cam question

yellow rose said
Also, it doesn't take a very long search to learn that a "wide" LSA does NOT make more bottom and mid range power and torque over a "narrow" LSA. In fact, it is quite the opposite.

I like this statement.

For the rest of us,lol
A wide LSA has a tendency to push the ICA later and later, which steals compression degrees. which reduces trapping, and with NO OTHER CHANGES, softens the bottom end, and leads to higher stall TCs and such. This is terrible for a heavier street-machine with a small engine. Something like a Barracuda 318 at 3600# car and driver. I have always been confused with the why of Mopar's decision to run the 114LSA 340 cams, and why they stuck with them in the 73 up low-comp engines..
On the street with street gears, and a 4-speed; I have never been able to reconcile Wide LSAs because at best, the run to 65mph is ~1.5 gears. So I'd rather have the down-low torque, of a narrow LSA, coupled with a few more ponies at the top, than the alternative with a "wide" LSA.
OK I get that the auto guys can get away with it, by running a hi-stall, but that does nothing for the lost power spike. Plus the Wide LSAs kill the overlap cycle, that headers can really exploit.
And IMO, hydros are about the worst choice for a NA streeter. Yeah they're quiet, and they're maintenance free; but they cost you in every other way.
So a wide-LSA hydro cam, of all flat-tappet cams, for a NA street-performance is, IMO, the least performance oriented, and especially so when installed in a lo-compression street engine; so my question is why in blazes did Mopar stick them into the Low-c 340s?
Oh I know............... the light just went on. Firstly is the 340-specific idle-sound,and then; what year did Mopars go to EGR valves and/or airpumps? Another strike against wide LSA cams.
Like YR said, 110s are mid-pack.
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And IMO, the widest I would ever run. My next cam will be a "narrow" LSA solid flatie, with "lots" of overlap,lol.

Here's some food for thought; For my next cam, I'm liking a solid at;
284/288/on 106. This by the math generates 74* overlap, and this cam may have .050 numbers of 246/250
But the spec is say at .006 , and the actual seat-closed to seat-closed might be
296/300 but after lashing might be
266/270 with an Ica of 58*.

Lets compare that to the same 284/288 but on a 114, and now a hydro;
seat closed to seat-closed might be 310/316, and the overlap maths to 58*. The ramps are typically 44* so at .050 it looks like
244/248/114, but the actual closed intake might not be until 81degrees!
Notice the .050s are very very similar
Now lets install these in an 8/1 360.
First the solid;
Static compression ratio of 8:1.
Ica of 58*, elevation 500ft
Effective stroke is 2.93 inches.
Your dynamic compression ratio is 6.73:1 .
Your dynamic cranking pressure is 127.58 PSI..............................127.6
V/P (Volume to Pressure Index) is 113 ......................................... 113
then the hydro;
Static compression ratio of 8:1.
Ica of 81*,@500ft
Effective stroke is 2.33 inches.
Your dynamic compression ratio is 5.56:1 .
Your dynamic cranking pressure is 98.01 PSI................................. 98
V/P (Volume to Pressure Index) is 69 ........................................... 69

to get the pressure back up to match the solid, I get
Static compression ratio of 9.8:1.
Ica still 81*@500ft
Effective stroke is 2.33 inches.
Your dynamic compression ratio is 6.73:1 .
Your dynamic cranking pressure is 127.58 PSI.............................. 127.6
V/P (Volume to Pressure Index) is 90 .......................................... 90
But check out the VP is still in the basement at 90

To max out the pressure at say 165psi
Static compression ratio of 11:1.
Still 81*/500ft
Effective stroke is 2.33 inches.
Your dynamic compression ratio is 8.16:1 .
Your dynamic cranking pressure is 165.15 PSI.................................. 165.2
V/P (Volume to Pressure Index) is 116 ............................................ 116
notice the still weak 116vp

So what about the solid? Glad you asked
Static compression ratio of 9.8:1.
Ica now 58*, still 500ft
Effective stroke is 2.93 inches.
Your dynamic compression ratio is 8.20:1 .
Your dynamic cranking pressure is 166.23 PSI. ................................ 166.2
V/P (Volume to Pressure Index) is 147............................................. 147
Notice the killer 147VP

What do the numbers mean?
Well firstly the .050 numbers come out near identical, so the absolute power numbers will be very similar........ if they also had same overlap.And they do compare well with the 56* of the solid to 58* of the hydro. So far so good.
But check out the VPs; of 113solid to 69hydro, both at 8/1 Scr..... Or of 147solid/90 both at 9.8 Scr .. So what's that mean?
Well VP is a measuring stick we use for the bottom half of the rpm range, and these numbers clearly show that the solid to be 63% stronger in that window.
Now tell me, How much time does your streeter spend in that zone?
Well with an automatic, you can run a 3500TC and the only time your engine will be there, it is also not gonna be at WOT, so nobody cares.
But if you have a manual trans, you are gonna be in that zone like 95% of the time.
Next is the difference in LSAs. The narrow on will make a lil more power at the peak, and a lil less at the bottom, so the curve gets tilted in favor of the manual trans 4-speed which has a narrower powerband requirement... and the bottom end loss is eclipsed by the very strong VP... so winner to the 4-speed. For the automatic, the lower end id erased by the 3500TC, so no big deal there, either way. But, the trans has a 1-2 powerband requirement of 59%.. That is to say if you rev your auto to 5800, then on the 1-2 shift, the Rs will fall to 59% of that or to 3420, or in this case to 3500 plus, which is a powerband requirement of ~2400rpm. In other words your engine better be making some torque down there. Whereas the 4-speed will drop to 72% or from 5800 to 4200 which is 1600rpm so it doesn't need a wide powerband.
And now the hammer;
With the solid, the power extraction will be about 118*, compared to the hydro at 101* .. Guess which one is gonna suck gas big time! Hyup the hydro.
So with the hydro, and an automatic with a 3500 TC, and say 3.55s, the engine will be at ~2870@65mph, and sucking gas to beat all. Whereas, the solid with a manual trans has such a preponderance of low-rpm power that if He wanted to, he could run 2.76s But you know, I like to be fair, so with 3.55s, it too will be running 2870. The difference is that the solid will have the carb nearly closed and is running barely off the idleports.... whereas the hydro/auto will be running quite a bit further up the transfers.
So that's a double whammy to the hydro; first is low VP, and second is the wide throttle-opening.
With all that VP. the solid/manual trans could easily run an overdrive, whereas for the hydrp/auto, an overdrive would just make things worse; .69 x 2870=1980, and I doubt with a VP of 69 she could pull that, I mean even a slanty has better VP than 69 (87 IIRC) and it has a hard time to cruise 65 at under 2000.

So the point is this; there is absolutely no downside, performance wise, to running a big solid-lifter cam on the street, and you don't need the big compression numbers...... so what you didn't spend on new hi-comp pistons, you can now spend on the valve gear.

That's my story and I'm sticking to it,lol.