I sort of bought a car that sort of runs. A 1998 SLK230 looks like a good deal at night.

Challenge swag!

In reply to a_florida_man :

Nice!

In reply to Pete Gossett :

Thanks.

At least this part is sure to work.

lol

In reply to FooBag :

The M62 application on my Mercedes is one that has the intake on the end of the case, and the supercharger is mounted on the side of the engine, like an accessory. 

Here is a photo from another car to illustrate.

The small end of the triangle is about 1.5 inches from the ends of the rotors. The porting plan I had proposed was based on porting jobs like these in the MB community.

Before your post, the greatest concern I had was to keep the triangle sides parallel with the angles of the rotor lobes and to maintain the coincident timing of the two lobe to triangle side alignments . Your suggested porting plan would make it such that the triangle edge would no longer align with the lobe line. Do you have an opinion on this? I know very little about supercharger pressure wave dynamics and I'm trying to do more good than harm....    ....trying to. Is the 1.5 inches of rotor lobe that is tucked into the case past the outlet sufficient to prevent air from recycling, thus raising IAT?

Thanks.....

On the m90 i've read taking it out to the silencer ports(those little guys by the V) is bad because you end up with overlap on the intake and exit sides of the rotor and lose boost.  Your plan looks solid.  I've done a lot of eaton research and have an m90 set up to spin 14k so i can try and blow stuff up one of these days.  

In reply to Patrick :

I have the same understanding about distance of the porting from side to side.

Also filling the silencers does not boost pressure or volume, it just makes it louder.

What I haven't seen any info on is the intake pipe....

On the M62, MB specific intake pipe there is a significant baffle:

There is a standard for removing this baffle, that looks like this:

Supposedly real world experience is that this adds intake noise, and helps with flow at the top end of the range.

I can believe that Mercedes would certainly look to control resonance noise over modest power gains.

Thoughts?

Also, just to add to the discussion, my max target rpm is 14k as well.  

Another note on modification strategy is that at 150k miles, this SC has wear.

So the mods for rpm probably won't be AS detrimental to IAT as if the blower was new.

A lot of the forum posts on the internet for these SC's are 10 years old now...

... I'm probably 30% compensating for wear and 70% boosting / scattering parts.

That would be a 100% guess.

In reply to a_florida_man :

Porting the SC seems like way more risk than potential reward to me, especially this close to the competition. If the car hangs around a while longer, that would be to time to dig in & start experimenting. 

Pete Gossett said:

In reply to a_florida_man :

Porting the SC seems like way more risk than potential reward to me, especially this close to the competition. If the car hangs around a while longer, that would be to time to dig in & start experimenting. 

Funny you say that.... I've been scaling back the porting plans, sticking to mild port matching and smaller 'improvements'.

Lots left to do....

a_florida_man said:

In reply to FooBag :

The M62 application on my Mercedes is one that has the intake on the end of the case, and the supercharger is mounted on the side of the engine, like an accessory. 

Here is a photo from another car to illustrate.

The small end of the triangle is about 1.5 inches from the ends of the rotors. The porting plan I had proposed was based on porting jobs like these in the MB community.

Before your post, the greatest concern I had was to keep the triangle sides parallel with the angles of the rotor lobes and to maintain the coincident timing of the two lobe to triangle side alignments . Your suggested porting plan would make it such that the triangle edge would no longer align with the lobe line. Do you have an opinion on this? I know very little about supercharger pressure wave dynamics and I'm trying to do more good than harm....    ....trying to. Is the 1.5 inches of rotor lobe that is tucked into the case past the outlet sufficient to prevent air from recycling, thus raising IAT?

Thanks.....

 

 

 

You do have a good point on the idea of matching the angle of the lobe with your porting.  Would it make a difference?  Probably a tiny bit.  The scale was deceptive, so you're probably good opening the point of the V if the rotor centerlines are back in there as much as you say.

I think your inlet pipe porting should be your priority right now.  Opening up flow into a positive displacement blower like is definitely going to help.  It would be tough to screw it up, whereas you can screw up the outlet.

FooBag said:

You do have a good point on the idea of matching the angle of the lobe with your porting.  Would it make a difference?  Probably a tiny bit.  The scale was deceptive, so you're probably good opening the point of the V if the rotor centerlines are back in there as much as you say.

I think your inlet pipe porting should be your priority right now.  Opening up flow into a positive displacement blower like is definitely going to help.  It would be tough to screw it up, whereas you can screw up the outlet.

Confirmed with ACTUAL measurement, 1.5" from the V to the ends of the rotors.

In addition to the intake baffle (which is now gone), there is a very small ammount of port matching to do to the pipe, and some work to be done opening the throat of the SC intake port.

Another string of 'ifs':

If it still runs

If it doesn't blow up

If the mods produce more airflow than the injectors can match

Then:

If I need to control fuel pressure to the 'power valve':

If I don't:

Note for posterity, the red nozzle will be drilled and taped into the TB elbow, and the jet under the an3 fitting @ the nozzle is adjustable.

Polishing Headlights.

Rebuilding a supercharger.

Painting a coil cover.

Installing a wide band o2 sensor.

Building a homemade auxiliary fuel injection system.

Simultaneously.

In a tropical storm.

I AM  a_florida_man!

More boost (2 or 3 psi)

Getting to be pretty peppy.

Lots of success!!!

UH-OH!

Too much maybe...

This is leakage from the front crank seal. I think it's blow by induced. 

I've learned a lot about the design of this car, and now it's teaching me about it's age.

It isn't very excited about the new operating parameters. At 22 years old and 150k plus miles, more is not better.

I think I understand, I was up for a lot more in '98 than I am now as well... so we will reach a compromise.

I'm going back to the old pulley, and I'm ordering a front seal just in case.

I'm pretty sure the lower combustion pressures with less boost will eliminate this leak.

This isn't all bad. 

As I was concerned about to begin with, the IAT did get a little high, and today is a cool day.

Any warmer outside and the IAT would almost certainly cause knock or power loss.

I am going to retreat to a position of fun, and ENJOY the Challenge.

Doesn't make a lot of sense to go blow it up, trying to move from 55th to 54th, lol.

Me : "What did you do today?"

Also Me : "I undid most of yesterday."

Good news.... I WAS getting a net 4 psi of boost.

Bad news, it was HOT so the net air mass was not as big as 4 psi sounds.

Better news, car no longer needs a diaper and is still sort of peppy.

I think I'm at my mechanical baseline for the Challenge.

Now to make things look better.

Many small steps, when applied enough times in the same direction, can lead you a long way

sleepyhead the buffalo said:

Many small steps, when applied enough times in the same direction, can lead you a long way

"...in the same direction..." This seems to be the hard part!

Thanks for the encouragement.

I’m starting to worry that I might have to setup a delivery address at the racetrack for Amazon. 

In reply to a_florida_man :

That would not be a first...

So, since I decided to un-break it, I have, of course been trying to think of ways to break it again.

I need help. Seriously.

Thinking again about cheap supercharger tricks....

The SLK230 Gen1 M62 uses a PWM driven air diverter valve to blend and control boost.

Previously I was overdriving the compressor, and basically making more boost than could be vented with the diverter wide open.

This made for LOTS of VERY hot air which is not efficient, especially with a stock air to air inter cooler.

I think that If I could command the flap fully closed at or near WOT, I might find a little boost left that has not been used due to conservative load / boost mapping in the ECU to compensate for pump gas, weather, etc..

I found this.

It looks like 100% duty cycle 12v will command the valve shut.

I'm thinking about using a relay to cut out the ecu driver PWM 12v dc signal (ecu protection) and supply 100% Duty Cycle 12v.  (constant 12v DC) to the valve.

If this results in a lean condition I can still install the homemade "power valve" injector....

However, I think that I found the MB Bosch ECU and injectors did a good job keeping up with the overdriven supercharger, so unless there is a miracle of immaculate induction I won't need it.

Thoughts?

In reply to a_florida_man :

Sounds like a great idea!

For next week...

In reply to Pete Gossett :

I know you're right, but it feels so wrong.... 

Maybe, we'll see, this isn't quite as invasive as the last hack... 

Basically making yourself a push to pass button, or overboost on demand.  Sounds like a good idea, or at least one worth trying.