Hi, I'm Ryan Woody with Holley EFI and we're here today with another Holley EFI tech tip.
Today we're going to talk about wheelie control in a drag race application.
A lot of times wheelies are your biggest enemy because you are always trying to balance weight
and power, especially on a limited tire car and having a way to control that or to help
you avoid flipping the car over or having a catastrophic event happen is always a good
thing in this is just one quick way, I;m going to show you how to do it.
One of the key features of wheelie control is you have to have a ride height sensor and
it needs to work.
So the Racepak laser ride height sensor is a little sensor about this big that just has
a little optical eye on the bottom of it that points at the ground and it's using a laser
to tell how far away from the ground it is at all times.
So when you mount it you'll affect this reading at 3 1/2 at ride height here by where you
mount it, so that means that is physically mounted to the car and the eye of the sensor
is three and a half inches off the ground.
I'm rounding a little, it actually is 3.4.
So what you want to do is make sure that you have that set a low enough point that you
have enough range when the car comes up that it reads the full range of 14 inches and you
want to make sure that, because the car pivots on the rear tire, you want to make sure that
you don't have it too far forward or too far back that it takes either a really large change
in rotation to gain a half an inch or also in the front you may end up with too fast
of a change and 14 inches may be high enough that you don't even want to pull timing yet.
We have a drop down for it in the software so all you need to do while you are at power
and ground put a five-volt signal into the ECU and then select the right drop down here,
Racepak laser height sensor.
You go in, you set up an input, you title it whatever you want, call it ride height,
in this case, that's what I use, set it for 5 volt and then go to configure and we have
in the version 5 software, we added it as the laser height Racepak laser height sensor
and it's a direct drop down, it automatically scales it for you, gives you the right increment
in inches and then from there you go over to an advanced table, you can use a 1D and
you set up, enable the table, title it what you want, in this case, it's wheelie control,
use a timing offset, set your X axis to what you titled the input, in this case, it's ride
height and then you can set up your timing retard vs ride height.
So the important thing is when you mount the sensor to the front of the car or somewhere
on the car, you want to make sure that you have a decent range so we have a 14-inch range
on the ride height sensor, having it somewhere in the 2-6 or even 8 inch range from the ground
at ride height is important because if you have it sitting at 12 inches you only have
two inches of travel before the sensor is out of range.
So in this case, ride height is around 8 inches on the car, excuse me it's not around 8 inches,
ride height is somewhere around here at 2.8 and then what they'll do is they'll allow
the front end to come up to about 8 inches before they start removing timing.
After that point, they'll start ramping timing out fairly quickly to try to bring the nose
back down.
In practice, it looks something like this.
So we got a lot going on here.
Green line is TPS, so you can see right here, he came upon the TPS or the two-step, banged
it off the two-step, let go of the trans brake, up comes engine RPM, ride height shoots up,
ramps down a little here, comes back up, the yellow lines here are the wheelie control
activating, I'm actually going to change the color so we can see that, there we go.
So the yellow line is the wheelie control activating to try to keep the front end down
and you can see it actually tries to make the front end bobble right there and try to
hold it.
The shifter activates right here and it drops into the next gear and that sets the nose
down finally, but you can see it was starting to control to try to stop the rise of the
ride height.
That's how you set this up is you figure out what your actual ride height is here, 3.8
inches on this car, you need to figure out how high you are comfortable with the front
end coming up before you pull timing out, and then from there, we need to work on how
much timing you need to pull out to keep it down.
So there's no real set number to use for any of that, it kind of just comes down to what
you have for total timing in the motor and how sensative it is to the removal of timing.
Some engines one degree will make a big difference and set the nose down, other cars need something
like five or ten degrees.
I mean that's all there is to wheelie control, it's a lot of tuning, set up is very simple.
I'm Ryan Woody with Holley EFI and that's another tech tip.
If you have any suggestions for us go ahead and and put it in the comments or contact
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