Help fund the VFR header

Discussion in 'General VFR Discussions' started by RVFR, Jan 24, 2017.

  1. CandyRedRC46

    CandyRedRC46 Member

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    Some of those assumptions are correct and some of them are incorrect. Yes the cam specs are very mild. Yes the static compression (piston and combustion chamber volume influenced) is very mild. No the valve sizes (which are a direct result of the RC45 lineage) are relatively huge. The intake and exhaust valves (though not titanium) are bigger than any of the gsxr750's and comparable to early 2000's super bikes. The valves of the VFR800 are in no way a limiting factor, they are ridiculously sized and complete overkill for a bike of this nature. Now the porting could definitely use some work. The throttle bodies are of decent size for a bike of this nature. I had mine over-bored to 38mm's and gasket matched the cylinder head intake ports and didn't notice much, so I would say the throttle bodies are fine until you start getting into big cams/head porting/high compression/overbore cylinders etc. Also worth noting, the bore:stroke ratio and even more so, the Rod:stroke ratio of this bike is absurd (again more aggressive than any of the gsxr750's) for a touring bike of this nature/power level, which is obviously a direct result of again, it's racing lineage...



    RC46 VFR800/RC45 RVF750 Intake valve 29mm - Exhaust valve 24.5mm
    GSXR750 2008 Intake valve 29mm - Exhaust valve 23mm
    GSXR750 / GSXR1000 2000-2004 Intake valve 29mm - Exhaust valve 24mm
    GSXR1000 2005-2008 Intake valve 30mm - Exhaust valve 24mm
    GSXR1100 Through 1990 Intake valve 28.5mm - Exhaust valve 25mm


    RC46 VFR800 bore & stroke 72mm & 48mm Ratio = 1.5 (extremely oversquare)
    2006 gsxr750 bore and stroke 70mm & 48.7mm Ratio = 1.437 (relatively long stroke)


    VFR800 RC46 Rod length : Stroke 102mm and 48mm = 2.125 Rod to stroke ratio which is again ABSURD in anything other than a dedicated race bike or F1 engine
    2008 GSXR750 Rod length : Stroke 95mm and 48.7mm = 1.95 Rod to stroke ratio which is again, relatively mild, when compared to the VFR800


    Large valves, large bores, short strokes, long rods are all things that you want in a High RPM, dedicated race engine. Why these things were trickled down from the RC45 to the RC46 is beyond me. How Honda got this bike to perform so well in the low to mid RPMs is pretty amazing when you think about, but it is definitely a testament to the mild cams/porting/throttle bodies/compression and tuning of the factory VFR800/ RC46...
     
    Last edited: May 12, 2017
  2. Gator

    Gator Insider

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    I understand about the valve size but you get the idea od what I'm talking about, it would take a lot of money and time to really see the potential of the motor. The Tuono motor is a bad ass V4 .
     
  3. NorcalBoy

    NorcalBoy Member

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    I can tell you the cost of a superstock 6th gen build is equal to about 1.5 - 2 5th gens, or one 8th gen standard. Crank and rods alone are about $2k.
     
  4. Badbilly

    Badbilly Official VFRWorld Troll Of The Year!

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    So how many pesos would a dude have to chuck toward a recent vintage VFR to get it up to what a GSXR 750 or litre bike will do on a drag strip or horsepower contest?

    Engine building ain't nothin new. Some outfits if they were to have lots of pesos and wanted to build a VFR engine might use the block and head castings and maybe the crankshaft if it passed inspection.

    Then we got the old DNF factor to toss into the equation. Dude can stick 5-6 grand in an engine faster than a lawyer can bill by the hour..No offense to most lawyers of course.

    Heres one outfit of good reputation that has speed goodies for bikes and cars. With some drilling down until the peso stack bottoms oot there are just tons of things that can make a bike fast.

    http://www.wiseco.com/Catalogs/Motorcycle.aspx






    IMO, doing the math ain't aboot nothin. Forking over the pesos is what it's all aboot.
     
  5. CandyRedRC46

    CandyRedRC46 Member

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    A good idea of what can be done with out going bankrupt is Highsidenz's build. He hit 136whp (compatible to a full exhaust and tune gsxr750) with following:

    Lady Bird rc45 full system
    Custom cams ground to Rc45 (plus a tad more) specs
    Cbr929 pistons resulting in about 13:1 and 825cc's
    Air box mods
    Rapid bike race module and custom fuel/ignition tuning.
    Probably a few other things I'm forgetting.

    Sent from my Nexus 6 using Tapatalk
     
  6. Badbilly

    Badbilly Official VFRWorld Troll Of The Year!

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    Most of us are not familiar with this post/engine or owner. Lots of those little things that are forgotten can add up in a hurry. The major forgotten component is the labor. In real terms for the average dude here with a few exceptions does not have CNC mill and lathe for even boring out a block to fit those nifty pistons.

    We are talking dollar amounts here not theory. For those who have the pesos fine, for those who have the facilities fine, for those who want a specialty bike fine. Been there done that, had a shitload of Tshirts and ain't a lot of it free.

    Looks like now just swapping air cleaners is the thing to do.
     
  7. Gator

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    What was the cost Candy?
     
  8. RVFR

    RVFR Member

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    Ooo... yes Cams ;) and a decent air cleaner.
    Another part to the KN conversation was the one dude was talking about seeing if a cold air intake with tune-able ports would be doable, Yea, if only. But I liked his thinking.

    I ain't done...
     
  9. RVFR

    RVFR Member

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    Yes Highsides build was crazy cool took a belive over a year as he was testing and writing theory to why it should work. The part with using 929 piston was interesting as the pistons needed to match what Honda used in materiel in the VFR cylinders and the 929/954 did then he milled the correct amount off the 929 piston to get the right CR. matching the combustion chamber. With the Head he proved the head would work way past the 150hp mark, as he was thinking to swap valves. But after a flow test he found that wasn't necessary. So yes to what BB said, if you have the time and tools to do this, but I'd hate to calculate the cost in RD time.
     
  10. NorcalBoy

    NorcalBoy Member

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    There is no replacement for sheer displacement.
     
  11. OOTV

    OOTV Member

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    So how does all of this affect the header build? Based on RVFR's readings, does this mean the TBR is not all that it's been built up to be? I mean if to get the ultimate HP and power curve out of the VFR means tweaking a whole bunch of other things, apart from headers, does this negate the header build? Is it back to the drawing board in regards to the headers? Does this mean that rather than just a header, his guy(s) need to make a complete kit?

    I know that RVFR is trying to get his bike as improved as possible but if this means it's going to require more than just a header, what does that mean for others who are looking for just a header? If we take the last two performances at face value, a cat-less and lighter version of the OEM might be the way to go for the masses. Otherwise I see a lot of R&D going into this and from the lack of donations to his go fund me account, most people don't seem to feel the R&D is worth it.
     
  12. NorcalBoy

    NorcalBoy Member

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    I have a cad drawing laying around somewhere for a cold air intake directly through the top of the tank. I never got around to doing it. Again, not a cheap proposition. There isn't a lot of room under the headstock to access the airbox from the front. I ended up going half way and completely insulating the airbox, bottom of the fuel tank, and the fuel lines to the throttle bodies.

    [​IMG]

    [​IMG]
     
  13. Gator

    Gator Insider

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    Other than NOS, turbo and super charging. lol Harley has not figured out the displacement thing. An amazing amount of displacement for such little HP.
     
  14. CandyRedRC46

    CandyRedRC46 Member

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    Yeah I am still not completely sold on RVFR's two dyno runs as they werent back to back, I am questioning the validity of them. Being that they were a year apart, much different conditions and the first run, a 112whp slip on and tune is unheard of, but again, I am sure RVFR will get to the bottom of it.
     
  15. CandyRedRC46

    CandyRedRC46 Member

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    I am wondering how much of Highsidenz's 929 piston gains were from the displacement increase and how much were from the slight unshrouding of the valves and the huge compression boost.

    On a side note, after sitting in 100* traffic for thirty minutes and your nuts begin to roast, all that insulation starts to look like a god send.
     
  16. CandyRedRC46

    CandyRedRC46 Member

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    I wish I could easily tag him in this thread to see what he has to say.
     
  17. RVFR

    RVFR Member

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    Yep, I'm on the re do to what happen last year, was it the outside temp with the right amount of humidity? only way to know is almost back to back runs. After the KN air filter swap and run, I'll definitely know if going back to the stock header is the way to go, from that we'll have numbers to make a decision on the header build. But it's looking more and more the 2bros was full of dyno butt feelings and no hard facts, at least with how it worked on a 98-99 That said, take away my first dyno from last year, the 2Bro did gain from the stock before tune, so??? is it still worth it ? to soon to tell.
     
  18. Gator

    Gator Insider

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    Other dyno factors, tires, size and psi. And as Norca said, Dynojet.
     
  19. Badbilly

    Badbilly Official VFRWorld Troll Of The Year!

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    "Ain't no substitute for cubic inches" was probably coined by some old Chinese guys, some old Chrysler Hemidoods or some harleydoods.

    We can be reasonably certain that anyone who said "There ain't no substitute for cubic centimeters" wasn't a red blooded American.
     
  20. Badbilly

    Badbilly Official VFRWorld Troll Of The Year!

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    Did you mean to say NOStalgia? ;)
     
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