Nevermind that, I'd be happy if we could stop PEBBLES from cracking my windshield

The COOLEST aero-technologies I'd love to have on the T/A:

1) leadball - radar absorbing paint
2) carbon-fiber frame - again, not radar friendly
3) Electro-magnetic warefare - active jamming equipment

4) micro-perforated leading edge - reduced air drag by 10% by reducing turbulance on leading edges using tiny holes and suction (http://articles.findarticles.com/p/a.../ai_2051217912)
5) micro-blower porous skin - reduced air drag by 50%+ by blowing out of tiny holes along the body suface/skin. (http://gltrs.grc.nasa.gov/reports/1996/TM-107315.pdf)

Considering a 300mph TF car is running at ground level, in an atmosphere between 50*F and 100*F... the speed of sound is 750 to 790 miles per hour. Yep, Top Fuel guys are pushing Mach 0.4! I wouldn't be supprised to see #4 or #5 incorporated into future TF, or even more likely Funny Cars, if it can be intigrated without a weight penalty or rule violation.

 

So there's no quench height at all? Is this an attempt to save the gasket for combustion pressures? hmmm... interesting.

While steel conrods typically require ~0.040" quench gaps (less than 0.020" results in contact from bolt/rod stretch I'm told), aluminum conrods in gas motors have to increase the gap to about 0.060" I'm told due to rod stretch. I'd hate to think how much the rods stretch at 9000 rpms in a TF car!

Quote:

For timing, the mags are typically set at 58-60 degrees and they run what is called a 6 shooter, normally 3 of them at a time (to actually make it a 18 shooter), which works kinda like a 3-step.

I've seen this in photos and always wondered what they did with the other 2 spark plugs. If there are 2 plugs per cylinder, that's only 16 plugs... what to do with the other 2?

 

 

Allow me...

What does one mean when they say, "6 shooter" and "3-Step"?

 

3-step is short for a 3-step rev limiter. You'll more commonly hear the term "2-step" at the track indicating that a car has a low RPM limiter (say 3000rpms) that the driver will "red-line" at for launch, and then after lauch the standard rev limiter (say 6500 or whatever) is used to protect the engine from over-reving as normal. The tip-off to a 2-step or 3-step design is the heavy POPPING sound cars will make at the line... and the nearly perfect rpm control a driver has. Basically it's a ingition-control system to permit perfect launch RPMS, and safe rpms for shiftpoints without the driver doing it himself. 2-steps and 3-steps are not quite considered a "electronics" class item, but some no-electronics (mostly amature) classes ban them anyway (depends on the series). This is standard fair for any pro-series though.

The 6-shooter is a distributor for a single cylinder. I belive the way it works is that each spark plug in the cylinder is fed by 3 wires. One for each rev limit... but it's just a guess, I never quite understood how everthing hooked up. Drag Racer Magazine goes pretty indepth in some of the alcohol and top-fuel rules/building but I don't recall anyone breaking down the ignition setups in detail... I've mostly just seen pictures of them

 

That is very contrary to information Reher Morrison and others have given in regards to PS valvetrain revelations found through Spintron testing. Smooth lifter motion in a PS engine most likely equates to alot of power being left on the table.

I question your information sources..... not likely accurate.

-Mindgame

 

Interesting concepts Steve.

1) for stealth you need lots more than RAM (radar absorbing material). Primarily you need to do a combination of things like deflecting the radar beam with either faceted (F-117A) or appropriately curved surfaces (B-2 and beyond), absorb some of it with RAM, and be invisible to the naked eye aiming the radar gun. That's the tough part, IMO.

2) If you do 1) correctly it doesn't matter much what's under the skin.

3) Jamming, depending on how you do it, ain't cheap, and while it might blot out your speed reading, it could very well point out to the operator which vehicle is jamming and you might be in bigger trouble. Deception, as in changing the speed read on the gun is possible, but if the gun reads 55 and you have 30 mph overtake on the surrounding traffic, you are easy to pick out.

4), 5) etc. Doesn't some of this do best at airspeeds quite a bit higher than 100 mph? The mechanism needed would probably weight more than enough to offset much gain. You'd need to be very **** about removing all the squashed bugs which disrupt the laminar flow you are probably trying to achieve. Good sailplanes lose a considerable amount of glide ratio if they accumulate bugs on the leading edges during a long flight.

TF dragsters have a terrible Cd. Even worse is the induced drag from the 4000+ lbs of downforce from the rear wing at speed. FC have about the same downforce, or perhaps more especially at the front (shorter wheelbase needs more).

Just my guess, but I don't see blown leading edges, etc. becoming significant in TF or FC. I do think aero drag refinement is very important in Pro Stock, however.

My $.02. Your opinion may vary.

 

I think I'm more confused about these motors after reading this
thread.

When I did talk to the TF technician, he answered several questions
and let me take video close up. I have photos of the valve train
and he specificially told me the rocker ratio was 1.7:1

"IF" the valve lift was only 0.500", why would someone choose
to install a 1.7:1 ratio rocker when a 1.5:1 would suffice?

This would go against efficiency of the valve train geometry as
we know it. I can achieve over half inch lift with a 1.5:1 rocker
and a 292H Comp Cam.

I would imagine these TF motors use a large base circle cam with
potentials of one inch lifts or more with such a high rocker ratio?

 

Not quite, Steve. The pretty much 2 ignition systems. 2 coils, 2 44amp magnetos, and 2 sets of plugs and wires (2 each per cylinder). The mags are then controlled by the Timing control box (looks like a small 6A ignition box), to which the Six Shooters are plugged into. Most teams now use 3 Six Shooters wired in Series. That effectively means they can control (change) the timing up to 18 times during the run. Here is MSD's picture and decription: http://www.msdpromag.com/ Click on 'Products' on the left, then select 'Six Shooter' under 'Timing Controls'.

 

Well, Pro Stock engines are about as far from a fuel motor as an engine in a stock 3rd gen is.

Question me all you want-I don't care. I have my sources.

 

Ok, I have to admit, I was wrong about the cam specs. Specifically the lift #'s. It has been a year and a half since I built a fuel shortblock and couldn't quite remember the specs. I found this on Crane's website, it is an old-school fuel cam that is a little different than today's 'stock' cam, but the lift #'s are the same. Where it differs is the duration (today's 'stock' cam is 298/298), and the spring pressures. The guys in the nostalgia (sp?) series run this cam:fuel cam
Different teams run different rockers (along with different lobe lifts), for different reasons, like I said before. The team you talked to Zero_to_69 probably does run a 1.7 rocker on the intake. Others run 1.6's. They do usually run a smaller ratio on the exhaust, like a 1.5.

 

Stealth? yes... reduced radar signature? maybe not. Car & Driver did a article on reducing radar signatures and managed to make a C4 vette drop the radar gun's effectiveness until less than 400 feet... well shorter than a radar detector gives you sensing abiilty. Increasing the gap is the goal really. Ditiching a front plate, and opting for a Firebird or Vette with hide-away lights gets you much farther ahead in this respect... a flat black RAM coating would do nicely as well (I mentioned leadball mostly because it's common knowledge it exists but in the past 40 years I'm sure there's much better stuff out there.

Screw the $4000 Mystic-color dealer options... if GM offered a "reduced signature" paint scheme they'd make a bundle (and probably be sued like crazy).

[quote]2) If you do 1) correctly it doesn't matter much what's under the skin. true, although a there's more than radar benefits so it would still be trick to see a CF cabin or subframe design (outside of 6-digit exotic cars)... some day though.

Quote:

3) Jamming, depending on how you do it, ain't cheap, and while it might blot out your speed reading, it could very well point out to the operator which vehicle is jamming and you might be in bigger trouble. Deception, as in changing the speed read on the gun is possible, but if the gun reads 55 and you have 30 mph overtake on the surrounding traffic, you are easy to pick out.

lol.. I was kinda joking on this one. using an electronic warfare package would probably fry any electronics the car runs unless you spent mucho bucks doing it.... and you'd stand out like a sore thumb if you did this as a "always" on measure. Better option is probably to extend the detection to speed lock distance using #1.

Quote:

4), 5) etc. Doesn't some of this do best at airspeeds quite a bit higher than 100 mph? The mechanism needed would probably weight more than enough to offset much gain. You'd need to be very **** about removing all the squashed bugs which disrupt the laminar flow you are probably trying to achieve. Good sailplanes lose a considerable amount of glide ratio if they accumulate bugs on the leading edges during a long flight.

yeah, TF would probably be a waste, but Funny Car might have use for it... especially some the passive versions that use micropores as pass-though channells... assuming you could redirect the "absorbed flow" from the pressure areas to the low-pressure zones farther back in the skin it may actually be something to look as. I dunno... NHRA has never been know for their "cost effectiveness" give it a couple years an aero-designs may get into areas like this.

I'd bank on F1 being there as well, but their speeds rarely exceed 180 or so, and when they do it's briefly. 300 mph dragsters have potential as they are traveling about mach 0.4 at the end of the run. That last half which is aroudn 0.3 to 0.4 mach is actually shown in the links I posted to have ~50% reduction in drag at 0.3 and above... of course that's with active systems, but it may be doable. I don't know what a funny car's or pro-stock drag cf is, but I'd wager even a 5% drop would be substancial when races can come down to a few thousandths of a second.

Interesting ideas though... and there's a bunch more out there I imagine... aero-space has some interesting stuff to play with if someone wanted to spend the cash to do so.

 

Yeah, they're different and I made a mistake after reading through all the replies because when I posted mine, I was under the assumption that we were talking PS.

I'll still stand on the comments I made. PS or TS doesn't matter much... we're still talking about engines that need to make as much power as they can a 1/4-mile at a time. Smooth lifter motion may be important for endurance engines but you're just giving up power at the strip subscribing to that philosophy. We're gonna replace those valvesprings every run anyways.

I'm curious, who's heads were you guys running?

-Mindgame

 

Everyone who is "concerned" about the small cam used in a fuelie remember - it is a FUELIE engine. The blower pumps a lot of air in even with a "small" cam and the fuel provides a lot of the oxygen needed for combustion. I don't remember what the air:fuel ratio is for proper burning of nitromethane but it ain't anywhere near the same as gasoline. Something around 6:1 or less air:fuel sticks in my mind.

 

Steve,
A hemi doesn't have a quench area like a wedge head engine.