Hybrid View
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12-10-2006 12:02 AM #1
454 Compression ratio -- small cc head or domed piston
I want to switch to aluminum heads and raise my CR to 9.2 - 9.5. I am running road race tracks and am using an oval port Air Gap with a Comp cam 280 and a 750 Holley. RPM range is 3000 - 5500.
My main goal is to get rid of the weight of the CI heads. While I am at it I thought going up in CR would be worthwhile.
Edelbrock says that I can use a 60459 (110cc) head and get 9.5 with domed top pistons or 60499 (100cc) with flat top pistons and get 9.2. Obviously a lower cost route.
Any thoughts?
Jim
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12-10-2006 07:31 AM #2
You will also notice a significant gain in your low and midrange power curve too.Compression is relative to making HP. Your cam and cylinder heads need to be matched, I have learned that with a better flowing set of heads, you don't require as big of cam anymore.The heads move air more efficiently without having the valve held open as long by a bigger lift cam.9.65 @ 137 MPH 1.39 60' More left in the car.
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12-10-2006 08:03 AM #3
Well my thoughts are the more fuel/air you can get in you cyclinders
the more H.P. your make. I would go with 110 cc head with the dome pistion if I could afford it.
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12-11-2006 06:04 AM #4
Oh sorry. yes i agree the open chamber head will flow way better than a closed chamber head.9.65 @ 137 MPH 1.39 60' More left in the car.
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12-12-2006 05:20 PM #5
Edelbrock claims the flow on these two heads is exactly the same. They call the chamber a semi-open design.
Thoughts?
Jim
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12-12-2006 10:24 PM #6
use a small chamber and a dome piston for ultimate compression and power
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12-14-2006 09:26 PM #7
I had the edelbrock rpm performer marine heads with 11.25-1 compression. it ran on pump gas and made 550Hp and 513 TQ this was a 427 BBc with a hydraulic roller cam9.65 @ 137 MPH 1.39 60' More left in the car.
The engine looks awesome, I like the low intake. That'll be some eye candy when the hood is popped.
1968 Plymouth Valiant 1st Gen HEMI