Cam's control errors, power differences and limiters/lockers need.

[lito]

Ok, I've seen this from time to time and this is by a lot the worst case so far, answering some questions to Fast_3V the other day, decided to make a thread with some data of this case (which as said, is the worst of all but there are more).

Car is a 07GT with 2xk kms, auto, stock everything except:

- JLT3
- 127400s with 113 springs, comp retainers and livernois limiters
- Pypes headers with O/R X.
- 4:30

Car make no weird noises, no weird behavior, no codes (except cats), running on a tune I emailed in the meantime. Install was made by a local "Ford tech" but as said, nothing weird.

First runs, one short and as AFR was on the safe side one up to the 6.5K range and I find there is no control on the cams, once you gave it gas, cams hung on the limiters. Pic shows TP_RELATIVE for throttle and ACT CAMS ANGLE for cam retard, in any condition they were hanging on/close to the 20 degree max allowed by the limiters.

Decide to run basically the same tune but with the cams all advanced and this is what we got:

Here are the dyno results of both runs:

First run (20 retard) is the green one, second is the blue (0 degree)

The retarded run is slightly richer as expected but peak gains are about 10hps from retarded run but big differences are on the lower area torque with up to 50lbs loses.

I have seen this quite some times, where the VCT looses control, once you command any kind of retard they go all the way or most of it, depending of maybe oil temp conditions or some other stuff I have not found out yet.

Our temporary solution is to take the VCT as it was RPM switched, like a two position thing and set an RPM before it runs out of steam and then retard to flatten and extend the power curve.

The result:

An the yellow line on the graph (which involves more timing and less fuel appart from other stuff, more than the values itself, the shape of the curve is what is important)

So, if you use cams with some lift and duration that require stronget springs, get your limiters, in this case in particular, if they weren't there, PTV contact would have occurred.

Now, what is better? depends on the combo you are running, but run something, lockers are not that bad powerwise if you set your cams correctly, running shorter retard limiters is an option if you may suffer from zero VCT control as you know that your retard will always be the limiters set degrees.

 

[BruceH]

I have some examples of the same cams. You can see how much they vary on rebound. Livernois limiters, 26113 springs, 5w-20 oil, stock oil pump. The scale is in cam degrees. The components besides the cams, springs, and retainers were all original equipment.

Commanded 0 degrees:



Commanded 5 degrees:



Commanded 10 degrees:



The current setup is locked out with a 108 icl. It felt good na and even better with boost. I think that with a pd blower the driver will never notice a loss if the cams are locked out at the ideal icl for higher rpms.

 

[eighty6gt]

The current setup is locked out with a 108 icl. It felt good na and even better with boost. I think that with a pd blower the driver will never notice a loss if the cams are locked out at the ideal icl for higher rpms.

For sure. I fail to recall any elegant lockout solutions, time to start wading around... hehe. I think Lito is on to something where I use the 11 cc dish 2v pistons, then use limiters. Would prevent PTV issues and if he keeps an eye on what's happening with the stock valvetrain I'll still get some benefit out of the stock VCT system.


Edit: hehehe "Cute donkey." I called my old mustang the "Old Grey Mare."

 

[lito]

For sure. I fail to recall any elegant lockout solutions, time to start wading around... hehe. I think Lito is on to something where I use the 11 cc dish 2v pistons, then use limiters. Would prevent PTV issues and if he keeps an eye on what's happening with the stock valvetrain I'll still get some benefit out of the stock VCT system.


Edit: hehehe "Cute donkey." I called my old mustang the "Old Grey Mare."

The worse thing is that was actually the nickname of the car owner, not the car itself, lol.

Get the livernois, lockers or 10/20 limiters, simple and effective. Limiters will always give a slighter wide powerband but is not the end of the world difference, bad is if they stay retard as this case, car was terribly slow down low. Depending on boost and even keeping stock cam, an spring upgrade desirable.