Southpole560

That's pretty dang good fuel economy! You can't even get anywhere near that in a new truck. One of the reasons why I'm gonna stick with my 2nd gen. Apparently those 245s came stock on my truck according to the door sticker. Why didn't the last owner just keep those on? Would have saved me the trouble

Once my 35s wear out, I'll be going to either a 32 or 33. Might even change the gearing if I have to. There have been some articles that I've read where people say they have gotten around the 20-22mpg mark with 35 inch tires and same gearing but I just don't see how it's possible especially going faster. If I kept my rpms around 1800-2000 going a bit faster, would I just be using more fuel with those 35s and having a drop in mpgs? That's what I've always thought. I just don't really drive 75-80 that often.

I've wondered the same thing since I have 35's. After I installed the 7x.010 injectors, my load has gone down about 5-8% and I noticed a slight drop in egts but that could have been from a tail wind. I think the percentage drop may be from the pop pressure being set at 320 bar though. My best mileage so far has been 18.9 tank average with 18.5° timing @ 1650 rpm going 65 mph. I'm starting to experiment now with the lower timing values but my egts have gone up a little which is making me think that this tank average will be a bit lower but I guess I'll see. Here's a really good article I found. It doesn't pertain to the Cummins engine but it does have a lot of good information on timing, cetane, etc that I believe we can put to use. http://www.maxxtorque.com/2009/03/diesel-timing.html?m=1

Do you know if it drops down to 42 in summer? I probably shouldn't be using a cetane booster with the B20 over here. I'm starting to think that it makes my fuel economy worse.

I'm at 700-750 now with the lower timing instead of around 650 with timing advanced around 18-19. Do you know what your winter cetane number is over there in Idaho?

If I get the timing right, should I see a low engine load, low oil temp, and low egts? I'm trying the winter economy tune with a 2° cruise timing advance instead of 1° but it seems like my egts have gone up as opposed to higher timing with lower egts. Can good mpgs be had with a slight increase in egts regarding the lower timing?

I have a viton o-ring assortment that hopefully will work. The adapter said it came with a crush washer though. Should I just use that o-ring then instead?

I just got an adapter ordered. Will a crush washer work instead of an o-ring or will I definitely need that o-ring?

Do you know what size it is? If it's 1/4 I might be able to get an adapter and relocate my oil pressure sensor there so I can put the temp probe in the filter housing.

Do you know if there are any other oil ports on the 24v where I can install a 1/8 npt temp probe? The only one I know of is the port above the oil filter housing but I have my oil pressure sender installed there.

Is there a way that I can find the optimal timing for my engine with the high cetane fuel? Will I just have to study the load % and EGT? I have been running at 16* lately but it seems that my egts have gone up a bit. Would this indicate too low of timing? I've tested out higher timing 20+ but it seems that I don't really get any improvement and that I might be getting a negative torque result. Not sure but that's what I'm thinking.

So I just found out that the local supplier here in Oregon (SeQuential), that supplies fuel to the Shell station I usually go to, has a cetane rating of 55.3 for their B100. They cut it with regular #2 diesel to make it B20. The cetane rating should then be about 50 for the B20. All the research that I've done states that B20 should be right about there. My question is, what timing would be the best for this 50 cetane fuel? I normally drive at 60-65 and my rpms are ~1550-1675. Should I be around 16* cruise timing for max fuel economy with this fuel or is that too low/high?

What tuning file are you using and what speed are you mainly cruising at?

What mpgs are you pulling with your setup and a light foot?

How long have you had those injectors for?

I don't really have an option to take the tools out. I unfortunately live in a semi truck (truck driver) and don't have the space for anything. But a house is in the near future! And a new job lol. What cetane rating do you have in Idaho? I know in Oregon the specifications are no less than 47 cetane but I'm not sure what the rating is for B20 that I get at the shell station. I'm thinking it might be a bit higher than 47 at that shell. I've gotten the fuelling on your eco tune down pretty well to accommodate my RV275's, but I still think my timing is slightly off. That run where I got 18.9mpg going to Pendleton was with the advancement dropped down to 2° from the original 3°. I currently have it at 2.4 but am thinking if I should possibly drop it a bit lower than 2 and see how that plays out with the B20. Should I just be adjusting the base timing instead of the cruise timing?

I wonder how much timing it adds to stock. That would be interesting to see.

Try setting the light throttle advancement to 2°. I personally have my light throttle load limit set to 33% and have seen alright results. Last trip I took I got 18.9mpg tank average going from Portland to Pendleton, OR and had cruise set at 65. I also slowed down on the grades and let the momentum bring the truck up a bit until my speed got down to 55 then slowly increased when it was flat again. My 35 inch tires are like 33.5 now.

That's pretty dang good. What tuning file/timing are you using? That's pretty dang good. What tuning file/timing are you using?

GPS and yes it is corrected to the tire size. I've actually recalibrated it again since my 35's are worn down. I'm actually getting 30% better? I guess my hypermiling is somewhat paying off then lol.

Would that fit on a 17x10 rim? When I looked it up on a tire size comparison website, it said the max would be a 17x9. If I could possibly fit those tires on my rim I might just see an increase in my average fuel economy hopefully. If I can get to 20, I'd be more than happy. I also forget to mention that I have a ton of stuff in my truck and a tool box in the back filled with tools. When I drove over multiple scales they showed that I was at ~9000lbs. I'm sure my tank average is hit by that slightly but I have to leave all that stuff in my truck for the time being. Maybe that could explain the slight drop in average mpg over a course of about 5 years. By the way, how did you manage to get your all time high to 27mpg? Was it mainly hypermiling the truck for that tank?

I originally was going to order the sac injectors but ended up going with VCO's for max fuel mileage. Everything I've researched has seemed to have said that VCO's will get slightly better mileage over sac's. My buddies tell me that I'm a hypermiling bas****

If you don't mind me asking, what cruise timing do you run with your mpg tune when you go 70-80? Maybe I can try experiment with a higher speed to see if my mpg can increase. Thanks!

I just ordered the injectors the other day and asked if they were able to set them to 320. Hopefully they can. I ordered the 7x.010 VCO aftermarket body injectors. Looks like they had them on sale. If for some reason my mpg goes down, I'm gonna flip haha 

That's only if I have a really light foot and baby it though. I've seen it as low as mid 16s-17s if I give it a bit more throttle and try to keep up with traffic at lights or on the freeway. Last trip I had cruise set at 65 and went from Portland to the Wildhorse casino in Pendleton. Got 18.9 mpg that run but I slowed down a little and let the momentum bring the truck up the small grades down to 55 mph then slowly back up to 65. I have also taken off my cold air intake, put the BHAF back on, taped up the fender intake duct, and threw my winter front on to get warmer air to the engine. Supposedly the warmer air should net me better mpgs but would also have a slight power loss. Once I have the available space, I'm getting the stock tires and rims lol.