Thread: Pics of LPG setups on EFI V8's wanted.

Thanks again Ron -

If you can measure the plenum (or the dougnut you have from the 4.6) that would be great.

As you would have read from the start of this thread the engine is going into a SIIB and there is not enough room for the system in the first image to fit under the seatbox (where the engine is). The system also had a history of back firing, which may be the flame trap, or the position of the PCV into the plenum after the LPG was introduced. Whatever the reason, either way I am not content to use that LPG system in the project vehicle.

My hope is to use a dougnut similar to that on my 4.6 Motec/EFI RRc, but using the standard Disco 1 ECU and MAS has me a little out of my knowledge base.

Diana

Hi Guys, All EFI engines to 1998 use a 72mm diameter at the manifold. You can only use a mixer ring at the manifold when you have a MAS without moving vanes. Ergo, to use an early 3.5 litre mechanical vane sensor you need a plate mixer before the MAS and a backfire protector valve after it. If you are using the later type (3.9, 4.6) MAS you should be using a mixer ring of around 45mm bore size. Otherwise strangulation results! 80% of backfires are due to poor ignition timing, plugs and leads. 10% are because of poor petrol start relay adjustment/wiring. The other 10% are mechanical failure.
Lean mixtures and high throttle openings cause high ignition voltages to induce sparks at other cylinders. Proper electricals can reduce backfires to very occasionally only.