What is your favorite blower cam?

 

For what size motor and what blower? What's the cam profile?

Mark

 

Here's my setup, I have to change cams bc I can't make over 4#'s boost w/ this one. What h/c pack are you all running?

http://www.cardomain.com/id/cmkworm

 

For a 346cid LS1 the FM7 is doing really good.

 

Ya, that 112LSA is hurting u.
Mine is in sig. You can go a bit larger on the split duration.

 

Gotta love the '02+ Z06 cam for all-around street manors on FI.

 

I am running a 220/224 .581/.581 115+2 using Comp XE-R lobes and am quite happy with it.

 

225/225 .581/.581 113 LSA with AFR 225's not together yet but i think it work pretty nicely.

 

vortech c5 i sent you a pm

 

230/236//114//+2 is the biggest I would with a stock bottom end. I made 738rwhp with one.

 

Well you can't blame the cam for having overlap and bleeding boost because your cam actually has -2* of underlap. Yes, 112lsa cams in the smaller durations do underlap.

So, why only 4 PSI?

 

Shop said cam was letting all boost out exhaust.

 

No overlap with a .222/.222 (Dur.) .566/.566(Lift) 112 (LSA) ???
CMK, I'd call CompCams to confirm.

 

NO WAY! The numbers don't add up. You have no valve overlap so that can't possibly be the issue. Call your cam manufacturer and verify this information then when the manufacturer confirms this info call your tuner or shop and talk to them about it.

You should be able to run your P1SC to the 5-7 PSI range with no problems. Now, with the cam having a smaller duration and not being a traditional split to allow for more exhaust duration than intake that could play some role in it, but I doubt it would keep you from making the 5-7 PSI your procharger is capable of.

Worse case senario change your cam to something with a 114LSA minimal and in the proper durations to give you the power curve needed for your driving habits.

 

Ya know, boost is relative to backpressure. Just because you are only making 4#'s of boost doesnt mean you arent making the horsepower. Have the car dyno tuned and you might be pleasantly suprised...


BTW, you have to take into account the fact that you have a FMIC witch will drop boost #'s 1-2 pounds in a normal situation due to the increased density on the output side...

 

LPE GT2-3 207/220 dur .573/.580 lift on a 117.5 lob sep

 

Slight correction, the LPE GT2-3 cam has a 118.5 LSA.

Mark

 

Sorry Mark, I gave the old specs. New ones are slightly different. Duration is the same, lift is now .571 / .578 on a 118.5 lob sep. They have a new cam out called the GT7. Specs are 208/230 .554/.546 on a 121 cl.

 

Sorry, but I don't believe this is correct. 112 lsa -2 (if that is what it really is; I doubt it) will have more overlap than a 114 lsa +4 regardless of the duration numbers. This will bleed off some boost, especially at higher rpms, and will also have lower vacuum at idle. The -2 and +4 only change where the valve events happen in relation to the crankshaft, or in other words, where the piston is in its stroke.
Example: I have a 216 intake duration cam on a 114. If you decrease the lsa to 112 you will bring the lobes closer together and increase the overlap, and if you increase the duration to 222, you will increase the overlap slightly more because you increase the lobe breadth by 3* of cam duration on each side of the lobe centerline. So, for overlap to be decreased by simply reducing the duration, you would have to reduce it a lot to make any significant difference.


Sort of right, sort of not.

Boost is relative to backpressure, but that is measured in the intake manifold. A high flow fmic will relieve backpressure at the compressor, but will increase pressure in the intake because it will allow more airflow. When you decrease airflow restriction before the intake, you increase airflow at the intake, increasing boost. When you decrease restriction after the manifold (better heads, headers, exhaust), you increase airflow beyond the manifold, decreasing boost.

So, having said all that, CMKworm, I would ask what are your pulley sizes, or what is it pulleyed to make on a stock motor? I am going to guess and base my next comments on a 7 psi P1SC tuner kit for a stock motor. If the track times in the link are accurate, I think that you are probably bleeding a little boost and maybe seeing a little belt slippage. However, 11.65@120 is very good for this setup. I would expect you would be seeing less boost due to the freeflowing heads and exhaust you have. Some dyno pulls would tell if you have any belt slippage because at upper rpms where you would expect to be making more boost, it will flatten out and, in all likelyhood, you will be able to smell the rubber getting hot.

As for what cam I like.....it's a secret. J/k I never recommend a specific cam because it is best to match the cam to the flow numbers/characteristics of the heads. However, if you are going to change it, I would close up the lsa to a 114 or 115 and go with a split duration (for superchargers I would start with about 8* more exhaust duration. The duration numbers affect where in the rpm range you begin and end making power. If you go with big duration numbers you push the power band higher in the rpm range, smaller numbers, lower in the band. Lift numbers should match the head flow numbers closely. If your head flow numbers flatten out around .500-.550, you don't want a cam with .595+ lift; that is overcammed. If your heads flow 300+ at .600 and don't show any flattening compared to .550 and .500, and your lift is .575, you are undercammed (that is, if you are after max effort). Whether a split lift is called for is debatable on supercharged motor; it, again, depends on the headflow characteristics. In my opinion, additional exhaust lift over intake lift will not hurt (especially if the exhaust valve is small, like the stock 1.55, or the 1.57) unless it is excessive. If you know who ported the heads, I would contact them, tell them what you want to do with the car, tell them all the stuff you already have, and ask them to recommend a cam. After all, who better than the person who is intimately familiar with their own product.

Sorry so long, but when you ask for a good blower cam, it is good to know what the numbers mean, how they relate to each other, and whether they will enhance or work well with what you already have. When someone recommends a particular grind and you don't know how this will play with your other components, you should ask them why they are big on that cam and why they think it will enhance your setup. If they can't say, they shouldn't have said. Just my opinion, and no flames intended to any comments made above.

 

CMK, how much Overlap did Comp say you had?