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Performance camshafts for F4i?

  #1  
Old 10-06-2010, 03:10 PM
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Default Performance camshafts for F4i?

I lead the engine development for the Texas Tech Formula SAE team and for my groups project we might be looking to use performance camshafts since getting enough air in the engine is difficult because of the restrictor. Does anybody know of any good shops that sell or grind cams and for the F4i and what their prices are?

If you want to learn more about my project check out my other thread
https://cbrforum.com/forum/new-member-area-5/hello-117157/
 
  #2  
Old 10-06-2010, 06:40 PM
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You should've combine the 2 threads. Porting alone will give you slight gains. Camshafts alone will do the same. Match them and you'll really see some improvement. For cams, contact either Webcams or Megacycle. Both are friendly, knowledgeable and can help you pick a grind. Don't go too crazy on the porting and practice on a junk head if you've never attempted it. I did one for my RR few years ago. Intake was smooth as baby's bottom and runner was sharp enough to cut yourself on. Bike wouldn't get out of it's own way leaving starting line. Did some research and found out it needs to be a lil pourous to break up fuel (atomization I think it's called). Last one I did I just mildly cleaned up casting imperfections. When I get ready to get head on my XX motor done, I'm gonna leave it to the experts LOL. Good luck with the project!
 
  #3  
Old 10-07-2010, 12:09 PM
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Originally Posted by cbr900racer77 View Post
Did some research and found out it needs to be a lil pourous to break up fuel (atomization I think it's called).
On the intake correct. Smooth walls tend to pull the fuel out of the air and have it stick. The exhaust can be as smooth as possable.
 
  #4  
Old 10-09-2010, 02:51 PM
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for most applications (fi, not dfi), i've heard it's best to roughen the area between the manifold/intake ports( where your injectors spit) and fade it into smoothness leading into the head and same going into manifold, that way the air comes in quick and then causes turbulence to help mix the fuel.
 
  #5  
Old 10-10-2010, 04:26 PM
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There are so many differing opinions on porting I gave up trying to get a handle on it. Some were porting the crap out of it, some swear going smaller makes more power. I just let Starr racing or APE do my heads now (alot less headache, not counting the wallet LOL)
 
  #6  
Old 10-11-2010, 02:17 PM
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Smaller ports create higher air velocity which helps atomize the fuel among other things. Larger ports slow the air down. Going bigger dosen't always flow more air either. If you kill the short side radius when you hog the ports into sewer pipes then you just killed the flow.
Porting is in no way, shape or form something people should do on their own unless they've already practiced on junkyard heads many times and know what their doing.
 
  #7  
Old 10-13-2010, 11:30 AM
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flowbench + extrude honing + multiple designs + lotsa dyno runs = win

generally you want to dyno your bike first to see where it's making power and where you want to make power. smaller ports = velocity = better power down low. bigger ports = less velocity but more cfm = more power up top. unfortunately it's not just that easy because if you open up the ports without changing the cams or doing other modifications where the extra cfm is needed, you'll PROBABLY lose power everywhere in the rpm range.

for most applications where people just want a general increase, it's best to just smooth things out (casting marks/rough areas, etc), but as mentioned, lots of practice on junk heads is required.
 

Last edited by madman; 10-13-2010 at 11:34 AM.
  #8  
Old 10-13-2010, 03:19 PM
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All this is great information. I've heard many of these techniques being used. We are looking for low end power so my guess is cleaning up the casting marks and just have a general port job. Could I interchange different cams from lets say an F4i into an 600RR? Just wondering because we might find a great deal on a rr and want the lower torque cams from the F4i. It just popped in my head-
 
  #9  
Old 10-14-2010, 10:46 AM
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Im pretty sure they don't swap.

You said in the first post you wanted performance cams, and in the last post you said you wanted low end power. These are conflicting wishes. Performance cams increase duration which causes more overlap, lower cylinder pressure at lower rpms means less power but more HP on top.
 
  #10  
Old 10-14-2010, 11:36 AM
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+1 Not many aftermarket cams out there boasting low end increases. If low end is what you're mainly after, you might be better off degreeing the stock ones. Spreading the lobe centers will help on the bottom but be prepared to give up a little topend.
 

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