Turbo heads
Originally Posted by Pro Stock John
Is there any difference between OEM and aftermarket LT1 castings, in terms of deck thickness? If so, and if it's significant, I would go aftermarket. I don't anything about valve sizing, but I'd at least go 2.02/1.57.
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From: Arlington TX
As far as I know all AFR LT1 heads use the LT4 intake. So the essentials are deck thinkness, large combustion chamber and... What about valve sizes? Should the exahust valve size be closer to the size of the intake valve?
Originally Posted by Pro Stock John
Are all the AFR's LT4 style? There are 2 or 3 LT1 castings for LT1's?
Originally Posted by TurboZ28
As far as I know all AFR LT1 heads use the LT4 intake. So the essentials are deck thinkness, large combustion chamber and... What about valve sizes? Should the exahust valve size be closer to the size of the intake valve?
Larger combustion chamber = Trickflows or AFR since LT1 castings can only be opened to around 58cc.
Valve size = biggest valves are in the trickflows or AFR's (I believe mine are 2.08/1.60)
Readily available intake manifolds = LT1 intake available...... = Trickflow heads
To me the decision is easy...Trickflows or AFR's depending on if you can get an LT4 intake...
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on the trick flow, I recived a paper with mine saying that they are available in 64cc and 72 cc's, the ones I got are 62 cc's. valve size on mine are 2.02 and 1.60 stock, but you can drop a 2.05 right in they say. but comparing stock to stock trick flows, wow, what a differance a lot better head.
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From: Boise Idaho
Originally Posted by Silver02
Does having heads that flow substantially more help with a turbo?
I have heard the general rule is that on 17 psi (some say 14.7, but that takes in no loss from blower or turbo set up) your car will double its na numbers, so what ever helps a na engine will help the fi engine as well.
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From: Just outside of Palm Springs Ca.
Here is my experience with this type of powerplant.
-Heads can't flow too much and any increase will net power gains.
-Deck thickness becomes a problem with the LT* engines when using stock heads and they start to have gasket problems beyond about 500+ RWHP with an auto maybe a little more with a manual I have seen them literally "PUSH" the gasket out with no signs of detonation or knock at all.
-Exhaust to Intake ratio is VERY Important when it comes to spooling the turbo well, if you are interested, we offer Trick Flow or AFR castings built for turbo applications for LT1/4's and LSX's on a custom order basis.
The bottom line is....the turbo will make great power without addressing the I/E ratio and flow numbers...but it will make more EVERY TIME with the proper port work done to the heads.
-Heads can't flow too much and any increase will net power gains.
-Deck thickness becomes a problem with the LT* engines when using stock heads and they start to have gasket problems beyond about 500+ RWHP with an auto maybe a little more with a manual I have seen them literally "PUSH" the gasket out with no signs of detonation or knock at all.
-Exhaust to Intake ratio is VERY Important when it comes to spooling the turbo well, if you are interested, we offer Trick Flow or AFR castings built for turbo applications for LT1/4's and LSX's on a custom order basis.
The bottom line is....the turbo will make great power without addressing the I/E ratio and flow numbers...but it will make more EVERY TIME with the proper port work done to the heads.
Running a larger cc head will have less material around the valves and flow more in the lower lift. Sometimes smaller valves will actually flow more overall, depends on the head. Most people look only at the highest number in a flow chart, but in reality the flow numbers in the lower lift is just important if not more.
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Originally Posted by pwrtrip75
Running a larger cc head will have less material around the valves and flow more in the lower lift. Sometimes smaller valves will actually flow more overall, depends on the head. Most people look only at the highest number in a flow chart, but in reality the flow numbers in the lower lift is just important if not more.