1 fast z Posted September 4, 2008 Share Posted September 4, 2008 I am setting up a set of aftermarket HKS cams for a 26. I have used 110 Degree center before for a lobe center between the IN and EX cams, but not sure if I should set them up with the same again, although it made good power in all areas. Just trying to pole and see what others have done on RB's. Quote Link to comment Share on other sites More sharing options...
1 fast z Posted September 10, 2008 Author Share Posted September 10, 2008 Its hard to belive that with all of the HIGH HP RB's, there is no one that has some first hand experience on Degreeing TURBO RB cams, as far as how far retarded and/or advanced you guys have set the cams. I am basicly just trying to poll on what others have set theirs at. Quote Link to comment Share on other sites More sharing options...
Careless Posted September 10, 2008 Share Posted September 10, 2008 I think most of the RB guys set to factory specs and had the machine shop worry about matching what the FSM says. :-/ Quote Link to comment Share on other sites More sharing options...
cheftrd Posted September 10, 2008 Share Posted September 10, 2008 110 for the intake. 115 for the exhaust. Dyno tune from there. Quote Link to comment Share on other sites More sharing options...
1 fast z Posted September 10, 2008 Author Share Posted September 10, 2008 110 for the intake.115 for the exhaust. Dyno tune from there. Dont you mean 55 degrees off of center for the intake, and 60 degrees off of center for the Exhaust? Quote Link to comment Share on other sites More sharing options...
Careless Posted September 11, 2008 Share Posted September 11, 2008 does this look remotely correct? Quote Link to comment Share on other sites More sharing options...
cheftrd Posted September 11, 2008 Share Posted September 11, 2008 Dont you mean 55 degrees off of center for the intake, and 60 degrees off of center for the Exhaust? No. I mean 110 degree lobe center for the intake and 115 degree lobe center for the exhaust. Lobe center is the point on the cam where the valve lift is exactly between opening and closing. 110 degree intake means the valve is exactly at the mid point in its stroke at 110 degrees ATDC on the intake stroke. 115 degrees exhaust means the valve is exactly at the mid point in its stroke at 115 degrees BTDC in the exhaust stroke. You're thinking of LSA which is lobe seperation angle. This is the seperation in degrees between the intake and exhaust lobes for a cylinder. LSA means nothing without knowing at what degree the valves open and close respective to the crank angle, only the relationship between intake and exhaust cam. The LSA for lobe centers of 110 and 115 is 112.5. This is pretty good for turbo engines. The narrower this angle, the more overlap, which is a bad thing in turbo engines. Many NA engines like LSA's of around 106 to 110. You could drop the LSA in the RB to 106* and make it all lumpety-lump, but you'd lose low and midrange power. http://compcams.com/Technical/TimingTutorial/ Quote Link to comment Share on other sites More sharing options...
1 fast z Posted September 12, 2008 Author Share Posted September 12, 2008 Basicly it works the same way, as finding TDC on #1, 6 piston. Then finding Center of Max lift on each cam, with the #1 piston at TDC. Then rotate the intake cam clockwise if looking at the front of the motor 55 degrees on the cam, which would give a 110 degree on the crank. Then do the same operation on the EX cam, but rotate it 57.5 degrees counter clockwise if looking at the front of the motor, which would give 115 degree center line from the crank. Atleast this is how I look at it. Quote Link to comment Share on other sites More sharing options...
Careless Posted September 13, 2008 Share Posted September 13, 2008 Isn't that what seat-to-seat primary timing is ? taking note of IVO, IVC, EVO, EVC and at what degree of rotation it happens... ? Quote Link to comment Share on other sites More sharing options...
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