I drive a Top Fuel Dragster - AMA

[u/iluvatar]

I race a Top Fuel Dragster in the FIA European Drag Racing Championships. The numbers are pretty mind-boggling:

• 8500 bhp
• More torque than you can shake a stick at
• Up to 5G acceleration
• 0-100 mph in around a second
• Top speed in excess of 300 mph
• Standing quarter mile in approximately half the time of a modern F1 car

Here's a photo of me in the car at the first round of the FIA championship at Santa Pod Raceway last year.

So, AMA!

Edit: (20:35) I've been at work, but I've got to head home now, so I'll take another look when I get home (about an hour, probably).

[u/SE94]

Hey thanks for doing the AMA. What kind of physical training to do you have to do for the 5G acceleration?

[u/iluvatar → u/SE94]

Not as much as I should :-) The races are obviously quite short, so it's not like a fighter pilot where they need to be in top condition to cope with the acceleration over prolonged periods. But still, my doctor gave me some exercises to try and strengthen the muscles in my lower back, which is where you feel it the most. I do a bit, and should probably do more.

[u/WhatWasThatJustNow]

I've always wondered...

Top Fuel cars are insanely loud from the stands (or further! There's a drag strip about 6mi from my house, and I can hear them clearly on a summer night), so what's it like inside the helmet? I can't imagine normal earplugs are enough....

What's it feel like to blow up an 8500hp engine right over your shoulder?

[u/iluvatar → u/WhatWasThatJustNow]

what's it like inside the helmet? I can't imagine normal earplugs are enough....

Surprisingly not that loud. I don't even wear earplugs. But remember, you have a titanium shield between you and the engine, plus a carbon fibre crash helmet, plus the padding inside the helmet.

What's it feel like to blow up an 8500hp engine right over your shoulder?

There's a thump and it feels like you've been punched in the kidneys. That happened to me last year. The car didn't feel like it was pulling as strongly as it should, and the guy in the other lane was miles out in front and I had no chance of catching him. I lifted off the throttle to try and save parts, but a fraction of a second after I did so, the engine let go. When I got the top end of the track, I tried to get out of the car and realised how much pain I was in. I went to the hospital to check for a broken back (at the insistence of my crew, who had worked for a previous driver who had done just that), but fortunately it was just soft tissue damage.

Rose Hughes captured a photo from the top end of the track on that run. You can see the engine is still smouldering.

[u/Pawy_beingretard247]

How much fuel does that thing consume on a quarter mile?

[u/iluvatar → u/Pawy_beingretard247]

After Scott Kalitta's fatal accident a few years back, the NHRA switched to racing over 1000' for the nitro classes. Here in Europe, we followed suit a couple of years later, so we no longer race over the full quarter. But to get to 1000' takes around 12 US gallons.

[u/Mulsanne]

Can you share a bit about what the ladder is like to get to the level you're at now?

Also what kind of training do you do when you aren't at the track? (I'm wondering specifically if you do anything to hone your reaction time)

[u/iluvatar → u/Mulsanne]

Also what kind of training do you do when you aren't at the track? (I'm wondering specifically if you do anything to hone your reaction time)

There are practice trees you can get to try and work on your reaction time. I tried them, but didn't find they really helped me. You can narrow your field of vision. Some drivers put strips of tape over the sides of their visors to reduce distractions from their peripheral vision, but (so far) I haven't done that. If you're in the US, I can highly recommend going to one of Frank Hawley's reaction time clinics.

[u/iluvatar → u/Mulsanne]

Can you share a bit about what the ladder is like to get to the level you're at now?

Well, in the UK, there are 6 basic sportsman classes. There are 3 fixed index classes - Super Street (10.9s), Super Gas (9.9s) and Super Comp (8.9s) and 3 dial your own classes - Sportsman ET (12s and slower), Pro ET (9s - 11.99s) and Super Pro ET (6s - 8.99s). I raced in all of those at various points except for Super Street.

From there, there are the pro classes - Pro Stock, Pro Modified, Top Methanol (in the US, it's called Top Alcohol) and Top Fuel. The only real barrier to entry into the pro classes is money. I happened to be in the right place at the right time, and was fortunate enough to find some backing to allow me to step up, so it would have been rude for me to say no, really!

Here's a selection of the cars I've driven over the years:

• Dodge Dart

• Chevy Monza

• Chevy Camaro

• 4-link dragster

• Ford Capri

• Another 4-link dragster

• A/fuel dragster

[u/ucantsimee]

If you went to a salt flat and put the hammer down until the car ran out of acceleration, how fast would it go? I know they still have a lot left when they hit 300.

[u/iluvatar → u/ucantsimee]

On the launch, the car is accelerating at around 5G and when it crosses the finish line it's still pulling in excess of 1G which strongly implies there's more to be had. However, the car is designed to run to the distance we race over, so you'd run out of gearing before too long. Further, the engine is under so much stress that it would be unlikely to hold together for much beyond the race distance.

My introduction to Top Fuel was crewing for a guy called Smax Smith. He now races in North America, and a few years back, he had pretty much the worst case scenario - his throttle jammed open. Rumour has it that the data logger showed some ludicrous speed before the engine exploded. 350 mph or something like that?

[u/Wally223]

Why are the front tyres so small?

[u/Gyro88 → u/Wally223]

Cuz they don't make you go faster :)

[u/iluvatar → u/Gyro88]

In simple terms, yes. They're small because if they were bigger, they'd have more friction, which is the enemy of speed! The front tyres are more or less the same size that they've always been, while the rear tyres have grown progressively over the years because you want more friction there.

[u/Mulsanne]

From u/myrk13

Do you plan to come to the US and run a few events in NHRA/IHRA?

There are a number of folks from overseas that come over and it is interesting to talk with/see their interviews at US events.

[u/iluvatar → u/Mulsanne]

To paraphrase both Kevin Costner and Mike Myers, "If you fund it, I will come" :-)

Obviously, I'd love to do it. I have NHRA licenses in both Super Comp and Top Alcohol Dragster (both of which I got at Gainesville through Frank Hawley's racing school), so I don't imagine that upgrading to Top Fuel would be too problematic. But the costs are enormous, and I simply don't have that sort of money.

[u/midshipmen89]

Thanks for the original AMA.

How much "setup" is done on the car from run to run, and weekend to weekend? Aside from the full engine rebuild, do you change anything? Along the same vein, how involved are you with the engineers in setting up the car?

[u/iluvatar → u/midshipmen89]

How much "setup" is done on the car from run to run, and weekend to weekend?

First, a bit of background. A modern nitro car is basically a standard internal combustion engine, which most people can understand. But it's not quite that straightforward. Fuel enters the engine via a pump that's ultimately driven from the crank and so is proportional to engine RPM. There are a number of bleed off mechanisms to prevent the fuel all going into the engine, and the amount of fuel you bleed off back to the tank indirectly affects the amount of fuel that goes into the engine. Traditionally those were fixed amounts governed by timers triggered by a switch under the throttle pedal, but these days we have a continuously variable slide valve to achieve the same thing.

Once fuel is in the engine, it mixes with air and then burns in the combustion chamber to produce power. If we can burn more fuel, we can produce more power. But we need to maintain the right fuel-air ratio, so if we want more fuel, we need more air. The supercharger is basically a big air pump that sits on top of the engine to achieve that.

With fuel and air in the combustion chamber, you can add a spark to make the magic happen. We use variable ignition timing, so we start with a lot of advance to get the car off the line, then retard the ignition to stop it making too much power and spinning the tyres and then bring the ignition back in again later in the run.

Once the engine is turning, we need to get that power to the rear wheels. There is no gearbox, it's just direct drive from the back of the crank to the rear wheels, via a centrifugal clutch. The clutch has many fingers that fly out when it rotates. There are weights on each finger, which affect how quickly that finger will fly out and how much pressure it will exert when it does so. There is also a hydraulic ram, called the clutch canon, that restricts how far the fingers can fly out. By moving the canon throughout the run, we can control how quickly the clutch locks up. We start by slipping the clutch to get the car off the line and then progressively engage more of the clutch until it's completely locked up 1:1 a few seconds into the run and the output shaft is turning at the same speed as the engine.

So, with that in mind, what do we change in terms of setup? There are a number of variables. The quality of the air affects how the fuel will burn and how much power the engine will produce. We use a measure called density altitude, which gives us an indication of how good the air is. Cool, dense air contains more oxygen and so allows us to produce more power per unit volume of air. This is good. We can adjust the size of the pulleys on the crank and on the supercharger to adjust the overdrive ratio to give optimal settings for the air quality.

Another variable is the amount of traction available on the track. Some tracks are better than others, and the condition of the track will change throughout the day, both with the weather and also as more vehicles go down the track and leave rubber behind. You hear about "green tracks" in F1. Well that's far more of an issue in drag racing. The biggest adjustment you can make is with the clutch. Controlling the rate at which the canon moves governs how quickly the clutch will lock up and that can be adjusted to suit the track conditions. You can also adjust the ignition curve and the fuel bleed off as appropriate, and change the weights on the clutch fingers if you need to.

Obviously, it's a balancing act as you need to ensure that you're putting in the right amount of fuel and air, ignited at the right time, for the amount of clutch you're using. Lock the clutch up too soon and you'll pull the engine RPM down and waste the run. Lock it up too late and you won't be getting as much power to the rear wheels as you should be, wasting the run. Tuning the car is a bit of a black art. But when it all comes together, the end result is magical.

What do we change between runs? The regular consumables that you'd expect - fuel and oil. Plus some other things that less extreme forms of motorsport might not deem consumables. Bearings are consumables. Spark plugs are consumables and are changed every run. Even pistons are consumables. We typically don't change them unless we need to, but you'll often find they've nipped a ring after a run, so they'll need to be swapped out. We keep track of the number of runs on each con rod and on the supercharger belts and change those before they wear out (although they'll get more than one run). The supercharger has teflon seals, which need replacing after a few runs. The clutch discs and floaters are changed every run.

[u/ShootUpPot]

I want to ask a clever question but I can't think of one so instead I wonder: what is the fastest top speed you have ever achieved?

[u/iluvatar → u/ShootUpPot]

what is the fastest top speed you have ever achieved?

I'm not entirely sure. The quickest I've been measured through the traps was 269 mph and change, but I was already off the throttle at that point because the car had started shaking, so it was probably around 275ish.

[u/splendidtree]

Hi! You answered one of my questions in r/dragracing so I feel like we're already bros.

As a long time bracket racer (jr drag racing as a kid and now have two cars for Sportsman ET/footbrake and Pro ET) my question is do you have any connection with the ("lowly" :P ) bracket/Sportsman racers over there now that you're pro? Is that how you started? I know a lot of the pros here in the States still bracket race (and/or Sportsman race) frequently (Coughlin, Connolly, Langdon, etc) because of the roots they have starting in those classes.

[u/iluvatar → u/splendidtree]

Yep. After the European Finals last year in the Top Fuel dragster, I went on to race at the UK National Finals a few weeks later in my girlfriend's 17 second daily drive Ford Capri.

A few years back, my financial situation took a turn for the worse, and I had to stop racing for a couple of years. When I resumed, I'd dropped down to the entry level Sportsman ET class. But I ended up having just as much fun as when I was going quicker. Racing's racing at the end of the day.

[u/[deleted]]

Hi! I have a few questions.

What kind of stress do the engines go through?

How many engines do you go through on a weekend and during a year?

Have you experienced any huge crashes or witnessed competitors have a crash, and what's the medical like at track side?

Last question, but you may not have an answer, but, I studied motorsport engineering engineering at college followed by computing, and now computing at uni. What sort of career can I have in motorsport , I tried doing my own research but didn't get much information out from it. Tia.

[u/iluvatar → u/[deleted]]

What kind of stress do the engines go through?

More than you can possibly imagine! Nitromethane is an unforgiving fuel, and if anything goes wrong, it's going to put a lot of stress on the engine. If you have too much fuel in the combustion chamber, it can't compress properly, so your con rods snap on the upstroke. If you have too little fuel, then it burns lean and gets too hot, which burns through the head gasket, the head itself, the block and the piston. Every time you hit the throttle, you're putting a massive load through the crankshaft, which you hope will result in sacrificing a few bearings, rather than damaging the crank, but it's always a risk. If something goes wrong and you need to get off the throttle and back on it again after the car has settled down (known as "pedalling"), then you're putting the same load on the crank for a second time in the run and you're almost certain to have done damage. When it goes wrong, it tends to go wrong in a big way, due to the stresses involved. Here are a couple of examples of the havoc wreaked by nitromethane when something's gone wrong: the A/Fuel dragster I drove in 2013 and The Top Fuel dragster I drove last year. How many engines do you get through? As few as possible! They're not cheap. If all goes well, you can do a whole season on a single engine (in Europe at least - I suspect in the longer NHRA season that's not possible).

I studied motorsport engineering engineering at college followed by computing, and now computing at uni. What sort of career can I have in motorsport

In Europe, you can't be involved in drag racing professionally, because there simply isn't enough money in the sport. I'm a software guy professionally, and drive as a hobby. But there are other forms of motorsport where you can make money at it. The UK in particular is the world centre for motorsport, so there are plenty of jobs around in the "motorsport triangle" in Northamptonshire, Oxfordshire and Buckinghamshire.

[u/empw]

Do you kart or do road racing? Or are you perfectly content drag racing?

I don't mean that to sound rude if it does. Basically I'm asking if you do any other racing.