Discovered setting cruise to 70 MPH instead of 65 results in > 21 MPG for my morning commute

The 3.5-liter 2GR-FKS is quickly becoming my favorite Toyota engine of all time. It just keeps getting better.

At 65 MPH, my RPM is about 2,100, and at 70 it is about 2,300 (I'll double check this next time I'm out). I am starting to wonder if the simulated Atkinson cycle feature only operates at some RPM higher than 2,100 rendering increased efficiency despite turning a higher RPM...

Does anyone know if there are any technical articles floating around regarding our VVT-iW/D-4S that discusses activation points/load limits of the simulated Atkinson cycle?

Also, I mentioned in a recent Marlin Crawler Round-Up picture thread post that last weekend I averaged 20.3 MPG for a 153 mile stretch returning from the Rubicon with a passenger and loaded so heavy that I couldn't see out my back window. Driving solo, no tail wind, no drafting. 20.3 MPH fully loaded on 40s. Love the new Tacoma 6cyl!!

Additional notes:

• RC62F 6spd Manual transmission
  
• 5.29:1 R&P (with ARB air lockers F&R)
  
• Triple Marlin Crawler TacoBox transfer case setup (I have way more gears and drivetrain weight than 99.9% other Tacos; My mileages supports how the added parasitic power loss from the TacoBox is negligible)
  
• Original factory transmission gear oil, ordinary Castrol TacoBox + t/case gear oil, and Redline synthetic diff gear oil (from Marlin Crawler)
  
• I have almost 22K miles on these 40s which have worn down to probably 38-1/2" by now
  
• When I installed the tires back in 2017, their combined weight with beadlock wheels was 133.9 lbs each or 535.6 lbs of rotating mass total which definitely helps maintain inertia for improved constant speed efficiency (my daily commute only has about 2 miles of stop-and-go surface roads)
  
• Speedo calibrated using Hypertech controller P/N 730123 (currently reads about 0.4 MPH too fast; I prefer it to read just barely too fast rather than too slow to help mentally combat speeding tickets; This means that at 70 MPH it is 0.05% too high so that 21.3 is actually 21.2 MPG)
  
• ECU: Factory 2016 firmware updated to 04B13 (about a month ago using @tonered's info here (reply #1828))
• Intake: K&N P/N 63-9039 (more info @ reply #860 here)
  
• Exhaust: Version 2 of my custom high-flow cat-back setup, now using a 2.5" Magnaflow muffler P/N 12586 (more info @ reply #909 here)
  
• Now rock'n a prototype high ground clearance rear Marlin Crawler tube bumper (currently 13 lbs lighter than factory bumper & gained 16" of ground clearance for a vastly improved departure angle)
• My ribs are finally healed enough to go wheel'n again, and I have many PMs I need to respond to & my build thread needs to be updated

Regards,
BigMike

 

Decided to share those pics here I'll post a full trip report with more pics soon. Here is info from the Marlin Crawler forum:

I had a GREAT TIME finally back on the trail. My Tacoma has NEVER performed this great off-road and I can almost take all of my usual lines that I've taken for years in my 1981 Rock Crawler.









#RCLTHD -- MarlinCrawler.com/RCLT-HD

 

A few moar











Bonus images from a member in our group:



This was the morning after the main event, trying to get things loaded up among the remaining rigs



And for an additional efficiency report of the new 3.5-liter, this was a bit before I returned home Sunday. It actually got up to 20.3 MPG over the last 153 mile leg which is just incredible. I was running solo fully loaded with passenger. No tail wind. No drafting. Cruise this time was set to 69 MPH and it does better than 65 MPH. This truck is getting better fuel mileage than my 2.7-liter Hilux. Outright insane how efficient the new 3.5-liter engine + manual transmission is on 40" tires loaded with Round-Up equipment so high I could not see out my rear window.



Here is what the truck looked like loaded for the 240 mile trip back home. I am sure the streamline nature of this configuration aided in my constant-speed fuel efficiency.



Went in from Loon on Thursday and then back out to Loon Sunday. The Taco has done the Rubicon 8 times now without any body damage

 

WOW!!
20mpg on 40’s and fully loaded!! Sounds impossible.
Congrats on doing something very RIGHT! You have a great rig!
You are my Hero!
I don’t think I could get 20mpg if I was being towed. Lol

 

right on man

 

In closing, the reason for all the gear is that these pics are from our annual Marlin Crawler event (next event will be Sept 2020, details here) so we bring in hundreds of raffle prizes and enough food and supplies for over 350 people which is a lot of work for us and our trail rigs.

For reference, this is how The Crawler Truck gets loaded sometimes... This world famous 1980 Toyota has been continuously wheeled for 36 years, 25 of which with a Triple Marlin Crawler transfer case setup that has yet to fail and has been highway driven and wheeled in the Pacific Coastal Range, Sierra Nevadas, Red Rock Canyon lands, Colorado Plateau, Rockies, Hot Springs of Arkansas, and the Appalachians...

The Crawler Truck is powered with a 1st gen Tacoma 2.7-liter 3RZ-FE and makes about 18 MPG on the highway with 37" IROK tires.



So not only does an event like this prove how high quality parts can take you to a difficult trail, run it without any damage, and drive back home safely, but it also serves as a great load and stress-test on the engine which was great in checking my fuel mileage with the Tacoma

Our 18th annual event was our 2nd largest to date and was a LOT of fun. Our Facebook header image says it all, and to date the event has raised & donated $140,682 to the Rubicon trail



Regards,
BigMike

 

Wow that’s sweet! That’s crazy.

In before all the 4.0 crowd and turd gen haters arrive.

 

them bed nets work real good

 

haha Thanks man. The 4.0 is a great engine also, but it's a bummer Toyota never offered the dual VVT-i 4Runner/FJ C engine for the 2nd gen Tacoma. There could have been an improvement. I have a few 4.0 friends on 40s with autos that average 17 to 18 MPG on the highway, but I have yet to meet a 4.0 on 40s that can manage over 20 MPG fully loaded.

 

Here is the one I'm using. I've used it since 2017 and it is holding up extremely well:

$35 TacoNets Toyota Tacoma Long Bed Cargo Net - Patent Pending Design - Fits 2005-2023 - Heavy Duty 8mm Premium Bungee 3'x5' Cargo Netting - Designed in USA

https://www.amazon.com/gp/product/B013HRKDW2/ It is compatible with 2005+ Tacoma bed rails. As for my bed, I have shortened it 6-inches (bobbed, more info spanning 3 pages from reply #252 here) so the net can stretch up quite a bit and still connect to all points which is nice.

 

dam that thing is serious hooks right into the OE bed rails