Is anyone on here running spark control with LPG (propane)?
I've got EDIS8 installed on my Range Rover (3.5 RV8) and with Megasquirt controlling the spark timing (hasn't been wired up for fuel yet). It's running nicely on petrol using a known good spark table from a similar engine, but the LPG map definitely needs some work. So far we've just tried moving the whole map a few degrees but can't get decent performance across the rev range, so I'm guessing LPG needs a steeper curve.
If anyone has either an LPG spark map for a similar engine or petrol/LPG maps for comparison - or even better can point me at some decent information on ignition timing for LPG - I would be very grateful
G'day Geoff
I had my car (351W) running on LPG using "extra" code, although not the same as yours I was running 18 deg inital to 32deg total, all in by 2800. After 10 years of trying to get performance out of LPG I finally gave up a few months ago. Ive heard lots of people saying they can get good performance but I never actually saw it (words are cheap)!
Cheers - that's something to go on (that actually the most information I've got anywhere, so far...).
Do you know what the equivalent advances were on petrol for your engine?
In theory you should be able to get perfectly good performance from LPG, but ideally you need to do a bit more than change the ignition timing - I'm told a higher compression ratio helps a lot. My truck is not sports car anyway, and in the UK it's a very simple choice between fuel I can afford to buy and fuel I can't... It runs well on LPG but there is a noticeable difference in performance.
I've got a broken 3.9 RV8 (the trucks original engine) in the garage which I'm hoping to find the time and money to rebuild as something a little more interesting - if I do that it'll be tweaked to run best on LPG, but it'll still be compromised by the need to run on petrol too.
No problem Geoff. I had been running on LPG for the past 10years, it was a dual GRA (Gas Research Australia) system, supposingly one of the best available (at the time at least). I don't do a lot of miles so the price of fuel isn't a huge worry. It's funny, when I had a standard 302W, the gas system seemed to perform very well (for what the engine was), now with the modified 351W it just seemed to be missing something (my mates keep saying gas is for barbies and petrol is for cars), I still had just under 400HP but was expecting mid 400's so I only just pulled it off a little while ago. This is the first time I have used petrol in 10yrs! I've heard a lot of "stories" about upping the compression; although gas has a hi octane rating the ROH is not that good and according to our local Shell techo's. It is also effected by heat, ie loses it's octane rating at a rate of knots (gets up to 45C where I live), their recommendation was to stay under 10.5:1 (which I did). Also note in Aust. we do not have laws covering the propane/butane mix, sometimes we can get 60/40 other times 99/1 which is also a big problem. I beleive in the UK you have 99% propane (which is the one you want for performance). I'm still trying to sort my EFI system out so I still don't know the best curve for my engine but I can tell you the gas system I had was very reliable and hassle free (often suspected but never proven). For a standard engine I think gas is great, and the prices you poor guys pay for fuel in the UK can only bring tears to my eyes... One last bit of advice (past on to me) is not to run too much vacuum advance, up to 6 deg max. All the info I have given is either "what worked for me" or heard from word of mouth, I don't confess to be a gueru but having said that, I could tune the car for better driveability than any dyno tune shop I took it too!
Very nice - much shinier than mine (well, it's a working land rover - I'd only get it mucky again... ). 400bhp...I should think my current 3.5 is good for about 150bhp on LPG.
Only 6deg vacuum advance is interesting. I'd assumed (based on very little data) that LPG would need a steeper curve than petrol - this suggests the opposite.
Given that I've been able to glean very little data on what the ignition map for LPG should look like I think, like you, I'm going to end up doing it by methodical trial and error. Doing it by 'that feels better'...'nope, worse, put it back' is rather subjective and imprecise but I guess in some ways it's the best way to tune for drivability rather than outright performance (which is what I need - this is my everday car and offroader).
My map starts at 10 deg and up to 20 deg total all in by 3500rpm. Probably too high in the rpm though. This is at 100kpa. Under boost it runs 12 deg total. None of this is dyno tested. It goes hard so I am not really bothered.
It is soo very much horses for courses though. My last engine in the car, a 1985 2.3 liter BMW 6, made best power on the dyno on LPG at 26 deg total. This was before it was turbocharged. It made approx 100KW at the engine at 5500rpm. turbo on 9psi it made 180KW at 5500 with total timing under boost backed down to about 16 which was still a little high.
Small bore and good chamber means less advance needed. What your particular engine likes is really a dyno tune project.
Take a look at a stock curve for your motor. Give it more initial and less total. Probably in the order of 6 degrees or so.
My map starts at 10 deg and up to 20 deg total all in by 3500rpm. Probably too high in the rpm though. This is at 100kpa. Under boost it runs 12 deg total. None of this is dyno tested. It goes hard so I am not really bothered.
It is soo very much horses for courses though. My last engine in the car, a 1985 2.3 liter BMW 6, made best power on the dyno on LPG at 26 deg total. This was before it was turbocharged. It made approx 100KW at the engine at 5500rpm. turbo on 9psi it made 180KW at 5500 with total timing under boost backed down to about 16 which was still a little high.
Small bore and good chamber means less advance needed. What your particular engine likes is really a dyno tune project.
Take a look at a stock curve for your motor. Give it more initial and less total. Probably in the order of 6 degrees or so.
Pete
I know this was years ago,
But i'm looking for LPG maps for an M52TU, i just need an reference.
You said that it runs good on 26 degree...i found that every engines are pretty much the same on LPG the max torque its found on 25 to 27 degree and i already seen some running steady 26 since 2000 rpm all way up to redline...
So what is your advice? Do you have some of that maps you used on the 6 cilinder before you boost it?
). 400bhp...I should think my current 3.5 is good for about 150bhp on LPG.