[aohus]

After doing a Stage 1 MHD tune, I would normally have to fill up once a week. I now have to fill up about once every 5-6 days. And this is from normal driving (to and from work commute).

I'm aware this is expected, but wondering what others are getting.

YMMV. Literally.

[Antetokounmpo]

Depends how much you punch it. If you don't ever go past stock boost (8.5 psi or something) you should theoretically get exactly the same mileage since the afr under light load shouldn't be changed in the tune.

[aohus]

Originally Posted by Heel Toe

Depends how much you punch it. If you don't ever go past stock boost (8.5 psi or something) you should theoretically get exactly the same mileage since the afr under light load shouldn't be changed in the tune.

I will need to buy a boost gauge then. If anyone can chime in for a good boost gauge recommendation I'm all ears. I was looking into the P3 but what else is out there ?

[Antetokounmpo]

Here is a comparison between a stock fuel table and custom fuel table. As you can see the stock fuel table is actually richer (first table). So technically, with exactly the same driving habits (keeping under 8.5psi) you'll achieve better fuel mileage with the aftermarket tune.

Now, since you won't be able to keep out of boost, you'll get worse mileage.

[V8bait]

Originally Posted by Heel Toe

Here is a comparison between a stock fuel table and custom fuel table. As you can see the stock fuel table is actually richer (first table). So technically, with exactly the same driving habits (keeping under 8.5psi) you'll achieve better fuel mileage with the aftermarket tune.

Now, since you won't be able to keep out of boost, you'll get worse mileage.

Interesting fuel table heh.

A stage 1 MHD tune will probably be a bit richer than that table, but between the more aggressive cam timing and more aggressive boost profiles in tunes, your fuel economy will take a slight hit if you decide to touch the loud pedal OP.

[tofu?]

Originally Posted by aohus

I will need to buy a boost gauge then. If anyone can chime in for a good boost gauge recommendation I'm all ears. I was looking into the P3 but what else is out there ?

yes, throw money at useless parts instead of driving like a normal human to preserve mpg

[bradsm87]

When driving the same, my mileage is way better than stock with a custom tune.

[aohus]

Originally Posted by bradsm87

When driving the same, my mileage is way better than stock with a custom tune.

How is that even possible?

Originally Posted by tofu?

yes, throw money at useless parts instead of driving like a normal human to preserve mpg

What makes you think I don't?

[3.1L Z]

I've wondered if the mpg computer changes with a tune??? Or does it just measure throttle and rpm to calculate the estimate mpg...

[mikes4]

Originally Posted by bradsm87

When driving the same, my mileage is way better than stock with a custom tune.

Ditto

[bradsm87]

Originally Posted by 3.1L Z

I've wondered if the mpg computer changes with a tune??? Or does it just measure throttle and rpm to calculate the estimate mpg...

It's quite accurate and based on fuel injected.

[bradsm87]

Originally Posted by aohus

How is that even possible?

No EGR, leaner, more advanced timing. Less thermal loss and less pumping loss.

[Antetokounmpo]

Originally Posted by V8bait

Interesting fuel table heh.

A stage 1 MHD tune will probably be a bit richer than that table, but between the more aggressive cam timing and more aggressive boost profiles in tunes, your fuel economy will take a slight hit if you decide to touch the loud pedal OP.

Yeah agreed. I'd be willing to be under 130 load, the fuel target is OEM with MHD stage 1/2. But I cannot find a mhd stage 1/2 bin...

[Riceball777]

the only reason your gas millage would be worse is because your driving more aggressively or your keeping the car in boost more. Since all stock tunes run on the rich side and all aftermarket tunes run the car leaner if you stay out of boost your gas millage will actually be better with a aftermarket/custom tune over the stock tune.

[Rory]

Im surprised tunes actually run leaner than stock, you'd think the tuners would run a little richer for safety.

[Antetokounmpo]

Originally Posted by Rory

Im surprised tunes actually run leaner than stock, you'd think the tuners would run a little richer for safety.

That's a custom tune, (not made by me) but in low loads, it's really not much leaner, just a few tenths leaner. I'd can almost guarantee you the MHD stage 1/2 bins have the same afr as stock under 130 load.

As for high load, the stock tune runs pig rich for a DI engine. Hence why tuners will lean out the afr in the high loads (which the stock tune will never see)

[Fundguy1]

A couple mpg after a jb4 tune. After switching to my current setup and e85 10 mpg. Course I have a fuel rail and close to 700hp which I use.

[blau iii]

I got the vent boost guage from EAS. it's great but having it right in your face makes your foot go down more and in turn, worse mpg.

[bradsm87]

Originally Posted by Rory

Im surprised tunes actually run leaner than stock, you'd think the tuners would run a little richer for safety.

Low loads don't need to run rich to be sufficiently cooled. The fuel map has different air fuel ratios at all RPM and load. During cruise, going leaner than the already 14.7:1 factory AFR does not significantly increase heat like it does when going from say 12:1 to 14:1. Going leaner than around 15.5:1 actually gets cooler from that point onwards.

Under high load, most tunes run a bit richer than factory at low RPM, about the same as factory in the midrange and a little leaner at very high RPM. This is because the factory tune runs quite lean for emissions purposes at low RPM and runs quite rich at high RPM.

[Speed3Driver]

mine went up 2-3 mpg highway with the jb 4 map 5 i've been driving the same road to work for 5 years at the same 83mph indicated on speedo

[Bumbleb]

Took a huge hit when I switched to full E85 but who cares when those turbos spool.

[08njSTEP]

First couple weeks after installing COBB I was getting 19.9-20.1 with AFR between 14.3-15.1. Now I'm getting 21.7. Same AFR, same driving habits, same route. I see 15-16psi boost.