Stock heads have 163 cc intake and edelbrock performers for centerbolt have 165 cc intake. How much better are they. trav

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1987 Camaro Iroc-Z Z-28 with a TPI 5.7
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set at 50 psi, MSD Cap, MSD 8.5mm wires,
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no one can take away.

 

They are much better than the stock heads. The intake ports are only one of many things that are different. The Edelbrock's have bigger valves (2.02"/1.60" to stock 1.94"/1.5") which allow are higher maximum amount of air to enter the combustion chamber, which is smaller (60cc to 64cc) which increases compression ratio slightly. The actual shape of the combustion chamber is also a better design than stock heads, and permits a more complete burn, and therefore more power.

Also, on a side note, the fact that the Edelbrock's intake port is almost the same as the stock heads is the main reason that I chose these heads over others like AFR and Trick Flow. The TPI intake is designed on velocity, it gives air in a small diameter tube a high velocity to get the maximum amount of air into the combustion chamber. When you put on a head with a larger intake port the velocity of the air slows when it enters it because it has to fill out into the chamber, this seems to be counter-productive to me. While a larger intake port will allow a larger maximum amount of air to pass through it, both heads still meet the same restriction when the air reaches the valves, so why not keep the intake port small and retain the velocity?

This is the thought process that I went through, and it seems logical to me.

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Black 88 GTA L98
New engine is in!
ZZ4 bottom end, Edelbrock 6085 heads, LT4 HOT cam, GMPP 1.6 RR's, ported stock TPI, SLP 1 3/4" headers, no cat, Dynomax cat-back
E.T.F.A Member #11

 

thanks

 

The Edelbrock's jave two major improvements over the stock heads, flow and velocity.

They flow much more air right out of the box and the velocity of the air is higher. Both of these translate into more power.

I've got a lot of head flow numbers saved as txt files. If you, or anyone else, are interested, email me and I'll send them

Hope this helps.

Jake

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1986 Corvette Coupe, 415 CID, Edelbrock 6073s, ZZ9