Good Cam Choice?

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Newbomb Turk said:
That’s what I used to think but Godbold says in his book that they use the wide LSA for piston top geometry. He says even a Pro Stocker (pre EFI and rev limit) can use a tighter LSA but the valve pockets get too deep and the BSFC goes up. So they widen the LSA to get the valve notches less deep
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Billy’s a smart, smart dude with undoubtedly way more knowledge/experience than most so I wouldn’t dare question him. I have personally watched a dyno test where a 121 lsa carried 8 or so more above peak (over something like a 108 lsa) and extended the curve out another 200 or so rpm on a 478cu in, 8000+ rpm big block so that’s where my knowledge comes from. There are so many damn factors to consider as to why things happen or are happening, and I certainly get that.
 
Newbomb Turk said:
That’s what I used to think but Godbold says in his book that they use the wide LSA for piston top geometry. He says even a Pro Stocker (pre EFI and rev limit) can use a tighter LSA but the valve pockets get too deep and the BSFC goes up. So they widen the LSA to get the valve notches less deep
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I also seen somewhere they said the widen the lsa to kills some torque to help traction during launch.
 
42C36EFA-509B-422F-AA02-6B4D280AA396.png


Another graph from the engine masters show. This one on a 440 mopar with 118, 112, and 106 LSA cams
 
273 said:
The tighter lsa made a bigger difference on this one. Seems from the two examples under 6500 rpm you probably want a tighter lsa.
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If average torque production is what you’re after then yes. But tuning an efi setup or driving a stick car can be difficult with the tight lsa cam. Hence the entire discussion.
 
TT5.9mag said:
If average torque production is what you’re after then yes. But tuning an efi setup or driving a stick car can be difficult with the tight lsa cam. Hence the entire discussion.
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Too bad there wasn't driveability shootouts.

I wonder if given up duration to keep a tighter lsa for similar overlap or giving up lsa for duration is the better way or a mix of the two, Or does it all basically work out in the wash?
 
273 said:
I wonder if given up duration to keep a tighter lsa for similar overlap or giving up lsa for duration is the better way or a mix of the two, Or does it all basically work out in the wash?
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I dont think anything is a wash, I think there are positives and negatives to going both ways. It’s all really combo dependent. Like @Newbomb Turk said about pro stock giving up lsa to keep the duration and get more room on the P to V and keeping a piston design that works better. In their situation the duration is more important.
 
I would take the extra 30-40 ft/lbs@ 3500 rpm in post #43......any day of the week.
 
After D. Vizard tested the 19000+ cam combinations for Crane Cams, there many more cams in the catalogue with tighter LSAs...than there was before the testing was done.

Isky cams has most street cams on 108LSA.

Crower had a performance shelf grind for a 440, HFT, #206-HDP...that was 105 LSA.
 
I have a Hughes cam custom grind to 112 LSA instead of 108. Has really good Street manners with a manual trans, but also hooks good and strong on the strip.
My goal was to have more vacuum for a Brake booster, but its a different car in the meantime that has no brake booster. Anyway, i like the 112.
And no, i have no EFI, just want to share my expirience
 
DieWilde13 said:
I have a Hughes cam custom grind to 112 LSA instead of 108. Has really good Street manners with a manual trans, but also hooks good and strong on the strip.
My goal was to have more vacuum for a Brake booster, but its a different car in the meantime that has no brake booster. Anyway, i like the 112.
And no, i have no EFI, just want to share my expirience
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Now here come the "experts" to tell you how much "more" power you'd had going with a 108 or less. Screw um. lol
 
Not only did the 108 cam in the Holdener test make 30-40 ft/lbs more at 3500 rpm.....it also made more peak hp than the other two. Hmm....
 
US car companies seem to have this pre-occupation with wide LSA cams in production engines.
The factory cams in the British Leyland engines had 107.5 LSA. The factory performance cams had 102.5 LSA.
A 998 cc Mini engine made 94 hp with one of these cams. That would be 490 hp in a 318 ci engine.
 
Even the slant 6 cams are ground on cores from 106-109 LSA for whatever that's worth. My thinking on it is, the factories wanted a good vacuum signal for vacuum accessories and good street manners.
 
All I know is the cam in my 410 with 5 speed manual idles @ 850 rpm with 14 inches of vacuum, will pull down to 1000rpm in fifth gear and pull away like a train and does not jump and buck slowing down in gear and is good on fuel for a 410 (21mpg) on a run with 3.91 diff ratio. My cam is a 242 @ 50 thou with 610 lift on a 112 lobe sep. It makes 430 rear wheel hp, approx 540 or 550 flywheel hp. It has trick flow heads and about 11/1 compression and will easily rev to 6500. I wouldn't trade the 112 sep for anything!
 
RustyRatRod said:
Even the slant 6 cams are ground on cores from 106-109 LSA for whatever that's worth. My thinking on it is, the factories wanted a good vacuum signal for vacuum accessories and good street manners.
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That’s a big part of it. Also, you can add to that the added complexity of getting a carb to work with tighter LSA’s. The factory doesn’t care about power at WOT. And that’s what the dyno is measuring. WOT. Not at part throttle, low load.
 
Bewy said:
I would take the extra 30-40 ft/lbs@ 3500 rpm in post #43......any day of the week.
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Come on you’re smarter than that. The difference between the 112 and the 108 was not 30-40lb/ft. The 120 was an outlier and almost no one installs an aftermarket cam with the lsa up there. The point was the 110 that the OP has isn’t giving up hardly anything because of the LSA.
 
All I'm going to say is that I'm going to read this post carefully as I think that I will learn more about cams. Thanks to the OP.
 
TT5,

You are right. The 30-40 ft/lb difference was between the 108 & 120 LSA cams.
What is indisputable is the fact that the 108 cam made more tq & hp than the other two cams in the rpm range tested, except at one spot it equalled the other two.

Similar trend in the test you posted in post #53, except the 106 cam lost a few hp right at the top end.
As D. Vizard says, the right cam costs the same as the wrong cam....
 
Bewy said:
TT5,

You are right. The 30-40 ft/lb difference was between the 108 & 120 LSA cams.
What is indisputable is the fact that the 108 cam made more tq & hp than the other two cams in the rpm range tested, except at one spot it equalled the other two.

Similar trend in the test you posted in post #53, except the 106 cam lost a few hp right at the top end.
As D. Vizard says, the right cam costs the same as the wrong cam....
Click to expand...

I just don’t like saying “right” cam or “wrong” cam. They’re just cams that do different things. There is no one cam for any engine combination that does everything perfectly.
 
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I agree that cams are 'different'. But I believe if one does careful research, one can choose a cam that is optimised for the intended use.
By research I mean:
- decide on what you will accept for idle quality & rpm
- decide on max usable rpm
- make sure the induction & exh system supports the intended rpm range
 
TT5.9mag said:
I just don’t like saying “right” cam or wrong “cam”. They’re just cams that do different things. There is no one cam for any engine combination that does everything perfectly.
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Agree take a 5.9l magnum long block can run a stock cam to the 380 hp create cam and beyond.
Which is right? Out of the probably dozens choices. Depends what you want, that's why I generally see as a personal choice based on your level of compromises, why it's hard for others to pick for you.
 
As hard as it is for some to believe, maximum power isn't everyone's top priority when choosing a camshaft.
 
RustyRatRod said:
As hard as it is for some to believe, maximum power isn't everyone's top priority when choosing a camshaft.
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Yeah, that one always baffles me. If someone doesn’t want max power just open a catalog, pick a cam two sizes smaller than what you think you should have and run it.


Yet no one does it and in every one of these threads the guy always wants more power, but they usually don’t want to do the work to get drivability in shape.
 
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