- This is kind of a weird test dudes.
- What do you mean?
- Well I'm trying to answer a question
that nobody has really asked.
How does temperature in the coolant
and the intake manifold affect performance
and what can you do about it?
- And we all know that's a way to cheat on the Dyno.
- It's not cheating, it's optimizing.
- Oh, okay, I'm sorry Steve,
I didn't mean to offend you there.
- That's right.
- So I think the first test we're going to do is
run the thing cold, coolant temperature
and then run it hot, coolant temperature
and then look at data.
We know it's going to lose power but I want to find out why.
- Well first of all, it's carbureted
so we're going to see some latent vaporization
and temperature drop in the intake manifold
unlike fuel injection where you're seeing
kind of this constant air temp throughout
the whole intake manifold.
- So you and I have bench raced this a lot
so I have to ask Dulcich, why do you think
an engine makes less power at heat?
- Air density. - Where?
- On the induction side of the intake valve.
- So you think at 190 degrees that air
in the intake manifold is going to be hotter
than it would be if the coolant temperature was 125 degrees?
- [Dulcich] I think so. - What do you think?
- So Holdener first said it and then you backed it up,
that the air temperature in the intake manifold's
not going to change with coolant temperature
and I've thought about that and thought about that
and thought about that, and didn't believe it
but I'm sort of coming around to it
but this is the test that's actually,
I think going to prove it.
And he's done it before so I say we just run it and--
- Yeah, it's going to be some pretty interesting stuff I think.
- Yeah, okay so our first run here
is going to be with our 598 at a cold coolant temperature
and we haven't altered the temperature
of the room or the intake manifold at all.
(engine running)
Okay, let's have a look at our power peaks
and then dive in to some of the temperature numbers.
Wow, we just made 790 pound feet of torque
and it made 854.8 horsepower and look at this thing.
It's 700 pound feet from the hit.
Okay, so that's our baseline power number
but let's have a look at what
the temperatures are telling us.
The air in the intake runner started at 76
which is really close to room temperature,
a little bit less, and then got cooler
and cooler and cooler as we went.
And it's not affected by windchill factor,
it's reading actual just temperature.
- Well there's more fuel with more air there
because at idle there's still a lot of air movement
and banging around with the air which causes some heat.
- And we have to give Troy credit, it's overlap.
- We're sitting here and Troy goes,
"What about the overlap at idle?"
- Yeah. - Cause there's all this--
And we both looked at Troy
and went-- - Duh!
Porkchop for the win.
- So the air during the overlap cycle
is coming back up and hitting this censor.
As engine speed increases, there's less reversion
and still the vaporization and cooling.
There's still a difference there and the air does heat up.
- So let me summarize.
We're looking at the temperatures in the room,
under the carburetor, and in the intake runner.
In the room we were look at 79 degrees.
Under the carburetor, while the thing was running
wide open at peak horsepower, it was 43 to 44 degrees.
And in the runner, we saw 68 degrees.
And so it got hotter from underneath the carburetor
than it did in the runner and our belief in that
is because the air speed is the molecules rubbing
into each other and actually causing heat
because of friction. - Yes.
- So I think that's sort of the nutshell
of what we just decided, right?
- [Steve] I'm with you. - I agree.
- And so once again this is wide open
throttle testing, things would be different
at part throttle cruising around.
So the next thing to do is to heat
this thing up to 200 degrees of coolant temp
and see if it gets worse.
(engine revving)