I like pulleys...

[Sykohtic]

This is something down the line for my '87 325is... many of you already know what I'm about to address I'm sure. I don't want a turbo. I want a supercharger. There are a few of these rare sort out there, the one's that go against the grain... and quite honestly, I'm in love wit the rarity, perks, and potential for a supercharged M20. However, it seems there are a lack of kits due to the lack of popularity over the turbo, but still... I know I'll have to compile a custom kit. But hey, getting help with this is what I'm here for right?

Here's a list of the components I think I'll need and questions associated with each if there are any...

-The blower- I'm looking at Vortech mainly, though a Rotrex would do the job nicely as well... opinions on models of blowers?
-Miller MAF conversion- Not really much to add to that...
-Blow-off Valve- Turbo guys I know you know of good brands, help me? lol
-Obviously, custom mounts and charge piping
-Crank Pulley- this is a tricky part... this will likely need to be custom fabricated as well. Schneller had these when they made their kits several years ago, though the guy on the phone said he didn't think there were any left since they stopped making the kit... recommendations? Maybe there's something off another car that came factory supercharged? Like a GM vehicle? As satanic as that sounds...
-Intercooler- again turbo guys, I know you know, lol
-Injectors- Okay, this is another tricky beaver... I've got absolutely zero clue whatsoever on this one... help...
-The ECU tune- the big kahuna. The pink elephant in the corner. This is going to be a requirement. By this point I plan to have the car cammed and have a header and such to really support the FI, so to tie everything in and make the car run correctly, this is a MUST. So, I need a dyno and someone good with doing ECU modifications and remaps. Again, recommendations are begged for, though I understand the opportunities are limited due to location

Sorry in advance for a long post. I might be forgetting some stuff, just bring it to note in your posts. Thanks in advance for the help, I know this probably isn't really conventional, but just help where you can, if you will.

[jaywood]

Why are you set on a supercharger?

A lot of the stuff you're going to need depends on how much power you plan to make, i.e injector size.

Tuning is simple, PM whodwho here on r3v and talk to him about his PNP megasquirt setups. He is running one on his supercharged m20.



Good luck. Keep us updated.

[Sykohtic]

Why are you set on a supercharger?

A lot of the stuff you're going to need depends on how much power you plan to make, i.e injector size.

Tuning is simple, PM whodwho here on r3v and talk to him about his PNP megasquirt setups. He is running one on his supercharged m20.



Good luck. Keep us updated.

I'll do that then. I'm really set on a supercharger because primarily I want boost over the whole rpm range. Turbos are cool, and for a long long time I planned on turboing my car. But instead of the sudden rush of torque and power, I want power over the whole range. Plus, seeing as for at least now, the car remains an auto, I can't really do much for the rpms to keep a turbo spooled outside of using the gear lockouts, which I have to get a shifter rebuild kit as my gear selector has more play than a loose cannon.

Power goals are around 250 to 300 bhp. The closer to 300 the better. I don't really want much more than that for now, as that's plenty for my applications. I know a supercharger will help it get there with the right setup, the Schneller kits were claimed to boost at like 7lbs the car up to 260 bhp or so with some mild supporting mods on stock internals. Not sure how true that is.

I'll definitely send that PM though, thanks for the input!!

[Ether-D]

From what I understand, the centrifugal type superchargers (rotrex, vortech) are a lot like turbos in that they don't make much boost at low rpm and come on real strong at high rpm. So there's that. I'm in the midst of a eaton M90 build (roots type). Good luck to you. Somebody has to get one of these finished and do a writeup.

[SmokeE30]

For a a blower setup your gonna have to convert to a serpentine belt setup using m5x pulleys as v-belts and blowers don't work we'll together but thankfully it has been done before so just keep searching and reading up on stuff. I looked into a supercharged m20 briefly and decided it would be much easier to start with a 24v motor if you want a blower.

Best of luck

[whodwho]

I'll do that then. I'm really set on a supercharger because primarily I want boost over the whole rpm range. Turbos are cool, and for a long long time I planned on turboing my car. But instead of the sudden rush of torque and power, I want power over the whole range. Plus, seeing as for at least now, the car remains an auto, I can't really do much for the rpms to keep a turbo spooled outside of using the gear lockouts, which I have to get a shifter rebuild kit as my gear selector has more play than a loose cannon.

Power goals are around 250 to 300 bhp. The closer to 300 the better. I don't really want much more than that for now, as that's plenty for my applications. I know a supercharger will help it get there with the right setup, the Schneller kits were claimed to boost at like 7lbs the car up to 260 bhp or so with some mild supporting mods on stock internals. Not sure how true that is.

I'll definitely send that PM though, thanks for the input!!

There are pros to both turbos and SCs and either can get you at your power goal. it all comes down to what you can fab up and what your power goals are. A turbo would be simpler in that there are more ready made parts for the M20 and many proven setups running and are easier to get higher HPs. You need to research compressor maps to get one that fits your requirements. With a SC you will have to fab up mounting brackets and a pulley system and usually takes relocating the alternator and possibly loosing the PS.

I would say the auto is more turbo friendly then a SC, a turbo needs more of a load to get it spooled up and a centrifugal SC is more RPM dependent. My opinion and experience is the dependability of the stock HP22 will suffer under boosted conditions as will a stock clutch at anything over 250 HP

-The blower- I'm looking at Vortech mainly, though a Rotrex would do the job nicely as well... opinions on models of blowers?

First is deciding on the type of SC and how that fits your expectations. You are mentioning centrifugal SCs but as mentioned those are more turbo like in that they have to spool up. Roots or twin screw are more linear and will deliver more to your description of "over the whole range".

The centrifugal ones are a little more DIY mounting friendly, the Rotrex would probably be the best for the size but are expensive and not rebuild friendly. The Vortech/Paxton ones are the most common now and you can find used head units but are on the big side unless you go/find a V5 G Trim would probably be the best one. A V1 will have a louder whine and a V2 will be a bit quieter.

A roots type would fit your requirement and you can find Eatons all day long for cheap but are not as mounting friendly and can be an awkward size depending on the model. These can be a noisey, it is best to have the TB before the SC.

A twin screw have the best efficiency and would be my first choice but depending on your budget these are a bit more pricey and not as common.

-Miller MAF conversion- Not really much to add to that...

These seem to be a nice clean easy setup but I don't have experience with their setup but they don't seem to be as boost friendly as other management systems available and it seems that people are not be able to get these dialed in 100% and will leave it at that.

-Blow-off Valve- Turbo guys I know you know of good brands, help me? lol

If you go with a Miller MAF setup or a chip with a AFM still you will need to go with a recirculating setup, going with just a blow off causes issues

-Obviously, custom mounts and charge piping

This will be a 100% custom fabrication as the only kit available that I am aware of anymore is a Rotrex setup from Europe somewhere.

-Crank Pulley- this is a tricky part... this will likely need to be custom fabricated as well. Schneller had these when they made their kits several years ago, though the guy on the phone said he didn't think there were any left since they stopped making the kit... recommendations? Maybe there's something off another car that came factory supercharged? Like a GM vehicle? As satanic as that sounds...

Another area of custom fabrication, you will want to drive it with a serpentine belt a v-belt will tend to slip with most SC loads. Some have had custom ones made, some have welded pulleys to the existing PS/AC pulley I went total serpentine and removed the PS/AC pulley and trimmed off the V pulley of the front damper and mounted a modified a Ford pulley that had a pulley for the main belt and one for the SC.

-Intercooler- again turbo guys, I know you know, lol

Depending on the setup this can be optional if the boost level is low and you don't try over spinning and generating extra heat. You can control the charge temp with a water injection setup and it helps. Depending where you mount the SC it can be challenging running a air/air setup. A air/water setup is typically what you would use, one for ease of fabbing and there is usually less pressure drop across the cooler.

-Injectors- Okay, this is another tricky beaver... I've got absolutely zero clue whatsoever on this one... help...

Pick your injector size for the HP output expected, depending on the management system you go with you can go larger to give you some room to work with without tuning issues.

-The ECU tune- the big kahuna. The pink elephant in the corner. This is going to be a requirement. By this point I plan to have the car cammed and have a header and such to really support the FI, so to tie everything in and make the car run correctly, this is a MUST. So, I need a dyno and someone good with doing ECU modifications and remaps. Again, recommendations are begged for, though I understand the opportunities are limited due to location...

The tune is the most overlooked part but is the most critical piece and to me the best spent money, as it will determine the final results of all your work. To get the most out if it and keep it the most dependable you will want it dyno tuned. You can dial it in the best you can with a conservative spark map to get it close and then take it to the dyno and get it finalized.

[Sykohtic]

Thanks for the info, I'll definitely be keeping with you, whodwho, for more information and guidance. So thanks a bundle!! I have a lot to consider!