[PAUL K]

Originally Posted by tekuhn

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.

Ports size is part of it. They seem to work well on aftermarket blocks.

[PAUL K]

Originally Posted by ChiefCrazyCanuck

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.

Your car runs well. I don't think your car is the example Slowbird was talking about.

[Bill Eveland]

How much compression and shift points? And rest of combo?

Originally Posted by ChiefCrazyCanuck

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.

[ChiefCrazyCanuck]

Ports have had the pushrods moved, so ports are naturally larger still. Over 14:1 CR

[Bill Eveland]

380 cfm? Cam?

[ChiefCrazyCanuck]

Whole point of post being to say that the KRE HP heads are a good alternative to the Edelbrocks. Even in smaller displacement engine combinations that have a higher level of development. These heads easily outpaced a very nice set of equivalent E-wide heads on a similar engine package

IMO, and as it should come as no surprise the short turn radius height improvement is an advantage.

The motor is nowhere near matched to the car. Too many projects. Darby knows the story.

[ChiefCrazyCanuck]

And to be clear, I know this post started as a conversation about standard PR location KRE HP heads. In that context the KRE HP heads as cast IMO could offer an advantage over the E heads with the same combustion chamber size on an engine combination that required "more".

As Slowbird alluded to the increase in runner volume is largely as a result of the raised port. Which increases the intake runner volume. This does not equate to a larger CSA everything else being equal, only that the longer tract adds to volume. Other variables depend on valve diameter, bowl, etc.

[Steve C.]

As cast the HP head already has a 0.200 Offset pushrod location on the intake.

[tekuhn]

Originally Posted by PAUL K

Ports size is part of it. They seem to work well on aftermarket blocks.

If the only difference is actually the block itself, there must be a reason. Difference in the valve valve relief cuts? Maybe it's more due to anyone who spends the $$ to go aftermarket block is also not going to skimp on machine work and quality components. Don't know, but it would be hard to explain the block itself making more power with a certain head. Not saying it's not true - I have no experience either way - just hard to explain.

[PAUL K]

Edelbrock heads with an off-set pushrod have been 8.0 at approximately 3300 lbs. with nitrous on a factory block short block.

Edelbrock heads with standard pushrod location have been 8.90 naturally aspirated at a similar weight on a factory block.

Please list some times and weights of Hi-port heads on stock block combinations as asked in post 44.

I am curious to see the all the extra power the hi-port will make on a factory block.

[BLANK1]

I have a stock block 461 with High Ports in my 68 GTO. Bottom end has 4.155 ROSS pistons, RPM rods, Ohio forged crank and studded 2 bolt caps. Northwind and a 1050 Dominator. Used to have 78cc E-heads just cleaned up with 2.11/1.66 valves and a 2.3X1.2 intake opening. Had a Lunati solid roller 255/263 @ .050 .4176 lobes 109 LSA 1.6 rockers and about .650 lift. CR was about 10.8 used 93 pump gas. Best time was a 10.97 @ 122 mph at 3850 lb race weight. TH400 with 4000 stall FTI converter. 3.73 gears. Changed only the heads to 80cc High Ports with 2.4X1.2 intake opening otherwise as cast heads with 2.2 and 1.7 valves. Compression now 10.63. Couldn't match time with E-heads. Came close but couldn't run tens. Mostly 11 teens to 11.20's. Ran that mostly with the E-heads also. Changed cam to a Jones custom solid roller everything else the same. 316/320, 263/269 @ .050, .421/.412 lobe lift and 110 LSA. Lift is .658 and .640. Best time with this cam is 10.97 @ 123 mph with a 1.61 60 ft. Mostly runs 11 teens and 11.20's. Next thing to try is maybe a higher stall converter or more cubes? Was hoping for consistent 10's. I do have a Lunati 271/278 @ 050 solid roller I was thinking of trying.

[PAUL K]

Originally Posted by tekuhn

If the only difference is actually the block itself, there must be a reason. Difference in the valve valve relief cuts? Maybe it's more due to anyone who spends the $$ to go aftermarket block is also not going to skimp on machine work and quality components. Don't know, but it would be hard to explain the block itself making more power with a certain head. Not saying it's not true - I have no experience either way - just hard to explain.

Im trying to be PC and respectful to the folks that put the effort into producing the Hi-port heads.... We have found very little gain if any using them on a factory block compared to a well prepped Edelbrock head. There maybe a few reasons for this but I feel it's irrelevant. It's a good head and shines bright on the right application, but I doubt it's going to be on a factory block.

[pastry_chef]

Originally Posted by BLANK1

Next thing to try is maybe a higher stall converter

I like the more stall idea.
Maybe some intake work if it is stock.

3850 lbs is heavy.

[ChiefCrazyCanuck]

My HP head combo vs. the E head combo was .31 in ET quicker and almost 4 MPH faster in worse air. Similar combos and some variances, but then consider neither of these cylinder heads I have run have a "part number" that anyone can order. Hard to be objective accordingly.

No way to make the comparison you are suggesting in a fair manner. Gotta be at least 50:1 ratio of Edelbrock Pontiac non d-port headed combo sales to KRE HP heads to date.

Just saying that the comparison is not as straightforward as it may appear on the surface.

[ChiefCrazyCanuck]

Originally Posted by PAUL K

Im trying to be PC and respectful to the folks that put the effort into producing the Hi-port heads.... We have found very little gain if any using them on a factory block compared to a well prepped Edelbrock head. There maybe a few reasons for this but I feel it's irrelevant. It's a good head and shines bright on the right application, but I doubt it's going to be on a factory block.

I agree, for most the E-Head is the way to go and offers a lot of performance value. The casting quality is superb, and modification for modification from one to another it is likely not worth the hassle if you own the E-heads already. Chasing big numbers on a stock block engine is probably not wise long term, I guess I will be one to find out

[ChiefCrazyCanuck]

Originally Posted by BLANK1

I have a stock block 461 with High Ports in my 68 GTO. Bottom end has 4.155 ROSS pistons, RPM rods, Ohio forged crank and studded 2 bolt caps. Northwind and a 1050 Dominator. Used to have 78cc E-heads just cleaned up with 2.11/1.66 valves and a 2.3X1.2 intake opening. Had a Lunati solid roller 255/263 @ .050 .4176 lobes 109 LSA 1.6 rockers and about .650 lift. CR was about 10.8 used 93 pump gas. Best time was a 10.97 @ 122 mph at 3850 lb race weight. TH400 with 4000 stall FTI converter. 3.73 gears. Changed only the heads to 80cc High Ports with 2.4X1.2 intake opening otherwise as cast heads with 2.2 and 1.7 valves. Compression now 10.63. Couldn't match time with E-heads. Came close but couldn't run tens. Mostly 11 teens to 11.20's. Ran that mostly with the E-heads also. Changed cam to a Jones custom solid roller everything else the same. 316/320, 263/269 @ .050, .421/.412 lobe lift and 110 LSA. Lift is .658 and .640. Best time with this cam is 10.97 @ 123 mph with a 1.61 60 ft. Mostly runs 11 teens and 11.20's. Next thing to try is maybe a higher stall converter or more cubes? Was hoping for consistent 10's. I do have a Lunati 271/278 @ 050 solid roller I was thinking of trying.

Were the actual CCs on the chambers physically measured and confirmed with both the E-heads and the HP heads? Or were the measurements nominal?

[BLANK1]

ChiefCrazyCanuck, yes they were both measured.

[slowbird]

Originally Posted by BLANK1

I have a stock block 461 with High Ports in my 68 GTO. Bottom end has 4.155 ROSS pistons, RPM rods, Ohio forged crank and studded 2 bolt caps. Northwind and a 1050 Dominator. Used to have 78cc E-heads just cleaned up with 2.11/1.66 valves and a 2.3X1.2 intake opening. Had a Lunati solid roller 255/263 @ .050 .4176 lobes 109 LSA 1.6 rockers and about .650 lift. CR was about 10.8 used 93 pump gas. Best time was a 10.97 @ 122 mph at 3850 lb race weight. TH400 with 4000 stall FTI converter. 3.73 gears. Changed only the heads to 80cc High Ports with 2.4X1.2 intake opening otherwise as cast heads with 2.2 and 1.7 valves. Compression now 10.63. Couldn't match time with E-heads. Came close but couldn't run tens. Mostly 11 teens to 11.20's. Ran that mostly with the E-heads also. Changed cam to a Jones custom solid roller everything else the same. 316/320, 263/269 @ .050, .421/.412 lobe lift and 110 LSA. Lift is .658 and .640. Best time with this cam is 10.97 @ 123 mph with a 1.61 60 ft. Mostly runs 11 teens and 11.20's. Next thing to try is maybe a higher stall converter or more cubes? Was hoping for consistent 10's. I do have a Lunati 271/278 @ 050 solid roller I was thinking of trying.

You started out with a 255 cam them a 263 cam (didn't seem much improvement from the sounds of it) and now you're looking at trying a 271 cam?

[ChiefCrazyCanuck]

The almost 2 tenths CR reduction from the HP heads would have some kind of effect. And you mention that the results were very similar from the Edelbrocks to the KRE HP heads generally speaking.

[ChiefCrazyCanuck]

Originally Posted by slowbird

You started out with a 255 cam them a 263 cam (didn't seem much improvement from the sounds of it) and now you're looking at trying a 271 cam?

I agree with Slowbird. Might want to look closer at camshaft duration, especially with the relatively low CR you are running. Consider advancing the cam you have provided that you have sufficient P/V clearance.

Too many times people change cams without advance/retard changes to the existing profile. These changes can help you make an informed decision as to what changes if any are required to the existing cam.