[Shane303]

I am (have been) curious about why people think that the level of "boost" an engine receives from forced induction equates to the amount of power it outputs. Is it just a general thought that air pressure=power? Is this a sign that the individual doesn't understand engines/tuning?

[C.Pop]

Well yeah, few people realize it's about flow, but all else equal, more boost means more flow, which should mean more power. This is a common issue here and on every other platform.

[135Pats]

It means most people don't know much about the subject matter. Is what it is.

'Boost' is a measure of pressure, has absolutely nothing to do with power. Arbitrary references to boost without full context mean very little.

[Antetokounmpo]

More air=more power. More boost, more air.

[mike@x-ph.com]

Originally Posted by Shane303

I am (have been) curious about why people think that the level of "boost" an engine receives from forced induction equates to the amount of power it outputs. Is it just a general thought that air pressure=power? Is this a sign that the individual doesn't understand engines/tuning?

Some get it, others dont .. But in terms of results, more boost equals more power

[derryck]

Probably because on factory boosted cars, increased boost generally equates to significant power (output) increases. But feel free to show everyone how smart you are.

[Jeff@TopGearSolutions]

Boost alone does not = power

There is more into the equation.

Velocity of the air, CFM ETC

Most people dont understand boost fully.

I look at it like this.

What has more air in a tire, 30 PSI spare or a 30 PSI in a 18 wheeler truck tire.

That's why boost is not the end all when it comes to how much air / power.

You can probably google a much better explanation then that too.

[B@man335]

But when people make the claim more boost = more power, they mean all things generally being equal. If you take any fi engine and run two different boost pressures, the higher boost will put out more power

[Nitrousbird]

Originally Posted by B@man335

If you take any fi engine and run two different boost pressures, the higher boost will put out more power

Not if you have to pull a pile of timing in order to do it. If you increase boost pressure by same 4psi, but have much higher IAT and have to pull a lot of timing, you could technically make the same or less power.

[Jeff@TopGearSolutions]

Yea increasing boost only makes more power if you are not on the knock threshold and the IAT aren't through the roof.

You can throw in more boost and potentially lose hp by either having to combat IAT or reducing timing for knock.

It really depends.

In the case of a stock vehicle, yea increasing boost about 7 psi all things else equal will yield more power.

Going out efficiency or 3x-4x stock boost pressure, depends.

Best answer is it depends.

[B@man335]

Originally Posted by Nitrousbird

Not if you have to pull a pile of timing in order to do it. If you increase boost pressure by same 4psi, but have much higher IAT and have to pull a lot of timing, you could technically make the same or less power.

Correct but then we're getting into mbt which a majority of the guys here don't reach. Which is the exception. Is it not fair to say that "generally" increased boost = more power?

[3pointohhhh]

I would say that the average person who has not worked on a turbo car or taken mechanics classes has no idea how boost equates to power anyways. I remember when I first got into cars and didn't understand the intricacies of turbos I would ask the same dumb question all other noobs ask, "how much boost are you running?"
Just because somebody owns a turbo car or likes turbo cars, does not inherently mean they understand anything about compressor wheels and turbo sizes. Psi numbers are irrelevant when you don't know the turbo in the car.
However, I would say the majority of the time the average 335 owner says, "how much boost are you running?" it is because he assumes you have stock turbos and is curious how your particular tune compares to his.
If, though, you are seeking merely to educate the masses, there are less Bimmer (douchy) ways to phrase your point.

[csu87]

why is this a thread?

I feel like OP got schooled by someone about this and now is trying to act smart.

No, higher boost doesnt always = more power, but everything else the same, it does. And generally if you are talking to an enthusiast, they will know the size of the turbo you are running and roughly what it equates to if you tell them the psi. If you are talking to a moron with an eclipse and a "HUGE TURBO BRAH", then no, they probably dont understand.

[Shane303]

Originally Posted by derryck

Probably because on factory boosted cars, increased boost generally equates to significant power (output) increases. But feel free to show everyone how smart you are.

Thank you for your permission.

why is this a thread?

I feel like OP got schooled by someone about this and now is trying to act smart.

No, higher boost doesnt always = more power, but everything else the same, it does. And generally if you are talking to an enthusiast, they will know the size of the turbo you are running and roughly what it equates to if you tell them the psi. If you are talking to a moron with an eclipse and a "HUGE TURBO BRAH", then no, they probably dont understand.

Nailed this one... it's like you were the person doing the schooling.

I would say that the average person who has not worked on a turbo car or taken mechanics classes has no idea how boost equates to power anyways. I remember when I first got into cars and didn't understand the intricacies of turbos I would ask the same dumb question all other noobs ask, "how much boost are you running?"
Just because somebody owns a turbo car or likes turbo cars, does not inherently mean they understand anything about compressor wheels and turbo sizes. Psi numbers are irrelevant when you don't know the turbo in the car.
However, I would say the majority of the time the average 335 owner says, "how much boost are you running?" it is because he assumes you have stock turbos and is curious how your particular tune compares to his.
If, though, you are seeking merely to educate the masses, there are less Bimmer (douchy) ways to phrase your point.

If I can get the point across to a few of the people that now own a turbo BMW, while being "douchy", I consider this a successful thread.

To the select few that had a great reply/post that was actually beneficial to the thread... Thank you, it's very odd to see people adding to a thread positively.

[007_e350]

how much are you guys boosting ?

[Torgus]

Originally Posted by Shane303

I am (have been) curious about why people think that the level of "boost" an engine receives from forced induction equates to the amount of power it outputs. Is it just a general thought that air pressure=power? Is this a sign that the individual doesn't understand engines/tuning?

Because it does? It's the easiest way to equate boost to whp/tq. obviously if you are blowing super hot air it's not going to help.

If we both have the same engine, manifold, turbo, etc. you can basically use boost to figure out power output at the flywheel/wheels. Since 99% of the forum is on stock turbos most people talk about boost in relation to power as it applies to most of the people's cars. If I'm running 18psi to redline and you are running 10psi to redline and all things being equal you can estimate or judge the power output at a certain rpm based on boost alone.

Feel free to come up with an easier way to equate power to the wheels.


edit: Let me put it this way. If I know you have a 6466 on an N54 with PI E85 knowing the peak boost is a quick way to estimate power to the wheels. People use the term boost as a quick way to reference potential power output.

[Jeff@TopGearSolutions]

Originally Posted by 007_e350

how much are you guys boosting ?

All of them...

[BSM n54iS]

Originally Posted by csu87

why is this a thread?

I feel like OP got schooled by someone about this and now is trying to act smart.

No, higher boost doesnt always = more power, but everything else the same, it does. And generally if you are talking to an enthusiast, they will know the size of the turbo you are running and roughly what it equates to if you tell them the psi. If you are talking to a moron with an eclipse and a "HUGE TURBO BRAH", then no, they probably dont understand.

Seemed like a sneakily worded question by OP to mask his own confusion on the subject..

[Shane303]

Originally Posted by Torgus

Because it does? It's the easiest way to equate boost to whp/tq. obviously if you are blowing super hot air it's not going to help.

If we both have the same engine, manifold, turbo, etc. you can basically use boost to figure out power output at the flywheel/wheels. Since 99% of the forum is on stock turbos most people talk about boost in relation to power as it applies to most of the people's cars. If I'm running 18psi to redline and you are running 10psi to redline and all things being equal you can estimate or judge the power output at a certain rpm based on boost alone.

Feel free to come up with an easier way to equate power to the wheels.


edit: Let me put it this way. If I know you have a 6466 on an N54 with PI E85 knowing the peak boost is a quick way to estimate power to the wheels. People use the term boost as a quick way to reference potential power output.

So if I have a 6466 on an N54 20psi of boost, how much HP would you think the car is making?

How much is the car making with 20psi AND 14 degrees of timing advance, what about 20 psi with 0 degrees?

I hope that we can agree that if you were to raise boost pressure on ANY engine, and JUST boost pressure, that would make minimal power additions.

The point was that MANY people think the more boost pressure they put into an engine=more power. There are way too many other variables to consider than boost alone. A lot of the questions on the forum are "how much boost does this map make?" and that is what prompted this thread/discussion was to help "spread the gospel" and educate the select few who read it.

[Torgus]

20 psi with 0 degrees is easy you arn't making shit because your engine just popped from a super lean condition

If you care so much why don't you go write an article on this and then link it to the forums and educate people?

AGAIN as stated above and by others boost is just a quick way to estimate power. I agree with csu87

[Shane303]

Originally Posted by Torgus

20 psi with 0 degrees is easy you arn't making shit because your engine just popped from a super lean condition

If you care so much why don't you go write an article on this and then link it to the forums and educate people?

AGAIN as stated above and by others boost is just a quick way to estimate power. I agree with csu87

What?!

[Torgus]

Originally Posted by Shane303

What?!

Sorry I'm still hungover, it was a long late night.

ignition timing at 0 it will produce less power as the piston is already moving down. No one would ever do this on purpose afaik. I think it also would probably he harder to start.