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Post Info TOPIC: 08 dyno numbers seem low


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08 dyno numbers seem low


All,   I dyno'd my 08 busa with full R77 pipe today.  It was on a DynoJet, and the results were lower than I expected.  Pulls were done in 4th gear, and I have been auto tunning.  The AFR was pretty consistant around 13 to 1.  Yet it only pulled 170HP and 101FT.  What can I tweek to gain the other 10 to 15 HP I see others easly get with a full Piped Busa? I'll update the charts later today. Thanks in advance guys, and just as an FYI, I am a site donor

 



-- Edited by nitro71455 on Wednesday 13th of June 2012 12:36:04 PM

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I have Said it on here b4 & I will say it again(Even though Many Will Disagree with Me....Here it goes), 13.0 AFR is to RICH!!! Ya, Sure it's on the Safe side of the Tune, But for Max HP lean her out a little.

****USE THIS INFO AT YOUR OWN RISK**** But I always Tune to 13.5 on 92oct Pump fuel. My 08 Busa(Valve cover has NEVER been off), Just Bolt on's with a Alien Head exhaust(Now it has a Side Winder) made 180.5 HP & 104.4ft! This was about a Year ago too............. Still Going Strong!!! wink

 



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One question is, what O2 controller are you using when auto tuning to 13.0:1? There is one very popular brand that reads lean (leading to rich tuning) compared to others.   However it sounds like the dyno's o2 sensor reading agreed with your autotune.

Therefore I would also consider that, no two Dynojet dynos are alike. Their ability to ship a dyno with the correct moment of inertia (as stamped on the drum) and coded into the software is pretty poor. I saw first hand during training that the unit we were using didn't have the right value entered in the software. When I cam home and checked my own unit out, sure enough, mine was sitting at the default of 14.000 too.  Yes they charged me to fix it and correct it in the next software release sent to me.  Then I read Cycle canada's test comparison of multiple Dynojet dynos and saw that others see inconsistencies too. Mark Salvisburg keeps a copy here:

http://www.factorypro.com/magazine/mag_cyclecanada_Dynojet_dyno.html

Keep the above varyability in mind when comparing dyno numbers.   If your O2 sensor controller and the dyno agree and you feel for certain that your AFR was good, then the problem just might rest with the dyno.

How many pulls did he make when they determined what your peak hp was?  

One thing I can't see is what the actual correction factor is. e.g. 1.01 or 1.02 or 1.30.   I don't know if Dynojet still posts the actual value on the chart (I haven't used Dynojet equipment and software since the early 2000's) Correction factors larger than ±7% are not comparable for SAE standards.   So for us lucky guys living at sea level our 0.98s and 1.04s are great.   Folks living in Denver with 30% correction factors have too much mathematical error to compare to standard conditions.  That's not my idea, its the SAE's.  So if you have a chart that has CFs of anything bigger than 1.07, you can start to consider only comparing to folks within  your region.  For individual comparison a CF of 1.30 is very comparable to a CF of 1.32  just don't expect to see exact same values when your test was at 1.30 and the guys with similar mods are posting with tests performed at 1.02.

 

Hope that helps somewhat.



-- Edited by Craig on Monday 18th of June 2012 01:45:00 AM



-- Edited by Craig on Tuesday 19th of June 2012 12:00:42 AM

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