Quote away! I gave you one from a very reputable camshaft manufacturer. Please quote reliable sources.

I'll start http://www.webcamshafts.com/pages/cam_glossary.html Bottom of the page.

Thanks

 

Wow, I think you're going to be in for a surprise.

 

Look at the "varying lobe seperation angle". It says just like the one you posted that the tighter LSA will move peak torque to a lower rpm. You know that means it can make more power up high right? There will be more force applied at the right moment which will allow MORE WORK TO BE DONE OVER THE TIME ALOTTED (More power). I will post before and after cam dyno's to show you visually.

http://www.webcamshafts.com/pages/cam_glossary.html

Edit: The faster torque can build the more force it can apply over a given amount of time. The higher the rpm goes the more power will be made with the quick rising and increased peak torque.

 

I have a feeling someones getting owned here pretty soon

 

This is pointless to keep argueing. The people who know what they are talking about... well know what they're talking about. It doesn't matter what other people say, fact is fact. We don't need to prove anything here.

 

You're right. I will admit I was wrong about the peak torque numbers. I was thinking about it in the wrong way trying to prove my point. It's easy to see, if you install a cam (A recommended grind from a reputable company such as comp) with a tighter LSA you gain both torque and horsepower, I know this, it was dumb of me to say otherwise.

Edit: Pierre let's just drop this. If you have actually installed a cam on an engine before you would be able to understand where we are coming from. I promise you are just misinterpreting what has been said. I am not saying in any way that the websites you are using as your sources are wrong.

 

What?!?!
YOU'RE OUT OF MAXIMUM PWNAGE!!!


jk we all make mistakes!

 

You seem to know quite a bit. Are you saying that I am wrong about the peak torque? I shouldn't have said what I did there and knew better. As far as everything else, I have seen it dyno proven after installing cams on many cars.

 

hmmmmm, depending on your numbers witt i may want this mod, or will adversly effect auto x performance?

 

Haha I know. I just got MAXIMUM PWNED!

Anyways, here's an example. There are more mods than just a camshaft, but you can see the change in the powerband. You can see that as the torque peaked it created more horsepower.:

[IMG][/IMG]

 

That thing would prolly continue to build power for another 500-1000 rpm. Good find

 

I'm OK with droping it although I think it's a very interesting subject. I generaly avoid pissing contests as they serve no purpose. There does seem to be a fair amount of conflicting information on this subject and I'd like to look into it a little more carefully.

Why would you think I've never installed a cam before? I was active for years in Nascar modifieds up here in New England and have put in dozens. And yes I'm perfectly comfortable degreing them in.

Unless you only change 1 thing at a time it's hardly a fair comparison. Can you be more specific about what the baseline was and what changes were made?

 

Okay, I will try to find a dyno chart with more specific information.

 

Ok, measured Dan's cams (the same as mine) to my stockers. The radius change at the greatest point was .80mm and that was on the exhaust cam. The greatest change in radius of the base circle on the intake was only .55mm.

Add in a rough figure of rocker ratio from roller to contact point of the lifter and it should be in the neighborhood of 1.40 total mm additional lash the lifter has to take up, at least somewhere in that neighborhood.

 

and thats good or bad

 

Do you have any before and after dyno results for these cams? I, like Edubs, have the JBP cams and have had nothing but problems thus far and may consider switching them out if they truely make good power.

 

this means you need those shims and were trying to get them to you ASAP. sinister is working on it as we speak. im kinda useless right now since im in the middle of the ocean.

i agree..... guys you all seem like some pretty cool folks but please know the pierre does this kind of stuff for a living. 99.9% of the time he wouldnt lead ya in the wrong direction.

 

I'm listening to him, but I think there's some sort of misunderstanding.

When you break it down really simply you have more overlap and therefore a longer period of time for the exhaust to exit the cylinder and help to pull in more intake to fill the cylinder at engine speeds where without overlap it is not possible. Check out Holley's explanations, it's very cut and dry.

What does it do?
At high engine speeds, overlap allows the rush of exhaust gasses out the exhaust valve to help pull the
fresh air/fuel mixture into the cylinder through the intake valve. Increased engine speed enhances the
effect. Increasing overlap increases top-end power and reduces low-speed power and idle quality.

http://www.holley.com/data/TechServi...0Camshafts.pdf

Edit: Another thing is that a cam with alot of overlap allows exhaust gas reversion at low engine speeds. This has the effect of EGR and does not help power. But when you increase the rpm significantly the exhaust gas speeds up to the point of putting a vacuum on the intake port when the intake valve opens during overlap. This cause a burst in power, which increases with engine speed naturally.

 

Here is some interesting info that ties my views together nicely and yes I'm quoting articals that support my view :-)


"Narrowing the lobe separation angle effectively advances the intake-valve closing point, allowing the cylinders more time to build compression as the piston rises to TDC. After regrinding the ’02 LS6 lobes onto a 112 LSA (about 5.5 degrees narrower than stock) and installing the cam with a 107-degree intake centerline, Katech’s modified LS6 cam doubles the overlap area. Narrower LSAs also tend to move the horsepower and torque peaks closer together. In theory, narrowing the LSA without altering the duration of the cam should improve low-end torque due to improved cylinder filling, moving the horsepower peak closer to the torque peak as a result of closing the intake valve sooner. Both predictions came true when we saw torque jump 13 lb-ft to 472 lb-ft at 4,800 after the cam swap with a corresponding 400-rpm drop in the horsepower peak to 466 hp at 5,600 rpm."

Taken from...http://www.hotrod.com/techarticles/1.../cam_swap.html

Pierre

 

Ok, i'll buy that actually. But, remember you can increase overlap using two different techniques. One technique is by increasing overlap without changing duration like your post demonstrates; the other technique is to change the duration of the cam. This is probably where we are having opposing views here.

Even still, I have a question; the question is not based on doubting your find but more out of curiousity. Although his HP peak shifted downward, was his cam still able to support power in the upper rpm range? Just wondering.

Good, I'm glad we figured this out. No one was right or wrong here and good information was provided to show both sides of the story.

Edit: In essence what I see from your article is that there is a way to run increased overlap without sacrificing low end power. They accomplished this by using a different intake centerline. That's cool, I never thought about it this way.

 

I can't believe you guys are still fighting about this! I thought I was the kid on this forum

 

At this point we aren't arguing we're just discussing. I see where he's coming from now, but all in all if you buy a "canned cam" with increased overlap and install it straight up it will shift the powerband upwards.

You still are

 

My basic arguement was for a, given duration and lift, cam making the LSA narrower would increse low/mid end and decrease top end. It's a given that increasing duration, keeping the same LSA, will move the power band upwards. I have absolutly no argument with that and never have.

Looking at the dyno sheets there was only a loss of 8-9 horsepower between 6,000 and 6400 and a solid 15-20+ ft #'s of torque in the low/mids for the 112 LSA grind. Good trade off I would say.

Pierre

 

Hell no! Top end FTW!!! Either way, mine will probably still be building power when it slams the 8100 rpm rev limiter

 

Noice haha.