SS MPSTR

...and back asking the questions you avoid. You can talk the talk, but do you walk the walk? We're still waiting for you to post up results to support your self-proclaimed internet engine/cam design prowess.

And the older guys/cam companies 'in the dark'? That's laughable - what do you know that hasn't already been known? What can the Big Bert Racing Engine regime contribute to the countless dollars, thousands of hours of R&D and racing results these other guys/cam companies have? This should be interesting - enlighten us.

OldSStroker

Probably no "enlightenment" forthcoming, STR. You know the old saying from your CIA days, right? "If they tell you they would have to shoot you."

SStrokerAce

Hmmmm

Lisa33(Non 4th Gen)
383LT1, maxed out procharger F1, LE ported TFS heads, Bret Bauer cam, half filled block, JW PG, 8 3/4 3.91 rear end, 12.5x30-15 slicks
60 ft.:1.25
1/8:5.42@128.6
1/4: 8.54@151.6

I guess 2nd fastest LT1 doesn't count? I tought on here it would at least. Then again what do I know I just swtiched him from a emissions legal cam of mine to a tight LSA hyd roller blower grind and picked up 80hp.

Either way everytime YOU bring me up on forums it just free advertising.

Bret

thesoundandthefury

You have two options:

1. You can tell me that I'm wrong, followed by an explanation why.

2. Keep your knowledge of why I'm wrong secret, but remain silent.

Pick one.

SStrokerAce

LOL nice,

It's not the overlap that is the ONLY killer of low end TQ. If you open the exhaust too early or close the intake to late then you will be out TQ in the lower RPM just as well. Overlap can kill TQ, but only if there is too much of it, problem is what really should be looked at is the average tq/hp in the RPM range and the combination of overlap and duration to get there.

I don't like talking in overlap though, since the amount that a motor can handle doesn't just depend on RPM range, displacement etc... it's mostly a function of pressure waves from the intake manifold. If you have longer runners like a LS motor than the overlap isin't as much because the pressure waves are stronger, than something like a LT motor with short runners that give more lower amplitude pressure waves.

Is that the ONE you wanted?

Bret

OldSStroker

Actually, expressing an opininon on someone's ideas and their merits is called freedom of speech. That is another option. You know from whence it originates. Justification of a position is not required by that Ammendment. Neat country, the USA!

Well, on some forums freedom of speech is not tolerated from everyone. This forum allows all of us a "long leash", which is refreshing.

It's good that posters like SS MPSTR and SS RRR can say anything they want on this forum. We all get to judge the merit of their posts ourselves.

I may dislike some of the things people say, but I will (and have) defend their right to say them.

Freedom of speech is a double-edged sword. Mark Twain had a good comment on that about a century ago (when I was just a kid).

"It is better to keep your mouth closed and let people think you are a fool than to open it and remove all doubt." --M. Twain

thesoundandthefury

That's all well and good, but the basis for my statement was this:

Sure, you could make any cam "lope like hell" with the right combination of LSA and duration and still arrive at your target HP/TQ goals, but at the consequence of not being able to control where at in the RPM range you want your peak to occur. The OP said he wanted a cam that lopes like a CC306 but doesn't want to shift higher than 6,200rpm: two variables that are impossible to reconcile WRT how much overlap would be required to attain either.

You can't have your cake and eat it too.

thesoundandthefury

Why do I suddenly get the feeling I'm being ambushed?

I agree wholeheartedly about freedom of speech, however, the rub comes when you express your opinion about somebody's ideas but then turn around and expect to be granted the luxury of being considered credible without having to do anything to show it.

SStrokerAce

Actually no, why do you think that overlap controls any sort of peaks? Sounds like too much LS1"tech" reading nonsense to me, the world doesn't work that way.

A cams overlap doesn't control the timing of the HP or TQ peak in the RPM range. That's just not the case, and if you think so you really need to look harder at your variables here. I pretty much TOLD you what you needed to look at, and you write it off like it's a lie?

The truth is that HP/TQ peaks are governed more by the induction and exhaust tuining lengths and cross sections. The amplitude and length of the wavelengths and how frequently they occur at a RPM have more to do with the increase in cylinder filling at TQ peak than the amount of overlap that is there. The HP peak is just the mathematical equation of rate of TQ drop relative to RPM. The amount of overlap can either work with them or not, which is one of the keys to making a camshaft work. The overlap that works in a RPM range is going to be ruled by the strength of the harmonic which is a function of the length of the intake runner. Your not going to read that in any magazine, so I'm sorry I can't give you "proof" in anything you can read in the next 10mins on the crapper.

What you are saying is if you have the overlap area of a cc-306 then you WILL have a HP peak that is over 6200rpm reguarless of the duration. I REALLY think you are missing the point of how duration and overlap are linked, and what happens to the EVO and IVC in that instance.

You might not think you can have a HP peak and TQ curve that works well with shift points before 6200rpm AND have a nasty idle. I on the other hand, know how to do it, because I've done it many times on LT and SBC motors. This isin't internet BS from some ramblings of a LS1tech profit, it's actual real deal results.

Either way good luck with getting out of that box you live in. If you want to really know the truth put down the mouse and go get one of Prof Blair's books on 4 stroke engines, it will take you a while but you WILL learn how the world works then.

Bret

PS: "expect to be granted the luxury of being considered credible without having to do anything to show it." Don't call the kettle black when your the whole set of pots sitting there yourself. BTW did I say how much I love Mark Twain.

OldSStroker

Ambushed with more information, perhaps?

Here's the link you need for the Blair text book mentioned:

http://www.motolit.com/desandsimoff.html

Here's the precis:

"Provides assistance with the actual mechanical design of an engine in which the gas and fluid mechanics, thermodynamics, and combustion have been optimized so as to provide the required performance characteristics such as power, torque, fuel consumption, or noise emission. The seven chapters start with the fundamentals of engine design and development. Other topics include unsteady gas dynamics, intake ramming, exhaust system tuning, design of porting and valving of the cylinder head, and the measurement and analysis of the discharge coefficients of ports, valves, and ducting discontinuities. Blair was associated with Queen's U. in Belfast for 32 years."

It ain't no ten minute (nor ten hour) bathroom read, especially if you want to understand it, but digested in small doses (pardon the play on words) it goes a long way toward explaining how engines see the world. There are many empirical engine examples which reinforce the theoretical and calculated results. It's up to you whether you consider Blair credible.

Shopping around will get it for about $100, or about $25 per pound.

Ironically it is even on LS1Tech's "Books 101" sticky.

thesoundandthefury

Because overlap is a product of duration, and in fact dictates it, as evidenced here by our good friend David Vizard:
http://www.popularhotrodding.com/tec...ics/index.html

The overlap triangle, comprised of duration, lift, and LSA, very much controls the "timing" of the HP/TQ peak in the RPM range.

Okay, and what exactly is the big mystery about a stock longblock LT4? I don't see the need to go down this rabbit hole of analyzing intake runner lengths and port cross sections and wave harmonics: GM did an exceedingly good job of building them all the same, so I think it might be safe to assume that we have all of those variables locked in.

No, I'm saying that:

1. A CC306's lope is directly proportional to the amount of overlap it has.
2. All else being equal, a cam's overlap is a product of the desired operating RPM range.

The OP stated that he wants a cam that lopes like a CC306, but peaks earlier. You can make that cam peak earlier by either:

1. Shortening the duration
2. Tightening the LSA

Both of which will decrease the original overlap of the CC306, and in turn, change the sound characteristics. Hence, why you can't have your cake and eat it too.

plaf713

whats going on right now?

sandman2100

Pecker Checkin' party?

Way off what the OP was after, but a good read regardless.

dangalla

lmfao, seriously

but the more they argue, the more i learn

and the more happy i am that i just ordered an le2 cam

SS MPSTR

Say anything I want? LOL. Asking for credentials is not 'saying anything I want'. I expected you to be old enough to know the difference. Posting on this board is a privilege for me as it is for you and the whole Big Bert Racing Engine corporation. Thinking that freedom of speech is granted here, or on any other board of similar nature, is as silly as the Mark Twain quotes. Trust that everyone recognizes the whole merit concept you reference is in fact a two way street.


If you claim to be the world's best at anything, you're going to get called on it.