I'd like to see BF1 on that graph to compare with a real racing gas consumption.

edit:
well, we don't have 100% full gas oval in a real F1, so there is no sense to compare.

Yaamboo "this is how it was explained during our truck driving courses in the Army"

You can't compare to a diesel because they do not run at a constant fuel to air ratio like gasoline engines do. Gasoline engines must have a fuel to air ratio close to 14.7 to 1 all of the time from idle to full out.

Quote from jimimonet :

Yaamboo "this is how it was explained during our truck driving courses in the Army"

You can't compare to a diesel because they do not run at a constant fuel to air ratio like gasoline engines do. Gasoline engines must have a fuel to air ratio close to 14.7 to 1 all of the time from idle to full out.

Gasoline cars without catalytic converter can range for example from 17:1 to 11:1 (some carbed rubbish go even richer), depends from throttle position (in sense of engine load, how you use engine).

Gasoline engines with catalytic converter don't like rich mixture, but in short term usage, like in warmup phase they do run richer and if you are cruising they can use leaner mixture, some japanese manufacturers have made engines that can run leaner mixture than stoich even when you accelerate, direct injection is particularly handy in this kind of engines.

I would say that what you say is rather wrong or at least you did express it bit unclear manner

a turbo boost more air/fuel mixture in the cylinders.
a 1000cc car can than perform like ,lets say, a 1500 cc car (well in the '80 this kind of calculation was used to have a "fair" race between cars with and without turbo in Holland:really

Quote from JTbo :

Gasoline cars without catalytic converter can range for example from 17:1 to 11:1 (some carbed rubbish go even richer), depends from throttle position (in sense of engine load, how you use engine).

Gasoline engines with catalytic converter don't like rich mixture, but in short term usage, like in warmup phase they do run richer and if you are cruising they can use leaner mixture, some japanese manufacturers have made engines that can run leaner mixture than stoich even when you accelerate, direct injection is particularly handy in this kind of engines.

I would say that what you say is rather wrong or at least you did express it bit unclear manner

Yeah, but when the only change is addition of turbo, your mixture will stay the same as that without a turbo, so I don't see how turbo would give you better gas mileage at cruise.

Turbo does give you better gas mileage when compared to NA motor of the same horsepower, because when you're not spooling, you're taking advantage of the smaller displacement.

Quote from wheel4hummer :

If you are cruising at 60mph, then you are not making any boost. Unless you are driving a huge truck.

That's not neccesarily true. Different cars are set up with different sized turbos. A small sized turbo will peak at 2000-3000 rpm, whereas a large turbo may not peak until 5000-6000 rpm. You'll find that speed does not matter at all (apart from the air-intake in engines) but it is the rpm that matters.

Small turbos are used in most road-going non-sporting cars because they spend most of their time in the low rpm and so that they get better mileage. Large turbos are used in racing cars because they spend all of their time in the rpm range.

Then, it depends what gear you are in. So, a road-going car (xrg, xrt) in 5th gear cruising at 60mph will be running at around 3,000 rpm, which means that it would be using the full turbo boost available to it. Ask any car expert, and you'll find that my turbo knowledge is correct (even though it's simplified!).

Try doing a test with xrg and xrt both running at 3,500 rpm and with the same amount of petrol and you'll find that the xrg will probably run out first (I say probably because I haven't done this myself and I'm not sure how accurately LFS would portray this real life scenario).

of course not just more air goes into the engine,more fuel too,so mixture changes too,so make sure u change the air mass meter too

Yes, but as was mentioned before (i think), adding only more oxygen will increse performance. Example 1 - Removing the air filter on a car will let more oxygen in (one of the first steps in preparing race machines), but the engine does not automatically bring in more petrol. Example 2 - Nitrous Oxide (NO2) is pumped into racing engines because of its high oxygen content, but more petrol is not used.

So, putting in more oxygen will NOT make the engine increse petrol intake.

Quote from dougie-lampkin :

A small sized turbo will peak at 2000-3000 rpm, whereas a large turbo may not peak until 5000-6000 rpm.

That is not always true.... Boost mostly depends on the load on the engine. That's why turbos don't make any boost when you decelerate. (Except for jake-braking trucks, I think)

Quote from wheel4hummer :

That is not always true.... Boost mostly depends on the load on the engine. That's why turbos don't make any boost when you decelerate. (Except for jake-braking trucks, I think)

No, it doesn't (well not in standard turbos anyway). Turbos come in different sizes (the actual "turbine" inside the turbo that is spun) so a small turbo will spin quickly when a small amount of waste gas comes through the exhaust and power the compressor forcing more air into the engine. However, if you have a large turbo, passing a small amount of waste gas through the exhaust will have very little effect on it.

Since a turbocharger increases the specific horsepower output of an engine, the engine will also produce increased amounts of waste heat. This can sometimes be a problem when fitting a turbocharger to a car that was not designed to cope with high heat loads. However, the higher compression ratios attained generally contribute to greater fuel efficiency.
It is another form of cooling that has the largest impact on fuel efficiency: charge cooling. Even with the benefits of intercooling, the total compression in the combustion chamber is greater than that in a naturally-aspirated engine. To avoid knock while still extracting maximum power from the engine, it is common practice to introduce extra fuel into the charge for the sole purpose of cooling. While this seems counterintuitive, this fuel is not burned. Instead, it absorbs and carries away heat when it changes phase from liquid mist to gas vapor. Also, because it is more dense than the other inert substance in the combustion chamber, nitrogen, it has a higher specific heat and more heat capacitance. It "holds" this heat until it is released in the exhaust stream, preventing destructive knock. This thermodynamic property allows manufacturers to achieve good power output with common pump fuel at the expense of fuel economy and emissions. The stoichiometric Air-to-Fuel ratio (A/F) for combustion of gasoline is 14.7:1. A common A/F in a turbocharged engine while under full design boost is approximately 12:1. Richer mixtures are sometimes run when the design of the system has flaws in it such as a catalytic converter which has limited endurance of high exhaust temperatures or the engine has a compression ratio that is too high for efficient operation with the fuel given.
Lastly, the efficiency of the turbocharger itself can have an impact on fuel efficiency. Using a small turbocharger will give quick response and low lag at low to mid RPMs, but can choke the engine on the exhaust side and generate huge amounts of pumping-related heat on the intake side as RPMs rise. A large turbocharger will be very efficient at high RPMs, but is not a realistic application for a street driven automobile. Variable vane and ball bearing technologies can make a turbo more efficient across a wider operating range, however, other problems have prevented this technology from appearing in more road cars . Currently, the Porsche 911 (997) Turbo is the only gasoline car in production with this kind of turbocharger, although in Europe turbos of this type are rapidly becoming standard-fitment on turbodiesel cars, vans and other commercial vehicles, because they can greatly enhance the diesel engine's characteristic low-speed torque. One way to take advantage of the different operating regimes of the two types of supercharger is sequential turbocharging, which uses a small turbocharger at low RPMs and a larger one at high RPMs.
The engine management systems of most modern vehicles can control boost and fuel delivery according to charge temperature, fuel quality, and altitude, among other factors. Some systems are more sophisticated and aim to deliver fuel even more precisely based on combustion quality. For example, the Trionic-7 system from Saab Automobile provides immediate feedback on the combustion while it is occurring by using the spark plug to measure the cylinder pressure via the ionization voltage over the spark plug gap.
The new 2.0L TFSI turbo engine from Volkswagen/Audi incorporates lean burn and direct injection technology to conserve fuel under low load conditions. It is a very complex system that involves many moving parts and sensors in order to manage airflow characteristics inside the chamber itself, allowing it to use a stratified charge with excellent atomization. The direct injection also has a tremendous charge cooling effect enabling engines to use higher compression ratios and boost pressures than a typical port-injection turbo engine.

That is an overly-complex of the fuel-saving charcacteristics of a turbo

Quote from Voytech :

Example 2:
All NOS setups these day are what's called a "wet" shot. It means that N02 is sprayed into the intake with a additional amount of fuel sprayed as well. I know this as I have a direct port, wet shot nitrous system on my car. Again, without the extra fuel to compensate for extra oxygen, you'd blow the engine.

But I thought you said the ECU compensates for extra air if you were to take the air filter off. Can't you just get a bigger fuel pump instead of injecting extra fuel into the intake with nitrous? Also, what do you mean by "you'd blow the engine"? Engines don't just stop working, something specifically has to malfunction.

Quote from dougie-lampkin :

Turbos come in different sizes (the actual "turbine" inside the turbo that is spun) so a small turbo will spin quickly when a small amount of waste gas comes through the exhaust and power the compressor forcing more air into the engine. However, if you have a large turbo, passing a small amount of waste gas through the exhaust will have very little effect on it.

Absolutely correct, but RPM isn't what causes more exhaust gas! The higher the load on the engine, the more fuel it is burning, and therefore the more exhaust is flowing, which spins the turbo more. There is more exhaust flowing when you floor it at 1500RPM then there is if you are cruising along at 3000RPM.

Quote from wheel4hummer :

Absolutely correct, but RPM isn't what causes more exhaust gas! The higher the load on the engine, the more fuel it is burning, and therefore the more exhaust is flowing, which spins the turbo more. There is more exhaust flowing when you floor it at 1500RPM then there is if you are cruising along at 3000RPM.

But if you floor it, RPM increases! More exhaust gases are caused by burning more petrol and air (lets call it fuel). By burning more fuel, RPM increases as the speed of combustion rises. By having a bigger explosion in the chamber, the piston moves quicker (unless it is under EXTREME pressure, e.g., clutch out handbrake on, but you'd need like a 2.5td to not stall in this case) and so turns the camshaft quicker, which RPM is read off, isn't it? I'm not too sure where RPM is read off of (Gimme a break, I'm only 15!) but it must be before the clutch so when the piston accelerates, RPM increases. Jeez, I'm getting so lost in this!

Quote from Voytech :

You are so worng that I don't even know where to start...

Ok. Example 1:
Modern cars that don't use carburetors, have a computer chip that checks the A/F ratio and depending on the load and other factors (like temperature of the air) will add the right amount of fuel. So, when you take off the air filter/box, it will compensate for more air by adding more fuel. If it didn't, the engine would run LEAN (not enough fuel, causing premature detonation (often referred to as PINGING).

Example 2:
All NOS setups these day are what's called a "wet" shot. It means that N02 is sprayed into the intake with a additional amount of fuel sprayed as well. I know this as I have a direct port, wet shot nitrous system on my car. Again, without the extra fuel to compensate for extra oxygen, you'd blow the engine.

I sincerely hope you understand this.

Sorry didnt see your post! I do understand this, but not ALL cars have these modern set-ups. In example 1, a car burning more oxygen would not blow up (normal ratio is , 14.7:1 (optimal), but a car could run well up to 18:1). In older cars (before ECU's), if you ran it up to very high speeds (think of old porsche 911) more air would be forced into the chamber (oxygen is a 21% constituient of air), but more fuel would NOT be added. So, according to you, old cars could not be driven fast enough to allow more oxygen than 14.7:1 or else the car would blow up? AFAIK, fuel injection pumps with carbs are in use in racing cars up to today, and on high-powered motorbikes, as ECU's aren't really very effective at 12,000 RPM (think of the response time needed when the camshaft revolves 200 times a second - That's once every .005 seconds. What kind of ECU can update at that speed over the course of a race?)

Dear God, I just realised that this discussion came out of some guy testing fuel economys of LFS cars! God this conversation has progressed! lol

You are still wrong... You said that boost is proportional to RPM!

wow, the FZ is as worst as a Hummer.

Inventing a wheel is rather pointless when there already is instructions how to make a wheel

Quote from dougie-lampkin :

I'm not too sure where RPM is read off of

It's read from the crankshaft position sensor.

LOL this thread has caused a lot of stupid posts from people....

I could talk all day about the physics of gasoline motors.

Let me put it this way. Lets forget about the results from my experiment for a minute.

Caution: THIS IS A GENERALITY... ok keep reading

Take a stock Naturally aspirated gasoline engine, lets say a 3.0L v6 that gets about 25miles to the gallon on the highway. If you put a turbocharger on the car (including all the nessesary hardware... Intercooler with piping, and assuming you use stock exhaust manifolds, and the motor is kept stock) the car will get better highway MPG (cruising) almost indefinetly. Why? To make a very long and complicated explaination very short, you are increasing the volumetric efficiency of the engine by introducing a turbocharger or supercharger. Theres just no other simple way to explain it.

OK. Before you kiddies have an ADD attack... keep reading (and again, im being very basic here).

Q: But a turbo doesnt spin very much if you are not in boost.
A: You're dumb. A turbo CONSTANTLY spins as soon as you start your engine. What happens when a turbo spins? It increases the flow of air into your engine. And what does that mean? Better volumetric efficiency. Why do you think theres a saying "the power is in the cylinder heads"?. Because its true. Its how WELL your car flows air that influences EVERYTHING. I would have to start talking about the physics of fluids and the physics of combustion for alot of you to understand, and i just dont want to do that.

Blah blah i really dont want to get in to this too much, its a beaten dead horse conversation thats been talked about OVER and OVER and OVER again.

There are so many ways to increase the fuel efficiency of a gasoline engine. You guys want to read about some interesting techniques? Check out these following links.

http://www.somender-singh.com/
http://www.popsci.com/popsci/f ... 1000004eecbccdrcrd/3.html Popular science article.
http://www.mpgresearch.com/index.php

Oh, BTW.... dougie... dont rely on wikipedia anymore. That crap you copied and pasted from wikipedia isnt even totally accurate. The kid that made that wiki is no more knowledgeable that alot of the people on this forum.

Wheel4hummer is correct. More load=more exhaust. In a turbo application, you want to load the car in order to build boost more quickly.

However, more rpm with load= more exhaust overall. So say you are seeing 50% load at 1000rpms, then compare it to 50% load at 3000rpms.... More exhaust will be created at the 3000rpm mark. And you can test it yourself. Another way to look at it... at 3000rpms, apply 50% tps and see how fast the turbo spools. Then do the same thing but apply 100%TPS. vwahla.

Why do you think they offer higher stall torque converters for automatic cars? Not just because you can launch the car closer to or at its peak torque range. In turbo cars it helps because you are able to load the car while increasing the rpm at the same time, enabling you to build boost a lot easier. Theres also a reason why companies that sell turbos also give a specific torque converter specification for that size turbo. The larger the turbo, the larger the converter you are going to need to spool that turbo efficiently and effectively.

My fingers hurt...

Quote from Mithras :

Wow.

I didn't think the UF1 could get THAT good MPG.. Seriously.. 70?!

And the FZ surprises me as well.. It's only a 3.6L 6, but then again, it is Porsche-performance-oriented, and they don't really factor in fuel economy over performance..

True, but porsches are relatively efficient for being 300+ hp cars...they sure do not 16L/100km @ 100kmh...how high were the rpms?
Try to blow up the tires (more pressure).

^^ You need to save your posts to text documents, then you can easily copy and paste required answers as after month or week you need to write that all again as another new person comes and requires some informative answers

That is what I have planned to do but haven't never got around of it for some odd reason

Quote from theycallmeebryan :

It increases the flow of air into your engine. And what does that mean? Better volumetric efficiency.

well yes obviously
but what about the drop in efficiency from lowering the compression which should show its ugly rear end in low boost conditions ?

Quote from Shotglass :

well yes obviously
but what about the drop in efficiency from lowering the compression which should show its ugly rear end in low boost conditions ?

I said that assuming nothing else was done to the car. I said CAUTION: this is a generalization...

Maybe i really need to lay it out on a silver platter for you people...

Of course changing the compression of the pistons will change things... it will change alot of things.

...dont "obviously" me :doh:

who the hell shifts at 6000rpm on the street?

no wonder the figures are high

Quote from Stone in Focus :

who the hell shifts at 6000rpm on the street?

no wonder the figures are high

I am pretty sure shifting at 6000rpm would not nessasarily change the fuel economy. If you are WOT, then shifting at 6000rpm will give you better fuel economy then if you shift at 4000. You should constantly be in a gear which is within the power band. If you are driving down the highway, you shouldn't nessasarily be in the highest gear. The whole purpose of a transmission is to keep the engine in it's powerband, anyway.