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M2 Technical Topics > N55 Engine / Drivetrain / Exhaust / Bolt-ons / Tuning > first gear is a dog

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      04-16-2019, 05:31 PM   #1
Rex Mason
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first gear is a dog

Hi all,

I am currently running bootmod stg 2 on 93 octane with chargepipe, downpipe, intercooler. I had a boost leak when my dp bung decided to make an escape. I fixed that but i still feel like first gear is a dog.

I have a log at the link below. Anyone see anything off?

http://www.bootmod3.net/log?id=5ca8f354c090c636d966886b

I can do a dedicated pull if needed. It looks like i am hitting my targets but a second set of eyes would be great.

Thx!

J
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      04-16-2019, 08:06 PM   #2
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Keep in mind that turbos are load dependent and 1st and 2nd gears have a lot of torque multiplication from the gearing, thus, those gears do not generate much load on the turbo so they do not generate near as much boost as 3rd and beyond.

1st gear will likely not generate much boost because:

1) The torque multiplication of 1st gear
2) Shortness of 1st gear vs time in gear vs time needed to load the turbo and build boost

For example, my stock M235 6MT with just a catted DP and no tune, generates around 6-7psi in 1st, 7-8 psi in 2nd, 9-11 psi in 3rd and beyond, depending on density altitude conditions.
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      04-17-2019, 12:11 AM   #3
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Quote:
Originally Posted by XutvJet View Post
Keep in mind that turbos are load dependent and 1st and 2nd gears have a lot of torque multiplication from the gearing, thus, those gears do not generate much load on the turbo so they do not generate near as much boost as 3rd and beyond.

1st gear will likely not generate much boost because:

1) The torque multiplication of 1st gear
2) Shortness of 1st gear vs time in gear vs time needed to load the turbo and build boost

For example, my stock M235 6MT with just a catted DP and no tune, generates around 6-7psi in 1st, 7-8 psi in 2nd, 9-11 psi in 3rd and beyond, depending on density altitude conditions.
+1

first and second gear are too short to reach max boost, thats why datalogs are always done on higher gears
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      04-17-2019, 08:11 AM   #4
Rex Mason
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Quote:
Originally Posted by mike@x-ph.com View Post
+1

first and second gear are too short to reach max boost, thats why datalogs are always done on higher gears
Cool, Iíll pull a 3rd gear log later this week. Doing some additional research, I think getting my mdm changed to euro mode might help with the power cuts I am feeling
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      04-17-2019, 08:22 AM   #5
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Quote:
Originally Posted by Rex Mason View Post
Quote:
Originally Posted by mike@x-ph.com View Post
+1

first and second gear are too short to reach max boost, thats why datalogs are always done on higher gears
Cool, I’ll pull a 3rd gear log later this week. Doing some additional research, I think getting my mdm changed to euro mode might help with the power cuts I am feeling
Quote:
Originally Posted by Rex Mason View Post
Quote:
Originally Posted by mike@x-ph.com View Post
+1

first and second gear are too short to reach max boost, thats why datalogs are always done on higher gears
Cool, I'll pull a 3rd gear log later this week. Doing some additional research, I think getting my mdm changed to euro mode might help with the power cuts I am feeling
I was just about to post asking what driving mode your doing the 1st and 2nd gear pulls in. I would honestly find somewhere safe and try it with DSC completely off.
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      Yesterday, 08:48 AM   #6
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Quote:
Originally Posted by Beyond Help View Post
I was just about to post asking what driving mode your doing the 1st and 2nd gear pulls in. I would honestly find somewhere safe and try it with DSC completely off.
Itís better with DSC completely off. I am hoping euro mdm bridges the gap.
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