103 upgrade disappointing
Sponsor
Joined: Dec 2007
Posts: 12,084
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But if other avenues were to be pursued, even more low end torque can be established than that school bus cam, can even THINK of delivering, and still be able to rip, extremely hard, all the way to the rev limiter.
It all depends on what your looking for.
Scott
It all depends on what your looking for.
Scott
Road Captain
Joined: Aug 2009
Posts: 619
Likes: 3
From: In Garage
You've been reading too much! You can't look at LSA alone and make general statements about cam selections or the dyno results. There are too many other factors to consider in cam selection to isolate LSA as a critical criteria; gotta look at the total profile. Generally speaking, you will be hard pressed to find a cam with all the other crtiical specificationsn, i.e., intake valve close, duration, lift and TDC lift designed for a particular application with an LSA that doesn't also fit that particular application, so LSA, while important, is not a crtical selection criteria.
I have attached a dyno chart to make the point. This build uses one of the cams you site in your post as a cam that "is good for peak #s for a short period of time but quickly fizzles out." Please show me where this cam is peaking early or fizzling out.
Most Harley cams will hold their peak TQ for 1000rpms, so the decision is where do we want the peak, center left, center or center right. Much more to the criteria than LSA goes into that decision.
I have attached a dyno chart to make the point. This build uses one of the cams you site in your post as a cam that "is good for peak #s for a short period of time but quickly fizzles out." Please show me where this cam is peaking early or fizzling out.
Most Harley cams will hold their peak TQ for 1000rpms, so the decision is where do we want the peak, center left, center or center right. Much more to the criteria than LSA goes into that decision.
Could you please post the opening and closing points of the cam used in in that dyno? just curious.
HDF Community Team
Joined: Jun 2006
Posts: 12,778
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From: san antonio
Seriously, it doesn't matter. I just wanted to point out to others reading this thread that LSA is just one element of cam selection and not a critical criteria. If one gets the intake valve close, duration, and lift right to produce the desired results, chances are that the LSA will be right as well.
Stellar HDF Member
Joined: Apr 2005
Posts: 3,108
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From: Lincolnton, NC
Well I just got back from Doc's. I'll post the dyno charts tomorrow. Doc found the clutch was slipping. He also found the air cleaner was holding the engine back. So first thing he installed a heavy duty clutch spring, then a new SE air cleaner.
Thread Starter
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Advanced
Joined: Jun 2009
Posts: 79
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From: orlando, fl
I was running a K&N filter but it was 4 years old. Doc said it was holding the bike back and installed an SE filter. I was surprised because the K&N was supposed to be a high flow filter.
Elite HDF Member
Joined: Apr 2007
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From: Seattle, WA
It's the football ... need to replace it with a velocity stack ...! J/K
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From: The Internet (& Dyer, Indiana)
Cha-ching!
Road Captain
Joined: Aug 2009
Posts: 619
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From: In Garage
Oh, I thought maybe you could tell me what they were by reading the dyno chart.
Lol
Seriously, it doesn't matter. I just wanted to point out to others reading this thread that LSA is just one element of cam selection and not a critical criteria. If one gets the intake valve close, duration, and lift right to produce the desired results, chances are that the LSA will be right as well.
Lol
Seriously, it doesn't matter. I just wanted to point out to others reading this thread that LSA is just one element of cam selection and not a critical criteria. If one gets the intake valve close, duration, and lift right to produce the desired results, chances are that the LSA will be right as well.
For instance if you have a low flowing cylinder head u know you will need a tighter lobe separation. The overlap will help with cylinder fill.
Also something to think about is on a long stroke small bore combination (like the 96'' twin cam) long stroke has less room for valves, so it may have less breathing capabilites. So once again u will need a cam with tight lobe separation. Knowing this will give u a good base to work from. This is why woods cams work so well in stock twin cams they have a lsa of 101.