You could suck out burning gas causing your car to light on fire too fag
Luke Collins
>superchargers increase engine displacement
Ian Morris
>Could you decrease engine displacement by running a vacuum instead? No, your point is that you want to reduce the amount of air going in. Using a vacuum wouldn't be very effective. Instead you could just make sure the throttle doesn't open as much so it allows less air in. Most manufacturers already do this with their drive-by-wire systems.
Kevin Brown
This.
Many racing engines run restrictor plates for the same effect.
Grayson Scott
I thought you could do this with the throttle body, but I bet with the crankcase under vacuum it would be very effective.
I figured motors would do something like this already because its so simple.
Effectively, yes, turbos and superchargers do this. So I was wondering about manipulating pressure to decrease displacement. Kinda like how Chevy came up with the idea to shut off cylinders to save fuel in V8s, except a much simpler solution.
You know engines run on explosions and fire, right?
Carson Morgan
you're making so many assumptions that this post is hard to read.
no, you can't decrease engine displacement by running a vacuum. you can run a restrictor plate to limit the amount of air allowed through the throttle body but that would be it.
and the crankcase is typically under a vacuum anyways.
but yeah, all you can do is run a restrictor plate, and even if you had a 'restrictor on demand' system to limit the amount of air, you would have to be specific on when you could use it because people would just push down the gas pedal farther and use more fuel anyways
Eli Murphy
>Could you decrease engine displacement by running a vacuum instead? Yes, it's called closing the throttle. Are you retarded?
Kevin Bell
Turbos and superchargers don't increase engine displacement. Every cycle of the engine displaces the same amount of volume with boost or not. Forced induction increases the volumetric efficiency of that displacement.
Charles Ortiz
I'm not necessarily making assumptions as much as vague statements.
Yes, if you run a crankcase vacuum system and keep it under a strong vacuum and you restrict the airflow the engine will run on a vacuum(running on less than standard atmospheric pressure) meaning that it will basically decrease displacement.
What I'm asking is how far can you take this idea? Can you in simple terms turn a V8 into something that runs more like a V6 or V4? Like having to run at 2k-3k rpm on the highway instead of less than 2k for cruising speed? Trade off RPMs for fuel under certain circumstances.
I think what I'm saying is more complicated than manipulation of the throttle.
Engine displacement is measured in volume. Turbos and superchargers manipulate that volume for power. Technically you're right.
I'm talking about manipulating the volume to achieve fuel efficiency.
Samuel Rivera
>Engine displacement is measured in volume. Turbos and superchargers manipulate that volume for power. Technically you're right.
Forced induction increases air density, not volume
Lucas Rivera
I use volume and displacement as analogies.
I don't know what education level every poster is at so I'm trying to be vague and give everyone a chance to contribute.
Minor technicalities. Surely educated anons understand exactly what I'm saying and less mechanically gifted anons can decipher what I'm saying easily enough.
Luke Carter
>I think what I'm saying is more complicated than manipulation of the throttle. No, it's exactly what you're talking about. Close the throttle, engine draws vacuum, less air goes in, engine makes less power. Intake restrictors are just an easy way (compared to dynoing every car or mandating a spec throttle body) for regulators to functionally cap horsepower.
Dylan Russell
Hell yeah nigger this would work perfect combined with Direct Exhaust Injection. You can decreased displacement by creating vaccuum and also injecting exhaust gas directly. The more you turn up the SC the less gas used and turn up thr SC to max and you actually staret creating new gasoline and refilling your tank. Soon as automotive niggers can get their heads out of their asses they can evolve from hybrid savagery up to in situ vacuum SC gasoline DEI
Austin White
The problem is you are using displacement (volume) interchangeably with pressure or air density. You can't do that. It's very important to be specific in these matters.
Elijah Powell
Pleb you're so stupid, if theres less air then it's less displacement, doesnt matter if the cylinder is smaller or you use a SC to suck the air out it's still equal to less air and less fuel = better fuel economy retard
Lucas Foster
That is only part of it though. I'm also talking about tuning the fuel mixture, keeping the crankcase under a vacuum level normally associated with racing, etc.
So its slightly more complicated.
I've also considered using electric water pumps and electric fans to give the motor a little more horsepower so it can operate better under those conditions.
Lucas Harris
Don't expect it.
If I say "it's at top of the engine" their brains melt because they can't read it unless it says "it's on top of the engine".
Him not realizing volume and density are similar is just that he's dense.
1 liter of air / volume=1 liter
>Example of forced induction managing to push in twice the amount of air into the same cylinder
2 liters of air / volume=1 liter = you now have 2 liter per cylinder efficiently
Jayden Hall
Yes but you understand exactly what I'm saying regardless of terminology.
You're right. I haven't had to talk shop in a very long time so I'm out of practice anyways.
Aaron Johnson
displacement = more air superchargers = more air
obviously the same (^:
Dominic Lopez
Holy shit, I really hope you are trolling. Were you educated in the inner city?
I'm afraid it wouldn't work. You need a certain amount of power to maintain speed. If you have a vacuum to draw air out it will cut power slowing you down and wouldn't increase fuel efficiency. The throttle controls the engine speed by metering air. A vacuum is unnecessary for doing that since it almost cut off all the air to an engine.
Liam Adams
>I'm also talking about tuning the fuel mixture, keeping the crankcase under a vacuum level normally associated with racing, etc. Tuning the fuel system how? Carburetors and FI both operate by controlling air/fuel ratio. Less air means less fuel. Adding more fuel will increase fuel usage and using less fuel will increase combustion temperature and potentially cause detonation.
Go open your hood and take a look at your engine. See the hose that goes from the valve cover to the intake manifold? That's the Positive Crankcase Ventilation (PCV) system. As you draw vacuum from the intake by closing the throttle, a pressure differential is created and high pressure blow-by from the crankcase is drawn into the intake and ran through the engine.
You're talking about a bunch of technologies that have been used literally as long as the ICE has existed.
Mason Murphy
Keeping the crankcase under a hard vacuum would make it cycle easier because the cylinders are breathing a vacuum, though.
Basically, say your feeding a 400ci motor only 300ci of air each cycle and the crankcase is kept under a hard vacuum to assist cycling.
The only thing I'm not sure about is the exhaust, because atmospheric pressure will fight the exhaust system.
Its just for certain circumstances, like to make idling and cruising more fuel efficient.
And yes you need power to maintain speed so an engine like this will have to run at higher RPMs.
I'm asking if you can trade RPMs for fuel efficiency.
Remember, Chevy had a system that shut off cylinders to save fuel. This is idea is meant to achieve those results with much simpler and cheaper modifications.
Yes, these are old technologies. I'm surprised I can't find any info on this, though.
Joseph Thompson
Oh I forgot to remind you I'm talking about keeping the crankcase under racing levels of vacuum, like 8hg or more.
That would make the engine cycle and exhaust easier.
Matthew Davis
>I'm surprised I can't find any info on this, though. You can. Google throttle body, PCV, and AFR.
Xavier Anderson
When you snap the throttle shut, you should have 20-30" Hg of vacuum drawing on the crankcase.
Isaac Peterson
I can't find any info about manipulating and modifying these systems to turn a 400ci motor into basically a 300ci motor, though.
Jace Robinson
Google "3/4 throttle" then?
Joshua Sanchez
And you kill the engines power, too. I'm not trying to suffocate the motor that much.
Nathaniel Cooper
Then how come people don't drive like that?
Nobody wants to drive like an old grandma, I guess?
Keeping a light foot on the pedal is just so simple nobody talks about it much?
Josiah Collins
I don't understand what you're even trying to do. Running a 6L engine with the throttle shut is like running a 50cc engine with the throttle open. If you want something in between, use something in between. Your throttle isn't an on/off switch.
Daniel Johnson
I don't understand either, that's why I'm here.
Gabriel Baker
>Then how come people don't drive like that? They do. I blast past Corvettes and Camaros all day long in my 1.3L shitbox because I have places to be. Any time you don't have the gas pedal on the floor, you're reducing the amount of air your engine can draw.
Easton Diaz
Then why did Chevy bother creating that cylinder shut off system?
I'm going to work. Back in 9 hours.
Kevin Jenkins
Because that limits the engine's potential air draw even further, which means even less fuel consumption.
Hunter Russell
You do know all non-fi cars run with negative pressure correct? Aka a vacuum. How else would air magically rush into the motor unless there was less pressure inside than out.
Evan Martin
>Could you decrease engine displacement by running a vacuum instead? you mean like running the engine with some kind of throttling device? Like a butterfly valve in the inlet tract that could be opened and closed as a variable restriction?
John Collins
I don't think you understand what cylinder deactivation does. It locks the valves closed so that cylinder doesn't draw any air. The idea is to *not* draw a vacuum, because then you're doing the work of moving air that you don't have to.
Lincoln Stewart
Like a valve body to throttle the air going into the engine
A...throttle...body
Aiden Hughes
No. They add pressuried intake air, not displacement. Displacement is physically defined by bore and stroke.
Even if you could reduce the volume of air going in (which you can, using the throttle), you'll still have the same ring drag, same internal friction, same windage, same accessory drive (alternator etc.), and most importantly, you're still combusting it in a suboptimal combustion chamber, not designed for that load.
If you were to put a negative supercahrger on there, it wouldn't get any gains. The supercharger would completely offset any theoretical gains - and there aren't any.
AFR can be easily adjusted for in modern closed loop systems.
Logan Johnson
Restrictor plates have nothing to do with efficiency though, it's just to keep everyone at the same HP level.
Aiden Young
yeah no fucking shit.
Tyler Rogers
Yeah, the reason is different but the effect is the same.
Anthony Reyes
OP, please go learn how in ICE works.
>it will basically decrease displacement. No. Stop being dense, displacement is measured by bore and stroke. Using a throttle does not change these measurements.
>Can you in simple terms turn a V8 into something that runs more like a V6 or V4? Yes, it's called cilinder deactivation. Look it up.
>Like having to run at 2k-3k rpm on the highway instead of less than 2k for cruising speed? You really are dense, aren't you? A gearbox at x MPH in x gear will always make x RPM. Even if you'd swap the engine out, it'd still make the same RPM in x gear at x MPH.
>Trade off RPMs for fuel under certain circumstances. No. Nonononononono. This is stupid. All you'd be getting is increased pumping losses.
>I think what I'm saying is more complicated than manipulation of the throttle. No. It's exactly like manipulating the throttle.
Mason Carter
>I use volume and displacement as analogies. They're utterly wrong analogies.
>I don't know what education level every poster is at so I'm trying to be vague and give everyone a chance to contribute. So you should use proper terms, and not confuse everybody. This is how every scientific discussion works, dumbing down creates confusion.
Cameron Wilson
>400ci motor into basically a 300ci motor THEY
PHYSICALLY
CANNOT
Jesus OP, are ya really this dense? Displacement = bore * stroke * cilinder count. There is no dynamic changing that. By closing the throttle partway, you reduce airflow and therefore fuel consumptiopn. That's it.
>I don't understand either, that's why I'm here. Veeky Forums in a nutshell
Cooper King
>Forced induction increases the volumetric efficiency of that displacement. You mean the manifold pressure?
Aiden Lee
Hakuna miata is that u?
Colton Morgan
Yes, a higher manifold pressure would increase volumetric efficiency. With an N/A engine you rarely exceed 90% VE unless it's a race engine. With forced induction you are forcing air in at higher than atmospheric pressure which means 100%++ VE.
Michael King
Any benefit of having a strong vacuum in the crankcase for the power and intake stroke, which would most likely be negligible and not worth the added cost and complexity, would be mostly negated by the effect on the compression and exhaust stroke.
The throttle already can limit a 400ci motor to 300ci of air of atmospheric air, which will expand to 400 ci but be lower than atmospheric pressure. Strong vacuum from the crankcase wouldn't help draw more air in and would only help draw fuel/air mixture and combustion gases into the crankcase.
Trading RPM for fuel efficiency is a gearing consideration. That's why some manufacturers really like CVTs, they can run a low RPM for any cruising speed you choose.
Easton Rogers
>The throttle already can limit a 400ci motor to 300ci of air of atmospheric air Stop saying this stupidity.
Cooper Sullivan
MILLER CYCLE
Bentley Butler
Holy shit you're fucking super stupid
Jeremiah Long
Creating a vacuum a.k.a. closing the throttle.
John Fisher
Christ, you are stupid.
It's PV=nRT, BASIC BITCH PHYSICS.
I bet flipping burgers is beyond a mental acuity.
Brandon Ortiz
>++ what did he mean by this?
Easton Moore
>Strong vacuum from the crankcase wouldn't help draw more air in and would only help draw fuel/air mixture and combustion gases into the crankcase.
I'm going to disagree you you there. You're effectively increasing the pressure differential between the outside of the engine (atmosphere) and the inside (crankcase). The result will be more airflow.
There are other benefits too, such as reduced crank windage (cleaver crank scrapers will also reduce windage losses), better ring sealing (which allows the use of lighter ring packs reducing friction), and reduced pumping losses in the crankcase.
U R Retard
Carson Clark
Too bad manifold pressure doesn't stay constant in a properly designed n/a engine. Do you even have a mechanical engineering degree?
Owen Lopez
>Too bad manifold pressure doesn't stay constant in a properly designed n/a engine by properly designed you mean one fitted with a throttle body?
Jordan Lewis
No, by utilising resonance and port flow to create a low pressure zone inside the chamber, even before the intake stroke begins.
Leo Allen
I'm sure he, just like everyone else in thread (except OP) knows this. What's your point.
Levi Jones
wow man, you seem like a real expert. why don't you share more of your wisdom with us plebs?
Justin Stewart
I meant well beyond 100% VE. More air, the higher % VE
I'd be interested to see any what would happen with a negative pressure crankcase in regards to crank windage and pumping losses. I don't think it would make much of a difference. While the pressure differential would help draw the piston down on intake, that same difference would resist on the compression stroke which would make it internal energy on the crank.
>Too bad manifold pressure doesn't stay constant in a properly designed n/a engine
No shit, dullard. We're not arguing flow, were talking about static scenarios to argue efficiency. Do you have a high school diploma? It sounds like you read a few articles on thermodynamics or fluid dynamics and think you're hot shit. Stop while you are ahead.
Jordan Ross
>that same difference would resist on the compression stroke which would make it internal energy on the crank. Unless you compartmentalised the crankcase so the air is compressed by the piston descending, then expands as it rises. There are going to be losses of course, you can't escape that.
And you're right. The benefit will be in the region of a few %, and mostly at 100% throttle. Great for full race engines, not really great for road cars that spend 99% of their time at part throttle.
Anthony Hill
If you're thinking about a supercharger running in reverse creating a vacuum in the intake manifold instead of pressurizing it, that won't work. If the intake is at a lower pressure than the cylinder, then the air won't flow into the cylinder and the car won't run.
If there's strong enough negative pressure above the piston it would draw oil up from the sump and into the combustion chamber increasing emissions, getting gunk all over the valves, and causing excessive amounts of oil consumption.
A motor simply can't run with a vacuum in the intake. You could limit the amount of air going into the engine to increase efficiency though. Which is what a throttle body does...
Carter Brooks
Shows what you know retard, I'm talking about creating a vacuum on the exhaust side like a reverse supercharger
Gavin Howard
2/10
Christian Russell
I said less air = less displacement and less fuel what's wrong about that? You're a retard displacement is only relative to the pressure of the atmosphere if you create a vacuum then you effectively lower the displsacement >dumb plebs lrn to physics
Joshua Hill
>this guy thinks engines are elastic
Jacob Price
Engines are not elastic, only the air that goes inside of them dumbass
Carter Baker
It's internal combustion, not external combustion. The inside of an engine is much more capable of handling explosions and fire than the outside - especially modern ones with plastic intakes and injectors
Oliver Rivera
>Could you decrease engine displacement by running a vacuum instead?
Various GM cars already have variable cylinder loading. At highway cruising speed with cruise control on, the load on the engine is quite reduced (no more drastic acceleration) and so the engine may turn off half the cylinders. This improves fuel economy of course. And no, it does use different cylinders to even out the wear. Computers just weren't available back in the carburetor era.
Owen Sullivan
I remember that, it was called chuggling and misfiring.
Charles Hernandez
Yes, and displacement is volume, and the volume contained within a cylinder is always the same, but it's the ammount of oxygen that increases inside of that volume of air.
Also, to answer OP's question, you can always get a hot air intake which sucks warm (therefore less dense) air into the engine. A vacuum would be fucking retarded as it directly affects engine displacement (actually removing a certain volume of air from the cylinder rather than making the air less concentrated)
Carter Mitchell
yes, obviously. cars already have cylinder deactivation and overdrive so they're efficient enough for the time being. -Elon Musk.
Angel Watson
>A vacuum would be fucking retarded as it directly affects engine displacement (actually removing a certain volume of air from the cylinder rather than making the air less concentrated) You were correct up until this point. You're just sucking air out of a container. You haven't changed the size of the container.
Blake Foster
that's literally what a throttle butterfly valve does user. you can also do it by changing valve opening like valvematic and valvetronic.
Matthew Flores
"Active Fuel Management (formerly known as displacement on demand (DoD)) is a trademarked name for the automobile variable displacement technology from General Motors. It allows a V6 or V8 engine to "turn off" half of the cylinders under light-load conditions to improve fuel economy. Estimated performance on EPA tests show a 5.5%-7.5% improvement in fuel economy."
A bunch of you talked about vacuum. GM indicated "a so-called "pumping loss" causes extra work for the engine to do under partial load conditions because the pistons have to work harder to suck in the fuel-air mixture when the throttle position results in low intake-manifold pressure. Under this scenario, deactivating some of the cylinders allows the remaining active ones to have less manifold vacuum to overcome during the intake stroke."
Other companies have different patented schemes for implementing variable displacement. Honda uses Variable Cylinder Management (VCM). Chrysler has Multi-Displacement System (MDS). Daimler AG has Active Cylinder Control (ACC).
The most drastic is Chevrolet Malibu with its 100% cylinder displacement reduction (aka Stop-Start). When no motion is needed, all the cylinders are stopped (engine stop).
GM is working to implement a revolutionary new software-based system named "Dynamic Skip Fire" to debut in 2020 which will vary displacement for ALL the cylinders in the engine.
A V8-powered SUV typically only requires 30 hp to cruise on a highway to hold its speed and, with DSF, six cylinders shut down to provide a monumental 21-percent increase in fuel economy, as tested in the real world on a GMC Yukon Denali.
Julian Clark
Creating a huge vacuum in the cylinder would just result in increased oil consumption. It would be like having sustained engine braking going on all the time in the cylinders that were having the vacuum.
Isaiah King
superchargers will make you a slow, stupid cuckold
Blake Watson
>b-b-b-but muh dumb boomer memes
Adrian Murphy
OP here, I'm back. Thread went to shit and I'm considering abandoning it.
Camden King
>Judging a super charger on horsepower and not torque
Henry Wright
>not giving the rpm at which the figures are attained >ignoring that what matters is the fucking entire curve and numbers are just part of the story.
This thread is full of cancer.
William Scott
OP here.
I heard it takes a lot of fuel to start a motor spinning.... So a 100% cylinder deactivation makes no sense.
But I guess computers and a modified transmission would allow much less loss.
I guess I'm talking about optimizing a motor to run on no more than 3/4ths of its normal specs. I guess you'd accelerate like a grandma but so long as you merge fine no problematical things would happen
Matthew Miller
Nobody is going to spoonfeed you, retard. Go to a fucking library.
Jack Watson
OP here, this was my fault.
Anons are correct in saying displacement is unchangeable by current definition without piston/rod/chamber modifications.
Atmosphere is flexible.
I'm asking if instead of cylinder deactivation, can you modify pressures and fuel/air ratios inside the motor to achieve the same results as deactivating cylinders?
That's IT
Chase Martin
Sorry, a bit of an overreaction.
Mason Perry
Its OK, man.
I guess I want to be able to flip a switch on a big motor vehicle that forces me to drive like a granny but still merges into highways safely, then I flip the switch again if I need to tow something.
Jaxon Campbell
>I heard it takes a lot of fuel to start a motor spinning.... So a 100% cylinder deactivation makes no sense.
The beauty of direct injection engines is that they spool up right away compared to a throttle body or carbureted engine. The re-start inertia comes from the battery and that is why the Bu has two batteries (one in front, one in the trunk). While the engine is stopped there is still power brake and power steering available since the car is drive by wire except the physical links with the steering wheel and brakes are still there as backup.
The start-stop system comes from Europe where it seems to not have killed the engines with wear and tear from all that starting and stopping. The driver can control it by not pushing all the way down on the brake pedal as he slows to a stop. If the driver anticipates a long wait at the light or traffic jam, he can push the pedal all the way down and the engine stops.
GM is desperate to find ways to get more mileage for the Malibu. The 2016 Limited seems to be the last of the normally aspirated higher-horsepower Bu (2.5 liter 197 HP) since the others use smaller engines with turbos to force more horsepower out of them. I don't like the idea of start-stop used on turbo engines due to the much greater number of cycles of turbo heat soaking of the oil. I guess those people should use full synthetic oil.
.
>...if you create a vacuum then you effectively lower the displsacement There is no desire to create a really strong vacuum in the cylinder because that creates the situation of engine braking. In effect, that cylinder fights the others that are supplying energy.
Your idea is virtual displacement. GM is implementing Dynamic Skip Fire in 2020 as a step on the path achieving virtual displacement changes. FCA lacks research money. Ford lacks research enthusiasm. So it's up to GM to spend a ton of money to invent virtual displacement change.
Then the Chinese will just copy it for free
Adam Green
If you use a supercharger on the exhaust side then the engine can propel using vacuum instead of using gas to go boom then you can just turn the SC up or down to create more vacuum the suck on the piston
Nathan Rogers
>turbo makes more torque and power on every portion of the redline
Benjamin Campbell
>There is no desire to create a really strong vacuum in the cylinder because that creates the situation of engine braking. In effect, that cylinder fights the others that are supplying energy.
op here.That's why I want to think of a system that distributes the load and wear across the entire motor. Shutting off cylinders creates uneven stress on the crank.
The only solution I see is reducing the volume of sir entering the motor.
Jayden Scott
OP here again. No matter how much vacuum is in the crankcase it won't suck a single piston down. The crankshaft and pistons are very balanced.
The bottom end of a motor would have to have a complex bolt on like a header with its own "throttle" capable of individual piston effect.
While this may well end up being the future for conventionally fueled engines I'm looking for other things.
Another header on the bottom of the motor, where the oil pan would be.... But instead of fuel injectors it has vacuum drivers?
That's more complicated than I hoped but it could evolve from an idea into a bolt on with an excessory powered by battery or belt. Literally a reverse supercharger
Angel Gutierrez
Maybe "vacuum directors" instead of vacuum drivers.. Lol
Just a fuel injector that pulls material in rather than push it out
The future is here!!!
Nathan Price
I constantly mentioned crankcase vacuum tomake it easier for pistons to cycle in a motor aspirating on less than 1 atmosphere btw
Jaxson Peterson
I have too, because the motor needs to exhaust into a full atmosphere
Evan Russell
Oh god I started talking to myself
Connor Morris
Are you dumb as fuck? Do you know how a diesel works?