Hi again,
I need help regarding a supercharger issue.
My car is a manual w203 c200 Kompressor MY2002, with the M111 engine producing originally 163ps.

In its standard form the car was working under a boost level of 0,37 bar at full throttle. Near the rev limiter this could go a bit higjer (mainly i think due to flow issues).

One year ago i replaced the crank pulley with a bigger one (230mm) sending the boost to 0.68 (0.73 max at rev limiter ). There was a huge increease in performance (dyno showed 214bhp and 290NM of torque and the car was able of constant 7.0s-7.3s for the 0-60mph and once an impressive 14.8s for 1/4mile) a small decrease in fuel economy and everything worked perfect. 4 months later i put custom headers and last march i put a bigger intercooler as summers in greece are hot.

I noticed something was wrong just before putting on the new intercooler. The scanguage readings showed a drop in pressure. the 0.60 had become 0.55 and from 4000-5000rpm dropped to 0.50, and then it would go up again. Just before the rev limiter the 0.73 became 0.68.

I dynoed the car before the Intercooler install. Hence i was right. 202bhp and 270nm of torque.

We installed the intercooler and thorougly checked for leaks. no sign of them.
We dynoed with the intercooler: 212bhp and 28nm of torque.
With the new intercooler pressure dropped a bit more:the 0.55 became 0.50.
And the hole remains. between 4000-5000 the pressure drops to 0.48 and then it goes up. The gain of the ic was that due to better Intake temperatures the ECU gives timing advance of 17-19 degrees at full throttle while before the IC the figures where 12-13 degrees.

Given that for almost 30.000km the pressure was stable (so this must not be an ecu problem) what could be the problem? I suspect the supercharger bypass valve, but i am not sure. the car cannot drop below 7.9 for the 0-60mph and the 15.8 for the 1/4 mile.
To help those who might want to help me i give the following information:
1. all dyno's at the same dyno, first one april 2009, other two on march 2010, tank filled with the same type of gasoline from the same gas station.

2. i frequently erase the ecu adaptation data. Especially before dynos or after mods to allow the ecu to adapt more easily

3. funny thing: outside temps dropped and the 0.50 became 0.56 again (and drops to 0.49 between 4000-5000.

4. i suspect that the ecu open the bypass valve for some reason (maybe outside temps, or over a certain intake temperature)

5. I also supsect that the bypass valve does not totally close maybe due to normal wear but how can i be sure. Star diagnosis showed no problem at all.

6. use the racelogic driftbox to run my performance tests, the scangauge to monitor obd readings, the carsoft for diagnostic purposes and several obd programs installed in my laptop and cell phone for data logging

7. what is the max pressure that the ecu allows?


Any clues would be much appreciated.

 

I have never done this on an M111. But your dyno results are possibly suspect. We have covered the pitfalls of dyno testing frequently on this forum. It always causes a round of arguments but the truth of the matter is that even multi million dollar Dynos are rotten on repeatability. Even in altitude compensated dyno rooms with controlled everything & most importantly controlled IAT.

There are two absolute basics of dyno testing - 1) Always do a throttle reset prior to testing to ensure you are achieving WOT 2) Monitor IAT for correction purposes or preferably control IAT at a constant. Any float in IAT will mess with output big time.

With a forced induction intercooled engine you seldom know what the real air density is that the engine is seeing.

I don't know your set up so is the new intercooler affecting air flow negatively & thus volumetric efficiency?

You say you saw a drop in charge air pressure prior to fitting the larger intercooler. This makes a few things suspect - wastegate or bypass valve - wear in the supercharger, rotors, bearings, housing (Eaton SC's do wear) - ECU having difficulty keeping up with parameter changes over stock.

Did custom headers change exhaust back pressure appreciably?

Is engine temperature under perfect control?

You have not changed compression ratio have you? Are your rings in good condition?

Are you sure you don't have a blown cylinder head gasket? - usually blows from the rear on M111

Are valves in perfect order - no leaks?

You need the coldest air charge possible.

You might be over advancing timing. Do temperatures rise? What does the advance curve look like?

Can your injectors keep up? What is AF ratio at high/peak RPM - Do you have a map of AF ratio? You can't go anywhere near stoichiometric on these engines.

You obviously first need to track down why you lost boost.

I will try & find max boost pressure for you.

The M111 responds well to mods.

Good luck!

 

well,
First of all the dynos are normal enough. We did monitor the ignition advance the iat and the pressure. The power gain in the after ic dyno test was clearly a result of reduced iat and more timing advance. My mech and i have searched every possible pressure drop and we have one common suspect, the bypass valve. On the other hand i was wondering if the problem is caused by the headers. Having kept the rest of the exhaust oem , apart from an AMG muffler, i thing that the fumes are struggling and that the backpressure may have increased. But could this cause a drop in boost pressure?

 

temeratures, valves and everything else works as charm. No changes to compression ratio, or ecu. Initially, after the pulley, 15months ago, and with no other changes te car was giving a healthy 0,68 bar, 0,73 at therev limiter.
I susprct the bypass valve due to the additional pressure drop between 4000-5000 rpm and then rise again. No reason for that if we are dealing with a general pressure loss through something loose

 

I think you had better change out that bypass valve & check the blower for wear.

My worry with the exhaust is that you have reduced back pressure & increased cylinder scavanging. With valve overlap this can cause a reduction in effective boost pressure. It also tends to push the power up the rev range.

Sorry for break in comms earlier. My ADSL line was playing up.

 

well actually i ve decided the bypass is getting replaced next service.

Along with the max pressure question i have a couple of more if youor someone else knows the answers:
1. how do i check the supercharger for wear
2. my mech says that these superchargers (m45) cannot be refurbished or remanufactured. Is that true? because i have seen many ported M62 in the net and I get tempted
3. I have a spare M62. How difficult is to replace the m45 with the m62?

just returned home from a quick trip. during last 4 days i did 262 miles mainly at highways at speeds of over 160km/h (using the cruise control) about 80 of the miles were done around town. consumption at this pace 20mpg

 

oh one last thing:
you mentioned top end power. even before the headers top power came just before the rev limiter. I even thought of lowering the boost and setting the rev limiter higer to achieve more power but i don trust ecu tweaks on the M111 and i am happy of having the car at about 210bhp without electronic mods

 

Many places refurbish these Eaton blowers. This varies from snout bearing changes & oil change to seals, polishing, porting & coatings (ceramic & others). On this forum knowledge seems to be restricted to bearing replacement & porting. I have no idea what the blueprint measurements are to check for wear in the blower housing & rotors. I don't know the interchangeability between 45 and a 62 - the 62 is really for larger capacity engines. Hopefully someone else can help.

I strongly recommend that you address these questions direct to Eaton - then you have it from the horses mouth.

http://www.eaton.com/EatonCom/Produc...Superchargers/

I would be reluctant to change the rev limit on this engine - it is not happy at very high RPM although happier at 2l rather than 2.3l capacity. It's not well balanced either. If you look at the final changes made to the 2.5 Cosworth/Benz version of this engine they changed bore & stroke for higher RPM & fitted a forged crank & rods. Final race limit was 8000RPM - production 7000RPM

Regarding power delivery X RPM. I would expect peak HP close to or at peak RPM but reducing exhaust backpressure & fitting free flow headers usually reduces torque & hp at low RPM in favour of increases at the rev limit.

 

You won't be happy for long as mods REQUIRE an ECU remap! The loss u detect is due to stock ecu vs modified engine parts/air volume !! Believe me its more "dangerous" keeping the engine running like this than having an ecu remap - which is tested by so many members and proved harmless!

 

Listen to glyn he def knows what he's talking about, prob more then MB

 

This thread is ancient!

 

yeah but ppl searching threads still need to know!!

 

haha greece is on the verge of getting kicked out of the EU union

and your doing mods

 

is this some kind of joke u filthy turkish ******* ?

 

lmao turkish?????

 

shut up then

 

why did u call me turkish?

 

'cause u insulted my homeland

 

lol im italian and my homeland is in the same situation...

i was joking around

 

4given then!

 

Giannisang, The measured airmass value input to the ecu has a direct effect on the boost pressure, and the recirculating flap angle, try a good airmass sensor first