Thread: Thor / Motronic EFI onto 3.5 V8

I have written several posts on this.
I did it with a 3.9 14CUX about 6 years ago.
1 The Thor rail has no fuel return so needs a pump in tank with pressure regulator in tank. The pump in tank is higher pressure than normal as are the injectors.It is easier and cheaper IMHO to fit an external pump and use an early 3.9 fuel rail with the regulator on the RH side, which will fit under the Thor. The injectors can be Bosch yellow available on ebay from the US for around $100 a set. You can then use a RRC tank, or use your tank with a fabbed return line. You need a surge tank if you do this.

2 The Thor has to be modified at the front as detailed in your link, by machining a hole and ledge for the Thermostat. you can use a 3.5 or 3.9 housing.

3You have to fab accelerator linkage.

4 You do not have a vacuum advance tap so will need to have a computer generated vacuum advance curve.

5 I used the 14CUX stepper but your injection ECU could maybe use the later one, but you would have to check this with the ECU maker.

6 You could use a 14CUX loom to be easy if the ECU is batch fire. I personally would not attempt sequential as IMHO the results are not worth it, as sequential is mainly for emissions and at low revs only.

On my 3.9 the Thor gives about 20-30% more torque between say 1500 tapering to maybe 5% at 3000rpm, for a loss of 10% at high revs over 3500.
If you are looking for more power at high revs you will not get any but the car will be more drivable.
Any questions please ask.


Regards Philip A

Thanks Philip.

The Spitronics requires:
- a coolant sensor : standard Thor unit is NTC 2K so should work
- an air temp sensor : I need to see if the Thor air temp sensor that is part of the AFM unit (??) will still work for this (NTC 10K?)
- an after-market Manifold Air pressure sensor plumbed into the manifold with the sensor body as close to the manifold as possible

I can plumb in a Bosch external HP pump after the standard external LP pump, and an adjustable pressure regulator between pump and fuel rail. I just have to see if this will work?

tank -> ext LP pump -> ext HP pump -> regulator -> fuel rail

Pipes between HP pump and the rail will have to be upgraded to 8mm HP DIN hose or else copper pipe.

I'm looking at a "split-sequential" injection : matched piston pairs get a fuel injection spurt together based on the piston movement order (1-8-4-3-6-5-7-2 = 1&6, 8&2, 4&7, 3&5 or something similar). This seems to be an excellent compromise between full sequential and 4-cylinder batch.

The Spitronics ECU can use auto-calibrate to match to the Thor TPS: it's basically a set-once feature.

I'll use a pair of 4-wire lambdas for the AFR monitoring in closed loop. Our petrol RON is variable in practice, and we also have altitudes from seal level to over 2000m ASL.

Yes the Spitronics SEEMS capable of using the Thor stepper valve, again this will require some testing.

I have read the thermostat issue: can I not just plumb that coolant line to the bottom hose on the factory cooling system?

One of the issues I have is crank timing: I'd like to run a multi-coil wasted spark system, but picking up accurate timing off an old dizzy is problematic so I need a crank wheel or else a Hall effect sensor off the flywheel. I doubt the old 3.5's had any flywheel timing?

Expected returns from this are:

- better low rev response (current SUs are "blubbery" despite being checked and balanced)
- better AFR across the range (SU not known for good AFR at all revs)
- low rev torque increase a bonus
- small kW increase also a bonus
- better cruising consumption (current 5km/L or worse)
- good response to altitude changes

Unfortunately the Spitronics doesn't have a knock sensor input channel.

I have read the thermostat issue: can I not just plumb that coolant line to the bottom hose on the factory cooling system?

One of the issues I have is crank timing: I'd like to run a multi-coil wasted spark system, but picking up accurate timing off an old dizzy is problematic so I need a crank wheel or else a Hall effect sensor off the flywheel. I doubt the old 3.5's had any flywheel timing?

re the thermostat. I don't really understand what you hope to do, but I went conservative just duplicating the original system.
The Thor has a plain pipe to the radiator with the thermostat in the bottom hose and a lot of complex plumbing.

The only reason that they have these new system is quicker warm up for reduced emissions and the new sytems can cause problems with head gaskets eg FL1. If you have the front machined you can use the original thermostat and hoses which make it much easier to fix if you break down in the bush.

See here for crank timing gear


Trigger-Wheels

Again I kept with my dizzy for cheapness and simplicity. I recently fitted a brand new Lucas distributor that I picked up cheaply, but there seems little performance difference. My vacuum advance is controlled by a Unichip (Good ZA product). You have to keep some of the dizzy to run the oil pump.
Regards Philip A

Regards Philip A

Do a search for "Trigger Wheels" they sell the toothed wheels to fit on the back of a Rover V8 harmonic balancer + they sell VR sensors and mounts to match. Also have a look a some of the Megasquirt sites as there is lots of info which could be usefull for your conversion, try LR4X4 there is lots there on Rover V8s
Cheers
Nick

Originally Posted by jakeslouw

Expected returns from this are:

- better low rev response (current SUs are "blubbery" despite being checked and balanced)
- better AFR across the range (SU not known for good AFR at all revs)
- low rev torque increase a bonus
- small kW increase also a bonus
- better cruising consumption (current 5km/L or worse)
- good response to altitude changes

Have you considered a supercharger with suck-through single SU?

Having just read Allan Allard's superb book "Turbocharging & Supercharging" it seems to me that a blower meets all of your objectives with much less hassle to fit. In addition the kW increase will be significantly more. The Land Rover engine is ideally suited being low-compression,

Cheers Charlie

an air temp sensor : I need to see if the Thor air temp sensor that is part of the AFM unit (??) will still work for this (NTC 10K?)

MAFs do not have air temperature sensors. these are only needed by flappers ( or MAP sensors) to correct air flow to air mass by compensating for temperature. A MAF does it automatically.

So you will have to source one. They are usually fitted at the air inlet.

BTW a MAF equipped car is much more tolerant of altitude and tuning differences than a MAP car. If your ECU can accommodate a MAF then that is the way to go.
Regards Philip A