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Old 31st May 2012, 23:14   #1
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Petrol car to Diesel car conversion - Possible?

Mods: Did search for this, but couldn't find any thread. Sorry if one exists and please merge.

May be it will sound like a dumb question, pardon my ignorance. But with sky rocketing petrol prices, is it technically possible to convert a petrol car to diesel car, provided legally if it is allowed. This is with the assumption that the manufacturer has both petrol & diesel variants of same car.

For e.g.
Swift VXI/LXI to VDI/LDI
Hyundai i20 Petrol to Diesel
Ford Figo Petrol to Diesel

1) What are the pros & cons of doing it?
2) What are the costs involved.
3) Is it better choice to sell of petrol car & buy a new diesel instead of conversion?

So many questions running in my mind, and hence this thread !

-Ravi
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Old 31st May 2012, 23:32   #2
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Re: Petrol car to Diesel car conversion - Possible?

Everything is possible, but the first 2 options are better avoided, reason being it’ll cost a lot and in my opinion never be as it would have been if it came from the factory.

Option 3 is the best option considering all the pros and cons. The modifications along with RTO charges will in my opinion exceed the initial difference if the car was new, if the engine is bought from the manufacturer for the change.

Look at it this way, I have a Petrol Logan, would love to convert it to a Diesel one, but it’s simply not worth the time and money, its better if I sell and buy a Diesel.
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Old 31st May 2012, 23:37   #3
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Re: Petrol car to Diesel car conversion - Possible?

Somewhere in the forum there is a thread on the differences between petrol and diesel engines. Please search and go through that to see the differences and realize why such conversion is not possible.
Even if you are talking about swapping a petrol engine for a diesel engine also, there will be too many modifications required to the car. Finally, engine is the most expensive part and instead of swapping engines you are better off swapping the entire car
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Old 31st May 2012, 23:57   #4
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Re: Petrol car to Diesel car conversion - Possible?

once upon a time it used to be done on a lot of imported cars without parts and ambassadors and jeeps. though it still can be done, pretty much everything under the hood needs to be changed, and would cost a ton(parts alone), and even after that, reliablity would never match factory levels.
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Old 1st June 2012, 08:42   #5
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Re: Petrol car to Diesel car conversion - Possible?

In addition to the engine parts, parts like suspension (Diesel Suspension is strengthened for added weight), transmission, also need to be changed to cater to suit the new engine.

Last edited by pvgeorge : 1st June 2012 at 08:44.
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Old 1st June 2012, 08:57   #6
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Re: Petrol car to Diesel car conversion - Possible?

About 20 years back, we had our petrol Ambassador converted to diesel - the same diesel engine which was used in Matador vans. I'm not sure if any other parts were changed during the conversion. We had the car for around 2+ years after the conversion during which time it did not give us any reliability issues.

During those days petrol-diesel conversion for Ambassador was pretty common (atleast in Kerala) and IIRC it was also possible to get the RC book updated legally to show the conversion. I'm not sure if the RTOs are allowing it anymore, possibly not.
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Old 1st June 2012, 08:58   #7
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Re: Petrol car to Diesel car conversion - Possible?

@Ravi, unless you have a rare car and absolutely must change the engine, pls do not go for conversion. Eg: an old Jeep, may be with a hurricane engine - and where you do not want to let go of that vintage vehicle.

There are enough cars (new & used) in the market today. It is much much easier to go for a replacement than the hassle of conversion.
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Old 1st June 2012, 09:01   #8
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Re: Petrol car to Diesel car conversion - Possible?

For god's sake don't even think of replace-and-upgrade. here's why:
1. If you want reliability, you should get all genuine parts from manufacturer. (so that they are compatible and will fit in the designated spaces). Atleast you can do this comparison in a Maruti (by buying Swift parts manual)
2. Brakes have to be improvised for the new torque
3. Suspension (coil and sometimes dampers) has to be stiffer - Already discussed above
4. Clutch system might require an upgrade
5. Batteries have usually higher AH (for diesel versions)
6. New ECU to support diesel engine. It should also support existing airbags and ABS units.
7. RTO/Insurance - You need to register your changes to stay legal way

OT: I did an evaluation to upgrade non VVT SX4 to VVT version. I was overwhelmed by the difference in part numbers. Earlier I thought its just change in engine headers. You can look at my threads and most probably you too might realize that its an expensive process.
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Old 1st June 2012, 09:11   #9
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Re: Petrol car to Diesel car conversion - Possible?

Quote:
StarrySky :About 20 years back, we had our petrol Ambassador converted to diesel -
devsoftech OT: I did an evaluation to upgrade non VVT SX4 to VVT version. I was overwhelmed by the difference in part numbers.
The engines in those days were much simpler.

Today we have a lot of electronics. And apart from the components, you will also have to change the harness.
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Old 1st June 2012, 09:53   #10
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Re: Petrol car to Diesel car conversion - Possible?

The cars which traditionally got the heart transplant were the old gen ones like Ambassador, Mahindra Jeeps, Contessa. Many of these got fitted either with the Matador OM616 engines which could be procured locally or marine engines used in boats which would be bought from yards etc.

Have even seen rare specimens of M800 getting a oil burner with those beefed up suspensions like one walking on high heals but these are far and few.

The new gen cars as the ones mentioned are lot complicated and would not be worth the effort. Though a bit off the actual question, if your purpose is to convert this for lower running cost, you can fit a CNG / LPG kit into the same vehicle and would get a better economy than the average petrol car.
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Old 1st June 2012, 10:12   #11
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Re: Petrol car to Diesel car conversion - Possible?

Ravi, if your sole intention of doing the transformation is to save money because petrol prices are increasing then its definitely a bad idea.
As pointed out by the experienced t-bhpians its not just the engine which is changed when diesel variants are introduced.
Better follow the LPG/CNG route for maintaining economy.

Also even though diesel cars give more mileage and cost of diesel is less its not always profitable to buy and run a diesel car.
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Old 1st June 2012, 10:36   #12
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Re: Petrol car to Diesel car conversion - Possible?

With a lot of budget and expertise - Possilbe ? - Yes

Advisable - Hell no ! You would not stand to gain anything, but compromise a lot on reliability.
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Old 1st June 2012, 10:49   #13
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Re: Petrol car to Diesel car conversion - Possible?

Option 3 is most practical and sensible. An in-between option might be installing a CNG kit. I have never been pro CNG but surely its a better option than considering 1 & 2.
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Old 1st June 2012, 11:15   #14
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Re: Petrol car to Diesel car conversion - Possible?

You will have to change the transmission too.
The gear ratios in a vehicle are selected keeping the engine torque-rpm characteristic in mind.

Diesel engine is VERY different from Petrol engine in this.
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Old 1st June 2012, 11:29   #15
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Re: Petrol car to Diesel car conversion - Possible?

No offense to the OP, you seem to have a lot of time on your hands mate. I would have given a thumbs up if it were converting a Petrol Amby/Willys to a diesel. A definite no with the current generation cars.

Quote:
1) What are the pros & cons of doing it?
Only cons unless you have a lot of time and money.
Quote:
2) What are the costs involved.
Almost every single part from the engine/tranny/suspension/ECU et all has to be changed. You can do the math and diesel engines are expensive off the shelf.
Quote:
3) Is it better choice to sell of petrol car & buy a new diesel instead of conversion?
Am glad some sanity prevailed here , sell it and get a diesel car .

Last edited by rjstyles69 : 1st June 2012 at 11:31.
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