ams crank pulley and Evosport Underdrive pulley kit
Thats has been installed and my baby is running great. I've checked the pullies often and triple checked for wobble. Originally it looked like there was a tiny tiny bit of wobble on the crank pulley but I think it was more optical. Ryan and I both think it looks true.
The install went easy for the crank pulley.
The install of the evosport pulleys went well with the exception of the water pump pulley. This one didn't fit perfectly but Ryan was able to to make it fit. Ryan mentioned something like it was a minutely off and could use a bit more machining or something. Evosport if you want I'll be happy to give you Ryan's contact info and you can ask him yourself. I don't think this is a issue as it is on fine and working well.
The only thing I can tell so far is that the car seems to pull a bit harder on the mid to high end. I am still letting the car get used to these new pulleys.
I'll see if I can fit some time in to do a dyno next week. BTW would all this damn smoke up here affect a dyno run? Ncal has as ton of wildfires going on.
pedal ecu reset :
1. Turn the ignition key to the on (not start) position.
2. Press the gas pedal to the floor and hold for five seconds.
3. Turn the key to the "off" position (don't remove the key), then release the gas pedal.
4. Wait at least two minutes for ECU to reset.
https://mbworld.org/forums/w211-amg/148019-holy-crap-you-guys-sneaky-ecu-reset-works.html
Last edited by SLK55R; Jun 27, 2008 at 04:45 PM.

Heh heh
I tried to get dyno time today but my original shop was closed and all the other dyno shops, that are open on the weekends, didn't have time.
The Best of Mercedes & AMG
That is officially the cleanest looking pulley I have ever seen
Now butt dyno - I got to be honest I didn't feel that much initially only a little bit extra up top. I have to say now I think the ecu is finally getting used to the pulleys. I think the difference is actually pretty dramatic. I even removed the Xpipe (which should reduce my hp a little) and I think there is a pretty big positive change.
Heh I hope the dyno doesn't call my butt dyno a liar.
Took about 2 hours of labor to install by my independent mechanic, who did a great job. I replaced the belt and nut. The crank seal was fine, so it was not replaced. I decided against the underdrive pulley kit for a number of reasons.
BTW, if anyone needs a good independent Mercedes/BMW mechanic in the South Bay area of Los Angeles, Peter Mardikian of Mardikian Automotive is absolutely fantastic 310-376-4906. He does all my normal service and installs any mods I buy; springs, brakes/rotors, pulley, shocks, alignments, etc. without the annoying questions/comments that usually come from mechanics installing mods. And he is cheap!
The bad news is that there is no good news.
Took the car into the dyno today. Same dyno that i used before ... temp is about 5 degrees hotter today.
These are the changes made since I dyno'd last :
Removed Xpipe
AMS Crank Pulley
Evosport Underdrive Pulleys
2 1/8s longer belt
The difference between my last dyno and today is about -15 RWHP and -6 RWTQ. Their is a loss of hp and torque across the whole pull. Once the car hits around 3500 rpm the difference gets larger and larger. What is more puzzling is that my Air/Fuel Ratio has climbed and I'm running lean. Good thing I run on 100 Octane all the time. No detonation so my current condition isn't dangerous. Previous dynos had my around 10 airfuel ratio at the end ... currently its around 13.
The AMS Crank pulley is the exact same diameter as the stock crank pulley. I will confirm with AMS shortly.
I believe the Evosport pulleys are NOT the same diameter. That is probably why the kit came with a belt. Since all these pulleys are on the same belt ... I think it is throwing things off the supercharger. I will confirm with Evosport that the 3 evosport pulleys are not the same diameter and require a different length belt.
I will be removing the Evosport Pulleys completely tomorrow and redynoing.
I will report numbers again next week.
It may be the Evo sport pulleys interfering w/ SC b/c they are different diameters thereby causing SC to spin at different rate than it normally would. Are you sure belt is not slipping on supercharger pulley due to different diameter accessory pulleys?
Also what were atmospheric conditions, temp alone is not the only factor. Barometric pressure as well as humidity levels also play a factor. any pictures of dynos & A/Fs to help troubleshoot?
Furthermore, b/c AFs are off ECU may be pulling a serious amount of timing to compensate for the lean condition thereby robbing power. All possible scenarios.
Last edited by E55 PWR; Jul 2, 2008 at 09:43 PM.
My thinking is to go back one at a time and see if we can tell. If the results are still negative after the switchback to stock pulleys (evosport removal) then I will switch back to stock crank pulley.
My thinking though is that just an Xpipe can not possibly be at least 15 rwhp. That doesn't make much sense.
Furthermore. In theory since the underdrive kit is smaller diameter, that means the belt is shorter, and since it is shorter that could have some how caused the delicate ratio of supercharger speed to crank speed to have changed. In theory (it is possible) if its shorter that means that the supercharger is spinning faster (more boost), so more air is entering the cylinders thereby causing lean condition and ECU is over compensating via knock sensors and pulling timing or doing God knows whatelse to run as safe as humanly possible, thats the ECU's job. As soon as it senses knock it will immediately do the safest settings possible. You may not hear the detonation or knock itself with the naked ear, but the knock sensors are definitely doing their job (and are fare more sensitive than your ears) and cutting back on power to save the engine (regardless of octane, octane can only do so much, although I'm sure its helping a bit).
Your diagnosis is correct, undo accessory pulley kit, put the original belt back one and see how it performs with just the crank pulley. Then take further action if necessary.
I could be wrong but that is my analysis of the situation, hope that helps.
P.S. you might want to email both companies and get there input as well.
Last edited by E55 PWR; Jul 2, 2008 at 11:56 PM.
One thing that you have wrong is that the belt is LONGER and the underdrive pullies are probably Bigger. I had to use a 2 1/8 inch LONGER belt with the Evosport Pullies than on stock underdrive pullies.
The only reason why it doesn't seem like the ecu is pulling timing is that I would expect it to run rich then. Also if it was really pulling timing I would expect a much larger drop in HP than 15 rwhp.
Btw thanks for your input!
The other reason why I don't think(15 rwhp loss) its from the removal of the xpipe is that when I went from Renntech Shorties to Supersprint Longtubes, Supersprint 100cell cats, and the Supersprint Xpipe, I only picked up around 10 RWHP.
Shouldn't a longer belt mean more boost?
Changing the belt can in theory change the way the SC behaves (either shorter or longer) I have a feeling that is whats making the impact.
Ahh I guess I am wrong in that regards (accessory pulleys), well in that case this may make more sense. If the pulleys are larger and the belt is longer that means per rotation of the crank pulley the SC pulley is spinning less. That would explain why the gap widens as rpms go up b/c the ratio is out of balance. That would mean less boost, hence lower HP. As to why the ECU is running lean... perhaps b/c it senses so much less air the ECU is cutting back fuel hence lean condition. Again this is all speculation, You have to realize that your setup is so rare that probably only a few on planet earth (if anyone else at all) is running your specific setup. Hats off for being brave enough to give it a shot.
Either way it seems the changing of the belt length has had an ill effect on your numbers. Do as you plan, remove accessory pulley kit and diagnose from there.
P.S. when you take off acccessory kit, reset ECU again and allow a few days to adapt again and then redyno to diagnose, that in theory should fix all your problems. I STILL recommend putting X-pipe back and perhaps getting a quieter catback muffler to compensate but again thats your choice.
Last edited by E55 PWR; Jul 3, 2008 at 01:17 AM.
Let us know how it unfolds.
I think you really need to switch over to a Dyno Dynamics Dyno, it is far more accurate for tuning and troubleshooting than the dynojet is. Dynojet isn't going to be able to tell you exactly what happening at the rear wheels which is why I highly recommend you switch over and put it on a dyno dynamics dyno and see what it says.
dynojets are not very accurate, you might as well be using a G-tech. Put it on a DD and it will tell you everything you need to know when doing before & after dynos.
hope that helps









