ox sensor on sequential efi,high overlap cam....

[Jemison Richard]

Tom,

Sorry for the confusion.  We're on the same page.

> -----Original Message-----
> From:	Tom Sharpe [SMTP:twsharpe at mtco.com]
> Sent:	Wednesday, December 02, 1998 1:48 PM
> To:	diy_efi at efi332.eng.ohio-state.edu
> Subject:	Re: ox sensor on sequential efi,high overlap cam....
> 
> 
> 
> Jemison Richard wrote:
> <snip>
> 
> >         [Jemison Richard]  Turbos actually do care I believe.  Most
> turbo
> > cams are wide center line, mild duration, moderate to high lift cams.
> You
> > don't want to lose all that pressure out the exhaust pipe!  Also,
> cylinder
> > filling is largely taken care of my the pressure developed by the turbo.
> So
> > you don't need cylinder scavenging.  You already have a large pressure
> > differential across the cylinder to remove combustion gases and recharge
> the
> > cylinder.
> >
> >          Also,  grab your favorite cam grinders spec sheets or catalog
> and
> > compare hot street and turbo cams and check me out on this.
> >
> >         Rick
> 
> Two points, Removing the combustion gasses is a problem with Turbo motors
> as the
> exhaust pressure can be higher than the intake. They take a standard, mild
> cam
> and crutch the exhaust by openning it sooner; more time to blow down. Net
> result
> is wider CL.
	[Jemison Richard]  Got a megacycle cams sheet in front of me for 750
Honda (sorry this is the only one I have right now but for reference they
list a high perf street cam with I/E order  Lift  .400 / .375   dur at .04
262/257  Centerline  105.104.5
	their turbo cam for same bike
Lift  .342 / .312   dur at .04  215/222  Centerline   106/106

	This is fairly typical.  That was my point.  Less lift - I agree
earlier exhaust opening but not a whole lot -  very conservative durations
and wider centerline (less overlap).

> You're right though, boost is better than lotts of cam and RPM, but a
> turbo at
> high rpm will still need a big cam thou not as big as a na motor.
> 
> My point was (originally), that we should tune the idle by driveability
> and
> 'dead recon' the idle mixture from there and forget all that learning
> stuff (at
> idle). Just use the O2 for a reference. That assumes that we can easily
> change
> the map and have a good trimmer for the map sensor.
> 
> My 482 idled like a kitten with a Predator carb, alcohol, and roller
> cam..... it
> just dribbled raw fuel out of the headers at idle, not enough to clean the
> floor, but almost. (another sick try at humor).
	[Jemison Richard]  Yea, the roller cam does wonders for idle
quality.  I never had problems with the fuel literally running down the
pipes but the low end mixture was major goofy. 


> later  Tom
>