Dyno Disappointment

Discussion in 'Mechanics Garage' started by whiteknuckles, Oct 10, 2015.

  1. whiteknuckles

    whiteknuckles New Member

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    Just got my '02 back from the performance shop with a new PC5 and two brothers slip on. Has 35K on the motor. Only managed 90 rwhp despite upgrades and K&N air filter. Kinda bummed. The Two Bros only runs through one of the cans, so the other is for looks only. It's not the "stash" can, so I'm disappointed on many levels. Sounds fantastic though, so that's a little comfort. Any one have any idea why my hp numbers are so low, or is this as good as it gets w/o a full exhaust or cat delete. PAIR delete and flapper valve done alredy.
     
  2. Knight

    Knight New Member

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    Did they give you a comparison graph/numbers of before vs. after?
     
  3. whiteknuckles

    whiteknuckles New Member

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    No before and after. Definately pulls hard, faster and smoother through the powerband. Just wondering if this is as good as it gets w/o more work on my end, like a cat delete.
     
    Last edited: Oct 10, 2015
  4. TNRabbit

    TNRabbit New Member

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    O had my stock 5th gen (98) on a dyno last year & it was at 106 hp at the wheel with only a D&D can--NO mods.....YMMV
     
    Last edited: Oct 10, 2015
  5. RVFR

    RVFR Member

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    Why 5th gens rule ;) But that is surprising, wonder what Candy will throw out on this. awe, now I read your in Oregon what shop? EDR is great for this sort of thing.
     
  6. Arnzinator

    Arnzinator New Member

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    Hopefully CandyRedRC46 chimes in on this. If I remember correctly he has a very detailed thread with all the mods done to his bike. Specifically how each mod affected power. He was running mid 10's in the 1/4 mile @ 130 +/-.
     
  7. whiteknuckles

    whiteknuckles New Member

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    That's where I had her done. Great shop.
     
  8. baz263

    baz263 New Member

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    I can understand your disappointment. On the bright side, it's only a number on that particular Dyno. Each are calibrated as individual units so the results vary. My 97, PC3, Staintune and K and N, recently ran 95 rwhp whereas previous VFR 's have been much higher. My 89 coincidentally ran 89 rwhp. Just numbers unless you have a basis for comparison. :D

    Sent from my SGP512 using Tapatalk
     
  9. Knight

    Knight New Member

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    That is the issue, the number is relative, it is not absolute. Based on your feel that it is pulling harder, and the shop's reputation, it sounds like the bike has gained some power, usually somewhere in the 5-10 hp range, throughout the band.

    They screwed up and should have done a reading with the totally stock bike. That reading most likely read a handful of horsepower lower than the final number.

    That peak power number you were given may be 10 hp lower than another shop may indicate for the exact same test. Different software and different hardware is actually going to use different calculations and assumptions to arrive at a number based on the torque from the bike. Also, like baz said, they are also calibrated differently.

    All of these shops should calibrate around the mark where power is being measured. I would have a calibrated industrial motor of 100 HP, drive the dyno with it, and calibrate to it. Then the dyno may measure far off at 10 hp or at 200 hp, but it would be dead on around 100 hp where they are measuring. (These things are always trade-offs.) Doing such, the shop would establish some agreement with all of the other shops, and get rid of any confusion. However, they have no interest in agreeing with each other, just in getting your business.

    I have worked extensively in laboratories with scientific measuring instrumentation where technicians have repeatedly used equipment not calibrated correctly. Everyone has their opinion on how things can work and should work. Ask 10 people and you get 10 different answers. Such are people, and these various opinions are unfortunately reflected in the numbers everyone is given. So do not take that peak number literally.
     
  10. whiteknuckles

    whiteknuckles New Member

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    Thanks for the info about dyno variability. I'm keeping that in mind as I bemoan my results. My butt dyno and auditory dyno are happy with the results. I was a calibration tech in the navy so I'm aware of the "garbage in, garbage out" senario. As an aside, does anyone know what the calibration standard is for a dyno? I'm assuming it's a horse on a treadmill ;).
     
    Last edited: Oct 10, 2015
  11. Knight

    Knight New Member

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    My Google returned this PDF:

    http://www.iso376.com/calibration/dynamometer-calibration.pdf

    Early on it shows, "In essence, the operation consists in applying forces that can be accurately measured to a dynamometer and register the values provided by the electronic equipment connected to the transducer."

    It also refers us to the standard:

    "Calibration is usually performed by applying the protocol established by international standard ISO 376. Standard ASTM E 74 is also a protocol issued in the US."

    Test method documents usually require a subscription and cost money, unless you still have sweet sweet connections who can download them for you. For example if I read the ISO site correctly ISO 376 costs $138.
     
  12. RVFR

    RVFR Member

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    Ya know this could be fun, have the VFR dialed in on one dyno , then go to another and see the diff. I know there is atmospheric conditions dialed in before hand as well, I'll have to drop Gary at EDR a call and see if they have any dyno days in the future planned.
     
  13. NorcalBoy

    NorcalBoy Member

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    What type of dyno was it? Edit...they are a dynojet shop.
     
    Last edited: Oct 10, 2015
  14. MPH Racing

    MPH Racing New Member

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    Also remember the stock HP numbers are at the crank not through the gearbox,chain and wheel. A dyno reads wheel hp not brake hp. there is about a 15-20% loss of power through the drive line.
     
  15. whiteknuckles

    whiteknuckles New Member

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    Thanks for that. The hope for 100hp + comes from various dyno charts I've seen here and other places on the web. I don't want to come across as a cry baby because I really like how my bike runs, rides, and sounds, so I am coming out ahead.
     
  16. CandyRedRC46

    CandyRedRC46 Member

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    1. Dynos should only be used as a comparison tool. Not as an end all be all number. A single dyno number is worthless with out a baseline.

    2. Kn filters are not a performance part for a vfr800. They have reduced surface area over stock and flow no extra over stock. Honestly I wouldn't be surprised if the kn lost HP over stock as it really messes with the distribution. Try again with the snorkel pulled and a Piper Cross filter, that might help.

    3. Pair and flapper delete aren't performance mods. The flapper opens at 6000 RPMs. It will not affect peak horsepower numbers. The pair valve leaks air into the exhaust after combustion, it has no effect on power output. It just needs to be removed for accurate air fuel readings of the o2 sensor.

    4. Don't expect just a slip on to add anything dramatic over stock besides weight loss. If you haven't noticed, there are two huge mufflers on the back of a VFR VTEC, they flow plenty. The real restriction is the primary/secondary diameter size on the factory header piping.

    5. Again a power commander isnt really a performance part. You're not going to magically gain any extra airflow or combustion pressure by simply setting the air/fuel ratio to where its supposed to be. It has no control over timing, throttle restrictions or airflow etc....The factory fuel mapping is a little lean in the 3000-7000 range, but it is fine up top at 9000 plus RPMs where peak power occurs...

    6. About peak power, did you look at the area under the curve, where the fueling changes were made? You should have picked up some decent power from 4000-6000 RPMs. How does the air/fuel ratio graph look? 13.2 across the board or all over the place?

    7. Don't expect any gains from a cat less eBay brand header. Been there done that with a motad header. It made no noticeable power. If you can find an old two brothers header / Erion racing header or they finally make a copy, those are the only ones that will make power.

    Moral of the story:
    If the AFR is solid, be happy or buy/make some actual performance parts and try again.

    PS sorry if this comes off as a being a dick post. Its more of a stop, relax, its fine post.
     
  17. vfr2k8

    vfr2k8 New Member

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  18. GreyVF750F

    GreyVF750F Member

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  19. NorcalBoy

    NorcalBoy Member

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  20. tyarosevich

    tyarosevich New Member

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    Yeesh, I was going to get a PC5, but I'm starting to wonder if my best bet with this bike is just shaving weight and not worrying about performance mods.
     
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