As my new 383 nears completion I've come to the part where I need to select a cam for it. I started playing around with Engine Analyzer Pro and Drag Racing Analyzer... these programs seem quite accurate as I've put several proven combos in them and they've all come within a tenth or two of reality. Anyway, here is my motor: 385 with 11:1 compression, Canfield 195 heads (2.055/1.60 valves, as cast), professional products intake (vic jr copy), 750cfm mechanical Speed Demon, 1.75" long tubes, MSD ignition. Car is 3300lbs, 27x11.5 slicks, 3.92 gear, TH350 with 9.5" converter that stalled approx 3500RPM behind my old 400HP motor. The car is 80% drag race 20% street so streetability is not really a concern for me but I would like to run on 93 octane pump gas. It also has a nitrous kit that'll be used but I'm aiming for fastest N/A times possible.

Now, leaving all else the same, I started punching in various cams (all solid FT) that looked appealing to me and came up with some interesting results:

Crane Powermax (244/252, .518/.536, 112LSA):
Peak Tq: 455 @ 4750RPM (avg = 423)
Peak HP: 477 @ 6250RPM (avg = 406)
ET: 11.21 @ 120mph

Crane SNP (244/252, .518/.536, 106LSA):
Peak Tq: 451 @ 3500RPM (avg = 414)
Peak HP: 464 @ 6000RPM (avg = 396)
ET: 11.33 @ 118mph

Lunati 08101 (248/259, .528/.534, 106LSA)
Peak Tq: 452 @ 3500RPM (avg = 414)
Peak HP: 464 @ 6250RPM (avg = 397)
ET: 11.33 @ 118mph

Comp XS290 (252/260, .540/.558, 110LSA)
Peak Tq: 470 @ 4250RPM (avg = 422)
Peak HP: 461 @ 5750RPM (avg = 400)
ET: 11.26 @ 118mph

Comp 294S (248/248, .525/.525, 110LSA)
Peak Tq: 466 @ 4250RPM (avg = 413)
Peak HP: 453 @ 5750RPM (avg = 391)
ET: 11.33 @ 117mph

Does this seem real-world? Take the Crane Powermax vs Saturday Night Special. Both cams have the same duration and lift but one is 112LSA while the other is on 106LSA. Shouldn't, in theory, the 106LSA cam ET quicker? It just seems weird to me that the most street friendly looking cam would be the best choice. Would you trust these comparisons or recommend something else?

Look, even good old D2k is good for I figure w/i +/- 5 percent so go!!

And I also figure that it is NOT the numbers, but rather the trends between engine combinations that are more important b/c it is just a SIM, program after all!!

pdq67

PS., and that's why I picked the old CC 282S solid cam for my grunt "tow-truck" 496 motor.....................

The 106 Crane and the 112 Crane are the exact same profiles---Your program is wrong, the 106 will be much faster at the track. I would also expect more than 8 BHP difference between the CC XS290 and the CC 294S.
What do you use for input in your program, .020" or .050"? I might have some numbers for you to look at......

UDHarold

this is your chance, broke. You can get what's essentially a custom design cam on a quality core ground on the best machines. PM to Harold soonest.

The 106 Crane and the 112 Crane are the exact same profiles---Your program is wrong, the 106 will be much faster at the track. I would also expect more than 8 BHP difference between the CC XS290 and the CC 294S.
What do you use for input in your program, .020" or .050"? I might have some numbers for you to look at......

UDHarold

I'm using .050. Here is the input screen displaying the info for both cams. Does something seem off here? I also figured the 106LSA should overpower the 112LSA but not sure why this program disagrees?

http://beater.org/enginean1.jpg

http://beater.org/enginean2.jpg

Broke,

Computer programs work generally(LOL!!) the way the programmer wrote it. I cannot explain why it does not agree with the real world, but in SBCs 106 is fast at the strip, 112 is more for street driving, which is how Crane sells it.
Here are some popular cams that I make for SBCs. You will need one on a small base circle if your rods have not been cut for stroker engines.
272/278@.020, 243/249@.050, 155/161@.200, .523"/.545" Gross valve lift, .016"/.016" valve lash, 108 LSA.
At .020, IVO 30 BTDC IVC 62 ABDC EVO 66 BBDC EVC 32 ATDC
At .050, IVO 17 BTDC IVC 46 ABDC EVO 56 BBDC EVC 13 ATDC

278/284@.020, 249/255@.050, 161/167@.200, .545"/.550" Gross valve lift,
.016"/.016" valve lash, 106 LSA.
At .020, IVO 35 BTDC IVC 63 ABDC EVO 70 BBDC EVC 34 ATDC
At ,050, IVO 20 BTDC IVC 49 ABDC EVO 57 BBDC EVC 18 ATDC

The Crane Saturday Night Special is 280/288 at .020. Compare it to my 272/278, which is bigger above .200. My 272 lobe makes the engine think it is a 268 when the intake valve opens, but a 276 when it closes, plus it is 3* bigger at .200. The rest are all similar, and trick the engine into thinking it is a small cam on the opening, for less reversion and a higher port velocity, and then turn out to be a big cam at .200 and above, with more time to fill the cylinder with that high velocity port flow.
This has worked for 27 years.
Let us know what your engine dyno program says, at both .020 and .050.

UDHarold

The man has spoken again!

Harold,

Somebody needs to put all you posts together so we all can easily go back through them!!

pdq67

Broke,

Computer programs work generally(LOL!!) the way the programmer wrote it. I cannot explain why it does not agree with the real world, but in SBCs 106 is fast at the strip, 112 is more for street driving, which is how Crane sells it.
Here are some popular cams that I make for SBCs. You will need one on a small base circle if your rods have not been cut for stroker engines.
272/278@.020, 243/249@.050, 155/161@.200, .523"/.545" Gross valve lift, .016"/.016" valve lash, 108 LSA.
At .020, IVO 30 BTDC IVC 62 ABDC EVO 66 BBDC EVC 32 ATDC
At .050, IVO 17 BTDC IVC 46 ABDC EVO 56 BBDC EVC 13 ATDC

278/284@.020, 249/255@.050, 161/167@.200, .545"/.550" Gross valve lift,
.016"/.016" valve lash, 106 LSA.
At .020, IVO 35 BTDC IVC 63 ABDC EVO 70 BBDC EVC 34 ATDC
At ,050, IVO 20 BTDC IVC 49 ABDC EVO 57 BBDC EVC 18 ATDC

The Crane Saturday Night Special is 280/288 at .020. Compare it to my 272/278, which is bigger above .200. My 272 lobe makes the engine think it is a 268 when the intake valve opens, but a 276 when it closes, plus it is 3* bigger at .200. The rest are all similar, and trick the engine into thinking it is a small cam on the opening, for less reversion and a higher port velocity, and then turn out to be a big cam at .200 and above, with more time to fill the cylinder with that high velocity port flow.
This has worked for 27 years.
Let us know what your engine dyno program says, at both .020 and .050.

UDHarold

I ran both of those through it. Do these numbers look ballpark to you? I also took a screen shot of all the data it calculates about the camshaft, does something look wrong with them? I noticed a few of the numbers it calculated based off the .050 events I entered are slightly off, possibly just rounding things off?

Peak Tq: 451 @ 3500RPM (avg = 417)
Peak HP: 466 @ 6250RPM (avg = 398)
ET: 11.29 @ 119.10mph

Peak Tq: 446 @ 3500RPM (avg = 417)
Peak HP: 476 @ 6250RPM (avg = 401)
ET: 11.27 @ 119.62mph

http://beater.org/camdat1.jpg

http://beater.org/camdat2.jpg

I'm certainly not trusting this program to select the right cam for me - It's just I see a lot of folks on here using these simulated dynos to aid in their builds so I figured I'd see what it says. As soon as I saw it favoring the 112LSA cam over the 106LSA I thought something was off - and if its off about that, what else might be off? I also noticed that the popular Desktop Dyno software also favors the 112 over the 106. Maybe it's some sort of conspiracy.

the 106 will make more peak HP and Tq, but it will be over a much narrower RPM band than the 112. If you've given the program the weight of the Chevelle (heavy) it may be calculating that you'll go faster with a broad power band. It might be right too. You still can't race dynos or dyno simulation programs.

Your best bet: listen carefully to Harold.

Broke,

Your analysis using my profiles give a clue to how the program works.
The timing numbers I provided are straight from my computer printout.
Your program divides the .050 duration by 2, as if my profiles are symmetrical, then calculates LSA and ICL/ECL from those numbers.
My profiles are always unsymmetrical, and the amount at .020 and .050 are different.
The numbers I provided for the 249/255 are accurate, the cam is on a 106 LSA, not a 107, ICL is 104, not 104.5, ECL is 110, not 109.5.
Where the duration numbers 304/311 came from, I haven't a clue. This cam is 293/299 at .01066667", the top of the designed ramp, where the .016" valve lash comes from. Deflection in the valve train after lash is taken up adds a few thousands to that.
I use .020" as a reference point for the same reasons we all use .050"---It gives us a common point to talk about.
The valve opening points and closing points are extremely important, more so than the opening/closing points at .050". Without going into why--I've done it here on Team Chevelle many times--but I rate the intake opening and the exhaust opening of equal value, and the most important. The intake closing point to me is a distant 3rd---Other cam companies disagree--and the exhaust closing point the least important.
If you want to talk to me, my number is 662-301-1245, mostg of the time during the day. If I don't answer, I had to go into town.

UDHarold

Harold is it possible to get those ground onto a P55 core?


My future combo in the works.. what do you guys think?

355 SBC
10.5 compression
Brodix IK 200
Team G 7530
850 Mighty Demon
1 3/4 headers with dual 3 inch exhaust.

278/284@.020, 249/255@.050, 161/167@.200, .545"/.550" Gross valve lift,
.016"/.016" valve lash, 106 LSA.
At .020, IVO 35 BTDC IVC 63 ABDC EVO 70 BBDC EVC 34 ATDC
At ,050, IVO 20 BTDC IVC 49 ABDC EVO 57 BBDC EVC 18 ATDC

full size Camaro..say 3800 lbs.
4500 stall converter, TH-350 trans
4.56 rear axle
28 inch MT Drag radials
Cal-Tracs

Hoping it might be possible to break into 11's in the 1/4 mile with sea level DA.

Harold, we are not worthy.....

analyzed the guys programming, cool.

Ditto Tom!!

pdq67

Tom, PDQ67,

Please don't my head swell any larger, hats are getting hard to find.
This is all just part of the job, and I love doing it.

Pastry Chef,

I have Crane SBC and BBC cast iron cores in stock. I can get P55s, but Engine Power won't sell to me direct yet, so I have to get them from Comp cams' stock, with a premium surcharge. This surcharge would be passed on to you.
I have had no reliability problems with the Crane core. You will need to use outer springs only and some Rotella, or its equivalent, during break-in.

UDHarold

Very good Harold,

Thanks for the info, I'll likely give you a jingle in 2 or 3 months time to get a cam made.

it's fun having you stop by Harold.

I've learned a lot, and wasn't exactly ignorant to start with.