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Theory question. For info-discussion reasons only.
I installed the green whites (thanx TRS) and like the consistency they created even at my relatively low 5 to 6 thousand ft.
Many seem to be popping these in so why?
Poo has them in stock but spec the sled with very stiff springs. Cylinder pressure is required to open the valves. Increases in elevation, worn rings, low rpm, all lower cylinder pressure.
Is there always enough pressure to overcome any spring?
Theoretically if a valve hangs closed too long it increases air flow there and may create a lean or even det condition. Worse case scenario is the valve does not open at all. We all know that would mean less power at high rpm.
In reverse if too soft a spring is selected (doesn't close maybe because of carbon build up) the worse case scenario is lost mid range or rich bog.
Why, theoretically, does Poo spec these springs? They know this stuff too and must realize the sled is headed for elevation. Doo has spec'ed stiff springs but on carbed models so there was some built in correction for air velocity (carbs work on intake velocity). No air correction factor in the Poo injection system.
If the valve opens when the solenoid dictates (theoretically) what does a spring change do? This valve opening is timed with some important engine management adjustments by the 'putor too.
What do you think is happening when you install a softer exhaust spring? What have you "felt"?
I was having a lot of chatter from the valves last season. Put in green/white springs and we'll see how that goes. 14.1 DI, slp pipe and can, PCV riding 8k+.
What do you think is happening when you install a softer exhaust spring? What have you "felt"?
The valves open sooner and stay open longer. If you run an aftermarket exhaust, you darn well better be running softer springs to prevent heat build around the exhaust ports! Just read your egt's and that's all you'll need to know. Porting requires more air flow and softer springs too. Something I learned real fast with funky noises coming from my Union Bay motor (sounds like someone shuffling cards if your exhaust valves are not opening soon enough). Also the higher the altitude, the lower the spring pressure. UBR didn't run any springs in a lot of their hillclimb sleds.
Have FUN!
G MAN
TRS - what do you recommend for myself and G-Force? Different elevations but we are both curious... thanks!