07-01-2006, 08:45 PM
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CC Member
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Join Date: Nov 2003
Location: Dacula,
GA
Cobra Make, Engine: Porsche 928 S4
Posts: 408
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Not Ranked
Quote:
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Originally Posted by DavidNJ
Very interesting motor. What ECU are you using?
Curious, Ti valves, 7/16" pushrods, Jesel rockers with an Eagle crank and hydraulic roller. What lobes, cam timing, and valve springs are you using?
How did you decide on a Fluidamper rather than an ATI, BHJ, Rattler, etc.
Do you have suspension pictures?
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It has a Megasquirt II ECU with an LC-1 wideband O2 sensor.
The valvetrain is designed to be able to rev highly without heavy springs and corresponding worn and broken parts. The cam is a custom Comp grind with 240/244 duration @ .050. The roller lifters have been modified on an EDM machine with tiny oiling slots directing oil at the wheel which is an often overlooked detail. The travel of the lifters has been reduced to .030 to prevent collapsing at high rpms. From my younger days I remember valvetrain problems and still see it today in pushrod engines. A rocker arm mounted on a stud is inherantly unstable, it's like being at the top of a flag pole in that things will move, that's why it has Jesel shaft rockers. The accurate positioning of the rockers allows larger 7/16 pushrods to be used, they're the Comp Hi-tech ones which are the best possible IMO. The valves and retainers are titanium because that weight is even more critical than pushrod or lifters because the valve moves 1.7 times further than the lifter. The springs are Comp beehives, this motor has been to 7000 rpms with no signs of valve float.
The Fluidamper was chosen because of the viscous type design and I'm uneasy with a ring held on by a rubber bead. BTW, the zero balance Fluidamper was $400 and the rubber band types can be had for under $100.
I'll have to taks some suspension pics, stay tuned. 
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