CAMS

[ethelkilledfred]

I'm a big fan of cheap cams. Cheaper the better cause I can buy 2-3 cams for the price of one major brand cam, giving me the ability to swap several cams in the car to get a more refined choice.
 This is my wifes Camaro with a budget cam that cost less than $60.

http://www.youtube.com/watch?v=Su1xU20F8cs



I also take stock cams and get them reground or buy obsolete swap meet cams and get them reground between $30-$60 depending who does it.   

This is just a small pic of some of the cams I have to work with plus the ones that are in some motors I have.


Now I use single pattern cams and dual pattern cams and each works according to the application. My view on cams is the better the heads the less cam it needs to make power, the worse the heads the more cam it needs.

What do you run and what are your thoughts.


BTW Tuff, here is one for you, there is some school of thought in having more intake duration than exhaust. Have not tried it and don't remember the specifics on why it's done and how much benefit if any comes from it. 

[TDtuffnuff]

Now I use single pattern cams and dual pattern cams and each works according to the application. My view on cams is the better the heads the less cam it needs to make power, the worse the heads the more cam it needs.

What do you run and what are your thoughts.


BTW Tuff, here is one for you, there is some school of thought in having more intake duration than exhaust. Have not tried it and don't remember the specifics on why it's done and how much benefit if any comes from it.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

I agree on using both types of cams which compliment the individual build parameters.,. in the early days we had Crower Monarch, Sig Erson Viking, several Engle, Melling, Chet Herbert and the likes of Isky Super Le Gerra single pattern cams.
We made tremendous power with all, but each choice took a tremendous amount of tuning and the MPH on the time slip was our best guide then.,. in fact it still is, if the bite is there.
Gradually dual pattern cams came on the scene and guys were winning.,. hmmm, this is because we had early iron heads and the split pattern compensated for the so-so exhaust flow and really wakes up an old school engine with 461, 462, 292 and similar small chamber heads, in ported or unported form.
Now, single pattern cams are making a come back.,. because we have modern fast burn alloy heads, factory flow ported, huge runners, excellent chamber design and Cathedral ports, that outflow anything ancient, bar non. 
On the duration thing, it all depends on optimum flow for the desired RPM range where maximum power is required, again the MPH dictates what works best.,. a seat of the pants feeling or a few dyno pulls mean nothing, but the time slip means everything.
On the cam choice, I'm like you and my bud at Kershaw Performance and use what I have, or get a profile I like ground on a stock one, then get it parkerized and use it.
I did this a few times by grinding a Chevy profile on an AMC cam.,. the little 304 sounded like a 302 Bow Tie.
The longer duration on the intake, is because the intake charge is totally dependent on atmospheric pressure (14.7 lbs @ sea level) and the low negative pressure area, created in the cylinder, on the down stroke of the piston on the intake stroke.,. this flow is very s l o w ( less than 1/2 velocity) in comparison to the exhaust fow.
The high pressure exhaust, by comparison, is forced out by the upcoming piston on the exhaust cycle and enters atmospheric pressure.,. at more than 760 MPH (sound barrier).,. the noise, with open headers, is the exhaust, breaking the barrier.
Thanks for the topic EKF

:)

[larrym]

How does does the single and dual pattern cams affect a turbo charged application. Some threads I have read like a little more lift and duration on the exhaust side to help spool the turbo.

[TDtuffnuff]

Yes, turbo applications benefit from a longer (or more lift) exhaust exhaust cycle so the volute spools up faster.,. a boost engine is also not overly sesitive to valve size, since we are dealing with positive pressure and not atmospheric.

:)

[larrym]

I can confirm from my experiance that with a turbo application if you are going to spend money on head work spend the exhaust side, with just having the exhaust bowels hogged out and mild port work I saw some big improvements. Managed the time time in my slip (my dyno runs prior to the head work netted 370 hp and 351 ftlbs. I added new springs to these heads which I'm sure helped also.

[buckola]

So a stock intake valve works fine/best on a forced air engine??

[larrym]

Depends on the application I guess mine was a 3.8 and I kept the stock valves just had them back cut.
From what I have read in the Buick applications you need to be shooting for the 10's before a larger Valve on the intake side will net much improvement we are forcing the air in. Remember we don't spin these little motors past about 5800 rpm.
Mine peaks at about 5500.

[TDtuffnuff]

Engines with mild boost fare well with stock valves, since the intake charge is pressurized.,. At 14.7 pounds boost, the engine displacement doubles.,. so at 7.4 pounds, add 50% to displacement.

:)

[PENSIONER]

At 14.7 pounds boost, the engine displacement doubles.,. so at 7.4 pounds, add 50% to displacement.

WTF -you v8 guys.How do you get the boost that low.LOLlol.
I run 22lbs on the street.
?? If at 1 bar your ci doubles at 2 bar does your ci triple or quadruple

[buckola]

 

[TDtuffnuff]

At 14.7 pounds boost, the engine displacement doubles.,. so at 7.4 pounds, add 50% to displacement.

WTF -you v8 guys.How do you get the boost that low.LOLlol.
I run 22lbs on the street.
?? If at 1 bar your ci doubles at 2 bar does your ci triple or quadruple

You seem to know a lot about boost Pensioner.,. how much do you run.
I'm assuming you have a turbo, or a Roots?
I'm curious

:)

[larrym]

Its another 11 second 6 banger   sorry to hyjack the thread maybe I should start a forced induction thread.

[TDtuffnuff]

No biggie, post away Larry

:)

[R/T kota]

Its another 11 second 6 banger 

I think that might be a conservative number this year

[redneckjoe69]

sounds like alot of you guys on here are into turbo v-6's.