NHRA, Another Big Funny Car "Boomer" Today

[Jeff Higgins]

Wow. Hat's of to Daniel Wilkerson. Like the announcer says, "he never stopped driving that car".

Kind of a back story here that the announcer briefly touched upon. NHRA had mandated a form of body retention this year that had the drivers pretty widely upset. Ron Capps has been the most vocal about it. Essentially, the NHRA maintains their system is for spectator safety, to keep departing Funny Car bodies out of the grandstands. Which has simply never happened in the history of the sport. The drivers maintain that the NHRA system keeps too much of the body on the car, in front of them, so they cannot see. Capps, Wilkerson, and others have been allowed to experiment with their own retention systems. I'm not sure Wilkerson's worked as intended, it looks like too much of the body blocked his view. But at least it wasn't the entire front of the car up in his face. Capps lost a body a week or two ago and had a "better" outcome, if you could call it that. No real way to test this stuff, though.

[HobieMarty]

Fantastic driving!!!

Sent from my SM-S916U using Tapatalk

[herr_oberst]

That was a lot of fire. I'm glad the firesuit held. Scary ****.

Speaking of Capps, this is his car a couple of weeks ago. Talk about calm under pressure, and check out the way the parachute carries the rear end off the ground for about half the track!

[Jeff Higgins]

Yeah, that is the Ron Capps incident to which I referred. Like I said, his outcome was "better", if you can call it that.

Pretty amazing how high the 'chutes lifted the rear of his car. Even more amazing was how he held onto it. Remember - in both cases, we are looking at somewhere around 300 mph when this happened.

Capp's explosion was a real head scratcher. It just happened with no warning. In Wilkerson's, we see the more typical chain of events. You can see where it loses traction, then drops cylinders, then goes "boom".

The rear end hops as it loses traction through tire shake, the motor over-revs, spark plugs fail under the increased fuel load and boost, cylinders quit firing, and all that unburnt fuel has to go somewhere - right past the rings into the crankcase.

These are cave man crude machines. Fuel is delivered through two mechanical pumps with no regulation beyond engine RPM. Boost is delivered via a mechanical supercharger, again with no regulation beyond engine RPM. Fuel delivery and boost are both entirely dependent upon RPM. When it suddenly over-revs, both arrive in excess, and spark plugs get welded shut. Now you have no spark coupled with excessive fuel delivery and boost, driving it all past the rings. With even one cylinder still lighting, its blowby lights the charge in the crankcase, and the rest is history.

Watch right before Wilkerson's explosion, and you will see the fire going out on multiple cylinders. Their exhaust pipes look like garden sprinklers. That white/gray mist is the fuel being pumped out the exhaust port, signifying a "dropped" cylinder. Remember, these things run a roughly 2:1 A/F ratio, with the stoichiometric ratio of pure nitromethan at 1.7:1. They can do that because nitromethane releases an oxygen molecule when it burns, so it doesn't need nearly the A/F ratio of gasoline. They run 90% nitro, 10% methanol, thereby the 2:1 ratio. So, yeah, some of the fuel is going out the pipes. The rest goes into the crankcase. Once you see that, the result is inevitable.

[masraum]

It's a very complex situation, and I'm not an expert, but I feel like the big piece of the body that was right in front of the driver may have exacerbated the fireball that seemed to be concentrated behind the piece of bodywork, like it was in a vortex or disturbed or calmer air behind that "wall" which allowed or caused the fire to concentrate seemingly right on the driver (doesn't seem very safe).

[Jeff Higgins]

Something went wrong with the onboard fire suppression. These things have enough of that to save a sinking aircraft carrier. You'll notice that the announcer mentioned several times how unusual it was to have such prolonged fire onboard of one of these cars. The fuel, unlike gasoline, will not burn in an unconfined space. It's actually pretty darn hard to light the stuff. The cars can't even start on it. When you see the guy squirting fuel into the throttles to start the motor, that is actually gasoline. It has to run on that to build some heat before it will run on the nitro mix. That had to be oil that was sprayed around when the top of the motor popped off. When that happened, the car should have been engulfed in suppressant. It wasn't. Might be part of why he was so angry.

[thingmon]

Originally Posted by Jeff Higgins

Something went wrong with the onboard fire suppression. These things have enough of that to save a sinking aircraft carrier. You'll notice that the announcer mentioned several times how unusual it was to have such prolonged fire onboard of one of these cars. The fuel, unlike gasoline, will not burn in an unconfined space. It's actually pretty darn hard to light the stuff. The cars can't even start on it. When you see the guy squirting fuel into the throttles to start the motor, that is actually gasoline. It has to run on that to build some heat before it will run on the nitro mix. That had to be oil that was sprayed around when the top of the motor popped off. When that happened, the car should have been engulfed in suppressant. It wasn't. Might be part of why he was so angry.

Dang, didn't realize the stoichometric ratio was that different..

[herr_oberst]

An interesting fact about an oildown, the NHRA can impose a point deduction and a fine for the cleanup, and this is in addition to the 60 or 70 grand for the cost of the engine, and another 60 or 70 grand for the cost of the body. Ka-ching.

That fire probably required building up a whole new chassis from the spares they keep on the trailer; a lot of work for the crew.

[JackDidley]

Scary ! Nothing funny about driving a funny car.

[Jeff Higgins]

They all bring an extra chassis, along with two or three bodies. The Top Fuel teams bring at least one entire extra car. The car itself is actually relatively "cheap" by pro racing standards. They are pretty darn simple. The tubular chassis is actually considered a "wear item", I don't think they last a dozen runs. They just start cracking welds and stuff, it's cheaper and safer to build a new one than to chase that.

The motors get repaired. The crank, rods, camshafts, and other such items are rarely harmed. The blocks get welded back together and remachined. That's simpler than it sounds, since they are now made without water jackets. So, in the end, most of the stuff is salvageable and is reused.

[masraum]

Originally Posted by Jeff Higgins

Something went wrong with the onboard fire suppression. These things have enough of that to save a sinking aircraft carrier. You'll notice that the announcer mentioned several times how unusual it was to have such prolonged fire onboard of one of these cars. The fuel, unlike gasoline, will not burn in an unconfined space. It's actually pretty darn hard to light the stuff. The cars can't even start on it. When you see the guy squirting fuel into the throttles to start the motor, that is actually gasoline. It has to run on that to build some heat before it will run on the nitro mix. That had to be oil that was sprayed around when the top of the motor popped off. When that happened, the car should have been engulfed in suppressant. It wasn't. Might be part of why he was so angry.

Right. For these insane vehicles, their fuel is probably the equivalent of 500 octane. I've read those "top fuel dragster facts that will amaze you" things that say that part way down the track, they are basically running like a diesel due to heat and compression with no spark source.

I watched drag racing when I was much younger because dad did. I haven't watched it in decades, and am amazed when I hear the modern speeds and ETs.

[JackDidley]

There is nothing like the feeling of being near a fuel car when they start up. Ive been to the US nationals a few times and it is always a good time. Had one explode an engine about 40 feet from me and it was violent. The crankshaft was hanging out under the block.

[red 928]

Most people can't imagine going over 300 mph in a car,
the idea of having it explode at over 300 mph and block your view while you try to keep the rubber side down is too much to contemplate.
Once would be enough for me.

[thingmon]

Reminds me of my ex... 🫣