Originally Posted by shlammed
I will take 100 custom cam sets. But i need help determining if the VVT will be able to handle larger cams. (think s14 sr20det... they cant handle large duration cams because of some sort of wizardry)
Looking at a number of places for fragment of information (not just facts, I try to learn the concepts and pitfalls also) there seem to be a number of different aspects.
The biggest one is that to sell an off the shelf upgrade in the US, some seems to only want to sell "lawyer proof" products.
If you increase the duration of a VVT cam on a interference engine you will need to take care. Either reduce the cam movement or make larger valve pockets in the pistons. Both of these is not that shade-tree applicable.
The Miata VVT have 47 crank degree sweep and is 50 degrees into lift at TDC (stock duration, max advance) and have reached half max lift. Add 1mm lift and you need to deal with it.
The tougher issue comes if the VVT can't handle larger valve-spring pressures (can't reach target advance, flops around under spring control), which means that you cannot user steep ramps and you are left with a pointy cam (not as meaty and "square" as you would use for fixed timing), since you are forced to use soft springs to not screw up the VVT.
I hope that the Miata VVT can be used with a bigger cam/tougher springs and can control the advance (full retard is not terrible as a last resort).
Ti Retainers could be a tip though and the Supertech SUBs seems to be a few grams lighter than the MazdaSpeed ones, this and springs on the lighter side (maybe more preload than rate to improve seating but not ramp up the whole force that much?)
I hope it will work. 8krpm without problems would be nice
(even though I'm only looking at 7.5 as limit in our regulation).