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NSU NSU is offline
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Join Date: Apr 2010
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1200cc air cooled NSU forced induction w/ ITBs

Hey, there sure seems to be a fair bit of knowledge here about air cooled motors, forced induction and ITBs.. so I figured I'd post.

I've got NSU 1000 project(s).. and I'm considering options.

Since I have a low compression (best guess atm 8:1) 1.2 liter motor forced induction is on my mind.

I'm thinking blow through ITBs.. It seems that Jenvey is the best for this.

What I'm unclear on is pros and cons on Supers vs Turbos setup like this in a rear engined car.

One advantage I can think of for a super, is you can mount it farther forward (intake points towards front of car on the NSU).

Is there a thread that hashes this all out that I missed?

Thanks!
Old 04-09-2010, 11:17 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)
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Hmmm...not specifically.

Roots Superchargers are belt driven from the crank, use spiral screws to generate pressure. They are typically great off the line and build immediate pressure, but tend to peter out on top due to heat generation from poor adibiatic efficiency. Centrifugal Superchargers are a middle ground between roots chargers, are also belt driven but use a similar mechanism to a turbo as it uses a vane wheel to build pressure. They build pressure a little slower than a Roots, but are more efficient on top. They both respond and build pressure quickly since they are mechnically dirven, versus being exhaust driven.

The turbocharger, which is exhaust gas driven, can be a little laggier than a supercharger, but modern turbos are lightyears beyond old units. They spool very quickly, typically can produce much higer pressure than a supercharger, but also require more fabircation, since you ahve to plumb the exhaust system for them.

There is no right answer, but assuming your tiny motor is built to rev, I'd go with a small frame turbo like a Garrett GT2056.
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Old 04-09-2010, 12:03 PM
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NSU NSU is offline
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I'm leaning super because I can get all the weight on the nose side of the engine. I see that Seadoo centrifugal supers are both cheap and sized right.

Would I have to worry about overrevving, or mid throttle with a centrifugal super and blow through ITBs? A BOV maybe?

I want it mostly as my wifes daily driver
Old 04-09-2010, 05:54 PM
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NSU NSU is offline
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I've picked up an M62. It looks like it will flow more than enough air at 1:1.

I'm considering setting it up so that max engine RPM = max efficient blower RPM

The blower would be unthrottled, the boost would be cooled and then go to a log with 5 throttle bodies. 4 for each cylinder and a 5th with no injector, with the throttle plate sprung to waste at X psi. If I meter the air between the throttles and the engine, I'm hoping this setup should work well (but noisy).

Waste air would be directed over the cylinders.
Old 04-26-2010, 07:18 AM
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