34
votes
Accepted
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 ...
- 153k
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 ...
- 23.5k
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 ...
- 33k
11
votes
Accepted
Why is the effect of a bad fuel pump more noticable at higher speeds?
Background
You asked
Why is the effect of a bad fuel pump more noticeable at higher speeds?
I assume that by 'higher speeds' you mean engine speeds or RPM's.
During high RPM operation an ICE ...
- 33k
11
votes
Accepted
How exactly does running fuel-lean increase the temperature of ignition?
You have a qualitative description of what happens, but let's break it down to a smaller scale. When we talk about "temperature" of something, we are really talking about how fast the molecules are ...
- 273
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 ...
- 805
10
votes
Difference between fuel pressure and fuel rail pressure
On a car with fuel injection there can be two fuel pumps, one high-pressure and one low-pressure. The low-pressure pump moves the gas from the tank up to the high pressure pump. The high pressure ...
- 895
9
votes
Accepted
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, ...
- 153k
9
votes
Accepted
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 ...
- 3,343
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 ...
- 11.6k
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 ...
- 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 ...
- 28.7k
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 ...
- 153k
7
votes
How exactly does running fuel-lean increase the temperature of ignition?
Funny you should ask this Max :)
First lets make sure of our definition. Running an engine lean means changing the air / fuel ratio to have more air than is ideal (14.7:1 air to fuel).
In my reading ...
- 9,326
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 ...
- 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 ...
- 12.2k
6
votes
Accepted
Fuel system question
That pipe probably goes to the tank too, it is just there to let air out of the tank while adding fuel down the main pipe. I believe that your additive will be in the fuel.
- 24.9k
6
votes
Why is the effect of a bad fuel pump more noticable at higher speeds?
It's a demand vs supply deal
The fuel pumps found in most OEM fuel delivery setups today are driven by an electric motor that is running at a fixed speed. This effectively fixes the flow rate ...
- 39.1k
6
votes
Accepted
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 ...
- 39.1k
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 ...
- 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 ...
- 39.1k
6
votes
Accepted
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)
...
- 1,722
6
votes
Accepted
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 ...
- 12.1k
5
votes
How exactly does running fuel-lean increase the temperature of ignition?
If you have ever seen an oxy-acetylene torch being used, you will have noticed that before the oxygen is turned on, the torch has a bright yellow flame. This is the fuel burning in a less than ideal ...
- 24.9k
5
votes
2001 Infiniti QX4 rough idle - leaking fuel damper vacuum port
Thanks for the great detail. Considering this is a bit of an odd issue, I'll try thinking outside the box a little. But first I would use a multimeter to test the coolant temp sensor, then o2 ...
- 898
5
votes
Strong vibrations when idling even after replacing engine mounts (automatic transmission)
I've had this problem with my Honda accord 96 for an entire year and just figured out what was causing the vibration in idle mode. Changed mounts, cleaned air idle control valve and throttle body . ...
- 51
5
votes
Accepted
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:
...
- 39.1k
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, ...
- 7,047
5
votes
Accepted
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 ...
- 76
4
votes
Calculate amount of fuel injected
You can do this through the OBD-II protocol (SAE J1979).:
+------+-----+-------------------+
| Mode | PID | Description |
+------+-----+-------------------+
| 01 | 5E | Engine fuel rate | (...
- 39.1k
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