Modified LS3 head to LS1 block
Teching In
Joined: Dec 2016
Posts: 29
Likes: 0
From: Arkansas
Here is the heads i was talking about: https://www.summitracing.com/int/parts/nal-88958758 It is 1356$ for pair, and allready CNC ported. Why head ports should be ported again? I know LS3 head ports are not optimal for small bore heads, so what?. First question was does the engine even run, or how crappy the power curve is. Sure there is choke point at intake valve, but let it be there. If i had lots of money, i would buy those heads and test it out. If it outruns ported 243, or equals with aftermarket heads, then test is success. Machine shop guy said it is possible, but he did not mention how profitable it is. He is doing what the customer payed for.
99% of the time, a smaller port, well flowing head, will outperform a larger port. It doesn't even have to flow that many CFM. A head with good velocity in a small port (but large enough to provide enough air to the cylinder) will always outperform a large port. That is why home port jobs often lose power because they are just made bigger, and not better than the original port shape. You will run into this "bigger just to be bigger" effect with those square port heads on a small bore engine. It's just not needed. Look at the size of the ports on a small block head sometime in comparison to any LS head. LS ports, even cathedrals, are huge in comparison to a lot of the sought after factory small block castings.
It's worked for many so far, so don't go crazy with the DIY porting, use quality components, and you should be okay.
It would be most beneficial for the intake valves, the exhaust valves won't really help much but they're often cracked below the valve tip. The main thing is that you have a machinist cut the new valvejob for the larger valves. You don't really want to just put them in with the stock valvejob that was meant for a 2.00" valve.