# Spitting in supercharger intake in Mad Max Fury Road **URL:** \ **Category:** Factual Questions\ **Created:** [August 3, 2016, 7:25am UTC](https://boards.straightdope.com/t/spitting-in-supercharger-intake-in-mad-max-fury-road/761616 "2016-08-03T07:25:02Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![coremelt](https://avatars.discourse-cdn.com/v4/letter/c/4491bb/32.png) [@coremelt](https://boards.straightdope.com/u/coremelt)\ **Post date:** [August 4, 2016, 2:00am UTC](https://boards.straightdope.com/t/spitting-in-supercharger-intake-in-mad-max-fury-road/761616/21 "2016-08-04T02:00:47Z")
> [@dracoi](#): > > It’s not even a whole movie, just a three-hour chase scene. Ain’t nothing wrong with that, if its a well executed, entertaining chase scene. As for it being mostly practical effects rather than CGI this is true. A far higher percentage was done practically than is the norm nowadays. Heres a youtube showing before / after shots with no CGI: [![]( " - YouTube") ](https://www.youtube.com/watch?v=ent02yItm60) ---
**Author:** ![stanger](https://avatars.discourse-cdn.com/v4/letter/s/7ba0ec/32.png) [@stanger](https://boards.straightdope.com/u/stanger)\ **Post date:** [August 4, 2016, 3:00am UTC](https://boards.straightdope.com/t/spitting-in-supercharger-intake-in-mad-max-fury-road/761616/22 "2016-08-04T03:00:33Z")
When I watched _Fury Road_, I automatically shut down the logic and mechanical sections of my brain and just sat back and enjoyed the movie. I was expecting to lots of crazy vehicles, wild stunts, insane mutants and costumes, and a great deal of 'splosions. The movie did not disappoint. But looking at it more critically as discussed above, I really don’t have to stretch the afore-mentioned critiques very far to fit them into reality. Sure, you don’t see clutch-drives used on Roots style blowers on hot rods today – it would be impractical due to the amount of stress handled by the clutch twisting the rotors in a big Roots – but that doesn’t mean it couldn’t be done. If the blower wasn’t all that big, and wasn’t overdriven too much for huge power gains, a clutch drive could be technically possible, if not reliably practical. With the blower “turned off”, there would be enough leakage through the unit for the car to run, but it would significantly cut down the effective power over a simple normally aspirated version of the motor. The unit would also freewheel, but again, with considerable restriction and power loss. I got the impression that they were trying to up the power a bit because the engine was running hot and/or too lean, so they were trying a little “orally induced intercooling” to help out. Engines make more power when they run a bit on the lean side, but they also make more power when running cool. This engine was probably down on power due to 1) really hot intake air, 2) lean operating conditions under boost, 3) questionable quality of fuel during post-apocalyptic times. Introducing fuel into the air intake, even as crudely as shown in the movie, would have helped lower the intake charge temperature and richen up the combustion mixture enough to cool the process and cut down on detonation and the resulting power losses. Then again, the whole “spitting fuel into the supercharger” sequence was really just a cool addition to an lovely over-the-top movie, and appeared to be plausible enough and original enough to catch mentions at the watercooler. And there was also Charlize Theron, who, even though she was shorn bald and sweaty and streaked with heavy eye shadow, still looked mighty fine to this old boy. ---
**Author:** ![Hail\_Ants](https://avatars.discourse-cdn.com/v4/letter/h/dc4da7/32.png) [@Hail\_Ants](https://boards.straightdope.com/u/Hail_Ants)\ **Post date:** [August 4, 2016, 10:21am UTC](https://boards.straightdope.com/t/spitting-in-supercharger-intake-in-mad-max-fury-road/761616/23 "2016-08-04T10:21:50Z")
> [@stanger](#): > > And there was also Charlize Theron, who, even though she was shorn bald and sweaty and streaked with heavy eye shadow, still looked mighty fine to this old boy. You forgot to mention her CGI robot-arm\*!\* In terms of the silliness of the film overall, the main villain looked ridiculous. It looked like they came up with him by having a cosplay contest at Comic-Con and the most enthusiastic/pathetic fanboy kit-bash wank won. The whole movie had this look, over-the-top silliness with not even the remotest thought to practical reality. What was the point of the milking titty-women? Or the water being released from the top of a huge cliff? Freakazoid controlled the water? Ok, but how the hell did he do that?! Where the hell did the water come from? This is the setup/premise of the whole chase scene later, so if we don’t know/care about these things who gives a shit about why they’re being chased?!? This is Storytelling 101 stuff. _The Road Warrior_ struck a perfect balance of enough flash while still having function. This _Mad Max_ was like watching a live-action Saturday morning cartoon. It stopped just short of having cars drive off cliffs and not start falling until the driver had realized it (accompanied with xylophone music). I gave up completely when the enemy pursuit team included that flatbed truck with the guy playing the flamethrower-guitar. Excuse me?!? No. It’s still supposed to be a post-nuclear wasteland. So just, no. ---
**Author:** ![Robot\_Arm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robot_arm/32/18280_2.png) [@Robot\_Arm](https://boards.straightdope.com/u/Robot_Arm)\ **Post date:** [August 4, 2016, 1:46pm UTC](https://boards.straightdope.com/t/spitting-in-supercharger-intake-in-mad-max-fury-road/761616/24 "2016-08-04T13:46:16Z")
> [@Hail\_Ants](#): > > You forgot to mention her CGI robot-arm\*!\* What? ---
**Author:** ![Kobal2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kobal2/32/20_2.png) [@Kobal2](https://boards.straightdope.com/u/Kobal2)\ **Post date:** [August 4, 2016, 3:25pm UTC](https://boards.straightdope.com/t/spitting-in-supercharger-intake-in-mad-max-fury-road/761616/25 "2016-08-04T15:25:11Z")
Charlize Theron did not actually go through limb removal for the needs of the movie. These actresses, you know, so high maintenance ! So they painted her arm blue throughout the shoot, then edited in a gnarly prosthetic with CGI. ---
**Author:** ![Duke\_of\_Rat](https://avatars.discourse-cdn.com/v4/letter/d/ad7895/32.png) [@Duke\_of\_Rat](https://boards.straightdope.com/u/Duke_of_Rat)\ **Post date:** [August 4, 2016, 3:37pm UTC](https://boards.straightdope.com/t/spitting-in-supercharger-intake-in-mad-max-fury-road/761616/26 "2016-08-04T15:37:01Z")
I thought it was nitromethane they were spitting, and spitting nitromethane into the blower would increase the RPMs. When I was a kid I did the exact same thing with model airplane fuel into the intake of a lawn tractor. The RPM revved so high I thought it would blow up before it resumed normal operation. Spraying ether around the intake of a car engine is a way to detect vacuum leaks, the RPM will increase significantly if ether is sprayed onto a vacuum leak. As for spraying fuel into the roots blower, that is how top fuel drag racing engines are started, the mechanic squirts a stream of gasoline directly into the butterflies of the blower until ignition is achieved. Nothing about that scene seemed wrong from a technical standpoint IMHO. ---
**Author:** ![muldoonthief](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/muldoonthief/32/3188_2.png) [@muldoonthief](https://boards.straightdope.com/u/muldoonthief)\ **Post date:** [August 4, 2016, 3:49pm UTC](https://boards.straightdope.com/t/spitting-in-supercharger-intake-in-mad-max-fury-road/761616/27 "2016-08-04T15:49:46Z")
> [@pulykamell](#): > > I haven’t seen the movie, but I’ve heard nothing but good things about it. Also, [read here under “critical reception” and "accolades.](https://en.wikipedia.org/wiki/Mad_Max:_Fury_Road) It seems to be an almost universally praised movie. And it won six academy awards (although those were for technical things.) I want to see it now to see why there is such a gulf between critical opinion and the dopers in this thread. Check out the [original Cafe Society thread](http://boards.straightdope.com/sdmb/showthread.php?t=743150&highlight=chrome&page=5) for plenty of dopers heaping on the praise this movie deserved. And while the Oscars it won were mostly for technical categories, it was nominated for 3 majors - best picture, best directing, best cinematography. ---
**Author:** ![JKilez](https://avatars.discourse-cdn.com/v4/letter/j/e5b9ba/32.png) [@JKilez](https://boards.straightdope.com/u/JKilez)\ **Post date:** [August 4, 2016, 4:57pm UTC](https://boards.straightdope.com/t/spitting-in-supercharger-intake-in-mad-max-fury-road/761616/28 "2016-08-04T16:57:26Z")
[quote=“coremelt, post:21, topic:761616”] Heres a youtube showing before / after shots with no CGI: [/QUOTE] One thing is obvious from that clip is that they must have CGI’d or composited in the actor’s faces in many of the scenes because during the actual shots, no one could keep their eyes open due to all the wind and dust. ---
**Author:** ![fstbk1968](https://avatars.discourse-cdn.com/v4/letter/f/3bc359/32.png) [@fstbk1968](https://boards.straightdope.com/u/fstbk1968)\ **Post date:** [August 4, 2016, 5:29pm UTC](https://boards.straightdope.com/t/spitting-in-supercharger-intake-in-mad-max-fury-road/761616/29 "2016-08-04T17:29:01Z")
> [@stanger](#): > > …With the blower “turned off”, there would be enough leakage through the unit for the car to run, but it would significantly cut down the effective power over a simple normally aspirated version of the motor. The unit would also freewheel, but again, with considerable restriction and power loss… Sorry I must disagree with you here. A blower builds pressure by counter-rotating blades. If enough air leaked past the rotors for an engine to run, the blower would be virtually ineffective at building pressure. In freewheeling mode the throttle response would so sluggish (due to a relatively weak vacuum signal trying to accelerate the mass of the rotors) that it would render acceleration almost non-existent. Stomping on the gas would create a massive bog/stumble as the fuel increases but not the incoming air. ---
**Author:** ![Robot\_Arm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robot_arm/32/18280_2.png) [@Robot\_Arm](https://boards.straightdope.com/u/Robot_Arm)\ **Post date:** [August 4, 2016, 5:59pm UTC](https://boards.straightdope.com/t/spitting-in-supercharger-intake-in-mad-max-fury-road/761616/30 "2016-08-04T17:59:50Z")
> [@Kobal2](#): > > Charlize Theron did not actually go through limb removal for the needs of the movie. These actresses, you know, so high maintenance ! So they painted her arm blue throughout the shoot, then edited in a gnarly prosthetic with CGI. Got any pictures? Maybe it’s somebody I know. ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [August 4, 2016, 7:03pm UTC](https://boards.straightdope.com/t/spitting-in-supercharger-intake-in-mad-max-fury-road/761616/31 "2016-08-04T19:03:42Z")
> [@Duke\_of\_Rat](#): > > I thought it was nitromethane they were spitting, and spitting nitromethane into the blower would increase the RPMs. When I was a kid I did the exact same thing with model airplane fuel into the intake of a lawn tractor. The RPM revved so high I thought it would blow up before it resumed normal operation. Spraying ether around the intake of a car engine is a way to detect vacuum leaks, the RPM will increase significantly if ether is sprayed onto a vacuum leak. As for spraying fuel into the roots blower, that is how top fuel drag racing engines are started, the mechanic squirts a stream of gasoline directly into the butterflies of the blower until ignition is achieved. > > Nothing about that scene seemed wrong from a technical standpoint IMHO. that’s dangerous unless you know what you’re doing. nitromethane requires such rich air:fuel mixtures (1.7:1 is stoichiometric, top fuelers run even richer) that you risk detonation running it in a gas engine. plus, it’s so inherently prone to detonation that it has no octane rating. ---
**Author:** ![Duke\_of\_Rat](https://avatars.discourse-cdn.com/v4/letter/d/ad7895/32.png) [@Duke\_of\_Rat](https://boards.straightdope.com/u/Duke_of_Rat)\ **Post date:** [August 4, 2016, 7:17pm UTC](https://boards.straightdope.com/t/spitting-in-supercharger-intake-in-mad-max-fury-road/761616/32 "2016-08-04T19:17:59Z")
> [@fstbk1968](#): > > Sorry I must disagree with you here. A blower builds pressure by counter-rotating blades. If enough air leaked past the rotors for an engine to run, the blower would be virtually ineffective at building pressure. In freewheeling mode the throttle response would so sluggish (due to a relatively weak vacuum signal trying to accelerate the mass of the rotors) that it would render acceleration almost non-existent. Stomping on the gas would create a massive bog/stumble as the fuel increases but not the incoming air. I didn’t think it (clutch) would work, yet here’s an old thread on the subject: > **[Supercharger with a clutch?](https://boards.straightdope.com/sdmb/showthread.php?t=144581)** > > OK, it’s now possible to have a supercharger that can “be switched on and off” (some Toyotas). How does it work? I mean, what happens to the intake air and fuel when the blower is not engaged? Do the rotors just freewheel to let the intake charge... When top fuel cars throw the blower belt, those engines stop making power right away, and I tend to agree with post #8 in the linked thread. FWIW, here's the original Mad Max where he "engages" the blower. Look at 1:26, the belt and blower drive pulley (or blower shaft) aren't turning. So the arguments for the blower freewheeling via clutch when not in use are off. Nothing in the blower drive is turning before. So even if the clutch was down on the crankshaft pulley, a Roots blower won't bypass enough air with the vanes locked for the engine to run. They could have rigged an air bypass that let air into the intake when the belt wasn't turning, I guess. ---
**Author:** ![Duke\_of\_Rat](https://avatars.discourse-cdn.com/v4/letter/d/ad7895/32.png) [@Duke\_of\_Rat](https://boards.straightdope.com/u/Duke_of_Rat)\ **Post date:** [August 4, 2016, 7:20pm UTC](https://boards.straightdope.com/t/spitting-in-supercharger-intake-in-mad-max-fury-road/761616/33 "2016-08-04T19:20:12Z")
> [@jz78817](#): > > that’s dangerous unless you know what you’re doing. nitromethane requires such rich air:fuel mixtures (1.7:1 is stoichiometric, top fuelers run even richer) that you risk detonation running it in a gas engine. plus, it’s so inherently prone to detonation that it has no octane rating. Well, they were locked in a pitched battle with a hostile force, and IIRC one of the engines did blow. So yeah, it was one of several dangerous things happening right about then. ---
**Author:** ![muldoonthief](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/muldoonthief/32/3188_2.png) [@muldoonthief](https://boards.straightdope.com/u/muldoonthief)\ **Post date:** [August 4, 2016, 7:58pm UTC](https://boards.straightdope.com/t/spitting-in-supercharger-intake-in-mad-max-fury-road/761616/34 "2016-08-04T19:58:11Z")
> [@JKilez](#): > > One thing is obvious from that clip is that they must have CGI’d or composited in the actor’s faces in many of the scenes because during the actual shots, no one could keep their eyes open due to all the wind and dust. Saying there was no CGI in the movie is an exaggeration. It’s absolutely true that most of the car stunts are practical effects, and every vehicle you see really was tooling around the Namibian desert a few years ago. But the storm, and closeups of people inside or on moving vehicles were mostly done in front of green screen with the background added - there’s a lot of that in the deleted scenes & “making of” features on the blu-ray. ---
**Author:** ![coremelt](https://avatars.discourse-cdn.com/v4/letter/c/4491bb/32.png) [@coremelt](https://boards.straightdope.com/u/coremelt)\ **Post date:** [August 5, 2016, 2:11am UTC](https://boards.straightdope.com/t/spitting-in-supercharger-intake-in-mad-max-fury-road/761616/35 "2016-08-05T02:11:58Z")
> [@muldoonthief](#): > > Saying there was no CGI in the movie is an exaggeration. It’s absolutely true that most of the car stunts are practical effects No one ever said there was no CGI. There was over 2000 digital VFX shots. See here: > **[A graphic tale: the visual effects of Mad Max: Fury Road](https://www.fxguide.com/fxfeatured/a-graphic-tale-the-visual-effects-of-mad-max-fury-road/)** > > Find out how the more than 2000 VFX shots in George Miller's Mad Max: Fury Road were created. The difference is that most modern action block busters like the transformers series, or marvel films, they do the cars and explosions completely CGI for massive action sequences. Or rather they use real cars for some of the shots leading up, then use CGI cars when stuff starts flying around, then they composite in real explosions shot on black, using many layers. In Fury Road, they just did the cars and the explosions in reality and then used CGI to enhance parts of it that didn’t turn out right. ---
**Author:** ![Hampshire](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hampshire/32/4887_2.png) [@Hampshire](https://boards.straightdope.com/u/Hampshire)\ **Post date:** [August 5, 2016, 2:42am UTC](https://boards.straightdope.com/t/spitting-in-supercharger-intake-in-mad-max-fury-road/761616/36 "2016-08-05T02:42:55Z")
> [@Hail\_Ants](#): > > You forgot to mention her CGI robot-arm\*!\* > > In terms of the silliness of the film overall, the main villain looked ridiculous. It looked like they came up with him by having a cosplay contest at Comic-Con and the most enthusiastic/pathetic fanboy kit-bash wank won. The whole movie had this look, over-the-top silliness with not even the remotest thought to practical reality. What was the point of the milking titty-women? Or the water being released from the top of a huge cliff? Freakazoid controlled the water? Ok, but how the hell did he do that?! Where the hell did the water come from? This is the setup/premise of the whole chase scene later, so if we don’t know/care about these things who gives a shit about why they’re being chased?!? This is Storytelling 101 stuff. > > _The Road Warrior_ struck a perfect balance of enough flash while still having function. This _Mad Max_ was like watching a live-action Saturday morning cartoon. It stopped just short of having cars drive off cliffs and not start falling until the driver had realized it (accompanied with xylophone music). > > I gave up completely when the enemy pursuit team included that flatbed truck with the guy playing the flamethrower-guitar. Excuse me?!? No. It’s still supposed to be a post-nuclear wasteland. So just, no. One of the girls in the movie mentioned that the water was pumped up from deep in the ground. Immortan Joe controlled the water therefore controlled the people. He dispensed the water from the cliff just enough for his followers to survive and worship him for it. Symbolic in the way people would reach to the sky asking the gods for rain. The milk ladies were supplying Joe’s war boys with nutrients. His boys were his strength and it was in his best interest to keep them healthy. Flamethrower guitar guy was there to rally the troops. Keep them pumped up during battles. ---
**Author:** ![coremelt](https://avatars.discourse-cdn.com/v4/letter/c/4491bb/32.png) [@coremelt](https://boards.straightdope.com/u/coremelt)\ **Post date:** [August 5, 2016, 2:46am UTC](https://boards.straightdope.com/t/spitting-in-supercharger-intake-in-mad-max-fury-road/761616/37 "2016-08-05T02:46:27Z")
> [@Hampshire](#): > > The milk ladies were supplying Joe’s war boys with nutrients. I got the impression that the milk ladies were for immortan joe to Drink from, because he believed that drinking human breast milk would prolong his life. ---
**Author:** ![Hampshire](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hampshire/32/4887_2.png) [@Hampshire](https://boards.straightdope.com/u/Hampshire)\ **Post date:** [August 5, 2016, 2:50am UTC](https://boards.straightdope.com/t/spitting-in-supercharger-intake-in-mad-max-fury-road/761616/38 "2016-08-05T02:50:56Z")
> [@coremelt](#): > > I got the impression that the milk ladies were for immortan joe to Drink from, because he believed that drinking human breast milk would prolong his life. Could be. Either way I didn’t find their inclusion “pointless”. I thought it clearly showed they were farming a source of nutrients in a wasteland and that Joe controlled that source. ---
**Author:** ![Left\_Hand\_of\_Dorkness](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/left_hand_of_dorkness/32/7156_2.png) [@Left\_Hand\_of\_Dorkness](https://boards.straightdope.com/u/Left_Hand_of_Dorkness)\ **Post date:** [August 5, 2016, 3:42am UTC](https://boards.straightdope.com/t/spitting-in-supercharger-intake-in-mad-max-fury-road/761616/39 "2016-08-05T03:42:45Z")
I love the OP’s question, with its implicit assumption (even half-joking) that Fury Road stands up to technical analysis :). The movie was a crazy drug trip of a cartoon of an action movie, and I loved it for that; it would never occur to me to question whether any of the physics bore more than a coincidental relationship to our universe’s. ---
**Author:** ![Kobal2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kobal2/32/20_2.png) [@Kobal2](https://boards.straightdope.com/u/Kobal2)\ **Post date:** [August 5, 2016, 8:01am UTC](https://boards.straightdope.com/t/spitting-in-supercharger-intake-in-mad-max-fury-road/761616/40 "2016-08-05T08:01:23Z")
> [@Hampshire](#): > > Could be. Either way I didn’t find their inclusion “pointless”. I thought it clearly showed they were farming a source of nutrients in a wasteland and that Joe controlled that source. The problem there is that it’s more wasteful to turn farmed/gathered food into milk for people to drink than it is to just give them the food directly ;). Kind of like the \*Matrix \*idea of using humans as batteries (yes, yes, I know, it’s the studio execs’ stupid fault and the Wachowskis really wanted it to be about distributed computing) : it costs more energy than it produces, because keeping the cows/batteries alive has a large cost of its own (and of course the lactating process itself is hardly optimized either). [Previous page](https://boards.straightdope.com/t/spitting-in-supercharger-intake-in-mad-max-fury-road/761616.md?page=1) [Next page](https://boards.straightdope.com/t/spitting-in-supercharger-intake-in-mad-max-fury-road/761616.md?page=3)