08-07-2022, 09:35 PM
Hi Richard,
Regarding fuel milage data, thats complicated. The problem that existed was a restricted intake system due to an undersized intake pipe which is similar in some ways to lifting your foot off the accelerator. So it could be argued that a possible increase in fuel milage should be expected as you're engine is making less HP so you're driving slower. I did not notice any better milage, however, I did modify my driving technique and more carefully restricted my speed closer to the optimal 1275 RPM which if I remember correctly gave me about 62 MPH. The problem is this coach is so heavy especially when towing my 4x4 Chevy Silverado that any slight hill really makes a difference and comparisons almost impossible. I was especially surprised on my last big drive from Phoenix to Fairhope, Alabama taking the southernly route I10 that my milage was only a bit better then when driving at the speed limit. Somewhere in the 5.6 to 5.8 MPG vs 5.2 to 5.3 in the past. I have hit the 6's however that really required flat roads like those in Florida.
I should also mention that restricting airflow by having a piece of ducting that is overly restrictive is not the same as lifting your foot off the accelerator. The MAS is what keeps the engine running at the proper air/fuel ratio, other than that all of the pressures within the intake ductwork are running out of specification and in the case of the turbos they can run such high vacuum pressures at the seals that seal failure is a risk.
If you want to know what the actual number are for these coaches then a Dyno is required. I have been looking to get mine on a dyno but no one I asked was interested it trying to get an RV onto there rig.
Another thought I just had is that my last trip involved some different thinking. First, I kept my fuel tank full fearing I might run into an area that was short on fuel. I also kept my pantry fully stocked and even the toad was fully fueled and loaded. All this effects milage.
The additional positive effects my modification has done is to significantly reduced air intake temperatures by insulating all piping and even the air filter. Pulling cooler fresh air from the passenger side engine louvre and continually monitoring the air intake, oil temp and water temp, also allowed me to modify my driving on the fly depending on the instrument feedback.
The mod is worth doing as power will come into line with factory specs and the turbos will now be at their proper pressures. You will also eliminate the chance of ingesting water and keep your filter dry.
I will make another video when I have something new to show.
Best Regards to all.
Mike
Regarding fuel milage data, thats complicated. The problem that existed was a restricted intake system due to an undersized intake pipe which is similar in some ways to lifting your foot off the accelerator. So it could be argued that a possible increase in fuel milage should be expected as you're engine is making less HP so you're driving slower. I did not notice any better milage, however, I did modify my driving technique and more carefully restricted my speed closer to the optimal 1275 RPM which if I remember correctly gave me about 62 MPH. The problem is this coach is so heavy especially when towing my 4x4 Chevy Silverado that any slight hill really makes a difference and comparisons almost impossible. I was especially surprised on my last big drive from Phoenix to Fairhope, Alabama taking the southernly route I10 that my milage was only a bit better then when driving at the speed limit. Somewhere in the 5.6 to 5.8 MPG vs 5.2 to 5.3 in the past. I have hit the 6's however that really required flat roads like those in Florida.
I should also mention that restricting airflow by having a piece of ducting that is overly restrictive is not the same as lifting your foot off the accelerator. The MAS is what keeps the engine running at the proper air/fuel ratio, other than that all of the pressures within the intake ductwork are running out of specification and in the case of the turbos they can run such high vacuum pressures at the seals that seal failure is a risk.
If you want to know what the actual number are for these coaches then a Dyno is required. I have been looking to get mine on a dyno but no one I asked was interested it trying to get an RV onto there rig.
Another thought I just had is that my last trip involved some different thinking. First, I kept my fuel tank full fearing I might run into an area that was short on fuel. I also kept my pantry fully stocked and even the toad was fully fueled and loaded. All this effects milage.
The additional positive effects my modification has done is to significantly reduced air intake temperatures by insulating all piping and even the air filter. Pulling cooler fresh air from the passenger side engine louvre and continually monitoring the air intake, oil temp and water temp, also allowed me to modify my driving on the fly depending on the instrument feedback.
The mod is worth doing as power will come into line with factory specs and the turbos will now be at their proper pressures. You will also eliminate the chance of ingesting water and keep your filter dry.
I will make another video when I have something new to show.
Best Regards to all.
Mike
2008 Newell #1223 4 slide, Cat C15 with ZF 12 spd, 2004 Chevy Silverado 4x4 Duramax 6.6