I'm looking for some flat-top pistons for a budget 5.3 build. Going to have 612 lift and 236/246 duration so I've been advised to get pistons with a valve relief.

Found these on ebay ($100 for a whole set !), but I don't understand the relief .. why aren't they on the same side of the piston ? I'm sure this is a dumb question but ... there it is

 

Ok so I think I figured it out .. they're only concerned with the INTAKE valve, and the intake valve switches ends from the port to the starboard side .. have I gotten that right ?

 

Nope. The heads are identical from side to side. The piston has no idea which side it's on.

 

You're right that the heads are identical but when you rotate them 180 degrees the valves are rotated with them.
The intake valves are closer to the front on the driver side and the exhaust are closer to the front on the passenger side.
I'm not certain if that is why the reliefs in the pistons are done that way but the op's theory makes sense to me.

 

You are correct, but the relief on those pistons is for the exhaust valve.

 

It really doesn't matter. I wouldn't buy a complete set for $100. They are probably just plastic pistons with a chrome coating. You're better off buying from a reputable dealer located here in the U.S.

 

that seems backward ..

 

Based on the picture those reliefs are aligned with the exhaust valve.

 

these sealed power pistons are the same :

 

Also .. just to confirm .. If I put a piston like that (flat top piston with valve reliefs) on the stock 5.3 rods and crank, I won't need to balance the rotating assembly, right ?

 

I would re-balance the rotating assembly. The sealed power pistons might weight differently than the stock ones you are replacing, so It will through it off.

 

Exhaust valve is on the right side of the chamber for all LS engines. The current LT series engines is the opposite. GM flipped it around for performance with the LT engines.

 

Flea-bay specials:
The plastic pistons with chrome coat are are $125
Paper mache pistons with silver paint are a $100

The bitterness taste of low quality junk remains long after the sweet taste of a low price deal has disappeared. That's especially true with critical parts.

I agree with Utinator, I'd get a set from a reputable dealer. Summit & WS6 Store have quality sets for like ~$300 to $400 with quality ring sets.

 

Why spend triple the money on $400 pistons when $125.00 bone-stock pistons easily cover my requirements ? Seems the overage would be better spent on trunion kits and higher quality timing chains.

I guess what I *really* need to do is see if I can get by with actual OEM 4.8 pistons and clear the valves at .612 236/246 110, and run them if so. More mysteries to solve ... also, I'm running stock 706 / 862 heads with small valves so that'll help some I'd imagine.

BTW, this isn't meant to challenge .. you clearly have the experience here I'm just looking for a cheap motor in the 450-475 HP range I can go make a bunch of laps on at low cost.

 

Hope saving a couple hundred bucks on very cheap quality chinese pistons doesn't ruin your entire shortblock in short time. I myself wouldn't use them if I were wanting my motor to last a decent amount of time. I'd rather flycut factory stock pistons myself in lieu of using those if I were on that tight of a budget. Either way, good luck to ya.

 

You have been warned. Enjoy the build

 

Cheap to get to 450 HP, is about 5-10 grand. I spent at least 5 grand on Heads/Cam/Intake and Exhaust with all their supporting parts. And I am still probably not even at 450 at the wheels yet even after tuning. Its probably there at the crank. The only thing I haven't touched is the shortblock internals. Im still running on a stock t-56 and rear end. Im expecting those to blow up soon. If your looking for cheap, your in the wrong ballgame. Its unfortunate but true and its something we all learn eventually. We've all tried to cut costs using inferior parts but end up having to replace them in no time and it ends up costing us more time and money. Don't skimp out on such an important integral piece of your engine or there will be consequences to be had down the line.
Talk to whoever gave you a recommendation of getting valve relief pistons and ask them what pistons to buy.

 

Let's put it more directly- WHEN those pistons go (and they WILL) the carnage will include the block and rotating assembly. You might salvage the front cover, valley cover, oil pan(MAYBE), rear cover, and intake. This should not be a "Let's see what happens" opportunity, unless you have a bottomless wallet.

 

I noticed they dont post a brand and also that they Dont include snap rings or lock rings.
If your using a Floating pin rod, You will need those to retain the pin.

The fact they dont include those has me concerend. If there not machined the same as the factory they minght hold if you use a factory style lock.

I see another set of chinese pistons for $90and they even include the locks.

There is a set of NPR pistons that include the locks and the rings for $200

 

It's a fair question here's my view based on 35+ plus years of hot rodding cars.

Typically internal engine parts with the bottom barrel price have bottom barrel quality. There's a thread on here about was a $275 4 inch LS stroker crank that seemed like a deal. It was so badly out of balance it only took $500 to get the thing balanced. So the poor guy had $775 in a weak cast 4 inch crank. A Callies Compstar costs $775 and often you can buy a Callies balanced. The bargain crank had an narrow journal that required expensive rods or more special machine work to narrow a standard rod. This is typical of the cheapest parts.

Manufacturing tolerance tends to be sloppy on the cheapest parts. Getting better ring seal is easier if the pistons are held to a tight tolerance and actually have the correct dimensions.

The stock LS piston is one of the weaker parts of a stock engine. In hard performance use stuff gets hot and sometimes the ringland butts. That pushes the piston crown up and instant disaster. I won't reuse a used stock piston because it's a fairly weak part to start with. Cylinder #7 and #8 can be brutal on stock pistons. My first junkyard LS1 #7 failed leak down. We tore it apart and the stock replacement piston was toast in #7.

If your car is running laps your engine will generate a lot of heat. A perfect fitting piston (precision) that runs the correct tight to cylinder wall clearance will transfer heat better and run cooler that a marginal fitting slug. There are a lot of excellent pistons, rings & locks available for the LS at a reasonable price of $400 or so. I suggest taking advantage of that and building a better high quality engine that lasts for a good while.

FWIW - Wiseco is my pet favorite piston company. They make a lot of pistons for other folks under various brand names. It very possible to have high quality parts at a reasonable price. Likewise, Mahle's an excellent contender as well.

If $400 to $500 for a set of good pistons is too expensive now save to get the parts. It took me a year and a half to plan, budget, get parts and finally get a 416 completed by Norris Motorsports with Callies Compstar forged crank, Callies Compstar rods & Wiseco pistons. That was one of my faster engine projects

Cheap Cam for Sale - sweet price, no warranty, no refund, as is
If you want to save on a cam I've got ~238/244 lift is ~.620 is on 114 LSA out of engine that only had 700 miles on it when car wash stolen and engine destroyed with a missed shift. CCsn share specs if your interested. Will sell you the cam cheap if you want it for $100, might help free up some $$$ for better pistons. Cam is as is, no warranty or assurance or refunds. Can end pictures if you want to see it etc.