RE: [T3] Hopping up, keeping FI

["Mark Davis" <m37davis@adelphia.net>]

Here is a good page about F.I. D-Jet. I have a note written on my copy of
that page about adding a 275ohm resistor from the head Temp sensor to the
wire in the harness it came from. I have not tried this. I was gathering
information to do the same thing you are writing about. You could also use a
500ohm Pot. In the same location instead of the fixed value resistor to
enable fine tuning of the fuel/air ratio.

http://retro.co.za/efi/d-jet.html

Hope this is helpful, as I said I have not tried it. I have become
physically disabled and have not been able to put my car back together.
Still looking for someone capable in my area. Good luck and please let us
know of your success or lack thereof. 

-----Original Message-----
From: Keith Park [mailto:topnotch@nycap.rr.com] 
Sent: Friday, April 22, 2005 9:08 PM
To: type3@vwtype3.org
Subject: Re: [T3] Hopping up, keeping FI

Yes, to a degree.  Lumpy cams tend to have an issue with the pressure
sensors though.  Yes, the systems compensate to a point... but that point
can be extended out by increasing the fuel pressure which enrichens the
entire mixture curve evenly.
>
> Can you hop up motor and still run the FI?  I've fallen in love with the
FI
> on my son's '69SB and want to keep it on my car.  As I understand the FI,
it
> is working mainly on the manifold pressure.  This seems to be based on the
> idea that the manifold pressure would exactly relate to actual volume of
air
> passing throught the intake tubes.   So. . . it seems that if I added
large
> valve, hi flow heads and a mildish cam to take advantage of the flow, the
FI
> system would compensate and continue to add in just the right amount of
> fuel.  The BMEP would stay the same, only at higher RPM's, thus giving
more
> power.



> I guess the specific questions would be:
>
> 1. If I keep the displacement the same, can I add a mild cam (275-285
> degrees, like in a Porsche 912) and hi flow heads with the same
compression
> ratio, will the FI work?  Target red line would be about 5200 rpm.

Mild cam should be OK, Youll have to noodle with the injection a bit but the
stock system should do it.


>
> 2.  What happens if I increase compression, or achieve the same result by
> ceramic coating piston domes and combustion chambers?

Increased compression makes the motor run hotter... and your limited by the
Type 3 cooling system unless you start doing some really fancy things.
Anyone heard from Shad Laws lately?  he'd have some infor on coated pistons
and compression chambers,  maybe Jim A will chime in here too.
>
> 3.  Will the FI work with an increase in displacement?

Up to about 1800 or 1900 cc no problem, just increase the fuel pressure.
>
> 4.  I see two easy ways to make adjustments to the FI, by fooling with the
> Pressure sensor, and with the fuel pressure regulator.  Upping the fuel
> pressure would seem to richen the whole range from idle to WOT.  I'm not
> exactly sure how fooling with the Press sensor would affect things.

Yes, but the pressure sensor ISNT easy to simple adjust... there is alot of
info out there as to how they are built and how they work.  Learn learn
learn before you start adjusting it or you are likely to end up with a
sensor that is defunct.
>
> 5.  I remember reading at some point in the  past that there was a company
> somewhere on the west coast that could rebuild the ECU, onyone know who
that
> was and if they are still around?

Not aware of any
>
> Any comments or experience about this would be greatly appreciated.  I
know,
> it sounds like I wanna be a darksider and not, like having my cake and
> eating it too.  :o)

Here is another idea... if you go 1.9 or 2L get a stock 2L injection system
off a 914 Porche with the larger injectors and it is going to be a closer
match to the bigger engine your building.  OR get really dark (have I spent
too much time breathing parts washer fumes tonight?) and fit an L jet system
to it and have more tuning options and a more advanced system....

Keith

>


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