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17 Dec 01

Version 1

r0101131.jpg (19692 bytes)Well, here it is finally after several years of wishing and wanting.  My initial foray into forced induction was with fitting a turbocharger to my Amigo.  This actually came to be because I found that the turbo from an '88 Isuzu Impulse would physically bolt on to my engine as they both share the same external engine block dimensions (though the turbo Impulse is 2.0l vs my 2.6l).

I had initially wanted a supercharger, but there were no kits available, the cost to put one on was prohibitive, and the turbo came along as a do-able and relative inexpensive option.  Now though, I've finally found an affordable SC solution using an Eaton M-90.

I would still like a screw type supercharger (Whipple or Lysholm type), but to get one I'd have to buy it new at around $1800 for just the bare SC.  My second choice was an Eaton SC as it came on tens of thousands (if not more) factory Ford and GM cars, and with a little bit of research I've found the one I want.

This particular one came off of an early 90's Ford T-bird.  It is a second generation Eaton M-90 (later T'-birds used the 3rd generation M-90 that's an updated, more efficient design).  This SC is actually quite large for a 2.6l engine, but that's OK as long as I can still fit it.  It just means that I don't have to push it anywhere near it's limits to get the boost I want from it.  Being a used piece, the price was right.  I've seen these go routinely for $300 - $500 on EBay.  If you find one from a junkyard, the price will likely be similar, but I can't say as I haven't looked.

Another option would be the smaller Eaton M-62 from a 90's GM fwd car.  The M-62 is actually a better match for the 2.6, but the GM Eatons use a custom housing that includes the bypass valve molded into the SC housing.  That's a nice feature, but it ends up being much longer and likely too long to work for me.  I like the Ford SC since it's the bigger model, and it's a stock Eaton model.  There is no special housing used on the Fords.


1 Jan 02

The overall installation.Good news! The SC is now on. I've driven it a couple times, but I'm still waiting for a part to come in (a check valve for the water injection system) before I can do any real testing. My first impression is that I'm going to like this very well. When barely moving in 1st at 1400 - 1500 rpm, I can floor it and boost comes up just as fast as I can push the pedal up to about 5 - 6 psi. By 2500 rpm or so, it's reached a max of about 9 psi.

This is actually quite a bit less than I was expecting. Ignoring variables for the moment, the SC was geared to make about 15 psi, and I was expecting maybe 12. Volumetric efficiencies of both the engine and SC, as well as the SC's condition make a huge difference. More than I thought it appears. It may also just be that the SC is so much bigger than what a 2.6 really requires (these Eaton SC's get more efficient towards the upper end of their max rotor rpm). These are not really high pressure ratio devices like a turbo can be, but seem to be happiest and most efficient in the 8 - 12 psi range. Will do more testing to verify all this too.

Showing the tensioner and belt allignment.I did have a problem with belt alignment. The SC ended up being too far rearward about 1/8". The mount for the belt tensioner is also too weak. It is 1/4" plate and is braced halfway up on both sides, but it's not enough. It takes a lot of tension to get the tensioner to move, and it's enough to bend the mount back. For now, I'm running it tight, but not enough to bend the mount. I plan on re-doing the tensioner mount with 3/8" stock and using full bracing to the top. I'm also switching to a different tensioner that I found off a Caddy. Very similar to the Ford Turbocoupe one I'm using, but it's a bit longer and has a square hole to put a breaker-bar / ratchet in to pull the pulley back.

The new, smaller SC pulley.I ended up machining a new pulley for the SC on my mini-lathe. This one's about 3/8" smaller in diameter, is only 6 ribs, and is offset forward about 1/8" more than the stock pulley was. This will give me more boost, will have better alignment and will have better belt retention since there's now a shoulder on both sides of the belt. I've only done rev-tests in the garage, but everything looks good. With the stock pulley, the belt would dance back and forth across it's 8 ribs, and sometimes rode up the front shoulder of the pulley and folded over on itself.

The water injection nozzle and intake manifold adapter.I originally had the water injection nozzle in the outlet of the SC. I didn't like that though, as it's right above the rotors. Normally, this would be no big deal, but when I first drove it, manifold vacuum would suck water through the nozzle all the time and the SC ended up with a little puddle of water in it. Not good, but it didn't hurt anything.

I did two things. I moved the nozzle to the intake manifold, and I ordered a 1 BAR check valve that goes in the water line. This will keep engine vacuum from sucking water through the line, but will open up when the pump kicks in under boost. Thinking back, I should have placed it in the intake manifold adapter instead. There is room there for it, but it wasn't on at the time and I didn't think about it until afterwards. BTW, I used a shop vac with a water trough shaped extension slid into the intake manifold to catch and suck away metal shavings while I drilled and tapped the manifold.

Side view.  You can see the throttle body and the bypass hose at the rear of the SC outlet.I also learned that manifold vacuum is very strong. I originally used rubber hose to connect the SC outlet to the intake manifold, but it collapsed. Same with the bypass hose. They'd puff out when I hit the throttle, but would collapse so far as to nearly close off completely and stall the engine when the throttle wasn't open. I made the SC to intake manifold pipe from 2.5" exhaust tubing mandrel bends. The bypass valve much tighter so I'm using 3/4" PVC right now as the 90° elbows fit. I don't think heat will be an issue, but I'll watch it when I start driving.

That's it for now. More later. BTW, if you're familiar with my website, you'll know my pictures are really poor. I got a new digital camera for Christmas (Cannon S300 Elph) that I took these with. They are sooooooo much better I can't even believe it.

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