Mk3 Interceptor: This is my 440 EFI conversion log.

[Philip Lochner]

Philip,
A 7/16" Dia hole, unblocked , will support a 572cuin motor at idle. Glad to hear you found the problem! Im not sure how well your motor will tune without running it in speed density mode. Why the decision to go alpha N? Even the most radical builds (like Joerg's ) use a MAP for precise volumetric calculations. Map port placement/design can be a science unto itself on some intakes! I guess your transient fueling is dTPS only. That's kind of tough as it wont pull fuel at decel.

Hi Bruce

This TB has a 12.5mm (1/2") port for idle air in addition to the 9.5mm(3/8") hole for the PCV intake, but now that they work, they are adequate indeed.

Somewhere you must have arrived at the wrong conclusion as I AM indeed running speed density (NOT alpha-N). You are right with the MAP port placement. On this setup the port placement does not work well either as my MAP figures are jumping quite a bit so I will be investigating another point like directly on the plenum.

Transient fuelling is dTPS only (TPSdot in MS speak) but it also offers a feature of fuel reduction on decel (and complete fuel cut).

[Philip Lochner]

Right, getting there now....

I had fuel starvation issues. It turned out that the EFI pump in the surge tank was pumping out fuel faster than what the lift pump could supply it to the surge tank.

This morning, I repositioned the fuel return line from the engine (it fed back into the main tank before) to T into the line that feeds fuel to the surge tank . This means that a lot of fuel is being circulated to the engine from the surge tank and straight back to the surge tank via the fuel pressure regulator which results in the fuel being heated up when passing through the engine bay. Now the lift pump only has to supply the fuel being consumed by the engine which is much less than before, and now the surge tank remains filled most of the time.

At the end of a rather long drive this afternoon with ambient temps around 28ºC, the fuel temp in the surge tank was at 44ºC when I got back home. (I was expecting it to be much higher).

I find that I now have more "time" to just enjoy the new character of the engine and I'm thoroughly enjoying it.

Throttle response is much more aggressive. Whilst I'ld like to ascribe this fully to the EFI conversion, I should mention that the throttles on the Edelbrock TB is now of equal size, thus the primary barrels can already pass more air than the TQ carb primaries and also the rate of throttle opening on the Edelbrock is faster than was the case with the carb, so this could also contribute to the responsiveness that I feel.

Nice, nice, nice

[Philip Lochner]

Now that the physical path for idle air via the idle valve is open, (having drilled the required holes into the manifold from the ports on the idle valve), I re-installed the PWM (Pulse Width Modulation) Idle valve that came with the Edelbrock Throttle body.

Now it works as advertised. I thus retract any unflattering remarks I may have made towards the product. The nice thing now is that I don't have to do additional plumbing to get clean air to the idle valve. Still have to get clean air to the PCV intake though.

I find that with a duty cycle of about 55% the valve is pretty much open and at about 20% it closed. I suspect these values would change depending on the extent by which the primary throttles are cracked open with the throttle stop screw. I'm driving it at about 210Hz at present.

[Philip Lochner]

Right, so this then, is pretty much the final "product":










Now I just want to replace the "tok-o-tok-o-tok-o..." facet fuel lift pump with a roller cell pump that would make a sound more comparable with an EFI car, then this EFI conversion is just about done. I can hardly believe that its come this far.... but very happy.

[DaveAK]

Great job Philip! You should be happy!!

[Philip Lochner]

Thanks Dave! Very pleased indeed!! Nice to be sharing the moment with like minded folk.

If my neighbour did not have small children I would take the car for a drive right now, but starting this beast now will wake up the entire neighbourhood!!

[DaveAK]

Thanks Dave! Very pleased indeed!! Nice to be sharing the moment with like minded folk.

If my neighbour did not have small children I would take the car for a drive right now, but starting this beast now will wake up the entire neighbourhood!!

Offer to take them along for the ride!

[Joerg]

Great job - I still have some way to go.
I?m always amazed how much pipes, wires and other stuff is under an Interceptor bonnet.
Will try to avoid that on my build.



Joerg

[bkbridges]

Beautiful plumbing!
BKB

[Joerg]

Thanks. Was a lot of welding, grinding and bending. Vacuum pipes was more than 2.3 meter alone (see picture further above). Catch tank is a modified little pressure vessel. All done in stainless steel and shotblast afterwards and then clear coated.

[Philip Lochner]

It is good practice to have a stable voltage supply on a car fitted with EFI. Until today, the output voltage on my car's original Chrysler alternator was not as stable as I wanted, because the regulator regulated the voltage in a very crude manner (electronic, but behaving similar to the original relay style unit) which resulted in the voltage jumping up and down by about 0.7V.

Today I fitted an ADJUSTABLE voltage regulator and now the output voltage is stable around 14V. More here: http://www.joc.org.uk/phpBB2/viewtopic.php?f=4&t=16076

[Philip Lochner]

Recently, friends of mine converted an old Range Rover Classic (which received a 4.6 upgrade) to EFI. This car had a strange thing where it would just inexplicably run out of power at around 3500 rpm. Long story short, they eventually found that there was some resonance in the fuel rail where the frequency of injections somehow were out of phase with pulses from the fuel pump rendering actual fuel delivery almost nil. This problem was "found" quite by chance!!

Now, I've had a strange thing on the Jensen where, at around 2200 rpm, the fuel map suddenly called for substantial increases in fuel and I found it near impossible to get leanish mixtures at this point. I've always thought that the intake manifold just suddenly starts working very efficiently at this point but now I'm thinking that I've got similar "fuel pulsing" issues in my car.

As part of the 4L60e 4-sp auto conversion (http://www.joc.org.uk/phpBB2/viewtopic.php?f=4&t=17192), I intend changing the fuel pump to that of a Land Rover Discovery 2 V8 (which has an integrated fuel pressure regulator) and has a single line feed to the engine. This has the added benefit that fuel going to the engine never returns to the fuel tank or the surge tank, thus keeping the fuel in these tanks at ambient temp. I found on extended drives that the fuel temp in the surge tank (which received the fuel returned from the engine) became hot and this caused the fuel pump to become much more audible, and leaving me concerned about the pump's longevity.

[Philip Lochner]

I'm still having the problem of fuel in the surge tank heating up and hearing the EFI pump complaining when that happens, I HAVE to find a solution to the fuel heating issue.

Last week I tried a non-return fuel supply SIMILAR (ie not the same) to what my LR Discovery 2 V8 has, by moving the fuel pressure regulator (FPR) to the boot right after the EFI pump output with the fuel return from the FPR directly back into the surge tank. This was a very disappointing failure. At light throttle the car would develop a lean surge, but at wide throttle it was quite ok. I suspect this was a combination of all the parts in the system, so I promptly changed the fuel supply back to the fuel return as it was, with the FPR directly after the fuel rail. My setup did differ from the LR setup in ways that could matter so I might still try the LR pump at some time for a non-return setup (which remains by far the most elegant solution). Physical mounting of the LR pump in the Jensen will be quite a challenge (its huge).

My Jag V12s use a "fuel cooler" which is part of the AC system and uses the spent AC gas to cool the fuel down before returning it to the fuel tank. (Clearly they had the same problem...) This however, requires the AC compressor to run in order to work.

Having the fuel rails enamel coated (like they do on turbos and high end performance manifolds) and covering the fuel rails with heat insulation are also options. Another option is installing an "oil cooler" but run the return fuel through it first.

Any other ideas?

[Steve Payne]

I had exactly the same problem originally and I even had a hot petrol tank a couple of times

In the end I plumbed it differently and believe it or not a smaller pump to feed the swirl pot.

I picked this hint up from a forum in the US where there a few people having similar problems.

You need to plumb the swirl pot as follows.

Feed the pump for the injection from the bottom, next one up is the return from the injection, next up is the new fuel from the fuel tank and finally the top connection returns to the main fuel tank.

I am using a Facet style fuel pump that runs 120ltr an hour at 4 to 6 psi. My Swirl pot is 1ltr and in 60,000 miles I have never run out of fuel. My guess with no restriction the fuel pump is probably flowing better than its specification and with the return from the injection helping keep the swirl pot topped up.

I tried a fuel cooler with a fan, it didnt work just added more complication to the system.

Steve

[Philip Lochner]

You need to plumb the swirl pot as follows.

Feed the pump for the injection from the bottom, next one up is the return from the injection, next up is the new fuel from the fuel tank and finally the top connection returns to the main fuel tank.

Sorry Steve, I can not visualise the above.

I know its effort, but could you do a drawing (by hand is good enough) please ?