Time Advance Processor for LPG(Propane)
Time Advance Processor for LPG(Propane)
(OP)
I would like to know if there is any advantage in using this devices on modern cars(with knock sensors). I found controversial answers to this simple question. LPG Kit installers told me there aren't any advantages but they can't say why. It is very hard to understand their language...they talk about things like "the engine get used to LPG" but they can't explain it in technical language. I know that LPG burns slower than gasoline so you need more spark advance at lower to medium revs but less spark advance at high revs(I don't know the reason for this, thought). However if you have active knock control the ECU will always ignite near detonation(is this right?). If so is this option(detonation near knocking) always the best(thermodinamicly it is but for engine and cat life span, I don't know). Can someone explain me better how knock sensor information is used by tge ECU.
Thank you very much...Happy new year
Thank you very much...Happy new year





RE: Time Advance Processor for LPG(Propane)
The disadvantage of taking to installers is that they are just that-installers. They usually know little or nothing about the product they are selling. this lack of technical knowledge results in the vague, techno-babble answers you are receiving. This works for most people who are not technical. Engineers however, drive them nuts. Keep up the good work.
Regards
Dave
RE: Time Advance Processor for LPG(Propane)
Also the knock system is usually limited to an advance/retard limit, just in case the knock system goes insane it would clip to a safe point, thus saving your pistons/cat converter/and engine overall.
RE: Time Advance Processor for LPG(Propane)
Without the knock sensor, a safety margin taking worst case scenario into account must be used, thereby costing power and economy via reduced thermodynamic efficiency
Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: Time Advance Processor for LPG(Propane)
Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: Time Advance Processor for LPG(Propane)
LPG engines can benefit from timing enhancements at low and part range throttle for all the reasons stated above. At full or heavy load, no additional advance is really needed, not especially sure, but dyno test have confirmed it.
Franz
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: Time Advance Processor for LPG(Propane)
Thank you again…Any additional information is still welcomed.
RE: Time Advance Processor for LPG(Propane)
Thank you again…Any additional information is still welcomed.
RE: Time Advance Processor for LPG(Propane)
Personally I like to include a timing processor or remap a conventional distributor for whichever fuel I am using, it does indeed help squeeze performance. I would guess up to about a 10% horsepower improvement with a properly timed engine, on LPG compared to an LPG engine without additional timing. Also, most modern sequential injection systems do indeed connect to the ignition primary and will modify the timing curve, although a seperate device is not installed.
Note that the key here is that the system is a complete package, not one of the older piece-by-piece systems.
Franz
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: Time Advance Processor for LPG(Propane)
A check of all the EFI truck and car models since 1985 to about 94 for 5L and 5.7L engines shows this sensor is used only on the light trucks.
Why; because it is a protection for the engine from low rpm heavy loading causing engine damage from PING type of ignition that is too advanced for the load and octane of the fuel being used.
A secondary result of using a knock sensor is that ignition timing can be sort of crowded upwards (advanced) allowing the engine to make more low rpm torque in an unloaded condition plus a bit extra compression ratio.
The knock sensor is a quartz element that produces a voltage output that is processed by the ECM and applied to the spark advance tables causing a retard to occurr. The retard range can be as high as 8 degrees.
Once the knock program has been entered, the return to regular timing may not occurr instantly.
Going futher, high rpm knock is another story brought on by other conditions. Excess temperature, fuel leaness, lack of lubrication in the cylinders, excess oil burning etc.
Many heavy cars use the knock sensor with the smaller engine for protection from over load at low rpm such as the 4.6L mod engine in Lincolns.
Also keep Ping, pre ignition and Detonation seperated because they can be caused by differing circumstance.
As to the difference in design/operation when using an alternate fuel, i'm sure there are preferred operating parmeter such as might be found in testing and programmed into the ECM program after the alternate fuel detector has found the situation.
Some Ford vechicles are already alternate fuel equipped and their owners don't know it unless they read their owners manuel.
RE: Time Advance Processor for LPG(Propane)
RE: Time Advance Processor for LPG(Propane)
Franz
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: Time Advance Processor for LPG(Propane)
Thank you again.
RE: Time Advance Processor for LPG(Propane)
Franz
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.