Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[The Doctor]

Octane rating of LPG is nice and high, 108 or silmilar, which allows for far more agressive ingition timing without risk of detonation. Now the LPG lets us down by having a slower flame front and lower calorific value etc, so can we make some of that lost power back with a good engine chip? This one is a very good price IMO and if it does what it says, will help optimise the engine for LPG too.

Your thoughts please o wise ones.

http://cgi.ebay.co.uk/OPEL-VAUXHALL-V6-X30XE-chip-232HP-305NM-Omega-B-MV6_W0QQitemZ140195362341QQihZ004QQcategoryZ32094QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

[Kevin Wood]

A bit more ignition advance isn't a bad thing for LPG but you have to maintain the ability to run safely on petrol.

My guess is that it's not significant enough an improvement, otherwise, LPG kits would take over control of the ignition in the same way that they do for the injection.

If I were going to change anything I'd go to someone who can map the system and experiment, rather than buy an unknown and unsupported chip off ebay.

Kevin

[Paul M]

My guess is that it's not significant enough an improvement, otherwise, LPG kits would take over control of the ignition in the same way that they do for the injection.

The problem with that is that it's easy to clone the petrol ECU's injector behaviour, and just modify the pulse widths to suit, you're not advancing the injection timing any. Advancing the timing based on the ECU's timings isn't so easy -- it would need non-causal signal processing which is obviously impossible, so it would take some other kind of trickery to get the signals out of the ECU earlier. Of course you could bypass the ECU altogether and do your own timing, but LPG ECUs are a lot more basic than the car's ECU, so without developing a system that can tap into all the sensors (MAF, MAP, knock, temp, etc) it would be a backwards step.

Old style distributor ignition is obviously a lot easier to advance, and this is exactly what many people do when running on LPG. You just have to remember to drive gently on petrol

[Kevin Wood]

The problem with that is that it's easy to clone the petrol ECU's injector behaviour, and just modify the pulse widths to suit, you're not advancing the injection timing any. Advancing the timing based on the ECU's timings isn't so easy -- it would need non-causal signal processing which is obviously impossible, so it would take some other kind of trickery to get the signals out of the ECU earlier....

It's not that hard, tbh. you follow the ignition events from the main ECU and run a time-based "virtual flywheel" to mark time between them. Then you can shift the timing wherever you want, because your estimate of the crank position is being updated by each ignition event from the main ECU. It's not non-causal because you know the sequence of the ignition events and the angles between them.

So, your ignition event for cylinder 1 may have to occur before the  ignition event from the main ECU, but you can express that as a number of degrees after the ignition event from the main ECU for the previous cylinder (number 6).

This is in effect what the main ECU is doing between pulses from the crank / cam sensors. It knows where on the wheel the pulses come in and assumes a constant angular velocity between them, so can generate events at any angle of crank / cam rotation.

Kevin

[Ross]

If you have an Auto 2.5 or lower the chip will blow your gear box but this doesn't apply to manual cars. If you have a 3.0 or higher Auto you will be fine because they can handle the extra power.

[Kevin Wood]

I'd be surprised if a chip would cause a problem on a 2.5 petrol, TBH.

With the 2.5 Turbo Diesel engine this is an issue, but that's because the standard chip was designed to cripple the torque output of the engine to within the spec of the AR25 gearbox.

On a petrol engine, peak torque available is largely related to capacity. Chipping will only improve the performance at the extremes where torque isn't at a maximum anyway, and even than, only by a relatively small margin.

If considered in conjunction with LPG running, it will probably only restore some of the performance that was lost converting to LPG anyway.

Kevin

[markey mark]

If you have an Auto 2.5 or lower the chip will blow your gear box but this doesn't apply to manual cars. If you have a 3.0 or higher Auto you will be fine because they can handle the extra power.

 not on petrol bud only oil burners !!

[TheBoy]

If you have an Auto 2.5 or lower the chip will blow your gear box but this doesn't apply to manual cars. If you have a 3.0 or higher Auto you will be fine because they can handle the extra power.

its only diesels that melt the boxes due to the massive torque. petrols are normally ok with std box