turbo cam ??'s
06-22-2005, 01:25 PM
#31
TECH Veteran
It's hard because you're talking to people with limited experience. You should fill out the request sheet at Cam Motion's web site and see what they have to say.
06-22-2005, 01:47 PM
#33
TECH Veteran
Originally Posted by 01Blackerado
thats funny cause thats how I came up with those numbers, only I put LS1 and ported flow numbers on the heads 
06-22-2005, 02:51 PM
#35
TECH Veteran
Originally Posted by 4.8T
so what is the web site
Click on 'Cam Requests'. You will have to register a user name and email address, then you can fill out a cam request form. It takes a couple of days to get it back.
Make sure you are completely accurate when filling out the form. For any questions or details put them in the comments section.
Let us know what they say when they get back to you.
06-23-2005, 05:37 PM
#40
what do you all think of this.
Here is the scoop on turbo cams: A lot of turbo systems create more backpressure than boost. As an example if you have a kit that makes say 8 psi of boost it might cause 12 to 15 psi of backpressure. This is very common in a lot of the 'street kits' on the market now. A good high-end race setup will make more boost than backpressure. If you have a cam that has any significant amount of overlap (the period when the intake and exhaust valves are both open) excessive backpressure will literally blow the exhaust right back into the intake because of the higher potential on the exhaust side vs. the intake side. Obviously you want to avoid this situation because it will totally murder your horsepower.
To give you a more direct answer. If the particular turbo kit you are using makes more boost than backpressure you can cam your engine just like a NA motor. If it doesn't ( which is highly probable with most street kits) you will need a cam with very low overlap. Reverse split cams are common with turbo's because it is an easy way to reduce overlap. I also think that some of it is a case of monkey see, monkey do. One person has sucess with a reverse split so everybody thinks that is the way to go. In my opinion having a lot of duration on the exhaust side isn't going to hurt (and in fact can only help) as long as we keep the overlap down. Think about this, if you have a lot of backpressure you will need more more time (duration) to get all of the the spent exhaust out of the motor. The Cheatr cam has a lot of exhaust duration but doesn't have a lot of overlap. That is why I think it will be ok for you. If you don't feel comfortable with it I can cut something for you with even less overlap but this will also reduce the exhaust duration. The Cheatr cam will seem a little big on a 4.8, it will work, but it may be a little on the big side depending on where you want the motor to make peak HP.
Here is the scoop on turbo cams: A lot of turbo systems create more backpressure than boost. As an example if you have a kit that makes say 8 psi of boost it might cause 12 to 15 psi of backpressure. This is very common in a lot of the 'street kits' on the market now. A good high-end race setup will make more boost than backpressure. If you have a cam that has any significant amount of overlap (the period when the intake and exhaust valves are both open) excessive backpressure will literally blow the exhaust right back into the intake because of the higher potential on the exhaust side vs. the intake side. Obviously you want to avoid this situation because it will totally murder your horsepower.
To give you a more direct answer. If the particular turbo kit you are using makes more boost than backpressure you can cam your engine just like a NA motor. If it doesn't ( which is highly probable with most street kits) you will need a cam with very low overlap. Reverse split cams are common with turbo's because it is an easy way to reduce overlap. I also think that some of it is a case of monkey see, monkey do. One person has sucess with a reverse split so everybody thinks that is the way to go. In my opinion having a lot of duration on the exhaust side isn't going to hurt (and in fact can only help) as long as we keep the overlap down. Think about this, if you have a lot of backpressure you will need more more time (duration) to get all of the the spent exhaust out of the motor. The Cheatr cam has a lot of exhaust duration but doesn't have a lot of overlap. That is why I think it will be ok for you. If you don't feel comfortable with it I can cut something for you with even less overlap but this will also reduce the exhaust duration. The Cheatr cam will seem a little big on a 4.8, it will work, but it may be a little on the big side depending on where you want the motor to make peak HP.