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IT LIVES!!!!!

I drove it! It runs! It drives! It stops! It has no more power than before!


OK, heres the deal. After the rag eating fiasco, I reinstall the supercharger back in its proper place. Now I could either go home or finish the damn job! Guess what I did.

Obviously I finished the job. I couldn't help myself.

So.... Final installation was pretty straight forward. I had spent a few hours earlier in the day drilling, tapping and installing all my various vacumn spots, crankcase breather spots, nitrous hole and BOV pipe. I had gone and picked up all neccesary hoses and connections when I accidentally fed the supercharger the rag.

Other than some tight spots, everthing went in like a charm. The only problem, and I mean only problem was the location I had chosen to put the BOV in the pipes. I had set them up WAY too close to each other so the bend was too tight. And I was short hose.

Since I couldn't hook up the BOV right now, I simply decided to hook the two sections together so this way I was not going to cause problems with too high a pressure.

I finally started and idled the car, with the supercharger clutch off. It ran about 80% compared to normal, because the normal airflow was constrictdd, but still ran fine. Revving the engine was completely normal.

I flicked the switch to turn the supercharger on and the idle picked up about 300 rpm and ran about 90% normal. Hit the gas and it takes right off! Sound great. When you lift off the gas, it sounds just like a BOV.

So I shut up the shop and head for home. Test drive a ways with the charger off. Runs great (or at least about 90%)

Flick the supercharger clutch switch and expect great things.

Nothing.

WTF?!?!?!?!?

It accellerates just like a NA, but when I let off the has, the boost guage just jumps to high heaven!

So what is the problem? No fucking BOV. Since I am venting back into the intake without a BOV, when I actually get on it, the boost is dumping back into its own airstream. The only time boost actaually registers is when the throttle plate closes and it spikes.


But....It still works!

The only reason I did not install the questionable BOV that I own (the bosch one) is that I was short proper hose. I think that I will just bite the bullet and get another Bosch BOV new and test tommorow.

Still fun.

Goodnight, I am about to pass out from exhaustion.

where is your boost gauge reading from?

thats very cool, cant wait to see pics and a vid

boost is reading off the piping just before the throttle body.

AAAAAAARRRGGGHHHH!!!!

All this time and money.

All this hope.

And I got squat.

Jack Shit.

Bleah.

Nothing is broken, everything works. I just seem to have the same power as before. At this stage I just don't get it. I am a little depressed.

There are quite a few variables of course to why I am not seeing an increase in power. Just have to sit back and think.

What size is the Mercedes 4 this comes from 1.9? What about a smaller pulley? It must be bleeding somewhere. Could it be pipe volume causing a delay? Are the rotors damaged or could the clearances be off? Are they actually turning?

Just thinking aloud and hoping something could be of help, though they're probably obvious suggestions.

Steve

The supercharger is from a 2.3 liter engine. It very well could be that the undersized crank pulley is a problem.

The charger is blowing hard, but what is "hard enough"

It could be bleeding somewhere, but with this low boost I wouldnt think it would be that harmful. I could be very wrong though.

Can you find out what diameter the mercedes drive pully is?

yeah that makes sense, it could and probably is pulley related as it still is spinning just enough to create boost when the throttle plate is closed. Also would it be better to have the boost gauge after the throttle plate? Like in one of the manifold runners, since that's the actual boost your cyls are seeing?

I have moved the boost gauge to post throttle body. Then I fucked up thye connection so no boost guage for now.

I installed the BOV that was in question. It works. Only it seems to work all the time. I think. I actually havent driven it yet but I am ever the pessimist and suspect this certainly doesnt help.

Crap.

Ok relax... first get the boost gauge set up, after the TB, to see what kind of boost you are getting. Oh yeah figure out the BOV, if it's open all the time you get no boost = No Power.

Try reading boost at the manifold rather than before throttle body

Cheers

Its the pulley stupid.


Just like a turbocharger, the supercharger boost depends upon a certain rpm range. In my case, it looks like optimum rpm is 14,000. I was pushing a maximum of 6,500. ie nothing. The underdrive pulley I had was 4" diameter. The compressor pulley is 3.5". You do the math. Crap.

So I re-installed the stock pulley, spent another $22 on another belt, and took it out for a drive. It works! Not great but the power is felt. With the stock pulley installed, I can get the compressor up to about 9,000 rpm, or basically another 15 hp. Not alot, but at least I am getting something to work and now know why.

Next step is to have a custom crank pulley machined out of aluminium to about 8" in diameter. This will be very tricky but I can do almost all the machining myself so I can make it very lightweight but strong.

The other option is to make a new double power steering pulley where the section attached to the crank is smaller, and the section attached to the supercharger is larger. This unfortuneatley would mean I would need to redo the intake.

Either way = more money. Then again More Money = More Power.

I also may have the supercharger pulley milled down about .5" which is the maximum it could be milled down.

What about getting a smaller pulley for the supercharger? If you get a larger pulley for the crank, wont that make everything else turn faster? Like the alt, ps, and ac. Do you know what the max those pulleys should turn?

The supercharger is clutch driven so you cant change it. this is because the magnetic part is inside the pulley, so the pulley diameter is dictated by the magnetic part of the pulley. I did see a smaller pulley made for the mercedes superchargers but A- they were like $500 and B- may not have been for this particular supercharger.


My fears for making a bigger crank pulley would be A- an exploding crank pulley. B- Overdriving the alternator and power steering. Solutions for this would be to just get smaller alternator and powersteering pulley. Those I can personally make. It is the larger crank pulley that my lathe is too small for.

I dont have ac, so dont have to worry about that. I have considered getting rid of the powersteering too. We shall see.

you think you could use the AC part of the crank pulley since you aren't using that? Like only make that part larger, or something?

Ok , now a rough performance review.

It definately works. If you floor it it first and then flick the switch at 4000k, the car jerks forward like you hit nitrous. This was just a test though, obviously you want it on from 0 to 6500 rpm.

If you go to this site,
http://automotive.eaton.com/product/eng ... rs/M45.asp

you can see the compressor map. While not the same as my supercharger, I suspect it is very close. So basically, as the rpms rise, so does the power, with no spike, it just goes faster and faster.

I suspect that right now I have a bout a 10 to 20 hp increase. Not much but something and it is noticable. With the larger pulley, it will be worth all the time.


Now the noise. LOUD. Since I dont have an integrated throttle bypass valve (not the BOV) all air must come through the compressor. At this point I also have a suck ass BOV, this leaks I think even at boost, and when I let off the throttle, it sounds like a very large angry farting BOV.

The compressor noise itself is also very loud but cool sounding.

The compressor at this stage is activated by an on/off switch located on the dash. This is so that I can activate the supercharger as long as the rpm is below 3500 rpm. My fear of having the supercharger come on only at WOT, is that I have heard of belts snapping when jerked into action too hard. I still need to do some fine tuning obviously.

Since the AC and the Alternator sections are the same, and I dont have the ac, I will just turn a new crank pulley that does not have the ac section to keep weight down.

I have the set up for the belts and the intake currently all adjusted for the current belt location. If I were to have to move the supercharger back, it would mess some stuff up.

Hey look what I found. I previously said that my supercharger did not have a throttle bypass vavle for when not on boost. It turns out that the clutch works as this. ie, when the clutch is not engaged, the air is just coming though. I was doing this, just didnt know this was the answer.

Here is the quote.

"One disadvantage of this internal compression ratio is higher parasitic losses during off-boost operation. A Roots blower can be bypassed with a simple butterfly valve at part throttle and the only drag will be the mecahnical movement of its gears and lobes (which accounts for only about 0.3 hp according to Eaton). A Lysholm compressor, on the other hand, will continue to compress air as long as it is being turned, even if a bypass valve allows that air to be recirculated. The only way to eliminate a Lysholm compressor's parasitic drag at cruise is to let it stop turning via a clutch. (Ironically, the Eaton Roots blower used by Mercedes-Benz uses a clutch instead of a bypass valve, despite this being the more complicated solution. Mercedes does things its own way.)"

Final picture now in bottom of original thread.

Ok, while I still need do a few things to tighten the system up, the word is GO!

With this particular Eaton supercharger, a WOT switch is perfect. There is no need for a BOV. There is no need for an idle bypass valve. The thing is pretty perfect.

Since I installed the WOT switch and removed the BOV, the power is great, even with a too small crank pulley.

Go WOT and the boost just builds super gentle but faster and faster. No hard spike unless you creep up the RPMs without going WOT and then stab it, then the power does hit hard, exspeccially in first and second.

Let off the gas and there is no repercussion or need for a BOV because the compressor is instantly shut off and free rotating.

You may remember that I said the supercharger max rpm is too low. It is. Once I install the 8" custom crank pulley, the power will be outstanding. However, as it is, I can chirp all 4 tires off a hard start. When doing a drag start, I will have to be careful not to burn my clutch.


OK, now how it works with nitrous.

INSANE. OK, not really. But I cut my current nitrous shot of 80hp in half to 40 hp, and I get the same performance. So while the supercharger is not giving me what a 40hp shot of nitrous does, when you combine the two, you get more. ie 1 + 1+ = 3. This is because the nitrous cools the air charge.

The final potential. Intense. I feel that once the crank pulley is sized correctly to the supercharger and with duel stage nitrous, I can easily be putting out 250 crank hp. And since the supercharger power map is a straight diagonal line the strain on the drivetrain is going to be "minimal"

My prediction, I will be a 14.2 second car at about 95 mph in the trap. Not to shabby for a car that started out with a best of 16.6 at 79 mph. And all for a cost of about $1200. Plus some time. Lets see if I can do it.

Cool, I still think you'd be better off using the AC part of the pulley just made larger. Have you calculated how fast your alt and ps pump will be spinning at WOT with an 8" pulley? What did you ever do about fuel and timing control? What gauges are you using? I can't wait to see a vid

OK, fuel management is needed.

But, it is cheap and easy. It is mechanical versus computer.

I noticed that the AF readings were just slightly low. No detonation or anything but the digital read kept slipping a little versus reading constant while on boost.

I decided to wire in the fuel solenoid from my nitrous solenoid with a small fuel jet. It was wired directly to the supercharger so it would only turn on when the supercharger was on at WOT.

Perfect, .7-.8 readings on the AF digital reader. And a bit more power or so says the butt dyno.

So basically if the supercharger kit makes it to sales (everyone cross their fingers) it will include a fuel solenoid and an injector that is welded into the intake. Basically just a fifth injector.

As soon as my new 7 to 8" pulley is turned, for maximum boost, I will have to take it out to the dyno and really tune it with the fuel jets.

How much will this whole thing be all told? Maybe you should try the $2005 Challenge by Grassroots Motorsports. Get some GR2s (maybe a deal on a used set) and I'd bet you'd kick some ass.

Steve

I just got the custom crank pulley back today. $240. $10 more than the damn supercharger! It took the machinist 4 hours @ $60 per hour to take a lump of aluminim ($10) and attach it to an existing aluminium underdrive pulley ($55) so basically I spent $310 on a pulley! Ouch!!!

When (not IF DAMNNIT) the kit get fabricated, it will NOT have an oversized drive pulley, but rather a step pulley off of the powersteering).

Anyway, I installed the crank pulley and turned (I have a small lathe so can turn small pulleys) a new 3" altenator pulley so that the new belt speed doesnt toast the altenator.

I left the powersteering pulley the same as it is barely touched by the belt. I am guessing that it will start to slip if pushed too hard, which doesnt affect performance (at this stage).