17 Dec 01
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
1 Jan 02
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.
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.
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.
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.
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.
Created by: Dan Houlton
This page was last updated on 14 Apr 2004