Yup, been running LPG for a lot of miles now. Now had to re-shim the head twice and the engine will soon be coming out for a new clutch so will strip and have a good look at things then. Probably worth going for valve lube too as it looks like the cost per mile is minimal and will save the head wear.
Mine is the Prinz VSI system which piggybacks from the standard injectors to fire the LPG injectors, so all the mapping, safeties and closed loop control of the standard ECU is retained. The LPG injector time is proportional to the time the standard ECU sends drive to the petrol injectors with a 'zero and span' adjustment so it's not the most accurate on fuelling. I think newer system can add a MAP sensor to allow more precise mapping.
Mine doesn't affect ignition timing, and I'm not aware any others do. There are gains to be had by running a bit more advance as LPG is much higher RON and I believe slightly slower burning than petrol.
My setup uses a donut type tank in the spare wheel well, which doesn't leave much boot space when you still want to carry a spare wheel. A small price to pay to be able to run a GT4 for the same fuel cost per mile as a small diesel. The only thing I will point out is that short journeys are not efficient as it needs to run on petrol for a mile or 2 until the engine is warm enough. I still have a small diesel for trips less than 20 miles.
There was someone on the OC who paid near £2K I believe for a full professional install which apparently gave full power on LPG. I did ask for more details on manufacturer details but didn't get any information. He's since sold the car I believe.
One of my friends fitted a secondhand EBAy sysem which cost £200 on his GT4 with similar results to mine. I dodn't know the details of it but I believe it was fitted to a Lancia turbo beforehand.
A few old threads. (I think the ccuk ones are visible without joining but it's not a huge sum and a nice club anyway)
viewtopic.php?f=1&t=6523&hilit=regressionhttp://www.celica-club.co.uk/forum/inde ... ion-going/http://www.celica-club.co.uk/forum/inde ... xperience/
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