Time for a cam!
Hi-Rev Motorsports
Joined: Aug 2009
Posts: 4,898
Likes: 65
From: Northern Indiana
you have to be very careful picking a cam for a truck....or any auto for that matter.
When you go bigger you tend to make more power and torque but, the side effect is that you more the place where it makes power and torque higher in the RPM range...
In a 4 wheel drive truck this ican be a very bad thing....
the Torque and Power curves are in a "Band" or "Range" if you will. Those ranges are lifted thru the use of lifting the other timings
Take for instance your stock cam... it may make power from 1,200-4,000rpm but now you want more power so you order a cam with more Duration and Lift to make the power numbers higher. If you gain 20% power you raise the curve 20% mostly as well... the ONLY way to make more power in a typical engine is to raise the RPM range where Peak occurs...
so now you have a cam thats range could be 2,200-4,200.... is this bad? yes and no
if you have changed nothing but the cam yes... as the engine wont make any power under the range so the truck becomes an instant turd and take off is way worse than that of the stock cam....
A stock torque converter is meant to stall in the cams range of power production to help get the vehicle moving... the heavier the vehicle is the more it becomes dependant on the converter and rear end gears.... so if you change the cam a fair amount you will need more converter and rear end gears especially with larger tires.
a Shorter duration cam (stock or close) makes all the world in take off... it will mean your buddies beating you off the line and you having a very hard time catching them because you struggle getting the engine into the power range.
as I have ALWAYS stated I suggest going NO MORE than a 214° actual duration and even then its iffy and I would Advance the cam myself an honest 8° or more
When you go bigger you tend to make more power and torque but, the side effect is that you more the place where it makes power and torque higher in the RPM range...
In a 4 wheel drive truck this ican be a very bad thing....
the Torque and Power curves are in a "Band" or "Range" if you will. Those ranges are lifted thru the use of lifting the other timings
Take for instance your stock cam... it may make power from 1,200-4,000rpm but now you want more power so you order a cam with more Duration and Lift to make the power numbers higher. If you gain 20% power you raise the curve 20% mostly as well... the ONLY way to make more power in a typical engine is to raise the RPM range where Peak occurs...
so now you have a cam thats range could be 2,200-4,200.... is this bad? yes and no
if you have changed nothing but the cam yes... as the engine wont make any power under the range so the truck becomes an instant turd and take off is way worse than that of the stock cam....
A stock torque converter is meant to stall in the cams range of power production to help get the vehicle moving... the heavier the vehicle is the more it becomes dependant on the converter and rear end gears.... so if you change the cam a fair amount you will need more converter and rear end gears especially with larger tires.
a Shorter duration cam (stock or close) makes all the world in take off... it will mean your buddies beating you off the line and you having a very hard time catching them because you struggle getting the engine into the power range.
as I have ALWAYS stated I suggest going NO MORE than a 214° actual duration and even then its iffy and I would Advance the cam myself an honest 8° or more
Martin
Joined: Jan 2011
Posts: 3,036
Likes: 260
From: Lehi, Utah
I am also working on a cam selection. I spoke with a cam shop in Tacoma. They said to pull the stock cam out send it to them they would spec it and regrind it. My question going this method, is what can be changed and what can't be changed? Where I'm looking to just use the truck to tow excetera, he felt that would be my best method.
Hi-Rev Motorsports
Joined: Aug 2009
Posts: 4,898
Likes: 65
From: Northern Indiana
that would be a question better asked them...
Lift can be adjusted by taking off the base circle and Duration a slight amount as well as the LSA....
if you take material off the bottom you gain a ton on the top and you can reshape the lobe where you want it inside those lines...
Lift can be adjusted by taking off the base circle and Duration a slight amount as well as the LSA....
if you take material off the bottom you gain a ton on the top and you can reshape the lobe where you want it inside those lines...
Thread Starter
Member
Joined: Jun 2011
Posts: 81
Likes: 1
From: Backwoods Of Pennsylvania
I am also working on a cam selection. I spoke with a cam shop in Tacoma. They said to pull the stock cam out send it to them they would spec it and regrind it. My question going this method, is what can be changed and what can't be changed? Where I'm looking to just use the truck to tow excetera, he felt that would be my best method.
