7MT owners, do you use 5 or 6?

[Amcole1984]

I went on a road trip and I am finding that once I hit top speed (I drive the speed limit except for passing situations), shifting into 5 causes the turbo to run constantly. Staying in 4 keeps it at 0.0, and the rpms at around 3.1-3.7. Is one condition better for the engine and gas mileage than the other?

Rarely do I get to speeds where I could use 5th or 6th. Most of my driving is during rush hour on I35 to and from work. So I mainly use 2nd gear. Sometimes I get to 3rd, only for the person in front of me to slam on their brakes and it's back to 2nd gear....

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[Brian_B]

When can I tell the speed or rpm when the turbos are kicking in?

To answer your questions

On the Mileage graph — the outer number is instantaneous — if you mash on the gas it will drop immediately toward 0, if you coast downhill it will peg at 30. If you can hit a flat straight on cruise control it will settle at some middle ground. It reacts instantly

The inner number is your average - over the last 500 miles or so? I don’t know how long, but you will really only see it change slowly over time.

So if you mind the instantaneous, the long term will eventually catch up.

For the turbo - you can hear it whistle when it’s up over about 5 psi pretty audibly. There is also a cluster gauge setting that lets you see if it you scroll through - one just with Boost, and another that has Boost, oil temp, trans temp and battery voltage all together.

Turbo boost is not tied directly to engine rpm - it’s more closely tied to the amount of power the engine is making (which means more air, which means more exhaust, which spins the turbo to push more air). I run plenty of engines at work that only operate at a fixed RPM and they have turbos that don’t boost all the time - just as their power goes up.

Most of the time in normal flat driving that will happen to be on upshifts if you accelerate hard - that’s where most people notice it, but it’s possible to accelerate and up shift without hitting boost at all. It’s also possible to get the engine to boost at low RPMs - like going up a hill in too high of a gear.

There is also a wastegate - that will open to dump charge pressure (drop the boost). That is there for a few reasons - it helps keep you from overboosting and blowing up the engine, it’s part of torque management (no boost in granny or 1st to keep you from burning rubber off the line), it lets the boost die off and the engine throttle down faster (kind of the opposite of turbo lag - like when you shift to neutral the engine rpm doesn’t scream if there is suddenly no load), and it allows Ford to install a larger turbo than the engine would otherwise be able to use.

 

[Golfsnob]

Florida flatlander. Highest elevation I encounter is an overpass. Mix of town and highway and I use 6th when running 70-72 at 2,000 rpm on I95. When you can actually drive that fast on 95 since not seems to be backed up multiple times daily. Gotta be all those folks headed to Buccee's.

 

[kodiakisland]

Can you please explain fps for a newbie?

Pretty sure they meant rpm?

lol, yeah. Was watching Garand Thumb and typing at the same time. RPM. My bad.

 

[AZ_Liberty]

When can I tell the speed or rpm when the turbos are kicking in?

Switch to the boost gauge.

 

[Bmadda]

While my build has gone a bit over the top w/portals, I had given up on 5th and 6th when it was on 37s, and I tried 5th again w/the portal reduction and it still is better to just leave it in 4th, both for mileage and drive ability. Has the power to cruise in 5th, but mileage sucks and turbo is pushing too hard for long distance

 

[Sparkherd]

Rarely do I get to speeds where I could use 5th or 6th. Most of my driving is during rush hour on I35 to and from work. So I mainly use 2nd gear. Sometimes I get to 3rd, only for the person in front of me to slam on their brakes and it's back to 2nd gear....

I-35; The Bloodbath Known As...

 

[Sparkherd]

lol, yeah. Was watching Garand Thumb and typing at the same time. RPM. My bad.

I've got Garand Thumb...'Merca Baybee!!!

 

[Amcole1984]

I-35; The Bloodbath Known As...

Exactly!

 

[GoHack]

6th when I'm on the interstate.
Locally, 4th or 5th.

 

[l88m22vette]

3rd around town, 4th for bigger roads, 5th for interstates, 6th when I want to try it for a little while before I got back to 5th.

My 33" BL seems to be magic in 5th gear at 72mph/~2700rpm, I eeked out 21.6mpg on a trip down IL through MO last year. I have the mod bumper with RokBlokz, and am otherwise stock on 93oct; not aerodynamic, but I like the octane flexibility. I have noticed better mileage with 37-38psi in the K02s, but tend to stick to 35-36 to account for temp variation.

I have an aFe intake and hi-flow muffler waiting in boxes, and would like the FP tune and probably colder plugs. I think those would make a big mileage difference, as would an eventual FMIC upgrade. You wanna improve MPGs? Let the engine breathe as easily as possible, its more efficient and more powerful. Hmm, I wonder if 6th would actually get used then?

 

[NirWheels]

Rarely use the 6th, only when over 75 , flat or downhill and no traffic. It doesn’t have enough torque to deal with a speed change and dealing with the high wind resistance.

 

[Sail]

i was in 6th…

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