This is Why I Love My Manual Tranny

Congrats. Don't hang around here too long or that stream will turn into a river.

 

I'll stick to my 14.8mpg...

 

Too late…

 

Well then, may I introduce you to the 2Lo Mod (2LM) and Accumulator Delete Mod (ADM)?


Top it off with a tune and you're set. LoL!

 

I understand it's not THAT high...but definitely higher than it needs to be. Sure, higher speeds = more wind resistance but an A/T has that same resistance. There's a reason they get 1-2MPG better on average at highway speeds. A faster spinning motor, regardless of how you put it, will burn more fuel so long as you're not LUGGING it, and this V6 seems to have plenty of power to chug along at lower RPMs.

 

Sorry, it really doesn't work that way. The fact remains, automatic transmissions have more parasitic drag as well as pumping losses compared to manual transmissions. As for the lower the RPM the better the mileage, also largely a myth.

 

Alright then, go ahead and drive around in first.

 

Or more realistic, go spend some time on the highway in 4th and compare to how your mileage compares in 6th.

It does work that way - to a point. As long as your vehicle sits in a "good" part of its power band. Hence some final drives will be lower/higher to put the engine in the sweet spot. Both final drives in 6th work for our trucks - the A/T works better at higher speeds.

And A/Ts nowadays have been getting quite a lot better at getting better mileage. Of course you have parasitic draw through the T/C and fluid dynamics...they're still not perfect.

 

You missed the point entirely. The context of my comments was whether a top gear/final in a manual transmission resulted in a RPM a few hundred revs higher than an otherwise identical vehicle with an automatic transmission. The fact is, modern automatics are heavily tuned to achieve high EPA MPG results, which do result in better ratings than an otherwise identical manual transmission equipped vehicle. In virtually every case I know of, regardless of whether it is a Toyota, a Honda, a VW, a BMW..., the cars with automatics A) have taller overall gearing, B) have EPA mileage ratings as good as or better than the manual transmission vehicle, and C) will not be able to match the car with a manual in the real world.

 

That is the answer.

 

Very true. It really wasn't to say that bringing the RPMs down would equal MPGs from the auto. I just really do think that the final drive in our M/Ts could stand to be a bit lower to get a few tenths of MPGs at speed.

 

I'd bet you dollars to donuts your premise wouldn't work out as you think. Automaker spend HUGE money trying to achieve the highest MPGs possible, and if it was a simple matter of throwing a slightly taller overdrive in a manual gearbox, they'd do it. FWIW, I'm not talking out of my backside either, I'm a forensic engineer and have worked for three of the world's automakers, one from the U.S., one from Germany, and one from Sweden and have spent a LOT of time in the lab.

 

Thanks - gave them a call and put in a future allocation for a potential Lunar build. Army Green just ins't my ideal color...

 

I bet you're right. But I feel like you and I both know that the world is run by a lot of bad engineers (or bad engineering practices put in place for cost savings - I'm a software engineer and can tell you the world is run by very bad software). An extreme example of this would be the Boeing 737 MAX. Things happen for cost savings. Maybe this version of RC transmission couldn't have a taller gear for X/Y/Z reason so instead of redesigning a COMPLETELY new trans they just stuck in what would work and said "screw it."

Also if the few hundred RPMs don't make a difference, then well I might as well not use 6th at all. 5th and 6th are really that close.

Anyway - really just talking through my frustrations of driving this thing on the highway. Thing absolutely screams at speed and it's probably the only thing I don't like about this truck - it sounds the same as my '04 Jeep Liberty did at 85-90MPH while I'm only doing 75.

 

As I've suggested elsewhere, purchasing my new MT in Denver then driving it back to Texas was one of the peak experiences of my life. And would have remained so even had I not discovered later that the gas mileage indicator was set to register miles per IMPERIAL gallon (just a thought....)

 

Uh you sure about that? An imperial gallon is about .75 liters (~18%) more than a US gallon which would make the calculation way way off.

 

Yes. The numbers I was getting were in fact WAY to good to be true.

Since then, I've managed to make 21 mpg (American) on a couple of trips by keeping the speed around a smooth 65 mph.

 

Last fill up two days ago was 17.8 gallons of Shell 93 after 385 miles for an average of 21.6mpg and cost about $80. It's interesting to me that half the people around here go WOT to pass me and then slam on the brakes at the red light coming up in a few hundred feet. So this leads me to ask,

Does anything think this gas price increase will have an impact on people's driving style, or nah?

 

I absolutely believe that a deeper 6th would result in slightly improved mpg at highway speeds.

I don't think mpg was the primary factor in deciding the 6th gear ratio. It seems to be a widespread philosophy across manufacturers producing manuals for America to err on the higher side for a top gear final drive ratio.

This is me speculating, but I think it's done because they don't believe drivers want to downshift often on interstate inclines. Every manual I've owned has been able to easily maintain top gear on non-mountain interstates. Maybe they also want to reduce the cruise control lugging and associated canceling of the cruise scenario. You know a car reviewer is going to complain if a vehicle can't maintain cruise up a minor hill.

It also seems manuals are designed with the lowest common denominator in mind. Hence the existence of the accumulator.

 

I don't mean to nitpick here, but no you can't.

You can only lock out higher gears. It's not possible to force it to stay in a gear or go higher. If you're going along at say 40 mph in S4 and put the accelerator to the floor, it's going to downshift and there's no preventing that (stock).

One of the great joys of a manual is being able to apply full throttle to whatever gear you want and having a direct connection (no TC slip).