Currently laid off because of the GM strike and its a rainy day here in Michigan today, so i'm getting some reading in. David Vizard has some interesting writings no one seems to follow. Picking lobe sep is just one. He does explain correct compression as being a good thing to have to enhance air flow and states the higher you go with compression the wider the lob sep needs to be and my pipemax 4.5 suggests the same for my combo as 113-114 being whats needed with 262/270@50 duration. This lob sep is something I never see in N/A engines, power adder engines usually. Can anyone add anything to this mind set? I have always had the mind set 108/110 was what you used in an N/A engine.

First, I responded to your PM already.

Second... unless you're going to run about 15:1 CR and spin it 8000 RPM, no way in He11 I can see you needing a cam w/ that wide of an LSA N/A (unless it also recommends reducing the duration quite a bit, which wouldn't make sense to me, either).

DV has written a lot of stuff, and I own a lot of his books. However, some of his approaches, such as how he determines cam LSA based upon overlap, etc., seem tailored to fit all his SBC testing, despite his claims that they're universally applicable (for the most part).

I agree. His stuff seems way out there in my world. His lobe sep graph that figures lobe sep based on bore and valve size shows 100* lobe sep. for my combo. Never heard or seen anyone doing this. And now His lobe sep based on compression ratio goes totally out of the park the other way. Not looking to change cams right away, but I have been looking at the Ultradyne SLT cam grinds. They look to have a fairy quick ramp. Can these be run on the street without issue? Looking for a grind for 12.5:1 511 with 5000+stall and at 3380# race weight. The current ultradyne I'm looking at is very similar to what Dwayne spec'd and i'm using. the ultradyne has faster ramps and on a 108LDA vs my 110.

You can computer model and theorize all that cam stuff endlessly.

In the end, there’s only one way to know if it’s what your motor of combo wants....... and that’s to test it.

If the computer says it’s better, but your car is slower.........which are you going to believe?

Faster ramps will require higher spring loads(to achieve equal rpm), which will reduce the reliability/longevity of the components used....... no way around it.

The cam you have tries to balance that somewhat.

Would a more aggressive cam make more power? Probably.

The question becomes, how much more power does it make........and can I live with the ramifications of the more aggressive cam with the way the car is being used?

114lsa?
That doesn’t turn out very well in most cases with a build like yours.

Years ago i ran a 107 LSA comp cam Dwayne specced on a 416 motor that was just under 12 to 1
Scott Brown knew my motor specs well and suggested i try a 112 cam he designed
Car went 10.38 with the 107 cam, best ever with the 112 was 10.55
The 112 killed the 60 foot. Acted like novacaine when the car launched.
My take was more vert and compression it might have liked the 112 more.
Real good heads and lots of compression imo are necessities for an NA street/ strip motor to make that swap worthwhile at the track, maybe huge cubic inches might help a good bit top. Probably would

I'm the freakin' poster child for that... I don't even bother w/ the software stuff anymore. Empirical data all day long, please.

I agree, In the end its just entertainment for sure. 114 would not be a good direction after what I saw in a scott brown cam with 112lda in my 408. That thing was a pooch off the line and scott aways stood by that 112lda, said it might be soft off the line, but quicker thru the traps overall. I never seen it. Went to a 108lda and a 5200 8" from a 3500 10" and car went from mid 11's to high 10's.

I too have read a lot of DV stuff, most of it is spot on. One time I freshened an engine for a guy and all the exhaust valves were really pitted, I just thought it was cheap valves. It had a 108 camshaft installed at 102, on the dyno exhaust temps were very high, I took that to be the issue with the exhaust valve problem, got a new cam same lift and duration at 110 installed at 108 and the engine made 65 HP more and the exhaust temps came down to a normal range. Sometimes as mentioned an engine just needs what it wants, a lot of variables that maybe don't get inputed into a computer program the right way, who knows. I picked the replacement cam using performance trends soft ware, and pipemax software.

I had a similar experience. Scott Brown spec'd a cam for a 10.8:1 compression Edelbrock headed 440 combo I had w/ a 112 LSA (254/266 at fifty). I wasn't happy w/ it at all. Switched to an Ultradyne on a 108 (259 at fifty straight pattern) and the car went quicker and faster.

A lot of factors to consider when the LSA is being chosen for a particular cam. As for not seeing that kind of LSA on an NA engine depends on the NA engine. My junk is 117 NA, our dragster runs a 114 and the heads up car, which is also NA is even wider....Just depend on the application

No kidding Al? 117 lda or even 114 on an N/A deal? What in the combo requires being that far outside the norm N/A engine? Just trying to learn something here. Thanks, that's interesting.

I was told years ago(40+) by several people who worked for three different camshaft makers in SO CA that the LSA would help determine where the motor would make the most power, closer LSA would loose some power in the upper RPM limits(above 4000 RPM back then) and wider would loose power down low, below 4000 RPM.
I have used several different grinds in BB Mopars with 104 and one 101 LSA solid lifter cams
The one motor with the 101 LSA was a pump gas street stock stroke iron headed 440 that was installed at 99 on the ILC, the owner said that motor pulled real hard up to and over 7500 RPM
The 104 Isky grinds where used in several different higher (above 11.5 to 1)compression M.W. bracket motors, I would shift those motors them between 6400 and 7200 RPM

Winner, winner, chicken dinner!

Yeah Pro Stock stuff has been in the 120 range and some Super Stock stuff I've seen down in the high 90's. So LSA and LCA are just what it takes to get the job done. How you figure out what it takes to do the job is the tricky part.

Yep. Like i said above a bigger motor with good heads and lots of compression is going to shine with a wider LSA camshaft.
Hemi super stock because of rules is a much more limited motor and a more rpm band sensitive narrow LSA cam will shine.
For the typical bracket 10 and 11 second car that isn't light like a pro stock or heads up car, a narrower cam is typically gonna make the car ET better
Not gonna find to many 15 to 1 440’s or 416’s with eddie heads bracket racing because among other reasons fuel is expensive. Most “ class “ cars run narrower stuff. Talking stock and superstock

Chip, yea, Scott Brown was all about wider cams, no matter the situation. I was stupid letting him talk me into trying his cam. It didnt make any sense, and the results ended up predictable

I used to chase this stuff around but these days I use 112 in all of my street stuff with 4 degrees of advance. I don't even think about it anymore. Maybe I'm leaving peak power on the table but I don't care. 112 in at 108 works great on pump gas street engines, especially with EFI.

112 lsa is 112 lsa , no matter how much you advance the cam

On the street where the big inch big blocks you primarily fool with will blow the tires off at the hit, you likely wouldnt notice any difference. You are not wringing cars out at the track, are you?
Its not like the difference is huge in most cases anyhow. I learned over the years( at least to me) it takes 3 tenths or so to notice in the seat of the pants driving around after changes on the street and then going to the track.

Car runs 10.20 on the track and you drive it on the street. Make changes and drive it on the street and it feels the same. Take it to the track and the changes result in it going 10 flat. You think wow......wouldn't have guessed that pulling up to the ET shack

That’s true....... but it’s installed at some ICL.

True,