as in no electric clutch !

There is a company here in Oz that can supply me a Fixed sc pulley and in a 70mm size that would stack nicely with my 178mm crank . They usually make fixed pullies for MB V8s but can make one for the 6.
I have not seen anything on fixed sc pulleys here on the forum , anybody have any experience with them ?

ps , i see EC also make fixed pulleys but only for V8s it seems
see here : http://www.benzboost.com/showthread....cture-and-dyno

 

This has been discussed before here. CLICK
The SC free wheels all the time and the car sits still with the engine running for a small percentage of time when you think about it, Heat generated at idle would be the least amount normally and easily handled by the cooling system.
I think some people might look back on what they said at the time and have second thoughts about what they said.

These have to be very cheap to make, they say CNC machined as if it was a small wonder but that is what is used these days in machine shops, nothing special. The steel would by my estimate be 1/3 of the cost, profit could be quite high if made in decent size batches. without the clutch and its complications these should only cost $200 or so.

 

Thanks 180.
at $200 i would buy one , get an ec retune and just watch the iats carefully ,
the mb v8 guys seem to like them ..alot

The one available here costs over twice that ! ,for alloy , anodised ? is extra.

 

you have to learn to drive your car all over again. because boost is there all the time,
it is like leaving from dead still at wot all the time, you are in boost even at idle, and your relief valve (Computer operated ) no longer opens and closes when told to. when you let off to slow down the boost is still on and the car tries to keep going, when you leave a red light ,your car will buck,jump,until you floor it because of boost. so like i said you have to learn to drive your car all over again,, but try it,you may not like it.
and no the mb and or the v8 crossfire guys don't like them,, out of 10000 v8's ( that are into performance) there are only 10 or so fixed pulley's and at one time there were over 100 ,, there was one on mbworld for sale for $100.00 jim

 

Hi,
good advise. Normally no boost on vacuum (part throttle/idle - closed throttle body). Seems that the electronic throttle pedal doesn`t get the correct information from the ecu and is still open. dangerous. With an old school throttle body (just controlled by wire) it would work for sure.

Steven

Berlin Germany

 

Woody should say if his SC on all the time after initial clutch engagement is true or retract the statement if he found later that it was not true. I have not seen any retraction to date and assume his initial statement is correct.
Calling Woody, are you receiving, over.

 

Where is the release valve ?

 

...Hmmm and I have quoted that as fact to my mechanic....so this may not be true that after initial engagement at 2200rpm its on all the time...ok..and the relief valve statement above...I was unaware that there was one. I do have those symptoms that you describe about the boost building and keeping the RPM's up well after you have released the throttle. I thought only turbo's had the waste gate and thought that our SC 'ers were without any pressure releasing mechanism.
..Please elaborate ...Thank you..

 

yes we have a bypass valve,,When the throttle is opened and the supercharger is called on to produce boost, the bypass valve closes off the re-circulating air thereby forcing all the boosted air into the engine. when let off the throttle the bypass opens. this is on MB World jim

 

Where's Waldo. ...er ... I mean Waldig.

 

Thanks amx1397,
I think i will forget the fixed pulley then , unless there is a tune that makes it run nice, it sounds dangerous ,as is my car is very quick refined and civilised , a bucking jumping srt6 i do Not need.

 

Mercedes turbos yes.
Where is the valve on the SC system? Your so called valve is the clutch.
The SC clutch cuts out, that is why you can hear it winding up when you put your foot down hard, as the clutch engages at that time.
That's the way I see it anyway.

 

this is from the slk32 --170 engine on MB world

The bypass valve on a supercharged motor puts the extra air from the SC back into the airbox when the engine is under low load. This is so that you get good fuel economy, but when you need it, the bypass valve closes so that the air is actually forced into the motor. Its not the same as a BOV on a turbo motor. I dont see any advantage to going to a aftermarket valve. It wont even make a sound, well maybe like a leaking airhose! Although I may be wrong, some one feel free to correct me.
sorry, I'm not so sure about your reply.

I'm still a noob for superchargers, however, I'm a pretty well informed turbo motor user.

The bpv won't open or close solely based on the load of the engine. Stock BPV will hold the compressed air between the supercharger and throttle body. If there's excessive compressed air between supercharger and throttle body, say at 14 psi, you decided to let off the throttle, the bpv will recirculate the unused air between the supercharger and throttle back to the intake tract. The stock bpv won't make any sound because of the recirculation, however, if you install an aftermarket blow off, it will.

On the M271, i see that it's possible with a custom flange and bov base. Some aluminum welding and a plug for the stock recirculate hose will do it. The only draw back is the drive by cable on the MB, on the Subaru, it's possible with either drive by wire or cable.

Also, if you want blow off sound, changing the rubber recirculate hose to a metal pipe will produce that sound. However, the supercharger muffler will kill most of that blow off sound.

All in all, i'm just seeking for the blow off sound, i know fully about the pro's and con's of a bov vs. bpv. i.e. lean/rich , cel codes, rice/not rice, ...etc.

here is more --------------Superchargers have larger and heavier internals than turbochargers

If, when you hit the gas about midway (mid throttle but no boost yet, yet high demand) that inrush of air that you are demanding will not reach the engine instantly because it has to go through the supercharger.

This delay will cause a lag much like turbo lag on throttle input, further, it will decrease fuel effeciency for 2 reasons

1- all the air you're injesting in around town driving would be hot having run through the supercharger
2- you will waist some 10-15 hp of 'milage' always driving the supercharger (and as you know it's not a light thing to drive like a ceramic turbo compressor wheel).

To solve this, supercharges use BYPASS VALVE S (not blow off valves)

a blow off valve vents air on throttle lift to prevent compressor surge.

a bypass valve has 2 functions
1- it vents air on throttle lift to prevent compressor surge
2- it completely BYPASSES the compressor (be it a turbo or a supercharger) on high vacuum / high demand situations to promote throttle response and high effeciency (milage) under off boost driving conditions.

If you took out your stock electronic bypass valve and installed a blow off valve your drivability will suck, your thorttle response will be ****, and your milage will drop significantly as you will technically ALWAYS BE using your supercharger...and very quick into boost (which can hurt traction too)....

the old style bypass valves (like the ones that come on stock mr2 turbos, stock 911 turbos, stock saabs..etc) are vacuum referenced

at high vacuum it will bypass ... this high vacuum is present in 2 situations
1- throttle lift (so it will work as a blow off)
2- high pressure differencial between manifold vacuum and inlet vacuum (ie high demand/high restriction situations where the S/C is 'lagging' or choking the airflow

Newer cars are more fancy using an electronic bypass valve.
With this bypass valve mercedes can do 2 things

1- simulate a mechanical (vacuum referenced) bypass valve
2- limit boost in situations where it wants to (such as traction control for example... the ecu is able to reduce torque output by reducing throttle angle, and opening the bypass valve dropping you out of boost...and then with the aid of selective braking, the ecu is able to re-stabilize the car using ESP)

another nifty feature to this electronic bypass valve is that mercedes if they want to can use it kind of like a wastegate...where they can open it to limit your boost, or limit your 'spool' (how fast the boost builds) even on a roots type supercharger.

 

See the following thread for the SC details. CLICK

 

Wow good info 180.
but it makes wonder how pulley this works:

i know this is for an M113 but isnt the M112 the same minus 2 cyl

https://benzperformanceparts.com.au/...d-pulley-combo

anyhoo i contacted the guy there and he said, yes he can supply a pulley for our 32 and that i would just need EC to adjust the ecu tune .
?? its all very confusing.
I have emailed Eurocharged about it.

 

well onehundred I guess my info may not be correct being that your info is for the crossfire engine, thanks for this info, see i learned something again today. thanks again jim

but my car does have the recirculation valve as
I was going by my V8 (SL55) not the V6 as tunaglove says

 

That came from the " Convertible and Supercharger Engine Update" book.
I have the preceding three pages to those already posted to put up when I scan them.

 

The 113k has the recirculation valve, the 112k engine in the srt6 does not.

 

I'm not a mechanic. But Weistec Engineering Inc. is setting (V-8) world records by bolting down their 3.0 liter twin screw supercharger onto the M113K. Using the Mercedes factory SL55 crank pulley and NO supercharger clutch. Maintaining Mercedes factory original electronic by pass valve with no ill effects. Squirrel Crusher

 

again this is the V 8 correct?