piston and rod mod
07-31-2010, 09:50 PM
#1
piston and rod mod
here are some pic of my piston and rod not done all the way. still need to even my piston and polish every thing up. tell me what you think bad or good if bad tell me y just dont say crap.
07-31-2010, 11:58 PM
#3
iam not done with it yet. but i did not cut the center of the rod like some people do. this is a sirio rod and piston so the rod is super strong and the piston is cnc. no jap crap here.
08-01-2010, 01:14 AM
#4
If it could be made smaller within a safe use then it would be smaller.....
By the way, the rod does flex to take out the peak force, if the rod is made from a very stif material it would shatter into 1000 pieces within 10 minutes. Been there, done that......
Looking at the surface you have to polish a lot, for sure sharp edges are the places where it will crack first and that will also go for the piston.
08-01-2010, 02:53 AM
#6
Looking at your cuts and where you have them I'd have to say that the most you did to your crank was lighten it and put it out of balance. The rod is another story. I'm also no pro, but I think you may have gone too far in knife edging the rod. At the RPM's these motors pull, that's a bit much for the material we use and what we put our motors through.
I'm not sure why we would want to really modify our motors nowadays? Back in the 90's, we used to cut cranks and sleeves for more flow and power back then. But now, the motors are so overpowered I'm not sure why you might want to risk the motor to get a little more power. Before cranks and sleeves were plain with no turbo cuts or porting cuts which is why we did it back then. I've run modified's from EB mods, RB mods, CEO, Hot Mods, OS Speeds, and JP's and while they are great motors it's hard to justify these costs to newer racers who need more track time in order to use the power.
Good luck with your motor and I hope you will still have a reliable motor when you're done.
08-01-2010, 07:50 AM
#8
if you think i cut to much look at this pic. this is a onroad rod it is thick and this more has a smaller piston than most .21 i think the rod might belonger to but the crank is longstorkeand being long stork it will have a little less stress on the hole motor.
08-01-2010, 08:20 AM
#9
Tech Addict
iTrader: (14)
You went this far, run it. No reason for all that work and not seeing how it performs, who knows, maybe it's not as bad as it could be. As Roelof said, you need to polish the hell out of that rod. You need to round off all of the pointy surfaces, anything pointy and not rounded off is a stress spot waiting to happen.
08-01-2010, 08:40 AM
#10
One rod isn't the other.... The material is making the specs and if a rod is much thicker then you can imagine it is made from a less stronger material.....
08-01-2010, 12:34 PM
#12
Yep, ony tiny change at the crankshaft timing will do a lot more than all tose fancy cuts.....
08-01-2010, 01:01 PM
#13
This is 100% true all I was saying is that it looks like he was just cutting and didn't have a certain goal eg more overall power,more bottom, more fuel eco or more top. I will say this you have way more gull than me because I would never cut my engine at least not to that extent. The most i've done is mod an old side exhaust opening so it would match the port on the engine(increased flow). I have toyed with the idea of doing small knifing on the sleeve but I haven't found a motor I am comfortable trying it on. Anyway good luck with your mod I hope it works out for ya!
08-01-2010, 01:21 PM
#14
It doesn't really matter what "we" think. The only thing that matters is, when you re-assemble your mill, does it run better or worse than it did before?
The fact that it looks like it was vandalized and mutilated is irrelevant, but humorous from a story-telling perspective
