Originally Posted by
wmazz
Do some engine tuners avoid the break-in process by hand lapping their pistons?
Is it possible to buy replacement pistons, instead of matched sets, or pinching a cylinder.
I would love to see Dykes rings to be used as a replacement part.
There are reasonable priced 37cc single cylinder 4-strokes available, that could be fitted for
1/5th scale. Especially if the rule committees would adopt the 2:1 displacement rules for 4
strokes like the AMA did.
wingracer, or anyone:
As I understand it, the basic strategy for tuning a nitro rc is to set the clutch up to take advantage
of the acceleration on the front side of the curve, in order to slingshot you through the backside of
the curve. Use 30% nitro and relatively hot glow plugs to maximize that acceleration, and through
good tuning you strive for the most controllable, drivable combination possible?
Why can't I just make the most power possible and gear it right? Tune it to be the most controllable,
drivable combination possible, without detuning the engine.
I know I am not the first Dumb mule to want to this but can you tell me why this didn't work?
I have done it before, In motorcycle speedway racing. I took an overpowered European long track
engine, and found a solution that made it so drivable and trackable on the short tracks in the USA.
The bike got great traction, and even with worn out tires.
My brother was a top 10 speedway pro, and 4 of the top 5 riders had the same engine, but they
used it as a back-up bike because they couldn't get it to hook up. I know this may seem to be
apples and oranges, but the principals for making an engine trackable is the same.
Bill Mazz
Hand lapping? I'm sure there may be some tuners/Mfg.'s that do that to a point, but a brake in is still needed. Maybe more so for everything else in the engine. I think most of the high end engines run a set for replacement pistons ans sleeves. Again there's a reason for that. Having rings to replace instead of the P&S as a set would help, but at what cost or gain. I'm sure rings have been tried in car/truck engines at one point, but I do not know how well that worked or didn't work. If I had to guess, there may be a point where you simply couldn't make the needed rings small enough and with the consistant tight tolorances needed. Say a .12 engine or smaller.
On the 4 stroke side, a 2:1 displacement could help, but at what cost? That's seems to be one of the big catches. Bigger the displacement, the more weight that gets added to the chassis. At some point, it's going to be too much. The bigger catch is that they don't have the high rev RPM's like the current engines do, and with only a single gear tranny being used, there's only so far you could go before something has to give.