Can the bypass hole on the intercooler be blocked or welded up or some thing. To give you all the boost. I heard you lose about 2psi down low in the rev's coz of the bypass.

 

Yes...back in the ol' days Evotech had a certain Bottom Mount intercooler which has bigger IC's and eliminated the Bypass valve...

 

+1

Most modern ECU software tunes modify the opening of the valve but to truly get rid of it, you need to get the DTM intercooler.

HOWEVER, you gotta have the software to boot or car goes limp.

I spent the 5K for the intercooler, than the tuner turned out to be a dirtbag and went belly up.

Still sits on my shelf.

 

when the intercooler bypass lets the boost out where does the air go

 

I don't think the boost escapes, it produces supposedly more torque and power
It has no where to dump it...make a search there are various discussions on this.

 

The bypass valve works when the supercharger is not engaged and the engine is under vacuum.

You lose between 1 and 2psi at high RPM due to belt slippage and that is normal

 

Who was the tuner, if you dont mind me asking....

 

The BP valve is used for two reasons... Torque control and Fuel economy.

The transmission detects toque and tells the Mill computer to back off via the bypass valve which directly affects torque. The torque limit coding is stored in both the Engine & Trans controllers and having it removed requires both computers to be reprogramed together, unfortunately an expensive procedure.

Via DAS my stock torque limit measured 600nm. My mates stock SL55 limit measured around 900nm. Mine now measures over 1200nm after the torque removal process but please bare in mind that the trans has been reworked in respect to strength including the converter. Having the toque limit removed totally from a stock car would stress the Tranz & Diff and/or blow at least one of these as I have learned the hard way.

While idling and low rev's the clutch and bypass valve work together as the charger consumes excessive fuel at the idle state and low RPM cruising. Basically it helps save fuel if you just take it easy and cruse.

So do we actually lose power because of these economy systems? Yes and No...

Yes, if you haven't had the toque limiter set to a higher threshold as only a certain amount of ft-lb's or Nm's will be abel to pass.

No, if you have had the torque limit removed or threshold increased.

I have had the torque limit completely removed from mine, so to check that it's working correctly I did the following.

Hooked up the DAS unit and selected some live data parameters, Toque, RPM, Bypass position and Psi. Then went for a test drive with someone else monitoring the live data.

After a few runs we found that the bypass valve remained fully shut during full throttle through 1st to 3rd gears we didn't go any further as the passenger who was monitoring the DAS had some concentration problems by 3rd.

It was also noted that another digital psi gauge independent of DAS also showed 18psi after the stock cooler with no belt slippage occurring as the wrap kit was installed. The main pulley is a 175mm job.

Did the same tests on a stock 55 and a stock SL55. Both showed the valves opening under full throttle at various positions on both cars thus limiting toque.

The same system is also used on the SLR obviously not affecting power...

Why was the bypass omitted from the DTM cars? I guess that fuel economy and toque management wasn't a concern...

My 2 cents...

 

I love when Finny posts.

Thanks for sharing your incredible knowledge.

 

Excellent description finny...where have you been bro!, lol...

 

FInny - not only one of the most informative and generous contributors to this forum, but also quite the comic! Got a real chuckle from that!

As always Finny - thanks from all of us for sharing your knowledge - this is really what makes the forum interesting for me.

 

It was ole Adam at Euroelites. When the guys with this mod starting toasting pistons, and other customers had nightmare experiences with just tuning, he went belly up.

Some guys still really liked the guy (his tuning. He WAS a nice guy, just picked the wrong tuner to help him) and you may see some of his fans chime in.

 

How can you tell if your belt is slipping?

 

hhmm like the belt edges getting frized
belt hitting stuff around your engine bay
belt jumping onto outer groves and edges of pulleis on the car

just a few examples

 

Also... Check the dyno graph. Jagged peeks in the upper RPM range is a good visual indicator. Flat torque spots in the upper range at full throttle is another giveaway.

 

Finny,

when you say your "raised your ECU's torque limit"----did you do that with STAR?? or did you mean a complete re-map?

Also---after the belt wrap---does your boost hold until redline? My boost is falling of 3-4psi---trying to see if its ECU related(torque limiter). No use adding a belt wrap if the ecu+bypass valve are gonna bungle up your boost anyway.

 

I am almost always wrong. Let's see if I can keep batting 1000

Torque limit raised...I think is a TCU issue which removes the torque limits of the tranny.

Finny?

 

 

Holy Sheet! I GOT ONE!! I GOT ONE!!

Today...today. I consider myself....self. The luckiest man....man....

 

I’m also curious as to what causes the phenomena, even with a “tune.”
From another HYEPWR post…


photo credit Marcus Frost

 

Looks like with that "Tune" they just lowered the load tables in the ECU

 

Was talking with a tuner last year that was trying to come up with a slotted blower pulley setup.

Can you imagine our cars with near zero slip????

Clutches would be burning up weekly, but ohhhhh the fun!!

 

I guess that is a reason why people have said anything above 6200RPM on the 55K cars is a waste...unless tracking the car.

 

That dip in the middle of marcus's graph is probably the ECU/bypass valve. A supercharger is a mechanical device---the only way to vary boost like that is opening the bypass valve.

My problem is with the graph is the falling off at the higher rpm....
1-is that slip??
2-Or is it the natural limit of the supercharger itself??
3-is it ecu/bypass problem??


1-It cant be slip becuase its too smooth. Belt don't slip nice like that. We would see boost spiking and diping if it was slip....

2-If it were the "limits" of the stock SC breathing ability...Wouldnt the sc run out of steam much faster once you put a pulley on. The fallin off of boost would be much steeper i would imagine. But Marcus's graph is like an identical trace...only higher. Like E55Pilot alluded....it looks like the load levels were just moved. The ECU seems to be the culprit.

 

Great discussion. As always, thank you Finny for your insight. It's great to have someone on here who not only deals with the issues we all face, but actually takes the time to figure out what's actually causing them. Part of the problem I have when trying to address any particular issue with these cars is that when you run into something that's not necessarily common knowledge, there's always that learning curve to figuring out what it actually is. This is really an issue of particular interest that would be great to find a solution to.

The graph pictured is my before/after my VRP pulley. It clearly shows the VRP pulley has overdriven the supercharger pulley and therefore increased boost, however we still have this dip in PSI as RPMs increase. This is not a result of belt slippage, because if you were to look at my power graphs, the curves are smooth. In my opinion it is also impossible for a supercharger in our application to be mechanically responsible for the EXACT same drop in boost at two different boost settings. It is obviously a result of the ECU opening some kind of bypass or limiting boost in some other way. We can clearly see that we are losing 2.5psi from peak to redline and this is NOT because the supercharger is inefficient or we are running out of CFM, it is because of some ECU-mandated restriction. It looks to me like it's a nice smooth progressive bleeding and that fashion would correspond with the action of some sort of bleeding valve.

I would further speculate that this "mirrored" boost curve is either the result of TQ limitations being moved up in a unilateral fashion with VRP ECU, but not enough (and I must admit, I don't place much weight in that theory), or that this bypass valve is something that is triggered on an RPM scale, rather than by a load/boost parameter. Finny has indicated he knows the parameters for the bypass valve and has been able to remove them - I would like to hear if he plans on offering bypass removal service for us grateful and eager yanks

-m