pcmhacking.net

This one? best images I could get but I guess someone who knows how to clean them up to be at least easily readable can run their magic?

Yeah, that looks like it

13.7mm valve lift......

immortality wrote:Yeah, that looks like it

13.7mm valve lift......

yeah pretty standard. My mild cam has 11.94mm.

V6 heads just don't benefit from large lift, anything over 0.525" on the best of heads for both buick and ecotec becomes rather minuscule in gains for loss of reliability.

Nahh. I've seen flow figures for ecotec heads that continue to increase flow to almost .600" for basically stock heads. Not only that but if you can lift the valve faster you have much more area under the curve. Clearly the ecotec heads like this as shown by the high ratio rockers giving a good increase.

Buick heads are a bit different but at the end of the day if the heads are set up right reliability shouldn't be an issue. At higher lifts roller tipped rockers are a must really to reduce the side loading on the valve stem and wear in the valve guide.

not with ZZP heads I haven't they peak around 540 ish thou and plateau, the increase from low 500s to 600 is minimal.

It might be a bit less with buick heads as they flow better than ecotec once worked, even outperforming ZZP out of the box as we are finding with the current engine project and HSD's work on the ZZPs which are who originally further developed the formula heads to push them to 340hp mark.

It all comes down to the dynamics of the engine as a whole, big lift doesn't always result in best power, goes backwards in most cases. Its a balance between max flow and quality of flow, complex fluid dynamics at play.

Yes, max lift with stable flow. Once the flow becomes turbulent the port will back up

The Holden V8 head in the early days never went much over .500" lift, now good porters can take those same cast iron heads and have them flowing stable to .900" lift and run them with solid rollers close to .700" lift making power similar to LS engines. Holden 355 with cast iron heads making over 500hp no problems these days. 10 years ago that was the territory of exotic engine builds only and supposedly only with alloy heads....

Horses for course.....

here's what i have, couple of those same pages in higher res

2 separate exhausts not sounding right? and trialing 6:1 design for "better sound" they got to be kidding right?

Yeh bit odd

I reckon. 6:1 sounds like poo. even 3:2:1 like in most cars with v6 isn't right and responsible for the average sound and lower performance. 2x 3:1 is ideal for a v6 due to its peak resonance tuning being best from engine ranging in cylinders from 3-4 on even firing. 2 split systems on a v6 gives you 2 ideal engines effectively, 2 x 3 cyl engines. And you know it right by the sound it makes. Those FH sound like something else.