Budget Eaton Build
 

So I have a '94 Miata, and I have an Eaton 62 series supercharger off an old Oldsmobile sitting on the shelf. Guess what's going to happen next? (If that wasn't an invite to flame away, I don't know what is).

I'm planning on a hotside system that blows through the stock TB. At least on the first attempt.

The goal is around 200ish RWHP.

The first stumbling block is pulley sizing. I need to know how fast to turn this thing. In it's native environment on the 3.8l engine, it was turning approximately 2.5 times crank speed and making about 9 psi. I would like some real world #'s on pulley sizing and boost for a 62 charger on the Mazda 1.8l engine. From what I have read on various forums it looks like it probably needs to spin somewhere around 1.8 - 2 times crank speed. I can't start to make the brackets until I know where to locate the SC, it all seems to start with bolting on a crank pulley and getting the belt straight to mock things up.

Also, does anyone know a good place to buy a crank pulley? This will be a 6 rib serpentine belt drive with an auto tensioner. Flyin Miata?

Same goes for the auto tensioner. I want an off the shelf unit used on a production car. Any pointers here?

Other than these two items I believe I can make the rest from scratch.

Are you going to run dual throttles?

just call Gary @ track dog racing. hey may have stuff you can use.

95mm Crank pulley
65mm Supercharger pulley

On my MP62 yields 5.5psi max with no intercooler.

With TB in the stock position and not on the charger inlet it's gonna get loud under there.

Flyin Miata now carries the old BRP / Stage One Tuning superchargers. They should have pulleys, tensioners etc.

No dual throttles at first. I may add that if it seems necessary. I'm not sure how fast the factory SC bypass opens, but I'm thinking I may need a BOV. An intercooler may be on the list down the road also.

jeff_man, what pulleys are you running to achieve 9psi?

And please, anyone that chimes in with a MP62, give your pulley ratio and boost achieved.

65mm or 67.5mm, i will have to check, it's good for 10psi but on my set up and motor it's 9psi then jumps to 10 at the last ~500 rpms when vvt changes.

The best crank pullies come from FastForwardSuperchargers.com, simply because they had a better toothed design that pretty much negated belt slip compared to others. To start out, there are a lot of SC users that have upgraded. You could easily purchase used pullies for cheap in the for sale section. Member named Satisaii is selling a 120mm for like $50 right now. For most MP62 owners, that's a little on the larger side for about 11-12psi.

If you can build everything from scratch, no reason you can't build a bracket for any OEM style belt tensioner too. Go to SummitRacing and search for "Hayden Tensioner". Tons of styles. I haven't been able to confirm, but I'm 95% sure the one used by SOT is the Hayden model 5547. I searched every other pic, and none of the rest looked even close.

Sorry, forgot to add:
115mm Crank pulley
65mm Supercharger pulley
Approx 10psi once above 5k rpm.

120/60 and I get about 11psi, but that was on the old motor, dunno about the new one as i've not re-fitted the charger yet!

So far it's looking more or less like-

1.5 : 1 gets you about 5-6 psi

2 : 1 gets you about 10-12 psi

The factory GM pulley on my charger is 72mm. I'd like to keep this if possible for the greater belt contact surface. Plus it's paid for. So I guess I'm in the market for a 130 or 150mm crank pulley. Preferably 150mm, which will turn it almost exactly 2 : 1.

RunninOnEmpty- Thanks for the pointer on the tensioner. Yes, I'll make the bracket. But there is no need to build *everything*. The spring loaded arm and pulley I will buy, just want a nice easy to fit piece.

Begi's coldside setup mentions something about a F350 truck unit?

They are the latest company using MP62s and have the latest design. I'm sure you could use almost anything since you're homebrewing it.

Maybe this will help you, maybe not:
http://www.cardomain.com/ride/2667914/5
Look for member 924_nick on M.net

thought about doing a similar build with a e36 325i.... not a daily driver project imo.

Just don't expect him to call you back when you leave a message.

Good luck it how much is your budget?

Running with a 4-rib setup....

Stock 77.5mm nose pulley, and the stock 130mm crank pulley.... Getting approx 7.5ish PSI with the TDR IC....

Dave,

I have probably the same setup and get almost the same PSI.
Solid 7. sometimes up to high 7

Also, take a look at this table if you haven't yet.
http://www.trackdogracing.com/websit...lley_chart.htm

You will definitely need a BOV if you're leaving the TB in stock location. I know a couple of guys who run a M45 with stock TB and they all run BOVs. Otherwise you could damage the blower.