How Much Power Does A Top Fuel Dragster Make?

"tromoly" (tromoly)
11/24/2015 at 11:14 • Filed to: Top Fuel Dragster, Data Acquisition, DSR Racing, Nitromethane

For years bench racers on the Internet have speculated about how much power a Top Fuel Dragster actually makes. The speculation is further compounded by the fact that most engine dynos cannot contain the power produced by the modern Nitromethane-fed engines, leading some to claim the power numbers are as high as 10,000 horsepower and others claiming as low as 7,000 horsepower. The biggest impact has been felt by Crew Chiefs when setting up for a race weekend, estimating the engine power to be lower than the actual power production causes precious qualifying runs to be wasted finding a setup that worked on that particular track. In modern times with data acquisition monitoring surely engine horsepower could be found during real-world testing, giving Crew Chiefs engine data for better and more consistent tuning and giving the Internet bench racers a more accurate horsepower number to throw around.

Back in October, a group led by Race Engine Technology magazine stayed behind in Reading, Pennsylvania to get a real engine power number once and for all. A torque sensing coupler developed by AVL Racing was placed between the clutch pack and rear pumpkin on the US Army DSR Racing Top Fuel Dragster, this sensor allowed for direct torque measurement being fed to the rear tires and along with the always-monitored engine RPM allowed for a simple calculation of engine horsepower. The following video gives further detail on the testing equipment, a small peek into the data acquisition systems utilized on modern dragsters, and of course gives the ultimate power number found through testing.

DISCUSSION (11)

HammerheadFistpunch > tromoly
11/24/2015 at 11:22

When you posed the question the solution that is being used immediately came to mind: there are plenty of torque measuring tools that are small and can handle massive torque loads. I’m actually amazed this HADN’T been happening for years.

LuczOr > tromoly
11/24/2015 at 11:33

The best part is that these measurements are certainly lower than actual horsepower potential. Torque works in a curious way: if you are measuring torque between a source and a resisting torque, the lower value is what is measured. In other words, this torque sensor (which measures between the engine and the tires) is actually measuring the torque the tires are putting to the ground.

Tires always have some slip (especially in top fuel) so there is a loss in this measurement. The reason an engine dyno is accurate is because the machine can resist 100% of the torque delivered by an engine.

BigBlock440 > tromoly
11/24/2015 at 11:45

I can’t watch the video, but what happened?

Also, that’s pretty expensive just to answer a question.

tromoly > BigBlock440
11/24/2015 at 12:07

To TL;DR the video (you should still watch it, there’s some good info there), the peak power was around 10k horsepower.

In a way yes it’s expensive, but having that power number now allows the Crew Chief to tune better for the track. There are quite a few times when teams will stay on-site the Monday after a National weekend and test, to me this is not different.

BigBlock440 > tromoly
11/24/2015 at 12:10

I will, it’s just blocked at work. Thanks.

tromoly > LuczOr
11/24/2015 at 12:11

Right, this data is IMO more useful than measuring on a dyno because the losses in the clutch pack are already taken into account, meaning one less variable is needed in the vehicle dynamics equations.

I believe tire slip is already measured, there are wheel speed sensors on the front and rear wheels so that can be accounted for.

No doubt an engine dyno gives the most accurate engine power, but when you’re making more power than a dyno can handle this is a good solution.

tromoly > HammerheadFistpunch
11/24/2015 at 12:11

Same here, especially with everything else that’s already measured during a run.

JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t > tromoly
11/24/2015 at 12:30

Kinja'd!!!

tl;dw

I beleive that counts as “impressive”.

LuczOr > tromoly
11/24/2015 at 13:12

Yeah, this is definitely the more useful number. However, I don’t think making a dyno for these engines would be too hard. Here’s the torque measuring device already, now we just need the mechanism to resist tens of thousands of horsepower, lol.

asenna > tromoly
11/24/2015 at 13:38

I cannot believe that they have not dyno’d any of these engines even if they had to build a special dyno to handle the power they would do it.

tromoly > asenna
11/24/2015 at 14:43

At the same time, with the amount of power available that is certainly more than the track can take during most of a run, is it really necessary to have a power number? Personally I see this being used more for clutch engagement tuning rather than engine power, being able to see the torque curve as a function of clutch setup is more useful than raw engine power.

It’s cool to have a definitive power number, but not always necessary.