Bought this huffer from a T-bird Super Coupe. Wanted a Scott, that was $2K, this was $125. I think I can make it work, have to figure out how to mount a carb, however this, an Eaton M90, is made for 3-5 liter engines. My little 60hp is 2.3 liter I think. And my engine probably turns half the peak revs. So before I get serious, will this thing be efficient if I turn it around crank speed?
I've seen online a very effective kit of 2 on a 302 Ford, which was home built. BBK was going to offer such a kit for Explorers, in fact. There was some licensing issue, and they never did. I think you have the right instincts- spin it about half as fast as the 3.8 V6 it was on. Grassroots motorsport hold a challenge where you build a car for the price of the year, so in 2014 they will race cars they have receipts for $2014. These m90 chargers have some history there. A triumph Gt6 and a BMW 320I come to mind but there have been a half dozen others. They have a forum.
YEEHAW!!! Nothing like some boost for a kick in the pants. Only one quick trip around the block and kept it under 5psi, mostly due to a wood carb adapter and a piece of string through the cowl vent for a throttle. But it works, now it comes back apart to do it right. Some questions: 1. Can I connect the vacuum brake to my pancake distributor between the carb and blower to work as normal? 2. I need some sort of blow off valve for backfires. I'm thinking just a stud in the blower adapter plate with holes drilled around it, a fender washer and gasket over the holes, a spring on the washer and a nut on top to adjust pressure. Good enough? 3. What would be a guess at a safe limit for boost on a stock Ford flatead? 4. Is there any way to limit boost other than pulley ratios (and right foot).
I put one of these on a corvair last years... They are a 2.7/ 164 ci motors. I got some simple math equations for figuring the correct size of pulleys you will need. Ill get them tomorrow... answers the best i can... 1. Yes you must out it before the supercharger. 2. Sounds like it needs some tuning. I dont know of a blowoff valve for a blower, but you could probably get one for a turbo and put it under the blower
and my son hit the enter button... 3.I would say a max of 5 psi should be fine... Thats a max, full throttle underload. The blower will not create full boost not under load. IE reving it in neutral... 4. No the pulley sizing will be your best bet. And displacement for your motor is 136 cubic inches or 2.2 liters
Thanks summersshow! I don't have any backfires. This is my first blower experience and from the reading I've done it seems you need a blow off or pop off whatever you call it valve so if you have a backfire it doesn't crack the blower or manifold. Waiting for your formula for pulley size. I just have an old alternator pulley on the blower for now.
Blow off valve , bleeds boost at a pre set level to prevent over boost on a turbo. Your backfire pressure relief valve is most necessary with a cog belt drive. Depends on your drive if you must have one. The OEM figures any back fire will cause the rotors to spin and slip on the belt. Most are a spring loaded plate, springs are strong enough to resist normal boost pressures but give on a backfire. Be mindfull of where you put it because scary stuff can fly out of it when it does what it's made to do.
Thanks 31V, good info. I'm just using the stock wide V-belt so perhaps I don't need the backfire valve. Saves me some work, 3 straight days and nights of this and I'm pooped.
. we made a burp valve for a O/t car manifold using a piece of 3/8 aluminum plate 2x4 covering a hole 1 3/4 x 3 3/4 and held down with a pair of briggs 5 hp valve springs they are about 25 psi when snugged down ( 5 psi pressure in manifold ) , and will allow it to burp if it backfires , and you can adjust the pressure by tightening them down more if the supercharger is making more boost , backfires are hard on a screw style blower like that the Fuel management system on them cars were set up rich to help prevent backfires plus the blower and manifold were dry . you could use aluminum snap studs like they do on the roots ,
Pulley Ratio(PR)= C(14.7+B+I)/14xV C= ½ engine capacity in CCs (136 cubes is 2,228.64 and that divided by 2 is 1114.32) B= Boost in PSI (Lets say 3 for this test) V=Blower volume in CCs (an Eaton m90 is 90 in3 which than turns to 1,474.83 CCs) also to figure this you need the volumetric efficiency of the blower (Eaton m90 is 84%) so take 1,474.83x.84=1,238.86 which is your blower volume… I= Allowance for valve overlap (example for every 10 degrees of overlap allow 5% of the boost)… Info I have says its 40 degrees… So… I=40x.05xboost (3) -> I=6 So… PR=1,114.32(14.7+3+6)/14x1,238.86 PR=1,114.32(23.7)/17344.04 PR=2,709.38/17,344.04 PR=6.4/1 pulley Ratio That means you want your drive blower pulley 6.4 times larger in CIRCUMFERENCE than the drive pulley. Circumference not diameter Ignition timing….a rough rule…. retard the spark by 3 degrees (crankshaft) for each unit of compression ratio by which the actual compression ratio (taking into account boost) is raised. So you start with a head which is 7:1 compression ratio and you get an equivalent compression ratio of 9:1 (using the calculation formula) then that is increase of 2 units which would equal 6 degrees retard. In this case if your static timing is 5 before tdc I would change setting to tdc. I don’t suggest you use static timing after tdc. This rule is only a guide. lots of influences come into play. Theres my gazintas...
A blower pulley 6.4 times larger in circumference than the crank pulley? That could be a problem... gee the blower didn't look that big. Appreciate the effort. Is that close to what you ended up with on the 164 CI Corvair?
O poop... I messed up on my math somewhere... I never said I was the smartest guy... So… PR=1,114.32(14.7+3+6)/14x1,238.86 PR=1,114.32(23.7)/17344.04 …28638 PR=26,409.38/17,344.04 PR=1.52/1 pulley Ratio…
That's OK, I got lost somewhere around blower VE. Whew I like that better. Just to confirm is that 1.52 crank/1 blower or the other way (blower overdriven or underdriven)?
Crank Turning faster than blower... Pulley Ratio(PR)= C(14.7+B+I)/14xV is represented by Pulley Ratio(PR)= Engine RPM/Blower RPM Its hard to slow that info down. I do appologize. And remember all those numbers are just for example. You should find out your over lap and how much psi you can actually run...
gad you caught that summer , otherwise it would have been funny to see that 18" dia drive pulley sticking out of his hood LOL
Thanks again guys. I suppose another way to look at it is if there's too much boost, slow it down. I'm happy to at least know it's all feasible. I'm curious how supercharging will affect efficiency. flatheads being low compression with marginal breathing it seems like a good idea.
I can't wait to see how this turns out. What are you going to do to help control detonation. I'd imagine that you're running low enough boostntomwhere you don't really need t think about water/ methanol injection. Posted using the Full Custom H.A.M.B. App!
I would find an eaton off a lightning. They have the inlet on top which would allow easier carb mounting.
Yes me too! Engine overheating may be a problem also. I'm not going for huge gains with a stock block so hopefully 91 octane will suffice. Sure enough. I'm planning to mill the top of mine, today actually, for two Strombergs so either way some work involved.
I read a little about those, something about letting boost bleed off under deceleration? Doesn't seem to be an issue on hot rods?
Some of the eatons have those, controlled by the boost control solenoid. What it does is relieve boost back into to the top of the blower. If you read the patent on the valve and what it's purpose is for its pretty clear. Has nothing to do with overboost protection or backfires. You can put a small enough pulley on an eaton and blow some shit up or break plenty of parts.
The boost control solenoid also provides your over boost protection. I have ran plenty of HEATONS well over 18-20 psi. Your problem then is you are over spinning the blower and creating too much heat. That is why there is a need for an air to water heat exchanger.
im pretty sure you cant run fuel through it, dont remember why.( seals, maybe.) I put one on a vw, blowing thru the carb... http://www.youtube.com/watch?v=YcXI5hVwDUQ
I don't see why you couldn't. Here is a kit made for the flathead that uses and eaton supercharger. http://www.tr-designs.com/Releases/TRD_Release_1.htm
NO NO NO... Thats a big blower an Eaton 112... Talk about a big pulley... I used a side draft weber and it worked great... The throttle body on those T-birds is before the supercharger...
Bob Whitehead (retired GM engineer and flathead guru) has a flathead with a little t bird sc eaton running a single stromberg right into the stock opening in the back. He made a little 90 degree manifold to mount the carb behind and above the blower. Not sure how fast he is turning it. Sent from my MB865 using H.A.M.B. mobile app
That's what I've got at the moment, in fact my manifold is made out of a block of wood since I wasn't sure this whole thing was going to fly. My plan is to copy it in aluminum and plop a second Stromberg in front of it. Note old generator pulley, the string throttle and boost gauge hose running through the cowl vent. Went for one short ride, saw the boost, felt the extra oomph and parked it for tear down. Funny, I made no adjustments to the carb and it idles way faster now even though it's pulling a vacuum.
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