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DIY supercharger option - with EFI!!!

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Yankeedriver Avatar
Yankeedriver Platinum AdvertiserAdvertiser Joel Young
Albuquerque, NM, USA   USA
Grabbed a moment to drop the engine onto the motor mounts and double-check my engineering on the DIY supercharger mounts... she's all sorted!

These photos show:

1) how the setup looks in the engine bay--right at home to my totally biased eye;

2) bonnet clearance--ample, and I do not see issues with the Bugeye bonnet, though we've got one 'early bird' who will confirm that;

3) belt release works fine--though here I used a small 3/8" bar rather than a ratchet, as there isn't a ton of room for the head of a ratchet;

4) front and rear mount clearance. The latter concerned me, as you've read, for the rear mount is just forward of, but partially over the brake line union. I had replaced mine with a regular 3-way and moved the brake switch to the pedal box. But it looks as if the pressure switch might sit just behind the rear mount. At any rate, hardly an insurmountable issue, as one could just move the union slightly;

5) the shortened lower VW Rabbit radiator hose serving here as the initial part of the top radiator circuit--for down-flow OEM radiators and VW Rabbit cross-flow radiator conversions like this one. Cross-flow radiators of course do not require the thermo housing spacer & GM temp sensor mount I engineered and which you see here, because their thermo housings head toward the lefthand side of the car.

At any rate, with down-flow radiators, and the Rabbit cross-flow conversion, the first of the two top hose photos also reveals where the snorkel comes forward from the blower, thence 90 degrees downward in a vertical plane between the radiator and the belt, and roughly 50 degrees toward the right-hand side of the car (to your left in this photo), to pass through the fascia and connect with the Audi A4 intercooler. Of course, some people may 'opt out' of the intercooler and plumb the other direction, toward the carb.

Cool! I'm now going to pull my engine, take measurements, and get the block and crank to the machine shop. Oh, and also the flywheel to have it re-drilled for the larger Datsun clutch. Can't wait to destroy my old rear tires so I can find some better ones. smiling bouncing smiley

Joel


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mrmg1965 Avatar
mrmg1965 Gold Member Steve Strublic
Peoria, AZ, USA   USA
1965 MG Midget "Gidget"
2011 Mini Cooper S "Nigel Whitworth"
Congrats, Joel! That's a major milestone. It's too bad the heater blower air intake won't fit, but who needs heat? smiling smiley

Steve



http://midget.strublic.net

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Yankeedriver Avatar
Yankeedriver Platinum AdvertiserAdvertiser Joel Young
Albuquerque, NM, USA   USA
In reply to # 3908040 by mrmg1965 Congrats, Joel! That's a major milestone. It's too bad the heater blower air intake won't fit, but who needs heat? smiling smiley

Steve

Steve,

Yeah, it's actually confirmation that the rear mount clears the bodywork as it was designed to do; the front mount was engineered while the engine was still in the car, so zero suspense there. But no less satisfying to see a painstakingly designed part work as intended!

On the heater: actually, the OEM heater box is retained with this conversion--a requirement I imposed on myself from the git-go when doing the early conceptual work, as it gets very cold up here in the NM mountains during the winter.

People have two options. Option 1 - simply put a filter directly on the intake to the OEM heater fan. At least one of the 'early birds' is going that route. Option 2 - replace the OEM fan with an inline racing car ventilator fan, and run the duct inside the fender to the original hole in the front fascia. That is the route I am going. I already run a duct inside the lefthand side fender to direct cool air onto the K&N air filter, as discussed earlier. Here, it's even easier as there's already a hole in the front fascia, whereas I had to cut a hole and install a flange (I think it was Specter brand) to affix the duct hose.

Anyway, it produces a really sanitary setup, and there are nice-looking aluminum body inline fans available in both 3" and 4" diameter. You can see them here: Revotec aluminum inline fans.. But I'm adding a photo.

The OEM cable-operated vane may be retained--which I may do--which is cool, because that way the control on the dash is retained and fully functional.

Joel


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Richb Richard Ball
Everett, Wa, USA   USA
Another option that might work for the heater would be to replace it with one from a 1500 as the inlet is on the other side. There are some differences in the battery trays for different years, but it should work on the 71-74 cars. The core support would also have to be cut for the fresh air hose, but hey what's a little modification.



Rich Ball
'76 Midget
Everett, WA

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Yankeedriver Avatar
Yankeedriver Platinum AdvertiserAdvertiser Joel Young
Albuquerque, NM, USA   USA
In reply to # 3908213 by Richb Another option that might work for the heater would be to replace it with one from a 1500 as the inlet is on the other side. There are some differences in the battery trays for different years, but it should work on the 71-74 cars. The core support would also have to be cut for the fresh air hose, but hey what's a little modification.

Rich,

Depending on where one puts the air cleaner and bypass circuit, that could work. Thanks for the suggestion!

Joel


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Yankeedriver Avatar
Yankeedriver Platinum AdvertiserAdvertiser Joel Young
Albuquerque, NM, USA   USA
Okay, got some emails and PMs asking for fabrication shots and measurements of the rear mounts (I had posted the dimensions for the 'J' pice of the front mount earlier). Again, I'll be getting dimensions to Tyler so he can work up CAD drawings so people can easily replicate these mounts. However, here are some pics from the step-by-step instructions I'm putting together, and which show just how straightforward the fabrication of these mounts really is.

The pics with a ruler or marked up dimensions are sufficiently accurate; the design is pretty hard to screw up as it's just complimentary angles based on 65 degrees. Even if you make the rear mount's center parallelogram too short, you just put washers between the block's bosses and the inner angle iron piece and voila--perfect inboard/outboard clearance of the alternator's case. The overall length of the outboard piece is roughly 11.5".

The materials are all 3/16" mild steel in three forms: 1.5" wide angle iron for the inner piece (really, a 4" long piece is nice to start out with, even though the photo shows a shorter chunk) - you can see it's modeled on an OEM generator mount; 3" wide flat bat for the middle piece; 2" wide angle iron for the outer piece that hugs the blower's housing and provides slotted mounting tabs for its lugs.

I slotted the holes and made the radii in the outer piece to mirror the blower's rotor housing with a $13.00 pneumatic rotary file I got on Amazon, but you can use a Dremel too, as shown in the last pic, but it produces less clean ovals--at least with my aging hands.

Joel


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Yankeedriver Avatar
Yankeedriver Platinum AdvertiserAdvertiser Joel Young
Albuquerque, NM, USA   USA
I got a new question (or one I evidently forgot to answer):

Spridgeteer: "Can I use a stock fan with this conversion?"

Answer: "Yes, you can."

The attached pictures show that there's loads of clearance between the upgraded OEM, multi-blade fan and top radiator hose, for those running down-flow OEM radiators and cars--like the '67 Midget test mule--running a VW Rabbit cross-flow, but whose inlet is also on the right-hand side. The hose shown here, 1.25", is a VW Rabbit lower hose trimmed to place its radius closer to the thermo housing to afford room for the blower's outlet snorkel. This hose is for the high-flow thermo housing; the stock 1" top hose should net even more room at this juncture.

As for fore-aft positioning, the OEM H2O pump pulley is steel and thinner than the A-series 5-rib pulley I designed in conjunction with SmoothFlow, who produces it, and which matches the serpentine crank pulley I offer. The thickness of the aluminum pulley where it bolts to the H2O pump is thicker not only for strength; it also positions the plastic fan very close to where it sits in a stock configuration vis-a-vis the radiator core.

The aluminum pulley's O.D. is .10" less than the I.D. of the plastic fan, so the pulley is designed to nestle into the fan nicely.

All of that said, an electric fan is preferable from a performance standpoint in my opinion--but I must say that the yellow fan looks dandy with the green, black anodized, and bare aluminum bits.

Joel


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Yankeedriver Avatar
Yankeedriver Platinum AdvertiserAdvertiser Joel Young
Albuquerque, NM, USA   USA
Okay, here are a few pics that fill in some gaps in making up the outboard piece of the rear mount, the stock for which is just Home Depot 2" x 3/16" thick angle iron. This piece looks tricky but it is really simple to make--and the design is very forgiving.

The stock cutting photo a couple of posts ago lists 11-1/2" but it's useful to cut the stock at 11-5/8" or even 3/4" if you're using a plasma cutter or not sure of the straightness of your cutting method. It doesn't have to be perfectly square at either end but a big gouge or really slanted cut can yield too short of a piece.

In the first photo, the little 'x' indicates the corner from which all measurements are taken. The remaining photos show the only other critical thing--that you need to end up with 3" beyond the inboard mounting tab where you cut off one part of the angle, because the length that is yielded by doing that forms the mating surface with the middle parallelogram of 3" wide steel bar.

Really, the distance of the holes up from the corner of the extruded angle--1" and 9/16" respectively--is not critical because they get slotted anyway to allow fore-aft adjustment of the blower. It's the distance laterally--from the end with the 'x'--that matters, 5/8" and 7-3/4" respectively, as the resulting span matches the spread of the mounting lugs on the blower's rotor housing.

I've got the 'day job' heating up this week, but should finish up the mounts' photo series this week or weekend and get the CAD drawing stuff to Tyler... and people will be able to easily replicate these at home, or pay someone for ~ 30-40 minutes of welding time to stick together the components folks make up in the garage over a weekend.

Joel



Edited 2 time(s). Last edit at 2019-03-17 08:41 PM by Yankeedriver.


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