quote:Originally posted by Daniel_Jones:
...A bit of a nit but the 3V port is larger than a 2V...
Ha, ha, ha...Dan my friend, yes, it is a bit of a nit. Rather than seeking technical accuracy, I was attempting to paint a picture in my reader's minds. But you go on picking nits! I wouldn't have you change a bit, I love your engineer's eye for detail.
quote:Originally posted by Daniel_Jones:
...Saying that an AFD 2V head can support over 600 HP out-of-the-box is somewhat misleading....I know of a dyno verified stock displacement 351C with unported (NHRA legal valve job only) open chamber 4V heads that made 630+ HP...
Yes, I am quoting AFD/CHI sales BS. But, again, rather than seeking technical accuracy, I'm attempting to make a point, that these new 2V heads are very very good, and all the head the majority of enthusiasts will ever need. The statement is no less accurate than your statement about 630 bhp with unported 4V heads. In either case, its not something that just anybody can go out and do, any day of the week. You were making a point by citing the 4V motor's bhp, the same way I'm making a point by saying the 2Vs will support 600 bhp.
quote:Originally posted by Daniel_Jones:
...Increasing RPM and cam timing come at a durability cost but better airflow does not....
To make a certain bhp, with a certain displacement motor, at a certain rpm, requires a certain amount of airflow. Heads capable of flowing more than that, are overkill. Having written that, I will agree that I would rather have a head that achieves my target flow with 0.500" lift, rather than 0.600" or 0.700" lift. This would allow me to use a milder cam, and a more reliable valve train. Other head characteristics are equally important to power production however, such as port velocity, port contour and combustion chamber design. The new heads have advantages over the Motorsport heads in that respect, and computerized dyno software does not do well in factoring those things into the equation.
quote:Originally posted by Daniel_Jones:
...On a milder engine the gap between the heads will close and may well be influenced by what headers and intake are available....
The gap between heads closes because on a milder motor, the race heads are overkill, at lower lifts they don't flow any better than the non-race heads. Or to put it differently, the mild motor can't use the race heads to their potential.
Your comment about headers & intake brings to my mind a good point. The combination of parts is what needs to be considered, not just the heads alone. And to have a feel for the combination, you need a good idea for what the owner wants to accomplish. Most of the time, for the majority of readers here, I'm not writing to somebody who wants cutting edge performance, their combinations are going to be milder. The DTBB needs the cutting edge info too. Who else is going to teach us about beehive springs if not you?!
Usually, before I make specific recommendations, I ask a bunch of questions, and get a feel for what an owner expects, and what aspects are most important to them, and most importantly, what the budget is. Nobody can write generalizations here and be accurate for everybody. When I write in general, I have in mind what I consider to be the average owner, somebody who wants a reasonably mild combination, good driveability, even a bit of fuel economy. Performance above 6000 rpm is not important to them. Reliability, a wide powerband and sharp throttle response being more important than a peak dyno number. When I'm asked about cutting edge performance issues by an owner, somebody who has to have 600 bhp, that sort of thing, I often refer them to you! lol...
My bottom line is that the folks here get their questions answered, the help they are seeking.
quote:Originally posted by Daniel_Jones:
...The CHI 3V's are excellent heads but in terms of all out power production the raised exhaust port heads have an advantage....
I know how much you like the Motorsport heads. And truth be known, never forget, I do too. But the reality is, again, most readers here will never need the high port heads to achieve their goals. A second and equally important consideration is the ease of obtaining the parts. The Motorsport stuff is more difficult to locate than the parts available brand new.
quote:Originally posted by Daniel_Jones:
...Have you verified this is true, Goerge? I tried following up on the rumor that CHI was going to price match the Edelbrock 2V head price but found it wasn't true...
One of the 2 companies had a sale recently, I forget which one. Perhaps that was the pricing you heard about. ..I logged onto CHIs site yesterday to grab a link to a video of a Jon Kaase testimonial. While I was there I noticed the CHI had made many improvements to their web site, so I gave it a quick "tour". One price I remember is that of the 4V head; it was priced at $2050 in street performance set-up. I don't remember the other prices. I remember the 4V price because the CHI 4V head is the one I'm considering, instead of using cast iron 4V heads. However, I'm still on the hunt for the A331 intake, if I find one, I may spring for the A3 heads. In fact, if you hear of an A331 for sale, I would appreciate you keeping me in mind.
your friend on the DTBB