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CNG conversion (1 Viewer)
- Thread starter livelarg
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OK, now that we've sorted out the basics of what CNG is vs LPG, here's a design question that might suggest how you'd go about this. Since CNG is stored at a much higher pressure, the biggest difference between the it and LPG is dealing with stepping that pressure down so the fuel system can use it.
Is the pressure regulator on these part of the fuel system, i.e. under the hood, i.e. is it a discrete part, say located on or next to the tank? One way requires a lengthier high pressure line to go under the hood, while the second only feeds low pressure gas forward to the motor. I'm guessing it's the second, as it seems safer, but maybe someone who's seen an install can tell us more?
Is the pressure regulator on these part of the fuel system, i.e. under the hood, i.e. is it a discrete part, say located on or next to the tank? One way requires a lengthier high pressure line to go under the hood, while the second only feeds low pressure gas forward to the motor. I'm guessing it's the second, as it seems safer, but maybe someone who's seen an install can tell us more?
I'll provide some info on how things look like over the pond.
LPG equipment costs are around $500-1500 (incl. labor) depending on type of vehicle and included components. CNG costs twice as much to install.
A complete CNG/LPG install includes the following:
- tank
- pressure regulator
- filters
- evaporator
- ECU
Yes, there is an ECU which connects to the same things the gasoline ECU does: injectors, o2 sensors, MAF, temperature sensors, etc... So running on LPG/CNG is not from a fixed map but from real life engine data. At the same time the OEM ECU is turned off or fooled so that it doesn't record 'stupid' data from LPG/CNG operation. This is important as it doesn't affect long term and short term fuel trim while switching back to gasoline. The switch from gasoline to LPG and vice versa is unnoticeable, sometimes just a slight hesitation that lasts a milisecond because the ECU can control both the gasoline and gas injectors to provide a smooth transition.
There are no safety problems with LPG/CNG. The systems are basically foolproof and I have heard probably of one or two accidents, fires in my life. Both were very old rotten cars and their owners simply installed illegally old rusty tanks for $20 instead of buying a brand new tank for $100. But not casualties, just a fried vehicle.
So far the only problem for LPG/CNG is gas stations. LPG is a standard in most European countries (and probably Australia) and 90% of gas stations have LPG available. CNG is more of a problem but becoming gradually more available.
I assume that in the US this is still in very early stages. Gasoline is cheap so there is no reason to introduce LPG/CNG to the market.
LPG equipment costs are around $500-1500 (incl. labor) depending on type of vehicle and included components. CNG costs twice as much to install.
A complete CNG/LPG install includes the following:
- tank
- pressure regulator
- filters
- evaporator
- ECU
Yes, there is an ECU which connects to the same things the gasoline ECU does: injectors, o2 sensors, MAF, temperature sensors, etc... So running on LPG/CNG is not from a fixed map but from real life engine data. At the same time the OEM ECU is turned off or fooled so that it doesn't record 'stupid' data from LPG/CNG operation. This is important as it doesn't affect long term and short term fuel trim while switching back to gasoline. The switch from gasoline to LPG and vice versa is unnoticeable, sometimes just a slight hesitation that lasts a milisecond because the ECU can control both the gasoline and gas injectors to provide a smooth transition.
There are no safety problems with LPG/CNG. The systems are basically foolproof and I have heard probably of one or two accidents, fires in my life. Both were very old rotten cars and their owners simply installed illegally old rusty tanks for $20 instead of buying a brand new tank for $100. But not casualties, just a fried vehicle.
So far the only problem for LPG/CNG is gas stations. LPG is a standard in most European countries (and probably Australia) and 90% of gas stations have LPG available. CNG is more of a problem but becoming gradually more available.
I assume that in the US this is still in very early stages. Gasoline is cheap so there is no reason to introduce LPG/CNG to the market.
I also plan to do a CNG conversion. I live in Utah and I have a buddy who has done conversions on several Toyotas (Avalon and Tacoma). He also has an Excursion that he runs with 3 tanks and something like 30 gallon capacity.
Here is what I have learned so far. There are two kinds of kits. One is a fogger type which my buddy uses. The other is an injected type. The fogger type is much cheaper. It uses a regulator near the intake manifold and fogs the natural gas into the air intake. You have to have a shut off value on the tank and high pressure lines throughout. The fogger uses an electronic device that turns off the gasoline fuel injectors when it starts fogging. I believe you still use the normal ECM but don't quote me on that I could be wrong. You also have to start the vehicle on gasoline and switch over when it warms up.
The direct injected kit costs significantly more and also is much more complex. I know it uses its own ECM that has to be tuned specifically for the vehicle. You have to drill holes into the intake manifold to install the natural gas injectors. That is about all I know about this type.
I plan on buying my tanks from americancng.com because they are in Utah, and the kit from someone my buddy knows. If you want I can find out if his source has a web site. I also plan to install the tanks where the spare tire goes but I am waiting until I can get a rear bumper. I just did sliders so I am saving for the bumper.
Here is what I have learned so far. There are two kinds of kits. One is a fogger type which my buddy uses. The other is an injected type. The fogger type is much cheaper. It uses a regulator near the intake manifold and fogs the natural gas into the air intake. You have to have a shut off value on the tank and high pressure lines throughout. The fogger uses an electronic device that turns off the gasoline fuel injectors when it starts fogging. I believe you still use the normal ECM but don't quote me on that I could be wrong. You also have to start the vehicle on gasoline and switch over when it warms up.
The direct injected kit costs significantly more and also is much more complex. I know it uses its own ECM that has to be tuned specifically for the vehicle. You have to drill holes into the intake manifold to install the natural gas injectors. That is about all I know about this type.
I plan on buying my tanks from americancng.com because they are in Utah, and the kit from someone my buddy knows. If you want I can find out if his source has a web site. I also plan to install the tanks where the spare tire goes but I am waiting until I can get a rear bumper. I just did sliders so I am saving for the bumper.
My 80 came from Oklahoma with cng installed by the po. I'm currently sourcing a tank to replace the one that is no longer there which was located in the spare tire location underneath the rear passenger area. I have an impco class E regulator, and a couple of computers, a fill nozzle, a shut off valve, a tank selector switch, and various other parts.
I fully intend to get it operational soon, my only hang up is that the nearest filling station is nearly 30 miles away, so I need to determine my range on the largest tank I can realistically fit to determine if its practical for my application. The fact that my cost per gallon will equate to about 37mpg is very appealing!
I'll try to post pics of the components of my system later if anyone's interested.
Btw my system isn't injected, but is a more primitive system.
I fully intend to get it operational soon, my only hang up is that the nearest filling station is nearly 30 miles away, so I need to determine my range on the largest tank I can realistically fit to determine if its practical for my application. The fact that my cost per gallon will equate to about 37mpg is very appealing!
I'll try to post pics of the components of my system later if anyone's interested.
Btw my system isn't injected, but is a more primitive system.
I suspect that two smaller diameter tanks would fit better than one large diameter tank and would give better ground clearance. I also believe that you have to use all steel tanks (type 1) when they are placed under the vehicle. Something about moisture problems and potential damage to the wrappings on the other types of tanks. It might be a good idea to add a skid plate anyway.
There are many used tanks for sell and some people use those. They tend to be ones that are near the end date of use before they need to be re-certified. Some have said that these tanks are very over engineered. I will probably pay the extra money for new ones as trusting on over engineering is not my style.
There are many used tanks for sell and some people use those. They tend to be ones that are near the end date of use before they need to be re-certified. Some have said that these tanks are very over engineered. I will probably pay the extra money for new ones as trusting on over engineering is not my style.
I've considered using multiple tanks, even downsizing my gasoline tank to accomodate additional tanks. I need to know how much space in ft3 is needed to yield a range of 200 + mi per tank at 12 mpg. I really would like to have at least that much range, or it won't really benefit my driving needs. Does anyone know the conversion of the volume of CNG GGE to a gallon of gasoline?
You're absolutely correct. It's funny when I re-read what I wrote I was thinking that something was off...
Thanks for setting the record straight.
You will have to do the lb,ft,gal maths, here is the metric stuff, a riddle actually:
One liter of gasoline gives you a similar range as a cubic meter of CNG.
A 10 liter CNG tank can be filled only with 4 square meters of CNG. A 100 liter CNG tank takes 40 square meters of CNG etc.
Thant's what I've found on a CNG forum so don't quote me on that but the information is probably right.
The FZJ80 usually needs 20 liters per 100km so that's 60 liters per 300km or 200miles. 60 liters is roughly 16 gallons per 200mi.
You will pobably need a 32-36 gallon tank for that range. These are some calculations off my head (and I've always had problems with maths) so you need to calculate on your own.
One liter of gasoline gives you a similar range as a cubic meter of CNG.
A 10 liter CNG tank can be filled only with 4 square meters of CNG. A 100 liter CNG tank takes 40 square meters of CNG etc.
Thant's what I've found on a CNG forum so don't quote me on that but the information is probably right.
The FZJ80 usually needs 20 liters per 100km so that's 60 liters per 300km or 200miles. 60 liters is roughly 16 gallons per 200mi.
You will pobably need a 32-36 gallon tank for that range. These are some calculations off my head (and I've always had problems with maths) so you need to calculate on your own.
- Thread starter
- #30
This is the only kit that I found. http://www.cngsrus.com/ProductDetails.asp?ProductCode=K0003
As much as they are saying CNG is so good, it is really not easy to find stuff. Next is to find the different sizes, and prices of tanks.
Superstan: would love to see pics of your system
As much as they are saying CNG is so good, it is really not easy to find stuff. Next is to find the different sizes, and prices of tanks.
Superstan: would love to see pics of your system
- Thread starter
- #31
craigslist showed some used tanks in the $500-$1000 price range for 10-16 gge sizes.
Here is info on weights of the type 4 tanks, the lightest ones.
http://www.natemax.com/products/cng-tanks/cng-tanks-type-4/
Here is info on weights of the type 4 tanks, the lightest ones.
http://www.natemax.com/products/cng-tanks/cng-tanks-type-4/
ewsews.com or cng-america.com or americancng.com/cylinders.html. I have never used either and I can't vouch for their services or products.
I think type 4 can't go inside the vehicle because it is plastic and it slowly seeps gas so you would smell it. I don't know how it would do under the vehicle. I guess plastic doesn't corrode so it might work.
Also try ksl.com and search the classified section. That is a local Utah site with many used tanks and installers.
I think type 4 can't go inside the vehicle because it is plastic and it slowly seeps gas so you would smell it. I don't know how it would do under the vehicle. I guess plastic doesn't corrode so it might work.
Also try ksl.com and search the classified section. That is a local Utah site with many used tanks and installers.
Regarding the range you can expect, look at the GGE (gasoline gallon equivalent) for an idea of the energy the tank can hold. However, and this is from my friend's setups, you can never use all the natural gas in the tank. You have to plan for about 10 to 15 percent that will stay in the tank when the pressure drops too low for the system to effectively function. The motor will start to hesitate and you have to switch to gasoline.
I would guess you need about 20 GGE to go 200 miles but that is without doing the riddle math previously mentioned. I would try to find tanks that would fit in the space you have. It might be hard to fit that much underneath. If you don't mind losing space in the back, you could put a tank inside. Just make sure you install it the right way with the sleeves over the tubing so if there is a leak it goes outside the cab.
I would guess you need about 20 GGE to go 200 miles but that is without doing the riddle math previously mentioned. I would try to find tanks that would fit in the space you have. It might be hard to fit that much underneath. If you don't mind losing space in the back, you could put a tank inside. Just make sure you install it the right way with the sleeves over the tubing so if there is a leak it goes outside the cab.
- Thread starter
- #34
As far as range goes, even if you get 150 miles per tank, depending on Joe much you drive is still a big savings. I'm getting 11-12 mpg now. At gas at even 3.50, That's almost $35-40 buck in gas. And only maybe $20 in CNG. That saves me almost $80-100 in fuel a month. Sometimes more.
Since you can switch from CNG to gas. I don't have to always be running to refill the CNG. And refill is only 3 miles from my house.
On longer trips. Just look ahead and see we're to fill up.
Since you can switch from CNG to gas. I don't have to always be running to refill the CNG. And refill is only 3 miles from my house.
On longer trips. Just look ahead and see we're to fill up.
Thanks for all of the info concerning mpg volume and such. I understand the obvious savings on mpg, but my concern is that with the only fill up station being 30 miles one way and only having a 200 ish mile capacity that would obviously cut into savings, and range substantially. It doesn't negate the fact that my main reason for purchasing the cruiser was as a second vehicle that I could drive on off road excursions to the west where cng seems to be much more abundant. I have no doubt that I'll eventually get it operational, but for now I'm just enjoying the ride, and the build.
My following posts will be of components in the system I have which is slow pressure system I believe my friend stated 2800 psi. And one pic of my cruiser a work in progress!
My following posts will be of components in the system I have which is slow pressure system I believe my friend stated 2800 psi. And one pic of my cruiser a work in progress!
- Thread starter
- #38
Here is some other info on kits, and a video explaining it.
The simple mix kit is fairly cheap, about $600. And it connects right before the intake manifold. It works as a single nozzle injection and cuts off the fuel injectors when CNG is in use. Yo ucan switch between fuels at will.
Still trying to size tanks and see what will fit under truck.
Kit: http://ews.mybigcommerce.com/millen...r-fuel-injected-gasoline-engines-model-cngm6/
Video: http://www.youtube.com/watch?v=ltNGsFVwSjQ&feature=youtu.be
The simple mix kit is fairly cheap, about $600. And it connects right before the intake manifold. It works as a single nozzle injection and cuts off the fuel injectors when CNG is in use. Yo ucan switch between fuels at will.
Still trying to size tanks and see what will fit under truck.
Kit: http://ews.mybigcommerce.com/millen...r-fuel-injected-gasoline-engines-model-cngm6/
Video: http://www.youtube.com/watch?v=ltNGsFVwSjQ&feature=youtu.be
The Miellennium Kit looks interesting.
How do you contact them? Do you have to subscribe to contact them?
Wonder how it works with OBD1 engines?
How do you contact them? Do you have to subscribe to contact them?
Wonder how it works with OBD1 engines?
