A question for the engine gurus

Some time ago I read about `Turbo Grooves' in crankshafts. I am fairly sure this is a modification for speed rather than stunt, but can anyone tell me what they are? And are they for engines with ball race supported crankshafts or plain bearing (bushing) motors?

Are you talking about a small spiral oil groove around the outside of the crank from the intake to the front bearing? Or scallopping the inside of the crank to where it opens to the bottom of the piston?

Turbo Everything has become quite the marketing B.S. in RC cars.

Turbo heads, turbo cranks, turbo plugs, turbo porting, on and on.

Ignore it. There is no application for this "technology" in CL Stunt engines. In fact, there is only little justification for it in the RC car world even if they are coming up with very, very high specific output engines.

>Turbo Everything has become quite the marketing B.S. in RC
>cars.
>
>Turbo heads, turbo cranks, turbo plugs, turbo porting, on
>and on.
>
>Ignore it. There is no application for this "technology" in
>CL Stunt engines. In fact, there is only little
>justification for it in the RC car world even if they are
>coming up with very, very high specific output engines.
>
>Dan

Put a turbo on it.....It'll go faster..... Not what we need for stunt.....Some of the K&B outboard engines(3.5cc pros and 7.5 redheads) have the oil grooves in the cranks to promote longer bearing life to the top bearing. I certainly wouldn't waste any time trying to modify stunt engines. Proper piston to cylinder fit is the key to any engine as far as power is concerned.

".....Some of the K&B outboard engines(3.5cc pros
>and 7.5 redheads) have the oil grooves in the cranks to
>promote longer bearing life to the top bearing. "

This is also typical, if not standard, on helichopper engines. It would probably make the engine puke a lot of raw fuel out the front bearing, ruining the paint and increasing fuel consumption considerably. While the rest of the engine might be just fine for our use, this feature would need to be deleted. JB Weld to the rescue.
Steve

And lets not forget "Turbo ketchup" wich incidently is a vegetable! Paul

>And lets not forget "Turbo ketchup" wich incidently is a vegetable! Paul

Hmmm, perhaps not. I think a tomato vine is actually classified as a tree, thus making it a fruit. True?

Dan,

I saw an RC car about a year ago somewhere on the net that an actual working turbo on it. It was so cool. Have you heard of this or seen it? I cant seem to find anything about it now.

some of the F2D engines are using grooves cut in the edges of the whole in the crank disc to make sure the fuel coming down the crank is fully atomized. Apparently the idea came from the speed circles. Some of them also have used notches or dimples cut into the inner edge of the squish band in the head. As least, as Dirt's buddy Ralph says, "at least it doesn't seem to hurt anything".

Nothing beats the right piston and liner fit. Not something that is easy to do at home.

Take a look at the top of page 41 in March 2004 Flying models.You will see a picture of a turbo notch in the back of the crank on a Zorro combat engine.Hope this helps clear up your question.

Thanks guys for all the information (and suggestions). I wasn't planning to start inflicting any stunt engines with these adjustments, just trying to satisfy my curiosity. Its about all I have working these days.

Dan,
I saw an RC car about a year ago somewhere on the net that an actual working turbo on it. It was so cool. Have you heard of this or seen it? I cant seem to find anything about it now.

Doug Moon

Doug,

Nope, didn't see it, nor have I heard of it. Sounds like the car might be a very big handful to drive, what with turbo lag.

Duck's comments about spiral grooves in the cranks of outboard engines is probably true, what with the "front" bearing located on top in this application. However, a common trick during my time in RC cars was to run the spiral such that it pulled fuel away from the front bearing. Better mileage was the argument, but back then we were doing a lot of things that later on proved totally bogus.

Not mentioned previously, although indirectly, is a reflection of Phil's comment, this echoing Ralph. It has been my experience in the RC car world and in others, RC Pattern is a good example, that modifying an existing product such that it is merely different is sometimes good enough. It does not have to be better.

Remember, other than commodities, things sell in our world for three reasons only: 1) It is different; 2) It is cheaper; 3) It is new. Just getting one is good enough in a lot of cases. Nailing two is terrific. Garnering all three makes it a winner. Assuming good marketing. Which the guys pushing Beta video tape systems obviously did not have, just as one example.

Racing Stripes. Add racing stripes to your model. They add 5 mph, at least on my last speeding ticket....