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Mon Jul 04, 2022 4:58 pm

Our new/old 1982 Westy, freshly tuned up at a VW-only garage, maiden voyage, loaded for camping, about 2/3rds Interstate (at 60), 1/3rd two-lane back roads (at ~45), 206 miles on 11.5 gallons, for 17.9 mpg.

The trip was largely uneventful, except a dead battery when we were ready to leave. Looks like we have to debug the house/starting battery wiring…

Thu Aug 18, 2022 9:11 pm

Tank-to-tank on our recent trip from western WA to eastern MI:

Bellingham, WA begin
Omak, WA: 19.83
Newport, WA: 18.3
Kalispell, MT: 18.83
Browning, WY: 18.4
Great Falls, MT: 18.87
Livingston, MT: 17.25
West Yellowstone, MT: 15.38
Cody, WY: 15.52
Gillette, WY: 17.9
Faith, SD: 17.94 (10% ethanol)
Aberdeen, SD: 17.28 (no ethanol)
Richmond, MN: 16.62 (91 octane, no ethanol)
Cameron, WI: 19.38 (91 octane, no ethanol)
Norway, WI: 18.66 (10% ethanol)
Nahma, MI: ?? loud knocking, called tow truck :-(

Thu Aug 18, 2022 9:27 pm

Filled up with 87 ocatane and did a winding, sea level to 2800ft to sea level (3x each way) drive last weekend and clocked 16.9mpg. Curious to see what it will be if I'm ever driving on a flat freeway at 55mph.

Fri Aug 19, 2022 4:04 pm

On our 800 mile trip to Northern CA/OR coast in July we averaged 19 mpg. Stock 2.1L WBX.

Sun Apr 23, 2023 5:17 pm

At recent trans rebuild I had the .77:1 4th gear replaced with factory ratio .85.
I expected about 300 higher RPMs at 65 MPH. (Was about 3200 RPM.)
Now seeing about 3800 RPM at 65-70 MPH.*
Maybe too high?
Not sure how much this will affect gas mileage.

*About what a 1:1 would yield.

Sun Apr 23, 2023 10:14 pm

BCE56 wrote: At recent trans rebuild I had the .77:1 4th gear replaced with factory ratio .85.
I expected about 300 higher RPMs at 65 MPH. (Was about 3200 RPM.)
Now seeing about 3800 RPM at 65-70 MPH.*
Maybe too high?
Not sure how much this will affect gas mileage.

*About what a 1:1 would yield.

Calcs from my transmission/tire ratio spreadsheet suggest a 300 rpm difference at 65 mph changing from a .77 to .85 4th gear so you'd be going the same 65 mph with a 300 rpm increase changing from .77 to .85, assuming a 4.86 R&P and OE 185/80 R14 tires (rows 2 and 4 below). So we're aligned on a 300 rpm difference at 65 mph for these two 4th gears.

At 3,800 rpm the spreadsheet says you'd be going 70.6 mph.

You're not seeing 3,800 rpm at 65-70 mph (unless your clutch is slipping); you're more likely seeing 3,500 - 3,800 rpm at 65 - 70 mph and 3,800 rpm at 70 mph.

As to whether to not this is running your Subie to fast I'd guess the answer is no. My guess is that 90% of Subie conversions are running stock 4th gear and R&P ratios (.85 and 4.86) and they're doing fine. If you're concerned about the rpms being too high then two easy options are to slow down rpms by installing larger diameter tires (something that many, most(?), Subie owners have done).

Mon Apr 24, 2023 1:57 am

Tire sizes are a bit like shoe sizes. There is significant variation in fit even when the "size" is the "same".
For gearing purposes the rev/mile spec is what counts.
Stock Vangon 185R14 run about 810 rev/mile.
So called calculator programs often just guess at this spec from the "size" and get it mostly wrong.
So their numbers based on wrong guesses are likewise off.
For many tires you can look up their published rev/mile spec and some calculator programs will let you use it rather than their guessed at number.

Mark

Mon Apr 24, 2023 10:26 am

crazyvwvanman wrote: Tire sizes are a bit like shoe sizes. There is significant variation in fit even when the "size" is the "same".
Mark

Agreed. Back when I was obsessing over gear/R&P/tire changes I rolled the van 1 full rotation of the tires to measure actual distance travelled to enter into the spreadsheet to calculate RPM and MPH.

As to BCE56's question regarding impact to mpg with the motor running ~300ish RPM higher at 65 mph, I'm guessing the impact will be minimal (less than the impact of driving at 70 or 75 mph v 65). It'd be interesting if other Subie. drivers have data on this.

Mon Apr 24, 2023 11:24 am

crazyvwvanman wrote: Tire sizes are a bit like shoe sizes. There is significant variation in fit even when the "size" is the "same".
For gearing purposes the rev/mile spec is what counts.
Stock Vangon 185R14 run about 810 rev/mile.
So called calculator programs often just guess at this spec from the "size" and get it mostly wrong.
So their numbers based on wrong guesses are likewise off.
For many tires you can look up their published rev/mile spec and some calculator programs will let you use it rather than their guessed at number.

Mark
Good info Mark! My 215/65-16 is listed as 27" by the manufacturer, but using their published Revs/Mile for this same tire - it is 27.25" - a bit taller.
I'll try a roll out someday and see how it compares.

Mon Apr 24, 2023 11:49 am

jimf909 wrote: It'd be interesting if other Subie. drivers have data on this.

the 2.5 Subaru's in stock form cruise about 32-3400 rpm's at 70-72 mph (5 speed, automatics are a tick lower due to the lock up converter)

I put taller tires on my automatic seeing I have a 1 gear penalty (or 2, depending how you look at it)

My cruising RPM's are about 35-3600 rpm's @ 74 mph. That said, no matter how I drive it, it seems to get about 22-24 mpg's which honestly, is in line for the year/model of the donor car

one thing people tend to overlook with gearing is they have it in their head "i wanna turn 2k rpm's at 70mph" because they think this is good.

it's not

you have to match the gearing to the engine's torque range, period. if not, you'll have a gas guzzling gutless pig.

Mon Apr 24, 2023 1:31 pm

Thanks for replies.
Spreadsheet above agrees with what I'm seeing.

My Syncro:
215/75 X 15 BFG AT/TA (New set of 5 KO 2 coming tomorrow.)
Stock R & P front and rear
Factory tach. agrees w/ diagnostic computer- w/in 100 RPM at 4000.
Speedo/odometer (driven off front diff) error about 7% low.
I don't notice any clutch slippage.

Recent work includes A/C overhaul, CVJ replacement, trans & shift linkage rebuilt in preparation for road trip to CO this summer. Long, flat highways, multiple mountain passes and some dirt roads at destination.
I wonder how the 4th gear change will affect performance, engine temps and gas mileage.

Syncrofest (if I can make it) will be a good shakedown.

P.S. Why no chatter about Syncrofest?

Mon Apr 24, 2023 2:08 pm

Year - 1984
Model - Tin-top
Engine - 1.9 ALH TDI
Trans - 4-speed DK with .77 4th gear
Mods - other than above, none
Tires - 215/75/15 Uniroyals

32-34 MPG

25-26 Pulling a popup camper

Mon Apr 24, 2023 6:30 pm

Mckinleyvillian wrote: Filled up with 87 ocatane and did a winding, sea level to 2800ft to sea level (3x each way) drive last weekend and clocked 16.9mpg. Curious to see what it will be if I'm ever driving on a flat freeway at 55mph.

gonna get back in here to note that with refurbished injectors, cleaned up vacuum leaks, and some more general maintenance fuel economy has jumped to 18 stop and go short trip driving around town. I'm looking forward to seeing what it's going to be like on a long freeway drive.

Mon Apr 24, 2023 6:53 pm

1987
Syncro Doka
DJ 2.1L
AAN 5-speed (4.86 final)
GoWesty/Magnaflow full exhaust system with catalytic converter
225/75R16 Cooper Discoverer AT3 4S tires (29.1”)
Driven in RWD 99% of time

Averaging 14-15MPG if I stay under 70MPH

Fri Sep 29, 2023 2:49 pm

Recently completed 6500 mile trip in our Westy with Subaru 2.5, 215/75/15 KO2s. Drove 65 mph most of the time, at 3600 rpm, and got 19 mpg over the entire trip.
Don’t know why my rpm’s are so high at that speed, but that is a topic for another thread.l

Fri Sep 29, 2023 2:59 pm

My 90 2.1 Automatic is currently in the midst of a rebirth from a daily work Van to a travel Camper.

I’ve removed well over 1000 lbs of tools and supplies.

Fully loaded (5,000 lbs + ) as a work Van I got a constant 14-15 mpg.

I wonder with a transmission Refresh and shedding some weight if it will be much better?

Time will tell……

Fri Sep 29, 2023 4:43 pm

Chilepines wrote: Recently completed 6500 mile trip in our Westy with Subaru 2.5, 215/75/15 KO2s. Drove 65 mph most of the time, at 3600 rpm, and got 19 mpg over the entire trip.
Don’t know why my rpm’s are so high at that speed, but that is a topic for another thread.l

That MPG vs. RPM seems about right IF your tach and odometer are correct.
And if your 4th gear ratio is stock.

My Syncro- EJ22, 215/75/15 KO2s, .85:1 4th got 16.1 MPG last tank (E 10 regular), all city driving.
I expect significantly better mileage on longer highway trips at speeds and RPMs similar to yours.

Fri Sep 29, 2023 9:04 pm

Chilepines wrote: Recently completed 6500 mile trip in our Westy with Subaru 2.5, 215/75/15 KO2s. Drove 65 mph most of the time, at 3600 rpm, and got 19 mpg over the entire trip.
Don’t know why my rpm’s are so high at that speed, but that is a topic for another thread.l

Either your Speedometer or Tachometer is wrong.

According to my interactive Excel Spreadsheet, with stock gearing (0.85 4th gear and 4.83 or 4.86 R&P) and 215/75/15 tires, at 3600 RPMs your speed should be 72 MPH.

My interactive Excel Spreadsheet has been extremely close to the real world numbers I see with my TDI Vanagon. I calibrated my Speedometer with a Dakota Digital Interface and GPS. And, the odometer is about 99.999 per cent accurate.

Fri Sep 29, 2023 10:09 pm

https://www.fuelly.com/car/volkswagen/vanagon

Sat Sep 30, 2023 6:51 am

With my ea288 conversion, i got about 25-28 (diesel) fully loaded on my trip from Yosemite to Nashville