A roots type blower has 2 or 3 'blades' on two interlocking rotors that are synchronized to push air into the intake manifold. This develops 4 to 6 pulses of air per rotation. The screw type is also a positive displacement, but each rotor resembles a worm gear. The air is trapped and compressed as it is forced between the 'screws' toward the intake manifold. It is more efficient because there isn't any pulse to disturb airflow, and the compression takes place somewhat more gradually. I believe the Eaton superchargers/blowers are roots type, but with rotors that are extremely twisted. This avoids the pulsing problem and makes it more efficient.

LOCOSVT

 

The ultimate turbocharger is called a Fan Jet engine!

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adp
#1530
Black '99

 

a turbine powered lightning! WOOHAH!

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brooks
'00 silver "L"

 

Don't laugh about a turbine-powered Lightning. It can be done, and quite easily! There's a firm down in lower Louisiana installing rebuilt turboshafts into cars, trucks, boats, and motorcycles right now. These are ex-helicopter units, which are apparently cheaper and easier to replace than rebuild when the FAA says "enough". A little rebuilding work makes them ready for "ground service". They're tiny (about the size of a 5-gallon bucket) and don't weigh anything at all (a couple hundred pounds), but make crazy power (a tiny one they put in a bike made 400+ RWHP as I recall) and sound great at tens-of-thousands RPM.

There was an article in one of the mainstream motorcycle mags recently (within the last 6 months) about these guys. It focused on the bike (a fierce machine, to say the least), but also showed/mentioned a boat (offshore racer) and a vicious pickup truck (a Silverado, I think). Any of you ready to ante up?

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Silver Y2K Lightning
Bone Stock w/ Duraliner, Ford Hitch Cover

Silver (matching) Y2K ML320 Benz
Burl (ML430) Shift ****

Beater 1992 Grand Prix
Commuter Mule

 

i wasnt laughing... i would like it a lot!
wonder how much it would cost?
hmm... what would i put it in?

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brooks
'00 silver "L"

 

This thread tanked a few months ago, but in the middle of it someone mentioned that a supercharger overcame the 4-5% loss of boost per 1000 ft. that slows down an NA engine.

I always thought this to be true also and looked it up in some of my aviation history mags and they say the same. A P-38 Lightning (had to use that example) maintained the same performance at, say, 30k ft. as it had at 10k ft. due to the supercharged motors it used.

So, a question, why do most of our Lightning owners seem to get slower times in say Colorado than Boston assuming other factors are more or less the same?

Just wondering.

Bill

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99.5 Lightning
Build #247
PSP Chip/Filter
Bassani full system
White/normal options
Tamiya 1/10 scale Bolt
Several old trucks/cars
Thunder & Lightning
Rag Doll Cats
E-mail MOSTOYSINC@AOL.com
Kennesaw, Ga. (Atlanta)

 

I think the difference, at least on ground vehicles, is that although we both have boost, our lower altitude vehicle is "boosting" a higher, or denser air; whereas their air is less dense. The same reason a cool air mix burns better, faster, more powerfully than a hot air mix. We both have boost, but we are boosting more.
Like I said, I think.
Can't explain why it works or if it works differently on an airplane, but maybe they actually 'would' be more efficient at ground level.
Tim

 

Heres a pic of my turbo hayabusa...it is intercooled as well. Hp is 340 at 12lbs of boost. 390-400 at 18pounds.











[This message has been edited by n20boy (edited 09-17-2000).]

[This message has been edited by n20boy (edited 09-17-2000).]

 

A roots S/C sits on the intake manifold and has a longitudinal impeller, a centrifugul S/C is a side off assembly like an altrenator and has a centrifigal impeller, (round disc like as opposed to a roots type which is more like rollers). One advantage of a roots blower is that being on top of the manifold, it feeds it's boost directly into the manifold, a centrifugal has to rout e the pressure through some kind of plumbing for lack of a better term. Because of this, the actual boost needed for the same result is less by a factor of about 1/3, so a roots pumping 6 lbs/inch is givving the effect of a centrifugal blowing 9 lbs/inch, give or take. Manufactuerers use roots types because they are more reliable by several times. The boost from a roots type is also much more consistant at the manifold.

 

A roots also creates alot more heat than a screw type charger(aka autorotor). Superchargers in general are not as efficient as turbos but make up for it with instant throttle response and lots of -power right away. Its easier to make more power with a turbo than a supercharger due to its design and efficiency.

 

Damn thats a fast looking bike, whats the estimated top speed?

{edited after thought]

I have heard of twin turbo set-ups, such as one going a 2k rpms say, and the other coming on at 4k rpms, would a super/turbo charge setup work? Once the rpms got to 3k or so, the supercharger would open its bypass and then the turbo would take over?

Another think I have heard of are hydra-chargers. New age kinda thing, its supposedly has the efficiency of a turbo, but the idle responce of a supercharger. Its hydralycally powered, kinda like your power steering pump.

[This message has been edited by Tundra (edited 09-18-2000).]