Lotus Elan

Anyone used forced induction on a Twin Cam

PostPost by: Chancer » Tue Oct 14, 2014 7:36 pm

That looks a bit agricultural.

I'm not surprised that you had drive problems seeing the tiny bracket holding the huge supercharger mass, the harmonics must have been interesting to see but I would prefer to have been looking from behind a lexan screen!!!!!

food for thought though and good on you for having a go.
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PostPost by: Tahoe » Tue Oct 14, 2014 7:45 pm

So I just calculated the boost required at sea level for 180 flywheel HP, using an air to air charge cooler. peak power at say 6000 RPM will need approx. 7.5 psi. At say 7000 ft elevation boost is still right at 7.5 psi. If you are looking at 160 HP boost would be approx. 4.75 psi, and 170 HP would need 6.25 psi. Now that's pretty low boost. I think I'm much more optimistic than most about doing this. I believe the Twink is robust enough to do this at low boost pressures, but the added expense of fuel injection, ECU, special fabrication, etc. can really add up fast.

As far how to route the turbo, well you could do as shown in the beginning and route the turbo forward and then run the exhaust back. The turbo itself would be smaller than the T4/T3 hybrid shown. Oil feed/return and center housing water cooling would be a slam dunk. The charge cooler could be right by the grill with the radiator moved forward behind it. I'm confident it could all be packaged without too much of a problem.
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PostPost by: gus » Tue Oct 14, 2014 10:28 pm

John

would love to see the rest of that induction setup
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PostPost by: Tahoe » Wed Oct 15, 2014 4:24 am

gus wrote:John

would love to see the rest of that induction setup


In my minds eye it's all very clear, unfortunately my wallet can't see it as clearly as my minds eye. Doing a turbo system is pretty straight forward as far as selecting the components once you know your intended HP and use (track, street, drag race, etc.). It becomes a little more involved when programing the ECU, but even an ECU novice like me has done it once before, and in the end, it was extremely rewarding. I guess I need to start buying those lottery tickets again.
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PostPost by: john.p.clegg » Wed Oct 15, 2014 6:41 am

Gus
There's not really much more to see, u/j on the crank bolt , drive via square tube to u/j on the "blower", feed pipe from the "blower" to the plenum...didn't really want to pressurise the incoming air,just wanted to help it..

If I had better quality u/j's I would have carried on with it ..it did let go once or twice but there was a safety screen between the frame cross-member and bottom of the radiator so no real damage.

John :wink:

I'll see if I have any more photos.
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PostPost by: gus » Wed Oct 15, 2014 12:15 pm

so you were pressurizing stock webers?
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PostPost by: john.p.clegg » Wed Oct 15, 2014 12:23 pm

no,just helping induction..

John :wink:

N.B. the "blower" was a heater fan out of a truck..
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PostPost by: oldchieft » Wed Oct 15, 2014 1:59 pm

if I understand correctly then blowing the air box would apply the same pressure to the top of the fuel in the float chamber.

This would be a well balanced system, and would work well.

Centrifugal blowers don't do much at low speed so it would not give a big gain in low down grunt but would not use much power at low speed. It would give some gain at the top end.

This is all book theory from nearly 50 years ago but I doff my hat to you for doing it.

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PostPost by: gus » Wed Oct 15, 2014 2:10 pm

IIRC Lotus Esprit had specially built Dellorto carbs to handle the pressure
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PostPost by: Chancer » Wed Oct 15, 2014 2:48 pm

oldchieft wrote:if I understand correctly then blowing the air box would apply the same pressure to the top of the fuel in the float chamber.

Jon the Chief


Yes on later webers that have the large vent hole in the filter mounting flange, earlier ones had a castellated vent Under the jet cover.
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PostPost by: bigvalvehead » Tue May 19, 2015 7:20 pm

This is only running approx. 8psi !!!!
http://www.ebay.co.uk/itm/251963772692? ... EBIDX%3AIT
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PostPost by: Elanman99 » Wed May 20, 2015 3:18 pm

111-1178_IMG.JPG and
I missed this thread when it first started but I can add a little to the Elan forced induction topic.

In 1964 I helped a friend install a Shorrock supercharger in his Elan. I do recall it went like stink but it did have some minor problems. It had its heyday, just one! when it won its class (although its debatable whether it was classified correctly) in a local sprint. It got its winning run win in spite of crossing line travelling backwards!

The owner was a supercharging enthusiast and ran as a road car, a frogeye with a full race Formula Junior engine to which he had fitted a blower. He did the same to the Elan with the larger Shorrock unit (C142?) that was mounted in the nose of the car using a drive shaft passing through a hole put into the radiator. An Austin Seven fabric/rubber driveshaft coupling was mounted on three stud in the bottom pulley. The 2" SU carburettor went directly on the blower inlet and aluminium tube and hoses took the compressed mixture to the one-into-four manifold (my handiwork).

As a road car it was great, I doubt it would have had long term reliability and it suffered from the carburettor icing but it was fun. No work whatsoever was done on the engine to prepare it for supercharging and being much younger then neither of us knew much about it, it was all trial and error really.

The reason the car crossed the line travelling backwards was the the rear wheels locked up when the supercharger seized solid. We found at afterwards that the larger Shorrocks blower had an absolute upper rev limit that was a bit lower than the twincam went to!

I still have the SU and the manifold, in fact I fitted them to my S4 when I took the Webers off to overhaul them.

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PostPost by: JohnG » Sun Mar 26, 2017 1:57 am

I have built a fuel injected, turbocharged twin cam and have it installed in my Elan. You will need an electric water pump. I still have the stock mechanical pump, but with the electric pump, it can sit at lights idling and not overheat. It has a modified Toyoto MR2 radiator. the mechanical pump is driven by a tooth belt so there is little side load. I also have it intercooled and use the Megasquirt computer.
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PostPost by: dougal9887 » Sun Mar 26, 2017 6:56 am

Love to see some pictures.
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PostPost by: gus » Sun Mar 26, 2017 12:59 pm

yup without pictures it didn't happen!

You cannot just tease us like that!
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