Thought it'd be useful to update people on my supercharger project.

Previous threads can be seen here:

Supercharger finally fitted

Its been hard work and I wanted to give up several times, but now it goes very quick.

Since that previous thread I've added a 2nd throttle body before the supercharger. This works in tandem with the original throttle body. Balancing the 2 has been crucial to get it to run smoothly. The 2nd one must open at exactly the same time and the same amount as the original, I have them connected by another cable.
This result of this is reduced inlet temps and quieter running.

I also experimented with taking the air from the by-pass valve through copper pipes to under the front spoiler in order to act a mini intercooler for the bypass valve air, however this didn't make a lot of difference. I've discovered that a bigger vacuum pipe to the by-pass valve lets them open more and therefore also reduces noise further.
I've also moved the MAF sensor back to before the blower and again it runs much smoother now.
I've added water injection at 60% throttle. This is a home made kit with an aerosol nozzle glued into the MAF behind the sensor and a 2nd washer bottler pump in the original location. This is triggered by a micro switch attached to my 2nd throttle.
This BIGGEST improvement has been changing the injectors to those from a Volvo T5 turbo. They flow a lot more fuel and I can adjust it all with my Apexi S-AFC controller. I was going to install a rising rate fuel regulator but I don’t think I need it now.
I’ve also has added a resistor to the air inlet temp sensor to give slightly more fuel as well as adding a resistor across the water temp sensor for the fans to keep engine temps down.
They cut in at 95degC now instead of 110degC. Helps when the air con is on.

The upshot of all this is that it really flies now. I'm running 6psi max at the moment.
I now plan to install a chargecooler and will get a bigger crank pulley made to compensate for the loss of boost. Air inlet temps at motorway speeds are still over 120degC (because of the by-pass valves) but around town and on boost there are only about 70degC.

I still want to try and make it quieter even though its a lot better now than before. I have plated the supercharger inlet with lead and also added 1/4 wave length pipes to reduce noise.
Biggest difference though was simply from covering the pipes with sound proofing.
I also aim to improve the by-pass valve by maybe adding a third one or trying to make a mechanical operated one controlled by an accuator so it stays open longer at small vacuum.
There are some pics to follow.

Here's a pic of before I moved the MAF.
I actually left the existing MAF where you see it now and added a 2nd one where you see the inlet quarter wave length pipes (black plastic ones- not used now).
Also attached is picture of the resonator chamber I made. It has a baffle plate inside and fibreglass filling. It helps to reduce noise further.

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A couple more pics during development. Ignore the cardboard and plastic pipes you might see in the pics, they were for experimental purposes only.
You can see the extra idler pulley I made and the 2nd throttle body. Getting an adapter fabricated for this was a nightmare.

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Is there a reason you didn't just use a blow off valve with a feedback after the MAF?


Cool, literally! Just be carefull you don't Hydraulic.


Your boost pressure is slightly messing with your fuel pressure at the injectors when you don't have one. as long as you keep your boost pressure below 10 psi, you should be fine.

Is your air temp sensor after the SC?


Sounds like a good plan. Very nice job! Thanks for the detailed description and pictures. Have you had a chance to dyno it yet?

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Current Stable:
01 ML55 AMG
92 500E (a few mods)
87 300E (lots of mods)
00 Chevy 3500HD Diesel Box Truck
68 18' Donzi Marine
06 GT i-Drive7 1.0 Mountain Bike (with GPS!)

PREVIOUSLY OWNED:83 300SD, 87 420SEL, 88 420SEL, 90 420SEL, 86 560SEL, 86 190E 2.3-16V AMG, 94 E320

Hi,
Not gonna Dyno it till after I get chargecooler installed, inlet air temp concerns me a lot. Prior to installing the supercharger I noticed inlet temps on the standard car could be up to 30deC higher than ambient due to heat soak. I removed the undertray from the car and also all the rubber sealing strips from around the bulkhead. This gives improved airflow through the engine bay. The downside of this is the internal heater blower fan now sucks in all the hot air as the inlet vents are under the top of the bonnet, thankfully I just switch the aircon on to recirculate mode.
My inlet air temp sensor for the ECU is in the normal place after the blower.
I have a separate one installed near it with an internal digital display.
I've also added heat wrap to the exhaust manifold which works very well which suprised me.
The location of the MAF and the by-pass valves I have messed about with loads. In various locations. The main thing about the 2nd throttle is it reduces the air the by-pass valves have to recirculate and and makes it a lot quieter at idle because there is hardly any air to compress. Through my research I figured out that most OEM and aftermarket superchargers have the throttle before the blower. I had to leave the original one in place because it controlled to many other things such as idle and cruise contol.
When my project began I could only get the the car to run smoothly if I place it after the MAF. Then after I added all the quarter wave length pipes and the resonator chamber these upset the flow and it wouldn't run. So when I moved it back to before the blower the difference was amazing as was the throttle response. I've concluded that the size and amount by-pass valves open are crucial in keeping the noise levels down.
I've gone to such great lengths to record and analyze the frequency of the noise and calculate the exact size of the quarter wave length pipes and the resonator chamber. Previuously I just couldn't drive the car because the supercharger scream was too great, now its very muted.

The chargecooler I plan to fit is one of the cylindrical type, it'll fit in place of the original pipe that runs across the engine. The only downside is it'll be the most expensive piece of kit I've had to buy for the project as its all be done on a budget. Apart from the supercharger which I also got quite cheap most of my parts have come from breakers yards. I also bought a MIG welder in the end (first time I'd used one) and haven't stopped using it since. Now I can make anything.

One final big probem I get since adding the bigger injectors is hot starting. I have to crank it a few times with my foot on the gas pedal. Also when I engage drive or reverse at idle, the revs drop slightly which I think is normal, but then the engine surges quite drastically unless I put it back into neutral.
Nothing I can't live with but its just annoying having to engage neutral everytime I come to a stop for just a few seconds, but on occasions it doesn't do it and runs fine.

Thanks for the tip on the Volvo T5 injectors. I recently bought a set of Bosch 280 150 945 injectors which flow 30#/hr. They are vitual drop-ins for the stock Bosch 19#/hr injector (280 155 209). The nice thing about the 280 150 945 injectors is that they are commonly used in modified Mustangs so they're available everywhere. Ford Motor Sports even sells the injector under their part number.

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2002 E55 Stock
Sold my project car: 1993 300E (3.2L) Blower running 0.8 Bar, Re-badged E32 Kompressor, Apexi Piggyback ECU, 310cc injectors, 255LPH Walbro Fuel Pump, Water/methanol injection, Quad SS Exhaust Tips, 3" SS exhaust with high-flow Cat, 17" Monoblocks 225/45/17, Brembo BIG Brake upgrade, Euro-headlamps, clear corners, Euro-tail lamps, keyless entry, CD AMPs Subs etc...

Photos: http://share.shutterfly.com/share/received/welcome.sfly?fid=c20c2dad4373aa89&sid=0CbuXLVo5cMXFg