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Anonymous
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Does anyone know if a wide LSA or narrow (108-114?) gives a better part throttle responce in a 250 I6.
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Anonymous
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what is an LSA? my throttle response isnt that great and i have my stock motor set up for the best i can get so if this LSA thing will help then that would be cool.
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Anonymous
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The reality for me is that I usually cruise on very low rpms about 2200 rpm due to the speed limit of 80 kph on my journey to work. Im looking to maximise economy down low while still pushing higher rpm when I want it. From what Ive read a wider LSA helps with this I think, due in part due in to better part throttle responce? I was surprised to find that the gen 111 engines have about a 118 LSA.
I know there is some benefit with a narrower LSA at WOT. Trouble is no one Ive seen tests power at part throttle and this is where it may matter most.
I realise the questions a bit relative to duration, but a generisation would do. If anyones up to it?
I know there is some benefit with a narrower LSA at WOT. Trouble is no one Ive seen tests power at part throttle and this is where it may matter most.
I realise the questions a bit relative to duration, but a generisation would do. If anyones up to it?
These may help...
http://www.chevytalk.com/tech/101/Cam_Theory.html
http://www.webcamshafts.com/cam_glossary.html
To summarize: For max economy and low engine speed performance you will definitely want a wide LSA, and lobe profiles that emphasize lift instead of duration.
http://www.chevytalk.com/tech/101/Cam_Theory.html
http://www.webcamshafts.com/cam_glossary.html
To summarize: For max economy and low engine speed performance you will definitely want a wide LSA, and lobe profiles that emphasize lift instead of duration.
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Anonymous
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I put a couple of posts on here a couple of days ago does anyone know where they went???
i think more than few disapeared I tryed to get on here wed. night but it was a no go. I am missing a few myself.
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Anonymous
Guest
Re-posted couple of replies from Sam B at C.O.M.E engines on cam selection and LSAs.
You recommended the CLH 191.
Q1, Is the CLH 191 a dual pattern cam? The duration at 50 is 217/218 but the advertised says it has a 12 degree separation between the inlet and exhaust (278 290 I think).
Reply, Intake lobes are very often faster acting to open vale more quickly to fill cylinders.
Exhaust lobes don't need such fast opening rates as the inertia of
exhaust gases is incredibly powerful and better gas velocity is actually
achieved by opening slightly slower. Doesn't apply to all cases, depends
on port type.
Q2, Does a wider lobe separation angle ( such as this one has 114) with around this duration tend to give better economy than one with a shorter LSA?
Reply, Yes better economy potential but slightly less peak torque and longer spread of torque which is better for daily use.
Another reply on very wide LSA quiery?
EFI engines are different up to a point.
The 118 lca in a Gen 3 is actually closer to 120 degrees.
Reason, less low down torque to reduce transmission and diff breakages.
Better emissions.
More top end power, so the factory power figures look better.
Like any factory deal, it's a compromise trying to achieve a good
outcome in many areas.
Sam
You recommended the CLH 191.
Q1, Is the CLH 191 a dual pattern cam? The duration at 50 is 217/218 but the advertised says it has a 12 degree separation between the inlet and exhaust (278 290 I think).
Reply, Intake lobes are very often faster acting to open vale more quickly to fill cylinders.
Exhaust lobes don't need such fast opening rates as the inertia of
exhaust gases is incredibly powerful and better gas velocity is actually
achieved by opening slightly slower. Doesn't apply to all cases, depends
on port type.
Q2, Does a wider lobe separation angle ( such as this one has 114) with around this duration tend to give better economy than one with a shorter LSA?
Reply, Yes better economy potential but slightly less peak torque and longer spread of torque which is better for daily use.
Another reply on very wide LSA quiery?
EFI engines are different up to a point.
The 118 lca in a Gen 3 is actually closer to 120 degrees.
Reason, less low down torque to reduce transmission and diff breakages.
Better emissions.
More top end power, so the factory power figures look better.
Like any factory deal, it's a compromise trying to achieve a good
outcome in many areas.
Sam
