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RE: MGB - possible Fuel injection - setups

To: "'ptegler@cablespeed'" <>,
Subject: RE: MGB - possible Fuel injection - setups
From: "Dodd, Kelvin" <>
Date: Fri, 8 Feb 2002 10:46:47 -0800
I prefer to learn.... hands on
> 'tis the fun of it.

                Here, here.  Can't let the home boys have all the fun with
their computer controlled econoboxes.

> Secondly.... porting and polishing a head is THE
> #one step in any performance upgrades. With no
> other mechanical system upgrades, you can easily
> gain 8-20% in power with a pro- p $ p job.
> The DYI'er first-timer could easily get 10%

        Minor disagreement.  The #1 step is to ensure that the fuel/air
mixture is correct for the required power band and the spark makes it go
boom at the right time.  Porting and polishing is great for upper end power,
but big ports can reduce torque at lower revs.

> With a properly p& p in place, FI will easily add 15-25%
> power increase in an older 'non-performance' designed
> engine.

        FI will only increase power if there was a problem with mixture in
the power band that your are concerned with.   FI allows greater control
over mixture, nothing else.

> So for the price of a straight up stock rebuild,
> you can assemble an FI system, clean up the ports,
> and add a conservative 15-20% power increase
> with good emissions, proper mpg economy, and much
> easier starting in any weather condition.

        This can only be done with a correctly matched system and loads of
dyno time, or very great luck.  Check out the Grassroots Motorsports article
on fuel injecting their rotary powered Spitfire.  Fuel mapping is like
setting up a Formula One race car, everything is adjustable and everything
needs to be adjusted, otherwise you end up worse off than with a stock
> Oh... and the web pages showing my route will be up
> soon.  :-)

        Cool, be looking for them.

> Paul Tegler

> > SDS specifically states that their ECU is not meant to work 
> with siamesed
> > heads, like MGs have.  I don't know the reasoning behind 
> it, but it is
> > clearly stated on SDS' website (

        I can see how electronic controls rely upon action/reaction for each
cylinder.  Lean mixture, squirt more fuel.  In a siamese or TB setup, there
is not a direct correlation for each cylinder.  Mixture is very much
dependent on flow speed through the manifold and head.  At high revs this is
not so much of a problem, but during transition and low rev pulling the
shared mixture is very variable due to intake and head design.  

> >
> > The other problem is that cost.  The SDS ECU is about $850, 
> add two to
> four
> > injectors, MAP sensor, 4 wire O2 sensor, fuel rail, hose, 
> throttle bodies
> > and TBS unit, wiring harnesses -- It would be hart to make 
> a profit even
> at
> > a $1500 selling price.  And also who ever makes the kit 
> would have to put
> > hours of dyno time into coming up with a suitable fuel map, 
> that the end
> > user doesn't have to play with so there is no chance of 
> them screwing it
> up.

        This is why TWM only sells the bits.  Tech service would be a
killer.  If you want to play, you pay.  Then you are pretty much on your

>  Now 20 years after 
> production there are
> > countless permutations of engine specifications, and I can 
> not see how it
> > would be possible to develop a map to suit them all. 

        Simple feedback loop, just like an SU.  Vacuum-fuel.  No Vacuum-no
fuel.  Installing fuel injection is very simple.  Optimising it for maximum
power takes lots of time/money/dyno.  The difference between carbs and EFI
is that you can adjust fueling without having to play with a pile of jets. 

 I am 
> of the opinion
> > that configuration of EFI settings from a laptop computer, 
> while on a dyno
> > or on a road course, is beyond the ability of the average 
> person on this
> > list.

        Just gotta steer with your knees.

> > Who is going to spend $1500 on EFI for their MGB, when a 
> new set of SU's
> is
> > 1/5 of that?  

        Only the lunatic fringe  (hand up in air)

SU's are fairly efficient, and quite 
> accurate... I think it
> > would be very difficult for a properly setup EFI to be 
> provide any better
> > fuel economy than SUs do (in excellent tune).  SUs can 
> adapt themselves
> > quite easily, with a different needle and a retune to many 
> parameters...
> if
> > you end up putting a new cam (of a different profile) in 
> your MGB, you're
> > going to end up remapping the entire EFI map.  

        And you are going to leave your SUs alone??   Methinks not, you are
going to find some guru who has some inkling of how much to buff off the
needle with emery cloth to increase richness at some lean spot in the power
curve.  More likely unburnt fuel will wash the oil off the rings and fill
the head with carbon.  With EFI, you can remap the entire system, not just
fire shots in the dark.

        Many good points made on both sides.  With the growth of street
racing, EFI component prices are dropping drastically.  The cross flow head
makes port injection a pretty easy task.  Crank fire ignition also solves
the distributor condition/accessibility problems in one swell foop.  I'm
interested in learning more, and am planning on putting something together
to play with in a spare chassis (in my copious spare time), just for fun.
There is just something about seeing how far the old B-series lump can go.
Calmer minds are likely to point out that a modern engine swap will be
simpler, but what does simple have to do with anything.  (besides my mind)

All the best


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