FastWhiteTA

Disclaimer: This is not a "what cam is good for me" post, as I already have a cam that I am very happy with... with that said...


As we know the exhaust on an LT1 head is a pretty big restriction, hence all the cams having much larger exhaust duration than intake. The question here is...what advanrages would there be to custom grinding a cam to extreme specs, say a
220/244 .510/.540 @ 114 lsa (#s on 1.5 rockers). That is kind of a combo of the CC305 and CC306, or something like that. Makes me wonder if the cam would have the powerband of a 305 (2000-6000), but able to produce more power than the normal 305 cam due to the bigger exhaust duration and lift. Seems this cam would be not quite as mean as the 306 and would be more emissions and driver friendly, but able to make more power than most cams w/ similar intake set ups. What are some other extreme specs that come to mind that might work in a setup like that? I would think this would probably make an awesome power adder cam. Are there overlap problems with a difference this large in the two durations? I'd like to see some cool ideas or interjections on this that anyone might have.

FastWhiteTA

No replies? That's kind of surprising.

my94blackz

Might be way off topic but how bout diff size rocker on the exaust side?

FastWhiteTA

It's possible, I've seen that done I think on power adder cars. But that just increases the lift, I'm also curious about the extended duration as well as the higher lift..

SVT Killer LV

the cc306 was designed specifically for the lt1, thats why it has a 14* difference in duration between the i/e. There's alot more to it than just giving it a whole bunch of exhaust duration. For instance for a typical ported LT1 head you will see in the area of 260/200 (no i know much more/better numbers can be achieved, but for comparisons sake lets stick to that) now that head gets about 77% of its exhaust flow (200/260=.769....) so you figure that a cam that duration numbers get close to that would be optimal. so say a cam such as the cc306, where it has a 230/244 .540/.576... by mathematical processes that cam lands in the efficiency area of the heads (at the time it was produced).

Now the 306 has a ton of extra exhaust duration and lift to overcome that 77% obstacle (77 percent is pretty good). So why not add a ton more exhaust duration. As with anything, too much of anything can be bad. What happens when you add too much exhaust, is bleed off, where air that is coming in is leaked out the exhaust there for eliminating the point of the cam (getting more air in).

So what is BEST to do is if you are going to get heads/cam. Plan your goals out. Get the heads first. Find out how they perform, aka get some HARD numbers on them. so you know what they flow and where they flow at. Then have you cam designed around your heads. This will yield the best results horsepower more efficiently than just spending a buttload of money on off the shelf parts and *hoping they work together.* Which if you have done h/c/i swaps you know exactly what I am talking about.

You will notice that all these "custom grind cams" from guys that really know their **** guys that eat breath and **** cams get greater than or equal to hp with SMALLER cams and way better torque numbers than the shelf cams.

FWIW, my buddy has a h/c/i on his 95 cobra with AFR heads, blah blah blah... the car did 300rwhp and 315/rwtq with a FMS shelf cam. He got a cam with smaller specs than his previous cam from a VERY popular custom cam guy (Ed Curtis) and made 315rwhp/332rwtq with the nothing but a cam swap. thats a solid gain of 15rwhp/17rwtq with just a cam swap. Not to mention the power cam from a smaller cam with a better torque curve, more power under the band. He saw gains of up to 25 rwhp under the curve in some areas.

SVT Killer LV

sorry about the length of my post but its a decent read i think

FastWhiteTA

Thanks, good post and info...

Pretty much answers my question...that extreme is not really feasible, due to the bleed off.

That's pretty impressive he gained that much with going to a smaller cam! I am impressed with how much you can do with custom cams. If you tailor them just for your heads, they get the most out of them. I remember once a while back a guy got almost 450 rwhp out of his stock bottom end LT1. Not bad, pretty impressive. But I also remember he bought a set of AFRs and had them ported, then got a good custom cam from a well known guy. I don't know the specs on any of his set up, but it's pretty impressive what they did.

OldSStroker

Very well said, SVT. I didn't think itwas too long.

It can't be stressed enough that a cam has to be fit to the engine's airflow capacity (from air inlet to tailpipes) and intended use if you want anywhere near maximum performance.

rskrause

Yes, and most aftermarket "street" cams are too big. People are impressed by size!

Rich Krause

got_hp?

its all girls fault.

rskrause

NightTrain66

The more that you learn about cams, the more you realize that you do not know.

I am smart enough on cams to know that I will pay Bret Bauer or Joe Overton to do my cams. These guys will analyze EVERYTHING and make sure that the cam is working like it should.

Lloyd

NightTrain66

SVT Killer LV

exactly right Lloyd

OldSStroker

Yes! You can always tell people your cam is bigger than it really is, especially if the duration or lobe number isn't marked on it. Well, not on this forum..nobody fibs here.

marshall93z

i was always told that the 304,305, and 306 were not made for lt1's, but carbed motors instead.