Justin@VMP
January 28th, 2008, 11:57 AM
I will make some generalizations about aftermarket camshafts, after having worked on many mod motors with them.
Installation is key, two cams (or four on a 4V) all have to be aligned properly with each other, and with the crank. Many installers do not do this properly. This leads to poor idle quality and large bank to bank air/fuel ratio variances. In the extreme cases it results in engines that won't even run right.
I do not think there is a high degree of quality in some of the aftermarket grinds, I've seen cars with camshafts installed by reputable engine builders and mechanics that still had some funny quirks (poor power, poor idle, large bank to bank A/F variances).
Installation costs usually run upwards of $1000 due to all the labor involved, and the camshafts sets themselves are not cheap either. One can easily spend over $2000 having a shop do the whole project.
Everything comes at a price, higher lift and more duration in a camshaft also means that idle quality will decrease. In many cases, fuel economy, cold start quality, and driveability will also decrease.
In the GM LSx world, there are a variety of good cam grinds available that will make 30-50rwhp on a stock motor with a very acceptable idle and others that will make close to 100rwhp with a very lopey idle. Based on what I've seen so far though, we don't have that luxury in the Ford mod motor world. The GM world is a little different though, as they have more cubes to start with and only have one camshaft.
Here are a few case studies, the first dyno graph below is from two 05+ GT manuals. Both had LTs, CAI, CMCV deletes, no cats, VMP dynotune, and aftermarket mufflers.
The car in Run 5 had the more aggressive comp cams with upgraded valve springs. The car in Run 9 still had stock camshafts. I personally would not give up all the torque on the low end for 20 more RWHP above 5000 RPM. For a street car its not worth it, and for the money spent, its barely worth it for a track car.
http://www.vmptuning.com/dynographs/joevsjeffcams.jpg
Run 1 on the dynograph below is from a totally stock 05+ GT Manual. It made a healthy 259RWHP. With a tune we brought it up to 272RWHP. I was doing the dynoing and tuning for a companies aftermarket camshafts.
On the same day, the milder set of camshafts were installed. As you can see in Run 10, the car picked up a great amount of power and TQ at all rpm ranges, with the installation of the milder cams, a cold air intake, and a dynotune.
Now they went on to install a more agressive set of cams, they loped a lot more and the car sounded a lot meaner. But look at run 17, no matter what we did the car made less power. Bigger is not always better. I never found out what the problem was, the cams could have just been too "big", or not ground properly.
http://www.vmptuning.com/dynographs/3vcamtesting.jpg
At the end of the day, for the average Mustang driver, I would probably just install a roots-style mounted blower like a Whipple or KB and call it a day. The several thousand you would spend on cams+install would pay for 1/3-1/2 of a blower kit. A blower is pretty easy to install yourself, as its just a bolt on part.
If you are building an all out high compression NA motor then there is going to be a lot of merit to finding a good cam grinder and specing the right cam.
Now if you can do the cam install yourself and find a good cam vendor with real dynographs to back their stuff up, it may be worth it if you can do the project for a grand, IMO.
Installation is key, two cams (or four on a 4V) all have to be aligned properly with each other, and with the crank. Many installers do not do this properly. This leads to poor idle quality and large bank to bank air/fuel ratio variances. In the extreme cases it results in engines that won't even run right.
I do not think there is a high degree of quality in some of the aftermarket grinds, I've seen cars with camshafts installed by reputable engine builders and mechanics that still had some funny quirks (poor power, poor idle, large bank to bank A/F variances).
Installation costs usually run upwards of $1000 due to all the labor involved, and the camshafts sets themselves are not cheap either. One can easily spend over $2000 having a shop do the whole project.
Everything comes at a price, higher lift and more duration in a camshaft also means that idle quality will decrease. In many cases, fuel economy, cold start quality, and driveability will also decrease.
In the GM LSx world, there are a variety of good cam grinds available that will make 30-50rwhp on a stock motor with a very acceptable idle and others that will make close to 100rwhp with a very lopey idle. Based on what I've seen so far though, we don't have that luxury in the Ford mod motor world. The GM world is a little different though, as they have more cubes to start with and only have one camshaft.
Here are a few case studies, the first dyno graph below is from two 05+ GT manuals. Both had LTs, CAI, CMCV deletes, no cats, VMP dynotune, and aftermarket mufflers.
The car in Run 5 had the more aggressive comp cams with upgraded valve springs. The car in Run 9 still had stock camshafts. I personally would not give up all the torque on the low end for 20 more RWHP above 5000 RPM. For a street car its not worth it, and for the money spent, its barely worth it for a track car.
http://www.vmptuning.com/dynographs/joevsjeffcams.jpg
Run 1 on the dynograph below is from a totally stock 05+ GT Manual. It made a healthy 259RWHP. With a tune we brought it up to 272RWHP. I was doing the dynoing and tuning for a companies aftermarket camshafts.
On the same day, the milder set of camshafts were installed. As you can see in Run 10, the car picked up a great amount of power and TQ at all rpm ranges, with the installation of the milder cams, a cold air intake, and a dynotune.
Now they went on to install a more agressive set of cams, they loped a lot more and the car sounded a lot meaner. But look at run 17, no matter what we did the car made less power. Bigger is not always better. I never found out what the problem was, the cams could have just been too "big", or not ground properly.
http://www.vmptuning.com/dynographs/3vcamtesting.jpg
At the end of the day, for the average Mustang driver, I would probably just install a roots-style mounted blower like a Whipple or KB and call it a day. The several thousand you would spend on cams+install would pay for 1/3-1/2 of a blower kit. A blower is pretty easy to install yourself, as its just a bolt on part.
If you are building an all out high compression NA motor then there is going to be a lot of merit to finding a good cam grinder and specing the right cam.
Now if you can do the cam install yourself and find a good cam vendor with real dynographs to back their stuff up, it may be worth it if you can do the project for a grand, IMO.