An ignition upgrade to think about...

[TomLS]

I run a pretty standard 3.5l SU carbed V8 land Rover Defender.
This weekend, in preparation for getting my LPG kit fitted, I refitted the A&R power amp from RPI that I bought a few years ago. Now before, this made no difference, mainly because the old 35DM8 dizzy I had was totally shafted!
Skip forward 4 years of no use, I fitted a brand new 35DLM8 with a new bolt-on ign amplifier. Everything was better: idle, power, range, reliability, and on long runs, my typical fuel consumption is appx 3.1 miles / litre. (2.3 miles / litre in town).

I've just driven 75 miles back from my parents house to mine.
After fitting the A&R, I was immediately impressed when it repeatedly started within 1 revolution of the engine on the starter, wheras it previously took 3-5 turns. It also had a smoother idle and pick up, and the ability to idle without choke at 20*C (previously had to be 45-50*C).
On the journey it picked up much more smoothly from low revs (<1000rpm) and was smoother throughout the range.
On long runs, my typical fuel consumption was appx 3.1 miles / litre.
On the way there, I used £32 of petrol.
On the way back, I used £23 of petrol!
Fuel consumption 4.05 miles / litre.

I'm staggered - it just goes to show these aren't just for people with LPG.

(and before you lot start, I have no affiliations with them, I just want to share my good experiences!)

[ged]

(and before you lot start, I have no affiliations with them, I just want to share my good experiences!)[/quote]

Are you sure your not just in denial!

[ChrisJC]

Sounds too good to be true!
More data is needed. Maybe you had a good headwind / tailwind.
Chris.

[TomLS]

Too good to be true is just what I thought - it's a 25% increase in efficiency!

I drove up in the dry, and back in the wet (so should be more drag etc created by my knobbly tires!)
Journey times were roughly equal (2hrs 10 and 2hrs 20)
I doubt windage was a factor as the route I take is very twisty, with much slowing and speeding, and largely sheltered by trees.

I didn't change my driving style at all - I still floored it occasionally!

Really bizzare, but I'm not complaining! I just hope it's a continued increase and not a one off! - further testing will confirm or otherwise!

[Denis247]

Some of those Egyptians who jumped into the river were in de nile.

Are you sure your not just in denial! [/quote]

[TomLS]

Still not in denial, believe what you will - I'm just telling you the facts & trying to help!

[DaveEFI]

Still not in denial, believe what you will - I'm just telling you the facts & trying to help!

If a different ignition amp made such a difference RPI would have been shouting it from the rooftops...

[daxtojeiro]

Years ago I bought one of those and fitted it. The car initially ran like a dog until I realised that the input was triggering off of the leading edge of the input rather than the trailing edge, so it had thrown my ignition timing out by a fixed angle. Swung the dizzy to where the timing should be and it was just the same as it was before.

I would check your timing to see if it is the same as it was,
Phil

[ChrisJC]

Good point Phil.

Do those ignition amps have a bypass mode?, so you can do a proper A-B test?

Chris.

[TomLS]

They have a wire which goes to the 12v feed on the LPG vaporiser, so that it runs at standard (distributor defined) ignition timing when the wire is live.
When you switch back to petrol and the voltage drops back to 0v, the timing is retarded by a value determined by a potentiometer in the circuit board (around 8 deg?) to supposedly provide optimal running on both fuels.
However as I was already really happy with how it was running, I didn't want to pi** about with the dizzy, and my gas set-up isn't fixed yet. Therefore, I just connected the switching wire to the positive terminal of my coil, making it run the same timing as the standard amplifier.

I have left the standard ign amp under the bonnet, so I'll run through a tank on the new amp, then a tank on the old to see if the figures hold.

I agree that it is unprecidented, so further research is required - soon I will see what the city mileage is like on the new amp - hope its better than the 9mpg I normally get...

[SteveRK]

I have fitted an RPI ignition amplifier to my 1993 3.9 Range rover classic. No difference at all - why? because there was nothing wrong with the original distributor mounted ignition amplifier.

The ignition amplifier circuit is not that sophisticated, it just needs to send a low voltage trigger to the coil.