🛠 Why some cylinders run hotter than others? | TECH TUESDAY

38 Comments

1. Tech Tuesdays are back baby!!!
   Some engines are more prone to this phenomenon than others but the problem of one cylinder running hotter than others is a common one across most internal combustion engines.
   In this episode of Tech Tuesday, we explain why this happens and offer some common sense solutions.
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   Liked this video? Here are more like it:
   EGTs Explained: https://youtu.be/-NoFfck5v4c
   Turbo or Supercharger: https://youtu.be/BxIxmO37Lkc
   Hall Effect or Reluctor: https://youtu.be/lTAW0lTqP6s

2. What are youir toughts on diffusor plenum, to equaly distribute the air to each cylinder rather than a big plenum?

3. Hi Matt, another great video. I have a question regarding exhaust flaps or bypass's. Do most guys use their ecu (Haltech) to trigger these? Ive heard conflicting stories on what way to hook them up?

4. Very well explained. I learned something new. Thanks

5. I like 👍

6. I'd love to see a Tech Tuesday session on how the average person with average wiring knowledge can power up their Elite ECU and IC7 dash outside of the car to get them configured prior to actual installation in the car.

7. It seems like a simple experiment to prove this would be to make a "mirrored" manifold that is fed from the back. If the front cylinders run hot, it must be the airflow. Has anyone ever tried that?

8. great gem of knowledge. Just proof that we know less than what we think.
   I woudlk be interested in knowing how to set up an engine for both Gasoline and also LPG and the difference in operation, if any.

9. What about the G force which push everything back during acceleration ? Does it affect noticeably on the the inertia and mass of air under these hard acceleration? I think it has some effects.

10. Could you possibly solve it with separate throttle bodies with separate maf sensors? If you really were in an ovecomplicating mood.

11. BRAVO you guys are STARTING to wake up but you only just touched the truth near the beginning of the clip. IT IS THE COOLANT distribution and please take no notice of the guys racing as they were shown the TRUTH in the days of Bathurst and the phase III. We have 30'000 hours of engine dyno work to be able to justify what I am saying. We did all of this back in the nineties.

12. Yes your tec advice .is on key.

13. What about reading the O2 sensor on each individual exhaust pipe, and there you can see how much air is one cylinder getting by looking which one is leaner ?

14. Scenario: you don’t have individual cylinder EGT. You have a 4 cylinder engine and blindly think it may heating the rear.

    You add say 5% additional fuel to number 4 at the rear and 2.5% to number 3. Do you now have to be careful of your lambda target if running a single lambda sensor in downpipe? Reason being the lambda sensor reading is an average reading: you don’t know that 3 and 4 were potentially running lean and now through the average lambda target you have effectively leaned the air fuel ratio in number 1 and 2 by c. 3.75% fuel per cylinder if you are targeting the same lambda target.

    At 11.5 afr that would mean cylinders 1 and 2 could be running 11.9:1 on average and potentially leaner on an actual cylinder given different distributions. This appears a potential issue with blindly richening cylinder fuel trims.

15. Any insight on why the back of the n/a bara is hotter? It's mid injected for the air flow and nice and long.
    I had the same on an intech as well and they have that whole venturi thing in them.

16. This was another one for the books, nice discussion and the in-mix of pragmatic thinking together with science was pretty decent. The topic was approached from some perspectives I didn’t see coming, but, what’s worth the while mentioning is that Haltech have been retaining EGT meters that work hand in hand with their ecus for a very long time.

    While this might not seem like too much of a fuss, think about it from a consumer’s perspective. Having access to an out of the box EGT solution which works without fuss so data logging accurately becomes no trouble at all. Then, couple the after sales service and technical support Haltech can offer to ensure the absolute best value can be unlocked from the investment and you have a clear cut win-win scenario.

    Thanks again for this one Matt, cheers to everyone making these videos possible at the Haltech Head Office!

17. Awesome Info! This was really interesting!
    I always thought the rear cylinders were being starved from air because of tapered intake manifold design, etc… But that would leave them cooler because they would be running richer 🤦‍♂️
    Physics for the Win! 👍

18. Thoughts on individual runner widebands over egt Probes

19. hot rear cylinders from lack of external air flow. even water cooled engines need air flow externally.

    buy the time air has passed through intercoolers, radiators etc obstructing air paths the under hood temps at rear of block are increased.

20. Matt, would running a different heat range spark plug for the hotter cylinders help? Or is that an urban myth? How's the VW?

21. loved it. very analytical

22. 👍

23. Haltech elite 2000
    Would you statically make cylinder 6 use more fuel? Or is there a way to dynamically add more fuel to cylinders based off a deviation from the average egt of all cylinders?

24. Is there actual pure CHT metering available off the shelf? Would love to have for an aircooled application.

25. I've always matched the higher flowing injectors in the cylinders that receive the most air. I've always wondered how many people even think about this. Great video!

26. What about external airflow around the engine bay?

    And what about NA engines that are sucking the air in rather than being force fed. LS engines for example suffer with no. 7 & 8 running hotter. I run 2% fuel trim on the rear two cylinders on mine.

27. Thank you for the explanation Mark! I've also been thinking about this after racking up a couple of years of tuning experience.

28. The rear cylinders are closer to the heater, fact, but I'm no engineer.

29. And yet still people believe the cylinder closest to the throttle gets the most air. Great explanation!

30. It is because of intake manifold. Runner length ect… If you were n/a itb than you wouldn't have those anomalies.
    On k24 rbb intake mani cyl 2 i the worst and cyl 1 is the best.
    Don't ask me how I found out this…

31. thanks god i only have one cylinder in my motorcycle

32. These are great, lfw engine what’s the go there?

33. Great episode. Very informative.

34. your right matt noticed this on spark plugs that cylinder 1 is always richer than all other cylinders for some reason

35. What about when you add another 10+% of fuel in the hottest cylinder and its still hotter than the rest, and you can't add any more trim because you start having plug fouling on idle due to too much fuel? Is there anything that can be done with ignition trim for that cylinder to add a bit of safety? Would it be wise to retard that cylinder a degree?

36. Can we use wideband sensor for each cylinder

37. There is reason subaru runs knock sensor on cylinder 4…

    Yes that one runs hotter than other…exhaust port S turn doesnt help.. plus with unequal length header making it even worse and more prone to heat and detonation…

    Keep cyl.4 happy, the rest of piston will be happy too.. (unless there is stuck injector on tue other cyl)

38. 👍

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