Floobydust

Pardon me if this question has already been asked, but I'm somewhat new to the SLK forum. There are several "power enhancement" pulley's available from several different sources. All of them seem to be based on larger crankshaft pulleys or adapter rings for the crankshaft pulley. Changing the crankshaft pulley seems to have several drawbacks: loss of the factory damper, reliability issues (adapter ring), longer drive belt, hard installation, etc. Why doesn't anyone just make the pulley on the supercharger smaller (maybe someone does?)? A 10% reduction in the diameter of this pulley would probably not even require a different drive belt and would probably be much easier to install. Does anyone know?

Thanks,

FD

trench

Depends on the year, for the 2000 model year the design of the supercharger pulley was changed such that it cannot be made smaller. After removal of the clutch system, the "nose" of the supercharger now sticks into the pulley itself, as shown in the attached picture.

The pre-2000 versions of the SLK230 with the supercharger clutch should have a different design which might allow a smaller pulley to be fitted - but I'm not 100% sure that this is indeed the case.

Renntech, ASP, Brabus, Vaeth, and Carlsson crankshaft pulleys all retain the harmonic damper (most are basically factory pulleys with a ring either press-fit or welded onto the factor pulley to increase the diameter. I'd go with a welded version to prevent any potential mishaps.

Cheers, BT

mastermind

The reason most tuners avoid installing as smaller konpressor pulley is pulley belt slippage: the diminuitive size of the pulley offers little "grabbing" surface for the belt anyways, so making it even smaller only increases slippage and boost/power loss. Also, replacing the kompressor pulley is beyond DIY for most, thus reducing mail-in business. Lastly, the pre-2000 models have a clutch to disengage the kompressor completely at rpms <3000, depending on driving conditions. This was done to extend the lifespan of the kompressor, and idle noise. Dynosport racing is a company that used to offer a smaller kompressor pulley, everyone else I know of is using crankshaft pulleys.
With the crankshaft solution it is very important to retain the orginal pulleyvdampeners as severe engine damage (crankshaft bearings and rods) can result from an inappropriate aftermarket pulley. ASP racing offers the welded solution, Carlsson, Väth and Kleeman use heavier screws to ensure pulley longevity. All these retain the OEM pulley by adding a pulley ring in increase diameter. I have a simple screw-on pulley ring which most tuners used then, works just fine since 3+ years.

DickB

mastermind, what other modifications have you made, if any, to accommodate your pulley? MAF relocation, plugs, FPR, ecu?

mastermind

I relocated the MAS on my pre-2000 model which eliminted that 3000 rpm hole. GIAC chip, larger intercooler (Vaeth) and Supersprint header/muffler are the other mods. I also replaced the (narrow) air box intake snorkel with a larger one.

trench

Hey, what's your opinion on the headers, you're the first person I've seen to do this mod. This is usually the first thing I change on any car, but have heard differing opinions on how well it works on the M111 motor, since this is a supercharged engine it isn't as critical. However, with a pulley mod it's got to help.

Cheers, BT

mastermind

Hi trench,

The headers were installed before the intercooler got in.

I didn't notice much after installation of the header, maybe a bit more mid-range grunt but that's of course very subjective. Interestingly, if you can trust the water temp gauge, heat stress was significantly reduced. Before, temp was 85-90, after, it came down to 80 for most driving conditions.

On the other hand, the larger intercooler really helped performance, I guess primarily because of its much larger cross section compared to the OEM part = better air flow to engine. However, the header may now more effectively contribute, too, as more gas leaving the engine needs to be taken care of.

In any event, I hope to find a shop with a dyno soon so I can finally see the hp return on these many investments....

mJstk01

Does anyone know how the Contact number to ASP so I can get a upgraded crankshaft pulley for more boost?? And also what is the cheapest everyone has gotten theirs for?

Thanks in advance...

Driller

Call Lee @ ASP Racing....for his #, check out their web site is:

http://www.aspracing.com/frame.htm

Floobydust

I see the issues now - a really picture is worth a thousand words! Thank you all for your comments.

- FD

trench

The reduction in water temp makes sense, the header will enhance exhaust flow out of the engine, getting that hot gas away from the motor more efficiently should make it run slightly cooler.

Yeah, usually the combination of mods enhances the performace of the other mods. This is why I've always thought of adding mods in terms of percentages. Instead of saying, "That mod adds 20 hp." I've always perfered to think more along the lines of, "That mod adds 10% more power."

So headers that give 5% more power alone, will still give 5% more power with a pulley. But you've started, from a higher initial power output with the pulley, so there is a higher overall horsepower increase with headers if there is a pulley there.

Thanks for the header feedback, BT

Pelle75

What about the gearbox can it take the extra increase in HP?
I have an automtic in my SLK 230 komp -01 and I'm thinking of modify it further.

mastermind

I have an automatic transmission which can easily "digest" the added torque, the same model is used right up to the V8s. The manual transmission is a different story: the clutch seems to be "weaker", and you may experience earlier clutch failure with your upgrade. MB improved quality of the clutch for the face-lifted models, though, and I haven't seen complaints since.