Dyno numbers - 2.5inch Headers vs Stock headers

sunny said:

alright, can some one explain why my gas consumption has increased by 30% with new headers and open exhaust? and my riding riding is same as before, nothing changed.

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Penner said:

If your O2 sensor is located too far to the end of the exhaust system, it will get O2 from the outside air that pulsates back through the open exhaust. This (false) readíng will cause the ECU to increase fuel.
If ýou are on a dyno to get a map, disconnect the O2 sensor and switch it off in Tune-ECU. And keep like that after it is mapped.

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sunny said:

2 years ago I disabled o2 sensor in the tune map you created and sensor has been removed physically from the bike altogether. I have been running without o2 for 2 years and while having werkes + stock headers + DNK air filter.

only recently I changed to big headers + open exhaust and there is no place to install o2 on that at all.

Also the dyno i did few days ago, the dyno machine guy said the AFR is off on his machine by 0.4 so it should be 13.5 where its 13.1

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dougl said:

So it is leaner than the chart indicates?

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sunny said:

so I called dyno shop again and they said "they didnt know that they had new o2 sensor installed prior to day before I did dyno so the readings on chart is accurate" but when I was there they told otherwise about 0.4 difference but its all good now the chart reading for AFR is correct.The reading in your chart is

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Penner said:

The AFR in that chart is about 14.2. You get max power with these engines at an AFR of 13 to 13.2. So yours is definitly too lean.
To be safe you can even go to 12.8 and just lose marginal numbers.

As the O2 sensor can not be the reason for the increased consumption, there is another phenomenon with open exhausts.
They usually lose quite some power at low revs and the ECU delivers too much fuel. If you have been mostly riding at revs up to 3000 this might be the reason.

Anyway. Go to a qualified dyno operator, that knows how to work with Tune ECU and let him fix it.

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sunny said:

nobody near me within 100-400km radius knows or want to touch triumph for tuning, As soon as I say triumph they say no, all they do and want to do is harley+japenese, even though I told them I will bring my own tuning application+ tablet, they said no. I called all people in 100km radius while ready to pay 500+USD for tune but they kept saying no so its really tough for me to find "qualified Dyno operator" who can do tuneecu.

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dougl said:

Not surprising they won’t use Tuneecu. I don’t know of anyone close to you but Carpenter Racing in NJ (I believe) and 2WheelDynoWorks near Seattle can do it. There are definitely others around the US. Any Dynojet tuner should be able to tune any EFI bike with a Power Commander (PC). They sell a PC6 for the 2020 Rocket but it’s not listed for later years. If a Dynojet tuner tells you they can tune a PC on a Harley but not a Triumph, it’s BS. If they tell you that you need an O2 sensor to tune a Rocket with a PC, I would call BS on that too. Even if you find someone who’s willing to do it doesn’t mean they’re going to do it right. The typical software protocol for Dynojet is automatic tuning where they run it up and down and automatically fill in the trim table. They should be able to do it manually, holding the dyno at constant throttle position to over a range of rpm. This is what they would have to do with Tuneecu. Or at least be able to confirm their automatic results manually at discrete rpm/TP points.

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sunny said:

I am looking into buying more tools and street tune it on my own.

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Penner said:

The AFR in that chart is about 14.2. You get max power with these engines at an AFR of 13 to 13.2. So yours is definitly too lean.
To be safe you can even go to 12.8 and just lose marginal numbers.

As the O2 sensor can not be the reason for the increased consumption, there is another phenomenon with open exhausts.
They usually lose quite some power at low revs and the ECU delivers too much fuel. If you have been mostly riding at revs up to 3000 this might be the reason.

Anyway. Go to a qualified dyno operator, that knows how to work with Tune ECU and let him fix it.

Click to expand...