Summit racing pistons

[usaf_daddy]

I'm looking at the summit racing website they show two different part numbers for the l20b... Has anyone purchased the silvolite pistons if so are they any good? and what part number? It's for my l20b daily driver and maybe some weekend fun. Any suggestions?

[ggzilla]

Silvolite cast are just ordinary pistons. Unless they have a forged unit for extreme racing. You can order forged pistons from Arias and other piston makers about $100 each.

 

Otherwise just get normal standard pistons. What's wrong with the ones in your engine now? Pistons are not normally replaced as part of engine overhaul.

[usaf_daddy]

Got it from a guy that ran it for about 8000 mi on a rebuild, then pulled it for a ka swap. He put it in his back yard for a winter uncovered got water into the #4 cylinder so it had some water damage. Other than that it all looks good.

[ggzilla]

Unless it has corroded the aluminum, just clean it up and fit new rings. That means using a gap cleaner on the dirty piston. I'm guessing the rings are rusty ...

[EricJB]

Summit has Silvolite and Speed pro, as far as cast/ hyperutectic. Most opinions I have heard, is more favorably towards Speed pro. I have 89mm KA Silvolites in my drag truck. Even in an L20 block filled with grout and bored .160 over, I rev it to 7k every shift and have had no trouble. (knock on wood) I have heard the KB/ Silvolite hypers are junk.

Did the piston or bore on #4 get water damage?.

[datzenmike]

The deciding factor here is the cylinder condition and wear. Clean the cylinder and measure the diameter at two places 90 degrees to each other about 1/2" down then 1 inch below that and again 1 inch below that. You now have an idea or the previous piston ring wear on the cylinder and how much taper there is, if it's now oval, and how much the piston to cylinder bore side clearance is. Factory side clearance is critical to good sealing in the combustion pressures. A worn cylinder will mean the ring end gaps are too wide also. If in doubt, get the next oversize and have the block bored to fit them.

[wayno]

I'm just throwing this out there, since it only has 8000 miles on it and likely doesn't have a lot of wear, keeping in mind that almost everyone underestimates the mileage ect. when selling something.

Is there pitting/damage in #4 cylinder?

I bought a fresh rebuilt U20 that had also sat outside at some point, and yes I am saying that this engine was bored with new everything inside it and sat inside/outside for 20 years, I cannot remember which cylinder had major rust issues, but 2 out of the four had water in them, one was not bad and needed no more than re-honing, the other had giant pits in the side middle of the cylinder, what I did was have a machine shop bore and sleeve that cylinder, it runs great.

This would be the "throwing it out there" part, if there isn't much wear but major rust issues with one cylinder, can one sleeve the bad cylinder to match the piston, re-ring everything and slap it back together?

[usaf_daddy]

The water damage was bad after I pulled the head I filled the cylinder with PB and let it sit for a few days still had to pound the piston out with a block of wood and a hammer. I took a ball hone to it just to see if I could remove the rust build up that made it better but not enough to make me feel comfortable running it without a trip to the machine shop plus I don't think I did the top of that piston any good by pounding on it. I did find that some water made it into the oiling system I pulled the slugs at both ends of the block and cleaned the oil passages with pipe cleaners wanted to check the passages on the crank any ideas on how to do that?

[Stoffregen Motorsports]

Unless it has corroded the aluminum, just clean it up and fit new rings. That means using a gap cleaner on the dirty piston. I'm guessing the rings are rusty ...

 

If the rings are rusted to the bore then the bore will be trashed too. If you just throw in a set of rings, the rusted section of the bore will wipe out the rings. Even after you clean up the bore, you can feel and measure the divets left by the rust. That slight imperfection acts like a file on the rings and chips away at them every time they pass by. If it's not too bad, you could get away with it, but it's a crap shoot.

[Stoffregen Motorsports]

if there isn't much wear but major rust issues with one cylinder, can one sleeve the bad cylinder to match the piston, re-ring everything and slap it back together?

 

Yes you can, but that would fall under the "repair" type of engine building. Ideally they would all be sleeved or not at all.