LSA Question

[Mean416]

I don't think LSA comes down to some formula "discovered" by Vizard. Vizard has become a snake oil salesman, tarnishing his legacy with crap like the "128" formula.

Correlation is not the same as causation.

 

[273]

I don't think LSA comes down to some formula "discovered" by Vizard. Vizard has become a snake oil salesman, tarnishing his legacy with crap like the "128" formula.

I don't know if I 100% agree with that (snake oil salesmen), it's quite possible though, I'd like to see people independently prove/disprove his formula, but I feel it has one major flaw it based on valve size there's a lot of vastly different performing heads with eg.. A 2.02" valve it's hard to believe they all would need the same lsa.

Correlation is not the same as causation.

100% true.

 

[AJ/FormS]

My intended goal is to have good throttle response and low to midrange torque. As some have said that I maybe satisfied with the way it already is and if so then I'll concentrate on the tuning of the ignition and carburetor. I'm looking forward to the learning curve

For a snappy throttle response, you can't beat a great combo, high cylinder pressure, and a sharp tune.

For most of us with SBMs, street cams are gonna fall into a small range of about 210 to 230/235 range, because after that, the rpm of peak power is gonna get expensive to build reliability into, and cylinder pressure is getting harder and harder to find, cheaply.. So yur looking at about a 3>4-size cam range.
Now;
You just can't stick any of those 3>4 sizes into the same short block, expecting a power increase at the top, to not negatively affect low-rpm and throttle response. And if you start mixing cam brands between the sizes, yur just looking for heartaches.

I'm gonna try to save you weeks of time by the following few statements;
1) choose your heads first, and Lordy let them be closed chambers. But if not, then whittle the quench into line.
2) choose you cam size , to support your intended usage.
...If you intend to go racing, go get a race cam.
...If you want to idle along in parades, get a parade cam
...If you are gonna spend 90% of your time in town, get a town-cam
... If you need to drive the thing on the hiway, criminy 45 hp will get any tank A-body to 65 mph! so forget about power at 5500rpm.
... if you need a lil of this and that, pic the smallest cam that will do the job
3) run the Cylinder Pressure up to the max for the fuel that you can afford, and tune it!
4) Make sure the beast gets oil, lots and lots of oil. Put an extra capacity oilpan on it, with baffles if you like to drive like me. Oil the crap out of it; on the street you don't care about a few couple of hp lost to the pump. Yur never gonna know it!
5) if an automatic, stall it right.
The bigger the cam, usually the higher the stall
the lower the cylinder pressure, the higher the stall
If you don't stall it right, yur just gonna be frustrated beyond thinking straight.
6) gear it right. If the tires don't spin in Second Gear, it better be geared right or it's gonna be slow until it hits the cam........ again.
If the cam is too big, and the gear is too small, it's gonna powerpeak at an mph that you cannot legally drive at! Where is the advantage in that?
7) To have a snappy combo, you gotta be financially prepared to marry all the pieces of the combo, and your stated usage has got to drive every decision you make.
If your usage calls for a 210 can, then don't buy a 220 nor a 235. I guarantee that you'll be sorry.
If burning rubber to 50 mph, is on the agenda, together with snappy take off, choose the biggest SBM there is.
If hiway fuel economy is a factor, together with a snappy bottom end, then choose more cubes over a bigger cam
If fuel economy is a really really Big factor get a smaller engine. Marry the combo to the usage.
If you need an overdrive to cover all your bases, either get one, or change your stated usage.
8) if you have a financially challenged combo, then start with the stall and gears. I can't tell you how many guys will say, "I can't believe the difference 4.10s and a 2800 stall made to my stock318! I'm not suggesting BTW that you rush out and get some 4.10s....... lol

Man I was just gonna quickly dash off a couple of things, sheesh, here I am again, an hour later.

 

[TT5.9mag]

And remember, it’s a camshaft for Christ sakes. If you don’t like it, buy another one and some gaskets and change it. It only takes a few hours work.

 

[TT5.9mag]

I don't think LSA comes down to some formula "discovered" by Vizard. Vizard has become a snake oil salesman, tarnishing his legacy with crap like the "128" formula.

Correlation is not the same as causation.

Vizards 128 formula takes into account basically one thing, average torque production on a dyno. That’s what I don’t like about it. Unfortunately in the real world we have so many other variables to take into consideration (fuel mileage, idle quality, off idle drivability, vacuum for power brakes, just to name a few) that must also be considered.

 

[Dan the man]

For a snappy throttle response, you can't beat a great combo, high cylinder pressure, and a sharp tune.

For most of us with SBMs, street cams are gonna fall into a small range of about 210 to 230/235 range, because after that, the rpm of peak power is gonna get expensive to build reliability into, and cylinder pressure is getting harder and harder to find, cheaply.. So yur looking at about a 3>4-size cam range.
Now;
You just can't stick any of those 3>4 sizes into the same short block, expecting a power increase at the top, to not negatively affect low-rpm and throttle response. And if you start mixing cam brands between the sizes, yur just looking for heartaches.

I'm gonna try to save you weeks of time by the following few statements;
1) choose your heads first, and Lordy let them be closed chambers. But if not, then whittle the quench into line.
2) choose you cam size , to support your intended usage.
...If you intend to go racing, go get a race cam.
...If you want to idle along in parades, get a parade cam
...If you are gonna spend 90% of your time in town, get a town-cam
... If you need to drive the thing on the hiway, criminy 45 hp will get any tank A-body to 65 mph! so forget about power at 5500rpm.
... if you need a lil of this and that, pic the smallest cam that will do the job
3) run the Cylinder Pressure up to the max for the fuel that you can afford, and tune it!
4) Make sure the beast gets oil, lots and lots of oil. Put an extra capacity oilpan on it, with baffles if you like to drive like me. Oil the crap out of it; on the street you don't care about a few couple of hp lost to the pump. Yur never gonna know it!
5) if an automatic, stall it right.
The bigger the cam, usually the higher the stall
the lower the cylinder pressure, the higher the stall
If you don't stall it right, yur just gonna be frustrated beyond thinking straight.
6) gear it right. If the tires don't spin in Second Gear, it better be geared right or it's gonna be slow until it hits the cam........ again.
If the cam is too big, and the gear is too small, it's gonna powerpeak at an mph that you cannot legally drive at! Where is the advantage in that?
7) To have a snappy combo, you gotta be financially prepared to marry all the pieces of the combo, and your stated usage has got to drive every decision you make.
If your usage calls for a 210 can, then don't buy a 220 nor a 235. I guarantee that you'll be sorry.
If burning rubber to 50 mph, is on the agenda, together with snappy take off, choose the biggest SBM there is.
If hiway fuel economy is a factor, together with a snappy bottom end, then choose more cubes over a bigger cam
If fuel economy is a really really Big factor get a smaller engine. Marry the combo to the usage.
If you need an overdrive to cover all your bases, either get one, or change your stated usage.
8) if you have a financially challenged combo, then start with the stall and gears. I can't tell you how many guys will say, "I can't believe the difference 4.10s and a 2800 stall made to my stock318! I'm not suggesting BTW that you rush out and get some 4.10s....... lol

Man I was just gonna quickly dash off a couple of things, sheesh, here I am again, an hour later.

But I thank you for taking the time to explain this to me

 

[AJ/FormS]

But I thank you for taking the time to explain this to me

And remember, it’s a camshaft for Christ sakes. If you don’t like it, buy another one and some gaskets and change it. It only takes a few hours work.

To that end, I'd like to add this;
if you build with the thought that your cam might not be the exact one you want, then set the short block up in such a manner that you can go up or more likely down one size, and by changing gasket thickness, and or fuel octane, still have the Quench remain in the favored window, so as not to accidentally initiate a physical problem in the chamber, that could lead to engine damage.
This takes quite a bit of forethought with Iron heads, but it's not too bad with alloys; which, in my combo at least, were able to run up close to 200 psi; and Lordy that combo had bottom end and throttle response!

 

[Bewy]

Mean 416,
Where is your dyno testing [ or anyone else's ] that disproves the 128 rule????????????

 

[Bewy]

273,
I read a lot of your posts & see that you are a thoughtful person. Better than the idiots who get on here & other forums & dump on DV...yet have never done any dyno testing to check out the 128 rule.
Have a look at the Cattle Dog Garage video of 33 min that tested the 128 rule. DV did his own testing....19,200 dyno pulls.

Why do people use roller cams? One reason is that they can have more lift & duration than a FT cam. So how far the valve is open, & when is it fully open would seem to me to be veeeery important. Particularly the intake valve. I doubt you would want the intake valve at max lift [ for max hp at 5* ATDC when the piston is hardly moving & not generating any useful airflow.
But you would want the valve fully open at or close to max lift when piston speed is very high & generating a high vacuum to pull as much air into the cyl while the valve is in the max open position...& make as much HP as possible. Perhaps 108 ATDC?. Bingo, a cam with 108 LSA......which has the int valve at max open 108 ATDC & the exh valve at 108 BTDC.

I would

 

[273]

273,
I read a lot of your posts & see that you are a thoughtful person. Better than the idiots who get on here & other forums & dump on DV...yet have never done any dyno testing to check out the 128 rule.
Have a look at the Cattle Dog Garage video of 33 min that tested the 128 rule. DV did his own testing....19,200 dyno pulls.

I got most of DV books, my 1st and main one I got when was fairly young was Performance and economy which I've probably read a 100+ times, I'm sure that book has influenced how I see performance drivetrain should function. But I've seen very little of dyno/other evidence to back up from him and others to prove his points so I have to take with a grain of salt. But what's good about his books/teaching he practically the only one given the less informed a complete in depth system on the engine/drivetrain for people to use as a basis of understanding. Even if he's not a 100% accurate you could do a lot worse not going with his advice.

 

[Hysteric]

Go to Don Terrell's Speed Talk and read the conversations with Mike Jones (Cam Master) and David Vizard and study the 128 cam formula.

I agree with going to SpeedTalk and reading anything Mike Jones aka "Camking" has written but also UDHarold. Those 2 guys grind cams for the very pointing end of competition. (UDHarold passed a while ago)

I personally wouldn't bother with David Vizard.

For carb tuning go here:

Read Only unofficial Tuner and shrinker archive

 

[Mean416]

Mean 416,
Where is your dyno testing [ or anyone else's ] that disproves the 128 rule????????????

I've done a bit of dyno testing myself. Been a very long time. That doesn't have anything to do with the "128 rule".
DV is a living legend. All credit where it's due. But his YouTube stuff is snake oil. "FREE" and "BUDGET" and "LOW DOLLAR" verbiage thrown about in thumbnails, where he then goes on to talk about crap like ultra light cranks and exotic head porting. It's all over his channel. It destroys his credibility.

And the 128 rule. As well as other things he puts out there, are misleading guys into thinking they're making informed decisions.

 

[Newbomb Turk]

I've done a bit of dyno testing myself. Been a very long time. That doesn't have anything to do with the "128 rule".
DV is a living legend. All credit where it's due. But his YouTube stuff is snake oil. "FREE" and "BUDGET" and "LOW DOLLAR" verbiage thrown about in thumbnails, where he then goes on to talk about crap like ultra light cranks and exotic head porting. It's all over his channel. It destroys his credibility.

And the 128 rule. As well as other things he puts out there, are misleading guys into thinking they're making informed decisions.

So you have never tested the 128 rule? I can tell you that I use his 128 rule most of the time because it’s a quick way to get very close on LSA. Way closer than what most end up with.

And coincidentally I have another, much longer formula that requires me to use a scientific notation calculator and the two are usually within a degree of each other.

If you have the P/V without huge valve pockets then I always err on the side of a tighter LSA.

 

[furrystump]

I know practically nothing about cams, but I do know exhaust manifolds like a wider separation angle. I’m at 112 degs.

 

[Newbomb Turk]

I know practically nothing about cams, but I do know exhaust manifolds like a wider separation angle. I’m at 112 degs.

If it likes 112 it may want it wider still. Exhaust manifolds don’t do anything for overlap. Adding overlap just makes them dirty.

 

[TT5.9mag]

I know practically nothing about cams, but I do know exhaust manifolds like a wider separation angle. I’m at 112 degs.

A perfect example of a variable that needs consideration when selecting a camshaft profile, and one the 128 rule does not ever mention.

 

[furrystump]

It might, I plan on blackmailing Brian for the cam specs in the Butterscotch duster when I go roller.

 

[Newbomb Turk]

A perfect example of a variable that needs consideration when selecting a camshaft profile, and one the 128 rule does not ever mention.

True. But that particular formula (and the other one I use) we never developed to be used with exhaust manifolds.

I don’t care what it is, there are limits to math. Used correctly, the 128 formula will get you miles closer to the correct LSA than you will get by calling ANY cam grinder.

And just for clarity, the formula doesn’t assume you need to run power brakes. Or that the end user can tune.

 

[Garrett Ellison]

Yeah, I kinda figured this thread would be fairly polarizing once bringing up the 128 rule. It is true that D.V.s videos are teasers in order to get viewers to attend his performance seminars for “whatever” fee to get the rest of the information. He’s certainly not giving it away! I’ll likewise agree that it’s definitely a lot more race than street oriented, in that it starts at 10.5:1 compression and the information at hand only shows a .75 increase in LSA for each point gained in compression. I’m going to guess that in reversing the formula for decrease in compression wouldn’t work out nearly as well for a lower compression engine such as a smogger eighteen or 360. I do know of some 318 and 360 stump puller fast rate grinds set on a 108 LSA that work very well for towing and hauling applications, even though those applications call for an LSA in the 106 to 107 range by the rule. A 108 is probably about as narrow of an LSA as I would want to go in that type of application. If any testing has been done in that area, I’ve not came across it. But I’ll admit I’ve not really looked too hard either. I try to target at least 9:1 compression or better, which amounts to only reducing LSA by “about” 1. I imagine that the curve for lower compression would have to be less linear than .75 degrees for each point just for the sake of drivability. I do know that a 9:1 360 in a heavy application with a 110 LSA has much less off idle torque and less usable power than it does with the same cam specs set on a 108 or narrower LSA.

 

[273]

Correlation is not the same as causation.

I think DV 128 formula has more to do with what Mean416 says here, it's probably correlation, most times a dyno shows in general, engines were talking about tighter lsa gains in the rpms were talking about.
But I also agree with Newbomb Turk you could do a lot worse than use the 128 to get into the ballpark.
But that only gives lsa, valve lift is pretty easy to figure out, which leaves mainly overlap & duration to figure out so for most like the OP it don't really overly help them. According to DV next you pick overlap and that gives you your duration, other than saying what tow/street/streetstrip/race etc.. General overlaps are. But doesn't give a particular method for getting overlap for eg.. a 6500 rpm 2.02 360 or a 5500 rpm 1.88 318.

The only way I know to figure that out his way is pick what off the shelf I'd go with find it's overlap and figure it into his 128 system.

 

[Hysteric]

Yeah, I kinda figured this thread would be fairly polarizing once bringing up the 128 rule.

His formula suits his design philosophy. Here's an engine Mike Jones built for himself, look at the duration, split and LSA its a HR from memory.

There are very few pump gas 355" SBC engines that will out-pull my boat engine
It's 10:1 with ported 492 heads, Performer RPM, and Holley 600.

RPM---TQ--BHP
3200--436--266
3400--443--287
3600--445--305
3800--444--321
4000--443--337
4200--440--352
4400--440--368
4600--441--386
4800--441--403
5000--432--411
5200--422--418
5400--412--423
5600--400--426

The cam is 216/220, on a 112 LSA, and 108 ICL

Some generalizations from Mike:

If you took an engine, with a head/manifold that's all done at 6,000rpm, and you are going to look at the power from 3,000-6,000, you could use different durations to get the results you want.

If you want the results to show that the tighter the LSA, the higher the low-end power, and the lower the top end power, you go with the proper cam duration for 6,000rpm.

If you want the tighter LSA to make more power everywhere, you take out compression, and add a bunch of duration.

If you want the wider LSA to make more power everywhere, you add compression, and take out a bunch of duration.

 

[rumblefish360]

I believe wider LSA belongs more on a street car for better idle quality, or a light car, or a car that is going to use a power adder.
narrower LSA cam

Street car for manners. Yes! Oh yes.
Super charging, etc… yes.

I don't think LSA comes down to some formula "discovered" by Vizard. Vizard has become a snake oil salesman, tarnishing his legacy with crap like the "128" formula.

Correlation is not the same as causation.

Vizards 128 formula takes into account basically one thing, average torque production on a dyno. That’s what I don’t like about it. Unfortunately in the real world we have so many other variables to take into consideration (fuel mileage, idle quality, off idle drivability, vacuum for power brakes, just to name a few) that must also be considered.

Mean 416,
Where is your dyno testing [ or anyone else's ] that disproves the 128 rule????????????

The thing I think everyone misses or forgets is the formula is designed around a Chevy 350 engine. I don’t think he is a snake oil salesman since he is t selling anything, just his books. You would do the same and anyone that says they would t push there own books is just a dead *** lier saying so just to get a rise out of someone.

After all…. Only a fool throws money away.

Here’s a question…

Does the formula change for the CID
Does the ………………………. For the make of the engine?
What about valve angle?

It seems most times I read this topic, this is ignored and not spoken about. If the formula works for a SBC, what about a SBC with altered valve angles? How about a SB MoPar? Or a W9?

Not only are the valve angles a changer, *I Think*, what about intake runner length? If the runner is longer, would you need to tighten up the LSA?


Just food for thought…..


IMO, if Dans future cars comes with a 318, I don’t think anyone would know the difference with a 112 vs a 110 or a 110 vs a 108 LSA. Honestly, for what Dan wants and is doing, an off the shelf cam on a 110 in a 318 would be just fine.

If he wants an “Idle” sound at idle or a smooth idle, he will let us know. At a 110, it’ll sound like a typical muscle car hot rod most build.

 

[Garrett Ellison]

Exactly right! DV says the 128 formula is the same for all inline valve engines whether they be small ford, Mopar, Chevy, FE Ford, BB Mopar, etc. His tests with “semi hemi” engines of the BBC or Cleveland/385 Ford variety dictates the same formula with “134” instead of 128. So a true Hemi would probably have an even larger number as a staring point. One other thing this formula doesn’t cover is fuels other than gasoline. Mike Jones (Cam King) covers some of the cam requirements of methanol and it’s a worthwhile read for those who intend to race with alcohols.

 

[rumblefish360]

Good reply. You’re on top of it. My point exactly.

But is there a change form going from an LA head to a W9 with its superior head flow and altered valve angles? Or does it really matter? Since everyone likes splitting hairs on this (& other subjects) let’s split hairs here!

IMO, in a daily driver like Dan wants and many other applications, it’s just not worth it. Racing for the money? Let the dyno testing begin!

 

[Newbomb Turk]

Good reply. You’re on top of it. My point exactly.

But is there a change form going from an LA head to a W9 with its superior head flow and altered valve angles? Or does it really matter? Since everyone likes splitting hairs on this (& other subjects) let’s split hairs here!

IMO, in a daily driver like Dan wants and many other applications, it’s just not worth it. Racing for the money? Let the dyno testing begin!

It doesn’t really matter.especially with in-line wedge heads. They are already under valved and they can use all the overlap you can give them until you run into other issues.


Even a Pro Stock engine wants more overlap, but getting there costs more power than the overlap makes.