Does this prove David Vizard's 128 lsa formula ?

[Bewy]

It is funny. While I see lots of people taking pot shots at the 128 rule, which determines the LSA, I have yet to see anybody prove that it doesn't work: by grinding a cam using 128 & then using cams with identical parameters except for LSA....& dyno testing/comparing them.
The problem is that the LSA is just seen by many as a number. It is just a number, right?
It is much more than that....
It tells you in crank degrees where max lift occurs. For a 106 LSA, it tells you that the intake valve is at max lift at 106* ATDC & the exh valve at max lift 106* BTDC. Max lift, & either side of it, has to be an important parameter, especially for the intake side, because that is where maximum airflow happens. No air in = no hp.
The other important parameter is piston speed...& that is related to crank position ...which is tied in with LSA. More piston speed, more air 'pulled' into the chamber, all else being equal.

 

[Bewy]

128 rule & the Hemi? DV has repeatedly stated that the 128 rule works for parallel valve heads with a 9 -10.5 CR. Better breathing heads like the 351C, BB Chev, Hemi, etc need to be bigger than 128. I believe he quotes 131.5 for the BB Chev. Similarly if CR is increased the 128 needs to be bigger.

 

[273]

It is funny. While I see lots of people taking pot shots at the 128 rule, which determines the LSA, I have yet to see anybody prove that it doesn't work: by grinding a cam using 128 & then using cams with identical parameters except for LSA....& dyno testing/comparing them.
The problem is that the LSA is just seen by many as a number. It is just a number, right?
It is much more than that....
It tells you in crank degrees where max lift occurs. For a 106 LSA, it tells you that the intake valve is at max lift at 106* ATDC & the exh valve at max lift 106* BTDC. Max lift, & either side of it, has to be an important parameter, especially for the intake side, because that is where maximum airflow happens. No air in = no hp.
The other important parameter is piston speed...& that is related to crank position ...which is tied in with LSA. More piston speed, more air 'pulled' into the chamber, all else being equal.

It's shouldn't be up to others to prove DV right or wrong, he made the claims he should provide the proof apparently he has done 10's of thousands dyno runs, he apparently has done more than just about everyone else (his claim) should be able to provide 100/1000's of examples.

I'm not a DV hater, not even saying he wrong just haven't see any real proof, but I would like to see some test designed to put his formula to the test.

Maybe Eric's cam shootout will give us a glimpse.

 

[Bewy]

273,
I don't know how many examples you need. Watch the Cattle Dog video again. DV has dyno examples in his books & also in tests done for magazine articles. He has consistently said that cams are generally being ground on LSAs that are too wide.
I would say Jon Kaase took his advice, winning the EMC with a cam that had a 98* LSA, 92* ICL. I suspect what made DV think/look at tighter LSAs was the Morris Mini engine, with which he has had a lot of experience. Even the stock low performance cam for those was on 107.5* LSA, & performance versions were even tighter. Those little engines punched above their weight...
Below is a test that was done loooooooooooong before 128 came to be a conversation piece, identical cams, 106,108,110 LSA tested.

 

[273]

273,
I don't know how many examples you need. Watch the Cattle Dog video again. DV has dyno examples in his books & also in tests done for magazine articles. He has consistently said that cams are generally being ground on LSAs that are too wide.
I would say Jon Kaase took his advice, winning the EMC with a cam that had a 98* LSA, 92* ICL. I suspect what made DV think/look at tighter LSAs was the Morris Mini engine, with which he has had a lot of experience. Even the stock low performance cam for those was on 107.5* LSA, & performance versions were even tighter. Those little engines punched above their weight...
Below is a test that was done loooooooooooong before 128 came to be a conversation piece, identical cams, 106,108,110 LSA tested.

View attachment 1716308523

Narrower LSA generally makes more mid range torque, no one in the world is arguing that it doesn't, how does that prove DV's claims that his formula always gives the optimal lsa #, and gonna get huge gains over off the shelf cams and be like him the 1%er of top builders and pick cams that get around 1.4+ lbs-ft per cid. And that narrowing the LSA while maintaining same overlap is gonna be even better gains. That's the proof I'm looking for the ones that prove those claims.

All those test prove that tightening the lsa makes more midrange torque and again who's really arguing it don't. It's like saying more duration generally gains hp, no ****.

 

[Dan the man]

273,
I don't know how many examples you need. Watch the Cattle Dog video again. DV has dyno examples in his books & also in tests done for magazine articles. He has consistently said that cams are generally being ground on LSAs that are too wide.
I would say Jon Kaase took his advice, winning the EMC with a cam that had a 98* LSA, 92* ICL. I suspect what made DV think/look at tighter LSAs was the Morris Mini engine, with which he has had a lot of experience. Even the stock low performance cam for those was on 107.5* LSA, & performance versions were even tighter. Those little engines punched above their weight...
Below is a test that was done loooooooooooong before 128 came to be a conversation piece, identical cams, 106,108,110 LSA tested.

View attachment 1716308523

I've read on this website and other places as well that a tighter LSA improves the low to midrange torque, so say a cam has a 108* LSA and duration of 204* / 214* would the idle be smooth, noticeable or rough? I'm just asking.

 

[273]

I've read on this website and other places as well that a tighter LSA improves the low to midrange torque, so say a cam has a 108* LSA and duration of 204* / 214* would the idle be smooth, noticeable or rough? I'm just asking.

Haven't seen your name pop up in while.

It's the overlap mainly responsible for idle, overlap is duration and lsa, a 204°/214° cam isn't gonna have huge overlap even with a 108 lsa.

 

[Newbomb Turk]

It is funny. While I see lots of people taking pot shots at the 128 rule, which determines the LSA, I have yet to see anybody prove that it doesn't work: by grinding a cam using 128 & then using cams with identical parameters except for LSA....& dyno testing/comparing them.
The problem is that the LSA is just seen by many as a number. It is just a number, right?
It is much more than that....
It tells you in crank degrees where max lift occurs. For a 106 LSA, it tells you that the intake valve is at max lift at 106* ATDC & the exh valve at max lift 106* BTDC. Max lift, & either side of it, has to be an important parameter, especially for the intake side, because that is where maximum airflow happens. No air in = no hp.
The other important parameter is piston speed...& that is related to crank position ...which is tied in with LSA. More piston speed, more air 'pulled' into the chamber, all else being equal.

You pay for the cam and dyno time and I’ll test it.

But I’m not taking one cent out of my pocket to do it.

 

[273]

You pay for the cam and dyno time and I’ll test it.

But I’m not taking one cent out of my pocket to do it.

To me the only way to test it is say DV say a 260° @ 0.050" on a 107 lsa with 75 overlap is the cam for whatever build, someone would need to test it with cams probably at least from 102-112 lsa in 1 degree increments while maintaining the 75 overlap (of whatever it works out to be in the made up cam above).
And really you would need to do similar test with at least a dozen or so different type, sizes and levels of engine builds to see if it holds up overall.

All the test people are talking about just prove tighter lsa generally gains mid range torque.

 

[RustyRatRod]

It's shouldn't be up to others to prove DV right or wrong, he made the claims he should provide the proof apparently he has done 10's of thousands dyno runs, he apparently has done more than just about everyone else (his claim) should be able to provide 100/1000's of examples.

I'm not a DV hater, not even saying he wrong just haven't see any real proof, but I would like to see some test designed to put his formula to the test.

Maybe Eric's cam shootout will give us a glimpse.

All I've ever read he's actually DONE is raced a few Pinto motors. Or was it Vega? Gremlin?

 

[273]

All I've ever read he's actually DONE is raced a few Pinto motors. Or was it Vega? Gremlin?

Think he's raced Mini's.

I think his books are a good first step, overall if you follow his advice you generally gonna have decent results, problem is some take it as the final word in performance theory.

 

[RustyRatRod]

Think he's raced Mini's.

I think his books are a good first step, overall if you follow his advice you generally gonna have decent results, problem is some take it as the final word in performance theory.

I don't knock his knowledge. At ALL. ....and I'm not taking pot shots. I'm just not suckin his balls. I know how to design and build an engine and I know how to tune. That's all I really need. My own mind is a dangerous enough place for me. I don't need to get into someone else's.

 

[RustyRatRod]

Oh and his "128 rule" works out to a 108 LSA for any of my slant six builds. That's what I would choose anyway.....either that or a 106. So even without him, I was right. Funny how that works.