no doubt alum heads are superior.
I do wonder if those "fully ported" iron heads had the vanes untouched, finned or removed and what size valves were used.
I also think a big part of why alum swaps are so beneficial is you get to get away from the crappy mpfi intake. I've read about some iron head setups who swapped to the edelbrock performer carb intake and put down decent numbers.
I also think a big part of why alum swaps are so beneficial is you get to get away from the crappy mpfi intake. I've read about some iron head setups who swapped to the edelbrock performer carb intake and put down decent numbers.
yes the intake helps greatly but the main gain is just the heads. Their d ported exhaust runners, larger cc runners, better combustion chamber. It's just a overall better design. Cfm flow is greater no matter what you do to the iron. Just Imagine how much the large port gen 3 will flow with some solid porting. GM head design in v6 and v8 changed dramatically in the late 90s. Wow did they get better. But I'll stop hijacking the ops thread. Sorry.
yes the intake helps greatly but the main gain is just the heads. Their d ported exhaust runners, larger cc runners, better combustion chamber. It's just a overall better design. Cfm flow is greater no matter what you do to the iron. Just Imagine how much the large port gen 3 will flow with some solid porting. GM head design in v6 and v8 changed dramatically in the late 90s. Wow did they get better. But I'll stop hijacking the ops thread. Sorry.
Not hijacking at all. I enjoy the discussion. I have some time off from work the next few days and i'm going to work on gasket matching these heads (leaving the floors alone) and I'll probably knock the vanes out too. I'll post after pics if it will let me by then (still having trouble with that) and also, when the engine is finally back together and the car is dyno tuned we will see how much power she makes, and you can then tell me you told me so
i'm also gonna try my hand at putting the "power lynz" into the ports to create a boundary layer for the air, increasing velocity and improving fuel atomization.
what were the rest of your mods, gears, transmission etc.
big cam (dont remember specs off the top of my head), 10.75:1 compression, headers, p&p heads, custom intake plenum and throttle body, 1.6 rockets, built 700r4, 3in exhaust
Thanks. I still get on here pretty often, just read most of the time now, don't post too often. Still have plans to build a turbo hybrid motor, just don't seem to have the time or money anymore
Honestly I'm curious to see the outcome and you are right. Not much you can do to make them much worse then they started out as.
fasteddi, what did you do about the intake manifold heat riser ports in the middle exhaust ports on each head? Seems like this would be bad for turbo exhaust flow if half of 2 of the cylinders are losing exhaust flow to the intake???
this is what i'm talking about for those who do not know. they were used to heat up the intake manifold and thus the carb back in the carb days but I don't see why our engines need them. Looks like GM designed these heads for a carb'd engine and left em in the casting for 9 years after switching to port fuel injection
If it was me I would melt down some cast aluminum, fill the holes and then blend the bowls...well that's what we do with the OEM Oldsmobile heads when porting them.
Unless there is another way to block the crossover you will probably be fine just leaving them open.
this is what i'm talking about for those who do not know. they were used to heat up the intake manifold and thus the carb back in the carb days but I don't see why our engines need them. Looks like GM designed these heads for a carb'd engine and left em in the casting for 9 years after switching to port fuel injection
I didnt have those on my heads. 1991 3.1l heads. Quite honestly ive never seen that before. And trust me I knew every mm of my iron and alum heads
you are right that would be a big pain if you have that there.
If it was me I would melt down some cast aluminum, fill the holes and then blend the bowls...well that's what we do with the OEM Oldsmobile heads when porting them.
Unless there is another way to block the crossover you will probably be fine just leaving them open.
I already have the new valves in and everything. i'd hate to have to do that. maybe this won't kill performance too bad. I might try to block it off on the intake side by welding something in there to block it.
that port to the right of the left intake port is where the exhaust flows to the lower intake. I can see them in your heads, fasteddi. But I guess they might have been blocked off inside the exhaust port so you never noticed and like me thought it was a coolant port.
I know my '85 heads had these, but I never looked at the new heads I had ported close enough to see if these were in there on them . (The new heads are from a 1989 2.8L) In all the pics I was sent, this was never shown. Fingers crossed that they don't have it either. I don't have the heads at my house right now to confirm.
I found a pic of some falconer heads on here and if you look real hard you can see that his heads have the heat riser port in the middle exhaust port too.
