You should contact Wetterauer they know how get HP out of Bypass valve...They do in their last stage 3...Chip, pullies and bypass valves 590 HP !!!

 

I went back and reviewed the old posts about the bypass valve and some of the parts drawings Vadim provided.

I'm wondering if the intent of the bypass valve is to actually improve throttle response and performance during times the SC is not engaged (??). Essentially, air can flow from the TB straight through to the engine when the valve is open ??? And, it provides a modulation (similar to the wastegate actuators on Audi's) to smooth the boost transition. I believe this modulation activity can be clipped by adjusting the specified engine load parameter in Audis.

My guess is that if the bypass valve were closed when the SC is not engaged, the ECU will be forced to engage the SC sooner and at lower RPM's in normal driving. When it is closed and the SC is not engaged the airflow is impeded, forcing the driver to use more throttle to get the car rolling. This would be great news for me, I've been trying (with moderate success) to find ways to get the SC to engage "sooner" and smoother.

Maybe the bypass valve is also a tool we could use to go to a solid pulley and ditch the SC clutch?

If I am even partially on the right track with the above, I can foresee that there are performance improvements that can be gained with the bypass valve. Also, it makes sense to me that the bypass valve activity is independent of boost, if it was intended to purely bleed off boost I would think the guys that add pulleys without ECU updates would not be seeing significant improvements.

 

I sent them an email.. We'll see what they say.. I hope you are right. Thanks for the tip!


I went back and reviewed the old posts about the bypass valve and some of the parts drawings Vadim provided.

I'm wondering if the intent of the bypass valve is to actually improve throttle response and performance during times the SC is not engaged (??). Essentially, air can flow from the TB straight through to the engine when the valve is open ??? And, it provides a modulation (similar to the wastegate actuators on Audi's) to smooth the boost transition. I believe this modulation activity can be clipped by adjusting the specified engine load parameter in Audis.

My guess is that if the bypass valve were closed when the SC is not engaged, the ECU will be forced to engage the SC sooner and at lower RPM's in normal driving. When it is closed and the SC is not engaged the airflow is impeded, forcing the driver to use more throttle to get the car rolling. This would be great news for me, I've been trying (with moderate success) to find ways to get the SC to engage "sooner" and smoother.

You make a very good point... I actually had similar thinking... I know the bypass valve helps with airflow when the SC is disengaged, BUT... Think about this --- What did they do to control airflow on the early 2003 SL55 that I got this 80mm TB from? It had NO bypass valve (as you can see from the photo of the supercharger inlet) on it. I know there is a way to make the car work without the darn bypass because the early model cars were missing it.

Damn.. I wish I had a Euro SL55 around me somewhere that I could partially take apart.. I would love to know how things are wired and put together in the engine bay... It would help greatly...

 

No. I traced a wiring harness that runs from the bypass valve up to the ECU box on the driver's side. The wire is a duplicate of the wire that is on the throttle body and even the pinouts are the same. In fact, the only way to distinguish the 2 cables is that the TB cable has a blue dot/tape to identify it so you don't mix them up.

It is definitely ECU controlled.

 

I think the answer to your question is the airflow on the earlier cars was forced to go through the S/C. MB probably added the bypass valve to make the throttle response more linear, and as a means to bleed boost when needed. If this is the case, a good programmer could compare before/after valve ECUs and see where code has been added.


Wouldn't it be interesting to tap into the line that actuated the stepper motor and monitor voltage levels during all kinds of driving conditions.

If the reflash is now using this valve to limit power, the different perforrmance levels reported by various posters could be something as simple as the closed-position calibration of the valve. Since very little valve opening would be required to bleed a few pounds of boost, just a slight miscalibration could cause a lot to be bled, or almost none, depending on which side of zero the valve is actually sitting. Something to think about.

I could see a control box in your future. Something that sits between the ECU and bypass valve that passes signals during normal operation, but commands the bypass valve closed when the S/C clutch engages. Something else to think about.

 

My theory (and since I've never driven a Euro SL55, it's just a theory :-) ) is that the early Euro SL55's "suffered" from complaints of poor throttle response at idle that turned to hyperactive response once the SC engaged and the intake system got a good flow going. Maybe the 80 mm TB helped alleviate the lack of a bypass valve.

Does it appear that the valve is designed to open without voltage applied or to be closed? I could almost get the courage up to see if my car will not CEL with the bypass valve harness unplugged.

 

You bring up some very good points. I wish I had someone's car that I could take apart to find the answers..

For now, this route cannot be followed without more information.

 

As you know my last action was to order another stock supercharger inlet and have it machined to accept the 80mm AMG TB.. For now, until I find a better way to do it, this is how it will be installed.

I received the part back from the machine shop today. They did a great job on the welds and the machining. They basically attached a 3/8 aluminum plate to the mouth of the SC inlet and bored it out to 80mm to fit perfectly with the TB.

Scheduled to go in on Tuesday for the install... Because the install was Tuesday I decided to get a baseline dyno pull done today.. Numbers are lower than before but are attributed to 3 factors; 1) I have the stock exhaust back on the car now instead of the 3" race exhaust. 2) I am not sure if the recall issues are still plaguing me or not. 3) My A/F is still PIG RICH at the top end so I am not making peak power.

New baseline numbers were 435rwhp, 545rwtq. Right now I am down 37rwhp, 2rwtq. I did this so I can retest on the dyno with the 80mm TB and see what the differences are. Below is a pic of the new supercharger inlet.

 

Grumpy,

Great idea about the control box. Once these current issues are dealt with and my plate is clear this is one of the next issues I want to address.

 

Vrus - is it just an optical illusion or is the inlet housing more restricted (than 80mm) inside ??

 

Would this be roughly after 3000 rpm?...This happened to me as well... Was your fuel economy **** too?

Your pulley is slipping...thats it. After putting extra tension on via the crappy mod I did, the air fuel richness was pushed up the scale to around 4700 rpm after that, rich again... still slipping.

Thats why I need that new tensioner with the added extra one inch foot print.

Any news?

 

By-pass hole...

 

Yup.. Optical illusion.. It is 80mm opening.. They smoothed out the supercharger inlet to port match it to the adapter plate. It is a nice job actually.


Mine is pig rich just after 4,000RPM.. My programmer is probably cursing me cause he keeps telling me the tune is correct but yet my car dives down to below 10:1 after 4,000RPM so I can never make the peak power on the dyno.

I have the new pullies from Evosport. They arrived on Monday but I didnt get a chance to take a pic.. I will snap a pic later and post it here.

 

Same problem.... He is right, the program is fine, Same problem with my tuner as well... I drove him nuts..ha... I eventually conceded that he was correct.

I'm assuming that the above pulleys are already installed with this problem?

 

No. The new pullies are not installed yet.

I inspected them closely a few minutes ago but didnt bother to take pictures.. They are just 3 pullies that wont mean much to you unless you have the Evosport pulley kit.

They supplied me with a new water pump underdrive pulley, a new idler pulley that gets installed between the supercharger and the crankshaft to increase the overall belt length to 52.5". (Gates #K080525), and a new left idler pulley assembly.

This new setup (based on the install pics they sent me) will give better belt wrap.. Vic55 already has this new setup on his car and he is not seeing any slip at all.

I am going to try to have the dealership install these new revised pullies at the same time they do my TB.

I am trying to track down that blue part that you showed in the pic. It is a nice idea to keep the tensioner in place.. Any idea where it comes from or who makes it?

 

So...you have the old set installed and have an upgraded version now... the reason for the upgrade?

Is the idler pulley assembly the wheel only or a revised tensioner & wheel?

Was it sliping before?

Nope... can anyone enlighten us?

Thanks

 

1) I called Evosport asking to purchase a new belt because mine shredded.. Mike right away said he was going to send me new revised pullies because when he went to look at my invoice to see what Part # I needed for the belt replacement he noticed that the revision of pullies I purchased was 1 behind the current. NO COST TO ME, he shipped me a total of 3 new pullies and a new 52.5" belt. Great service from those guys over at Evosport.

2) 1 new water pump pulley, 1 new right idler pulley (it goes between the supercharger pulley and the crank pulley), 1 new tensioner pulley.. On a normal setup, the belt around the supercharger goes right to the crank.. On this setup, there is 1 extra pulley that the belt goes around before it gets to the supercharger. It creates more wrap surface for the belt and lengthens it 1.5" (51" vs 52.5").

3) I am guessing it WAS/IS slipping like crazy because my A/F goes below 10:1 after 4,000RPM.. I know Vic55 had similar issues and with this new setup, it cured the problem for him.

 

My belt was starting to shred about 6 months ago, my car went in for the some other mod and they put on the new pulley and other items. I check it once a week but no issues.

 

Car is at the dealer..

They will *attempt* to get the following installed: 80mm TB, 2006 supercharger clutch pack, revised Evosport pullies. They've got the car for 2 days so it should be enough time to get it complete.

Once this is done, its back to the dyno. Hopefully the new pullies will cure the belt slip issues and I'll be able to get a reading for peak power. Also, we'll be able to test the revised airflow characteristics of the 80mmTB and enlarged supercharger inlet.

It's gonna be a tight week because on Friday, Steve (MBenzNL) will be installing TV Tuner, power trunk closer, and lighted AMG Sills.

 

VRUS, Any chance of some photos when the job is done?

Cheers,

Finny

 

Second for the photos.
I'm always anticipating the next post from vrus, his posts all come together to create an amazing story.

 

 

Sure.. What would you like to see? Mods that Steve is doing or mods in the engine compartment?

Thanks Ricky! You are too kind. Which pics should I take?

Steve,

Thanks! I just hope that after dragging you guys along for this rollercoaster ride with the 80mm TB project that it does what it is supposed to. I've got alot of time & money sunk into this particular project so I really hope that I can show some positive results for everyone when all is said and done.

 

I'm down for any pictures, each one is worth 600 words (40% reduction = tax)

 

I already know what's going to happen... your going to be extremely surprised!

Can't wait...

What's the purpose of the clutch upgrade? Sound or Slip?

Also, a shot of the revised pulley setup would be nice when you get 5.

Cheers...