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Rear mount Turbo  Rate Topic 
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 Posted: 04-24-2019 12:31 am
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mgreaves
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I've been toying with the merits of installing a correctly sized turbo at the rear, near the spare tyre (or in place of the spare) and plumbing back to the existing air filter under the hood (or installing a filter un the cavity of the rear bumper. Pressurising the carbs like the lotus rather than installing injection.
I know there are pros and cons with this concept, as the forums are full of arguments for and against a rear mount system. What I want to know is has anybody done this to a Jensen-Healey yet?

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 Posted: 04-25-2019 06:31 am
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Esprit2
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If there is a 'pro' to such a set-up, it's far out-weighed by the cons. First and foremost, such a system would have huge turbo-lag.

For an example of a good turbo set-up on that engine, look at Lotus' own 910 turbo. Yes, I know it won't fit in the Jensen-Healey, but look at the parameters that make it work. The exhaust manifold is as short as possible, putting the turbo right behind the head. Then a short runner goes directly to the boost plenum. All that was done to minimize the total volume in order to minimize turbo lag. Moving the turbo 8+ feet back would add a lot of volume, all of which must be pressurized by any boost change before it can be effective at the valves.

A very short-run, front engine Brazillian car called the "Emme 422T" used the Lotus 910S engine, but with a special exhaust manifold that placed the turbo down low, to the left of the engine. Something like that would be a better solution for the J-H than mounting the turbo at the rear of the car.

Attachment: Emme 422T Engine Bay 75.5kb.jpg (Downloaded 37 times)

Last edited on 07-02-2019 05:44 am by Esprit2

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 Posted: 04-26-2019 05:16 am
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Esprit2
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Or Supercharge it...

Attachment: supercharger.jpg (Downloaded 78 times)

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 Posted: 07-01-2019 03:42 am
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mgreaves
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Thanks guys I'll look at space under where the headers are

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 Posted: 07-02-2019 05:55 am
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Esprit2
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Here's an example of the 910S exhaust manifold used on the Emme 422T. Front is to the left, which put the turbo down low, just behind the timing belt/ chassis cross-member. Unfortunately, there were only about 40 of them made.

That's a very compact design, and manifold runners longer than that will result in more turbo lag. I can envision an aircraft using a l-o-n-g system like you described, since they pour the coals to it, get to cruise altitude, set the throttles to cruise power, then never move the throttles again until it's time to come down. Cars operating in traffic change throttle position all the time, and require good response.

Regards,
Tim Engel

Attachment: 910S Emme Engine Exhaust Manifold with forward turbo - top-left.jpg (Downloaded 40 times)

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 Posted: 07-02-2019 07:52 am
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mgreaves
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Very interesting, wouldn't be too difficult to make something like that from SS Tube.
Looks like 1 & 4 are ported together as are 2 &3.

I wonder about all that heat sitting next to the cam belt, could be disastrous. A sturdy heat shield would certainly be required.

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 Posted: 07-02-2019 03:04 pm
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redracer
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Just saw this thread; in Atlanta, in 1978, there was a couple of guys named Tom Wyat and Tom Gage(they used to work for Bob McQueen who successfully race a Datsun 2000) who formed a small company called "TURBO TOMS".
They had turbocharged a J-H and just by a stroke of luck, I happened to see the car(they were right next to the C&S Bank I used). I believe the car belonged to someone in Milwukee?? and they were quite irritated as the owner had turned up the boost and fried the engine.
The turbo was in the engine compartment, not in the rear; I have no idea what components they used and have no idea what happened to the car, its owner, and the Toms.
Maybe a GOOGLE search might help.
good luck, bruce

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