Cam lobe separation?

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wistech · #1 Post by **wistech** » Sat Jan 27, 2007 4:14 am

I was just going to install the new performance cam in the 470. Now the dyno chart from the other engine showed a huge top end hit on the 460 with the cams degreed to 108. It would be so sweet to get to 60hp on this engine. This is uncharted territory with the cams and Im open to any data on cam lobe separation to go for absolute max hp. Im thinking leaving the intake at 108 and going to 110 or 111 on the exhaust. Does this make any sense for overlap or should we just try it at 108. I cant find any good intel on this subject at all. Maybe the rice burner web sites can help?

What did Toms 505 run his cams at the first time. When it had the big top end loss. I dont want to go that way.

cannondale27 · #2 Post by **cannondale27** » Sat Jan 27, 2007 6:56 am

Leave intake at 105 or 106 and exhaust same.You will have the big hit but it wont be at rev limit.Going 108 or 9 on exhaust will make it rev to moon but you wont feel a "hit" it just that you lose more at bottom and spreads it out.HP will peak within 2hp just in different areas and rates with cam timing changes.

wayneschofield · #3 Post by **wayneschofield** » Sun Jan 28, 2007 4:05 am

Dunno on the 'dale but I'd be tempted to run exhaust at 102-104 and the inlet at 110-112. I tend to find you'll lose through the middle and gain at the top, if top's what you're looking for anyways...

wistech · #4 Post by **wistech** » Sun Jan 28, 2007 12:18 pm

Just looking for a peak number on this engine to beat all the other 468 engines so far. . I did a ton of research last night. Didnt find a whole lot. Hard to find much on high revving singles. The stuff I did find suggested retarding the intake around 115 and the exhaust around 110 for ported heads. Since I know 108 is the magic number for stock cams Ill try to keep close to that and see what just the updated porting and exhaust cam will do. . Some of the ducati engines were over 125 . Not a whole lot of logic supplied on the whats and whys of LSA and which way to go. Id love to try them all but dyno money is in short supply and I will only get one shot so its going to be best guess as usual.

cannondale27 · #5 Post by **cannondale27** » Sun Jan 28, 2007 12:19 pm

Here is one.If a given motor which has 11000 rpm rev limiter hits this normally and peak is made at limiter.Change is made to cam timing and peak power occurs at 7000rpm and motor hits 11000 rpm rev limiter so weakly it is almost not there.The 7000rpm motor will "feel" like it has a huge topend because it will rev instantly to that top end.Only problem is that 7000rpm motor isnt using all the revs its capable of.

wistech · #6 Post by **wistech** » Sun Jan 28, 2007 4:08 pm

Thats pretty much what happened when I set the cam timing on a stocker to plus 2 degrees . Gobs of usable low end/mid range torque like it had a stroker but major loss of top end power and not able to hit the rev limiter unless pushed . 4th gear starts were easy off idle.

Right now we proved that this engine has 55hp in it with the stock cams at 108. Im either going to leave it at 108 with the new exhaust or try for even more peak hp by messing with the cam timing. Im shooting for 60 here. (long shot?) I figure the updating of the porting alone should yeild 56-57hp as all my 468's can do. Dyno tests showed the 460 to have at least 3-5 hp boost and great flow at 8000 plus rpm as shown by the dyno sheet. It just didnt want to stop pulling past where all other engines signed off. Now this engine is a 10cc bigger motor with bigger valves and a stroker crank. I need the engine to breath at high rpm to get that last few ponies out of it.
Just need to know if I should play it safe and let the exhaust cam do the work at 108 or try to retard one or the other even more trying to hunt down the 505 for peak hp. Ive literally got no info on what actually would be a best guess on cam lobe separation so its looking like I might just play it safe. Dont care in the slightest about drivabilty or power hits . Its all for the number.

claas900 · #7 Post by **claas900** » Sun Jan 28, 2007 5:29 pm

I know its not exlacty what your looking for but it might lead you to something? http://speedtalk.com/forum/viewtopic.php?t=450 Iv never searched the sight to see if they have anything else.

wistech · #8 Post by **wistech** » Sun Jan 28, 2007 5:40 pm

Thanks Great web site. already learned something new. Do not clean titanium parts with clorinated solvents like brake cleaner.

dalewannbe · #9 Post by **dalewannbe** » Sun Jan 28, 2007 5:54 pm

I think you and 27 and the rest of the hp hungry crazies should invest in a dyno. Then you may never leave garage.