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Discussion Starter #1
For weeks now I have been debating on my cylinder heads, camshaft and intake. At this point, all I understand for the cylinder heads and the intake is to focus on the CFM flow. The cylinder heads have a certain amount of CFM flow at different increments of valve lift, and the intakes are designed to flow at a constant amount of CFM. However, how can I choose a camshaft? I would prefer something off the shelf, simply because the price is right. I know a custom camshaft may yield a significant amount of horsepower, but my project may change later - if I become more power hungry.

I used Comp Cams, but I would like to understand how to effectively choose a camshaft - at least a little understanding of lift and duration. In lamen's terms, a simple explanation of why someone would say purchase Steeda 18 rather than FRPP X303. How do these camshaft specs equate to understanding the best combination for a certain set of cylinder heads and intake?

I am debating whether to purchase a Trick Flow kit or seek a cheaper solution using FRPP GT40X (since they are priced EXTREMELY cheap at Jegs).
 

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Choosing a Cam

For weeks now I have been debating on my cylinder heads, camshaft and intake. At this point, all I understand for the cylinder heads and the intake is to focus on the CFM flow. The cylinder heads have a certain amount of CFM flow at different increments of valve lift, and the intakes are designed to flow at a constant amount of CFM. However, how can I choose a camshaft? I would prefer something off the shelf, simply because the price is right. I know a custom camshaft may yield a significant amount of horsepower, but my project may change later - if I become more power hungry.

I used Comp Cams, but I would like to understand how to effectively choose a camshaft - at least a little understanding of lift and duration. In lamen's terms, a simple explanation of why someone would say purchase Steeda 18 rather than FRPP X303. How do these camshaft specs equate to understanding the best combination for a certain set of cylinder heads and intake?

I am debating whether to purchase a Trick Flow kit or seek a cheaper solution using FRPP GT40X (since they are priced EXTREMELY cheap at Jegs).

Once you have the right cam bolt pattern and journal design, there are just a few specifications that differentiate cams. Duration, Lift, Lobe Separation, ABDC, ATCD, BTCD, BBDC.

Commonly only duration and lift are mentioned and are usually the only thing you need to concern yourself with.

From my practical experience of designing and building cams for most of the companies that sell aftermarket cams, there is virtually no difference other than the markings on the cam and the box they pack it in. Many cams come from the SAME aftermarket manufacturing company. (at least they used to 6 years ago)

Picking the right cam is a function of use, vehicle weight, gearing, cubic inches, static compression ratio, power adder, heads, intake, carb. All have to play together.

Even with my experience with cams, I worked with a custom cam designer to find the right profile for my combination. I used Predator Cams out of PA, I liked their prices and experience. They were straight shooters that made sure everything I put together will work in harmony.
 

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Discussion Starter #3
How much did they charge you for your custom camshaft?

I would like to avoid purchasing the Trick Flow System, and instead, use the FRPP GT40X mated to a DSS 306 short block. But if I do that, I would squeeze some more cash into the camshaft to make up for the loss power. I want to say I can at least make 300RWHP. Hopefully... :happydance:
 

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Camshaft selection is a very complex interaction with everything that has an effect on the airflow. The camshaft will also greatly affect life of valve train components. There is no easy way to predict what you need except through experience, that's why a call to the cam manufacturer or an experienced engine builder would be best.

If you have an engine that is "on the pipe" (I had a 330 cu that was "on the pipe") you want huge valve open times with overlap so the exhaust sucks air into the cylinder and then when the back-pulse comes along it rams the unburned air-fuel back into the cylinder. My cam in that engine had the valves open most of the revolution, and the lift was way over .8 inches. The lift had to be that high so the cam could have a steep ramp without overshooting and losing cam to lifter contact.

Naturally aspirated in a 3000 pound car, that engine ran 8's in 1/4 mile without power adders of any kind.

My present car has a blower, so I want very little overlap and a wide centerline. I don't want to blow air pressure out the exhaust.

I'm a firm believer in BIG cams with big lift and duration if it is a naturally aspirated racing motor. Even for the street with N/A I use big off-the-shelf mechanical rollers, the biggest street grinds comp cams offers. (We didn't see any improvement with a few custom grinds, so I pretty much stuck to off the shelf cams.)

Call the cam manufacturer. Tell them what you have.

Tom
 

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How much did they charge you for your custom camshaft?

I would like to avoid purchasing the Trick Flow System, and instead, use the FRPP GT40X mated to a DSS 306 short block. But if I do that, I would squeeze some more cash into the camshaft to make up for the loss power. I want to say I can at least make 300RWHP. Hopefully... :happydance:

I paid $195 for a grind. I have Roush cam needle bearings in my block which makes buying an off the shelf a little more tricky.

Scooter at Comp will help you if you with your particulars.
 

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Understanding all aspects of a camshaft and all the particulars are like trying to take an entire Physics course... it's too much to type here and a lot of the language wouldn't even be understood unless you have lots of experience in engine design. The best route would be to let the experts decide for you.
 

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Discussion Starter #8 (Edited by Moderator)
The Comp Cams program was very useful and narrowed my choice to several camshafts that suit my build. I am most likely going to look into the XE270HR. However, now that I want to purchase a set of AFR 165cc, the choice with springs seem to become more problematic.

Also, thank you RLG and old man for the input. The articles explained several factors as well as simplified the terms associated with camshafts.
 

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Matching all the parts is worth the money to do it right the first time.
 
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