Possible bug: Boxer-4, Single Barrel Eco carburettor


I’m playing current open beta branch of automation (Build: 200203.11823.1719.Manual). Found a bug while playing campaign, but all of the following metrics I have produced in sandbox.

You might want to check out Boxer 4, Dircet Acting OHC, (full cast iron) Eco Single Carburettor settings. I can only make them not knock with Regular leaded fuel in 1955 with quite extreme settings:

  • Minimal engine size: 50x50 mm
  • Compression 6.0:1, Cam 100
  • Standard intake, Fuel Mixture 13.2, Ignition timing 0, RPM limit 7500
  • Exhaust Cast Log, 12.7mm diameter, Second mufffler Reverse Flow
  • All quality sliders at default 0

They can’t really be this bad, right?

Why I believe this is a bug:

  • No other engine acts this way
  • Octane ratings for other Boxer-4 carburettor configurations, with all other settings the same:

Single barrel,single carburettor: 74.8 RON
Single barrel, twin carburettor74.0 RON
!!!Single barrel eco, single carburettor 92.0 RON !!!
Single barrel eco, twin carburettor 74 RON
2 barrel, single carburettor 74,8 RON
2 barrel, twin carburettor 72.9 RON
DCOE, Singe carburettor 73.7 RON
DCOE, Twin Carburettor 72.2 RON

  • In comparison, Boxer 6, Direct acting OHC, all other settings the same
    SIngle barrel eco, sing carburettor 75.2 RON
    Single barrel eco, twin carburettor 72.9 RON

  • I checked all the other engine block types available in 1955, all of their single barrel eco, single carbs are ~75 RON. Boxer 4 stands out alone.

  • I checked all the engine block types in 2020: boxer-4 89.7 RON, all the others 73.5 ±1 RON.

  • I checked other valve systems for Boxer 4: all of their single eco carbs have abnormally high RON:s. PR and DAOHC 92 RON, OHC and DOHC 90.5 RON.

  • Therefore there’s some bug in single barrel eco, single carburettors setting files, that affects ONLY boxer-4 engines. Misstype in a datasheet, I presume.

Maybe this bug has slipped by, because who the heck uses boxer 4 engines anyways. :stuck_out_tongue:

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Just venturing a guess, but I would say Volkswagen and Subaru.

As far as answering the post I have no idea but I’m now curious and I’ll see if I can replicate it.

Do you have a screenshot with the stats handy?

Just checked, it is a disproportionate octane rating.

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I can verify that Boxer 4 engines are a bit borked with Single Ecocarbs. The valve configuration doesn’t matter much, B4 engines with single ecocarbs end up with about 100-mid 90ish octane, even after reducing compression to minimum. Doesn’t happen with Boxer 6’s.

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This bug’s real…

1x Ecocarb

2x Ecocarbs

1x 1 barrel

1x 2 barrel


I’m on the Open Beta build.

Also, please note, the 1x Eco-carb allows me to have no pinging at 94 octane instead of 92 octane, lol!

EDIT: Fixed screenshot duplication, oops!

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This should be very easy to fix, I’ve put it on our list :slight_smile: thanks for pointing out!


I have assumed that this is some intended feature and never realised it’s a bug :wink: