Thread: efi on a p76 donk

Just to add my 2 cents worth to this old thread.....

I built a P76 engine with '86 Rangie heads and EFI. I was running it on petrol, but this I thought this info might be usefull to someone find the thread.

I used the standard Rangie flapper flow meter, and tuned it by prising off the cover to the flapper valve and adjusting the calibration of the variable resistor inside. The lid is stuck on with an adhesive and can be removed if you carefully prise around it, like removing the lid of a paint can. I made a spring clip out of a bit of clothes hanger to hold it on while I was going through the tuning process.

There is an arm that is attached to the flap that sweeps along a resistor track. The resistance value tells the ECU how much airflow is detected so that it can send the correct signals to the injectors for that flow. This can be adjusted in increments to change the relationship of the arm to the flap, thereby richening or leaning the mixture. By playing with this I had no problems getting the mixture correct. The engine would run smoothly from 500 - 5000+ RPM. I fitted an adjustable fuel pressure regulator but did not find it helped. The injectors had no problems coping with the fuel flow. I got better economy with the 4.4 than I did with the 3.5.

The only problem I had was with the advance curve in the dissy, which needed adjusting for the bigger engines characteristics. It would ping at high revs & full throttle sometimes.

Buncha

Originally Posted by GuyG

Post 1:

G'day Guy
I fitted a P76 4.4 motor to my 88 EFI (flapper type) Rangie about 3 years or so back. I'll share my expereiences with you so you know that it is not the simplest of things to do- this may turn out to be a long post.
I got the adapters from Dave at Rovacentre. For the 3.5, they are flat plates 19mm thick that bolt to the block over the top of the valley cover with allen head bolts recessed into the plates, the inlet manifold then bolts to the adaptor plates using the original bolts. The plates are not angled- all the Rover blocks have the same V angle of 45 degrees- the longer stroke of the 4.4 (19mm longer than the 3.5) means that the heads end up further apart. The ports in the plates are huge compared to those in the heads and manifold- I borrowed a die-grinder and matched the ports to the plates (this necessitated porting the valleycover as well), then used locating pins to ensure that everything seated in the matched position. This was a fair job in itself.
You need to make gaskets for the spacer-to-manifold joint. I ended up with vacuum leaks here- the bolts that hold the spacers to the heads are well off centre in the plates, I think the bolt arrangement results in less than optimal seating of the plates. When I removed everything to repair the leak, I stripped all the paper gasket off my tin valley cover and used Z-bond sealant instead of gaskets at all the inlet joints, including both surfaces of the valley cover. No more vac leaks.
Anything that bolts to both the block and the heads needs to be lengthened by 19mm- I remember extending the power steering pump bracket, don't remember if there was anything else. The engine mount brackets have to be modified by cutting, drilling and welding. You need a longer power steering belt, also longer aircon belt.
There is an adaptor for the rear of the crankshaft- simple enough to fit up. I had the motor out twice to replace the rear main seal- the black ones that come in gasket sets (even good quality gasket sets) are useless- make sure your motor has one of the good quality red seals in it before you fit it.
I managed to bend my exhaust system to fit the wider (and higher) position of the manifolds by hand in a vice, took a few goes in and out to get it right.
Once you have everything fitted and modified, the real difficulties start. I'm not sure about going from a 3.9 to 4.4, but going from a 3.5 to 4.4 meant that the injection system could not provide enough fuel for correct mixture under load or at high revs. The standard system simply will not provide enough duty cycle length to the injectors to run the bigger engine, resulting in dangerously lean mixtures under load. I was ill-advised to have a 'UNICHIP' system fitted. The unichip agent spent many hours stuffing around with the thing over a period of about 2 months, and on my last visit to him told me that he was closing down his business- with my car still not running right. I went to another UNICHIP agent about 1 1/2 hours drive from home(only their agents have the tuning software) who charged me about $250 to tune the car- when I picked it up from him it backfired constantly on overrun, then broke down half way home. I removed the UNICHIP and replaced all the butchered wiring from it's installation. $1300 down the drain, plus one muffler and 2 airflow meters destroyed by backfiring due to the way the unichip agent had wired the system, plus $250 for a rising-rate fuel pressure reg to try to increase the fuel feed (don't let anyone try to convince you that this will help). The unichip agent tried to tell me I needed bigger injectors- $200 each. Eight of them.
I ended up removing the airflow meter, ECU and all the wiring from the fuel system and fitting an aftermarket system (SDS- 'simple digital systems' from Canada) that utilises the original fuel pump, filter, lines, reg, TPS, piping and injectors with the addition of a MAP and inlet temp sensor and a fully user-programmable ECU. Also fitted a mixture meter to assist in the tuning process. The original injectors do the job just fine, duty cycle is never more than about 72% so bigger injectors are not necessary. This system has been completely trouble-free for about 3 years, from the moment I first started it - I could not be happier with it. It does not offer dual advance curves and such, like the Haltech systems, but one advantage is it has it's own hand-held programmer, and I did not have a laptop at the time, which you need to program the haltech, motec and others. From memory I think the system cost about $1300, plus the shock phone call from customs telling me I had to pay $300 import duty.
If you are on LPG that will also have to be tuned for the bigger motor.
All up, my 4.4 conversion cost me more than what I had been quoted for a complete 4.6 conversion including all the necessary electrics. I guess if you have a good motor sitting there, that is a good deal of the money already spent, but be prepared for the costs of getting the EFI system to run the bigger motor. The 4.4 has heaps of grunt, but probably does not go as hard as a 4.6. Fuel consumption (the term 'fuel economy' seems out of place when talking about Range Rovers) is pretty much the same as the 3.5; I run mostly on LPG and get 320km from 76L. When i had the LPG fitted to the car with the 3.5, it always ran more smoothly on gas. Now with the new EFI system it is a treat to run on petrol- smooth as a babies bum.
I did warn you thast this would be a long post, and I haven't even talked about how the engine reconditioner stuffed up the piston-to-bore clearances and had to start over with a replacement block when the first motor exhibited pronounced piston slap.
Anyway, hope some of this is useful to you.
regards

Ha, that was me on the old forum- long-winded coot! Still have that car- as I posted on here a while back I will probably wreck it soon as the car is worn out, but the motor still runs a treat, has done about 125,000km since the swap (stopped being my daily driver when i bought the 94 soft-dash) and never a problem since installing the SDS EFI system. If you want a 4.4 that is already sorted you could make me an offer!