Port comparisons

Brian H. (BigDrag) has an interesting post in his files comparing CNC oval port to CNC round port heads which shows an obvious torque curve advantage for the round port heads but a little less maximum BHP. I would assume this was a "side-by-side" dyno comparison, e.g., only the heads were changed on the same engine for the comparison and the compression ratio with both builds was the same.

The round port torque curve is great for street cars with no extreme performance aspirations, but note that it's really unfair to compare two heads with one cam unless that is the cam you wish to use in your engine. A different cam with the oval ports might give significantly different and superior torque numbers.

Just a caveat - pick your heads to match your camshaft, overall build, and driving intentions...

Hi George:

I see nothing "unfair" about making the comparison. The numbers are real and reflect the difference in performance between the two engines. There may have been some minor additional tweaking of which I am unaware, but it makes no difference... the before and after results speak for themselves. This came about after a test drive by Henry when he recognized that the oval ports did not have any low end punch. No theory here, actual testing.

Certainly your comment "..pick your head designs to match your camshaft..." was not directed at me. Getting me involved in this level of detail would be a real joke. I am not an engine designer and feel it is wise to defer to people who do this for a living. After all, who knows better than the person that lives and breathes this work every day? Most of the rest of us are "experienced amateurs", at best. It seemed to me that the proper course of action was to communicate my performance desires in non-technical language to the experts and then get out of the way and let them do their thing. Perhaps I am not the typical enthusiast? But I have made these sorts of comments before on other threads.

The bottom line is that I am delighted with the performance, so the process worked for me. Different strokes for different folks!

I hope you are as happy with your new car as I am with mine.

At first blush, all that top end power looks great, but then you think, "hey, I'm probably not going to use that top end power more than 5% of the time. The other 95% I'll be tooling around in the lower rpm range, where torque is king". I don't know how the rest of you drive, but I like to cruise around town in 4th gear, at 2200 rpm, rather than 3rd gear, at 3300 rpm. Brian's motor sounds like the perfect choice...lots of go and lots (and lots) of torque. I'm sorry I wasn't able to come in and try out his car.
Ron

Brian, your engine nakes great torque for a street engine, I was just pointing out that in a way, its an apples to oranges comparison.

Ron, I hope you really don't drive your car around in a higher gear at 2,200 RPM - IMO heavier engine loads with lower oil pressure and less cooling air from the fan is not a good idea.