stock for comparision... & pic of another ported s/c for comparison

 

Good work Subby.

Can't wait to see the results.

 

so when will you start doing this on the slk32 s/c?

 

been a while...... but here it is so far

inlet & outlet all done. then time to "clean up" the external casing by sand blasting it to get it looking back to its prime!

then rebuild the unit with new bearings and seals... need to find a machine shop here which can grind down my spare s/c pulley down or create me a new pulley. then its a matter of bolting it on for 1 bar / 14psi of boost

 

another quick pic of a stock outlet port vs ported one... still some polishing finishing touches required :thumbsup:

 

Looks really good. I can't wait to see the final results and how the car performs.

 

This is tempting to do to my old one... lol

 

subby, beautiful work, wish i had a second SC i could play with but unfortunatly i dont... Im currently working on building a new rear end and got some tuning tricks up my sleave but what you said cought my eye, you plan on grinding the stock pulley down 7 mm?

If you are secuessfull ill be at my mechine shop next day! the boost you plan on running sounds like alot of fun and the gains im sure will be close to 90HP! (on the theory that 3 PSI with ASP pulley = 40 HP gain). Please keep us informed as to what you are doing because this mod seams like a good bang for you buck (ASP $1200=40 HP vs Subby >$200 90HP)... Good luck and keep up the great work!

 

I like that, should give it significant boost for sure...

 

You're the man Subby!

So when will you be starting your company then? Send a ported SC for $600, $300 core charge

 

thanks!

of course will keep you posted... next few weeks ill hunt down a machine shop in the area that can modify the stock pulley. stock s/c pulley is 94mm. the lowest you can go is 87mm before you have to delete the magnetic clutch. and run into issues with belt slipping etc. the smaller you go the less area there is for the belt to grip. 87 is the lowest and no need to change belt etc. the tensioner will take the slack no probs.

stock charger RPM:

(185mm crank pulley / 94mm sc pulley) x 5800rpm redline (auto)
= 11,414 RPM

ASP pulley RPM
(218mm crank pulley / 94mm sc pulley) x 5800rpm redline (auto)
= 13,451 RPM

doing s/c pulley ONLY RPM
(185mm crank pulley / 87mm sc pulley) x 5800rpm redline (auto)
= 12,333 RPM

ASP pulley RPM + smaller s/c pulley
(218mm crank pulley / 87mm sc pulley) x 5800rpm redline (auto)
= 14,533 RPM

of course PSI depends on other factors done to the engine but those are the RPMs the charger will spin... :thumbsup:

 

pics of the stock pulley in case people wonder what it looks like front back etc.... its pretty easy to get off. it is not pressed on like the eaton m45 on the pre 2000 SLK. a 8mm or was it 10mm bolt holds on the friction plate on the front. easy to take off... carefull taking it off as behind the bolt there are 3 little washers!

the pulley then just slides out pretty easy to remove... the electro magnetic coil sits in the cavity behind the clutch and when electricity goes thru the coiled wires it creates a magnetic field which causes the friction plate to bite the pulley and bam now the s/c spins!

 

Really nice looking work Subby...really nice! I've looked before back when i first bought my car and you are right, there are a lot of what seem to be, intentional blockages and I don't have any idea why they put them in other then structural support. I removed my inlet vanes and removed that piece to dampen the noise and it seems to rev higher and has seemed to move the powerband a little higher in the rev range...I'll be watching your progress!!
Jeff

 

Here is my superchargers.

 

a lot of it to cut costs in manafacturing process (casting) and noise requirements for car manafactures...

a ported s/c can be loud!

ive done a ton on research on porting and there is a reason why the inlet and outlet are the shapes they are. its for a relationship b/w the charge and discharge cycle. they are related. the factory setup doesnt do a 120degree (3 lobe 60degree helix rotors) timing perfectly. when it comes to discharging some of the air goes thru the rotors again being rotated 2-3 times more than it actualy should be = more heat. again this probably doesnt matter in low boost applications and in OE stock manafacture applications but it does matter if more boost is to be run.

comparison of outlet ports (see pic)

eatons m112 on left and eatons tvs on right (peformance s/c)
note the peformance s/c's or any aftermarket s/c dont have silencer holes... (those 2 little slits either side of triangle)

note the rotors blade is exactly parallel to the outlet port... it has to fully seal on the "discharge" cycle of the rotor rotation (exact timing). this is the limitation of porting. you have to port to the rotors line... otherwise you will reduce the units efficiency to pump air :thumbsup:

 

just a chart below showing the s/c efficiency. this is a 4th or 5th gen eaton so the 3rd gen numbers will be worse... porting it will improve this but this is as a guide to show you the efficiency doesn’t dramatically drop off when you spin it harder!

what the hell is a pressure ratio? its simply the amount of boost you wish to run.

ive done 3 lines to compare

1) stock SLK @ ~7psi
2) with ASP crank pulley @ ~10psi
3) with ASP crank pulley + smaller s/c pulley @ ~14psi

ratio is for 7 psi (example) = 7psi + 14.7 (atmosph pressure) / 14.7 = ratio of 1.47!

1) stock psi charger is being running at approx 58% efficiency
2) with ASP pulley its approx 56% efficiency
3) with ASP pulley and smaller s/c pulley its at 52% efficiency

going stock to ASP crank pulley you drop by 3.4%...... going from ASP crank to smaller s/c pulley you drop a further 7.2%... nothing overly major!

roots blowers aint the best..... you see turbo maps and they have figures like 75% (best) and when you push the smaller turbos it comes closer to the 65's-60's

waiting on new bearings & seals from the usa!

 

Subby... you know I push 14psi out the S/C now.. and 10psi in the intake manifold?

 

Stupid question????

Maybe I´m beeing very stupid, but, the question.....

Is there a compatible Eaton TVS to replace our M112??
What would the costd be???
What would the gains in HP be??

Ok, sorry, thats 3 questions....

Best regards

 

Our supercharger is not M112. M112 is a mercedes engine design.

The 1998-2000 supercharger is a M62.
2000+ is M45.

Cost to replace it would be difficult to figure, you have to understand our supercharger is mounted different than most.. and you'd have to find one that has same/similar mounting bolts.

HP gains, asking what that can be is really a difficult question to answer. With enough money any HP you seek is possible.

 

Actually, there is a Eaton M112 supercharger, usually installed with larger V6, V8. The issue is that none of the Mercedes OEM brackets will accomodate that model, completely different in- and outlet dimensions. The nose is also different. One could custom-fabricate those though. The issue might then be space, the M112 is quite a bit longer because of the rotors used, ~ 4cm.
M62 Superchargers

 

Jackpot

WOW, I really hit the jackpot of stupidity with this one, found out the M62 goes for about 3000 USD, so, I believe the tvs, even if it was mountable, would be a large amount of cash for sure.

BTW, Gakz, there is a Eaton with ref M112, not that it makes diference....

Any way, this port job does look very good, and with the effort put in it, I hope the results are every bilt of what is expected.

Best regards.

 

Snake, you can find an M62 for FAR less than 3k. Just might have to be patient and search around, if you still can't find one.. PM and I can get you one for like just around 1400 brand new from Mercedes

 

Gakz, you're pushing 14PSI, with ASP pulley and Intake modification? No smaller SC pulley?

 

By the way, not to sidetrack the thread completely... but you mention "smaller SC pulley". I can't seem to find a DIY, or source for a smaller SC pulley. I've seen this discussed, but how does one go about a smaller SC pulley?

Or is similar in nature to porting the SC. Do you actually have to remove the SC, disassemble, and then fit a smaller SC pulley on? This is what I'm lead to believe from my Forum-fishing so far!

P

 

yeh did those factoring boost at the manifold - yeh i know will be higher at the s/c but the RPM's are correct all just to see ball park figures to see the s/c wont be efficiency wont be dramatically diminished. i mean it drops for the ASP pulley slightly but you dont hear anyone complaining? it makes a massive diff to torque and hp even at the cost of slight efficiency :thumbsup:

M62 for benz's float around a lot... cheap ones come up on ebay from time to time... as long as you find one which moves freely and the rotors are in good condition - you can rebuild the unit yourself

pdubq: yeh i have measured 13psi at the s/c (a long while back) and 11psi at the fuel pressure regulator using only ASP pulley. when most people talk about boost here they talk about the "actual" reading at the manifold. you wont find much on smaller s/c pulley (whilst keeping clutch functionality) has been posted as not many people have done it!

as for another s/c eaton offer a TVS blower (similar size to the m62) which probably could bolt up with a custom bracket BUT the problem is the snout of the blower - its too long for our application. the snout which we have now on the M62 is not done by Eaton - benz manufacture that part (it has its own benz part number)... and that bolts on.