Quote:
Originally Posted by Tim Radley
Piston to valve clearance is tightest at lower lift not higher lift.
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Yep, that's why I said I wrote all else being equal.
Quote:
Originally Posted by Tim Radley
Adding 1mm of lift to a cam profile doesn't mean you need 1mm deeper pockets cutting in the pistons.
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I didn't say that, that is your assumption/speculation.
Quote:
Originally Posted by Tim Radley
A 13mm lift with 240 duration will likely have a lot more piston to valve clearance than an 11mm lift with 280 duration.
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That is an opinion and I can respect that. However, a 280 duration 11 mm lobe may have more clearance than the 13mm - 240 degrees one depending on how the ramps are ground.
And to widen the discussion, the camshaft choice for the FA20 is not an easy topic.
"Hot" cams today are not what they used to be and that is the main reason we don't see many of them on the market.
It is quite important for every enthusiast to understand that cams are merely valve timing tools. In the pre-variable valve timing era, cams could alter the valve timing events to suit the needs of the driver.
This doesn't apply directly today since there solenoids that already alter the timing event based on input from various sensors across the car.
I cannot stress this enough, changing cams on the FA20 is not the same as it was 20 years ago on a simple DOHC multi-valve performance engine.
Regarding valve lift, increasing it will allow the engine to breathe better at the upper part of the rev range or perhaps beyond the stock rev limit. In most engines, lift is not a bottle neck for the 19/20's of the stock rev range and increasing it may hurt air speed at mid/low range. Careful consideration, planning and reading is required, engine tuning is not easy but its a lot of fun.
Cheers
