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DIY M62 supercharger build... stage 2

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pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
After finally getting my car on the local dyno I am now working on stage 2 of its development. Stage 2 will be a larger exhaust system and a larger carburetor. The exhaust system is already in place. I went with a 2 1/4" pipe and 2 glass pac mufflers. The rear is an oval Magnaflow and the front is a small diameter straight muffler, also from Magnaflow. No dyno results from the change but seat of the pants indicate a fairly large increase in performance. The sound is very deep and low compared to the old 1 3/4" system.

The second major mod is to fit a Mikuni HSR 48 flat slide carburetor.

To do this I had to cut off the less than ideal intake setup that I previously welded to the M62 supercharger to fit an SU HIF6. It worked well but it's hardly an ideal path, flow wise. I used a 4" angle grinder and a 1/16" thick cutoff wheel to rough it down and then took a slice off with my bandsaw. It was really tricky to figure out just where to cut it. I cleaned it up with a giant file my farrier gave me. It's about 20" long and is the coarsest rasp I have ever seen. Weighs about 2 pounds! It works fantastic on aluminum.(it's a hoof file) I rubbed the end on big sheet of coarse sandpaper to get it really flat.

Now I'm ready to weld on a few lugs to tap for bolting on a back plate to bolt the Mikuni to. I'm heading out to the shop to practice with my gas torches. I decided to bolt on the end plate so I could remove it to replace the needle bearings if I ever need to. They were in blind holes but I cut off enough of the back housing to expose the ends of the needle bearings. Now I can just tap them out with a hammer and socket if need be.

Adrian



Home built Eaton M62 Supercharger with 7.6psi boost, 8:1 compression, custom "supercharger" cam from Schneider Cams, Mikuni HSR48 Carburetor, Chevy Cavalier 1.6 rocker arms, Maxspeeding rods with Teflon wrist pin buttons, custom aluminum cold air intake, CB Performance computerized ignition, Fidanza 9 pound flywheel, 1.44 exhaust valves in 48cc chamber head, matched manifolds, 2 1/4" exhaust system.

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pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
The Mikuni will fit in the available space. First pic shows it balanced roughly in place. Second pic shows the housing ready to have lugs welded to it for the bolt on rear plate. Third picture is my practice lug for the bolt holes needed for the back plate. It's just a blob of weld done with a gas torch. I bashed it with a hammer to make sure it was solidly attached. Then I threaded it and tested that by torquing a bolt down good and tight in it. Now I just have to do it for real in my SC housing without melting a big hole in it. No pressure.

Adrian



Home built Eaton M62 Supercharger with 7.6psi boost, 8:1 compression, custom "supercharger" cam from Schneider Cams, Mikuni HSR48 Carburetor, Chevy Cavalier 1.6 rocker arms, Maxspeeding rods with Teflon wrist pin buttons, custom aluminum cold air intake, CB Performance computerized ignition, Fidanza 9 pound flywheel, 1.44 exhaust valves in 48cc chamber head, matched manifolds, 2 1/4" exhaust system.



Edited 1 time(s). Last edit at 2018-11-27 08:21 AM by pinkyponk.


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pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
So... I tapped out the rear needle bearings in preparation for welding lugs on and found that the bearings rattle. That seemed like a bad thing. There appears to be little to no grease in them. I looked closer at the seals and they have some damage. I put grease in there so it must have been washed out by the air/fuel mixture due to the damaged seals. I'm thinking I'm pretty lucky to have checked them before anything catastrophic happened! I'll have to order new bearings and grease.

Adrian



Home built Eaton M62 Supercharger with 7.6psi boost, 8:1 compression, custom "supercharger" cam from Schneider Cams, Mikuni HSR48 Carburetor, Chevy Cavalier 1.6 rocker arms, Maxspeeding rods with Teflon wrist pin buttons, custom aluminum cold air intake, CB Performance computerized ignition, Fidanza 9 pound flywheel, 1.44 exhaust valves in 48cc chamber head, matched manifolds, 2 1/4" exhaust system.

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RAY 67 TOURER Avatar
RAY 67 TOURER Ray Marloff
Fort Bragg, CA, USA   USA
1967 MG MGB "My Girl"
Very impressive. You really do need to get a proper hobby you know. Supercharging is so yesterday. RAY

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glbishop Avatar
glbishop Gary Bishop
Spring Hill, FL, USA   USA
In reply to # 3849532 by pinkyponk After finally getting my car on the local dyno I am now working on stage 2 of its development. .........
Adrian

How did Stage 1 do on the Dyno ?

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pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
114hp and 121 pounds ft. at the wheels @7.6 psi boost. Probably should order a new snout pulley...

Adrian



Home built Eaton M62 Supercharger with 7.6psi boost, 8:1 compression, custom "supercharger" cam from Schneider Cams, Mikuni HSR48 Carburetor, Chevy Cavalier 1.6 rocker arms, Maxspeeding rods with Teflon wrist pin buttons, custom aluminum cold air intake, CB Performance computerized ignition, Fidanza 9 pound flywheel, 1.44 exhaust valves in 48cc chamber head, matched manifolds, 2 1/4" exhaust system.

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glbishop Avatar
glbishop Gary Bishop
Spring Hill, FL, USA   USA
In reply to # 3849769 by pinkyponk 114hp and 121 pounds ft. at the wheels @7.6 psi boost. Probably should order a new snout pulley...

Adrian

Nice.
That would have NA output at about 75hp



Edited 1 time(s). Last edit at 2018-11-27 03:09 PM by glbishop.

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gray Avatar
gray Graham Moore
CAMBRIDGE, CAMBRIDGE, UK   GBR
so in post 1, are you saying the big diameter exhaust rear end alone made a noticeable difference/?

do you have stock or oversize exhaust valves adrian?

also - did you use the uber-expensive supercharger grease? or other?

G

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pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
In reply to # 3849838 by gray so in post 1, are you saying the big diameter exhaust rear end alone made a noticeable difference/?

do you have stock or oversize exhaust valves adrian?

also - did you use the uber-expensive supercharger grease? or other?

G

The new exhaust system is 2.25" throughout, from the Y pipe back... and yes it made a noticeable difference in performance.
I do have larger than stock exhaust valves. (1.4" I think... would have to check) Standard size intakes.
I did use the proper dark blue uber grease.

Adrian



Home built Eaton M62 Supercharger with 7.6psi boost, 8:1 compression, custom "supercharger" cam from Schneider Cams, Mikuni HSR48 Carburetor, Chevy Cavalier 1.6 rocker arms, Maxspeeding rods with Teflon wrist pin buttons, custom aluminum cold air intake, CB Performance computerized ignition, Fidanza 9 pound flywheel, 1.44 exhaust valves in 48cc chamber head, matched manifolds, 2 1/4" exhaust system.



Edited 1 time(s). Last edit at 2018-11-28 06:35 AM by pinkyponk.

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1970RedMGB Avatar
1970RedMGB Thomas P
Lombard, IL, USA   USA
1969 MG MGB GT
1970 MG MGB
I'm curious to see what difference the Mikuni makes in terms of general driveability and overall horsepower. I considered the Mikuni a few years back but I heard mixed messages about it.

Best of luck!

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pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
Welding the lugs on went well. A little pitting but it will seal with a good thick paper gasket. It's under suction anyway. I'm going to have to weld up that saw cut I made by accident. I didn't think it would bother me... but it does. Probably good to have let it cool anyway before tackling it.

The Mikuni will fit the opening pretty much perfectly. The last photo shows the size difference between HIF6 and HSR48.

Adrian



Home built Eaton M62 Supercharger with 7.6psi boost, 8:1 compression, custom "supercharger" cam from Schneider Cams, Mikuni HSR48 Carburetor, Chevy Cavalier 1.6 rocker arms, Maxspeeding rods with Teflon wrist pin buttons, custom aluminum cold air intake, CB Performance computerized ignition, Fidanza 9 pound flywheel, 1.44 exhaust valves in 48cc chamber head, matched manifolds, 2 1/4" exhaust system.


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Denis Avatar
Denis Denis Hill
Bearii, Nth Victoria, Australia   AUS
To give you an idea of the difference , the best I got out of my pretty developed engine was 127WHP and around 135FLB with the SU. I suppose about 150 @ engine. Fitted the Mikuni with no other adjustments at all to the car but enough to the Mikuni to make it rich enough. and it made 140.7WHP. A couple of months later with the Mikuni sorted (it took that long) it made 145.7WHP and 145 pounds torque. We found we got a little detonation with the Mikuni that we did not with the SU and a quick re-curve of the 123 ignition gave just on 148WHP. have to be 175+ @ engine The alteration was to only to take the peak advance out 500 revs higher and 2* off that. Same SC drive ratio as the SU but the increased breathing was worth 1,5lb. This was with the Moss hi-boost pulley and a hi-flow harmonic balance that is very slightly larger, so not a lot of boost. The drive ability is now close to perfect at any speed/load but not without a of of work to get right. Denis



68 B roadster, Daffodil yellow, supercharger, Burgess SC head, SC cam, Mikuni HSR 48 carburetor and engine built for supercharging.

73 BGT V8 conversion starting with a bare shell. Built the engine "3.9L Rover" early in 2016 with high comp pistons and a few other nice bits, plus a T5 ford trans. Started on the body late 2016 and complete late 2017, Did all the work myself, mechanical, body. paint etc.
Finished and going well, great to drive and quick. Now has a nice 3.23 LSD.

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pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
In reply to # 3849852 by 1970RedMGB I'm curious to see what difference the Mikuni makes in terms of general driveability and overall horsepower. I considered the Mikuni a few years back but I heard mixed messages about it.

Best of luck!

Me too! And thanks!

Adrian



Home built Eaton M62 Supercharger with 7.6psi boost, 8:1 compression, custom "supercharger" cam from Schneider Cams, Mikuni HSR48 Carburetor, Chevy Cavalier 1.6 rocker arms, Maxspeeding rods with Teflon wrist pin buttons, custom aluminum cold air intake, CB Performance computerized ignition, Fidanza 9 pound flywheel, 1.44 exhaust valves in 48cc chamber head, matched manifolds, 2 1/4" exhaust system.

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pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
In reply to # 3849801 by glbishop
In reply to # 3849769 by pinkyponk 114hp and 121 pounds ft. at the wheels @7.6 psi boost. Probably should order a new snout pulley...

Adrian

Nice.
That would have NA output at about 75hp

Thanks Gary. I think a decent MGB is considered to have more like 65 hp at the wheels in stock form. I'm hoping for some serious gains from "stage 2". If stage 2 works out well, stage 3 will be more boost.

Adrian



Home built Eaton M62 Supercharger with 7.6psi boost, 8:1 compression, custom "supercharger" cam from Schneider Cams, Mikuni HSR48 Carburetor, Chevy Cavalier 1.6 rocker arms, Maxspeeding rods with Teflon wrist pin buttons, custom aluminum cold air intake, CB Performance computerized ignition, Fidanza 9 pound flywheel, 1.44 exhaust valves in 48cc chamber head, matched manifolds, 2 1/4" exhaust system.

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glbishop Avatar
glbishop Gary Bishop
Spring Hill, FL, USA   USA
In reply to # 3849963 by pinkyponk
In reply to # 3849852 by 1970RedMGB I'm curious to see what difference the Mikuni makes in terms of general driveability and overall horsepower. I considered the Mikuni a few years back but I heard mixed messages about it.

Best of luck!

Me too! And thanks!

Adrian

The flat slide Mikuni is a winner. Awesome carbs.
Just need to jet it for the application and drive-ability will be as close to proper mapped FI as you can get. You can't do better.

As far as max power.... carbs don't make power but they sure can take it away. Proper A/F and flow make power. A 48 flat slide will be a big gulp but the HSR has adjustable accelerator pump linkage and interchangeable accelerator pump jets. The enrichment circuit for cold starts is also a plus.

At some point I plan to switch over to an HSR45. Not in a hurry so I just keep an eye out on eBay.



Edited 1 time(s). Last edit at 2018-11-28 04:57 AM by glbishop.

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