Hello, everyone and welcome! In this video we're going to be talking about how the Dodge Demon manages such an impressive launch
but we're not really going to just focus on the tires or the engine we're going to talk about two of the different systems
they employ the transbrake and torque reserve both of these basically first for a production vehicle
and so first let's just work through our system here.
Here we have our car starting with the intake leading to our wheels
up front is more of the torque reserve system and then towards the back
once you get to the transmission we get into the transbrake so let's just work our way through this flow
you have your air filter that travels through you're going to pull in that air through a
2.7L supercharger the hellcat has a 2.38L supercharger at 0.8 bar
So this is a 25% increase in boost 14.5 PSI sending that air into the intercooler
then to the throttle then in your 6.2L V8 engine 840 hp 770 lb-ft of torque.
If you're running 100 octane fuel and so torque reserve is going to occur basically right here
where you're going to pre-fill after the supercharger
but before the throttle with 8 PSI of boost and hold your engine RPM between 950 and 2350 RPM
2350 being the stall speed for the torque converter
so what's going on right here the supercharger actually doesn't have a clutch disconnect
so it's always spinning depending on the engine RPM and basically if you don't need boost
let's say you're at half throttle or partial throttle whatever it may be you have a bypass valve that allows that boost to recirculate
back to the intake back inside the supercharger and
so what you're doing at a launch. Let's say you pull up to the drag strip
you're waiting to launch you put it in this torque reserve mode
where you can build up the revs here and build up this boost it closes off this bypass valve
so you don't recirculate that air
and then it uses the fuel flow and the spark timing it retards that timing enough
where you can hold the engine RPM between 950 and 2350 while still maintaining and holding 8 PSI boost,
you know from the intercooler onward
so you've got that boost ready to throw down as soon as you're ready to launch
and then we get in to our transbrake system
so this is interesting because when you're sitting there at the drag strip
and you're about to launch if you have it in this transbrake mode your foot is
not actually on the brake the transmission is actually what's holding it. So your foots already off the brake
and you're just using a paddle shifter to tell it to go and you're modulating your throttle to hold the throttle between 950 and
2350 as mentioned if you get outside of this range
it'll take you out of torque reserve, you can still launch, but you won't have the benefits of torque reserve
so then you have your 8-speed automatic transmission
where that torque is going to and in this transbrake mode what you do you have three clutches basically for every gear
and in order to use any one gear you're going to be using three clutches
this is certainly a simplified drawing
but basically you're going to hold all three
clutches necessary to be in first gear and then you're going to hold one clutch for second gear and because you've got two gears held
you can't accelerate because those fight against each other and so it holds all of that engine torque and prevents the rear from spinning because
the transmission is in two years at the same time now if you're familiar with transbrakes you may say
you know traditionally they tend to use or often they do use first and reverse gear rather than first and second gear.
I asked Dodge why do they do first and second they said it's for safety reasons which makes a ton of sense.
So let's just say hypothetically
something were to fail if you had it in first and reverse
you don't want the car flying backwards when everyone is assuming that if you're about to launch it's going to go forwards
so in the you know
unlikely scenario that the transmission were to fail you're going to have that car no matter what the only direction
it can go is forwards, so that's basically built in safety why they do first and second
but is of course sized and built appropriately to be able to handle that torque and be able to hold the vehicle in place
so when you put it in this drag mode it is pretty cool. All you're basically doing you're holding on to one pedal and
paddle shifter, and you've got your foot on the throttle holding it at a set RPM, whatever RPM
you deem between 950 and 2350 will give you you know maximum power
but also not spin up the tires and so in that mode you're going to
basically release once you get the christmas tree coming down you're going to release your paddle shifter and
as soon as you release that it's immediately sending torque to the rear wheels
so it's pretty cool
you release the paddle your foots not on the brake so you don't have that time that you're moving from the brake pressure
it's just basically Instantaneous
and then you're flying down the drag strip you ease into the throttle of course because you're holding in a set RPM so you release that
pedal you release that paddle and then you ease into the throttle and
continue to fly down and then it starts to shift through the gears
but all it's basically doing when you release that paddle is releasing this single clutch that's holding the transmission in place
so that you can't rotate the rear axle.
So what does all of this add up to? Well Dodge claims that with the transbrake and torque reserve active you get up to
a 120% percent more engine torque than if you didn't have torque reserve
The transbrake also preloads the driveline with torque which leads to full engine delivery of that torque
from the engine to the wheels in just 150 milliseconds
So really fast and that enables you to get a quicker zero to 60 time and also a quicker
quarter-mile time. So very impressive technology. If you guys have any questions or comments feel free to leave them below, thanks for watching!