Physical limit to power?
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From: Rockville, MD
Physical limit to power? ok, so i was thinking about how top fuels literally run on the edge of exploding all the time churning out ~10,000hp or so. my question is, is there actually a limit to haow much you can get out of any single engine? i ask because of the pressures in a top fuel will be enough to flash most things to a solid including the fuel inside the motor. any ideas of the actual physical limit to any given engine?
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From: Anna, OH
Originally Posted by 2002_Z28_Six_Speed
Cross-sectional area of the parts surely limits your max power...
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From: Owasso,Ok/Honolulu, HI
i would think that engine size would have alot to do with it as well. wouldn't something smaller be more likely to let go at a lower power level than somethihng bigger? eg. a four cylinder thats only ~120 inches compared to a BBC thats 500+ ci?
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From: Rockville, MD
Originally Posted by lookin4aTA
i would think that engine size would have alot to do with it as well. wouldn't something smaller be more likely to let go at a lower power level than somethihng bigger? eg. a four cylinder thats only ~120 inches compared to a BBC thats 500+ ci?
Yes! Top fuel cars have huge cylinder heads with extra extra long head bolts. You can't do that in a street car. The engine has to be compact and running no where near what it could handle for reliability.
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From: Upstate NY
Originally Posted by Wnts2Go10O
ok, so i was thinking about how top fuels literally run on the edge of exploding all the time churning out ~10,000hp or so. my question is, is there actually a limit to haow much you can get out of any single engine? i ask because of the pressures in a top fuel will be enough to flash most things to a solid including the fuel inside the motor. any ideas of the actual physical limit to any given engine?
Much of the hp comes from the nitro which contains it's own oxygen, The huge blowers are cramming in massive amounts of air and the fuel systems inject enough fuel to "hydrolock" (or completely fill up the area above the piston at top dead center) with liquid fuel. The limit is 85% nitro now, down from 90% a few years ago and unlimited before that. Rpm is limited to about 8400.
Nitromethane has complex chemical reactions when ignited which are more than just burning like gasoline/air mixture. That accounts for much of the power. If they were allowed, they could spin the engines faster, use higher percents of nitro, pump in more air and inject even more fuel and produce more power. Materials technology can keep up with the demands if you spend enough money on them. Rules limits keep the races closer, keep the spending somewhat under control, and still provide an exciting 330 mph 4.5 second show.
Remember a T/F engine running at 8200 rpm from the green light for 4.6 seconds only turns over about 650 total revolutions in anger. That's only 325 firings of each cylinder before a rebuild. Even then losing a cylinder or 2 is common.
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even with more amounts of nitro literally "crammed" into the cylinder you still have a point of absolute saturation in the cylinder where the mix can no longer flow. It used to be normal to see a %95 mix of nitromethane but as you said, the rules now limit the performance through detuning and taking away gear as well. It WOULD be interesting to see just how much a TF motor COULD take at it's absolute limit and actually be able to hook it to the track and get a speed/time. Since there are no dyno's that can handle it you still would need to use the formula manually to get a rough estimate of HP figures and account for drag, tire slip and parasitic loss. I can't even fathom what is pushed of the flywheel on one of those monsters.
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From: Rockville, MD
Originally Posted by Old SStroker
Perhaps Top Fuel engines are closer to 7000 hp than 10, but your point is a good one. The engine builders continue to coax more power out of them, but NHRA limits not only displacement, but now rpm and nitromethane percentage.
Much of the hp comes from the nitro which contains it's own oxygen, The huge blowers are cramming in massive amounts of air and the fuel systems inject enough fuel to "hydrolock" (or completely fill up the area above the piston at top dead center) with liquid fuel. The limit is 85% nitro now, down from 90% a few years ago and unlimited before that. Rpm is limited to about 8400.
Nitromethane has complex chemical reactions when ignited which are more than just burning like gasoline/air mixture. That accounts for much of the power. If they were allowed, they could spin the engines faster, use higher percents of nitro, pump in more air and inject even more fuel and produce more power. Materials technology can keep up with the demands if you spend enough money on them. Rules limits keep the races closer, keep the spending somewhat under control, and still provide an exciting 330 mph 4.5 second show.
Remember a T/F engine running at 8200 rpm from the green light for 4.6 seconds only turns over about 650 total revolutions in anger. That's only 325 firings of each cylinder before a rebuild. Even then losing a cylinder or 2 is common.
Much of the hp comes from the nitro which contains it's own oxygen, The huge blowers are cramming in massive amounts of air and the fuel systems inject enough fuel to "hydrolock" (or completely fill up the area above the piston at top dead center) with liquid fuel. The limit is 85% nitro now, down from 90% a few years ago and unlimited before that. Rpm is limited to about 8400.
Nitromethane has complex chemical reactions when ignited which are more than just burning like gasoline/air mixture. That accounts for much of the power. If they were allowed, they could spin the engines faster, use higher percents of nitro, pump in more air and inject even more fuel and produce more power. Materials technology can keep up with the demands if you spend enough money on them. Rules limits keep the races closer, keep the spending somewhat under control, and still provide an exciting 330 mph 4.5 second show.
Remember a T/F engine running at 8200 rpm from the green light for 4.6 seconds only turns over about 650 total revolutions in anger. That's only 325 firings of each cylinder before a rebuild. Even then losing a cylinder or 2 is common.
Originally Posted by Wnts2Go10O
its hard to imagine the massive pressures they see with nitro.
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From: Laguna Niguel, CA
Originally Posted by bygblok
the static compression ratio changes enough with the growth of the motor under heat but can you IMAGINE the running CR at full boost from the lung and add to that the pressure from the bang??!! I wonder what formula you'd have to use to figure the operating ratio that thing works under. Consider thermal expansion, total growth in internal volume due to the explosion..... holy smokes it'd have to be oh say...... 300.1 or so??
Some of your posts are hard to follow, but they seem to have good information.
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TF is all about controllable hp. Nitro is probably the least understood fuel used today.
Nitro is very load dependent. More load = more HP. Nitro also loves DCR, but hates in in the respect of fuel volume. The hotter the incoming charge, the better. Alot of nitro stuff is oppisite from normal thought. You almost control power level with clutch application. Every tuning choice in T/F is a catch 22, its just a game of who guesses better.
Nitro is very load dependent. More load = more HP. Nitro also loves DCR, but hates in in the respect of fuel volume. The hotter the incoming charge, the better. Alot of nitro stuff is oppisite from normal thought. You almost control power level with clutch application. Every tuning choice in T/F is a catch 22, its just a game of who guesses better.
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From: Upstate NY
Originally Posted by AlkyInMyBlood
TF is all about controllable hp. Nitro is probably the least understood fuel used today.
Nitro is very load dependent. More load = more HP. Nitro also loves DCR, but hates in in the respect of fuel volume. The hotter the incoming charge, the better. Alot of nitro stuff is oppisite from normal thought. You almost control power level with clutch application. Every tuning choice in T/F is a catch 22, its just a game of who guesses better.
Nitro is very load dependent. More load = more HP. Nitro also loves DCR, but hates in in the respect of fuel volume. The hotter the incoming charge, the better. Alot of nitro stuff is oppisite from normal thought. You almost control power level with clutch application. Every tuning choice in T/F is a catch 22, its just a game of who guesses better.
Originally Posted by gun5l1ng3r
Are you saying they have a 300:1 SCR?
Some of your posts are hard to follow, but they seem to have good information.
Some of your posts are hard to follow, but they seem to have good information.
Originally Posted by AlkyInMyBlood
TF is all about controllable hp. Nitro is probably the least understood fuel used today.
Nitro is very load dependent. More load = more HP. Nitro also loves DCR, but hates in in the respect of fuel volume. The hotter the incoming charge, the better. Alot of nitro stuff is oppisite from normal thought. You almost control power level with clutch application. Every tuning choice in T/F is a catch 22, its just a game of who guesses better.
Nitro is very load dependent. More load = more HP. Nitro also loves DCR, but hates in in the respect of fuel volume. The hotter the incoming charge, the better. Alot of nitro stuff is oppisite from normal thought. You almost control power level with clutch application. Every tuning choice in T/F is a catch 22, its just a game of who guesses better.
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From: Laguna Niguel, CA
Originally Posted by AlkyInMyBlood
TF is all about controllable hp. Nitro is probably the least understood fuel used today.
Nitro is very load dependent. More load = more HP. Nitro also loves DCR, but hates in in the respect of fuel volume. The hotter the incoming charge, the better. Alot of nitro stuff is oppisite from normal thought. You almost control power level with clutch application. Every tuning choice in T/F is a catch 22, its just a game of who guesses better.
Nitro is very load dependent. More load = more HP. Nitro also loves DCR, but hates in in the respect of fuel volume. The hotter the incoming charge, the better. Alot of nitro stuff is oppisite from normal thought. You almost control power level with clutch application. Every tuning choice in T/F is a catch 22, its just a game of who guesses better.
Threads like these are great! We are talking about the internal workings of the most powerful IC motors in racing!
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A 2000 lb car (same motor) will accelerate slower than a 3000lb car if everything is the same. Nitro produces its own oxygen as it burns, and more oxygen the faster it burns and the more it is compressed. The dynamics of load are still yet not understood, but its a fact we generally accept(im no scientist). Its hard to describe without a graph(and I cant show those...) Tire speed vs. Track vs. Clutch vs. fuel Volume vs. boost vs weather. More clutch=more power=less traction. So lets kill volume. Lower volume & less timing = dead cylinders=lost round. Now let keep the motor happy and take out clutch. Whoops, bye bye motor. Ok now---Lets keep motor happy, giver some clutch. Tire smoke. ****, these test days cost 7,000 a pass, I better get this right. Ok, screw it all,throw away the data. Take a tooth out, pull timing early, make er thirtsy for fuel until 400ft no clutch until 100ft. All in by 700ft. Pray. Twice. 4.52 at 331... Damn, this is EASY!!!
Anyways, other cool stuff.
9000 psi cyl pressures
8 thou on the rods 6 on the mains
12-14 Gals in 5 secs
sometimes 64 seperate injectors
120 gpm pumps
sometimes less than 1:1 af
70 some deg of advance
Anyways, other cool stuff.
9000 psi cyl pressures
8 thou on the rods 6 on the mains
12-14 Gals in 5 secs
sometimes 64 seperate injectors
120 gpm pumps
sometimes less than 1:1 af
70 some deg of advance
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I would like to see the cam specs on them, im no engine expert, far from it, i just know that somehow they make ~7,000 go 330 MPH in a 1/4 in 4.5 seconds, and are fun as hell to watch, and thats all i need to know, but its fun to read this thread
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From: Decatur IN.
on our alchohol car it is much easier to read the egt's than to go after the plug " but I know alot of guys that still do'' we will pick the plugs first and then go to the race pack, double back to the plugs, then adjust valves as procedure... as far as physical limits of a internal combustion engine..... well you know how the story goes it will never go over 100 miles an hour tops....LOL
oh how the times chandge!
oh how the times chandge!
Originally Posted by Brent@EPP
on our alchohol car it is much easier to read the egt's than to go after the plug " but I know alot of guys that still do'' we will pick the plugs first and then go to the race pack, double back to the plugs, then adjust valves as procedure... as far as physical limits of a internal combustion engine..... well you know how the story goes it will never go over 100 miles an hour tops....LOL
oh how the times chandge!
oh how the times chandge!
