D V Live now.
Moderator: David Vizard
Re: D V Live now.
SchmidtMotorWorks wrote:
> [quote=digger post_id=928569 time=1667249333 user_id=6525]
> In fairness to DV I've only ever heard him say this "128" is for
> WOT performance (its a given in anycase) so those are moot points in the
> context
> [/quote]
>
> Wide open throttle or not, a cam design should be compatible wit the
> intended application, the typical DV book reader is working on street
> driven cars with a wide variety of exhaust and intake systems each changing
> the optimum LSA.
Last time i checked simply defining the LSA does not make a camshaft incompatible with a street engine. There is the ambiguous overlap portion of his method that will impact on these aspects such idle, part throttle, fuel economy etc
> [quote=digger post_id=928569 time=1667249333 user_id=6525]
> In fairness to DV I've only ever heard him say this "128" is for
> WOT performance (its a given in anycase) so those are moot points in the
> context
> [/quote]
>
> Wide open throttle or not, a cam design should be compatible wit the
> intended application, the typical DV book reader is working on street
> driven cars with a wide variety of exhaust and intake systems each changing
> the optimum LSA.
Last time i checked simply defining the LSA does not make a camshaft incompatible with a street engine. There is the ambiguous overlap portion of his method that will impact on these aspects such idle, part throttle, fuel economy etc
Re: D V Live now.
digger wrote:
There is the ambiguous overlap portion of his method that will
> impact on these aspects such idle, part throttle, fuel economy etc
Yer, that's almost a better starting point, pick the idle quality you need (could be for track rules) there's your overlap decided, then build out from there until you reach your desired rev range.
There is the ambiguous overlap portion of his method that will
> impact on these aspects such idle, part throttle, fuel economy etc
Yer, that's almost a better starting point, pick the idle quality you need (could be for track rules) there's your overlap decided, then build out from there until you reach your desired rev range.
Ignorance leads to confidence more often than knowledge does.
Nah, I'm not leaving myself out of the ignorant brigade....at times.
Nah, I'm not leaving myself out of the ignorant brigade....at times.
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Re: D V Live now.
For given durations and acceleration rates, LSA determines drivability.digger wrote: ↑Tue Nov 01, 2022 2:54 am SchmidtMotorWorks wrote:
>>
> Wide open throttle or not, a cam design should be compatible wit the
> intended application, the typical DV book reader is working on street
> driven cars with a wide variety of exhaust and intake systems each changing
> the optimum LSA.
Last time i checked simply defining the LSA does not make a camshaft incompatible with a street engine. There is the ambiguous overlap portion of his method that will impact on these aspects such idle, part throttle, fuel economy etc
DV said it is "the most important thing about spec'ing a cam"
The notion that 2 inputs determine the LSA (and that it is the most important thing about spec'ing a cam) is absurd.
The most important thing about spec'ing a cam is determining that it is compatible with the valve train.
Helping to Deliver the Promise of Flying Cars
Re: D V Live now.
Now this is a genuine question. Not some kind of bait so I'll ask the following:
The application is strictly drag racing. Drivability isn't so much a concern as is maximum output.
Overlap, duration, LSA, ICL, lift.
These are the elements of a cam spec as I understand them and how would you rate in order of importance?
The specifics of the profile itself, that is it's "intensity" can be part of another conversation if it can work that way.
I'm asking because I'd like to know more about it.
When I have another discussion with my cam guy, the better informed I am, the more satisfying the result might be.
Thanks in advance.
The application is strictly drag racing. Drivability isn't so much a concern as is maximum output.
Overlap, duration, LSA, ICL, lift.
These are the elements of a cam spec as I understand them and how would you rate in order of importance?
The specifics of the profile itself, that is it's "intensity" can be part of another conversation if it can work that way.
I'm asking because I'd like to know more about it.
When I have another discussion with my cam guy, the better informed I am, the more satisfying the result might be.
Thanks in advance.
Kevin
Re: D V Live now.
Just to clarify, I'm not asking for a spec as there isn't nearly enough info given.
Just some guidelines a guy could go by.
Just some guidelines a guy could go by.
Kevin
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Re: D V Live now.
Knowing what acceleration rate your valve train can handle is primary because it determines the area under the curve and the operation range.skinny z wrote: ↑Tue Nov 01, 2022 10:30 am Now this is a genuine question. Not some kind of bait so I'll ask the following:
The application is strictly drag racing. Drivability isn't so much a concern as is maximum output.
Overlap, duration, LSA, ICL, lift.
These are the elements of a cam spec as I understand them and how would you rate in order of importance?
The specifics of the profile itself, that is it's "intensity" can be part of another conversation if it can work that way.
I'm asking because I'd like to know more about it.
When I have another discussion with my cam guy, the better informed I am, the more satisfying the result might be.
Thanks in advance.
Once you know that you adjust the individual events to match the gas dynamics of the system.
Helping to Deliver the Promise of Flying Cars
Re: D V Live now.
That area under the curve would reference intensity then?
As in, seat numbers vs .050, .200, etc?
Fair enough. ( If I have that right).
That's something I wanted to talk about with Jones Cams.
I've a seat duration in mind for a hydraulic roller but I'm at a loss as to which of his profiles will live or die in this application.
Eg. 286 with 236@.050 or 286 with 224@.050.
As in, seat numbers vs .050, .200, etc?
Fair enough. ( If I have that right).
That's something I wanted to talk about with Jones Cams.
I've a seat duration in mind for a hydraulic roller but I'm at a loss as to which of his profiles will live or die in this application.
Eg. 286 with 236@.050 or 286 with 224@.050.
Kevin
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Re: D V Live now.
The area under the curve is computed by integration.skinny z wrote: ↑Tue Nov 01, 2022 10:40 am That area under the curve would reference intensity then?
As in, seat numbers vs .050, .200, etc?
Fair enough. ( If I have that right).
That's something I wanted to talk about with Jones Cams.
I've a seat duration in mind for a hydraulic roller but I'm at a loss as to which of his profiles will live or die in this application.
Eg. 286 with 236@.050 or 286 with 224@.050.
https://www.youtube.com/watch?v=FsC3do74UIo
Without expensive testing, your best path to know what your valvetrain can handle is to work with a cam designer (not a cam spec'er) that knows from experience.
Helping to Deliver the Promise of Flying Cars
Re: D V Live now.
SchmidtMotorWorks wrote:
> [quote=digger post_id=928634 time=1667285684 user_id=6525]
> SchmidtMotorWorks wrote:
> > [quote=digger post_id=928569 time=1667249333 user_id=6525]
> > In fairness to DV I've only ever heard him say this "128" is for
> > WOT performance (its a given in anycase) so those are moot points in the
> > context
> > [/quote]
> >
> > Wide open throttle or not, a cam design should be compatible wit the
> > intended application, the typical DV book reader is working on street
> > driven cars with a wide variety of exhaust and intake systems each changing
> > the optimum LSA.
>
> Last time i checked simply defining the LSA does not make a camshaft incompatible
> with a street engine. There is the ambiguous overlap portion of his method that will
> impact on these aspects such idle, part throttle, fuel economy etc
> [/quote]
>
> For given durations and acceleration rates, LSA determines drivability.
> DV said it is "the most important thing about spec'ing a cam"
> The notion that 2 inputs determine the LSA (and that it is the most important thing
> about spec'ing a cam) is absurd.
>
> The most important thing about spec'ing a cam is determining that it is compatible
> with the valve train.
The method proposed determines LSA and then an overlap number is chosen which gives duration. So it is not choosing a duration and putting it on the determined LSA. There is a very clear distinction.
The notion that it doesn’t consider more than WOT is actually completely wrong once you consider the second part of the method.
> [quote=digger post_id=928634 time=1667285684 user_id=6525]
> SchmidtMotorWorks wrote:
> > [quote=digger post_id=928569 time=1667249333 user_id=6525]
> > In fairness to DV I've only ever heard him say this "128" is for
> > WOT performance (its a given in anycase) so those are moot points in the
> > context
> > [/quote]
> >
> > Wide open throttle or not, a cam design should be compatible wit the
> > intended application, the typical DV book reader is working on street
> > driven cars with a wide variety of exhaust and intake systems each changing
> > the optimum LSA.
>
> Last time i checked simply defining the LSA does not make a camshaft incompatible
> with a street engine. There is the ambiguous overlap portion of his method that will
> impact on these aspects such idle, part throttle, fuel economy etc
> [/quote]
>
> For given durations and acceleration rates, LSA determines drivability.
> DV said it is "the most important thing about spec'ing a cam"
> The notion that 2 inputs determine the LSA (and that it is the most important thing
> about spec'ing a cam) is absurd.
>
> The most important thing about spec'ing a cam is determining that it is compatible
> with the valve train.
The method proposed determines LSA and then an overlap number is chosen which gives duration. So it is not choosing a duration and putting it on the determined LSA. There is a very clear distinction.
The notion that it doesn’t consider more than WOT is actually completely wrong once you consider the second part of the method.
Re: D V Live now.
FWIW:
DV states the following:
"There are 5 parameters to be addressed when selecting a cam for best performance.
In order of importance they are: overlap, lobe centreline angle (LCA/LSA), advance/retard setting, lift and duration."
The 128 rule is used to determine one parameter, that being the LSA, in a finite number of applications.
Make of it what you will.
DV states the following:
"There are 5 parameters to be addressed when selecting a cam for best performance.
In order of importance they are: overlap, lobe centreline angle (LCA/LSA), advance/retard setting, lift and duration."
The 128 rule is used to determine one parameter, that being the LSA, in a finite number of applications.
Make of it what you will.
Kevin
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- Vendor
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Re: D V Live now.
That isn't what he originally claimed.skinny z wrote: ↑Tue Nov 01, 2022 8:04 pm FWIW:
DV states the following:
"There are 5 parameters to be addressed when selecting a cam for best performance.
In order of importance they are: overlap, lobe centreline angle (LCA/LSA), advance/retard setting, lift and duration."
The 128 rule is used to determine one parameter, that being the LSA, in a finite number of applications.
Make of it what you will.
Helping to Deliver the Promise of Flying Cars
Re: D V Live now.
That was first published in 1999 in How to Build Max Performance SBC's on a Budget. The again in the 2nd edition published 2009.
My disclaimer: I'm not saying right or wrong. I'm just laying out some facts.
Now with this YouTube thing going on, there's so much information spilling out, I can't say I've bothered to keep up.
It's all quite different now.
My disclaimer: I'm not saying right or wrong. I'm just laying out some facts.
Now with this YouTube thing going on, there's so much information spilling out, I can't say I've bothered to keep up.
It's all quite different now.
Kevin
Re: D V Live now.
SchmidtMotorWorks wrote:
> [quote="skinny z" post_id=928688 time=1667347468 user_id=6881]
> FWIW:
>
> DV states the following:
> "There are 5 parameters to be addressed when selecting a cam for best
> performance.
> In order of importance they are: overlap, lobe centreline angle (LCA/LSA),
> advance/retard setting, lift and duration."
>
> The 128 rule is used to determine one parameter, that being the LSA, in a
> finite number of applications.
>
> Make of it what you will.
> [/quote]
>
> That isn't what he originally claimed.
definitely the journalist side came out in that early video (i.e. misleading headline statements). Definitely did not do himself any favours.
> [quote="skinny z" post_id=928688 time=1667347468 user_id=6881]
> FWIW:
>
> DV states the following:
> "There are 5 parameters to be addressed when selecting a cam for best
> performance.
> In order of importance they are: overlap, lobe centreline angle (LCA/LSA),
> advance/retard setting, lift and duration."
>
> The 128 rule is used to determine one parameter, that being the LSA, in a
> finite number of applications.
>
> Make of it what you will.
> [/quote]
>
> That isn't what he originally claimed.
definitely the journalist side came out in that early video (i.e. misleading headline statements). Definitely did not do himself any favours.
Re: D V Live now.
What video are you referring to?
It could be a full time job keeping track and I'd rather not.
On a similar note, one of DV's cohorts has a channel now and he was recently extolling the virtues of a tighter LSA.
I watched until his 3 cam test proved flawed enough for me to bail.
It could be a full time job keeping track and I'd rather not.
On a similar note, one of DV's cohorts has a channel now and he was recently extolling the virtues of a tighter LSA.
I watched until his 3 cam test proved flawed enough for me to bail.
Kevin