I'm Ryan Woody from Holley EFI and today we're going to go over some things in the Holley
EFI about how to get your car to spool faster in a drag race setting.
We'll probably talk about two or three different ways to do it and we'll just dive right in.
So the first way is using under our boost control ICF.
If you go down to the boost builder section we have some pre-canned parameters that you
can use to help with spooling.
They're fairly simple, there are more advanced and better ways to do it but this works for
some applications.
You have minimum TPS for activation, which is you just have to be over that TPS for it
to start doing anything and then a minimum and a maximum boost for it to activate and
that's just your window where it will take action and the two things you usually do are
fix timing, where you just manipulate the timing value or fix fuel value.
Sometimes you do both but mostly only on clutch cars.
Torque converter, automatic cars you'll use timing only usually and what that will look
like is you'll take some amount of timing that's way less than normal in a specific
window to get the engine to spool faster.
The magic is figuring out what numbers you need.
If you do it too early with this method it doesn't spool, the engine falls on its face
and you never go anywhere, it's worse than not using it at all.
If you are too late it doesn't help much, you don't pick up any time, I actually think
I have a good log of this so what I'm going to do is just set up a.
Actually go to file, open, and go to the default twin turbo injectors and see what I have there,
boost, target boost, this one will work.
Alright so we're going to de-activate AFR left and right, keep ignition timing, keep
our target boost, actual boost, there we go.
So if we go in here we can see that ignition timing is the gold line here, red line is
boost, red is RPM, so what we do is we let it get up nice and high and it gets up to
about ten pounds of boost before we turn on the boost builder, at that point it stops
the timing out, drops it to 15 degrees and holds it there to belt the rest of the boost
and you can see that when it actually happens it actually does bring the boost line more
vertical so it does help build boost faster and then once it gets to my target boost of
16 pounds, we turn the boost builder off and set the timing back in and that has the effect
of helping hold the boost steady.
As you add the timing you lose some exhaust heat and energy and when you step it back
down it adds heat and energy to the exhaust so what we are doing is balancing that timing
to keep the boost stable on the trans break so that's what this is right here is the timing
going in and out, in and out, in and out.
Then when you let go of the trans break timing goes back to normal, you launch at it looks
like he spun on this one.
The other method is more advanced.
The problem with this method is you have this step in timing and if you don't time it right
the engine RPM falls, so you can see that this one is already on the two-step so when
the timing steps out it doesn't affect the motor too bad but if I were to try to do it
back here, it's entirely possible the engine RPM would stop rising and just go flat.
If the boost doesn't keep rising at that point then you'll never get to the two-step and
you'll never launch, you won't go fast.
Right here where it wiggles, that's your two-step, that's my RPM, so there's a lot of cars, you'll
hear cars do it sometimes when they use this method, is they'll be coming up, coming up
in the RPM, and you'll hear them just stop for a second, and right there is usually where
they're stepping out the timing and in a data log you'll see that show up as kind of a flat
line and then it continues up.
So when you look at that one and you see your boost line here, when you see the boost just
starting to flatten out by the time I actually use it so the boost had, if you look at your
line, the boost had started to get flat just a little bit before so I actually I really
wanted to bring it back probably there or even back towards the beginning of the two-step
there so what I would have done in this case is, instead of using ten PSI on the tune,
so instead of turning it on at ten PSI, I would turn it on at seven PSI and see what
it did for the next time and then we would see if the boost line and the RPM line behave
so if RPM stayed up on the two-step we're good, if the boost line became more vertical,
because that's what we're looking for is a faster rise, then it's good and that was an
improvement.
If it comes and flat lines, either one the RPM or the boost, that was too early and I
need to do it a little later.
You know that's the easy method, that's what I tell people to do on cars that are just
getting started to try and if the car is becoming really sensitive then you go and build an
advanced table instead of doing it.
So what the advanced table would look like is instead of using the boost builder you
would go turn that off so you just come over here and disable that and that and then you've
got no boost builder, it's not doing anything, come over here and there are multiple ways
to do it, I prefer a 1D table, and just call it Spool timing is what I'll name it or Spool
Baby Spool and then timing offset is what you would use and then I use an X-axis of
boost then to turn it on I use a switched enable and I'll use the trans brake, launch
input, must be enabled and TPS is above 75 so you've pressed the trans break button,
you floored the throttle, we know that we want to build boost so we take this table
and we scale it for more than what your launch boost will be but not by a ton so since that
car, since this car is launching at 16 pounds I would actually put it at twenty and then
instead of having the timing step out I would probably by ten pounds call it nine pounds,
I would have that same amount of timing out which means that I had it going to 15 degrees,
the timing table shows we're roughly 34 so I would have to pull 19 degrees out of it
to acomplish the same thing.
So we would go to this nine pounds right here, I would pull minus 19 and I what I would do
is at 4 degrees, or four pounds of boost I would ramp it down and then we would hold
that 19 out all the way to our 16 pounds and then I would take at 16.1 and have it back
at zero and what that does is it gives us the same effect fo turning the boost builder
on and off at our set point so that steps the timing in and out and maintains boost,
but instead of stepping the timing out on the low side when we're building up, it ramps
it out gradually which has the effect of not shocking the motor and the boost curve so
you are more likely to continue that rise.
That's all there really is to boost builder, it's that simple.