Originally Posted by Sport Side

HP will peak at 62-6400 rpm just like most all Gen IIIs do w/ the ls1/ls6/truck intake manifolds. It's enough cam to be shifted at 7600rpm but, you'd have no power at this point because of the supporting parts.

See, I can make a 220/220 110 profile peak at 6200 rpm. The same rpm that this 233/239 grind will. The only thing is, the 220/220 profile will make more torque from launch until 5000 rpm giving it the acceleration a truck will need. Where do you get that quick e.t.? From the 60'. You can make up ground by lower gears and more stall but, why not use a proper camshaft. If fbody guys can use these ported 5.3 heads on a larger bore engine with bigger cams and make 450+ at the wheels I dont see why these same heads wouldnt be able to support this cam on a smaller bore.



Again, they have the supporting parts to do so. Damn the long runner EFI intake manifolds.



I think Ed Curtis sums it up very well with this post: https://ls1tech.com/forums/showpost....0&postcount=29

Originally Posted by 02sierraz71_5.3

as long as hes got some ported 5.3 heads this thing should scream Id be looking at heads that really ramp up in cfm toward the end where as some flow great in the mid range Id be looking to sacrifice mid flow for the .600 should help keep velocity up at lower rpms and get out of the hole

Originally Posted by CStraub

Hmmmm, got a good flowing head, then you don't need alot of camshaft.. . .boy does that sound familar.

Originally Posted by CStraub

Big cam + Big heads = high rpm narrow powerband application. Unless this is a full blown Comp car, your just wasting your money.

Originally Posted by Sport Side

Next in line...We have Chris Straub.





What he told me a couple times is your looking to fill the cylinder. You put a big camshaft in the motor to reach your power/rpm goals. When you add flow thru the cylinder head, you don't need as much camshaft.

Read thru the thread I listed earlier... the whole thing. You'll come out feelin' like a million bucks.

Originally Posted by Buddy Rawls

IT really has nothing to do with theories and streetability and shifting torque...yada.

It is a function of displaced cylinder volume at the given rpms, and how big the door is entering or leaving the cylinder. Plain and simple for a given amount of displaced volume, the larger the door, the smaller the overall time is needed to move the displaced into or out of the cylinder. Throw in some lag issues and some dynamic stuff and thats the major part of it. Not a lot of subjectivity to it.

On a restricted flow motor you will need a lot of valve activity to fill the cylinder, but you cant extend the seat events too far or you loose the ability to generate good cylinder pressure due to late of an intake closing, paired up with over extending the usbale flow cross-section of the inlet path. so you will see real high ramp rates. as in the 2 barrel restricted oval track stuff, or stock eliminator type set-ups. On large crosssection inlets and or exhaust, for a given CID and rpm, you will need less overall time for the cylinder to fill or expell.

But you cant group it into particulars, you have to view it from the standpoint of IO,IC, EO, EC. this is the precise reason that valve events (cams) are so personalized to the particular combo and why global associativities of duration and LSA are pretty much meaningless. unless all motors in existences had same bottom end geometry, same rpms, same inlet and exhaust parameters.

Engine talk always centers around the numbers, but really everything is happening in units of time. ITs all flow. Displaced volume over a unit of time, is guess what? Cubic feet per minute, We see that term all the time. The only problem is, it is normally associated at the inlet or exhaust path, as opposed the cylinder volume itself.

Originally Posted by Sport Side

This is where you are wrong. Look at it this way.
2 + 2 = 4
Four is our goal power/rpm. 2 and 2 being the head flow and the other being the camshaft.
Shitty head and big cam: 0 + 4 = 4
AFR 205s and regular sized camshaft: 2 + 2 = 4


Big heads + Big cam = dyno queen.
If you don't believe it, go look at the dyno section at tech. Do some of those dynos not impress you? If they all do, you need to try and rethink what an ideal torque curve looks like.


Me. All day. I'll accelerate off the line and finish before you do. You'll trap higher than me and probably kill me in a 60-150mph street race tho.


This is the point. Matching it. When it's really matched, you need less of one to reach your goal.

Originally Posted by 02sierraz71_5.3

as far as out accelerating this is where a 4k stall comes into play if we were running the stock stall this would be true. but, Id be leaving the line at 3500 rpms and shifting at 7500. Youd be leaving at 2k and shifting at 6200. I would have more power off the line this is why dragsters are setup the way they are plus I would be moving through the rpms alot quicker and gaining alot more gross power especially with some big gears.

Originally Posted by Sport Side

I'm following you. But, lets make it a fair comparison. A matched up, small setup vs. a larger one. The small setup can compete with the larger one because the "matched" components take different aspects of the setup into consideration. We call it small but, really it is the better setup. The guys who preach this stuff prove it over and over again. Even guys like Bryan @ PCM4LESS will give you the scoop on how this works.

Point being tho, a 233/239 113 profile is a waste of lobe for a 5.3L limited to a 6200rpm peak. I'll take an efficient set of heads, small cam, 3200 tc, 4.10 gears, and compete with an overcammed setup that can hardly get a vacuum signal. I've seen it done on tech. These setups get less publicity because they are "streetable." They're out there however.