really depends on the kind of boost you are talking about...
a cam that works well in a supercharged setup may not work so well in a turbo setup.
the same goes when comparing an n/a cam to either forms of boost.
so cam choice when boosted can be important

here is some info i found on cams with boost..
this is more in regards to turbo, but im assuming it would still apply in supercharged applications..??

this is alot of reading, but taken from a mix of sites:
The following is meant to be a GUIDELINE for choosing a good cam for a turbocharged vehicle. Sources are cited.

First Step is to remember what Corky Bell, the author of Maximum Boost, has to say about cams and forced induction:

Camshafts
Make no mistake in the fact that the turbo performance cams are very different from atmospheric performance cams. The characteristics of long duration and high overlap for atmo cams are unwelcome in the turbo system. The street turbo, which is generally small, operates on exhaust manifold pressure somewhat higher than intake boost pressure. This situation, when presented with long-duration, high-overlap cams, creates a huge amount of reversion. Thus the "turbo cam" tends to become a low duration, very limited overlap camshaft..

RULE: It is hard to find a turbo cam that works better than the stock item.

Also consider the legendary "inertia files" which also teach us the science behind cams and why it is so hard to improve the stock cam in a forced induction application:

So remember, overlap= bad. Although it is hard to find a better cam than stock, we can still try...

http://www.forcedinductions.com/help.htm


How to select a turbo cam

Duration:

Duration is critical to a turbo setup since its probably the single most important event of a turbo motor (i.e. time valve sits open and closed). Since the air is being forced instead of drawn into and out of the combustion chamber, duration will be your largest variable on how that incoming/outgoing air is managed.

Duration when using a manifold or log design on most turbo cams is usually about 6 degrees more intake duration than exhaust duration (226/220, 240/234). This is mainly because a manifold/log design will typically see higher then a 2:1 pressure ratio in the exhaust ( as high as 4:1 with some logs). By using a reverse split duration this will somewhat help prevent from getting exhaust gas reversion.

Duration when using an efficient header setup with most turbo cams will usually be (230/230, 224/224) or better known as a dual pattern cam. The thinking is with the exhaust backpressure being only 2:1 you can leave the exhaust valve open a little longer then if the exhaust backpressure was 3:1 or higher. Also some of the new turbo designs produce a much lower backpressure with the advent of better flowing turbine wheels and housings which further decrease the total amount of backpressure created by the system.

Overlap:
Overlap definition, is the time period when both the exhaust valve and the intake valve are open at the same time. The exhaust valve needs to stay open after the piston passes TDC in order to use the vacuum created of the exiting exhaust gases to maximize the amount of exhaust gas drawn out of the cylinder. The intake valve opens before TDC in order to use the vacuum created by the exiting exhaust gases to start drawing the intake charge into the cylinder.

This sequence of events above are controlled by the duration and LS (Lobe separation) of the cam. On a typical N/A motor this is essential since you have no pressure being developed on the intake side to push the charge into the combustion chamber. The problem with this event is a turbocharged motor will create a larger amount of backpressure on the exhaust side. Due to this event the above definition will not apply. Reason being is, when the intake valve opens at BTDC, the burned gasses in the chamber will exit out the intake since the pressure is lower than the exhaust. Since this is true you would not want to open the intake valve until the piston has started going down, ATDC. This will lower the combustion chamber pressure till it's below the intake manifold pressure.

To calculate the overlap of your cam simply follow these steps below:
**Example turbo cam:**

Duration @ .006 218/212
Lift .544/.544 lift
Lobe Separation (LS) 114

Add the intake and exhaust durations
Divide the results by 4
Subtract the LSA
Multiply the results by 2

Overlap is -13 Degrees of overlap


**Example N/A cam :**

Duration 236/242
Lift .568/.576
Lobe Separation (LS) 112

Add the intake and exhaust durations
Divide the results by 4
Subtract the LSA
Multiply the results by 2
Overlap is 15 degrees of overlap

Above was the process on how to calculate your cams overlap. As you can see, the overlap in the 2 cams differ greatly. Running the N/A cam example on a manifold setup would be a horribly in-efficient setup and the engine would be operating well below its potential output. While running the example turbo cam would work well even with the most in-efficient of the header systems out there. Typically a overlap spread of -8 degrees to +2 is a safe bet. Of course this will differ with whatever combination header, turbo and exhaust is used, so those #'s could be higher or lower.

Lift:
How much lift should I get in my cam? Well that will depend on your heads' flow characteristics. To choose the correct turbo camshaft, you really need to know how your cylinder heads flow. Reason is if your cylinder head flows X amount of air at X amount of lift, choosing a cam that has a lift much greater then that will gain you nothing except extra heat and premature wear of the valve spring. Airflow through a head reaches a peak as the valve is opened, then starts to drop off as the valve is lifted beyond that peak. Most of this of this will hold true to definition, but with a forced induction motor, valve lift is not as critical since the incoming air is pressurized.

A good rule of thumb is to select a cam that will lift the valve 20-25% past its peak flow point.

So be the definition above if your head flows best at 0.500" of lift, use a cam that will lift the valve between 0.600" and 0.625". The reasoning behind this is, if you lift the valve only to its peak flow point, then the valve only flows best when it's wide open. The cycle is brief and would only happen once per stroke. So to benefit from you peak flow the most, you want to lift the valve past its peak. That way the valve will pass its peak flow twice in the cycle. The result is more flow during the opening and closing event of the valve. You do not want to raise the valve much past the peak flow though, or you lose total flow by going too high.
Calculating the best lift:

0.500 X 1.20 = 0.600
0.500 X 1.25 = .0625

Conclusion:
There are way too many factors to just say XX cam will make XX power with your combo. Things like "114LS is best, or 117LS, or ..etc", are just blanket statements. Backpressure, RPM range, boost level, target horsepower, A/R of turbo, turbo frame (T3, T4, T6/Thumper), head flow, cubic inches, and even location of turbo...etc. All of these factors are extremely important in determining the cam that best suits your needs. There is no rule of thumb with a turbo cam. There are too many variables and the only way to get the right cam is to take all of those your parameters into consideration, and only then can a proper cam be selected. All of the points of reference above are just to get you on your way to building the best and most powerful turbo system for you. Study your design and ask questions along the way and you will be smiling the next time your opponent lines up next to you.


More Cam info from: Piper Cams - Technical terminology

"Cam Timing: The position of the camshaft relative to the crankshaft. This is expressed as the number of degrees that full lift occurs after top dead centre (tdc) in the case of the inlet, and before tdc for the exhaust. This figure is included in the catalogue pages, but to calculate this, take the duration figure and divide by 2. EXAMPLE: With an inlet cam of 23/76, the duration is the addition of these two numbers, plus 180, equals 270. Then divide by 2 resulting in 135. Deduct the number of degrees before tdc that the valve started to open, ie 23 degrees - the result 112. The valve is correctly timed with full lift 112 degrees after tdc.

Valve Timing: The opening and closing position of inlet and exhaust valves relative to the crankshaft as figures before and after TDC and BDC

Lobe Angle: The angle between the inlet and exhaust lobe, measure in degrees.

Ramp: The ramp is the part of the profile that takes up the valve clearance and slack in the valve train gradually, before the valve is actually lifted from the seat. It also rests the valve gently back to the seat after the closing flank. Mechanical profiles use a much larger ramp than hydraulic ones, as the hydraulic cam follower should be in contact with the lobe at all times. The height of the ramp dictates what measurement the valve clearances should be set to.

Flank: This is the part of the profile between the ramp and nose. It is the most important part of the whole design. The flank controls the velocity and acceleration of the valve train. The acceleration / deceleration rate must be within the working limits of the valve spring, too much and valve float with occur. Generally high acceleration & velocity figures are beneficial to engine performance.

Nose radius: The larger the nose radius the better. Our profiles are designed to utilise the biggest nose radius possible to keep the stresses to a minimum.




Dwell: As the valve reaches full lift it will stop moving for a few degrees before starting to drop back towards the seat, this period is known as the dwell. When checking the cam timing using the full lift figure method the mid-point of the dwell should be taken as exact full lift.
Rocker Ratio:The ratio between valve motion vs cam follower motion. Push rod engines typically use a ratio of between 1.1:1 & 2.0:1. Over head cam, direct operating engines obviously have no rocker ratio as the cam follower motion is exactly the same as the valve motion.

Overall height: The measurement from the nose of the lobe to the bottom of the base circle, in a straight line through the centre of the lobe.

Base circle diameter: The measurement across the lobe, calculated by measuring the overall height and subtracting the cam lift."
- Piper Cams frames page

great post Troy. Very interesting info. I'd still like clarification of supercharger cams if there is any co-relation of those cams with NA/turbo grinds.

troy, supercharger cams are different to turbo cams.
its a different form of boost, ie. less back pressure and what not.
im not sure how it affects the cam choice though.

Troy,

Thats not a bad read... Helps with the understanding of how cams work and why you those number ranges you look for with a turbo cam...



Clampy,

You installed the 1636 yourself? Did you use a dial indicator and if so what did you dial it in to? 54thou at the lobe, or 54 thou at the valve @TDC

Only reason I ask is Wade's spec sheet says 54thou at the Valve, when you ask Wade they say in emails 54thou at the lobe... Now I'm confused...

If you get it wrong will it break anything or just run like a b**ch?

Cheers,
Tim

ive got the 1673 in my car and im using the standard cam gear...
from what i have read most wade cams are ground to work with standard cam timing but can be tweaked slightly

im not convinced..lol
what do you mean less back pressure??
the only difference i see is a turbo relies on exhaust pressure/volume to drive it and supercharging is driven by a belt...
otherwise they are both getting s**t loads of air being forced into them and both need free flowing exhaust to get rid of the gasses..

A.Graham Bell author of Forced Induction Performance Tuning and Four Stroke Performance Tuning has this to say.

pg 239 Blower engines have a problem which is the exact reverse of turbo engines. Pressure in the inlet port is basically always going to be higher than in the exhaust port, with the consequence that during the overlap period...fresh air/fuel will flow right out past the exhaust valve.

Lobe Separation Angle should be 112-115deg. Cam advance 4-5deg.

Blower Cam Guide - Street
1.7:1 Rocker Ratio (EB-EF are 2:1 & EL/AU are 1.8:1)
Inlet lobe duration 198-214deg @ 0.050"
lift 0.450 - 0.470"

Which going on the progression between the rocker ratios 1:1, 1.5:1 & 1.7:1 suggests for an AU you would need 196-212deg @ 0.050" & 0.460-0.480" lift.

Exhaust duration should be 5-15 deg longer than inlets for poor flow exhausts (American V8s).
2valve Hemi & 4V pent roof requir same inlet/exhaust duration. Race applications of these might need 4-5deg less & up to 5% less lift.

what i got is pretty close, 205 duration@050 & .512 lift the only thing i see as a possable negative is its a single patturn cam

From the sounds of those specs you have AU1645A cam then? IMO you have the right cam, and i've just put my own money on it too! I got one delivered this week.

I went for 112LSA to make it a bit more punchy. I too will be supercharging in the near future. I have a full 3" mandrel exhaust & 3" SS cat with my Pacie 4480 headers.

I think that the exhaust flow on these heads is probably good enough to be single pattern. I did look at making a split pattern by using the next cam up, the Wade 1521a which is 217deg duration @ 0.050 and use that lobe on the exhaust, but the lift was over what the stock springs can deliver.

The proof will be in the power/torque/economy combination.

I got a feeling the AU1645A cam (aka Troy's cam) will be too big for an auto without a stall. Can anyone confirm?