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Ok so here -- once and for all -- im going to explain why aluminum heads are better than the iron ones. Its really really simple.
They flow better.
How much better you ask? Well let me put it this way. I found a flowbench sheet for a set of 3100 (3.1 Gen II Aluminum) heads from a friend of mine that knows the 3x00 engine backwards and forwards. The 3100 heads (Gen II) come with the same valves as our stock iron heads, 1.72/1.43 (intake/exhaust). However the valves are canted, which helps airflow at higher rpms because the valves dont get in the way of each other, and keeps the air flowing well.
The exhaust ports have been D shaped instead of O shaped. The difference also allows for better airflow at higher RPMs, while maintaining good flow at lower RPMs as well.
Now all said and done -- these heads, the Gen II aluminum heads found on any 1996 Grand Am GT -- flow as much as a set of 900.00 ported iron heads.
I took the flowcharts my one friend gave me, and then talked to Tiago of Force Fed Fabrications. He gave me flow charts for his fully ported iron heads. Worked on by Norris Racing Tech (and I personally know this for a fact), a LOT of research went into these heads to make them flow optimally - including researching larger valve sizes and port shapings and everything.
In the end they were made to flow 158cfm on the intake side @ .500 lift and 142cfm on the exhaust side @ .500 lift. (the flow on the aluminum is better all around, but ill just show this cause its what i remember...off the top of my head).
I took the stock flowbench from the Gen II heads, and found them to flow 162cfm @ .500 intake and 139cfm @ .500 exhaust.
Wow is what I said. We are talking about a stock aluminum head, one that hasnt been ported or polished or gasketmatched. One that has all the stock casting flaws and everything -- flowing as much as a completely ported Iron head. Again:
Fully Ported Iron Heads (@.500" lift):
158cfm Intake / 142cfm Exhaust
Stock Aluminum Heads (@.500" lift):
162cfm Intake / 139cfm Exhaust
Thats insane. I can only imagine what a set of ported aluminum heads would flow -- and I plan to have it checked when I get mine ported.
What that means, is that if I took one of Tiagos turbo kits and threw it on my car, I would get the same results he has. Without any of the work. And it can only go up from there. Get It?
There is no strength problems, my car never overheats, and the aluminum topend actually shaves off a LOT of weight. One of the aluminum heads weighs maybe 20-25 lbs. ONE of the iron heads feels like it weighs around 40-50 lbs. means you are losing 50lbs right there just by switching. After using these heads on my car, I will never put the iron paperweights back on.
That is my opinion and I'm sticking to it. Aluminum heads on your 3.4L RWD engine is the BEST "bolt-on" (yes its a bolt on cause they bolt right up with very little modification) you can do. Hands down. Update to the newer technology and toss the 10-year old crap that GM decided to stick with when they put the engine together.
Just my .02.
-R
p.s. i also found out just recently that a set of 3400 heads (2000+ model year 3400) flow 200 cfm on the intake and 180cfm on the exhaust. thats just insane! May 20th, 2006 I am going to dyno the 3.4 with its new clutch I just put in and ill correct my sig and put new numbers up. then its off to the track! we'll see what this setup is capable of. :)
They flow better.
How much better you ask? Well let me put it this way. I found a flowbench sheet for a set of 3100 (3.1 Gen II Aluminum) heads from a friend of mine that knows the 3x00 engine backwards and forwards. The 3100 heads (Gen II) come with the same valves as our stock iron heads, 1.72/1.43 (intake/exhaust). However the valves are canted, which helps airflow at higher rpms because the valves dont get in the way of each other, and keeps the air flowing well.
The exhaust ports have been D shaped instead of O shaped. The difference also allows for better airflow at higher RPMs, while maintaining good flow at lower RPMs as well.
Now all said and done -- these heads, the Gen II aluminum heads found on any 1996 Grand Am GT -- flow as much as a set of 900.00 ported iron heads.
I took the flowcharts my one friend gave me, and then talked to Tiago of Force Fed Fabrications. He gave me flow charts for his fully ported iron heads. Worked on by Norris Racing Tech (and I personally know this for a fact), a LOT of research went into these heads to make them flow optimally - including researching larger valve sizes and port shapings and everything.
In the end they were made to flow 158cfm on the intake side @ .500 lift and 142cfm on the exhaust side @ .500 lift. (the flow on the aluminum is better all around, but ill just show this cause its what i remember...off the top of my head).
I took the stock flowbench from the Gen II heads, and found them to flow 162cfm @ .500 intake and 139cfm @ .500 exhaust.
Wow is what I said. We are talking about a stock aluminum head, one that hasnt been ported or polished or gasketmatched. One that has all the stock casting flaws and everything -- flowing as much as a completely ported Iron head. Again:
Fully Ported Iron Heads (@.500" lift):
158cfm Intake / 142cfm Exhaust
Stock Aluminum Heads (@.500" lift):
162cfm Intake / 139cfm Exhaust
Thats insane. I can only imagine what a set of ported aluminum heads would flow -- and I plan to have it checked when I get mine ported.
What that means, is that if I took one of Tiagos turbo kits and threw it on my car, I would get the same results he has. Without any of the work. And it can only go up from there. Get It?
There is no strength problems, my car never overheats, and the aluminum topend actually shaves off a LOT of weight. One of the aluminum heads weighs maybe 20-25 lbs. ONE of the iron heads feels like it weighs around 40-50 lbs. means you are losing 50lbs right there just by switching. After using these heads on my car, I will never put the iron paperweights back on.
That is my opinion and I'm sticking to it. Aluminum heads on your 3.4L RWD engine is the BEST "bolt-on" (yes its a bolt on cause they bolt right up with very little modification) you can do. Hands down. Update to the newer technology and toss the 10-year old crap that GM decided to stick with when they put the engine together.
Just my .02.
-R
p.s. i also found out just recently that a set of 3400 heads (2000+ model year 3400) flow 200 cfm on the intake and 180cfm on the exhaust. thats just insane! May 20th, 2006 I am going to dyno the 3.4 with its new clutch I just put in and ill correct my sig and put new numbers up. then its off to the track! we'll see what this setup is capable of. :)
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