This section exists
to help give back to the community by explaining some of the technical
challenges we've faced along with their solutions.
Valvesprings - we found the best valvetrain
stability during bench testing and in real-life applications
with beehive springs. We tested many spring designs in the 4g63
while developing this kit, including other beehives, while selecting
these as the best. We were the first to market with a beehive
spring kit for the4g63 and are in more 8-second cars than any
other spring out there. The same exact springs are used in both
our steel street and
titanium retainer high pressure
beehive spring kits. Cam-profile dependent, the high pressure
kit has been used beyond 11,000rpm and was stable on the bench
as high as we tested it, which was 12,600rpm. Sustained 11,000rpm
usage on the bench was dead stable, but the high sliding speeds
at the rocker to valve tip interface started causing some wear
and galling. To go this high, something like a DLC coating may
need to be employed.
Valve Float vs Boost -at very high boost levels,
more seat pressure is required due to mistimed pressure pulses
bouncing back off the valves and potentially popping them open.
This is highly dependent on each combination and setups that
breathe poorly seem to have worse problems. In general, about
95lbs on the seat seems to be good for about 45-50psi worst-case.
If you're going to be running more than this, you may need more
seat pressure. I have seen other similar engines that breathe
very well work fine with 45-50lbs on the seat for 40psi boost,
so it is highly dependent on the engine's pulse action and header/exhaust
tuning. The steel street springs are about 85lbs on the seat
and the titanium high pressure beehives are about 97lbs on the
seat. If you plan to go past 40psi for the steel streets or
50psi for the high pressure beehives, you may want to add some
shims. In drag racing applications we've had great luck shimming
down to 0.040" from coil bind at full lift (0.910"
min height, 0.870" bind) and still seeing great spring
life (no reduction).
©2011 Kiggly Racing, LLC
