Kvach
My experience is all non-supercharged so far. But I can tell you that
there is a 'lot' of air being stuffed into a hood scoop, depending on
design, at 200 MPH, and very hard to equalize air flow, inside the scoop,
with an individual port Hilborn type injection. I didn't need a high speed
by-pass, heck I couldn't get it rich enough and maintain consistent plug
reading throughout the cylinders. Anyway I have the burned rear pistons to
back up my theories.
John Beckett, LSR #79
----- Original Message -----
From: "Butters Family" <bbutters@dmi.net>
To: <ardunbill@webtv.net>; <land-speed@autox.team.net>
Sent: Thursday, February 10, 2000 1:42 AM
Subject: Re: Tuning Mechanical Fuel Injection
> I have some questions on mech. FUEL INJECTION is there any
> relationship to high speed lean out and the forward faceing hat stuffing
air
> into the blower at 200+ mph. I guess you should know the answer to that
> question if it becomes more of a problem or only shows up on the track and
> not in the dyno room??? Has anyone used the conventional Hilborn type
> injection on thier blower to do say 90% of the fuel requirement and make
up
> the remaining 10% with electronic down injectors that is regulated wih
> O2 and EGT sensors. Seems like you woouldn't need those expensive high
flow
> electronic injectors and they could cycle better. Kvach
> ----- Original Message -----
> From: <ardunbill@webtv.net>
> To: <land-speed@autox.team.net>
> Sent: Tuesday, February 08, 2000 11:45 AM
> Subject: Tuning Mechanical Fuel Injection
>
>
> > Group, in looking more closely at the "Hemi Head Chevy Engine" article I
> > told you about earlier today, there is an illuminating technical tidbit
> > expressed for those like myself trying to get mechanical fuel injection
> > working properly.
> >
> > That's a sidebar in the article entitled "Iskenderian Dyno Report". The
> > chart under it reads in part as follows:
> >
> > RPM HP TORQUE BOOST BYPASS(jet)
> >
> > 5500 539 490 16# .105
> > 6000 578 482 17# .105
> > 6000 514 462 17# .090
> > 6000 590 492 17# .110
> > 6500 624 480 17# .110
> > 7200 638 440 19# .110
> >
> > All the above involves this hemi-head 301 Chev running on alcohol with a
> > 6-71 blower driven 1-1 with a Hilborn injector on top of it. With the
> > Hilborn bypass jet system, a smaller (numerical) jet size means a richer
> > mixture.
> >
> > Several interesting things here:
> >
> > l. The engine needed different bypass jet sizes to give max power at
> > different RPM ranges. Something about the cam timing, etc., was letting
> > more or less fuel escape out the exhaust at different rpms. Assuming the
> > Hilborn pump delivers a constant increase in flow directly proportional
> > to increase in rpm(does it?).
> >
> > 2. When running mechanical fuel injection, you can only run one bypass
> > jet during a pass on a speed trials course (despite availability of 'jet
> > selectors' etc., no time to turn 'em). One bypass jet size is not going
> > to give you full power at all rpm ranges, blown or unblown, so you will
> > have to focus on the top end and hope it doesn't hurt the mid-range too
> > much.
> >
> > 3. The blower's manifold pressure increased at the top end because the
> > gas-flow through the heads could not keep up with the increased output
> > of the blower. At 7200, even though the manifold pressure went up to
> > 19, the engine torque was dropping down sharply.
> >
> > The spark lead was 34 for all the above tests on this hemi-Chevy. The
> > heads had the plug electrodes at the combustion chamber surface(no
> > cartridge fire setup like the original Arduns).
> >
> > Any comment from veterans with mechanical fuel injection experience??
> > ArdunBill
> >
> >
>
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