the DV Live Now post

[skinny z]

Interestingly, DV makes several references to Mike Jones...This brings to mind our earlier discussions (I'm referring to you Jon). Seems that between the two of you, this is a solid endorsement.
Thanks again.

[SchmidtMotorWorks]

Interestingly, DV makes several references to Mike Jones...This brings to mind our earlier discussions (I'm referring to you Jon). Seems that between the two of you, this is a solid endorsement.
Thanks again.

Yes of course, a cam picker has so much less information to draw from than a cam designer.

[SchmidtMotorWorks]

It appears we may have been responding simultaneously.
I've attached my text regardless although the closing line is only emphasized by your reply.
Thanks.

Found the reference to the .7 CoD.

From this we can say that the LCA = 128 - (CID/# of Cylinders/In Valve dia. in inches x 0.91). Putting some numbers into that we have for say a 355 inch SB Chevy that the required LCA =128- (355/8/2.02 X .91) which equals 108 degrees. So how accurate does that work out to be? Compare it to the graph a couple of posts ago – 108 is virtually spot on and so it will be for any parallel valve pushrod motor such as the SBC or similar (i.e. SB Ford & Chrysler) that has a CR around 10/1 and valve CD in the region of 0.7 (which most 3 angle valve jobs do).

If the intake valve has better than 0.7 CD average over the first 0.100 to 0.200 valve lift that 128 figure will increase and could go as high as 131 but only if the seats are really trick. If of course they are not and the CD is worse - then the key number could drop as low as 125.

Anyway, I'm genuinely hoping that DV steps in here.
Mr Schmidt has some very valid points to cover.

Chamber design is only one of many considerations for cam events.
The extraordinary focus on that is bizarre.

[David Vizard]

No disrespect here, but rather than telling us how good you are i would have thought the best way to prove something was with a comprehensive set of undisputable test data that supports your position.

Just how manytimes do I have to show my worth???????
You know I might just have other things to research rather than keep looking at what is water under the bridge!!!!
DV

[digger]

David Vizard wrote:
> [quote=digger post_id=929787 time=1668373909 user_id=6525]
> No disrespect here, but rather than telling us how good you are i would
> have thought the best way to prove something was with a comprehensive set
> of undisputable test data that supports your position.
> [/quote]
>
> Just how manytimes do I have to show my worth???????
> You know I might just have other things to research rather than keep
> looking at what is water under the bridge!!!!
> DV

Hi David, Youve done at least a couple videos on the critics of the 128 method. I’m not a non believer as there are some notable useful trends involved but you aren’t going to change any of the critics minds without hard scientific data

[skinny z]

digger wrote:
>
> Hi David, Youve done at least a couple videos on the critics of the 128 method. I’m
> not a non believer as there are some notable useful trends involved but you aren’t
> going to change any of the critics minds without hard scientific data

As a curious onlooker digger, what kind of "hard scientific data" would be suitable?

[digger]

skinny z wrote:
> digger wrote:
> >
> > Hi David, Youve done at least a couple videos on the critics of the 128 method.
> I’m
> > not a non believer as there are some notable useful trends involved but you
> aren’t
> > going to change any of the critics minds without hard scientific data
>
> As a curious onlooker digger, what kind of "hard scientific data" would be
> suitable?

Lets limit ourselves to street type engines which is kind of what the 128 is really intended.

So for a given engine when you choose Lobe A (say 220 @ 0.050") it makes best "power" (peak, average, weighted or whatever you define) at the LSA as determined by 128 method. You would need the lobes on multiple LSA and test each at difference advance/retard.

Then when you replace the lobe and use lobe B (say 230 @ 0.050" same lobe family) and repeat to see if it it still likes the same LSA

Then you use Lobe C (say 240 @ 0.050" same lobe family) etc and see if it still likes the same LSA

that's a lot of tests but if you've tested thousands of cams surely this has been done. Btw this can easily be done with a sim.

This would go along way to show that its the centrelines that are important not individual events.

The purists will say that each cam needs a different port, manifold, header to be optimised but you have to start somewhere and that's not how street engines are conceived in most cases.

[skinny z]

I think you said it best digger:

"that's a lot of tests but if you've tested thousands of cams surely this has been done".

I believe that would be the retort.

That said, and FWIW, if the 128 is reduced to it's basic components, that being a 10.5:1 SBC with a 2.02" intake valve (for an average CoD) and the objective is maximum torque within the confines of the port flow, (yes, a narrow window) then the cam that was recently spec'd to me, for a drag racing application also was predicted by DV's Torque Master program. Which as I understand it, has the 128 formula at it's core.
Seems to me I've said this before.

Now all of the above is to play into DV's post regarding his skeptics and all of his processes.
But, it also appears, that DV has left the building.

[digger]

skinny z wrote:
> I think you said it best digger:
>
> "that's a lot of tests but if you've tested thousands of cams surely
> this has been done".
>
> I believe that would be the retort.
>
> That said, and FWIW, if the 128 is reduced to it's basic components, that
> being a 10.5:1 SBC with a 2.02" intake valve (for an average CoD) and
> the objective is maximum torque within the confines of the port flow, (yes,
> a narrow window) then the cam that was recently spec'd to me, for a drag
> racing application also was predicted by DV's Torque Master program. Which
> as I understand it, has the 128 formula at it's core.
> Seems to me I've said this before.
>
> Now all of the above is to play into DV's post regarding his skeptics and
> all of his processes.
> But, it also appears, that DV has left the building.

If it has been done hence why I say the data/proof should be able to be provided (at least some of it to show that). Very little data has been provided and what has been didn’t really support some of the claims.

[GARY C]

SchmidtMotorWorks wrote:
> David, none of what you posted validates your 128 gimmick.
>
> The fact that the following variables influence the ideal LSA, and that
> your 128 formula does not take them as input, is all one needs to know to
> understand that the 128 formula is not comprehensive.
>
> Throttle size
> Intake manifold
> Port flow maps
> Chamber flow trajectory
> Intended RPM range
> Valvetrain stiffness
> Valvetrain mass
> Valve acceleration
> Header diameter, steps, collector dimensions
> Exhaust system
> Drivability requirements
> Emissions requirements
Oddly enough I believe at least 4 EMC Winning engines fit the 128 profile... Who else offers a simple way to select a cam that fits a winning EMC engine much less more than one?
I would love to see someone else put forth a simple math equation for the average guy to use to select his own cam.

[CamKing]

Oddly enough I believe at least 4 EMC Winning engines fit the 128 profile...

That is 100% meaningless.
The winning EMC cams were not chosen because of "128". "128" was not used in their design.
How many EMC winners don't fit the "128" rule of thumb?

If I came up with an "equation" for LSA that was "LSA= number of cylinders + 100", i could claim the 100,000+ wins of V8's running 108 LSA, as proof my "Equation" was accurate. Unfortunately, that's not how math works.

[skinny z]

What's kind of interesting in this latest EMC and EMC rebuttal is that if I understand it correctly, the 128 "formula" came about from innumerable dyno tests. That is, for a "given combination", (and we've seen that combination is very specific in the grand scheme of things), greater output, (in this case torque) was seen with "x" LSA.
In other words, the results came before the math.

With regards to the EMC results, it could probably be argued the same way. Take the results and find those which suit the formula.
As it was inferred earlier, how many other hundreds of EMC results fall outside? There were bound to be some that fall within.
Perhaps Gary C can find which participants fit that bill and reverse engineer which formula parameters are in play. It may well be that some of those specific entries are outside of the scope of 128 and yet have the LSA that might otherwise be suggested.

FTR, I don't rely on or propose anyone else rely on 128 as there's just too much going on as has been ably explained above by Mr. S.
I backed that up by having my new cam specced by a professional.
That my new 10.2:1, 2.02" valved SBC has a 108 LSA is not because of some rule or formula, but because it was scienced out.
But looking at it from the other perspective, 128 also suggested the same. But that part's not rocket science. This engine just fits the bill. A narrow bill at that.

No disrespect to DV intended. Torque Master was a lot of fun while it lasted.

[vannik]

There seems to be a major amount of misunderstanding of the 128 rule. Maybe we should firstly state some concepts and issues in a different way.

David Vizard has a large database of tested results for a large number of engines and component combinations. He took a selection of these results and used probably his engineering background and practical knowledge to fit a semi-empirical curve to this data and called it the 128 rule. This is not something voodoo or black magic but something regularly done in engineering. For many years this was how we designed aircraft. In my opinion the only mistake made was in not clearly defining how the 128 equation was derived in clear engineering terminology but the target audience was never meant to be a group of engineers.

In the last 15 or 20 years the more rigid mathematical treatment of large databases has grown dramatically and what would be really interesting is to see what such a treatment of this database will show. They can actually determine the physics behind the data. I think rather knocking what we have here is we should encourage DV to find such an expert to process his database and see what additional insights and knowledge can be obtained from this database.

[skinny z]

Well stated.

[SchmidtMotorWorks]

The problem is that the era that the testing was supposedly done is irrelevant to modern parts.
Not to mention the testing claimed does not add up.