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Old 21st July 2006, 15:19   #1
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Default How To Improve Performance In LPG driven car

With many manufacturer coming out with LPG...and with demand rising for after market LPG fittings....there comes one question in my mind about the performance of vehicle with LPG...

Apart from making slight changes like advancing ignition timing to compensate low burning rate of lpg...reducing spark plug gap then normal.....what may be the other methods which can bring lpg driven car if not at par then close to petrol performance......

Enjoy.........
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Old 21st July 2006, 15:29   #2
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Acetone

Just kidding man...I think the usual basic mods should work - conical filters, free flows etc, since they depend on air flow and not on fuel.
Do correct me if I'm wrong though.

Tri-phase module should also work according to Viper.

Any idea about porting/polishing?
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Old 21st July 2006, 15:41   #3
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I think whatever modification we do aiming to improve performance will show increament in petrol as well as LPG.....so there always remains the difference...let it be conical filter...free flow...iridium plugs,msd coils to name a few.....

Its because of the fuel charecterisitc of both fuels....the chemical reaction that takes place when fuel ignites must be so different with LPG......I would like to add ACETONE but in vapour form as cant add physically in tank.....just kidding...

My thinking is to bring car at par with petrol performance without burning hole in pocket....

Enjoy.....
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Old 21st July 2006, 16:50   #4
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The whole point of moving to LPG is to reduce costs and yes there is a defn drop inperformance due the inherent problems with the way the fuel burns, however please remeber the easiest way to increase performance on a lpg vehicle is to run it on petrol, if you want to continue running it on gas you will need to increase the amount of gas being flowed into the system which in turn will again hurt your pocket.
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Old 21st July 2006, 17:00   #5
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Quote:
Originally Posted by finetuning
With many manufacturer coming out with LPG...and with demand rising for after market LPG fittings....there comes one question in my mind about the performance of vehicle with LPG...

Apart from making slight changes like advancing ignition timing to compensate low burning rate of lpg...reducing spark plug gap then normal.....what may be the other methods which can bring lpg driven car if not at par then close to petrol performance......

Enjoy.........
Interesting thread!
In my experience with OHC and Baleno, three things mentioned helped and theres no difference b/w driving on petrol / LPG. They are
a) advancing ignition timing,
b) reducing gap in spark plug and
c) K&N filter...

Think a free flow would assist too.. but for all practical purposes dont feel the need of the same.
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Old 21st July 2006, 17:15   #6
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Sorry On/Off Topic:

1) If one wants to save money on gas why buy a flashy car in the first place
2) If you want more milage then why crib about lesser power
3) If you want both and are working towards it hats off for being a scientist.
4) If you run a mpfi car on LPG and sell it later do you realise the other who buys the car and wants to run it on petrol might face the need to replace a burnt fuel pump, faulty injectors.

PS: Most mods for petrol engines do work on LPG cars too, but you have to increase fuel flow, so no savings.

Last edited by Psycho : 21st July 2006 at 17:16.
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Old 21st July 2006, 17:23   #7
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Hey Psycho could you please elaborate on point 4 - burnt fuel pump and faulty injectors please?

Was thinking about LPG, so trying to weigh all the facts.

Thanks
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Old 21st July 2006, 17:26   #8
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Quote:
Originally Posted by Psycho
Sorry On/Off Topic:

1) If one wants to save money on gas why buy a flashy car in the first place
2) If you want more milage then why crib about lesser power
3) If you want both and are working towards it hats off for being a scientist.
4) If you run a mpfi car on LPG and sell it later do you realise the other who buys the car and wants to run it on petrol might face the need to replace a burnt fuel pump, faulty injectors.

PS: Most mods for petrol engines do work on LPG cars too, but you have to increase fuel flow, so no savings.
Ans:-
1) If one wants to save money on gas why buy a flashy car in the first place- Ans: Whats the connection?

2) If you want more milage then why crib about lesser power. Ans:- Whos cribbing?

3) If you want both and are working towards it hats off for being a scientist. Ans:- OK.

4) If you run a mpfi car on LPG and sell it later do you realise the other who buys the car and wants to run it on petrol might face the need to replace a burnt fuel pump, faulty injectors. Ans:- Its obvious you need to brush up on the working of a modern LPG system. So Amen.
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Old 21st July 2006, 17:28   #9
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Quote:
Originally Posted by Boom Shiva
Hey Psycho could you please elaborate on point 4 - burnt fuel pump and faulty injectors please?

Was thinking about LPG, so trying to weigh all the facts.

Thanks
Boom Shiva,
Out of turn, but may i suggest that you drive any of my LPG cars b/w Matiz/ Esteem/ OHC/ Baleno for yourself to get a feel of ANY/ALL of above above points. I would be most glad to help you decide. Just pm me.
Cheers.
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Old 21st July 2006, 17:40   #10
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Quote:
Originally Posted by Samrat Banerjee
Ans:-
1) If one wants to save money on gas why buy a flashy car in the first place- Ans: Whats the connection?

2) If you want more milage then why crib about lesser power. Ans:- Whos cribbing?

3) If you want both and are working towards it hats off for being a scientist. Ans:- OK.

4) If you run a mpfi car on LPG and sell it later do you realise the other who buys the car and wants to run it on petrol might face the need to replace a burnt fuel pump, faulty injectors. Ans:- Its obvious you need to brush up on the working of a modern LPG system. So Amen.
Sorry it wanst personal towards anyone, but I do find it quite crazy when people mention power, milage, mods and money saved in the same breath.

As for point 1 & 2 I was replying to the topic title

The modern LPG system is the same across all the ones I know of and yes I have worked on them. Even the newer systems do not realise that the fuel Pumps of the MPFI cars are controlled by the ECU and tend to run continuosly unless someone clever remebers to provide a seperate switch to the pump (it is not as straightforward as it used to be on the carbed cars). As for the Injectors they are still on the harness and keep pulsing without the fuel going through them wearing them out for the lack of lubrication (how many do you know of who remove the injector plugs?).

The aftermarket systems are designed to fool the ECU to think everything is normal and that is the key reason why manufacturers are not willing to give warranty on the cars unless the LPG car is manufactured by them directly.

So do take this as a list of questions to think of before you opt for one and not as a list of questions to start an argument on. thank you.

Last edited by Psycho : 21st July 2006 at 17:47.
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Old 21st July 2006, 17:44   #11
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Psycho is there any way to avoid any of these problems? Also, how long/how many kms before these things start happening?

Last edited by Boom Shiva : 21st July 2006 at 17:50.
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Old 21st July 2006, 17:46   #12
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Quote:
Originally Posted by Boom Shiva
Psycho is there any way to avoid any of these problems? Can I get a switch installed for the pump and plugs?
Please make sure that they do not cut the wiring harness and leave it open while installing the switch for the fuel pump, however all that needs to be done for the injectors is to disconnect the adapters behind them when you are running on LPG.
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Old 21st July 2006, 19:06   #13
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Well just to clear the air, here is my 2 cents.
  • If you go down to the atomic level both LPG and petrol are basically long chain hydrocarbons. The only difference is a few atoms here and there.
  • In fact OEM take a lot of pains to vapourize and atomise petrol with multihole injectors and swirl/tumple flows, so by the time the petrol reaches the spark-plug its also in gaseous form like LPG.
  • LPG has a much higher octane rating, so you can bump up both compression and timing advance to recover lost power.
Now regarding installations
  • There are a lot of chaalu mechanics out there who take kits designed for carb engines (cheaper) and fit them into MPFI cars by cutting and splicing leading to probs Psycho mentioned.
  • Just like all cars are not equal.........all kits are not equal.
  • A good kit will have an injector emulator module and a timing advancer module that keep the pump an injector just fine.
  • As far as power, if you are worried, buy a car that has more than enough power and then LPG it. You will still be fine. If you start with a car thats underpowered then it leads to probs.
  • Ultimately, the throttle response will never be as sharp as a petrol car. ( at least I havent seen one)
  • Again like Psycho mentioned, if you are in a mood for some fast driving just flick back to petrol let 'er rip for the next 20 - 30 kms. Not gonna hurt your wallet by much.
  • Pretty much any mod for a petrol car should show the same gains in LPG cars.

Last edited by Mpower : 21st July 2006 at 22:07.
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Old 21st July 2006, 19:17   #14
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Could you please recommend the best kits, so I can ask for them specifically and not end up with the aforementioned "chaalu" kits?

Thanks
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Old 21st July 2006, 19:49   #15
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Quote:
Originally Posted by Boom Shiva
Could you please recommend the best kits, so I can ask for them specifically and not end up with the aforementioned "chaalu" kits?

Thanks
Boom Shiva,
Kits are specific to cars. So depending on your vehicle a good mechanic would reccommend a kit..
The key point here is a good mechanic. I have been using LPG for 3 years, and have over a period of time converted all cars I have bought, cause of the value. For CNG it should be likewise, but i cannot comment first person.
For a new car nevetheless its better to ride out the warranty, simply because of the issue of the manufacturers not honouring warranty if you retrofit kits.
I had gone through the same torture when i installed in my first car. So i appreciate your apprehensions.
Cheers.
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