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Old 2nd August 2006, 04:40   #1
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Arrow Carb/MPFI - Which is having longer engine life ?

Among Carb & MPFI vehicles, Which is having longer engine life ? I've heard conflicting opinions from people regarding this.

Among Carb & MPFI vehicles, which is having high maintenance cost in overall ?

Why the new Omni LPG comes with a carburettor than with a MPFI engine but WagonR LPG comes with a MPFI engine ? Maruti is citing that for LPG, carb is better and is having longer engine life. Is there any truth in this statement ?

I know a lot of MPFI running hassle free with LPG.
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Old 2nd August 2006, 18:53   #2
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I understand that the vibrations are less compared to a regular engine. Each cylinder is provided a uniform amount of fuel and air mixture. Hence the power difference doesnt exist. Firing in each cylinder is also controlled by this uniformity. This could advance engine life.

Too much cranking the engine when it is cold can also be avoided thereby increasing the starter and other component's life. This is my layman's perception of MPFI. Expert opinions are awaited.
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Old 2nd August 2006, 19:51   #3
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Carbs have lower maintenance costs, but higher service intervals. MPFI's have lower intervals, but higher costs.

An MPFI engine will definitely last longer due to better overall running efficiency, but it will be costlier to maintain in the long run.
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Old 5th August 2006, 06:08   #4
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For example, when comparing a car like M800/Omni, which one among Carb/MPFI gives more FE ?
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Old 5th August 2006, 07:06   #5
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MPFI will give more FE.
Also MPFI will be better for the engine.
In extreme conditions the carburettor may get flooded, stall the engine, but in case of MPFI the load will be on the Fuel pump.
This is the only major component which is taxed more in case of MPFI. As far as engine is concerned, MPFI keeps it healthier.
Another factor is adulterated fuel. Adulterated fuel clogs the carb and cleanup and repair is cheap, but in case of MPFI repair will be expensive. But then running on adulterated fuel on a carb will cause more damage to engine then running on MPFI.
If you look at typical life of 87 octane engines from honda etc., running on MPFI, its like 200,000-300,000 miles without overhaul.
What Maruti has done is keep costs low.
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Old 5th August 2006, 07:55   #6
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Quote:
Originally Posted by veyron1
Carbs have lower maintenance costs, but higher service intervals. MPFI's have lower intervals, but higher costs.
veyron, do you mean higher interval or higher frequency?

higher interval = more time between services, so the carb would have lower maint costs, and more time between services.
Similarly for MPFI engines - higher maintenance, and services are also sooner.

Is this what you meant to say? pls clafiry
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Old 5th August 2006, 10:55   #7
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@Condor:No, I meant the other way round. Carbs have higher frequency, and the MPFI's otherwise. Which means MPFI's have longer, not lower service intervals...yeah, that sounds better. Thanks for pointing it out.
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Old 8th August 2006, 06:10   #8
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Quote:
Why the new Omni LPG comes with a carburettor than with a MPFI engine but WagonR LPG comes with a MPFI engine ? Maruti is citing that for LPG, carb is better and is having longer engine life. Is there any truth in this statement ?
Anyone please answer the above question also...
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Old 8th August 2006, 06:31   #9
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Quote:
Originally Posted by mithun
Anyone please answer the above question also...
Its pure BS. Actually in the days of leaded fuel, LPG vs Leaded fuel argument was given as lead used to work as a lubricant. When you are talking about unleaded fuel there is little difference. The only thing here is that sometimes it is advised to run the engine on petrol till its warm and then switch over to LPG to prevent something called the freezing effect, but it has nothing to do with Carb and MPFI. Maybe what they mean is that the freezing effect will cause more damage to MPFI engine if it happens.
But the actual reason is saving cost. Carburettor is cheaper, so they will give all kinds of excuses. If Euro II had not come maruti will still be selling carb esteems and claiming that carburettor engines are better than MPFI engines(This was part of the dealership campaign against santro when zen(carb) and santro(MPFI) arguments were brought up.
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Old 8th August 2006, 14:42   #10
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Quote:
Originally Posted by veyron1
@Condor:No, I meant the other way round. Carbs have higher frequency, and the MPFI's otherwise. Which means MPFI's have longer, not lower service intervals...yeah, that sounds better. Thanks for pointing it out.
could be based on cars of particular model and most important quality of fuel. my carb version nissan has not had a service since i bought it in 4+yrs of use.
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Old 20th August 2006, 16:54   #11
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When I went to a TrueValue outlet yesterday, I overheard a salesman canvassing a customer who came to buy a Zen (which he plans to fit LPG) saying at the Carb Zen is better than the MPFI Zen in all aspects for fitting LPG and carb Zen can be tuned for mileage/performance and in MPFI there is no such possibility and if the mileage got reduced for any reason you have to bear it and nothing can be done except the Injector cleaning !!!

And if the MPFI's are soooo bad, I'm wondering why Maruti is selling MPFI vehicles ???
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Old 20th August 2006, 18:30   #12
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I think for the sake of Pollution they are selling MPFI

Coz MPFI engines gives less pollution

Correct me if i am wrong...
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Old 20th August 2006, 18:58   #13
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Quote:
Originally Posted by mithun
And if the MPFI's are soooo bad, I'm wondering why Maruti is selling MPFI vehicles ???
OMG!... man! how can you ignore the clear 10bhp addition that zen had!... which made the car so much more drivable.
MPFI and carbs can't even be compared...
just b'coz maruti guys are actually incompetent to do any kind of tuning on any car its not MPFI's fault.

Quote:
Originally Posted by rareone
I think for the sake of Pollution they are selling MPFI

Coz MPFI engines gives less pollution

Correct me if i am wrong...
Yes thats what made them sell it in the first place... but that's not the only advantage.

Also as we have already discussed in this thread.... "better engine life"... what more!
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Old 20th August 2006, 20:55   #14
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Quote:
Originally Posted by mithun
When I went to a TrueValue outlet yesterday, I overheard a salesman canvassing a customer who came to buy a Zen (which he plans to fit LPG) saying at the Carb Zen is better than the MPFI Zen in all aspects for fitting LPG and carb Zen can be tuned for mileage/performance and in MPFI there is no such possibility and if the mileage got reduced for any reason you have to bear it and nothing can be done except the Injector cleaning !!!

And if the MPFI's are soooo bad, I'm wondering why Maruti is selling MPFI vehicles ???
A Carb Zen is definitely better than the MPFI Zen (for LPG)...not only because it can be tuned accordingly BUT because it has a Compression ratio of 8.8:1 where as MPFI Zen has Compression ratio of 9.4:1. LPG fitted cars need lesser air to run the engine the MPFI needs more air to run the engine. So if LPG is fitted in an MPFI engine we can not restrict Air (because when MPFI Zen is on petrol it will run into problems) but we will have to pour in more gas to achieve lower Compression ratio. LPG is delivered as a vapor to the engine. The other reason is that LPG has a lower percentage of Octane so using it in a higher Compression engine would not result in best performance.
Ok..there is one more logic here...to get best performance from an LPG run engine we have to tweak the timing of ignition which can not be done on an MPFI engine.
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Old 20th August 2006, 21:48   #15
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the carbs are any day better than mpfi (((IN INDIA)))) if u are a person who tanks up at any bunk available. assuming ur car does a max of 180kmph which happens occassional so most of the time if u r cruising at 100kmph i personally feel that whether its carb or mpfi theres not much strain on the engine.

and yes lower the compression more the engine life ofcourse at some colateral expense.
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