The V8 Owners Forum -

I'm looking at buying a newish Rangie mainly for towing my track and autotest cars around and for going to work when the TVR is playing Billy Sugars.

Not going to do that many miles unless I really like it or one of the sportscars needs major work.

I know nothing of LPG other than the basic sort with a single vaporiser in the inlet. What's the deal if I want LPG on the later Bosch/Sagem variant of the Rv8? I assume an additional fuel ECU and a second row of fuel rails and injectors as a minimum.

My preference would be the 2nd set of injectors all controlled with the original management, and switch fuel and timing maps for LPG so that I can extract decent performance from the LPG mode. I may even be convinced to increase the compression when I change the camshaft since LPG has a RON of 114 More torque is always good.

I know VEMS can do 2 maps now, but I don't want yet another "project" vehicle - I want to retain as much OEM stuff as possible, I wouldn't object to making a switchable dual EEPROM board to go in the OEM ECU and have a relay to activate the appropriate injectors...

So is such a system available off-the-shelf? And is DIY fitting + inspection for insurance an option? (I am reasonably competent)

Thanks.

Probably worth talking to Mark Adams as he's 'da man' on those ECU's to find out what can be done.

I think he would have to be involved anyway for a re-chip even if you did use a second parallel ECU for the gas to make sure the main ECU doesn't go into limp mode or flag loads of faults.

Chris.

At that age, it's a Bosch setup (Thor engine), possibly one of the more awkward engine ecu's to make work properly with LPG. Having said that, I've done quite a few now, with no issues.
Use an OMVL Dream 21-N gas system with the vapouriser pressure set to 1.2 bar for a 4.0 engine, and 1.8 bar for a 4.6. Be very carefull to ensure that the correct injector-cut harness corresponds to the correct gas injector or the engine ecu will chuck a major teddy.
There's no need to play with dual timing (standard ecu will actively advance the timing slightly over time anyway, using the knock sensors to "find" it's self-learning limit), leave the vehicle electronics well alone or regret it later - there are so many functions whereby the engine ecu has to talk to the body computer and gearbox ecu (assuming it's an auto) that you'll end up creating a new problem every time you resolve another!

The Dream 21-N is a piggy-back type, fully-sequential gas system - it intercepts the signal that the vehicle ecu is sending to the petrol injectors and turns it into a signal that the gas injectors will work with, the clever bit is the calibration of the gas ecu to ensure that the petrol fuel trims do not wander over time, get that bit right and it's a very, very good system. Not for the faint-hearted though so if you're not familiar with SGI systems I wouldn't contemplate trying a diy install!

Thanks Badger. Looking like a possible in the new year just before the new competition season starts for me and I start doing lots of towing.

My day job apparently more challenging than being a rocket scientist...
And I've stripped and rebuilt a TVR Griffith (fixing most of what TVR got "wrong" along the way and installing and tuning a proper ECU and wiring in place of the Lucas 14CUX) I hope this shows that I'm not faint of heart!

I'm wondering how good the Bosch ECU is at advancing the timing - most of the OEM ECUs I've seen will only advance until they get to the minimum best timing limits set in the tables (as worked out by the manufacturer). These will obviously be for petrol which IIRC burns faster than LPG, so without 2 timing tables, then there will always be a compromise. I hope that this won't be too much of a compromise and that switching between the 2 fuels won't upset the timing curves as it does when going from Super to normal unleaded (only in an emergency!) does in my Subaru... Hence my desire to have separate tables if possible.