Does this prove David Vizard's 128 lsa formula ?

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Yes, 128 was for SBC engines. What DV said that it worked well for other parallel valve heads & was better than guessing....

Much to much is being made of this by people trying to second guess what DV said or meant, rather than looking at the history of where 128 came from.
128 was the result of the cam selection software developed by DV [ & I believe Stan Weiss was involved ] & that he sells.
128 was designed to stop folks ringing a cam company & having the phone jockey look at the computer screen..& recommend a cam with a wide LSA.......that they have in stock....
You might call 128 an educated guess rather a wild guess.....
Sig Erson was another pioneer, ahead of the curve; he & DV worked together at some point & SE was a proponent of tight LSA...way back in the 1970s....

From Erson....

img295.jpg
 
RustyRatRod said:
What I wonder is, say you figure the formula based on your combo. Like mine comes out to be 108. Is that what you need set in stone or is that a MAXIMUM or MINIMUM LSA?
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Supposed to be optimal. To me should mean narrower or wider than calculated should lose torque, and it's generally accepted wider will, so to me loss in that direction isn't much proof of anything, tighter than calculated should also be shown to be a loss if the formula finds optimal.

I wouldn't have a problem if DV acted like it's a rule of thumb ball park etc.. But he sells it as it's gonna put you up there with the big boys and get 1.4+ lbs-ft per cid etc..
 
Bewy said:
Yes, 128 was for SBC engines. What DV said that it worked well for other parallel valve heads & was better than guessing....

Much to much is being made of this by people trying to second guess what DV said or meant, rather than looking at the history of where 128 came from.
128 was the result of the cam selection software developed by DV [ & I believe Stan Weiss was involved ] & that he sells.
128 was designed to stop folks ringing a cam company & having the phone jockey look at the computer screen..& recommend a cam with a wide LSA.......that they have in stock....
You might call 128 an educated guess rather a wild guess.....
Sig Erson was another pioneer, ahead of the curve; he & DV worked together at some point & SE was a proponent of tight LSA...way back in the 1970s....

From Erson....

View attachment 1716213337
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If he said it was for ball park guesstimation etc.. Thats one thing but He and everyone plays it up that it's gonna put you up there with the 1 percent of builders. I'm not even saying there's no merit to it just that those dyno graph to me didn't show really any proof that the formula works over say just picking to run tighter lsa.

Plus those dyno shootouts aren't a real test against or for, cause to do it right you first have to run a DV calculated cam and the other cams would all have the same overlap. But what those test are generally showing the tighter the lsa the more torque I'm sure if you kept going tighter the gains would be less and less and probably at some point start losing, but what was shown that tighter than what probably would of been recommended still gained and you'd have to run pretty wide to lose a big chunk of torque.

Is running a 110 lsa compared to 106-109 really setting you that far off the mark, is running a 106-109 gonna put you in the 1.40 lbs-ft club doubt it. Not say don't run tighter than 110 but act like you just gave up 50tq hasn't been proven yet.
 
128 for SBC
127 for ford Windsor
132 for BBC

DV stated this in one of his cam videos.
He also said 128 was close for SBM.
 

Does this prove David Vizard's 128 lsa formula ?​

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All it proves is how good he is at marketing himself and how gullible people will believe anything their told.

Do you really think his simple formula could predict how Combustion will take place in a cylinder......Considering some of the smartest minds in automotive engineering cannot even come up with complex calculations to do it.

Maybe all those guys in F1, Pro Stock, Indy and Nascar and other elite motorsports not to mention all those guys who work in Engine R&D for companies that spend BILLIONS developing engines should just watch this guys YouTube channel and they will discover the "Secrets" to making power because he did some dynos......
 
Hysteric said:
All it proves is how good he is at marketing himself and how gullible people will believe anything their told.

Do you really think his simple formula could predict how Combustion will take place in a cylinder......Considering some of the smartest minds in automotive engineering cannot even come up with complex calculations to do it.

Maybe all those guys in F1, Pro Stock, Indy and Nascar and other elite motorsports not to mention all those guys who work in Engine R&D for companies that spend BILLIONS developing engines should just watch this guys YouTube channel and they will discover the "Secrets" to making power because he did some dynos......
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That's funny, 'cause DV's '128' rule doesn't apply to a single one of those racing series You mentioned, not one. Maybe early '70's NAPCAR & down......
 
Killer6 said:
That's funny, 'cause DV's '128' rule doesn't apply to a single one of those racing series You mentioned, not one. Maybe early '70's NAPCAR & down......
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Are you saying that internal combustion engine science doesn't apply to what he builds?
 
Hysteric said:
Are you saying that internal combustion engine science doesn't apply to what he builds?
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Nope, I'm saying exactly what I meant. DV's formula was devised for modified factory SBC heads & similar, with adjustments to the formula already noted by another poster above, that's what I'm saying.
That also would be modified for cast exhaust mannys vs headers, restrictive exhaust vs open, etc.
If You plug that formula in, many of Mopar's PurpleShafts track pretty close to it, & I'm certain Shepard & Co. did enough R&D of their own.
 
i read a book from DV, got convinced regarding the LSA theory. Had comp grind me a camshaft with 108°LSA instead of the common 110° - bingo, new best ET by quite a bit. All of the tests with somewhat "limited" cylinder heads show gains when reducing the LSA up to a certain point. One day i´ll try a 106°LSA cam (that´s what the formula shows for my next combination).
 
Killer6 said:
If You plug that formula in, many of Mopar's PurpleShafts track pretty close to it, & I'm certain Shepard & Co. did enough R&D of their own.
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Can't beat 1960's camshaft tech in 2024.......Good to see DV has rediscovered the 1960's all over again for you guys.
 
junkyardhero said:
i can't believe i wasted 8min reading this...
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It wasn't wasted you learnt the biggest secret in 60 years in how to pick the most powerful cam for any and every combination with DV's secret formula......
 
Hysteric said:
Can't beat 1960's camshaft tech in 2024.......Good to see DV has rediscovered the 1960's all over again for you guys.
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I know, 'cause now We've got 'miracle lobes' for our '60's & '70's engines, right??
 
Killer6 said:
I know, 'cause now We've got 'miracle lobes' for our '60's & '70's engines, right??
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Perfect for our new aluminium heads with fast burn chambers.....and shitter fuel.

I'm sure that "Formula" works perfectly for every fuel and every chamber design too.....
 
RustyRatRod said:
Ok. Thanks. I get 108 for my slant 6. I thought 106 was it but I guess it's not.
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It also changes for every point under 10.5:1 compression.... i can't remember the change but someone will mention it...
 
RustyRatRod said:
Ok. Thanks. I get 108 for my slant 6. I thought 106 was it but I guess it's not.
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Here ya go.. had to go find it... I used his formula to pick my cam.... haven't fired it up yet but my entire build switched directions so i have such the wrong cam in my motor... It will run out at 5500 rpm and i have 4.57s now instead of the 2.89s that were in it.. it will be fun to 60 or so.. which is fine :) (i ended up using the formula getting 108lsa, i got a 109 cam due to wanting something off the shelf with the specs i wanted)
 
Icetech said:
It also changes for every point under 10.5:1 compression.... i can't remember the change but someone will mention it...
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My new engine will be dead on top of 10.5
 
@273 Did you read DV’s book(s)?

I think to many are over thinking this. DV spelled it out.
I also think your posted amount of power loss is a lot. But this may depend on the engine/head/etc combo and how good vs how bad a cam choice can be.
 
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273 said:
The examples he give shows mid torque gains with going with a tighter lsa but was that really even in question ?
But to me the gains aren't large enough to say it proves DV's formula, if anything it disproves it cause to me for the formula to be valid being a few degrees off of calculated lsa in either direction should have huge losses, I'd like to see engines that the formula predicts wider lsa like 114-116 + and run 108 lsa and less against them and see if there's loses or gains, would be a better tests.

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I watched this video months ago... something relaxing bout this guy just driving round talking bout cams....
 
I was having a really good laugh and conversation with Mike of B3. He also thought that everyone leaned on this formula to much. While I do agree with both DV and Mike, I see it as a situation dependent thing as to what the car owner is looking for.

I’ve run cams on a 112 before because I knew that it would idle smooth and pull vacuum which is what I was looking for. Not so much the “Massive Power” gains or losses. Just a certain characteristic..

I’ve used a MP flat oval track cam that was a 106 LSA. It had an idle like a lumberjack on crack withdrawal. It was an insane sounding cam. Being in a weekend toy, I did t care much. The cam had a narrow power band and when it was in it, holy cow did that engine pull!

I currently have a cam on a 108 LSA in my 10.5-1, 340 engine.
241@050 HFT W/about .550 lift. It has a snotty idle, just fine for the once in a while driving hot rod. Not an idle I’d use on a actual ride m driving everyday.
 
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