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Noahfreak · 04-09-2014, 07:37 PM

Hi Everyone,

I just wanted to give a thread update for the mods I've been working on. I recently made a cross-country trip so I did a bunch of mods to prepare for it:

-Reduced tire size from 31" tires (~265/75r15) to 235/75r15's. They're Wranglers, so not the best, but much better than the off road 265s. This lowered the ride height some too.
-Switched from 3.55:1 to 3.08:1 rear gear ratio, filled with synthetic oil, and put a brand new driveshaft carrier bearing on.
-Installed a vacuum gauge to monitor my throttle position, which helps a lot! This engine is super quiet, so I have no idea what the engine is doing without looking at the tach (or now the vacuum gauge).
-Installed a new fan clutch to make sure that's working properly.

On the dead head portion of the 5300 mile round trip, I averaged about 14.5 mpg for the first few fill ups. While I was running through mountains for much of this, this seemed a little low to me considering I was getting that around town the week before I left. Since it was 75 degrees when I left San Diego, and the temperature dropped as soon as I got into Arizona, I finally figured out by the time the temp was in the single digits (polar vortex) that I should recheck the psi on the tires, which were set at 35 when I left. They had dropped over 10 psi by the time I was in Oklahoma! I pumped them back up and immediately saw a huge jump in mpg. The last day of the trip I averaged 18.7 mpg on the final leg! That puts me really close to my 20 mpg target for highway mileage.
Another interesting thing of note was that the amount of vacuum that the engine would pull at elevation was significantly lower than at sea level. It dropped to the mid-teens at the highest elevations, while it sits at 23 inches of mercury at sea level.
On the way back, I had about an extra 4500 lbs on the truck, including an enclosed trailer which really screwed up my aerodynamics (no cap on the truck), so my average dropped back down to 12 mpg for the rest of the trip. I had hoped for a little better than that, but I think that's pretty decent since it's better than the unladen mpg I got when I first purchased the truck, and the majority of my trip was in sub-freezing temps.
Since I got back in February, I've made a few more mods:

-The new engine has about 10k on it finally, so I just switched to full synthetic 10W-30.
-Installed a K&N 57-2503 FIPK intake kit. I would have made my own, but, California.

People have borrowed it from me several times since then so I haven't had the chance to monitor mileage, but I'll let everyone know if I hit the 20 mpg Holy Grail I'm shooting for on the highway.

Some planned mods:

-Exhaust. I'm planning on a 2.5" home-built setup that will start right after the second cat and will exit in front of the passenger rear tire.
-Thinking about how my aero mods are going to go. I don't want these to draw any negative attention from the cops, so I'll have to take some care to make sure they're aesthetically decent.
-I've also heard that these things respond well to port and polish jobs on the head intake and exhaust bowls. I have an extra head in storage right now, so I may go to town on that as well with a Dremel tool.
-The trip I made to Buffalo was mostly to pick up a Bridgeport J-Head Mill, so now that I have the capability to machine the head, I might also install an adjustable valve train on it with roller rockers and screw-in rocker studs. I don't like that I can't set the valve lash on this engine without buying different length push rods, and the roller rockers should help reduce valve-train mechanical losses. We'll see when I get to that.

Sorry for the long post. A lot has happened since the last time I updated. Let me know what you guys think!

04-09-2014, 07:37 PM	#20 (permalink)
Noahfreak EcoModding Lurker Join Date: Jul 2013 Location: San Diego Posts: 20 Goldy II - '94 Saturn SC2 Last 3: 26.24 mpg (US) The Beast - '88 Ford F150 XLT Lariat, Supercab, Long Bed 90 day: 13.61 mpg (US) Domo - '89 Honda Civic Wagovan 90 day: 30.49 mpg (US) Thanks: 2 Thanked 2 Times in 2 Posts	Update on Mods Hi Everyone, I just wanted to give a thread update for the mods I've been working on. I recently made a cross-country trip so I did a bunch of mods to prepare for it: -Reduced tire size from 31" tires (~265/75r15) to 235/75r15's. They're Wranglers, so not the best, but much better than the off road 265s. This lowered the ride height some too. -Switched from 3.55:1 to 3.08:1 rear gear ratio, filled with synthetic oil, and put a brand new driveshaft carrier bearing on. -Installed a vacuum gauge to monitor my throttle position, which helps a lot! This engine is super quiet, so I have no idea what the engine is doing without looking at the tach (or now the vacuum gauge). -Installed a new fan clutch to make sure that's working properly. On the dead head portion of the 5300 mile round trip, I averaged about 14.5 mpg for the first few fill ups. While I was running through mountains for much of this, this seemed a little low to me considering I was getting that around town the week before I left. Since it was 75 degrees when I left San Diego, and the temperature dropped as soon as I got into Arizona, I finally figured out by the time the temp was in the single digits (polar vortex) that I should recheck the psi on the tires, which were set at 35 when I left. They had dropped over 10 psi by the time I was in Oklahoma! I pumped them back up and immediately saw a huge jump in mpg. The last day of the trip I averaged 18.7 mpg on the final leg! That puts me really close to my 20 mpg target for highway mileage. Another interesting thing of note was that the amount of vacuum that the engine would pull at elevation was significantly lower than at sea level. It dropped to the mid-teens at the highest elevations, while it sits at 23 inches of mercury at sea level. On the way back, I had about an extra 4500 lbs on the truck, including an enclosed trailer which really screwed up my aerodynamics (no cap on the truck), so my average dropped back down to 12 mpg for the rest of the trip. I had hoped for a little better than that, but I think that's pretty decent since it's better than the unladen mpg I got when I first purchased the truck, and the majority of my trip was in sub-freezing temps. Since I got back in February, I've made a few more mods: -The new engine has about 10k on it finally, so I just switched to full synthetic 10W-30. -Installed a K&N 57-2503 FIPK intake kit. I would have made my own, but, California. People have borrowed it from me several times since then so I haven't had the chance to monitor mileage, but I'll let everyone know if I hit the 20 mpg Holy Grail I'm shooting for on the highway. Some planned mods: -Exhaust. I'm planning on a 2.5" home-built setup that will start right after the second cat and will exit in front of the passenger rear tire. -Thinking about how my aero mods are going to go. I don't want these to draw any negative attention from the cops, so I'll have to take some care to make sure they're aesthetically decent. -I've also heard that these things respond well to port and polish jobs on the head intake and exhaust bowls. I have an extra head in storage right now, so I may go to town on that as well with a Dremel tool. -The trip I made to Buffalo was mostly to pick up a Bridgeport J-Head Mill, so now that I have the capability to machine the head, I might also install an adjustable valve train on it with roller rockers and screw-in rocker studs. I don't like that I can't set the valve lash on this engine without buying different length push rods, and the roller rockers should help reduce valve-train mechanical losses. We'll see when I get to that. Sorry for the long post. A lot has happened since the last time I updated. Let me know what you guys think!