has anyone used gen5 pistons in a gen3 block with gen4 rods before ? thanks

 

Why would you? Gen III and IV parts are easy enough to get, and you KNOW they work....

 

true, just have the parts laying around and seeing if anyone had build something like that.

 

I'd like to do the same to build a much higher comp gen4 engine cheap. I'm not sure if the new pistons clear the counter weights on the gen4 crank though. And if they don't Can I simply run gen V pistons on a gen4 rod? I'm shooting for a budget 13:1+ on e85

 

So the valves are reversed in the Gen 5’s. If your looking at using a Gen 4 head, the Gen 5 pistons won’t physically work, because the valve pockets are reversed, for the Gen 5 heads.

 

Would that not depend on the cam and lift you ran?

Or maybe even flipping the piston 180*? They are centered rods, are they not?

appreciate the input!

 

No sir. Cam has nothing to do with it. You can’t flip the piston 180…it just will not work physically. That valve pocket on those domes in the pic…that is the exhaust valve pocket, or relief. In a Gen5 engine the exhaust valve is on the left. In a Gen4 engine, it’s on the right. You have to run a Gen5 head with those pistons.

 

Really appreciate the input! So not even worth tossing one piston and checking what the PTV would be in your opinion? Do we know how far the dome sticks out above the deck? I could run a .5xx lift cam

 

He basically said- Don't use them....

 

That's what they said about stock pistons and boost 20 years ago too... look where we are now. They are relatively new is all. I'd like to know if anyone has tried and what the PTV clearance actually is.

If one could simply toss these in with a low lift cam and shaved heads to get 13:1++ on E85 it'd be worth it IMO. Thought it was worth looking into seriously is all. I don't have a piston to test. But I can get L83 long blocks pretty cheap here.

 

What you said about 20 years ago, and your present situation now, don't even relate. You would have to do so much monkeying around to make the Gen V pistons to work, it's not worth it.
Trying to make something work just because you have it on hand isn't always practical or even sensible.

 

That's your opinion and you are welcome to it. I don't agree.

 

Is there enough meat it the piston top to fly cut it for the reversed valves?

 

Then try it, and be sure to let us know how it turns out.

 

Will do. I've cut as much as .170 on the factory flat top gen4 pistons. I'm sure a L83 could be cut the same, but likely that much will not be needed.

I just cut .100 off a 706 head and fly cut the pistons as needed for over 13:1 on an SBE 5.3.

I needed to cut very little for proper PTV on my 13.4:1 SBE 5.3 after milling the heads .100.

 

I have Diamond pistons and they have two fly cuts. They have a pic on their website.
I think my cam is 590/620 lift, and putting the heads on, I forgot the locator "pin" and cranked the engine over by hand and the valve hit the piston. Cost me a head gasket for forgetting that. The L83 heads have a different valve angle too. If you have the equipment, give it a try.