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34 votes
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We have fuel injection, why not air injection?

Simple reason: volume. @ 14.7:1 stoich, your input into the cylinder would need to be 14.7x bigger (or push that much more) through a nozzle than you would the fluid which is fuel. You state it would ...
Pᴀᴜʟsᴛᴇʀ2's user avatar
26 votes

We have fuel injection, why not air injection?

You have almost but not quite described the operation of either a Turbocharger or Supercharger. The idea of the air under pressure being injected from a common fuel rail would likely not work as it ...
Steve Matthews's user avatar
16 votes

We have fuel injection, why not air injection?

In many ways, you're describing a 5 stroke engine 5 Stroke engines are using a piston to provide a secondary means of compression for the AFR. Although, not injecting air they are compressing the ...
DucatiKiller's user avatar
  • 32.9k
11 votes

We have fuel injection, why not air injection?

High pressure gas is very difficult to create, much harder than high pressure liquid. It's because liquids are not compressible, so you can squirt them virtually as hard as you want, while gas will ...
Agent_L's user avatar
  • 815
9 votes
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How can vehicles run on E?

The gas gauge is just an indicator and each vehicle is going to be different. I know the older Datsun Z cars had two gas gauges, one was the main one which showed the volume of gas down to 1/4 tank, ...
Pᴀᴜʟsᴛᴇʀ2's user avatar
9 votes

Direct Injection Injectors - How do they prevent blow back into the fuel system?

In cylinder pressure is in the 200 psi range. GDI fuel pressure is varied from 500 up to around 3000 psi. This alone is enough to keep fuel blow-back to a minimum. Carefully engineered injector pintle ...
Fred Wilson's user avatar
  • 11.6k
9 votes
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Direct Injection Injectors - How do they prevent blow back into the fuel system?

I will try to answer this as best as possible. There are a few factors that come into play here (Mainly the manufacturer of said engine). Direct injection petrol engines work much like a diesel. You ...
cloudnyn3's user avatar
  • 3,343
9 votes

We have fuel injection, why not air injection?

Here's a variation that I've thought about at great lengths. Even doing some of the preliminary math. IC engines don't need air. They need oxygen. So... eliminate the valvetrain entirely, and have ...
SteveRacer's user avatar
  • 12.4k
9 votes

Best way to repair a rotten fuel line?

To be honest, if part of the fuel line is rotten, I'd be tempted to replace the whole line - chances are the rest isn't far behind... Modern rubber hoses should last a decent amount of time, they're ...
Nick C's user avatar
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8 votes
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Thinking of running E85 to clean my Corvette valves, pistons and heads

There are several issues with what you are planning to do. If you haven't done so already, please read this answer I wrote about using E85 instead of non-E or E10 fuel. While ethanol fuels do clean ...
Pᴀᴜʟsᴛᴇʀ2's user avatar
7 votes

Why isn't injection managed to use the entire intake stroke?

Keep in mind that at high loads/WOT, the injector may be open nearly constantly - during all four strokes. (Injector Duty Cycle >90%) In fact, many systems switch from sequential port to bank and ...
SteveRacer's user avatar
  • 12.4k
7 votes

What actually affects engine compression ratios?

Put simply, an engine's compression ratio is the ratio between the volume of a cylinder with the piston at the down position (position 1 and 4 in the pic below) and the volume of the same cylinder ...
tlhIngan's user avatar
  • 12.2k
6 votes
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How to determine injector size for custom engine?

Assuming this is for a naturally-aspirated application, your calculations are reasonable. I think you just missed dividing the value obtained by the number of cylinders. Usually 2.5 L engines have ...
Zaid's user avatar
  • 39.2k
6 votes

Best way to repair a rotten fuel line?

I've had to deal with rotten fuel lines on my '94 Nissan. Took me a year to find a suitable solution. Like you, I was considering steel lines to replace the entire thing, but the steel lines I found ...
tlhIngan's user avatar
  • 12.2k
6 votes

Why isn't injection managed to use the entire intake stroke?

Consequently, you get a superrich part of mixture together with just air in the cylinder. These still have to mix/homogenize in the cylinder to get a good combustion. This is already handled by both ...
Zaid's user avatar
  • 39.2k
6 votes
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Why Ride by wire when the fuel injector is there

The difference between FI and Ride by Wire Fuel injection means that the flow of fuel to the engine is controlled by the ECU, as opposed to a carburetor. (of course, there's more to it than that) ...
justinm410's user avatar
  • 1,732
6 votes
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Why does the fuel pump buzzing sound go away after a couple of seconds?

Most fuel systems have a pressure-switch. So when the power is first applied the fuel system is unpressurized. The fuel pump is then turned on to build up pressure so the engine can start. Once the ...
jwh20's user avatar
  • 12.1k
5 votes
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1998 V6 Mustang -20+ LTFT on both banks

Cleaning the MAF won't help here because the fuel trims are negative. A dirty MAF would typically under-read mass air flow and subsequently force a positive fuel trim correction. A few possibilities: ...
Zaid's user avatar
  • 39.2k
5 votes

Is Tom Ogle's 100+mpg engine actually feasible?

Looking at the market, VW has built the VW XL1 (EN, DE), a hybrid car with up to 260mpg. The german site says there was a test drive on the street where the car indeed consumed 0.89l diesel /100km, ...
sweber's user avatar
  • 7,057
5 votes
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Toyota Yaris Fuel Saving

Back in the day cars needed to be shifted closer to there optimum torque to avoid lugging the engine. Higher rpm's would be beneficial in this case. Your car is new enough it simply retards the ...
cerial's user avatar
  • 76
4 votes
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Is it OK to run a diesel engine with a blocked fuel injector return line?

tl dr: Could you? Probably. Should you? No. Engines with a return line need to have it intact or you will be creating over pressure on the entire fuel system. This would cause you to dump more fuel ...
Pᴀᴜʟsᴛᴇʀ2's user avatar
4 votes
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Is the after catalyst oxygen sensor used for engine mixture control?

The rear fuel control controversy has been the subject of some interest on professional automotive repair forums in years past, principally i-ATN. Rear fuel control strategies are used extensively; ...
Fred Wilson's user avatar
  • 11.6k
4 votes
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Slightly low MPG - need help with my checklist

Sounds high for a car with a 2.0 liter engine. I used to have 1989 Opel Vectra with 2.0 8V SOHC engine, and the consumption was around 8-9L/100km. But then again, if you drive mainly short trips in ...
juhist's user avatar
  • 14.6k
4 votes
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What actually affects engine compression ratios?

I always assumed that the less "square" (or more "undersquare") a motorcycle engine was, the higher the compression ratios it can have. In order to maintain the same in-cylinder displacement a ...
Zaid's user avatar
  • 39.2k
3 votes

We have fuel injection, why not air injection?

I think the concept would be like taking a piston compressor to pump air into a piston engine, so energy to pump the air compressor pistons would counter the energy developed by the engine pistons. ...
spicetraders's user avatar
  • 1,533
3 votes

Is it OK to run a diesel engine with a blocked fuel injector return line?

You don't say the specific engine in your car but assuming it's one of the 1.9 TDI's, I'd say it's definitely a bad idea to run with the fuel return "to air" or blocked. I have a 2003 Bora (Jetta IV) ...
Steve Matthews's user avatar
3 votes

Advantages of direct vs sequential fuel injection

Gasoline direct injection can improve both fuel efficiency and power in an engine. Port fuel injection engines need to run near stoichiometric fuel/air mixtures (slightly lean is possible), in part ...
Rob's user avatar
  • 31
3 votes
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Starting fluid, does it require a spark or autoignite?

If the engine is cold, there is no way the combustion chamber is going to get up to 160 degrees C. even when the air is compressed. So your problem is with the fuel system; either the fuel pump, or ...
Mark Stewart's user avatar
3 votes

1999 Subaru Forester - bad acceleration, rough shifting

I'm leaning towards the throttle position sensor being out of adjustment/bad or a bad mass airflow sensor. Perform a volumetric efficiency test, record your IAT in °F, RPM and MAF in g/s. Use an ...
Ben's user avatar
  • 10.7k
3 votes

Percent of Air and Fuel used for Combustion

Upto to which point this air can be reduced. (I mean in the AFR ratio like 10: 1 , 8: 1) ? Realize, if you were to open the butterflies and nothing else were to occur (no additional fuel), you'd ...
Pᴀᴜʟsᴛᴇʀ2's user avatar

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