Blower cam for my 427
05-25-2008, 06:30 PM
#12
The cam I have in my TrailBlazer SS and the 427 SSR is a great grind. It is sold through Leading Edge Performance by a friend of mine in Vegas for my customers. It is a 224/230 .612/.612 with a 116 LSA and -5 degrees of overlap.
05-25-2008, 10:55 PM
#14
This cam is installed straight up so no need to degree it in. I dont remember if it has any advance built in and I dont have the cam card here. The specs are for 1.7 ratio rockers, I dont like the extra noise from the higher ratio rockers. If you are going to have a custom cam made up then put the lift and duration in the cam and use the 1.7 ratio rockers (just my opinion).
05-27-2008, 12:21 AM
#15
Ok, to help you out. The exhaust duration will play a big role in your power band and how you make TQ. You want anything under 6K rpms, like a truck should, then shorten it up. Yes I know you have a blower and the Forum rules say you always need more exhaust duration. Thats crap. I run single pattern cams all the time with blower setups, and sometimes less duration than intake as well. Its just about where you want it. Thats all. Dont worry about getting it out unless you are spinning it high.
Assuming all centerlines are equal, a longer duration exhaust will open the exhaust valve sooner than a smaller duration would. What that means is you have less work on the piston to use after combustion happens. So if you want a good working TQ cam, then hold the charge longer. Hence the shorter exhaust duration. The only thing you need to figure out is where your power band is needed and what you are willing to give up. Not much is needed with these motors. The heads are great. So when you hold the charge longer, you give up top end. But who cares on a truck.
This should get you started in your thinking process. Its good to think about the whys and whats, and not just the numbers.
R
Assuming all centerlines are equal, a longer duration exhaust will open the exhaust valve sooner than a smaller duration would. What that means is you have less work on the piston to use after combustion happens. So if you want a good working TQ cam, then hold the charge longer. Hence the shorter exhaust duration. The only thing you need to figure out is where your power band is needed and what you are willing to give up. Not much is needed with these motors. The heads are great. So when you hold the charge longer, you give up top end. But who cares on a truck.
This should get you started in your thinking process. Its good to think about the whys and whats, and not just the numbers.
R
05-27-2008, 09:04 AM
#17
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Running LS7 heads changes alot of things.You can't run the same Cam that people with stock style heads are or you will be very unhappy.
Last edited by trever1t; 05-27-2008 at 10:02 PM.
05-27-2008, 09:09 AM
#18
Blower cams like the Lobe Separation angles between 114-118 depending on the RPM range you are looking for. The negative overlap will retain boost where as a positive overlap will bleed off boost. The duration and lift should be determined by the flow characteristics of the heads. Extra exhaust duration can compensate for less exhaust flow. We used this cam for the L92 heads but it works great with the cathedral port heads also. The L92 heads I am using flow just over 350 on the intake and 250 on the exhaust at .600 lift.
