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Herman and Operation 30MPG

Help, Advice and DIY Tutorials on Volvo's extremely popular car line -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.
1992 - 1997 850, 850 R, 850 T5-R, 850 T5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70
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Rattnalle
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Re: Herman and Operation 30MPG

Post by Rattnalle » Tue Mar 13, 2018 12:08 pm

The ecu is always adjusting for pre ignition regardless of fuel. But yes the more it adjusts the more performance you lose of course.

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abscate
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Re: Herman and Operation 30MPG

Post by abscate » Tue Mar 13, 2018 12:27 pm

My 1999 manual says I should put in 91 octane (that is the US 91) with the minimum requirement of 87.

My 99 turbo has a compression ratio of 8.5:1

My 05 NA has a ratio of 10.5:1

Im a bit less picky about the 99 as I drive it off boost for 95% of the time. The 05 gets 91 or 93 depending on how rich I feel.
1 SWMBO for 30 years
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5 cats/dogs/gears
6 Perfect Ladies in waiting
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8 Boats- with a big pointy metal thing on top

1999 V70 T5M 56 2005 V70 NA M56 VWs BMW

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June
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Re: Herman and Operation 30MPG

Post by June » Tue Mar 13, 2018 1:05 pm

abscate wrote:
Tue Mar 13, 2018 12:27 pm
My 1999 manual says I should put in 91 octane (that is the US 91) with the minimum requirement of 87.

My 99 turbo has a compression ratio of 8.5:1

My 05 NA has a ratio of 10.5:1

Im a bit less picky about the 99 as I drive it off boost for 95% of the time. The 05 gets 91 or 93 depending on how rich I feel.
Correct me if I am wrong, but the 8.5:1 increases durring boost and is the reason turbo engines don't have 10.5:1 as a starting point? June
My Volvo cars owned
1989 740 GLT ordered
1994 850 4door standard shift ordered
1996 960 ordered
1998 S90 ordered totalled after 3 weeks
1998 V70 GT dealer stock car
2002 S80 T6 ordered totalled
2004 S80 T6 dealer stock car and current car owned

User avatar
Rattnalle
Posts: 1031
Joined: Fri Sep 01, 2017 2:10 am
Year and Model: 2004 V70 2.5T
Location: Sweden
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Re: Herman and Operation 30MPG

Post by Rattnalle » Tue Mar 13, 2018 2:05 pm

June wrote:
Tue Mar 13, 2018 1:05 pm
abscate wrote:
Tue Mar 13, 2018 12:27 pm
My 1999 manual says I should put in 91 octane (that is the US 91) with the minimum requirement of 87.

My 99 turbo has a compression ratio of 8.5:1

My 05 NA has a ratio of 10.5:1

Im a bit less picky about the 99 as I drive it off boost for 95% of the time. The 05 gets 91 or 93 depending on how rich I feel.
Correct me if I am wrong, but the 8.5:1 increases durring boost and is the reason turbo engines don't have 10.5:1 as a starting point? June
Effectively compared to atmosphere pressure, yes. So a turbo will lose more performance relative to its max output when the boost kicks in if it detects pre ignition due to poor fuel.

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abscate
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Re: Herman and Operation 30MPG

Post by abscate » Tue Mar 13, 2018 2:20 pm

The compression ratio, formally defined, of the engine is constant but there will be higher pressure in the cylinder in a turbo, so it is effectively a higher compression ratio. Im not sure how much extra charge a turbo pushes into a cylinder - sounds googleable though.
1 SWMBO for 30 years
2 Volvos
3 VWs
4 Careers
5 cats/dogs/gears
6 Perfect Ladies in waiting
7 Drivers
8 Boats- with a big pointy metal thing on top

1999 V70 T5M 56 2005 V70 NA M56 VWs BMW

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Rattnalle
Posts: 1031
Joined: Fri Sep 01, 2017 2:10 am
Year and Model: 2004 V70 2.5T
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Re: Herman and Operation 30MPG

Post by Rattnalle » Tue Mar 13, 2018 2:26 pm

abscate wrote:
Tue Mar 13, 2018 2:20 pm
The compression ratio, formally defined, of the engine is constant but there will be higher pressure in the cylinder in a turbo, so it is effectively a higher compression ratio. Im not sure how much extra charge a turbo pushes into a cylinder - sounds googleable though.
How much depends on the car and how high the boost pressure is. But yes it seems googlable, I just did and found a bunch of articles discussing static vs effective compression ratio though I didn't read them.

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abscate
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Re: Herman and Operation 30MPG

Post by abscate » Tue Mar 13, 2018 2:28 pm

Rattnalle wrote:
Tue Mar 13, 2018 2:26 pm
abscate wrote:
Tue Mar 13, 2018 2:20 pm
The compression ratio, formally defined, of the engine is constant but there will be higher pressure in the cylinder in a turbo, so it is effectively a higher compression ratio. Im not sure how much extra charge a turbo pushes into a cylinder - sounds googleable though.
How much depends on the car and how high the boost pressure is. But yes it seems googlable, I just did and found a bunch of articles discussing static vs effective compression ratio though I didn't read them.
I was hoping to get someone else to jump into he sinkhole of people talking about this stuff without having a clue of knowledge

:D :D :D :D
1 SWMBO for 30 years
2 Volvos
3 VWs
4 Careers
5 cats/dogs/gears
6 Perfect Ladies in waiting
7 Drivers
8 Boats- with a big pointy metal thing on top

1999 V70 T5M 56 2005 V70 NA M56 VWs BMW

User avatar
Rattnalle
Posts: 1031
Joined: Fri Sep 01, 2017 2:10 am
Year and Model: 2004 V70 2.5T
Location: Sweden
Has thanked: 8 times
Been thanked: 75 times
Sweden

Re: Herman and Operation 30MPG

Post by Rattnalle » Tue Mar 13, 2018 2:30 pm

abscate wrote:
Tue Mar 13, 2018 2:28 pm
Rattnalle wrote:
Tue Mar 13, 2018 2:26 pm
abscate wrote:
Tue Mar 13, 2018 2:20 pm
The compression ratio, formally defined, of the engine is constant but there will be higher pressure in the cylinder in a turbo, so it is effectively a higher compression ratio. Im not sure how much extra charge a turbo pushes into a cylinder - sounds googleable though.
How much depends on the car and how high the boost pressure is. But yes it seems googlable, I just did and found a bunch of articles discussing static vs effective compression ratio though I didn't read them.
I was hoping to get someone else to jump into he sinkhole of people talking about this stuff without having a clue of knowledge

:D :D :D :D
It's what I do professionally :D

User avatar
June
Posts: 1032
Joined: Wed May 04, 2016 11:18 am
Year and Model: 2004 S80 T6
Location: Jacksonville, Florida
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United States of America

Re: Herman and Operation 30MPG

Post by June » Tue Mar 13, 2018 3:01 pm

abscate wrote:
Tue Mar 13, 2018 2:28 pm
Rattnalle wrote:
Tue Mar 13, 2018 2:26 pm
abscate wrote:
Tue Mar 13, 2018 2:20 pm
The compression ratio, formally defined, of the engine is constant but there will be higher pressure in the cylinder in a turbo, so it is effectively a higher compression ratio. Im not sure how much extra charge a turbo pushes into a cylinder - sounds googleable though.
How much depends on the car and how high the boost pressure is. But yes it seems googlable, I just did and found a bunch of articles discussing static vs effective compression ratio though I didn't read them.
I was hoping to get someone else to jump into he sinkhole of people talking about this stuff without having a clue of knowledge

:D :D :D :D
It's a lot more fun than discussing vacuum cleaner vs broom. Oh wait I ride the latter! :lol: :lol: :lol: :lol: :lol: :lol: :lol: June
My Volvo cars owned
1989 740 GLT ordered
1994 850 4door standard shift ordered
1996 960 ordered
1998 S90 ordered totalled after 3 weeks
1998 V70 GT dealer stock car
2002 S80 T6 ordered totalled
2004 S80 T6 dealer stock car and current car owned

User avatar
Rattnalle
Posts: 1031
Joined: Fri Sep 01, 2017 2:10 am
Year and Model: 2004 V70 2.5T
Location: Sweden
Has thanked: 8 times
Been thanked: 75 times
Sweden

Re: Herman and Operation 30MPG

Post by Rattnalle » Tue Mar 13, 2018 3:08 pm

June wrote:
Tue Mar 13, 2018 3:01 pm
abscate wrote:
Tue Mar 13, 2018 2:28 pm
Rattnalle wrote:
Tue Mar 13, 2018 2:26 pm

How much depends on the car and how high the boost pressure is. But yes it seems googlable, I just did and found a bunch of articles discussing static vs effective compression ratio though I didn't read them.
I was hoping to get someone else to jump into he sinkhole of people talking about this stuff without having a clue of knowledge

:D :D :D :D
It's a lot more fun than discussing vacuum cleaner vs broom. Oh wait I ride the latter! :lol: :lol: :lol: :lol: :lol: :lol: :lol: June
A vacuum cleaner is a turbo charged broom ;-)

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