boring out nitro engines

erock87 · 09-17-2004, 05:08 PM

i have an os cv.12 i was wondering if a .15 piston and sleeve would fit directly into it? If not can i bore it out to make it fit, if i can bore it out what does it require me doing to do it?

thanks erik

jamiekulhanek · 09-17-2004, 06:08 PM

you mean bore out the alloy block?? Why not just buy a new .15 block?

erock87 · 09-17-2004, 06:15 PM

the whole point of thsi is not to buy a new motor but just to make the 15 fit in the 12 motor to last and run for a solid 10 min for about 4 more races.

AE Racer · 09-17-2004, 07:05 PM

No, and no you cant bore it out. There is pretty much no chance that the ports of the .15 sleeve will line up correctly and if you tryed to bore it out you would need incredibly accurate equiment which I doubt you have.

erock87 · 09-17-2004, 07:21 PM

what if i just used the 15 piston in the 12 sleeve and drilled out the 12 sleeve?

ccm399 · 09-17-2004, 07:39 PM

First, sleeves are NOT drilled they are bored then honed. After those two operations are complete the bore has to have a hard chrome applied to it. I build full size race engines for a living and I don't even have access to the machines required to perform these types of operations. ( well at least not small enough ) I think you would be way better off getting your old sleeve pinched. Just look up OS rocket on the web he only charges around $25 and you can normally get good life out of the engine after he does his thing. Just my .02

Scott Fisher · 09-17-2004, 08:47 PM

Not only all of that stuff that has been mentioned, but the sleeves are smaller at the top than the bottom.

If you notice, there are no rings on these engines like 4-strokes. The seal between the piston and the sleeve is made because the sleeve is tapered to be smaller at the top than the bottom.

Bottom line... Don't bore anything.

beetlebz · 09-17-2004, 10:18 PM

maybe its bad advice, but if it only needs to be run 4 more times for 10 mins at a time, cant you just lean it out for more power? who cares if it cooks if its only a quick fix?

jamiekulhanek · 09-17-2004, 11:07 PM

How exactly does "pinching" work?

jamiekulhanek · 09-17-2004, 11:14 PM

Dude the .15 Crankcase and the .12 Crankcase are identical, except inside.

So you could just put a .15 crankcase and piston/cylinder on it..in theory that should work, but the head might not work.

I can see what your doing....cheating is bad

erock87 · 09-18-2004, 07:16 AM

i am not cheating because the class is small block monster truck. also i could fit the 15 sleeve and piston into the 12 crankcase w/o any modification and it will run good?

I can't just lean it out for more power because the old piston and sleeve and very bad and the motor will not continuously run for 10 full min, it stalls around 5min

jamiekulhanek · 09-18-2004, 01:53 PM

I seriously doubt that it's gonna work, just run it for the next 4 races, its better than ruining your engine doing something you're not sure of....

If it's worn out you can refurbish it with a Duratrax ABC piston and liner kit for $19.99 (genuine OS ABN $50) and an OS conrod for about $12. Provided the bearings are ok. But if the bearings, piston & sleeve, conrod bushings are all worn out, your looking at $60-$90 for a complete rebuild....so its best to just get a whole new engine....