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Discussion Starter #1
I have two Eaton m90 I got from the pick a part hooked up to my 302, similar to the ones shown on the website www.toohighpsi.com (I think its down now). The guy on the site used fuel injection, which I'm totally against (computers in cars...thumbs down). I want to know what size carb I should use? Also I don't know if the forced air will work blowing into the carb or the other way around. How much air do you guys think 2 M90 add to the 302?



High nickel Mexican Block
Forged crank
H beam rods
Forged pistons
Crane Cam Hydraulic
Gt40p ported heads
1.6 rollers rocker
Edelbrock Performer intake
HEI distributor (GM Style)
 

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I don't have much to add except: 1. You're nuts! :buck: (I'm kidding, that is not a bad thing) and 2. I think the carb's need to be before the chargers in order to work properly.

Regards,

Bob
 

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Yeah, you need to do a couple of things.
Make sure those particular M90's are okay for a "wet" system, and then mount the carbs upstream. It would appear they are not from Eaton's own warnings.
But, you can do what you want.
All Eatons are “dry”, and designed for use with EFI. Draw-through installations, where fuel will be present inside the supercharger, are deprecated by Eaton (and their service agent Magnuson), and are inherently dangerous as a source of explosion. In addition, the fuel will slowly leach lubricant from the bearings, and dissolve the rotor coating used on many models.
CFM? Depends on the driven gear on the chargers, drive gear on the engine, whether or not your port job on the GT40s will work well with forced induction, etc.
 

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You can get Blow through carbs that are designed to work with turbos or centrifugal superchargers. As a general rule, get one size larger than the engine would need if it were naturally aspirated. If you determine it needs a 650, then go with a 700 or 750, just make sure it is a blow through.
 

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Yeah, either way if he's going to run 2 M90's he's gonna have to get them running by remote mount anyway. $$$

Running a blow through setup requires a lot of carb savvy.
 

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Injection is nice but I'd rather be......wait a minute now --- ain't nuthin' wrong with either!! I think Andy is correct on those M90's, you are going to be in the need of an injection system of some sort. It's not gonna be cheap and you will have plenty-o-figuring to do on final drive setup/actual PSI/and what block work you will need (o-ringing most likely)....I'd hunt down somebody that already has a setup and see waht info you can glean from that....it will save you a lot of guesswork.
 

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I work for Eaton, but not heavely involved in the supercharger side of the business. Mike Sitar was the managing engineer that did the twin setup on the too high PSI site. He left Eaton a few months ago to help his wife with her business. His brother still works here and I think he has the car now, but it is in pieces. He did the setup on a 351w which was basically a stock motor. No o ring and he blew the head gaskets once tuning the setup. You will have to run larger pullies to slow down the chargers especially for a 302 ( smaller displacement). Notice the larger pullies in the photo. I think figuring out the correct ratio is how he blew the head gaskets. Running a carb.....well like Bob said...your nuts. He had a programmable fuel injection system that read off the O2 sensors and still had a tuff time tunning it in to run correctly. He was also running an air to water cooler setup he had in the trunk and would fill it with dry ice for runs at the dragstrip. twinSC.jpg
 

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Discussion Starter #9
I know the tuning is gonna be a bi**h, but I'm always up for a challenge, and what a challenge thats gonna be. So the theory with the pullies is, the bigger the pulley, the less boost? The other problem is the darn distributor in the way. What companies sell distributors with the 90' degree shaft?
 

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Discussion Starter #11
ahh thats what I was looking for. Google searches have proven to be pretty useless nowadays with all the paid advertisers jocking for top spots. So we got pulley issues, fuel distribution issues, PSI issues. Is there any type of mechanical fuel injection setup. I have no issues with fuel injection, but I do have issues with computers in cars.
I will work out each of these problems, one by one. First I have to find out a better way to mount the superchargers and drive the pullies, then I'll move to the next issue.
 

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On Mike's car he made a couple of plates that mounted off the intake manifold bolts and the heads as well to hold the chargers. He had an issue under hard throttle, the two chargers pulling in towards each other making the belt losen up and start slipping. He later made a cross member that went between the two chargers to hold them apart at the same distance under load.
 

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I do wish you all the best in this effort but I'd be remiss if I didn't mention that distant memories of a certain young man and his dreams for his '68 came up when I started reading this thread.
 

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Ah, it's fun to daydream about hot rodding.

Without a computer, you're basically marooning yourself in 80's tech. A blow through carb with the superchargers mounted remotely and feeding into the carb inlet is probably the simplest way to do it. That way you don't need (maybe) a new distributor. You just need a manifold, the carb, the piping for the superchargers, the bases, pulleys, belts, and mounts for the superchargers to bolt to the engine.
http://www.jegs.com/i/Paxton/769/1001864SL-P/10002/-1
That'll give you some visual. The one pictured is a centrifugal type supercharger, whereas the M90 is a roots style (longer). So, you'd need to mount them appropriately and then pipe in the compressed air to the carb inside the enclosure.
 

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I bet they would have the tendancy to walk inward .... that's a ton of torq when shes under full spin I bet. Did he ever seem to get it to a point where it was long term stable/driver car? Ultimately that's the kind of reliability you'd want - and the hard part.
 

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Yes he did for a couple of months, then got bored with it and decided to see how fast he could make it go. Being a heavy T-bird he stripped out most of the interior and sound guard stuff. Removed all the options that didn't make it run, and started increasing boost. He was running low 10 sec quarter mile passes, and if I remember correctly it broke into the high 9's. Very impressive launch seeing a T-bird get the front tires in the air. He got kick off the track for not having the proper safety equipment to run that fast. He finally broke the bottom end as it was stock and not beefed up at all. I don't think the car has been touched since.
 

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Discussion Starter #17
Wow!!! Now that's what I'm talking about!! I'm building the engine for occasional drag racing but on the street I think as long as I don't drive with a lead foot, I should enjoy at least a year out of it before a rebuild. It's totally fun for me so I wouldn't consider it a pain really... I'm going to go to M&K Metal works and start pricing so metal plates from their scrap pile. Time to break out the cutting torch and grinder!
 

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What's wrong with computers in cars? A programmable PCM will allow you to dial the system in. Otherwise it's a crap shoot and all of the crap will cost lots of money.
 

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Discussion Starter #19
I don't like computers in classics...haven't you seen the Terminator movies? lol!!! If the computer fails, I can't rig it, patch it, glue it, or fix it...your just screwed until u have $500 bucks for a new one.
 

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Discussion Starter #20
I'm going to mount the superchargers similar to this set up in this pic DSC08100 copy.jpg I figure if I can mount the charger s on a hat that sits on top to the carb. but my issue lies in securing the superchargers where the hat rest on the carb lightly.
 
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