Just got my cam in here's the specs...

.950 Base Circle
Intake : Duration 284 - Lift .545 ( with 1.5 rockers)
Exhaust : Duration 286 - Lift .554 (with 1.5 rockers)

Correct only @.050 tappet lift
Intake opens - 5.0BTDC
closes - 45.0ABDC
Exhaust opens - 56.0BBDC
closes - 0.0ATDC

Lobe Seperation - 114 degrees

Duration @ .050 Lobe Lift

Intake - 230 Degrees
Exhaust - 236 Degrees
Intake - .363
Exhaust - .369

Lobe Center 110 Degrees


Is it good?

 

I like it, but others will tell you it doesn't have enough exhaust duration.

 

Who made the cam?

My new blower cam is 236/243, I'm told that depending on your heads you don't always need 10-12* higher exhaust duration.

 

DEFINATELY not enough split between the intake and exhaust.

Rich

 

I've argued this (respectfully, Rich) very subject many times. . .

According to David Vizard's SBC Camshaft book, a low compression, supercharged engine retains cylinder pressure further down the power stroke than NA or NO2. I made an elaborate Excel Spreadsheet proving the same.

Think of it this way: Take a low compression combustion chamber to the extreme and make it as big as a room. Then fill it with 1000 psi gas. When the piston moves down on the power stroke, it doesn't drop the pressure in the room much because it didn't add much volume to the room. Now imagine a combustion chamber as big as a thimble and fill it with 1000 psi gas, making this a high compression NA motor. When the piston moves down, the pressure drops very quickly because you added alot of comparitive volume.

Once you get the concept, it is easy to see how it relates to a 104 cc combustion space (supercharged, low-compression) versus a 70 cc combustion space (high-compression).

Based on this, opening the exhaust valve early can be counterproductive to power on a supercharged engine since you are releasing the pressure that could otherwise be used to apply torque to the crank. Opening the exhaust valve later, thus using this pressure to make power, results in less exhaust duration. When the exhaust valve finally opens, there is more pressure in the cylinder to help propel exhaust gas out. Vizard does stress, however, that your exhaust port must flow well for this to work properly.

My AFR 210's flowed 280/218. Highlander's flowed around 282/220, but his exhaust numbers went to 274 cfm with a pipe. Think that's good enough for Vizard's theory to work?

Mike

 

We'll see if it works with my 276/210 flowing 193 cc heads.

 

It will work, just not well. Theory aside, it's not like there aren't a lot of SC LT1's out there. Reality trumps theory every time.

Anyway, the "split" is not intended to open the exhaust valve early, that why the LSA should also be relatively wide. It's to allow time for the large volume of exhaust to escape. Cams with equal exhaust and intake duration work great on NA cars with excellent exhaust ports and a very free flowing exhaust system. This is not typical of an LT1, so you will see a split even on a NA cam. It needs to be even bigger, 10-12 degrees or more (my current cam has a 15 degree split).

But you pays your money and you takes your choice, as in everything.

Rich

 

I would like to see a back-to-back dyno test. I know a guy who ran 147 mph with an 18 psi Procharged 355 with ported LT1 heads. This was with a 224/230 - 112 cam, which goes against most S/C cam logic.

Mike

 

Why dont we contact Bret Bauer and have him run a 230/236 and say a 224/236 both on 114lsa and see which one makes power? He can use his engine sim. software, unless he is too busy. His custom gring made 40hp more for my setup then going with a 214/224 cam I cant wait to see what kind of numbers it makes when I get this thing together!

 

Not to be a dick but put it together and get it running before you start spouting about the 40 hp more he got you from the "theoretical cam swap"

Unless it's a race car only, don't forget about drivability.

Some people are not fond of the CC305 (w/ 1.6 RR, it's 544 int / exh, 226 int 236 dur @ 0.050 and 114 LSA) but I'm running one and have had good luck with it, unless you don't consider 10.20's and 654 at the wheels good luck

Driveability is great and the car hauls the mail

Marc

 

I know the numbers are from the engine simulation. What it does is plot out what the hp/tq curves should look like, etc. The custom cam is significantly bigger, but will have very similar driveability do to LSA/overlap changes.

Not to be a dick back...but the cam your running isnt what you think it is The cc305 is a 220/230 duration cam and with 1.6R its .544/.544. You may want to look into this because you might not be running the cam you think you are

 

Whatever....

I don't have the cam card in front of me, I was just winging it.

I am running a CC305

 

Marc, that is certainly outstanding performance, but why did you decide to go with a smaller cam like that especially with a 383? Woulda figured something with CC306-like duration on a 114-116lsa for a more advanced setup such as yours. Not knocking the performance by any means, I hope my car is that fast when it's done, just looking for insight.

 

It's been proven many times that a properly set up blower car does not need a very "big" cam to make a lot of hp.

Rich

 

i've got a 224/236 114lsa for sale if your interested. nib