Cam Duration Vs Lift

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Petzschler

Petzschler

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simple question really...

which of these hypothetical cam profiles will make more usable horsepower and why?

290° advertised/ 240° @ .050" duration/ .475" valve lift/ 113°lsa
or
270° advertised/ 220° @ .050" duration/ .525" valve lift/ 113°lsa
 
first one. 2nd cam should have a lot better low end power
 
I can't answer that one unless I have a host of questions answered myself. LOL

Useable in what arena? Along with car weight, engine size, converter stall, rear gears. Assume the rest of the car is a stock as a rock Dart.

The game changes.
 
The 1st sounds like a hyd, while the 2nd sounds like a solid with the more lift to make up for some HP of less duration, but to me they are the same really.
does the lift outweigh the dur in HP?
Useable in what, with what?
 
400 cid engine
10:1 comp ratio
280 cfm at .500" lift intake
220 cfm at .500" lift exaust
1 7/8" headers
single plane intake
750dp holley
symetrical lobes

i made the cfm and c/r to work very well with either cam profile haha.

cam is solid if that matters. its on an engine dyno. been alot talk about these new high lift/short duration cams.
I think its all snake oil... so just looking for opinions.
 
I'll vote 290 with the 3.38 stroke engine.
 
Both solid cams? I'll take the 290 too. 20 degrees is a big number between the two and the effective duration would only be about 210-212 on the small cam and 230-232 on the larger one. Great torque and really smooth idle on the smaller one, but only till about 4800-5000 rpm on that big of an engine. Good truck cam. In a car I'd definetly go with the larger cam with the right TC and gearing.
 
Too many variables still,what do the heads flow at .400 ect.,also are the durations/lifts firgured with lash or without.Ive never seen a solid off the shelf with duration that small with that much lift or one with that much duration and that little of lift-and whats with a 113 lobe seperation?,those are not average grinds.A 113 spreads the power upstairs and if the heads are flowing considerably less at lower lifts then the big cam aint doin much good with the lack of lift so the small cam may actually make power in a more usable range depending on the combo,but the duration of the big cam helps to crutch the lack of lift/flow-kind of a wash but like I said alot of variables lol.
 
intake flow:
.100" 170cfm
.200" 190cfm
.300" 220cfm
.400" 250cfm
.450" 265cfm
.500" 280cfm
.550" 260cfm
.600" 210 cfm

exaust flow:
.100" 100cfm
.200" 150cfm
.300" 180cfm
.400" 200cfm
.450" 215cfm
.500" 220cfm
.550" 220cfm
.600" 220cfm

lash is 30/30
if it matters.. dynamic compression would be around 8.5:1
 
.525 cam, with more duration would be cool,like 238*@.050 282*adv

but between the 2 you get more time/dur opening with the the .475 290*/240*@.050=cyl fill
not to divert,
I recommend something like 110cl .530 lift 238*@.050 285*duration
 
360Z28 said:
intake flow:
.100" 170cfm
.200" 190cfm
.300" 220cfm
.400" 250cfm
.450" 265cfm
.500" 280cfm
.550" 260cfm
.600" 210 cfm

exaust flow:
.100" 100cfm
.200" 150cfm
.300" 180cfm
.400" 200cfm
.450" 215cfm
.500" 220cfm
.550" 220cfm
.600" 220cfm

lash is 30/30
if it matters.. dynamic compression would be around 8.5:1
Click to expand...

Not too sound redundant but is that lash already figured in the cam specs?-alot of the modern high rate of lift solid cams are already figuring lash in their specs,thats a big difference.Which cam is the dynamic figured with?,lol more questions than answers,are you actually going to have real world results between the two?,kinda fun to pass time.
 
both cam are ground with those lash numbers in mind. this is just a hypothetical cam we're talking about here.

was looking at some master lists from UltraDynes website for ideas. lots of those cam specs are not in any production
cams

really world? eventually. its no biggie to get a cam made. but if i was gonna spend that kinda coin it'll be for a hyd.roller built
to the info I can get here and from my experiance.

i would like a cam that had fast closing intake ramps, and late closing exaust ramps. 110°lsa .600"+ lift range. exaust lift would
be -.020" of the intake lift. just basing that for the fact the most exaust ports peak relativly early. durations around 240° @ .050"
and an advertised of 290°

1wild&crazyguy,
Thats a interesting profile you came up with. is that an imagination cam or a production one?
I got an old MP cheater cam with 306° ad.dur./ 260° @ .050"/ .465" lift i think. power range
must be from 6100-7000rpm lol.
 
I like that... 'imagination cam'... ha ha, right on

Really I was just coming up with something in the realm of the 2 cams you mention but what I feel is a better grind for the heads/combo.

It's a spin off of something along the lines, like the cam in my stroker, I know what I wanna run but am grounded by the actual compression ratio.

If you check engle cams site and look at the K60 it's a fast ramp thats close to your taste, which is on a 108*cl originally, so in order to widen the cl some lift has to come off and well...I feel it would be to the advantage with those head flow #'s to be a lil above peak flow/lift to fatten opening cycle flow=early fill and still stay in the best of both worlds kind of duration #'s.
 
this one from engle seems pretty kick ***:
Part #: 2306-V
Grind #: KV-6
Int. 612" Ex. 612"/Int. 301° Ex. 301°/Int. @ .050" 272° Ex. @ .050" 272°/108°

this is the one from UltraDyne looks to be almost god like lol:
Grind #: R93
Int. .611" Ex. .611"/ Int. 304° Ex. 304°/ Int. Dur @ .050" 268° Ex.Dur @ .050" 268°/ 110° lsa
 
First Cam \\\ Why?

Heads Low Lift #s \\\ Heads Are Dead After .500 Lift
 
First Cam Needs 255 @ 50 And .500 Lift
If The Cars Heavy Lower The Center Line.
LOTS OF GEAR AND A BIG TIRE
AND YES SNAKE OIL IS STILL SOLD.
 
This is a small block 400?

Neither of these cams are going to work very well.
As was pointed out, your flow falls off after .500" lift so opening the valves much further does nothing but slow down the cylinder fill and add stress to the valvetrain. With that said, .525" is not really a problem with your heads because it is only open that far for a very small part of the duration.
The 290 duration cam will make more power on top while the 270 cam will have more bottom. I would rather see the 290/240 @.050" duration with the .525" lift.
I don't have all that much experience with these "new" cam grinders but I do know that Clay Smith will give you what you need at a fair price. These guys have been in business for about 80 years and they virtually invented the custom hand ground cam. If you tell George your vehicle info and your wants/expectations, they will grind you a cam that will give you what you want. The C-304-6-B (solid cam for SBM) is 308 adv./258 @.050" lift, .525" and makes big power on a 340 from 2800 on up to around 7000 rpm. In a 400CI engine that same cam will make power at a little bit lower rpm. Obviously, you would need at least 3.91/1 gears to use this cam, but it's just an example.
The cheater cam you listed would start pulling at about 3000RPM and keep pulling to around 6800RPM. It would work great with your setup, but you may benefit from 1.6 ratio rockers...since the lift is a bit short of your peak flow numbers.
You are kicking around lift numbers that would make your engine run like crap. If you try to run lift numbers above around .525", it will not run good at all.
T67 nailed it! Those numbers that he suggested are very similar to the Clay Smith cam that I have.

I still don't know what you mean by "usable power". To me, usable power on the street is power under the curve...a wide power band that starts fairly low in the RPM range. Usable power on the dragstrip is a little different, since you are going to be at wide open throttle for pretty much the whole time.

e-mail: [email protected]
or phone (714) 523-0530
Monday - Thursday: 9am to 6:30pm

P.S. IMHO, running a hydraulic roller in a motor with heads that do not flow above .500" is just a waste of money and a step backwards. The solid flat tappet cam will outperform the hyd and the hyd roller cam at this level.
 
oh i dunno.. theres a dude running around with a 416" with a solid roller .630" lift engine. looks very stock, right
down to the intake and exhaust manifolds and T/A heads. pushes over 420rwhp. thats with an A-833 and 4.10's.
i promise you those heads don't flow worth a crap over .550".

you see hyd. rollers in everything now, doubt very much those heads flow anything over .420ish lol. for example, my
89 ranger 2.3l has a hyd.roller in it. prolly around a .390"lift.. no way it would get the advertised 120hp and 30mpg without it.
step foward in that case.

T67 nailed it eh? what do centerlines and car weight have to do with eachother? I assume he meant heavy car= more
needed horsepower so decrease the centerline? well that'll move the powerband up thats for sure.more hp. prolly loose
some torque in the proccess. whereas advancing the cam you'll gain bottom end.. but alot of the air/fuel charge is lost right
out the exhaust, making the engine less efficient. old trick, if you advance/retard the cam more then 4° and it still
pulls, time to step down/up to a different cam.

that cheater cam i mentioned, no way in hell you'll get that streetable. that thing needs a 4000+stall and 4.56+ gears.
and thats just to move lol. that thing pulls hard to 7000grand! honest!

as far as usuable horsepower, yup that would be under the curve. no sence in making power from 6100-7000rpm only.

the trick here I think is to get the most lift and lsa while at the same time keeping the centerline and duration @ .050"
within reason. solid and hydraulic flat tappets for the most part can't do that. hence the roller cam setup. thats the
ticket.

1wild&crazyguy said:
As it unfolds....ha ha

those are great, at that level.

So what have gotten from this so far?
Click to expand...
alot more the what I learned from watching Captain Kangaroo on saturday mornings as a kid LOL.
 
What stroke is this? The usual 4" small block? Sorry if I didnt see that in my read. What is this going in again? What are you doing with it?

On that KV-6... IIRC I used a similar if not that lobe for the exh lobe on a custom Engle solid flat tappet in a 505" I built two years ago. The intake lobe was the same family but something like [email protected]...
 
Well, 360Z28, I guess you have it all figured out! You are aware that you can get an even bigger cam, right? Why stop at .630"? I'm glad you are such an expert. I have no idea why you are on this site asking for advice. Gee, what diameter are the pushrods in your 89 Ranger 2.3?

johnnycashflipsyouoff.jpg
 
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