[Jeffman]

Originally Posted by Litos

if you're driving ther car normal, you shouldn't see a decrease in MPG.

i was getting 26mpg stock, then went to JB4 and still got 26mpg.

now i'm Cobb Stage 1 and will admit i get @ 23-24mpg ONLY BECAUSE the boost comes on a bit quicker and i like feeling it.

when the feeling of the "new tune" goes away, i'll be back at 26mpg.

on the highway nothing changed from stock, to JB4 to Cobb.

The dynos I've seen in other threads shows the air-fuel ratio (AFR) dropping quickly down from about 15 or 16 to 12 at RPM over 2900 when the boost seems to be maximized, whereas stock keeps AFR around 15 or 16. I think the AFR of just over 12 is the major reason for the much lower mileage with the Cobb when under high boost - about 25% more fuel in the mixture than air entering the cylinders compared to stock. So above 2900 RPM it would seem that fuel economy could easily drop by 25%, say from 28 MPG down to 21 MPG. I think in 6th gear 2900 RPM corresponds to about 90 MPH, so highway mileage should be okay under cruising conditions....

But we all know this. Best fuel economy is achieved with the lowest RPM in the highest gear. Most if not all tuners are looking for maximum torque and power. Wouldn't it be useful to see a tune that actually improves mileage, i.e., keep the AFR higher than stock? Not sure how to extract more chemical energy out of less gas, however. This is probably what the BMW engineers are constantly working on, IMHO.

[Litos]

Originally Posted by JHR

The dynos I've seen in other threads shows the air-fuel ratio (AFR) dropping quickly down from about 15 or 16 to 12 at RPM over 2900 when the boost seems to be maximized, whereas stock keeps AFR around 15 or 16. I think the AFR of just over 12 is the major reason for the much lower mileage with the Cobb when under high boost - about 25% more fuel in the mixture than air entering the cylinders compared to stock. So above 2900 RPM it would seem that fuel economy could easily drop by 25%, say from 28 MPG down to 21 MPG. I think in 6th gear 2900 RPM corresponds to about 90 MPH, so highway mileage should be okay under cruising conditions....

But we all know this. Best fuel economy is achieved with the lowest RPM in the highest gear. Most if not all tuners are looking for maximum torque and power. Wouldn't it be useful to see a tune that actually improves mileage, i.e., keep the AFR higher than stock? Not sure how to extract more chemical energy out of less gas, however. This is probably what the BMW engineers are constantly working on, IMHO.

great post - now that i have driven @ 2000 miles i honestly believe the Cobb is getting less gas mileage.

i used to get 26-27mpg with JB4 - now i see 24.

not "drastic", but less is less.

it doesn't bother me because i don't like seeing high 13 A/F's at WOT like i did with the JB4.

[Nuke335i]

Great comparison chart! Please update with more Cobb info!

[Vegas_Sirk]

Originally Posted by Nuke335i

Great comparison chart! Please update with more Cobb info!

+1

[Jeffman]

+1

[AltecBX]

Thanks guys. There has been some new features from every camp here.
I'm waiting on Cobb to get back to me. Once I hear from them I'll be revising the chart.

[eaglesfan83]

Great chart. I am deciding on whats the best route to go as well. Very helpful. Cant wait to see the new chart! Thanks for putting it together.

[TwinTuning]

Thanks,very helpful.

[Chalo1]

Thanks for taking the time in creating such a great comparison. It really helps!!

[hsantiago335]

great info 4 someone considering which tune to get thanks

[wilkoal]

Originally Posted by AltecBX

Thanks guys. There has been some new features from every camp here.
I'm waiting on Cobb to get back to me. Once I hear from them I'll be revising the chart.

AltecBX when updating you should also consider inserting a new column for Evolve specs!!

[Kayani_1]

Any info provided by Cobb...would love to see a comparison of them vs others. Specially JB4 vs them. Since I run JB4 right now and would like to compare cobb features and gains against there.

Please, post the info soon.

Originally Posted by AltecBX

Thanks guys. There has been some new features from every camp here.
I'm waiting on Cobb to get back to me. Once I hear from them I'll be revising the chart.

[JamesM3M5]

This helps incredibly. Can't thank you enough. I've been a BMW nut/shadetree mechanic turned shop owner, and the new technologies were starting to pass me by. Finally got my own 335i, and installed a Procede just a couple weeks later. I am sold on the capabilities of the Procede over even custom tuning. After working with some professional tuners at all levels, I like what I read and hear from Shiv.

Not sure why some do it, but 12.5 lambda at low revs isn't necessary on this engine. No risk of detonation, haven't seen logs of anyone with timing pulled from the knock sensors, either. Warm, fuzzy feeling is fine, but don't do something the old way just because it makes you feel better.

[M5stalker]

JB4 FTW

[duvinclunk]

Glad I found this.

[Wedge1967]

Nice work.

[AltecBX]

Looking to take some time this month to update the chart guys. I'll keep you posted; Every team has come up with more since I last updated the current chart.

[x26]

Great Job and Thanks!!

[BEAR-AvHistory]

JB4 93 octane map2 all else is factory stock.

[ynoty3k]

Those numbers look solid. The comparison chart is great, but it left out one thing; The personal service Terry from BugerMotorSports brings to the table when you buy a JB4!

[dori604]

great work - helps new owners make sound decisions - thank you

[Vegas_Sirk]

Yea I would really love to see Cobb's stuff in there as its pretty much empty. I really want to compare them and the JB