Thought I'd ask Chatgpt

bmw2800cs

bmw2800cs

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AI will undoubtably lead the path to our dystopian future, until then we can ask questions like this one :). Yes it got the stock carbeurator wrong on a 2800cs. Thoughts? How did it do?

Question:
If I put three Weber two barrel DCOE 40MM carburetors in my 71 bmw 2800cs and a more aggresive cam what will my horsepower be?

ChatGPT said:​

If you're putting three two-barrel Weber DCOE 40mm carburetors (total of 6 throttle barrels) on your 1971 BMW 2800CS (E9), and upgrading to a more aggressive cam, you're making serious performance modifications to the engine. Let's break this down and estimate horsepower gains.

​

  • Engine: 2.8L inline-6 (M30)
  • Stock HP: ~170 hp @ 6000 rpm (SAE gross), ~150 hp (DIN net)
  • Induction: Single downdraft Solex 4A1 carburetor (or sometimes Zeniths) - Wrong!
  • Compression: ~9.0:1
  • Very mild camshaft, built for drivability

Your Upgrades:​

1.​

  • Big improvement in airflow and fuel delivery
  • Much more responsive throttle
  • On a healthy M30, this alone can add 20–30 hp, especially with proper jetting and tuning

2.​

  • Higher lift and longer duration = more power at high RPM
  • Depending on the cam, expect another 15–30 hp
  • May sacrifice low-end torque for high-rpm power
 

Estimated Horsepower:​

Here are some ranges depending on how far you go with tuning:
SetupEstimated HP (Net)
Carbs + mild cam190–200 hp
Carbs + aggressive cam + headers200–215 hp
Fully built (head work, high comp, tuning)220–240 hp
Realistically, with triple DCOEs and a good cam on a healthy engine, 200–215 hp is a solid, streetable expectation without needing a full rebuild.

Notes:​

  • Tuning is critical – DCOEs must be correctly jetted for your engine and altitude
  • 40mm chokes are good for a 2.8L, but if you go extreme, you might want 45mm for top-end
  • Drivability: You may lose some smoothness and cold-start ease, but gain big in responsiveness and top-end power
Would you like help picking a camshaft spec or jetting for your Webers?
 
I have been very impressed with the quality of some of the responses I have had from chatGPT, and this on all types of subject,. Especially the new version 5.0.


Of course, it really pays to double check the responses if an important decisions hinges upon them. So I often ask "What are your sources for that information?"
 
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