not to argue,

I have found that head guys are not cam guys, different breed. One is the brawn of the operation and one is the brains.

The thing is the combo of lift and duration is what is important, .560 is not that high, but If you are talking about 214 deg rather than 230 it is. It takes alot of work to get the valve open that much in that little time.

Well area under the curve is important and yes at some point you have to increase duration to get more lift.

I have found that super well designed cam lobes is way more important. A fast ramp inverted flank cam with say at least .560 is where I would start. When you can get over .600 lift with 224 degrees of duration then why would you need more. Hell I use 214 degree lobes that have as much area (inch degrees) under the curve as any 238 deg solid flat tappets.

Now one last thing. The reason why the closing event on the intake is so important is because the air entering the cylinder has a momentum behind it and it also has a great amount of pressure, 5-6-7 PSI cramming it in the cylinder like a supercharger. This all happens at the end of the intakes time open, not at the begining. So opening in the valve earlier is only rpm related. I.E. the faster things are happening the less time the air has to change direction and start heading for the cylinder.

Even some of the top guys at Comp think I run too little duration in my cams, but then again it's about average power. It's out of the box thinking that finds that extra power, not the same old thoughts.

Bret

As long as I have been at it, I desprately try to get a cam design to strait up status. You almost always have to get some advance in a cam to take up the slack to make it actually run strait up.

 

Yeah phil,

i sent it to the working email address!! This is an interesting debate on camshafts. I just wanted to make 400+ rwhp and run good et's. didn't think it would get this complicated.

thomas

 

Brett, all our stuff is essentially what you described. I know what you've been saying about lifting X amt in XXX deg vs. something 10deg shorter, too & i agree . The guys I do heads with.. well one does valvetrain research & development for Evernham here in Concord, and the other builds arca/busch/cup/trans-am/etc. engines for a pretty prominent shop, and him & the owner are quite **** about designing their own lobes & having them ground how they want them. Theyre fans of some pretty mean stuff that other builders claim "is too much" (regarding ramp speeds & whatnot), but for whatever reason their stuff just about always outpowers the other guys & doesnt break an inordinate amount of parts in the process. So yeh, I'll agree on what you were saying, ... that and I'd like to point out, that from where I sit.. the .050 specs really dont tell ya a whole hell of alot about a stick without other reference points. What I've always thought anyway, after seeing ppl sit down and play with numbers & draw their own cam diagrams for custom lobes

*shrug* It's an interesting subject & online I tend to have a tough time putting my thoughts into a post that coherently conveys exactly and all that I mean. Too bad Chuck has forsaken us, he was fantastic at packing information into a coherent & brief post

 

i got lost about 2 pages a go

LPE cam's thay pass emissiom that is why the dur is so small they make all there power with lift and alot of lift to make the power?
and his car are not that fast most people are making more power with heads and cam then his stroker eng?

 

Tell me about it. .200 duration numbers tell just as much. I still think that all lobes should have a Lobe Area in Inch Degrees, that would tell us so much more.

BTW what's the shop? I know there are some really big names down there building stuff.

Ramp speeds is all physics and as long as you ahve good contacts and use the right parts breaking stuff is not going to be a problem unless they have bad parts.

It's funny, I used to be much better at talking about how I feel, and now i'm much better writing it. Still some stuff you just gotta sit down and show someone face to face.

Schurters LT1,

JPE is about having a bullit proof package that you can drive everyday. Granted I don't think that they are on the edge as much as some are, but they sell alot of stuff, have a great name and make lots of money.

His cams slide by emissions because they have very little overlap, and he makes power because of the small duation (that keeps the overlap down) and large lift (that keeps the power up!)

Bret

 

Don't get me wrong here LPE is a GOD of small block & big
and everthing you said look i don't have a clue about cam's trying to learn i am just going by what i have read and what other people are running in there cars.

YOU WIN thx for the info

 

well i'm going to throw a curve ball in here and say my cam on my 355 twin turbo motor is a 232/232 .483/.483 114LSA on a 114IC hydraulic flat tappet

 

Duration, Duration, Duration!!!! Don't you guys know that DURATION is all that matters???!!!
Hell, the cam companies know this... that's why they're selling all these less than optimal cam designs... they know you want 230º @ .050, they also know that it needs to be 'streetable'...... so they give it to you with a 112 LCA to smoothe things up and you end up with a really poor torque curve. Hmmmm, makes one wonder.

-Mindgame

 

Hello everyone. I plan on doing heads/Cam this winter and I would like to educate myself so that I can make a good cam selection. Is there any literature that I can refer to, or are you folks talking from experience. I have always been hesitant to accept items out of the box as they are always geared towards fitting the order for the general population and not working the best for any one person. I do not want to step into a shop and be steered in the wrong direction. Any recommendations would be appreciated!

Thanks,
Jason

 

You got it! They make cams with big durations because that's what sells, then they put a big ole LSA on it and take the overlap down so a guy can drive it! It sounds just like a quote Vizzard makes!

Bret

 

I thought you would want a larger exhaust lift & dur. compared to intake on turbo motor?

 

Not really . With the turbo stuff, some guys run reverse splits etc. to keep exhaust gas velocity up. That and, you really dont need to worry too much about residual cylinder pressure delaying the cylinder filling when the intake initially opens with the turbo stuff I dont think

Turbo.. mmmmmm. Still.. something more impressive about doing it NA

 

ya i agree......i was originally building a Iron Eagle 406 with a big shot plate but then i realized i wanted something streetable

and anyway....boost is more fun anyway you look at it

 

No big secret there Ace, Vizard's said it, McFarland's said it, Smokey, the list goes on.

When my buddy had VHS build an LT1 for his 66' Vette, Valley Head Service contacted Isky cams. I understand they have a pretty personal relationship with Iskenderian and speak to him directly when they call. Anyways, Isky's reccomendation was a cam with an LCA of 110. That was a far cry from the 112-114º LCA cams everyone else was recommending. I will say this though, after riding in maybe a dozen LT1/LT4 vettes (I'm in a Vette club).... his is one of the strongest LT cars I've ever been in. The torque curves for that engine are also some of the best I've seen. I guess ole Isky knows a few things too huh.

-Mindgame

 

Okay, but with all this lift, aren't you eventually going to have to increase the duration to make more power? I mean, can't you only go so far with a small cam? It sounds to me that if you were to do a heads/cam LT1 that you'd get some killer heads (who wouldn't) and a milder cam like LPE's or maybe even a 305? But is that going to get you the most power? What if you went with a 236/242 on the stock bottom end? More power, right? I am just trying to understand what you're looking for in a cam. I am only learning and at the same time trying to decide what cam I want for my 396.

One more question... So, if you were to build a daily-driver 396, how much power would you be looking to put out, and how would you go about it?

Brian