Another RD

[lecroy]

I stumbled onto another RD site....


http://eindiancompanies.com/unsorted/dragpics2.htm

Fun little bikes.

Veggie dave's is cool too. Read the paint section.

http://www.veggie-dave.co.uk/racing/frame.html

 

[KEITH KRAUSE]

I bought a new RD400 in '78. I loved it! I sold it when I moved up to my 1000. I wish I had kept it now. Great bike and lots of help out there with mod's, etc.

 

[Mark Harrop]

I've been thinking of taking my 77 rd400 and making a "supermoto" style bike...twin FMF style dirt bike pipes, monoshock, new forks, frame mods, 17" tires....
not enough hours in the day.....

 

[KEITH KRAUSE]

Yup. Those are the magic words, "not enough hours in the day". :roll:

 

[lecroy]

While I was in Ohio I saw an RD with N2O. I never saw it make a pass. The first run it bent the axle.

 

[Mark Harrop]

ever see one with a turbo?

 

[lecroy]

No. Do you have any pictures?

 

[lecroy]

I was sorting pictures and came across the N20 injected RD. Would have been great to see it run.

 

[humhead]

My first bike was a 72 R5C. I found it next to a dumpster. Great little bike. I put an RD motor in it - I wanted the extra gear. The thing is too small for me. I'm going to sell it next spring.

Terry

 

[Mr. Jiggles]

ever see one with a turbo?

I didn't think that any kind of supercharging would work on a 2-stroke. The extra charge should get blown straight out & into the exhaust.

 

[Nerobro]

turbocharging and supercharing works very well on 2 strokes... more on this later ;-) It is lunchtime here.

 

[Nerobro]

You do need to re-engineer a 2 stroke for truely effective supercharging, but turbocharging is a wonderfull and fairly simple thing to do.

Two strokes have a built in supercharger. The crankcase. As the piston goes down it compresses the air, and then when the piston opens the intake port, compressed air shoots into the combustion chamber. The effect is fairly mild but it is there.

Now, if you don;t want to burn oil in with your fuel, you can choose to run a non-crankcase induction two stroke. These tend to be diesels, and very large. Some firetrucks, and many diesel locomotoives are this style engine. They have a dedicated supercharger that provides the boost needed to ensure good induction. These engines are sometimes turbocharged as well.

Supercharging a crankcase induced two stroke can be problematic at best. all engine porting and tuned pipes would be thrown to the wind when you have more than mild supercharging on the induction side. You also increse crankcase pressure and reduce available horsepower. (lower pressure ratio on the top versus the bottom of the piston..)

Turbocharging is different. Because turbochargers increse intake pressure, and exhaust pressure, many of the tuning principals remain the same. However due to higher pressures, tuned pipes change their tune, and you need to make sure whatever tuning system you use is designed for use at the higher pressures.

The most frequently turbochared 2-strokes are on snowmobiles. It seems the 700 and 800 cc engines are the most frequently abused engines

 

[lecroy]

Nero Bro

Some good info. Thanks for posting. I have seen some of the Detroit Diesel 2-strokes with superchargers but never a scavaged port like we all know and love. I never asked about the expansion chambers on the 2-strokes I have seen that were spraying. The RD with the Tom Turner pipes appeared to be untouched. I would think it would be the same problem.

 

[lecroy]

Speaking of 2-stroke turbos....

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=4505167195&category=42608

 

[earlfor]

A turbocharger is simply a class of supercharger. The primary difference is in how they are driven. Turbocharging is ALWAYS more complicated and difficult to install and set up than supercharging.

Earl

You do need to re-engineer a 2 stroke for truely effective supercharging, but turbocharging is a wonderfull and fairly simple thing to do.

 

[Nerobro]

You're right. But a byproduct of a turbocharger is incresed backpressure. This will make the engine behave more like it is at sea level. Versus supercharging which will not increse backpressure. If you ran a superharger on a 2 stroke you would need to time it very very conservatively. At least if you expect to retain any of benifits.

Hmm... Actually. If you just reduced the size of the stingers on the tuned pipes you might be able to compensate. Hmm.... You'd be doing the same thing as with the turbo, effecively running the whole engine at a lower altitiude. I think that needs some experimentation.

 

[Mr. Jiggles]

What does turbocharging usually do to the HP curve on a 2-stroke? Does it make the curve steeper?

Thanks,

Jeff

 

[Nerobro]

That's a very good question Anyone have a dyno chart of a turbocharged 2 stroke?

 

[Mark Harrop]

check it.....

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=4512026610&category=10062

 

[Nerobro]

Interesting, turbocharger after the tuned pipe. 142hp on 350ccs.... Those are some impressive numbers.