[funtvrk]

HI
I have a pantera 50 that I would like to put a 90 into, what would be the pros and cons of going with a 4 stroke other than a 2 stroke.

Thanks in advance.

[xv-townboy]

Been done before.Not enough power for most people and the rpms for the 4 strokers were hard to re-gear the heli to support proper head speeds.

Cool though..

You Tube

You Tube

You Tube

You Tube

[Cougar429]

As one wanting to convert from electric to nitro on the larger heli, (T600) I think this one has possibilities. The reduction in noise and smoke would definitely be worth it. So far most are reporting a lack of power with their attempts. For my kind of flying, which would be more scale anyway, the lack of wild a$$ed 3-D capability would not be a big problem.

Yes, on that note when you think equivalent size, 4-strokes are less powerful. However I think as with all the other tech, with the number of skilled tinkerers out there this one can be licked effectively.

Maybe I should have kept my YS91AC.

[vinver]

Cooling is an issue with 4-strokes, as there was never a 4-stroke heli engine available, you would need to adapt an airplane engine. Vario had a boxer twin that used a 4-stroke flat twin, but there weren't very common, and expensive. XV, did you notice the horizontal fin on the second video you posted? Only a matter of time before the blades hit that and send it into the netherworld!
I had a Century Schweizer with the Phoenix conversion with 4-stroke, but never had a chance to fly it. Bought it used as a problem heli with tuning issues, sold it the same way.
Vince

[Max]

I dont recommend going to 4 stroke.

Why?

because for the ones I have flown using 4 stroke power, you have ONE big problem with 4 strokes: They backfire(Kick-back)

On an airplane, its not so bad. It results in the motor going backwards (on start-up) or in the air- it kicks the prop off. Mind you , with the double nuts used on today's 4 strokes, kicking off the prop doesn't happen so much, but nevertheless, the kick-backs occur.

Why is it a problem for 4 strokes? Because that kick-back will result in a stripped primary gear. I can't tell you how many times I have seen this happen. Especially when in the air- the kickback occurs and BZZZZzzzz! there goes your drive gear.. (NOT AGAIN!!!). On the ground during start-up, it happens more frequently than in the air, but just as upsetting all the same.

When it happens to you a couple of time over the course of 1 summer, you learn to hate 4 strokes in helis very fast.

JMO.

[Cougar429]

Max, from my own experience kick backs only occur when the motor is run lean. My Saitos are particularly prone to this and until I learned their tuning lost a few Higgleys and legacy lock systems.

[Max]

I know. That is part of the problem with 4Strokes on helis. Tuning is not as easy as we do for airplanes. It is a slow and tedious process; Adjust and hover...Adjust and hover. Along the way, as you creep up on the tuning of the 4-stroke heli, one small adjustment suddenly makes your motor kick-back, with very predictable and costly results.

[funtvrk]

WOW

I did not know that, I will no longer be going with a 4 stroke and go with a 2.

Thanks so much.
Richard