat sample. Remember the catalytic converters will alter the exhaust gas sampling and not give you the "real" condition in the combustion chamber where it counts.

SleeperX

What is wideband? So are you saying that myA/F could actually be running richer than what is displayed because of my catalytic converters. Interesting.. Would my A/F reading be different than an A/F reading for a Kleemann K2 car since the K2 cars do not have their primary catalytic converters and I do?

Grumpy666

But the good news is cats will oxidize some of the unburned fuel, so the actual combustion chamber condition will be a little richer than what is sampled at the tail pipe.

eclou

Yes, it should mean that the real AFR may be not as bad, depending on where they put the wideband oxygen sensor. If it is the tailpipe, it is not very useful. If measuring from the exhaust upstream from the cats (I don't know what your system has) then it is highly accurate. From experiences with multiple blown headgaskets and burned valves, I would seriously ease off the car until you know what is really going on with the AFR, and correct it as needed. These blocks are not exactly cheap or widely available.

SleeperX

Car smelled like gasoline today. Was driving it pretty hard.. Any thoughts? Could it be fuel being dumped out of the tailpipes as illustrated in my dyno..