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Discussion Starter · #1 · (Edited)
I'm having some trouble making my choice of cams. I'd appreciate some input on what everyone thinks would work the best.

The hypothetical setup would be: Explorer PI motor, Electric water pump, 3800 stall, J-mod, 4.10s.

My goal would be to find whichever cam allows the most area under the horsepower curve between around 4000rpms and 6000rpms.

My choices soo far are:

Crower Stage 2, low lift N/A:
ADV Duration: 266 / 270
.050 Duration: 220 / 224
Advertised lift: .532 / .532
LSA: 114 I think?
Note: I'm not sure this cam will make the powerband thick enough, but its #1 on my list soo far.

Crower stage 2, high lift N/A:
ADV Duration: 268 / 272
.050 Duration: 224 / 228
Advertised lift: 559 / .570
LSA: No Idea
Note: I don't think I'l lbenefit much from the extra lift.

VT Stage 2 N/A
ADV Duration: No idea
.050 Duration: 225 /235
Advertised lift: .560 .575
LSA: 108
Note: I think the LSA is too low.

I'd appreciate if you would give reasons why or why not to use certian cams.

Thanks,
-Ryan
 

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i see you're going for very good 1/4mile times :)

well the super tight LSA of the VTs makes for a very peaky curve for the sake of putting out a high peak #....it think this would be more geard for close-ratio manual trans cars that can keep it circling the peak HP RPM very closely

i dont know if you ever saw this, but my cams, which were in Kris Danner's car, produced these curves (in his car with the SVO intake & heads):




these cams are 222/222 @ 0.050", 0.49"/0.49" lift, on a 112* LSA, IIRC


weird.....it been almost a year since i bought them, and almost 9 months since i put them in along with the PI heads, and i still dont know how much power i make 'cause im about to put on a good exhaust...finally.....lol
 

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the VT stage 2 looks like a forced induction cam
 

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the VT stage 2 would be a very rough idle i belive. 108 would be some major overlap with alot of blow-by. I would go with a cam that has 113-114 lsa. Will this car see the street?
 

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ok n/m u just typed the duration wrong.....on the VT stage 2 it should be 225/235 @.050 duration
 

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Discussion Starter · #6 ·
Sorry about the Typo, fixed now :)

This car will see the highway atleast twice a week. I'm not worried about gas mileage. If it gets too bad, I'll get a 95 as a daily driver.

Guitar Maestro, do you think you'll have dyno results any time soon? Your cams sound interesting, but the heads of the PI motor won't have nearly as good flow, or intake to exhast flow ratio.

so I take it the 108 LSA is probably too tight for my application. I don't want to put the powerband way out of reach of my engine's critical speed.
 

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actually yes....soon as my income tax comes in, im getting a true dual 2.5" exhaust with dual X-pipes and no mufflers (just straight pipes out back), and then im off to the local dynojet.....i should have results by the 2nd week of Feb at the latest...if i break 250 rwhp i'll be happy....lol
 

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just wondered how much drop will be in gas mileage with these kind of non stock cams.
 

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Casper said:
just wondered how much drop will be in gas mileage with these kind of non stock cams.

not much. i got 16ish in town. i got about 18-20 without them.
 

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but you got 3.73s, and that alleviates a lot of load from the engine......the lower the [numerical] gear ratio in the pumpkin, the harder the engine is gonna have to work in the low RPMs due to less torque multiplication, thus lower fuel economy
 

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If you not going to get ported heads in the future, I'd suggest a Hi Tech 2060 cam.

There are a lot of differing views on how to design a camshaft, but I've come to the conclusion that LSA is a good spec for describing a cam, but not for choosing one.
 

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Discussion Starter · #13 ·
GreenBird said:
If you not going to get ported heads in the future, I'd suggest a Hi Tech 2060 cam.

There are a lot of differing views on how to design a camshaft, but I've come to the conclusion that LSA is a good spec for describing a cam, but not for choosing one.
You are correct, I'm not going to be porting the heads, or forging the bottom end of this motor. I did a google search, and a search on Modular Depot for "Hi Tech 2060", but yielded no useful results. Does the manufacturer of those cams go by a different name, or am I sucking at searching today?
 

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Discussion Starter · #14 ·
I'm kindof thinking out loud here, but feel free to make corrections to my thought process -- I'm here to learn, not preach!

Those SVO heads and those cams put out very good numbers -- I'm thinking that has to do with how well the specs of the cam are matched to the head.

Here is the head flow data I have on some ported SVO heads (Quite possibly those very heads if memory serves me correctly):
{Intake} (total = 1048)
.100....59
.200...123
.300...176
.400...209
.500...235
.600...246
{Exhaust} (total = 749)
.100....49
.200....92
.300...126
.400...148
.500...165
.600...169

From what I've been told, for Naturally aspirated applications, its good to have a 75% exhaust to intake flow ratio. Quite possibly to increase the exhaust's exit velocity and suck more air into the engine.

Guitar Maestro, you said those cams are 222/222 @ 0.050", 0.49"/0.49" lift, on a 112* LSA. With the existing flow of those heads being very close to a 75% ratio, a cam that was about the same lift and duration would work perfectly. I assume a 112 LSA was chosen as to not move the powercurve up too far, and have good vacuum off of idle. I'm not quite sure why only .49" lift was chosen. Possibly not to tax the valve springs as much? Even at .49" lift, the heads flow at about a 72% ratio.

Now, here's the problem. PI heads don't flow with such pretty numbers --
{Intake} (738)
.100....50
.200....93
.300...126
.400...148
.500...158
.600...163
{exhaust} (676)
.100....48
.200....91
.300...117
.400...134
.500...141
.600...145

676/738 = 91%. If my theory is correct, this is way high to be a good head for a naturally aspirated engine. I'm hoping to make up for it a little bit with the cams. Logically, I would want to make the intake flow a lot better, and the exhaust flow only slightly better.

From the flow data, it looks like I need something with at least 500 lift, if not a little more just to squeeze out some more power. Does anyone have any idea how much lift I can safely produce?

Now, down to the cam choices -- Lets start with the crowers:

Crower Stage 2, low lift N/A:
ADV Duration: 266 / 270
.050 Duration: 220 / 224
Advertised lift: .532 / .532

Crower stage 2, high lift N/A:
ADV Duration: 268 / 272
.050 Duration: 224 / 228
Advertised lift: 559 / .570

I think I would possibly benefit from the extra lift of the stage 2 cams, as well as the duration being closer togeather (even tough both cams favor the exhaust side of things). I'm just worried that a high lift cam would put the powerband well out of reach for my 6000rpm limit.

My problem is that I can't tell what RPMs these cams are going to put the power. Peak horsepower is irrelevant when it comes to actually going fast. I need to have a good deal of usable power.
 

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Silenced said:
From what I've been told, for Naturally aspirated applications, its good to have a 75% exhaust to intake flow ratio. Quite possibly to increase the exhaust's exit velocity and suck more air into the engine.

That is because it is easier to empty a cylinder than to fill it. 75% is assuming the cam is ground the same for both intake and exhaust.

LSA from what I learned - assuming N/A street stuff - narrower works better with headers, wider works better with manifolds all else being equal. The extra overlap doesn't help if the exhaust is restricted.

You are correct with what you see on the intake to exhaust flow issues with the PI heads. I would like to see a larger intake spec compared to the exhaust for the cam myself as well.
 

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I mean I don't pick a spec for LSA like a lot of people do, I pick valve events and the LSA is picked for me.

Silenced said:
You are correct, I'm not going to be porting the heads, or forging the bottom end of this motor. I did a google search, and a search on Modular Depot for "Hi Tech 2060", but yielded no useful results. Does the manufacturer of those cams go by a different name, or am I sucking at searching today?
There are tons of companies called Hitech, and Hitech's site is getting overhauled right now. Hitech

Specs on the 2060:
230/224
0.550/0.500
@112
 

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Discussion Starter · #17 ·
<3 Greenbird! :bowdown: Those specs sound great! Thanks!!
 
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