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

 

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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

 

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

 

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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:

 

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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!

 

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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:

 

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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!

 

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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.

 

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quick update...

ive found a shop which will do CNC machining on the pulley. dropped it off last week and should get it back in 1weeks time.

they said its no problems doing it. it will be ground down to the brabus s/c pulley specification. and all the brabus s/c pulley is, is an Mercedes modified OEM part.

got all new bearings, seals, gasket maket, locktite for bolts etc all i now i need to get new bolts for the s/c housing and O ring for bolt which you fill oil into then time to assemble the unit and good to put it on the car

 

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update - sprayed the s/c to make it look bit better.... not needed but might as well! to keep it stock looking kept the colour silver. paint is high temp & chemical resistant.

still waiting on pulley to come back from CNC shop and then just need to get new bolts for s/c casing and its time to bolt everything up!

 

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another update..... unit is fully re-assembled now.

all to do is when gasket maker sealant dries is fill it up with s/c up with oil and bolt on the pulley when it comes.

then on the car it goes

 

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another update not that exiting but filled it up with oil. 110ml as per eatons specs.

some pics & explanation of porting. note the exit port and rotors. there is a reason why it is a triangle - to match the rotors. also notice how the exit port (triangle is parallel to the rotor blade).

the reason it has to be exact is while the outlet is "discharging" air the inlet has to be SEALED. if its not it greatly reduces the s/c efficiency. ive taken some pics as you rotate the s/c to see the position of the inlet and outlet ports with the rotor blades to see what i mean....

the stock triangle is quite small and it does not provide exact 120 rotor timing - it is very conservative... why? well it wasnt designed from factory OEM to run higher boost (most stock applications are 5-7psi) and it has to meet strict noise requirements.

 

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yep i replaced the rear bearings... fairly easy to get out.
1) you can use a press to press it out
OR
2) place the s/c case on a WOODEN bench, spray some WD40 lubricant around the bearing and place a socket over the bearing and get a socket extension with a hammer and give it a few whacks it will pop right out!

putting it back in is easy... lubricate the housing lightly with some WD40 spray and use a socket to slowly tap it in...

part number is INA FC 65477. i will PM you an Ebay seller which has these cheap and pre-greased ready to go!

 

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so far s/c is completly done, just still waiting on the pulley from the CNC shop (yer i kno its been a while). hopefuly 1-2weeks time!

 

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ill need to give a call to the shop i sent my pulley off to... still waiting!

should make a decent diff running 14psi/1bar boost. say your at around 240hp now, it will most likely bring to approx 260-270hp. porting the eaton (when running more boost) in most cases yeilds 10% gain, so another 26-27hp to be gained. possibly looking at 286hp-297hp (best case) in total...

should get power to weight ratio close to an SLK32...

SLK32 approx 1460kg/350hp = 4.2
SLK230 mod approx 1380kg/297hp = 4.6

lower numbers are better..... still quite close! even if it yeilds around 270hp it would be a mid to low 13sec car. which is not bad at all!

 

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yes a while since update...... but i have the pulley back! machined down from 93mm to 87mm which is the same as the brabus k1s supercharger pulley...

going to give it a light coat of paint, put the clutch back together this weekend and hopfully the whole lot goes on the car next week for 14psi of fun

 

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its finally on the car and what can i say but WOW... its the same sort of diff when going from stock to ASP crank pulley...

tramp the throttle at a 50-60km/h roll and trac control light flashes....

at part throttle at around 3000rpm its at 10psi!... doesnt sound louder but the s/c whine sounds diff like the supercharged cobras.

more pix to come!

side by side shots for now of my stock s/c vs the ported one with smaller s/c pulley

IT HAMMERS!!!!

 

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ill get the a/f checked soon.....

RENNTech's stage 4 kit (back in the day) for the SLK230 pushed it to 285/290bhp for $23,000... and they used a modified eaton s/c by magnuson running 14psi.

for now more pix and a vid clip of its first start...

 

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i just used gasket goo to make a new gasket... held up fine. also used loctite (blue) on the bolts..

how many cc are the injectors?