Hotwire EFI installation

[Philippe Holland]

Hello to everyone,
I have read a number of excellent threads about installing a Hotwire setup on our cars, but I still have a number of questions and hope some of the experienced members can point me in the right direction.
The objective is to make the simplest installation possible almost making it look as if it was a factory option. I would go as far a painting the plenum chamber and associated parts in Rover-rocker-cover-grey and use a modified Rover/Land Rover air filter box.
My car is running well on its points ignition and I would like to leave it like that for the moment. However tempting Mega Jolt and Mega Squirt systems are, I am looking for a real old school (and cheap) approach. The car will still retain its 4 speed box (I love the clickity-click 303 rifle mechanism feeling)
My car is a V8 S (possibly the oldest surviving LHD) with a 10.5:1 comp and standard heads.
My plan is to die grind the relief for the injectors with the heads in situ and tweak the valley gasket as required.
I would fit a swirl pot in the boot.
My questions are as follows please:
- Can I use the existing fuel lines and does this complicate fitting unions or fittings? I believe the lines are nylon.
- If I use the reserve fuel line to feed the high pressure pump because it is lower, (then filter) can I use the regular fuel line as the return to the swirl pot and then, should the return go from the swirl pot to the original main fuel outlet or to a higher place in the tank? Where in this case is the best place for the return to connect to the tank please?
- Should I fit a separate fuse box for the pumps/ecu/inertia switch for peace of mind?
- Can anyone recommend which inertia switch I should use?
- Do I really need a road speed transducer?
- Can I modify the P6 rocker covers to work with the Hotwire PCV requirements?
- Companies like RPI sell a throttle cable kit with their Edelbrock/Weber carb kits. Can this be modified for an EFI setup or is there a simple solution?
I have a complete 3.9 Hotwire system and also a 3.5 flapper plenum chamber. Can I use the 3.5 plenum with the rest of the 3.9 system? I prefer not to have 3.9 showing...

And my motivation for doing this conversion? I found a lovely 'fuel injection' script logo that would look great on the boot!
Many thanks for your input.

 

[1396midget]

Hello to everyone

Hello!
I've not done this, but have converted the MG to fuel injection and have a lot of bits to do the same to the P6 when life gives me time.

- Can I use the existing fuel lines and does this complicate fitting unions or fittings? I believe the lines are nylon.

I'm not going to. I won't be trusting low pressure 70s pipe with high pressures

- If I use the reserve fuel line to feed the high pressure pump because it is lower, (then filter) can I use the regular fuel line as the return to the swirl pot and then, should the return go from the swirl pot to the original main fuel outlet or to a higher place in the tank? Where in this case is the best place for the return to connect to the tank please?

intercept the original return to the tank with the swirl pot. So from the tank it goes: Tank, filter, LP pump, swirl pot input 1, swirl pot out (Bottom), HP pump, injectors, retun line into swirl pot input 2, exit from swirl pot (top) back to tank.

- Should I fit a separate fuse box for the pumps/ecu/inertia switch for peace of mind?

yes, plus relays for the HP pump

- Can anyone recommend which inertia switch I should use?

I used one from a Rover 200, same as mini - http://www.minispares.com/product/C...ch/classic/inertia switch.aspx|Back to search

- Do I really need a road speed transducer?

from my research, no.

- Can I modify the P6 rocker covers to work with the Hotwire PCV requirements?

not sure, what does it need? I'd be tempted to run breathers as per engine, so route as with carbs but take it to in front of the throttle body, keeping the rockers the same.

- Companies like RPI sell a throttle cable kit with their Edelbrock/Weber carb kits. Can this be modified for an EFI setup or is there a simple solution?

I've not thought about this bit yet...

I have a complete 3.9 Hotwire system and also a 3.5 flapper plenum chamber. Can I use the 3.5 plenum with the rest of the 3.9 system? I prefer not to have 3.9 showing...\

no, the flapper systems are totally diffferent with integral throttle body and different idle arrangements. The base is different too I think.

And my motivation for doing this conversion? I found a lovely 'fuel injection' script logo that would look great on the boot!

[/quote]

excellent.

Just my 2 cents (as it were) so happy to be corrected/educated!

 

[Quagmire]

The rover v8 breather setup is pretty straightforward, the hotwire had a filter on the passenger rocker at the rear. The drivers side has a canister full of wire wool at the front which is then piped across into the plenum by the throttle butterfly.

You can use a flapper plenum with a hotwire manifold, I have this setup on my landrover. However be aware that flapper manifolds are different in how they clamp the injectors (old style). Plenum-wise the throttle body is always integral to the plenum, from flapper right through to GEMs, which is what I have on my 3500s. The differences in various eras of plenums are mainly the idle air arrangements. Flapper had a bimetallic 2 wire valve, hotwire had a 4 wire stepper at the rear of the plenum, and gems has a 4 wire stepper motor on the front by the throttle position sensor.

Most air/vacuum connections for brakes etc are from the ram housing, which the plenum bolts to.

Throttle wise I made a "seesaw" to convert from the throttle linkage to cable. Used an uber short cable from a LHD Discovery to connect the seesaw to plenum.

My car is here:

viewtopic.php?f=21&t=16625&start=225

It has "4.6" on he plenum, which is a lie!

Although I havent much chance to drive it much since I injected it as the rear suspension started clunking shortly afterward. Just got it back on the road yesterday with new bushes and had to get the train to work today due to a client bash!

 

[PeterZRH]

If you're going to this much trouble then ditch the heads for later ones, they look identical but flow much better - mine cost all of £50. You can even skim them by 20 thou and use the better composite gasket while keeping the 10.5:1 10-12bhp in pure efficiency gains on top of the 30+(?) for the EFi. No need for any grinding either.

While you're at it renew the timing gear/chain and tappets and consider a high volume oil pump. These things cost very little while you have everything apart it makes sense.

 

[1396midget]

You can use a flapper plenum with a hotwire manifold, I have this setup on my landrover.

Ooh cool I didn't know that. Every day's a school day!

Plenum-wise the throttle body is always integral to the plenum, from flapper right through to GEMs, which is what I have on my 3500s.

Doh! Of course it is. Silly me...

 

[Quagmire]

You can use a flapper plenum with a hotwire manifold, I have this setup on my landrover.

Should have said that if you do go this route with the Hotwire ECU you will need to figure out idle air control and will need to blank off the hole for the 9th "cold start" injector. I forgot to mention this as I am using MS, so the idle thing has not been an issue I have had to overcome - I used a totally different (Bosch 3 wire PWM valve from a SAAB) altogether.

Hotwire used the 4 wire stepper idle control valve at the rear of the plenum I believe, so to retain this feature you would need to find a way to plumb a compatible type of valve into an available port on the ram housing instead, which is where Flapper feeds its idle air in.