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Supercharge?

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RM_Sprite

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I am a new member & Restoration of my first car is about to begin! I'm getting ready to build a 1275 for my 62 sprite, and install a supercharger mainly because I have a steep 15 mile mountain road to climb when coming home - I have found (3) "bolt on no mods" choices but have no experience in the SC arena. These are the 3 I found - Has anyone out there any experience with any one of these or SC's in general?

Hi flow Supercharger :
https://www.hi-flow.com/

Jonspeed Supercharger:
https://i203.photobucket.com/albums/aa48/jonspeed4minis/supercharger.jpg

https://www.jonspeed4minis.co.uk/shop/index.asp


Moss Supercharger
https://www.mossmotors.com/Browse/PlateMe...componentID=112
 
Hi,
I've given my impressions on the other bbs. KCBugeye1275 is another forum user with a Moss kit. You may need to send him a private message since he doesn't check-in as often as some users. I do not know of anyone here using either of the other two kits. However, I have read about (on other bbs's) people using the hi-flow MGB supercharger and they have nothing but rave reviews for the support they received from Hans.
 
What type of eaton charger was used in the kit shown? and what modifications were made?
 
IMHO as a mechanical engineer, and from a thermodynamics point of view, stay away from Roots type compressors. Both the Jonspeed and Moss compressors are that type.

The Hi-Flow looks like a good unit. It uses the double screw compression which compresses air along the length of the unit. As they mention on their website, there is no such thing as taking any unit and fitting it. They must be painstakingly dimensioned for each engine type and size. The result is a smooth compression of air and therefore no excessive compression losses or heating of the intake charge. Also there are fewer friction losses in the screw type.
 
The A-series engine doesn't lend itself well to an intercooler. That isn't too bad a thing, as intercoolers only disperse your expensive energy in heating ambient air. The good thing with intercoolers is that the intake charge is not excessively hot. While not using an intercooler, it is of paramount importance to keep the intake charge as cool as possible. That is best done by not heating it up excessively to begin with. -> DONT use a roots type compressor.
 
Heat does become an issue. But when running low boost levels and bypassing (off throttle) the heat is not as much of an issue. But when the boost is increased or there is a bunch of on throttle driving the heat becomes an issue and the timing must be retarded. I think the hi-flow unit is a better solution if you have the skills/time/money to build an engine for this purpose. However, the Moss unit is usable (with modest gains) on many types of stock and slightly modified engine.
 
I guess I'm pointing out that the integral bypass in the Eaton unit is good for a street driven car because when at constant speed under no load the compressor is by-passed and this keeps the temperature lower. Add yes... moderate boost is all that is needed for significant power gains because it rams fuel/air charge into into the the awkward(IMO) A-series head.

And... I sure you know... higher boost doesn't always equal higher power. The boost is measured in the manifold. I can increase boost by spinning the compressor faster ... or changing the cam to limit the duration of the intake valves. Obviously, the latter will do nothing to improve power even though it creates more manifold pressure. It becomes a balancing act of many variables/functions. Too much overlap on the intake/exhaust and you are blowing the charge out the exhaust pipe. Too hot of a charge and you end up detonating early and holing pistons.

The A-series is a poor choice of motor to try and supercharge if you want ultimate power. But using a supercharger on it for increased torque and HP for street use is viable. Again... is it worth the money? I'd probably do it again. I've learned a lot from it and it has motivated to start planning a turbo system.

I'm not trying to sell anyone on the idea, but I don't think it should quickly be discarded/dismissed either.
 
I'm currently running a Rayjay turbocharger on a built-up 1275 w/5 speed. Even with the problems of 91 octane, retarded timing and rich top-end needle profile requirements, it flat out kicks butt. It easily pulls away from a Weber/1380 with the same gearing. Its very "streetable" and in fact serves as my daily driver to work and back. I get over 30MPG on the highways. People who haven't tried it rush to caution about every aspect of the current set-up, "wet-turbos are bad", "pump gas is too low octane", "charge-robbing is a big issue".
All BS, as this car has had a wet turbo since the early 70s and performs better than any of my other LBCs.

I'm currently building a new set-up to test out. Megasquirt with ignition control, Subaru 1.8L throttle body w/injector and sensors. This should finally get the full measure of the turbo. It should be in bench testing within a few weeks. I'm still gathering up all the peripheral parts.

Glen Byrns
 
Sorry I got into this late, but here is my two cents. First, Glen, it looks like you are on a path to a lot of fun, hope you get to the party at the lake. Second, I have been fortunate to have some very good performance oriented friends and lucky enough to havew a motor prepared for the SC. Everything was done except going with corilla(spelling?) rods. Since I didn't plan on running at high rpms, I couldn't justify the extra cost, and it has been pricey. All that said, this car is a blast to drive. The power is over a very broad band of rpms and although I haven't had it over 6,000 rpms, it still is pulling hard all the way there. Highway speeds it will pull hills in 5th with ease. I did find a hill in the Ozarks it didn't accelerate on at 60, but. I hope to keep this car forever and then give it to a son. I have found money spent today on the BE several years later doesn't seem so pricey.
 
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