Some of the real serious boost cams have intake valve events opening at 20-35 degrees PAST TDC! But those are for serious boost pressures!

well for the 2 cam i would maybe use the 108 for a restricted head and the 114 for the better flowing head.your thaughts?

Well selecting a cam should be more than looking at just one attribute. Just like a motor combo, you have to look at everything. I would never just pick a cam because of LSA or because of lift, etc.

As a general rule, a wider LSA will lessen the overlap, thus giving a smoother idle and broader powerband. But, with that said, a cam with an LSA of 110 could actually have less over lap than a cam with 112 LSA. You just have to look at the valve timing events.

for the theoretical engine we are working with your guess is as good or bad as mine.

even at 108 you would run that?^

Of the Two choices ,its the one that I think I theoretically would use. Id like to see a dyno comparison on both. IMO they would probably be to close to performance wise to one another to not really matter.

You posted a 20HP difference on one of your posts with a wider LSA, Im going to go back and read that again,

and the factors to say 20 hp was the later intake opening,longer ex duration.
later intake opening=better facuum betterVE% i think.
longer exh dur cooler intake charge=more hp

I checked your numbers and your first 254/110LSA cam has 39* overlap.
your newer cam 252/113LSA has 30* overlap.

The OP,s 240/108LSA cam has 24* overlap{approx} its probably 24.5 based on a MP 484 cam.

So thats less overlap then your motor with its 30* so 24* should be better yet.

So I think the overlap is acceptible of the 108 cam. The duration of 240* of the 108 vs the 232* .050 of the 114 cam will be the Trump card, for power on this "Theoretical Combo" IMHO between the two cams listed as options.

Just bench racing here, dont know for sure. But If i were building the OP,s combo in my garage, deciding on witch cam. Im picking the 108LSA 284/241

interesting now that all of the figures are out with the op cams.i need to ponder them more.
[I checked your numbers and your first 254/110LSA cam has 39* overlap.
your new cam 252/113LSA has 30* overlap.]


for my cams the 110 cam would not make boost past 8 psi even at 25% OD on the blower it quit at 5%OD.[10.90/? with the 113 cam the carbs held it back at 10 lbs at 10%OD[10.41/129
the cam in mine now is .646/.631 291/306 @ .020 260/269 @ .050
.050 in op 21 cl 59/exh op 69 cl 19 with 40* overlap at .050 without lash on a solid roller[.018 I/E] w 14lbs boost and more.

thanks for keeping the topic going.i dont know anything to keep it going from here. i guess i will pack some more boxes.i am moving.

i would only embarrass myself by letting you think i could explain it.
i thaught it may be a cracked port leaking for all i knew.a cam change made it better and i left it at that going from cam 1to cam 2.

from jegs helpfull tips on blower cams.
it is to help retain cylinder pressure with 112/114 lsa.

edit:i forgot to drag it back.
Supercharger Engine Camshafts
The choice of camshaft can make or break a blower motor. A legend in the industry, Lunati offers several camshafts specifically designed to work with Weiand blower kits. In addition, the following are a few basic guidelines for selecting the proper cam for your motor. Obviously, the amount of boost your supercharger produces is going to be a factor in choosing a camshaft. Weiand offers three different levels of superchargers, and each requires a different type of cam.

The "mildest" of Weiand's blowers are the Pro-Street superchargers, which are set to produce from 5 to 7 pounds of boost. The company recommends a hydraulic cam for these applications - where the engine will not be spun past 6,500 rpm and has several grinds available. All of these cams are ground on a 112 to 114° lobe center line, which helps maintain cylinder pressure to maximize horsepower at these lower boost levels. Keeping the cylinder pressure up also gives you excellent throttle response. The milder cams that Weiand offers are great for street performance enthusiasts who want to gain about 100 to 120 streetable horsepower. The company also offers slightly "bigger" cams for the next performance level up.

For 6-71 and 8-71 blowers, Weiand again recommends running a hydraulic cam, as long as you keep the boost level below 10 PSI. Weiand also offers cams for these type of applications. For your higher boost levels (which includes all 10-71, 12-71, and 14-71 applications) in gasoline burning engines, the company recommends running a flat tappet or roller cam with a 110° lobe center line. This cam design provides good overall power on pump gas and also aids in engine cooling. Plus, the 110° center line provides even sharper throttle response and helps lower initial cylinder pressure (you won't miss the cylinder pressure with these blowers, since they make plenty of boost).

440 and metalstorm, Could the boost increase that metalstorm saw an indication that the new cam wasn't flowing as much? The only way that I can see a cam making more boost on a blower motor is it is not using as much of the intake charge and it is backing up more pressure, seen as boost; as the supercharger will always be pushing out the same amount of air as long as the pulleys are not changed. Or another reason is if the motor is being wound out at a higher rpm to spin the rotors faster to make more boost, ie. flow more air. Am I thinking correctly? I've followed metalstorm and am building a blown 440 and am trying to pick a cam/lifter setup. I have a procharged SBC that I put a 110 LSA cam in and seem to have no issues, with the reason being that the overlap will keep the street driven exhaust valves cooler. Dan.

it could have even been valve spring psi that i could not gain psi.150# seat with cam 1#.the springs were spec from bds with that cam.
as for the restriction and gaining boost psi yes that would be a possibility in some casses like overlap and less going out the exhaust.an added note that my cranking psi went from 100# to 130 with the cam change #1 to #2.

Boost is just a measure of restriction in the system. I ran 452 heads on a 383 with a 224* flat tappet cam and 7.5:1 comp. It ran 12.64 at about 13 psi. Built a new much more free flowing combo same degree duration cam better heads and little higher compression. 9:1 and ran 12.36 at 4 psi. My point is who cares what boost is as it is a measure of restriction. What did the car dyno or run on the quarter with the same pullies and the different cams?

i cant recall the ET gain but it was a couple tenths.[.200 i think]