I bought my car used and it came with these SLP/AFR 225 Big bore heads but my car is only a stock bottom end 346. I swapped out the cam and put the one in my sig in. Im still down on power a bit so I am going to sell these heads since they are way too much for my heavy car. I havent been in the LS1 Game for quite a while so I dont know whats the latest and greatest ported heads for a 346 on a budget.

 

Any track times? I realize that head is optimal on a 4.0" bore but it should still work very well on a 346 ci 3.9" bore motor. Hell I have seen it.....I am guessing you have other issues....

 

12.9 @110

 

Yeah that is a little high. The weird thing is that is enough HP to run mid twelves but your trap is about right for that power.....

EDIT: How much stall you running????

 

Stock stall. Everything else is good with the car.

 

the stock stall is hurting your et. stock gears?.is it tuned for your current combo?

 

Its tuned for my combo, 3.42 gears, stock stall. I know the converter is hurting my et. But my car is down on power. I should be trapping higher and putting more power down.

Basicly some mild worked stock casting heads will give me more or at the very least same power as what I have now allowing me to also sell my ls6 intake and get a FAST setup at almost no cost or keep that manifold and use the diffrence in price to offset the cost of a new converter.

 

Man those heads can make good power on a 346 car. I am making 434rwhp with 220cc heads on a slightly bigger cam so I don't think the extra 5cc is hurting you that much. With a ported FAST 90, 85mm TB and bigger lid I think i can get to 450 and a little change.

I would PM Tony Mamo or call him and get his thoughts. He is a great guy and will be more than happy give his opinion... I promise you it is not heads and something else. If the PR's are to long you could have valves hanging open costing you power. Did the graph indicate valve float? Was the PCM reading false knock and pulling timing? What is your total timing IIRC those heads are so efficient they like about 26* but I could be wrong there. You may have one cylinder misfiring and that is 50hp+ right there. Could be other things too but honestly it is not mismatched heads. Your torque is low too. Mine makes more than that at 3500 rpm... If you get rid of those heads I think there will be a day you regret it...

 

There are 2 versions of the 225 heads, small bore and big bore, part of my combustion chamber is shrouded by the bore. Im trying to find everything out on them but the tune is spot on, timing was around 27 iirc, pushrods were measured, no float, good compression all cylinders. Im going to go through and check everything before I sell the heads first.