[bazza]

Originally Posted by oab_au

Gee Bazza, I can see that you are determined to go your way, so I won't deter you., but there are a few things that need to be straightened out.

The EZ30R runs 10mm lift on solids, this is common on a lot of production engines, not really a race motor.

Indeed they do but you miss my point. The EG33 came out of the factory with valves, guides, cams, springs and rocker covers all designed and engineered to run with the sub 8 mm lift. The EZ30R was designed in the factory to run 10mm lift. Making an EG33 run >10 mm lift and be very reliable with minimal maintainence was something we were not interested in having to R&D. The amount of effort required to get the big lift cams working far out weighs the benefits for a turbocharged EG.

I can see that you don't understand the benefits of big lift.

You say that the flow bench shows that 9mm is really the maximum lift for flow. That is when the area of the open valve matches or exceeds the valve throat area, and the throat dia is limiting the flow. What the flow bench does not show is how much, when, and for how long.

I do understand them (at a basic level) but you're trying to over engineer something that doesn't require it. If we can push the billet or reground cams to 7000-8000 rpm and make 300-400 kw atw and have the engine pull to redline with ~9mm lift then it's a great win. The cost for me is < $400 to do this to the cams. Stuffing around with bigger lift will require a valve train upgrade - springs, retainers, valves, buckets and a lot of custom work plus increased maintenance etc etc. We're talking $2K to do it AND for what real benefit?

If you use 9mm, you are getting the maximum flow at maximum opening point, for maybe 10/15* but each side of that it is not maximum. it is either opening or closing, and port flow is at less than max.

This is a diagram of two 240* profiles, one at 9mm and one at 12 mm

You can see that the line at 9mm shows the max port flow, which the 9mm lift cam just reaches, for 10/15*. The 12mm lift cam reached the 9mm max port flow early, and it maintains max port flow right through max lift, till the valve has closed down to the 9mm lift point, almost 90* of max port flowing air into the cylinder. This is the benifit of using the higher lift.

You also say " massive duration ", massive duration is for massive rpms, but you are only reving to 7000, the standard duration will cover that speed without any loss of torque spread.

Harvey.

I agree with what you're saying but again why over engineer something? A previous engine combination in my car was 272 cams with 230 @ 50 thou. 10.5 / 11.5 mm lift or thereabouts and it had both insane midrange and revved beautifully. Reducing the lift will reduce the low end torque will it not? It's a turbo 3.3L... I can live with that given it should be between 4500-7000 rpm at the track and lack of torque is easily fixed if required with increased boost.