Re: Holy crap people are misinformed
 

Randolph,

After reading your post and thinking a little, I am inclined to agree
with your logic. However, based on that logic, HOW would someone increase
the actual compression ratio, since the volume of air/fuel inside the
cylinder does not change the ratio? Enquiring minds would like to know! ;-)

Jonathan

P.S. for Jim Yanik: The reason why I am inclined to agree with Randolph is
this: Say your compression ratio is 10:1, you put ten "units" of air/fuel
mixture in the cylinder. It will be compressed to 1/10 of it's original
"size" (volume) upon combustion. If you put in 20 "units", it will be
compressed to a 20:2 ratio, which reduces back to 10:1. 30:3 reduces to
10:1, and so forth. More "units" just causes a more powerful combustion,
creating more pressure to push the piston down more forcefully.

"Randolph" <trash@junkmail.com> wrote in message
news:4134EC5B.36FE2C33@junkmail.com...
>
> Jim Yanik wrote:
>>
>> Randolph <trash@junkmail.com> wrote in
>> news:4134C5B2.3C9F8D72@junkmail.com:
>>
>> Sure it does.Compression ratio is the ratio of the volume of the cylinder
>> at BDC(bottom dead center) to volume at TDC. When you FORCE more air/fuel
>> mix into the cylinder,you effectively enlarge the volume at BDC(it acts
>> like a more voluminous cylinder),compressing down to the unchanged
>> original
>> volume at TDC,thus increasing the compression ratio.
>>
>> That's why turbos and superchargers use higher octane gasoline,because of
>> the effective higher compression ratio.
>
> Nope, the compression ratio is, as you said, the ratio of the volume of
> the cylinder
> at BDC(bottom dead center) to volume at TDC. Absolute pressure, mass of
> air, etc. makes no difference. If I keep my foot off the throttle, I
> draw a moderate vacuum in the cylinder on the intake stroke, and get a
> relatively low pressure on the compression stroke, but the compression
> ratio is the same no matter the position of the throttle. The
> compression ratio is purely a function of the engine geometry. When
> turbo charged engine typically require premium fuel, it is because the
> *pressure* is high, not because the compression ratio is high.

Re: Holy crap people are misinformed
 

"Randolph" <trash@junkmail.com> wrote in message
news:4134EC5B.36FE2C33@junkmail.com...
>
> Jim Yanik wrote:
>>
>> Randolph <trash@junkmail.com> wrote in
>> news:4134C5B2.3C9F8D72@junkmail.com:
>>
>> Sure it does.Compression ratio is the ratio of the volume of the cylinder
>> at BDC(bottom dead center) to volume at TDC. When you FORCE more air/fuel
>> mix into the cylinder,you effectively enlarge the volume at BDC(it acts
>> like a more voluminous cylinder),compressing down to the unchanged
>> original
>> volume at TDC,thus increasing the compression ratio.
>>
>> That's why turbos and superchargers use higher octane gasoline,because of
>> the effective higher compression ratio.
>
> Nope, the compression ratio is, as you said, the ratio of the volume of
> the cylinder
> at BDC(bottom dead center) to volume at TDC. Absolute pressure, mass of
> air, etc. makes no difference. If I keep my foot off the throttle, I
> draw a moderate vacuum in the cylinder on the intake stroke, and get a
> relatively low pressure on the compression stroke, but the compression
> ratio is the same no matter the position of the throttle. The
> compression ratio is purely a function of the engine geometry. When
> turbo charged engine typically require premium fuel, it is because the
> *pressure* is high, not because the compression ratio is high.

Or cams with lots of overlap....high BMEP.

Re: Holy crap people are misinformed
 

"Randolph" <trash@junkmail.com> wrote in message
news:4134EC5B.36FE2C33@junkmail.com...
>
> Jim Yanik wrote:
>>
>> Randolph <trash@junkmail.com> wrote in
>> news:4134C5B2.3C9F8D72@junkmail.com:
>>
>> Sure it does.Compression ratio is the ratio of the volume of the cylinder
>> at BDC(bottom dead center) to volume at TDC. When you FORCE more air/fuel
>> mix into the cylinder,you effectively enlarge the volume at BDC(it acts
>> like a more voluminous cylinder),compressing down to the unchanged
>> original
>> volume at TDC,thus increasing the compression ratio.
>>
>> That's why turbos and superchargers use higher octane gasoline,because of
>> the effective higher compression ratio.
>
> Nope, the compression ratio is, as you said, the ratio of the volume of
> the cylinder
> at BDC(bottom dead center) to volume at TDC. Absolute pressure, mass of
> air, etc. makes no difference. If I keep my foot off the throttle, I
> draw a moderate vacuum in the cylinder on the intake stroke, and get a
> relatively low pressure on the compression stroke, but the compression
> ratio is the same no matter the position of the throttle. The
> compression ratio is purely a function of the engine geometry. When
> turbo charged engine typically require premium fuel, it is because the
> *pressure* is high, not because the compression ratio is high.

Or cams with lots of overlap....high BMEP.

Re: Holy crap people are misinformed
 

K-town wrote:
>
> Randolph,
>
> After reading your post and thinking a little, I am inclined to agree
> with your logic. However, based on that logic, HOW would someone increase
> the actual compression ratio, since the volume of air/fuel inside the
> cylinder does not change the ratio? Enquiring minds would like to know! ;-)

To put some numbers on it, let's say you have a 1.6 liter, 4 cylinder
engine with a 9:1 compression ratio. Let's assume the bore to be about
80 mm and the stroke to be about 80 mm. That would give you a 0.4 l
displacement pr. cylinder. At bottom dead center, the total volume above
the piston would be 0.45 liter. At top dead center the volume above the
piston would be 0.05 liter. Now, let's say you grind down the bottom
side of the head 2 millimeters and stick it back on. This does not
change the displacement. It does decrease the volume above the cylinder
by about 0.01 liter, so at top dead center there would be 0.04 liter,
and at bottom dead center you would get 0.44 liter. Now the compression
ratio has increased to 0.44 / .0.4 = 11.

If you somehow could move the crankshaft up or down with respect to the
cylinders, you would also vary the compression ratio. This is just what
Saab did a few years back. See
http://www.edmunds.com/news/innovati...7/article.html

Re: Holy crap people are misinformed
 

K-town wrote:
>
> Randolph,
>
> After reading your post and thinking a little, I am inclined to agree
> with your logic. However, based on that logic, HOW would someone increase
> the actual compression ratio, since the volume of air/fuel inside the
> cylinder does not change the ratio? Enquiring minds would like to know! ;-)

To put some numbers on it, let's say you have a 1.6 liter, 4 cylinder
engine with a 9:1 compression ratio. Let's assume the bore to be about
80 mm and the stroke to be about 80 mm. That would give you a 0.4 l
displacement pr. cylinder. At bottom dead center, the total volume above
the piston would be 0.45 liter. At top dead center the volume above the
piston would be 0.05 liter. Now, let's say you grind down the bottom
side of the head 2 millimeters and stick it back on. This does not
change the displacement. It does decrease the volume above the cylinder
by about 0.01 liter, so at top dead center there would be 0.04 liter,
and at bottom dead center you would get 0.44 liter. Now the compression
ratio has increased to 0.44 / .0.4 = 11.

If you somehow could move the crankshaft up or down with respect to the
cylinders, you would also vary the compression ratio. This is just what
Saab did a few years back. See
http://www.edmunds.com/news/innovati...7/article.html

Re: Holy crap people are misinformed
 

"K-town" <jdu52580@carolina.rr.com> wrote in
news:7n7Zc.3680$683.455808@twister.southeast.rr.co m:

> Randolph,
>
> After reading your post and thinking a little, I am inclined to
> agree
> with your logic. However, based on that logic, HOW would someone
> increase the actual compression ratio, since the volume of air/fuel
> inside the cylinder does not change the ratio? Enquiring minds would
> like to know! ;-)
>
> Jonathan
>
> P.S. for Jim Yanik: The reason why I am inclined to agree with
> Randolph is this: Say your compression ratio is 10:1, you put ten
> "units" of air/fuel mixture in the cylinder. It will be compressed to
> 1/10 of it's original "size" (volume) upon combustion. If you put in
> 20 "units", it will be compressed to a 20:2 ratio, which reduces back
> to 10:1. 30:3 reduces to 10:1, and so forth. More "units" just
> causes a more powerful combustion, creating more pressure to push the
> piston down more forcefully.
>
> "Randolph" <trash@junkmail.com> wrote in message
> news:4134EC5B.36FE2C33@junkmail.com...
>>
>> Jim Yanik wrote:
>>>
>>> Randolph <trash@junkmail.com> wrote in
>>> news:4134C5B2.3C9F8D72@junkmail.com:
>>>
>>> Sure it does.Compression ratio is the ratio of the volume of the
>>> cylinder at BDC(bottom dead center) to volume at TDC. When you FORCE
>>> more air/fuel mix into the cylinder,you effectively enlarge the
>>> volume at BDC(it acts like a more voluminous cylinder),compressing
>>> down to the unchanged original
>>> volume at TDC,thus increasing the compression ratio.
>>>
>>> That's why turbos and superchargers use higher octane
>>> gasoline,because of the effective higher compression ratio.
>>
>> Nope, the compression ratio is, as you said, the ratio of the volume
>> of the cylinder
>> at BDC(bottom dead center) to volume at TDC. Absolute pressure, mass
>> of air, etc. makes no difference. If I keep my foot off the throttle,
>> I draw a moderate vacuum in the cylinder on the intake stroke, and
>> get a relatively low pressure on the compression stroke, but the
>> compression ratio is the same no matter the position of the throttle.
>> The compression ratio is purely a function of the engine geometry.
>> When turbo charged engine typically require premium fuel, it is
>> because the *pressure* is high, not because the compression ratio is
>> high.
>
>
>
>

Intake compression by turbo or supercharger is just raising the comp ratio
by external means,a variable compression ratio.(that's what I meant by
"effective".)
Just milling the head(s) of a natually aspirated motor of the same
displacement gives more HP and torque.All that changes is the comp ratio.
Otherwise,why mill heads? All it would do is require a more-
expensive,higher octane fuel.
--
Jim Yanik
jyanik-at-kua.net

Re: Holy crap people are misinformed
 

"K-town" <jdu52580@carolina.rr.com> wrote in
news:7n7Zc.3680$683.455808@twister.southeast.rr.co m:

> Randolph,
>
> After reading your post and thinking a little, I am inclined to
> agree
> with your logic. However, based on that logic, HOW would someone
> increase the actual compression ratio, since the volume of air/fuel
> inside the cylinder does not change the ratio? Enquiring minds would
> like to know! ;-)
>
> Jonathan
>
> P.S. for Jim Yanik: The reason why I am inclined to agree with
> Randolph is this: Say your compression ratio is 10:1, you put ten
> "units" of air/fuel mixture in the cylinder. It will be compressed to
> 1/10 of it's original "size" (volume) upon combustion. If you put in
> 20 "units", it will be compressed to a 20:2 ratio, which reduces back
> to 10:1. 30:3 reduces to 10:1, and so forth. More "units" just
> causes a more powerful combustion, creating more pressure to push the
> piston down more forcefully.
>
> "Randolph" <trash@junkmail.com> wrote in message
> news:4134EC5B.36FE2C33@junkmail.com...
>>
>> Jim Yanik wrote:
>>>
>>> Randolph <trash@junkmail.com> wrote in
>>> news:4134C5B2.3C9F8D72@junkmail.com:
>>>
>>> Sure it does.Compression ratio is the ratio of the volume of the
>>> cylinder at BDC(bottom dead center) to volume at TDC. When you FORCE
>>> more air/fuel mix into the cylinder,you effectively enlarge the
>>> volume at BDC(it acts like a more voluminous cylinder),compressing
>>> down to the unchanged original
>>> volume at TDC,thus increasing the compression ratio.
>>>
>>> That's why turbos and superchargers use higher octane
>>> gasoline,because of the effective higher compression ratio.
>>
>> Nope, the compression ratio is, as you said, the ratio of the volume
>> of the cylinder
>> at BDC(bottom dead center) to volume at TDC. Absolute pressure, mass
>> of air, etc. makes no difference. If I keep my foot off the throttle,
>> I draw a moderate vacuum in the cylinder on the intake stroke, and
>> get a relatively low pressure on the compression stroke, but the
>> compression ratio is the same no matter the position of the throttle.
>> The compression ratio is purely a function of the engine geometry.
>> When turbo charged engine typically require premium fuel, it is
>> because the *pressure* is high, not because the compression ratio is
>> high.
>
>
>
>

Intake compression by turbo or supercharger is just raising the comp ratio
by external means,a variable compression ratio.(that's what I meant by
"effective".)
Just milling the head(s) of a natually aspirated motor of the same
displacement gives more HP and torque.All that changes is the comp ratio.
Otherwise,why mill heads? All it would do is require a more-
expensive,higher octane fuel.
--
Jim Yanik
jyanik-at-kua.net

Re: Holy crap people are misinformed
 

Jim Yanik wrote:
> Intake compression by turbo or supercharger is just raising the comp ratio
> by external means,a variable compression ratio.(that's what I meant by
> "effective".)

NO! Turbos do not increase the *compression ratio*, turbos increase the
pressure! Variable pressure, yes. Variable compression ratio, no. The
term "compression ratio" is well defined, and reaaly is not open for
interpretation.

Re: Holy crap people are misinformed
 

Jim Yanik wrote:
> Intake compression by turbo or supercharger is just raising the comp ratio
> by external means,a variable compression ratio.(that's what I meant by
> "effective".)

NO! Turbos do not increase the *compression ratio*, turbos increase the
pressure! Variable pressure, yes. Variable compression ratio, no. The
term "compression ratio" is well defined, and reaaly is not open for
interpretation.

Re: Holy crap people are misinformed
 

On Wed, 1 Sep 2004 01:37:11 +0000 (UTC), Jim Yanik <jyanik@abuse.gov>
wrote:
>"K-town" <jdu52580@carolina.rr.com> wrote in
>news:7n7Zc.3680$683.455808@twister.southeast.rr.c om:
>
>> Randolph,
>>
>> After reading your post and thinking a little, I am inclined to
>> agree
>> with your logic. However, based on that logic, HOW would someone
>> increase the actual compression ratio, since the volume of air/fuel
>> inside the cylinder does not change the ratio? Enquiring minds would
>> like to know! ;-)
>>
>> Jonathan
>>
>> P.S. for Jim Yanik: The reason why I am inclined to agree with
>> Randolph is this: Say your compression ratio is 10:1, you put ten
>> "units" of air/fuel mixture in the cylinder. It will be compressed to
>> 1/10 of it's original "size" (volume) upon combustion. If you put in
>> 20 "units", it will be compressed to a 20:2 ratio, which reduces back
>> to 10:1. 30:3 reduces to 10:1, and so forth. More "units" just
>> causes a more powerful combustion, creating more pressure to push the
>> piston down more forcefully.

No.

>> "Randolph" <trash@junkmail.com> wrote in message
>> news:4134EC5B.36FE2C33@junkmail.com...
>>>
>>> Jim Yanik wrote:
>>>>
>>>> Randolph <trash@junkmail.com> wrote in
>>>> news:4134C5B2.3C9F8D72@junkmail.com:
>>>>
>>>> Sure it does.Compression ratio is the ratio of the volume of the
>>>> cylinder at BDC(bottom dead center) to volume at TDC. When you FORCE
>>>> more air/fuel mix into the cylinder,you effectively enlarge the
>>>> volume at BDC(it acts like a more voluminous cylinder),compressing
>>>> down to the unchanged original
>>>> volume at TDC,thus increasing the compression ratio.
>>>>
>>>> That's why turbos and superchargers use higher octane
>>>> gasoline,because of the effective higher compression ratio.
>>>
>>> Nope, the compression ratio is, as you said, the ratio of the volume
>>> of the cylinder
>>> at BDC(bottom dead center) to volume at TDC. Absolute pressure, mass
>>> of air, etc. makes no difference. If I keep my foot off the throttle,
>>> I draw a moderate vacuum in the cylinder on the intake stroke, and
>>> get a relatively low pressure on the compression stroke, but the
>>> compression ratio is the same no matter the position of the throttle.
>>> The compression ratio is purely a function of the engine geometry.
>>> When turbo charged engine typically require premium fuel, it is
>>> because the *pressure* is high, not because the compression ratio is
>>> high.
>
>Intake compression by turbo or supercharger is just raising the comp ratio
>by external means,a variable compression ratio.(that's what I meant by
>"effective".)

No.

>Just milling the head(s) of a natually aspirated motor of the same
>displacement gives more HP and torque.All that changes is the comp ratio.
>Otherwise,why mill heads? All it would do is require a more-
>expensive,higher octane fuel.

No... No, No, No.

Assume the idealized hypothetical where the full volume of a cylinder
full of fuel-air mixtures is at 1 atmosphere pressure as the valves
close and the piston begins its compression stroke; the compression
ratio is determined by dividing the volume of the cylinder at TDC
(say 40cc) by the volume of the cylinder at BDC (say 400cc).

Now assume a circumstance where a turbo charger or supercharger has
filled the same cylinder, just as the valves close and the piston
begins its compression stroke, with fuel-air mixture at 2 atmospheres
pressure; the compression ratio is still determined by dividing the
volume of the cylinder at TDC (still 40cc) by the volume of the
cylinder at BDC (still 400cc).

No change in compression ratio, no mysterious "units".

- So why more power from turbo/super charging?

Basic physical chemistry: At constant volume and temperature there
will be twice as much fuel and air in the cylinder at twice the
pressure. (The Ideal Gas Law: PV=nRT, where P,V,T, and n are
Pressure, Volume, Temperature, and amount of the gas with R as the gas
constant.)
&
Simple thermodynamics: Twice the fuel-air - "twice" the power.

- Why does increased compression ratio yield increased power?

Basic combustion science: The greater the density and temperature of
the fuel-air charge, the more efficiently it burns.

Re: Holy crap people are misinformed
 

On Wed, 1 Sep 2004 01:37:11 +0000 (UTC), Jim Yanik <jyanik@abuse.gov>
wrote:
>"K-town" <jdu52580@carolina.rr.com> wrote in
>news:7n7Zc.3680$683.455808@twister.southeast.rr.c om:
>
>> Randolph,
>>
>> After reading your post and thinking a little, I am inclined to
>> agree
>> with your logic. However, based on that logic, HOW would someone
>> increase the actual compression ratio, since the volume of air/fuel
>> inside the cylinder does not change the ratio? Enquiring minds would
>> like to know! ;-)
>>
>> Jonathan
>>
>> P.S. for Jim Yanik: The reason why I am inclined to agree with
>> Randolph is this: Say your compression ratio is 10:1, you put ten
>> "units" of air/fuel mixture in the cylinder. It will be compressed to
>> 1/10 of it's original "size" (volume) upon combustion. If you put in
>> 20 "units", it will be compressed to a 20:2 ratio, which reduces back
>> to 10:1. 30:3 reduces to 10:1, and so forth. More "units" just
>> causes a more powerful combustion, creating more pressure to push the
>> piston down more forcefully.

No.

>> "Randolph" <trash@junkmail.com> wrote in message
>> news:4134EC5B.36FE2C33@junkmail.com...
>>>
>>> Jim Yanik wrote:
>>>>
>>>> Randolph <trash@junkmail.com> wrote in
>>>> news:4134C5B2.3C9F8D72@junkmail.com:
>>>>
>>>> Sure it does.Compression ratio is the ratio of the volume of the
>>>> cylinder at BDC(bottom dead center) to volume at TDC. When you FORCE
>>>> more air/fuel mix into the cylinder,you effectively enlarge the
>>>> volume at BDC(it acts like a more voluminous cylinder),compressing
>>>> down to the unchanged original
>>>> volume at TDC,thus increasing the compression ratio.
>>>>
>>>> That's why turbos and superchargers use higher octane
>>>> gasoline,because of the effective higher compression ratio.
>>>
>>> Nope, the compression ratio is, as you said, the ratio of the volume
>>> of the cylinder
>>> at BDC(bottom dead center) to volume at TDC. Absolute pressure, mass
>>> of air, etc. makes no difference. If I keep my foot off the throttle,
>>> I draw a moderate vacuum in the cylinder on the intake stroke, and
>>> get a relatively low pressure on the compression stroke, but the
>>> compression ratio is the same no matter the position of the throttle.
>>> The compression ratio is purely a function of the engine geometry.
>>> When turbo charged engine typically require premium fuel, it is
>>> because the *pressure* is high, not because the compression ratio is
>>> high.
>
>Intake compression by turbo or supercharger is just raising the comp ratio
>by external means,a variable compression ratio.(that's what I meant by
>"effective".)

No.

>Just milling the head(s) of a natually aspirated motor of the same
>displacement gives more HP and torque.All that changes is the comp ratio.
>Otherwise,why mill heads? All it would do is require a more-
>expensive,higher octane fuel.

No... No, No, No.

Assume the idealized hypothetical where the full volume of a cylinder
full of fuel-air mixtures is at 1 atmosphere pressure as the valves
close and the piston begins its compression stroke; the compression
ratio is determined by dividing the volume of the cylinder at TDC
(say 40cc) by the volume of the cylinder at BDC (say 400cc).

Now assume a circumstance where a turbo charger or supercharger has
filled the same cylinder, just as the valves close and the piston
begins its compression stroke, with fuel-air mixture at 2 atmospheres
pressure; the compression ratio is still determined by dividing the
volume of the cylinder at TDC (still 40cc) by the volume of the
cylinder at BDC (still 400cc).

No change in compression ratio, no mysterious "units".

- So why more power from turbo/super charging?

Basic physical chemistry: At constant volume and temperature there
will be twice as much fuel and air in the cylinder at twice the
pressure. (The Ideal Gas Law: PV=nRT, where P,V,T, and n are
Pressure, Volume, Temperature, and amount of the gas with R as the gas
constant.)
&
Simple thermodynamics: Twice the fuel-air - "twice" the power.

- Why does increased compression ratio yield increased power?

Basic combustion science: The greater the density and temperature of
the fuel-air charge, the more efficiently it burns.

Re: Holy crap people are misinformed
 

<snip>
>
> No change in compression ratio, no mysterious "units".
>
<snip>

The reason why I said "units" is because you could use any method of
measurement you like; English or Metric. Most use metric, so you would use
milliliters (or cubic centimeters; 1mL = 1cc) of fuel & air. But if someone
wanted to use cubic inches, the same mathematical formula would be used to
calculate the ratio and/or pressure.

Re: Holy crap people are misinformed
 

<snip>
>
> No change in compression ratio, no mysterious "units".
>
<snip>

The reason why I said "units" is because you could use any method of
measurement you like; English or Metric. Most use metric, so you would use
milliliters (or cubic centimeters; 1mL = 1cc) of fuel & air. But if someone
wanted to use cubic inches, the same mathematical formula would be used to
calculate the ratio and/or pressure.

Re: Holy crap people are misinformed
 

On Wed, 01 Sep 2004 13:06:06 GMT, "K-town" <jdu52580@carolina.rr.com>
wrote:
><snip>
>>
>> No change in compression ratio, no mysterious "units".
>>
><snip>
>
>The reason why I said "units" is because you could use any method of
>measurement you like; English or Metric. Most use metric, so you would use
>milliliters (or cubic centimeters; 1mL = 1cc) of fuel & air. But if someone
>wanted to use cubic inches, the same mathematical formula would be used to
>calculate the ratio and/or pressure.

Yeah... I'm not buying it.

You claimed a turbocharger will double the number of "units" of volume
in a cylinder: That is patently false and incorrect. Whether
measured in cc, ci, cubic fish eyes or ping pong balls; the swept
volume of a cylinder, the volume of the combustion chamber, and
thereby the compression ratio, all are rigidly fixed in any production
automobile and cannot be varied without major mechanical modification.

A turbo/supercharger only increases the pressure of the fuel-air
mixture in the quite fixed maximum volume of a cylinder. By
increasing the pressure of the air-fuel mixture the density is
increased, resulting in an increase in the amount of fuel and air
available for combustion.

PV=nRT. It's perhaps the primary physical law.

The swept volume stays quite constant, the combustion chamber volume
stays quite constant, the compression ratio stays quite constant:

It is NOT rocket surgery.

Re: Holy crap people are misinformed
 

On Wed, 01 Sep 2004 13:06:06 GMT, "K-town" <jdu52580@carolina.rr.com>
wrote:
><snip>
>>
>> No change in compression ratio, no mysterious "units".
>>
><snip>
>
>The reason why I said "units" is because you could use any method of
>measurement you like; English or Metric. Most use metric, so you would use
>milliliters (or cubic centimeters; 1mL = 1cc) of fuel & air. But if someone
>wanted to use cubic inches, the same mathematical formula would be used to
>calculate the ratio and/or pressure.

Yeah... I'm not buying it.

You claimed a turbocharger will double the number of "units" of volume
in a cylinder: That is patently false and incorrect. Whether
measured in cc, ci, cubic fish eyes or ping pong balls; the swept
volume of a cylinder, the volume of the combustion chamber, and
thereby the compression ratio, all are rigidly fixed in any production
automobile and cannot be varied without major mechanical modification.

A turbo/supercharger only increases the pressure of the fuel-air
mixture in the quite fixed maximum volume of a cylinder. By
increasing the pressure of the air-fuel mixture the density is
increased, resulting in an increase in the amount of fuel and air
available for combustion.

PV=nRT. It's perhaps the primary physical law.

The swept volume stays quite constant, the combustion chamber volume
stays quite constant, the compression ratio stays quite constant:

It is NOT rocket surgery.