techie engine topic

[jeff miles]

do any of you guys know what the manifold depression (vacuum) is (lbs sq in or whatever)for a 4L RV8? I am trying to find the range from tickover, thru constant cruise, to throttle wide open under full load. And if you do know, do you also know where I can get an adjustable pressure/vacuum switch that will work in that range.

Thanks

jeff

[tvrgit]

can't speak for Rv8 specifically, but most engines have vaccuum of about 21 inches of mercury at (fast)idle, dropping to 2 or 3 inches at full throttle. Max will be about 27" on over-run.

I'm intrigued - what do you want this pressure switch to do?

[jeff miles]

tvrgit

thanks for that - I'll get out the fiddlestick and convert to bars or whatever they use these days.

Why - switch controls solenoid for methanol/water injection (misting) - not happy that the existing switch controls the dosing well enough. benefits are cooler, denser charge with modest gains in torque/power and a 'happier' donkey - fitted together with ACT induction pipes. The real purpose is in preparation of the induction side for later head upgrades and higher compression ratio. The methanol mixture, even in modest amounts, improves the octane rating of the combustion mixture enabling use of ordinary unleaded pump gas. The forced induction guys use it regularly - not much use on smaller normally aspirated engines, but useful on a big, hot, hard worked V8! A bit more giggle for a modest outlay


Cheers
'owdgit'

[Boosted LS1]

Vacuum will drop to zero at full throttle, mine did just before it went on to pressure

At idle I had 19/20 odd hg's.

Boosted