ORIGINAL: XJet
ORIGINAL: Rcpilot
4-stroke? [sm=lol.gif] Who needs 'em? Not me. They are expensive. They have more moving parts. They aren't as powerful as a 2-stroke. They need more maintenance. Shall I continue...............? [sm=lol.gif]
It depends very much on what you fly and your flying style as to whether 4-strokes are for you.
Yes, they are expensive. Yes they have more moving parts but, surprisingly, they are usually cheaper to fix and less likely to get damaged in a crash than their 2-stroke cousins. Cubic-inch for cubic-inch you are right when you say that 2-strokes are more powerful but it might surprise you to know that weight-for-weight, quite a few 4-strokes are actually *more* powerful than their 2-stroke cousins.
Just compare a 22oz Saito 100 with the equivalent 22-oz 2-stroke and you'll see what I mean. And the YS 4-strokes are stronger again!
As for needing "more maintenance", that also is true but you make it sound like they require a *lot* of maintenance, which they don't.
My Saitos get a valve-clearance *check* at the start of each flying season and for the last two seasons they didn't even need adjusting. That's it full stop. No other "maintenance" required and you can check the tappet-clearances in about three minutes so it's not exactly a bgi overhead for the entire season's flying.
And let's face it, the fact that 4-strokes are far more tolerant of mixture settings than 2-strokes means most people spend far more than 3-minutes tweaking the needles of their 2-strokes every weekend while my 4-strokes don't need to be touched from one year to another.
4-strokes are for guys who like to tinker.
Well in my case, 4-strokes are for guys who like to fly. My Saitos really have been "fit and forget" engines. They start instantly *every* time, don't deadstick, are very tolerant of different mixture settings and prop sizes. There's no tinkering required at all.
Don't give me that horse poop about "more torque" for 3D. I got 40 size 3D planes with 2-stroke engines that do perfectly fine.
But do you actually fly hardcore "down on the deck" 3D?
If you don't then you probably don't really appreciate why 4-strokes excel in this area.
Lots of folks think "3D" is all about flips, loops, hovering at 30 feet and a bit of knife-edge. Sorry, that's *not* hardcore 3D.
"4-strokes will rev quicker because of the low end torque " blah blah blah blah
Really? Has anyone ever put a 14-6 prop on a Saito 91 AND a ST .90 and used a stop watch to see which one hits full RPM faster? I didn't think so..........
Once again, you're comparing cu-in with cu-in when the most valid comparison is weight for weight.
Take a any 22-oz 2-stroke and compare the time it takes to hit full RPMs with a Saito 100 when they're both turning a 15x6 prop. THEN you'll see why 4-strokes have this reputation.
And if you note carefully, most models say something like (0.40-0.50 2-stroke, 0.65-0.82 4-stroke) so even the kit/ARF makers acknowledge that it's not about direct cu-in for cu-in substitutions.
Give me a 2-stroke ANY DAY. [8D]
I'll take 2-stroke, 4-stroke jet and wankel they're all good!