can it be over 100% for normally aspirated engine? (I've read that by careful design of valve timing it can but onoy over a limited range).
anyone confirm or otherwise, perhaps with linky to web site that discusses this?
ta.
Look up "pulse tuning"
or read
http://www.pumaracing.co.uk/power2.htm
EDIT: er yes it can be over 100%
[Edited on 19/9/06 by clockwork]
perfect!! thanks.
yes, it can, as no doubt explained by Dave Baker in the article above.
Volumetric efficiency is the amount of air that gets into the cylinders compared with the volume of the cylinder. Because there is a slight vacuum in
the inlet manifold, volumetric efficiency is usually less than 100%
Engines are designed with valve overlap. The speed of the exhaust gases would create a partial vacuum in the exhaust manifold if there was no
overlap. instead, this "suction" helps draw in a fresh charge. The same applies to the inlet valve timing. the valves can be timed to
close just after BDC. this allows the inlet air velocity to force a little bit more in before the valves close. Add a bit of ram air and you might
just squeek over 100% volumetric efficiency. Or you could fit a turbo.
And if you're talking about filling in the table for an FI system then unless your req_fuel (as it's called in Megasquirt) is spot on then your VEs in the table may be well above or below the genuine value being acheived.
yes its all in the pulse tuning to do with intake and exhaust length. look for previous threads on this subject
quote:
Originally posted by matt_claydon
And if you're talking about filling in the table for an FI system then unless your req_fuel (as it's called in Megasquirt) is spot on then your VEs in the table may be well above or below the genuine value being acheived.