Cool cam upgrade

[OB_Kirk]

I was on the phone with the nice lady at Web Cams. I asked her if they can do the "536" grind on both intake and exhaust cams. A "single pattern" cam set if you will. The answer was yes. This should be the largest cam set that will fit without running the chance of having to pull the head. It would be referred to as the 536/536 grind or you could just refer to it as the "Kirk Special", because I think that this is what I am going to do. It is .378" lift and 244 degrees @.050" lift.

[Guest]

Interesting,
Spoke to my builder today told me not to get yosh cams,
Told me to wait till he gets it apart so he can spec out the cams to web with the exact grind he decides upon.

[Frank Adams]

Don't say I didn't try to tell you about how well the 395 lift cams work with the Busa motor!

Maybe you didn't see My dyno chart? (not talking about overall hp either)

[OB_cbxchris]

Big Big mistake going with stock pistons on those grinds.....big mistake....you will be lucky to have 160 lbs cranking compression...plus I`d just about put money on it that you bend a valve or two. I agree with Frank...395 web is better but with pistons....I`d also look at megacycle cams real hard....they have a couple good grinds...will have better compression due to ramp speed on cams. I know I`ve been there...matter of fact still there...changes on the way this winter if I don`t turbo....

[OB_THE MOTORHEAD]

boooooooossssst

[OB_cbxchris]

MH you`re killing me............turbo fever....

[OB_Johnnycheese]

Yeah Motorhead is about to get me a divorce
I had to make some calls today.
Maybe the stroker was not the way to go.

[Guest]

Chris, your post basically repeated everything my builder said to me today about it.
Down to the word.

[OB_Kirk]

I know it is a different application, but NHRA Super Stockers are (to over-simplify) restricted to stock engine parts other than intake manifold and valvetrain. You would be amazed at the lift and duration at .050" that these guys run on 8.5:1 automatic trans equipped cars that are really heavy. It is not unusual for these cars to drag the rear bumper on the launch (they are not allowed wheelie bars). Compression is one way to increase horsepower. improving the engine's VE is another. It may not be the ideal, but if a big cam on a stock engine increases the engine's VE, it is going to make more power.

[Guest]

Kirk,
Yes, NHRA S/S cars use great big cams with low compression engines. And they are race only cars with absolutely no power down low. Your cam selection will work, but in the lower rpm,s youre torque output will be LESS than a stocker. This RPM range is where you spend 90% of your riding. The bike will feel slower.

[OB_Kirk]

Good point, but is 244 degrees at .050" really that big a stick? This is an 11.5:1 motor after all.

[OB_GSXRTURBO1]

Think in terms of a 4 valve motor and you will realize how big it really is.

[OB_GSXRTURBO1]

double post

[This message has been edited by GSXRTURBO1 (edited 08 August 2000).]

[OB_cbxchris]

Kirk to give you a idea...I have J&E 12.7 to 1 pistons...1mm over valves...which are seated around 15 thousandths out into the combustion chamber more than a stock valve(there is a reason for this) I have the smaller webs and my cranking compression is a measley 185 lbs....and I`ve tried all different lob centers...I`m very disappointed...its a great everyday street bike but without a doubt I will not race it....I`ll get my *** busted big time by a good engine...I`m not saying mine is slow just not going to run with the big dogs. I would guess mine has 190 hp...maybe a little less...it does have a good head. Compression is torque...think what kind of comp you will have with stock pistons. Even with pistons there is not a over abundance of valve clearance. You also need springs...badly. How can you properly set your valve springs up without head apart. Don`t try to half do it....there is no easy way out.

[Frank Adams]

A lot of people just tried to ster you in the right direction.

I hope it helps ya?!

[Guest]

"boooooooossssst"

dammit Den that's just wrong, you stop teasing us!!!

[OB_Kirk]

Yeah, I saw it Frank. Looks awful tempting. I just can't run the risk of purchasing cams, tearing it down, and then find that I need to pull the head for machine work. I am still wrestling with the idea of rolling the dice. I've got a few thousand more miles to decide. The 536/536 set would give up .017" lift on the intake side, but pick up 2 degrees of duration at .050" on the intake side. The exhaust cam is identical to the 483/536 cam set that you used.

[OB_Kirk]

Frank, I'm not sure I understand you. You and Dennis have a lot of experience in this area. I don't know the other guys. Are you still trying to sell me on the .395 lift cam? Everybody else seems to think it's a bad idea. I keep going back to the picture in my mind of a SS/PA '56 Chevy I saw make a pass. Stock compression 265 V8, 2 speed Powerglide automatic. It had a roller cam that was so big that the horsepower peak was at 8200 rpm. It still had enough poop to hike one front wheel on the launch. If the bigger cams will get me higher peak horsepower numbers, the Bus has a six-speed gearbox that will take advantage of it. If the nay-sayers are implying that there will be no torque gain, or that the torque peak will be moved up a bit, that's okay too. We are not talking about a 600 here. I am starting out with 100 ft. lbs. of torque at under 7000 rpm. If they are saying that there will be some huge torque loss, I'm not sure that I'm buying, unless you and/or Dennis concur. From the looks of your dyno chart, the torque peak moved up about 500rpm, and the horsepower peak moved up about 1500rpm. That is a wider powerband with bigger numbers to back it up. Doesn't sound like too much cam to me. I am inclined to try something a tiny little bit smaller on the intake side, and the same as you on the exhaust side, unless you or Dennis think it is a bad idea. I'd like your thoughts on this.

[Frank Adams]

Kirk, look at this way, call around to reputal speed shop and see what type of cams their useing in their motor packages.

They are useing the setups that they do for a reason.

I think you would have a different view of the cams that use if you were to compare My dyno sheet to a stock one. You can see how much more there working over the stock ones. And most importantly, you can see that they're still building hp at red-line!

My motor is NOT that big. 1360 12.7 to 1, no milling of the head or block. 120thou piston to valve clearence.

Now compare My dyno runs to Tom M's 3mm stroked motor.

Some bodies doing something right...!

(sorry Tom)

[Frank Adams]

Oh yea.. don't forget to look at what cbxchris is telling you, I think he has the same cams your wanting to use?!

BTW, you can't compare a Busa motor to a car motor. Come on Kirk!