[DML] Re: Performace fuel system
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[DML] Re: Performace fuel system

I'm not advocating using the K-jet, EFI, or any other particular 
course of action here, and I never tried the changes David is 
describing, but to answer John's questions, you need to add 2 MM to 
the shims to raise the fuel pressure by 10 PSI. The shims are simple 
flat metal washer-like things. They are small, but using one of the 
existing shims as a model any decent machine shop could quickly make 
just what you need for not too much money. You can also stack up 
shims to the desired height using "extra" shims from a dead unit if 
you had one.

As for test equipment, the results can be verified with a simple K-
jet fuel injection test set available from Warshawski or BMG, to 
name just two places.

The FV/lambda setup will return the fuel as John says, but that's 
exactly what you want under normal circumstances, and David's mods 
would provided added overhead for when you stand on it. I see no 
reason why the mods David described would not achieve the desired 
purpose because, as long as you didn't increase the fuel pressure 
too far, the FV would keep the mixture proper under normal driving 
demands while the extra fuel pressure would provide increase 
overhead for the more demanding driving scenarios. 

You might have to experiment a bit, but the theory seems perfectly 
sound to me and it really would not be hard or time consuming to 
try, either. Based on the mods this owner has already made, I think 
this is well within his ability.

I doubt that you'll need to modify the fuel distributor to keep up 
with the mods you have described. The stock unit will probably 
handle it. The way to find out for sure is to spend about $100 and 
an hour at a dyno shop to let them tell you what is actually going 
on right now with the car before you tackle any real or imaginary 
fuel delivery problems. There really is NO substitute for this!

Even if you find that you're a little lean at some parts of the 
curve, there are some inexpensive things you can do with the lambda 
system and/or the control pressure to flow more fuel without 
actually modifying the distributor itself.

One mod I would recommend if you make any of these changes is to 
upgrade to a heated lambda probe so that at idle the system stays in 
closed loop mode. Otherwise, the sensor could get cold, the system 
could go open-loop, and with the changes you made you might be 
running too rich at idle. This is also an easy upgrade.

Joe Kuchan

--- In dmcnews@xxxxxxxxxxxxxxx, "John Hervey" <john@...> wrote:
> David, Yes, And where are you going to get the shims and what size 
how are
> you going to get and how are the test results with out the 
equipment and
> when do you know when its to much or how much. 
> Then what are you going to do about fuel going back to the tank 
now that you
> have increased fuel flow. The FV is going to get rid of it because 
there is
> more. So the purpose is defeated via the FV / Lambda system. 
> The injectors are fine as they are it's the FD that has to be 
modified to
> gain the results that are needed.
> John Hervey
> www.specialtauto.com
> -----Original Message-----
> From: dmcnews@xxxxxxxxxxxxxxx [mailto:dmcnews@xxxxxxxxxxxxxxx] On 
Behalf Of
> David Teitelbaum
> Sent: Tuesday, March 27, 2007 7:51 AM
> To: dmcnews@xxxxxxxxxxxxxxx
> Subject: [DML] Re: Performace fuel system
> By shimming the spring on the Primary Pressure Regulator you can
> increase the pressure a little which would increase fuel flow. I 
> it isn't much but it IS one of the tweaks that can be done to 
> fuel delivery. Other more radical mods would be to change the 
> or the plunger inside the fuel distributer or even changing it to a
> model that flows more fuel. Changing the injectors could also help 
> necessary. The main problem is it is a mechanical system. To make
> tuning changes you have to either modify or replace actual parts. 
> is the most impressive feature of an EFI. You can adjust it all 
> of ways without even getting your hands dirty!
> David Teitelbaum
> vin 10757
> [long quote trimmed by moderator]

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