E60 CNG (Natural Gas) conversion
11-25-2012, 09:41 AM
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My Ride: 2006 530I Sport
E60 CNG (Natural Gas) conversion
Hello, I am new to the this site. I just recently picked up a 530i Sport as my daily driver and converted it to run off of CNG (Compressed Natural Gas) or petrol (Bi Fuel). This is very popular in Oklahoma because we have many filling stations and tax credits for the cost of conversions. I am a mechanic by trade and I have a shop where I can convert most any vehicle. Anyhow, I figured it might be one of very few if not the only N52B30 in the states that was converted. This engine seems to like CNG really well as I am getting very similar mileage and power. It was a little challenging to program as there is no manifold vacuum to reference for load when building the fuel map due to the Valvetronic system but I was able to overcome that.
Last edited by brockallentaylor; 11-25-2012 at 10:31 AM.
11-25-2012, 02:06 PM
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My Ride: '06 530i, '07 C280 4matic, '98 ML320
Kudos for taking on a project like this.
How much did it cost to convert N52B30?
How much would the savings be for tank full of gasoline vs. tank full of gas?
For easy comparisons, when I say tank full, let's use 400 miles worth of gasoline vs. the gas.
Are there any drawbacks?
How much did it cost to convert N52B30?
How much would the savings be for tank full of gasoline vs. tank full of gas?
For easy comparisons, when I say tank full, let's use 400 miles worth of gasoline vs. the gas.
Are there any drawbacks?
11-25-2012, 03:40 PM
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The average cost is around $5K for the conversion and we have a 50% state tax credit in Oklahoma and Utah so you're only out $2500. As far as the cost of CNG, it is sold at the pump in a Gasoline Gallon Equivalent or GGE so you don't have to do any math. It is the BTU equivalent of gasoline. Most public stations are around $1.30/GGE but if you put in a small compressor at home that hooks up to your standard natural gas line to fill up you will pay roughly .70 cents per GGE. The only downside is tank size. A tank that fits comfortably in the front of most any trunk is roughly 16x30, weighs around 120lbs but only has a capacity of 6GGE. Conversions are done mostly on trucks and SUV's because they have more room to fit a larger tank. But if you run out of your cheap fuel the system switches back to petrol automatically without interruption, you wont even notice it happened unless you are looking at the little LED readout on the dash for the CNG system. It is a very seamless modern system. Honda sells the Civic GX which is a factory CNG car, but it is the only one. A CNG station map can be found at the website below. Another big upside besides fuel cost and 110 octane is you at least double your oil life. At 5K your oil will look like you just changed it, regardless of the engine type. I run standard Castrol 10w-30 non synthetic in our vans and I change it every 12K or so and it still looks good.
CNG stations and Prices for the US, Canada and Europe
CNG stations and Prices for the US, Canada and Europe
Last edited by brockallentaylor; 11-25-2012 at 03:43 PM.
11-25-2012, 05:14 PM
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About 130 miles. I have a 6GGE tank and average 23 mpg mixed.
I haven't noticed any drop in hwy mileage, I went on a 80 mile all highway drive a few days ago and still got 30 mpg.
Thank you for the complements. I sort of specialize in making universal sequential CNG conversion kits work on most any car. Most of the conversion shops only convert new or near new cars and they like to use vehicle specific kits and there are very few models supported that way. I certainly understand why they do it that way, figuring out where to mount and wire everything and tuning it yourself with no support can be pretty challenging on some engines. That's the part that makes it fun to me though.
I haven't noticed any drop in hwy mileage, I went on a 80 mile all highway drive a few days ago and still got 30 mpg.
Thank you for the complements. I sort of specialize in making universal sequential CNG conversion kits work on most any car. Most of the conversion shops only convert new or near new cars and they like to use vehicle specific kits and there are very few models supported that way. I certainly understand why they do it that way, figuring out where to mount and wire everything and tuning it yourself with no support can be pretty challenging on some engines. That's the part that makes it fun to me though.
Last edited by brockallentaylor; 11-25-2012 at 05:24 PM.
11-25-2012, 07:10 PM
#8
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About 130 miles. I have a 6GGE tank and average 23 mpg mixed.
I haven't noticed any drop in hwy mileage, I went on a 80 mile all highway drive a few days ago and still got 30 mpg.
Thank you for the complements. I sort of specialize in making universal sequential CNG conversion kits work on most any car. Most of the conversion shops only convert new or near new cars and they like to use vehicle specific kits and there are very few models supported that way. I certainly understand why they do it that way, figuring out where to mount and wire everything and tuning it yourself with no support can be pretty challenging on some engines. That's the part that makes it fun to me though.
I haven't noticed any drop in hwy mileage, I went on a 80 mile all highway drive a few days ago and still got 30 mpg.
Thank you for the complements. I sort of specialize in making universal sequential CNG conversion kits work on most any car. Most of the conversion shops only convert new or near new cars and they like to use vehicle specific kits and there are very few models supported that way. I certainly understand why they do it that way, figuring out where to mount and wire everything and tuning it yourself with no support can be pretty challenging on some engines. That's the part that makes it fun to me though.
11-25-2012, 10:48 PM
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I see what you mean, I was not fishing for business in any way. I doubt very seriously I would ever pick up any business from here as I am in Oklahoma and this is not really my target market, I just recently got done with my conversion and wanted to share because I was pretty excited about it, and pretty excited about getting my E60!
This is a condensed version of how the system works.
There is a tank in the trunk that is filled with 4000psi of natural gas whenever you refuel. Refueling takes a similar time as gasoline refueling and even uses a traditional style pump you are currently using, except where you couple the line to the car of course. Don't be concerned about the high pressure tank as far as safety, they have very stringent DOT standards and are much safer than gasoline tanks and can even survive point blank 9mm gunfire.
From there the high pressure gas is sent in a 1/4in line up to the engine compartment where it connects to the reducer (pressure regulator) that takes the gas down from whatever the tank pressure currently is to around 30psi. This reducer is also heated by the engines coolant supply to keep the gas from freezing (due to some moisture content) during the pressure change.
From there the gas is sent though a filter and into an injector rail that is completely independent of the factory injectors. The factory injectors and electronics remain exactly as they were for running the car on gasoline and therefore this system has absolutely no effect on the car while running in gasoline mode. The CNG reducer, filter and injectors can be seen in the pic of my car with the hood open.
Then the CNG flows into jets that are drilled and tapped at strategic locations on the intake manifold determined by the installer. That is it as far as the CNG flow is concerned.
From the electrical standpoint, there is a separate computer (ECU) that runs the CNG injectors. When the vehicle is started it always starts on gasoline. Once the CNG computer reads that the regulator has sufficient coolant temperature the system begins to engage.
One injector at a time the system will intercept the gasoline injector and redirect its pulse into the CNG computer where it will be read and translated though a fuel correction table much like a standard fuel map. This map basically applies a correction factor to the pulse to make it appropriate for the larger CNG injector. There are many other factors that act on the table such as CNG injector rail temperature and pressure.
The clever part is that through this method, the factory BMW ECU still has full control over the CNG injector and therefore all emissions systems function as they did because the pulse is only corrected. The factory ECU is still trimming the CNG injectors and controlling all the systems the way it always did, so there are no check engine light issues as long as the tuning is done correctly.
Because of this new-ish design and the fact that the injector signals are slowly switched over to the CNG injectors one at a time (over a 5 second period or so) means that a seamless transfer can be made between gasoline and CNG back and fourth. When the system engages and disengages and you are underway there will be no noticeable change to the driver. When you run out of CNG while driving the computer will sense the pressure drop in the rail and switch back to gasoline without any effect on the driver even if you are under acceleration.
There are other components to the system that cannot be seen under the hood as they are hidden away as they should be, and any wire connections are routed and connected in the most discreet manner possible so that to the naked eye there does not seem to be much going on, but getting things that way takes patience and attention to detail and you will find not all systems are equal, and not all installs are equal, and therefore not all satisfaction rates are equal. All of my customers absolutely love filling their vehicles up with CNG. It feels pretty great filling up when everyone else at the station is paying more than double per gallon equivalent. Plus you are guaranteed to be approached by other CNG drivers while fueling. Sort of a nerd bonding I guess. Certainly not the usual I'm here to get taken to the cleaners by a foreign nation feeling you used to get.
I have tried to point out a few things in this writeup simply for the sake of correcting a lot of misinformation that is out there concerning CNG. If you do a lot of on line research you will find a bunch of people that will disregard it due to them having the previous mechanical type of CNG conversions that are much cheaper, out dated and far less effective. These modern systems are designed so there is no learning curve except connecting the fuel nozzle to fill up and looking at a 1in LED readout mounted wherever you want that shows the level of CNG in the tank and what fuel you are currently using. I have converted vehicles for people that could not change a flat tire and they have no issues managing.
Of course for this to work you need to live in an area that has convenient CNG filling stations as we do here in Oklahoma or you need to have a small CNG compressor installed at your house in the garage as many people do that will fill your tank with natural gas at night from the same source that heats your house possibly. You would also have to look at how long it would take to get a return on your investment which will vary greatly depending on what you are going to pay for natural gas and how many miles you drive per year. ROI can take anywhere from 3 months to 2 years depending on your situation. Most people break even around 1 year in this area and some commercial use pickups as little as 4 months. Most conversions I do fall in the 5-6k out the door range and each states tax incentives are different, some as high as 65% of the conversion cost. Did I mention you lower your tailpipe emissions by a HUGE amount and have to change your oil far less? Okay now I'm starting to sound like a salesperson but I think that is a very nifty bonus to saving money.
Whew, I'm up past my bedtime.
This is a condensed version of how the system works.
There is a tank in the trunk that is filled with 4000psi of natural gas whenever you refuel. Refueling takes a similar time as gasoline refueling and even uses a traditional style pump you are currently using, except where you couple the line to the car of course. Don't be concerned about the high pressure tank as far as safety, they have very stringent DOT standards and are much safer than gasoline tanks and can even survive point blank 9mm gunfire.
From there the high pressure gas is sent in a 1/4in line up to the engine compartment where it connects to the reducer (pressure regulator) that takes the gas down from whatever the tank pressure currently is to around 30psi. This reducer is also heated by the engines coolant supply to keep the gas from freezing (due to some moisture content) during the pressure change.
From there the gas is sent though a filter and into an injector rail that is completely independent of the factory injectors. The factory injectors and electronics remain exactly as they were for running the car on gasoline and therefore this system has absolutely no effect on the car while running in gasoline mode. The CNG reducer, filter and injectors can be seen in the pic of my car with the hood open.
Then the CNG flows into jets that are drilled and tapped at strategic locations on the intake manifold determined by the installer. That is it as far as the CNG flow is concerned.
From the electrical standpoint, there is a separate computer (ECU) that runs the CNG injectors. When the vehicle is started it always starts on gasoline. Once the CNG computer reads that the regulator has sufficient coolant temperature the system begins to engage.
One injector at a time the system will intercept the gasoline injector and redirect its pulse into the CNG computer where it will be read and translated though a fuel correction table much like a standard fuel map. This map basically applies a correction factor to the pulse to make it appropriate for the larger CNG injector. There are many other factors that act on the table such as CNG injector rail temperature and pressure.
The clever part is that through this method, the factory BMW ECU still has full control over the CNG injector and therefore all emissions systems function as they did because the pulse is only corrected. The factory ECU is still trimming the CNG injectors and controlling all the systems the way it always did, so there are no check engine light issues as long as the tuning is done correctly.
Because of this new-ish design and the fact that the injector signals are slowly switched over to the CNG injectors one at a time (over a 5 second period or so) means that a seamless transfer can be made between gasoline and CNG back and fourth. When the system engages and disengages and you are underway there will be no noticeable change to the driver. When you run out of CNG while driving the computer will sense the pressure drop in the rail and switch back to gasoline without any effect on the driver even if you are under acceleration.
There are other components to the system that cannot be seen under the hood as they are hidden away as they should be, and any wire connections are routed and connected in the most discreet manner possible so that to the naked eye there does not seem to be much going on, but getting things that way takes patience and attention to detail and you will find not all systems are equal, and not all installs are equal, and therefore not all satisfaction rates are equal. All of my customers absolutely love filling their vehicles up with CNG. It feels pretty great filling up when everyone else at the station is paying more than double per gallon equivalent. Plus you are guaranteed to be approached by other CNG drivers while fueling. Sort of a nerd bonding I guess. Certainly not the usual I'm here to get taken to the cleaners by a foreign nation feeling you used to get.
I have tried to point out a few things in this writeup simply for the sake of correcting a lot of misinformation that is out there concerning CNG. If you do a lot of on line research you will find a bunch of people that will disregard it due to them having the previous mechanical type of CNG conversions that are much cheaper, out dated and far less effective. These modern systems are designed so there is no learning curve except connecting the fuel nozzle to fill up and looking at a 1in LED readout mounted wherever you want that shows the level of CNG in the tank and what fuel you are currently using. I have converted vehicles for people that could not change a flat tire and they have no issues managing.
Of course for this to work you need to live in an area that has convenient CNG filling stations as we do here in Oklahoma or you need to have a small CNG compressor installed at your house in the garage as many people do that will fill your tank with natural gas at night from the same source that heats your house possibly. You would also have to look at how long it would take to get a return on your investment which will vary greatly depending on what you are going to pay for natural gas and how many miles you drive per year. ROI can take anywhere from 3 months to 2 years depending on your situation. Most people break even around 1 year in this area and some commercial use pickups as little as 4 months. Most conversions I do fall in the 5-6k out the door range and each states tax incentives are different, some as high as 65% of the conversion cost. Did I mention you lower your tailpipe emissions by a HUGE amount and have to change your oil far less? Okay now I'm starting to sound like a salesperson but I think that is a very nifty bonus to saving money.
Whew, I'm up past my bedtime.
Last edited by brockallentaylor; 11-25-2012 at 10:58 PM.
11-26-2012, 02:14 AM
#10
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Excellent info! The only drawback i see is the storage. The 550 would empty that 6GG tank out in 90 miles around town, 150 on the highway. The obvious big plus though is that its so much cheaper to run.