"50-MPG" 06 Legacy GT CNG(Natural Gas) build"

So about 8 months ago i decided to convert my 97 LGT to Natural gas Bi-Fuel. I enjoyed the results so much(spending less than a scooter to drive) that I started contemplating converting an STI to natural gas. But all of the STIs that I saw were beat to crap, and then I found a beautiful 06 red LGT, almost identical looking to my other legacy. Well, I bought it and started the conversion process december 26th. It is now december 30th and i am almost done! Now lets see if i can figure out how to post some pictures of the build.

The only major disadvantage I see is that huge CNG tank in the trunk...

I need to see a dyno chart on this.

How well does it run and handle the boost?

I need to see a dyno chart on this.

 

All NGV I've seen are very light on the power.

This will most likely have between 10-15% power loss while running on CNG but the software in the CNG ecu can be set up to seamlessly switch to gasoline when a certain engine load is achieved. The full power of the car will always be available, but it will run on CNG when cruising on the freeway or regular city driving, cutting my fuel cost in half. If I can ever afford a dyno run, i will definitely post it. Im taking my car to get the CNG system tuned today so i should know how it runs in a few days. I will also look into whether cobb can write me a custom map for 130 octane.

What's the cost to convert?

How does the system handle the switch between gas and CNG?

You can convert it yourself for under $1500 if you go with Chinese stuff(but I suggest the polish company zenit, more expensive but extremely high quality, I also suggest that you pay a pro to install it), it depends on what kind of tank you get, that's the expensive part. I bought my stuff from wasatch clean energy and I think their price for them to convert it for you is around $4200(in Utah you get a tax credit to pay for half of the cost so in the end it will be around $2100) with everything included and depending on the vehicle and tank. You cant tell when it switches between the two unless you full on goosing it, than it just fells like an extra turbo just kicked in.

You can convert it yourself for under $1500, it depends on what kind of tank you get, thats the expensive part. I bought my stuff from wasatch clean energy and I think their price for them to convert it for you is around $3500 with everything included and depending on the vehicle. You cant tell when it switches between the two unless you full on goosing it, than it just fells like an extra turbo just kicked in.

 

What are your calculations for the ROI?

On my other CNG subaru had an rough annual fuel saving of roughly $1400 per year so I assume it would be close to that. I think that is what you are asking?

On my other CNG subaru had an rough annual fuel saving of roughly $1400 per year so I assume it would be close to that. I think that is what you are asking?

1400 a year based on how many miles/year?

1400 a year based on how many miles/year?

 

About 15,000 miles a year, I averaged gasoline at about $3.50 and CNG around $1.50 at about 23 MPG. I'm basically paying less than a Prius owner pays to travel, but I get to keep my manhood. I estimate between 50-60 MPG equivalent.

Hey guys, I got the Legacy back and it is running great on CNG. There is a small power loss but only when running on Natural Gas; the CNG tuner says that he can fine tune it so that it is much closer to Gasoline and possibly to the point that no difference can be felt at all. I'm really happy with how this turned out, the legacy is still considerably fast on CNG but it starts to spudder out a little bit at about 5500rpm but the tuner says he will fix that in the tuning software also. Ill be going back to the shop tonight to get that all finished up and then i will be driving from Salt Lake Utah To Lava Hot springs Idaho tomorrow to put it to the test. ill get back to you on Monday with the results. In the mean time, enjoy these pictures of the finished product.

Considering that CNG has a high octane rating (I have seen 130 compared to 92 for gasoline) it seems to me that it might be possible to get some power from the engine by increasing the boost.

 

Just take it step by step though...

Considering that CNG has a high octane rating (I have seen 130 compared to 92 for gasoline) it seems to me that it might be possible to get some power from the engine by increasing the boost.

 

Just take it step by step though...

 

Step by step is definitely the plan, and I do agree with you on more power under boost with the high octane. The problem I'm having with the boost right now is that the CNG injectors I have right now are the largest possible (Cng and performance haven't really been put together before) on my car and each injector maxes out at 60HP(per cylinder) so I'm maxing them out at high rpm. So I have three options; software tuning, put in a second reducer, or try to figure out how to put the diesel NVG injectors inside of my car and trick the software into thinking their normal injectors. I know it's possible but I will just have to figure out which route to take. Step by step!

Dual injectors may be the way to go.

 

I know that they did that in F1 at least during the turbo era.

Man that is great! 1 year pay back and a nice clean setup.

Dual injectors may be the way to go.

 

I know that they did that in F1 at least during the turbo era.

 

How would he run dual injectors?

Please post sources of your materials and instructions on how to do this as a DIY. Pretty neat modification, especially as a bi-fuel option. Would be nice to have the option to go fully CNG if gas prices soar again, but still take advantage of both.

 

Does the software have a 'switch' to put it fully in 'pump gas' or 'cng' mode?

 

Good work!

You know why every car on the planet doesn't run on CNG?

 

The word gas in the name.

Alright! I have good news! So the issue(deleted) I was having was just a mapping problem in my CPU, i took it down to the guys at Wasatch clean energy and they hooked it up to their computer and it turns out I had the pressure on the regulator turned down too low and so my cars computer would try to compensate by making it run too rich causing a weird idle(which makes sense that I was getting a rich code) but we got the pressure back up and all codes are gone and the car runs great now. I still plan on upgrading my regulator to the 400HP regulator because this one just can't keep up under boost it seems like. But thats okay for now because I just have it switch over automatically to gasoline at high RPMs when I want to go fast. But the trip to Idaho went great! Ill start putting together the update and pictures for the trip right now.

mpg figures?

This is cool.

Please post sources of your materials and instructions on how to do this as a DIY. Pretty neat modification, especially as a bi-fuel option. Would be nice to have the option to go fully CNG if gas prices soar again, but still take advantage of both.

 

Does the software have a 'switch' to put it fully in 'pump gas' or 'cng' mode?

 

Good work!

 

I can definitely post some pics of the system,hardware used, and routing options for the system, I can give you simple instructions but by no means am I a professional so if you plan on doing this yourself I suggest you talk you a real CNG pro. So there may be some misconceptions about the system that I put in my car, with this bi-fuel kit it is not running both fuels at the same time, Bi-fuel in this case just means that is is capable of running off one or the other, so yes most the time I am running on CNG. And yes there is a switch to put it fully in to CNG or Fully Pump gas but it also does it automatically if you set it up that way, but both options are always available.

mpg figures?

 

I figure that I'm getting 21 Average MPG while running fully CNG (about 23 on gasoline) but thats just because CNG has less BTU and my timing is not set up for 130 octane, but that may change once I get my hands on an access port and build a custom map for it.