joedude02

Just like the title states. What is the largest intake valve that will fit a 243 style head with the appropriate seats? This is for a LS3 stock bore of 4.065" short block that I got a sick deal on I couldn't walk away from. Already running FAST 102mm setup and have 225cc CNC heads. I just wanna know if it's even possible to make these heads flow enough to support 700rwhp with more port work.

KCS

iTrader: (20)

You're limited by the 1.91" valve spacing, so 2.16" is about the biggest I would go without moving things around.

joedude02

That's awesome news. Thanks!

studderin

iTrader: (28)

on the stock seat you can go, 2.05 is about max I would run for someone. I haven't cut anything bigger so see how it fits or holds up. 1.883 is the most throat Ive ran on a stock seat, for a VJ to fit it. With that bore you can go bigger, the casting will hold the bowl. So you can change to more seat to work with, But like KCS said you run into packaging all that. your going to work backwards to get that hp number, I would use what rpm you want to turn it, then what intake you need for that, and size the head for that, on your engine size. The fast will be 6500-6700 max, you can pull it to 7500 but it falls, you can do some work on it to help. Be careful on the ext bowl going big,the casting is thin behind the guild were the stock cutter marks are. But you can still get a port to fit going to a 1.57 valve. what casting is it when you say 243 style? if your looking to do a setup for good power like this, I noticed some 243/799s are diffrent how the port mold fits the head. The way the stock VJ fits with the underbite or overbite on the casting, You can try to use that for what I want to do with your port, finding a casting to use.

R6cowboy

iTrader: (3)

OP, 700rwhp NA? You really might want to consider a different set of heads if you're serious about that kind of goal. 243s are likely not enough cylinder head no matter how much work done to them.

studderin

iTrader: (28)

243 will do it, there is better stuff out there too. I dont think you could with a fast, with that stuff. You need a big engine with a normal ported fast.

MrPZProductions

not to thread jack here but does anyone know the same info for 862 heads? Need to know biggest valve (was thinking 2.0") for a 4.8 with 862's going with the BTR custom ground turbo cam with their pushrods and titanium retainers- thanks

KCS

iTrader: (20)

The bore is going to limit you on this. 2.00" would work fine, and you could probably even fit a 2.02".

matt k

Ai heads with 2.08 on my 408.