Injection timing, electro valves &c.

[Kalle Pihlajasaari]

Hi All,

> > > As I understand it, it is best to inject the fuel after the intake valve
> > > closes, so the fuel vaporizes on the somewhat hot cylinder head
> > > surfaces.  Is this true?  Is there any advantage to injecting at other
> > > times during the cycle?  If so, explain the reasoning.
> > 
> > Yes, please do.  Grumpy Jenkins said in his book that 85% of the fuel
> > vaporization occurs in the cylinder.  'Couse he's talking race
> > engines versus whatever we're running (street / HiPo / semi-race /
> > whatever).  It would be nice to know what the current state-of the
> > art is.
> > 
> Maybe it is not important as the Fuel gets squirted in\
> but when i ran my 4 cvl 2litre race engine on 50mm throttle bodies the
> air spedd was so low i lost 25kwatts of power compared to 45mm ones. has
> to do with taper as well as venturi effect

In a similar vein.

Could one not somehow measure the air charge in a cylinder by measuring
the conrod compression or someother thing like a genuine pressure
sensor in the actual cylinder.  Then it would no longer matter how the
ait got in the cylinder the temp would be close to constant at near
max compression (correct for fuel load) and then you wuold know one
cycle later what to inject for the next air load.

This would mean there would be no gadgets in the inlet except for the 
bytterfly.  No temp, no pressure, no flow, no venturi, and such.

Now onto the like-wow electro valve head, you would then need no butterfly
as you just close the valve early if you want less air.  I want one of
these engines as it will be the first real major change in IC engines in 
a very long time.

With direct (in the cylinder) fuel injection one can already get rid of
the inlet cam by just using a set or reed valves and suck in the air
and then only inject if you want to with power controlled by the
ignition timing and the number of cylinders to fire.  To be fair
this is essentially what 2 stroke engines do at the moment but they
still use the 'carb' and could eliminate this as well if they only 
metered the fuel and not the air.

Cheers
-- 
Kalle Pihlajasaari     kalle at ip.co.za
Interface Products     P O Box 15775, DOORNFONTEIN, 2028, South Africa
+ 27 (11) 402-7750     Fax: 402-7751