[Diy_efi] sequential injection timing

[Mark Claywell]

> > Talk to someone who is running a racing engine and not a street engine.
> 
> Ya dem 10 sec GNs prowling the streets are a bad example of hipo street
> engine.

Just because they are fast doesn't mean they couldn't be marginally faster.
With all due 
respect, I don't consider most of these street drag cars a race engine. 

> Once you cross more then about 25% DC the whole issue is mute.  The only
> place you see any gains with SEFI in a racing engine is when your out of
min
> operating time for idle.   And even then a double/dual batch fire works
just
> as well.

I'd have to say that when you go to much higher injection pressures and get
lower SMD that EOI can become a larger issue. Of 
course most people will say that 2-3% gains is small potatoes. For race
applications 2-3% is signifigant. I'd say that your right, most of the
times a batch fire system will be just as good. But like I've said it is
engine and injector setup dependant. Over time I have learned the hard way
that there are not
many generalities that can be made about intake/engine system design. 

> Just out of curiousty have you actually scoped a japanese engine and seen
> that it was firing at an open intake valve?.

Whoops. That actually should have said '4 banger japanese Motorcycle
engine". I must admit that almost all of the 
tuning that I have ever done is on steady state dynos. I use the
track/street for mapping some of 
the transient fueling issues. I think that may explain some of our
difference in opinion on injection timing and it's effects. Yes, I have
seen that injecting on a open valve can provide about a 3% gain in torque
output for just changing EOI. The dyno I used was controlled for water
temperature. During EOI tuning lambda is held constant. This was on
gasoline. Most of the time was spent tuning EOI for high loads (ie - above
75%). I have seen larger gains while using alcohol fuels. The main reason
for a gain in VE is that you are carrying more fuel as liquid instead of as
a gas, with the liquid taking up less volume. Also, the fuel cools the
charge in the cylinder. 

I have a friend with a 87 turbo Supra, and I know he was playing around
with EOI timing for more power. He was heading towards lower EOI (in deg. 
BTDC comp.). However, I think he was running a race gas at the time, and
that might make a difference.

mark



> Bruce
> 
> 
> 
> 
> > > Bruce
> > >
> > >
> > > ----- Original Message -----
> > > From: <Djfreggens at aol.com>
> > > To: <diy_efi at diy-efi.org>
> > > Sent: Tuesday, July 30, 2002 10:29 AM
> > > Subject: Re: [Diy_efi] sequential injection timing
> > >
> > >
> > > im not a EFI guru but the obeject is the same as in a carberator.
> > sheerin=
> > > g
> > > the fuel into vapor. most likely the best way to do this is to create
a
> > 9=
> > > 0=B0
> > > angle to airflow. keeping the injector close to the vavle is crucial
for
> > > good
> > > dry flow chareteristics but its not nearly as importnat as sheering
the
> > f=
> > > uel
> > > into vapor. the optimum placemnt for the injector would be right
before
> > t=
> > > he
> > > short side radious in the intake port. and the timing would have it
> > squir=
> > > t
> > > right as the valve began to open. thats my 2cents.
> 
> 
> 
> _______________________________________________
> Diy_efi mailing list
> Diy_efi at diy-efi.org
> http://www.diy-efi.org/mailman/listinfo/diy_efi
> 



_______________________________________________
Diy_efi mailing list
Diy_efi at diy-efi.org
http://www.diy-efi.org/mailman/listinfo/diy_efi