Stage I or Stage II Camshaft?

[F-15man]

Im rebuilding my quad to a 440, but I'm not sure if I should stay stock with the camshaft or go to a stage II. What are some ups and downs of this?

[Wheelie]

Depending on compression and true displacement, go w/a stg 2 at the very least, possibly even a stg3/stroker cam.

[F-15man]

would I still have the low end power as with a stage I?

[Wheelie]

No. The bigger bore and higher compression will help to compensate though. You'll probably end up with the same low end power a stock 400ex has, with more power in the mid and top.

[F-16Guy]

Shady-J!! :blah: :D

Do you know a fuel shop guy named Joe Michel? Old friend of mine.

A camshaft with longer duration (Hotcams stage 2/3, or one of the hotter Webcams grinds) will keep the valves open longer. If the duration is long enough, it will reduce the amount of time that the piston has to build cylinder pressure during the compression stroke. This is usually offset by increasing the compression ratio of the piston (why people buy a cam and piston together). If you run a high duration cam and a high CR piston together, you should notice very little loss of bottom end, and depending on the combination, probably an increase in bottom end along with the mid and top. When you increase the displacement to 440 CC's, you are effectively making a larger "pump", therefore, you should install a cam with more lift AND duration to allow that pump to operate at it's fullest capacity.

[F-16Guy]

Originally posted by Wheelie
No. The bigger bore and higher compression will help to compensate though. You'll probably end up with the same low end power a stock 400ex has, with more power in the mid and top.
Wrong. By increasing displacement and compression ratio, along with the Stage 1 cam, you'll have way more bottom end. You just won't get the mid and top end potential out of the engine because that cam has a lot of lift and a fairly short duration. With that big of a bore, you'll want to go with a longer duration cam, even if it has a little less lift.

[GPracer2500]

At 10:1 or 11:1 I'd probably choose a stage two. To back up what F-16 is saying, the added compression from the piston should more than make up for the shorter "effective" compression stroke of a longer duration cam. If you're planning on 12+:1 then I'd likely go for the stage three. Even at 11:1 w/ a 89mm piston I'd expect the stg 3 to be a fine performer--even down low.

Here's some numbers to provide reference for the differences between these cams:

Stock piston (9.1:1) cranking compression at 1000ft altitude--
Stock cam: 8.2:1
HC stg 1: 7.8:1
HC stg 2: 7.6:1
HC stg 3: 7.2:1

10.0:1 piston--
stock cam: 9.0:1
HC stg 1: 8.6:1
HC stg 2: 8.4:1
HC stg 3: 8.0:1

11.0:1 piston--
stock cam: 9.9:1
HC stg 1: 9.5:1
HC stg 2: 9.2:1
HC stg 3: 8.7:1

12.0:1 piston--
stock cam: 10.8:1
HC stg 1: 10.4:1
HC stg 2: 10.0:1
HC stg 3: 9.5:1

(Note: those numbers may not be quantitatively exact, but the relative differences between cams is accurate. The absolute numbers should be fairly accurate though. Using the same calculation method, my old 416 should have pumped 185psi and my guage showed 180psi cold--so I figure it's pretty darn close to correct.)

[Wheelie]

F-16Guy--

I was comparing low end power by using the stg2 as opposed to the stg 1.

Using the stg2 will offer less low end power than a stg1.

[F-15man]

ok. If i go a 11:1 piston ratio with a port and polished cylinder head, and a Stage II Cam, will I keep/ gain low end power? Also, What are the specs of a stage I, Stage II, and Stage III?