What's the brand of choice these days? Bumping the compression in an 04 5.3 and can't seem to find any threads discussing it.I'll be using the newer gen IV style rod and stock crank. Thanks.

 

Autotec makes some nice forged pistons that don't break the bank. I have them in my N/A 404. I had to get some funky 4.010" pistons made and they had no problem doing it, and the turn around time was great.

However, if you are keeping it N/A on a 5.3, your most economical solution is to get some Gen IV 4.8/5.3 pistons because they are flattops. You won't have valve reliefs with the GM pistons, so just remember to measure your valve clearances with whatever cam you select.

For reference, I have those pistons with 862 heads on a 5.3 and compression is right at 10.5:1 with GM .051 head gaskets.

 

I failed to mention that I don't have stock cylinder heads. I have some ported/polished/milled 241's that flow very well. I got a great deal on them and pistons are way cheaper than cylinder heads. I'm aiming for closer to 11:1.

 

Do you know how much they were milled?

 

Basically .005 to clean the mating surface. Probably not enough to consider them a true "milled" cylinder head but potentially enough to make a difference if I go with an aggressive cam. This will be a max effort 325. I'm planning on spinning it past 7000 rpm. The heads flow right at 300 @ .600

 

Check out Wiseco PN K0041XS. It has a 6cc dome to get you closer to 11:1, but you're still going to need about a 61cc chamber to get there. You're probably at about 67cc now with those ported 241 heads.

 

Assuming that you are using the OE LS1 head gasket with a 3.910" bore and .051" thickness, with 6cc domed pistons, 64cc combustion chambers, and the pistons coming .005" above deck, you would be right around 10.9:1. 63ccs would put you just over at around 11.07:1.

The rule of thumb is 1cc for every .006" milled off the deck. So, with .005 taken off, you're probably at or just under 66cc. Another .015" would get you to where you want to be. However, you will need to see where your pistons are in relation to the deck at TDC.

 

Why a .051" headgasket and not a .040 (compressed) if he is looking for a max effort motor? I wouldn't leave anything on the table, compression and a good tight quench =more power. PTV becomes a concern but can be checked and dealt with.

 

If it's strictly NA, I'd look at maybe something like the Mahle 4032 forgings. They allow a tighter piston-to-wall clearance for NA applications vs the 2618 forgings. They are not as strong however.

 

You'd be fine with a hypereutectic piston as well. It would allow oyu to run a tighter PTW clearance and run a lighter piston. Saves you some cash as well but if you even think you'll add a power adder down the road just go forged.

 

What are some good hyperteutectic pistons to run besides OEM stuff? Do any of the aftermarket manufacturers also make a hyper piston in the same range of sizes/strokes as the mainstream forged stuff?

 

I was just inputting numbers to give him an idea on what needed to be done to achieve 11.0:1 on a 5.3.

Keeping the same numbers I used before, but switching to a .040 gasket, 66cc chambers would be at ~10.9:1 and 65cc would be ~11.09:1. Again, the major assumption being that the piston comes .005" out of the hole.

 

Keith Black is the only hyper I can think of or maybe whatever Thompson runs in their non-forged rotating assemblies.

Mahle and Autotec have the 4032 forgings which are an upgrade over the hypers.

 

Agree. Why spend the money, time and effort building a max performance short block with cast (Hyper eutectic) pistons? Yes, it's twice the $ to buy forged but worth it. I have seen a few H.E. pistons n performance applications separated at the ring land, tops taken off and it's not a good look. H.E. pistons are for claimer engines or less.