[PAUL K]

The lobe design has a big effect on the required spring pressures but so does the weight of the valve train. I believe some of the old Comp stuff calls for 160 seat and 450 open.... That's what some of the current hydraulic rollers are set up with.

[Steve C.]

"...so does the weight of the valve train"

Paul brings up a very good and obvious point. Example, some of the higher flowing aftermarket alum heads using something like a 2.190" dia valve with a longer stem length for a 1.900" installed height. Or the high-port head packages that include 2.20-inch intake valves. These lead to a heavier valvetrain mass.

In my case I have a longer stem 2.150" dia but they are custom Ferrea Hollow Stem Valves to help reduce weight.


.

[Steve C.]

Our secret squirrel with the high-port heads 2.20-inch intake valve at 2.000" installed height with 3/8" pushrods might be using the Comp 959 spring rated at 236 lbs seat pressure with his solid roller cam.


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[slowbird]

Some what back to the topic. Any other pg 480ci or less hp headed combos out there? Power and et/mph results?
A few years ago there was a high powered stock block build that was documented here, made 800+ (i think it was race gas though, and it's struggling to show the hp on the track), any other builds??

[PAUL K]

Originally Posted by slowbird

Some what back to the topic. Any other pg 480ci or less hp headed combos out there? Power and et/mph results?
A few years ago there was a high powered stock block build that was documented here, made 800+ (i think it was race gas though, and it's struggling to show the hp on the track), any other builds??

I doubt you'll find many examples of 480 cid or less pump gas builds making good power using hi-port heads... There is a "reason" why the E-heads are TTF!

[grandville455]

My Stock Block Drag week 468 motor made 650 hp on 91 pump gas, drove it all over and had a 265/270 solid roller with my KRE D Port HEADS with 700 lift. FWIW

[tekuhn]

Originally Posted by PAUL K

I doubt you'll find many examples of 480 cid or less pump gas builds making good power using hi-port heads... There is a "reason" why the E-heads are TTF!

Why? Are you saying that High Ports require more displacement (port velocity) to make good power? Not trying to argue, just curious what's the technical basis of your statement.

[slowbird]

Originally Posted by grandville455

My Stock Block Drag week 468 motor made 650 hp on 91 pump gas, drove it all over and had a 265/270 solid roller with my KRE D Port HEADS with 700 lift. FWIW

But kre d-ports are better tha hp heads on stock blocks

[i82much]

Originally Posted by grandville455

My Stock Block Drag week 468 motor made 650 hp on 91 pump gas, drove it all over and had a 265/270 solid roller with my KRE D Port HEADS with 700 lift. FWIW

did you put many street miles on that engine?

[mysticmissle]

drag week and he practically uses it as his daily driver lol

[Steve C.]

Ask secret squirrel what the intake runner volume is for the as cast HP heads.... about 277 cc's I believe. That would be for the claimed 330 cfm. Now how many cc's would a typical 72cc Edelbrock head be ported to a similar 330 cfm... about 235 cc's ?


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[slowbird]

Originally Posted by Steve C.

Ask secret squirrel what the intake runner volume is for the as cast HP heads.... about 277 cc's I believe. That would be for the claimed 330 cfm. Now how many cc's would a typical 72cc Edelbrock head be ported to a similar 330 cfm... about 235 cc's ?


.

But the HP head has roughly 1/2 longer ports

[Steve C.]

OK then how does that relate to tekuhn inquiry as to the port velocity ?


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[tekuhn]

Originally Posted by Steve C.

OK then how does that relate to tekuhn inquiry as to the port velocity ?.

He's pointing out that if the HP has a longer runner, that could explain the higher port volume and cross-section and velocity might not be as different as implied.

[slowbird]

Originally Posted by tekuhn

He's pointing out that if the HP has a longer runner, that could explain the higher port volume and cross-section and velocity might not be as different as implied.

Correct sorry for the confusion.
The hp head most likely does have slower velocity to some extent in the bowl area due to it having bigger valves.
Some quick math shows an average csa on the hp head roughly 3sqin (using 277cc and 5.7in port) and the e-head is roughly 2.8sqin (using 235cc and 5.1in port)

[Steve C.]

Larger-area runners will improve the flow at higher engine speeds, but may also slow the filling of the cylinders at lower engine speeds. Longer runners will sometimes impact the power and torque production at lower engine speeds while shorter runners may move the peak torque rpm higher up.


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[Bill Eveland]

Mine use a 2.25 valve i believe about 6.2" long. I dont have the raised lifters so using a 10.4" pushrod also.

[Steve C.]

Intake: Ferrea 2.230" dia titanium x 6.250" stem
0.5000" lobe lift w/1.7 ratio
Manley 221448 springs installed at 2.100"

HP heads / Victor intake
4.5 stroke / 526 CID
13.2:1
920.4 hp at 7000 rpm

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[ChiefCrazyCanuck]

Originally Posted by PAUL K

I doubt you'll find many examples of 480 cid or less pump gas builds making good power using hi-port heads... There is a "reason" why the E-heads are TTF!

Might be my stock block high port engine that Slowbird is referring to. .065" over 455 (470). Made 830 on the dyno, made some minor changes but did not re-dyno. Ran 9.6 at almost 139 MPH at 3600 lbs in a car that hasn't really been optimized. Runs OK on nitrous (8.90s), just really haven't chased it to get it perfect. E85 BTW.

[PAUL K]

Originally Posted by grandville455

My Stock Block Drag week 468 motor made 650 hp on 91 pump gas, drove it all over and had a 265/270 solid roller with my KRE D Port HEADS with 700 lift. FWIW

Excellent! You should try some Hi-ports and get back to us