[greg123]

Hi All, I'm a new member looking for my first 9000 turbo. An ex pro freelance mechanic, LPG (gas) qualified and have had many cars but not a 9000 turbo. Looking at a 2.3 LPT auto. I will be converting it to LPG which means it will effectively be running on racing fuel, about 105 octane. Normally that means it's pretty impossible to get detonation or pinking, usually to get the best from the engine about 12 to 15 to 1 compression would be required and another 5 to 10 degrees static advance. This got me thinking. When on gas, due to the nature of the fuel detonation isn't likely to be a problem. So the normal reasons for keeping the apc don't apply. What would happen if I disconnected the boost sensor on the car so that it always gave an ambiant pressure reading. Keep the knock sensor and ecu standard, then adjust the wastegate to give around 1 bar boost. According to my theory the ecu wouldn't know that the turbo was boosting over standard and so wouldn't interfear with it. If pinking occured due to ignition timing too advanced it would automatically retard it still due to the knock sensor and because the ecu would think there was no boost it would be setting the ignition timing very advanced (it retards it as boost increases to stop pinking) which is what I would need to make the LPG run right. Anyone spot any holes in this plan? Let me know please! Greg. [email protected]

 

[kprm77]

Welcome to SaabScene Greg(UK)

Not sure on the answer to this but Gassy is your man.

He has a 9000 2.3T Auto with LPG which has been modded up to 250BHP+. Think it's done over 200,000 miles!

 

[DrSaab]

Hi & welcome to saab scene from a newbie myself.

Be careful is my advice

I had a full blown 2.3T converted by Howe Engineering in herts. who are pretty experienced with saabs and started with LPG a few years ago.

They had quite a few problems with turbos running the older type of LPG conversion but it might be worth giving them or AMS autogas (advertised on this site) a call to discuss problems in more detail.

As far as derestricting APC - lets just say I had some manifold pre-detonation and managed to get through 3 intercoolers............but

Whayhay!!

I sure you know what you are doing but it might save you a few pennies and stressful moments to have a chat to these chaps. Incidentally, Howe had enough trouble with the SAAB conversions that they have stopped converting saab turbos

Good luck & welcome again

 

[gassy]

I've run my MY'91 2.3t on LPG for about 50k miles. It now has 262,000 on the clock and goes like the clappers - 10% more bhp than when running on petrol. It's a Lanzi Renzo (?) system and also was converted by Howe Engineering, who found it difficult to set up initally, but once set its been pretty stable. Regarding your tech questions, I suggest that you call Stuart at Howe's on 01763 289521, or perhaps see if Leon from Saabscene who also runs on gas and knows Howe's quite well, might have some suggestions.

And welsome to the board, BTW

 

[mark e]

Originally posted by Greg (UK):
[qb] What would happen if I disconnected the boost sensor on the car so that it always gave an ambiant pressure reading.   [/qb][/b]

Well, I don't claim to know anything about LPG conversion ECUs work with Trionic, but in terms of Trionic management, I reckon disconnecting the MAP (boost) sensor will send your fuelling up the swannee!

Trionic relies on information from the MAP (boost) sensor to help control fuelling and ignition- regarless of what you might be doing with boost presures. If, as you say, detonation is not going to be a problem on LPG, then you could run an MBC valve (about £40) and set the boost level to just below fuel cut out.

I think you need a chat with someone who knows LPG and Trionic...

[edit]
Oops I forgot- Welcome, Greg!

 

[greg123]

I think the point about the map sensor being disconnected stuffing up the fueling isn't valid as it would no longer be fueled by petrol! But I could leave it in sure, however what would happen when I turn the boost up after that? Actually if it only cuts the fuel not the ignition then I'd still be okay. Does anyone here know if the ignition system is adaptive, ie if it doesnt' detect detonation will it gradually advance till it does and thus 're-map' the ecu depending on the fuel it's running on? OR is it a cruder 'here is your map, if you detect detonation start retarding timing, if that fails start cutting boost' which won't allow the ecu to automatically advance up the timing with better fuel? I have to admit I can't see a way round the backfire problem at the moment, backfire valves won't work as they would let the turbo pressure out as well! I could go for a gas injection system but it's a lot of money!!!