Does this prove David Vizard's 128 lsa formula ?

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Newbomb Turk said:
You didn't say 20% in your comments and I'm not interested in the video. Depending on what it is 20% is probably 2 or 3 percent low so now I'll ask how did they come up with 20%.

And remember I do not want to watch the whole video, which is why I asked in the first place.
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Here you go "Rat" >

It's all in the "comments and responses" from the above Sorta Stock 318 Dyno Pull video above.

I copy the video link then I go pull it up on the YouTube website, where I can read the comments. Interesting, there is good info to be had there.


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114? I hear he could gain 50-60hp just going down to like 108.....
 
Icetech said:
114? I hear he could gain 50-60hp just going down to like 108.....
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and tack on another 25 with a 750DP!

but whatever. dude needs to ditch the zero and get with the hero-- should be running a 5.9 and that'd be like 100~150 more ponies. no one denies this.
 
junkyardhero said:
and tack on another 25 with a 750DP!

but whatever. dude needs to ditch the zero and get with the hero-- should be running a 5.9 and that'd be like 100~150 more ponies. no one denies this.
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Or it could just be a driver car and he is happy with what he has :)
 
Don't forget about flipping the offset on those pistons.
 
Bodyperson said:
The difference for the caprice was compression ratio too. I can’t believe this isn’t a bigger part of this discussion. All of this discussion also seems like all out racing applications. It’s not. Sure, run the tight separation but dialing back your timing to run on pump gas is a power killer or don’t and kill power with detonation.
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I'd rather have the compression and roll some timing out IF I have to than to lower the compression so I can run a bunch of timing.
 
George Jets said:
Here you go "Rat" >

It's all in the "comments and responses" from the above Sorta Stock 318 Dyno Pull video above.

I copy the video link then I go pull it up on the YouTube website, where I can read the comments. Interesting, there is good info to be had there.


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Ok George, this is YOUR baby so I'll ask you. How did THEY come up with 20%? Pull it out of their ***? Did they do a coast down test? Consult the magic 8 ball? Did they conjure the Witch of Endor?

Like I said, 20% sounds at least a bit low.

This is what happens when you worship numbers without asking a simple question.
 
Newbomb Turk said:
I'd rather have the compression and roll some timing out IF I have to than to lower the compression so I can run a bunch of timing.
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I guess we are right back to trying more than one cam to see what the engine wants.
 
Newbomb Turk said:
I'd rather have the compression and roll some timing out IF I have to than to lower the compression so I can run a bunch of timing.
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How much timing would you be willing to lose ?
Eg.. total 32/30/28
 
Bodyperson said:
I guess we are right back to trying more than one cam to see what the engine wants.
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Yup. And that costs big money. That's why Vizard came up with the formula. It's certainly not a drag racing formula, but for what he likes to build it's better than calling a cam company and getting what they think.
 
Bodyperson said:
I guess we are right back to trying more than one cam to see what the engine wants.
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Why wouldn't you think you might have to try a couple of cams, gears, carbs etc.. To dial the powerband to suit you.
 
273 said:
How much timing would you be willing to lose ?
Eg.. total 32/30/28
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Depends on RPM. Most engines (Can't say EVERY engine because I haven't seen every engine from every era but...let's leave it there) want less timing at peak torque and more timing at peak power.

Where that peak power is will determine how much total you end up with. An engine with peak RPM at 6k won't have as much total as an engine peaking at 7500.

To that end, I'm not sure why being able to reduce timing is a bad thing. You want peak cylinder pressure by 14-18 degrees ATDC. If you have to fire the plug at 40 degrees BTDC you have pretty close to 35ish degrees of crank rotation where chamber pressure is working against making power.

If you can fire the plug on that same engine at say 30 BTDC you have now reduced that negative work by 10 degrees. Of course, that's as long as you still get peak cylinder done by 14-18 degrees ATDC.

Volumetric efficiency affects timing requirements. Not many people would argue that. So think about what a locked out or an all in curve by 2500 power does to power?

Not only are you increasing negative working pressure, all that timing is beating up parts.
 
I was always told 15%....
Dale Davies said:
By what reasoning? I do agree that more area under the curve could be picked up, but 50 - 60HP is a bit much I think. About half that would likely be closer.
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Jesus man.. it was a joke.... if you read back in this thread people actually believe that.

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Dale Davies said:
By what reasoning? I do agree that more area under the curve could be picked up, but 50 - 60HP is a bit much I think. About half that would likely be closer.
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So we've been in agreement this whole time :)
 
Newbomb Turk said:
Depends on RPM. Most engines (Can't say EVERY engine because I haven't seen every engine from every era but...let's leave it there) want less timing at peak torque and more timing at peak power.

Where that peak power is will determine how much total you end up with. An engine with peak RPM at 6k won't have as much total as an engine peaking at 7500.

To that end, I'm not sure why being able to reduce timing is a bad thing. You want peak cylinder pressure by 14-18 degrees ATDC. If you have to fire the plug at 40 degrees BTDC you have pretty close to 35ish degrees of crank rotation where chamber pressure is working against making power.

If you can fire the plug on that same engine at say 30 BTDC you have now reduced that negative work by 10 degrees. Of course, that's as long as you still get peak cylinder done by 14-18 degrees ATDC.

Volumetric efficiency affects timing requirements. Not many people would argue that. So think about what a locked out or an all in curve by 2500 power does to power?

Not only are you increasing negative working pressure, all that timing is beating up parts.
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I guess what I meant was there a limit how low you'd run total timing to gain more CR,
Say your 10.5:1 engine runs at 35, but to go 11.5:1, you got to run 32, and 12.5:1, 28 etc..
Is there a point where you'd stop? I get it ain't simple as that and there's a bunch of variables.
 
Newbomb Turk said:
Depends on RPM. Most engines (Can't say EVERY engine because I haven't seen every engine from every era but...let's leave it there) want less timing at peak torque and more timing at peak power.

Where that peak power is will determine how much total you end up with. An engine with peak RPM at 6k won't have as much total as an engine peaking at 7500.

To that end, I'm not sure why being able to reduce timing is a bad thing. You want peak cylinder pressure by 14-18 degrees ATDC. If you have to fire the plug at 40 degrees BTDC you have pretty close to 35ish degrees of crank rotation where chamber pressure is working against making power.

If you can fire the plug on that same engine at say 30 BTDC you have now reduced that negative work by 10 degrees. Of course, that's as long as you still get peak cylinder done by 14-18 degrees ATDC.

Volumetric efficiency affects timing requirements. Not many people would argue that. So think about what a locked out or an all in curve by 2500 power does to power?

Not only are you increasing negative working pressure, all that timing is beating up parts.
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No disagreement Turk. The situation is a matter of combustion efficiency beginning at the moment the spark takes place. A fraction of a second after ther spark occurs there is virtually no advance of the flame kernal as it establishes itself. Then slowly it begins to expand into the close molecules of air (O2) and fuel. There are still few molecules combusting yet, so heating of the cylinder charge is almost nonexistant. It takes 5° to 10° for the flame to expand to include much of the combustion chamber, so some heating but not yet a lot. At TDC most of the combustion chamber has flame in it, but combustion is not yet complete. That should be about 10° ATDC enabling maximum heating by around 15° ATDC. So yes there is some negative power producing pressure on the piston between the time of the spark and TDC. This is illustrated in DV's How to Build Horsepower book.
 
Bodyperson said:
I was just saying that we are getting away from the original discussions.
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That's ok I'm not a sticklier on my threads, I got all could get out of this thread which wasn't much :) It's free to take on a life of it's own now.
 
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