.40 pipe on a .60 engine?

[Got Speed]

I have a K & B .40 with a pipe on it and was wondering if I could put it on my Magnum .61?

[phuffstatler]

I wonder if it will have enough volume to let the .60 breathe properly? I know the whole trick to pipes is to have a pressure point at an exact spot to let the engine run at it's best, at the RPM range you choose. Hum... I'd be interested to know about this one as well. There's a nice little formula for this sort of thing, but I've forgotten it (old age..?)

I DO know you'll need a new header to fit your Magnum engine. The K&B won't fit it.

I remember my YS .60 short stroke on a pattern plane (Joker) had a glow plug to high point on pipe measurement of 16.5 inches ( I think) and my OS 46 on my Patriot it was like 14.5 inches. So there were some definite changes there. Different kinds of flyng and props can dictate pipe choices too. Oh wait, the YS was rear exhaust too. Shucks, now I can't be sure at all... SIGH! :rolleyes:

And after all the melarkey above, I still can't give you an answer!!!

:D

best of luck,
phil in austin

[Got Speed]

When I get around to trying it I will let you know how it goes.

[Dave Robelen]

Hi Gotspeed,
You can expect that the .40 size pipe will choke the .61 down. The resonance is based on a combination of cylinder volume, rpms, and temperature. You can get 2 out of 3, but that is not quite enough. There is a paperback book available thru bookstores called the "Two stroke tuners handbook" written by Gordon Jennings. It was originally targeted at racing motorcycles, but the formulas all apply to our stuff, and it really is well written.
Regards, dave

[Got Speed]

That's what I though because I know you can't put a .15 pipe on a .21 car engine. I was wondering because I saw a pipe listed for a .40 or a .60 engine and didn't think that was possible. Does the book have a yellow cover?

[Dave Robelen]

Hi,
Mine has a light blue cover, but that could change with different print runs.
Regards, Dave

[Got Speed]

Ok. I saw a really nice two stroke engine book at my hobby store. I was wondernig if it was the same one.