BMW 1 Series Coupe Forum / 1 Series Convertible Forum (1M / tii / 135i / 128i / Coupe / Cabrio / Hatchback) (BMW E82 E88 128i 130i 135i)
 





 

Post Reply
 
Thread Tools Search this Thread
      06-14-2018, 01:58 PM   #1
tellreded
New Member
2
Rep
19
Posts

Drives: E82 N52
Join Date: Feb 2018
Location: Canada

iTrader: (0)

101 octane?

Lucas oils has an illegal 7 octane level booster. That plus Petro Canada 94 would give me 101 octane. So my question is would this blow up my car? It's got just under 50000 kms on the engine, 144000 on the rest. I feel like it's be kinda dumb, but I wanna see what kind of speed I could get out of 101 octane.
Appreciate 0
      06-14-2018, 02:04 PM   #2
gjm120
Captain
United_States
433
Rep
928
Posts

Drives: 2013 128i
Join Date: Jan 2016
Location: East Texas

iTrader: (0)

I don't think much more. The N52 (like many motors) effectively adjusts compression ratio by altering ignition timing. I think the N52 is 11:1 and won't go above that as that is the piston upstroke limit.

Also kind of doubt 7 pt boost without TEL.

awaiting corrections.....
__________________
E82 Non-Sport / Ver Red / Blk Boston L / BMWP Springs w/ Koni Yellows / M front control arms / AT / Sport seats & steering wheel + paddles / HK / Nav
Appreciate 0
      06-14-2018, 02:14 PM   #3
02Pilot
Malcontent
02Pilot's Avatar
121
Rep
212
Posts

Drives: 128i
Join Date: Jul 2017
Location: NY

iTrader: (0)

Compression ratio is fixed by crankshaft stroke, deck height, and combustion chamber dimensions. The DME alters ignition timing based on pre-ignition as detected by knock sensors; pre-ignition, or knocking, is impacted by the octane rating of the fuel.

Octane is frequently misunderstood. It is only a measure of the resistance of the fuel to pre-ignition, i.e., higher octane fuels are more resistant to ignition. This allows higher compression and cylinder temps to be utilized to increase specific output. All things being equal, octane by itself has no impact on power.
__________________
Life's tough. It's tougher when you're stupid. -John Wayne
Appreciate 1
BimmerAg373.00

      06-14-2018, 02:16 PM   #4
MightyMouseTech
Brigadier General
MightyMouseTech's Avatar
2975
Rep
4,967
Posts

Drives: 13 135i 6MT LeMans Blue MSport
Join Date: Feb 2013
Location: Ottawa, Canada

iTrader: (0)

Quote:
Originally Posted by gjm120 View Post
I don't think much more. The N52 (like many motors) effectively adjusts compression ratio by altering ignition timing. I think the N52 is 11:1 and won't go above that as that is the piston upstroke limit.

Also kind of doubt 7 pt boost without TEL.

awaiting corrections.....
Uh, you can't change the compression ratio.

As for OP, it won't make the slightest difference except removing cash from your wallet.
Appreciate 1
      06-14-2018, 02:49 PM   #5
gjm120
Captain
United_States
433
Rep
928
Posts

Drives: 2013 128i
Join Date: Jan 2016
Location: East Texas

iTrader: (0)

I said effectively changes compression ratio with ignition timing, ie not firing at TDC
__________________
E82 Non-Sport / Ver Red / Blk Boston L / BMWP Springs w/ Koni Yellows / M front control arms / AT / Sport seats & steering wheel + paddles / HK / Nav
Appreciate 0
      06-14-2018, 03:01 PM   #6
MightyMouseTech
Brigadier General
MightyMouseTech's Avatar
2975
Rep
4,967
Posts

Drives: 13 135i 6MT LeMans Blue MSport
Join Date: Feb 2013
Location: Ottawa, Canada

iTrader: (0)

Quote:
Originally Posted by gjm120 View Post
I said effectively changes compression ratio with ignition timing, ie not firing at TDC
No engine ever fires at TDC.
Appreciate 0
      06-14-2018, 03:03 PM   #7
gjm120
Captain
United_States
433
Rep
928
Posts

Drives: 2013 128i
Join Date: Jan 2016
Location: East Texas

iTrader: (0)

Quote:
Originally Posted by MightyMouseTech View Post
No engine ever fires at TDC.
Ok - so fires further advanced or retarded from TDC. Is that correct now?
__________________
E82 Non-Sport / Ver Red / Blk Boston L / BMWP Springs w/ Koni Yellows / M front control arms / AT / Sport seats & steering wheel + paddles / HK / Nav
Appreciate 0
      06-14-2018, 03:36 PM   #8
02Pilot
Malcontent
02Pilot's Avatar
121
Rep
212
Posts

Drives: 128i
Join Date: Jul 2017
Location: NY

iTrader: (0)

Quote:
Originally Posted by gjm120 View Post
Ok - so fires further advanced or retarded from TDC. Is that correct now?
The compression ratio is fixed. It is not altered, effectively or otherwise. Altering ignition timing changes when the fuel-air mixture is ignited and thus the amount of force imparted on the piston on the downstroke.

To the OP, the simple way to see what - if anything - it's doing is to dump it in and monitor the total timing advance while running at WOT, obviously after doing a control run without it. Any other method is speculative and pointless.
__________________
Life's tough. It's tougher when you're stupid. -John Wayne
Appreciate 0
      06-14-2018, 04:17 PM   #9
gjm120
Captain
United_States
433
Rep
928
Posts

Drives: 2013 128i
Join Date: Jan 2016
Location: East Texas

iTrader: (0)

Quote:
Originally Posted by 02Pilot View Post
The compression ratio is fixed. It is not altered, effectively or otherwise. Altering ignition timing changes when the fuel-air mixture is ignited and thus the amount of force imparted on the piston on the downstroke.

To the OP, the simple way to see what - if anything - it's doing is to dump it in and monitor the total timing advance while running at WOT, obviously after doing a control run without it. Any other method is speculative and pointless.
Lower octane fuel causes the knock sensor to retard ignition. This causes more of the combustion to happen on the down stroke (when the combustion chamber is larger). To me this is effectively changing compression ratio. Maybe just semantics.

Not trying to be a pain, just want to understand. Once long ago I learned how to test octane on both a research and motor index engines. And I think ,back then at least, you adjusted the combustion chamber mechanically after running the reference fuel iso-octane.
__________________
E82 Non-Sport / Ver Red / Blk Boston L / BMWP Springs w/ Koni Yellows / M front control arms / AT / Sport seats & steering wheel + paddles / HK / Nav
Appreciate 0
      06-14-2018, 05:24 PM   #10
02Pilot
Malcontent
02Pilot's Avatar
121
Rep
212
Posts

Drives: 128i
Join Date: Jul 2017
Location: NY

iTrader: (0)

OK, let's be clear about this. It may seem like semantics, but it's not. There are two types of compression ratios: static and dynamic. Static is the basic one that most people refer to, and is simply the calculated ratio between minimum and maximum cylinder volume. Dynamic compression is calculated from when the intake valves close rather than the bottom of the stroke, and may vary if the engine in question has variable cam timing.

Ignition timing has nothing to do with it. Compression is about the volume of the cylinder and how much the gases in it are squeezed. When they are ignited, or indeed if they are ignited at all, is immaterial.
__________________
Life's tough. It's tougher when you're stupid. -John Wayne
Appreciate 1
BimmerAg373.00

      06-14-2018, 06:15 PM   #11
gjm120
Captain
United_States
433
Rep
928
Posts

Drives: 2013 128i
Join Date: Jan 2016
Location: East Texas

iTrader: (0)

Quote:
Originally Posted by 02Pilot View Post
OK, let's be clear about this. It may seem like semantics, but it's not. There are two types of compression ratios: static and dynamic. Static is the basic one that most people refer to, and is simply the calculated ratio between minimum and maximum cylinder volume. Dynamic compression is calculated from when the intake valves close rather than the bottom of the stroke, and may vary if the engine in question has variable cam timing.

Ignition timing has nothing to do with it. Compression is about the volume of the cylinder and how much the gases in it are squeezed. When they are ignited, or indeed if they are ignited at all, is immaterial.
Understand what you're saying and thanks for the explanation.

Maybe if instead of "effectively" I said it makes the engine "sort of act like" it has a lower compression ratio
__________________
E82 Non-Sport / Ver Red / Blk Boston L / BMWP Springs w/ Koni Yellows / M front control arms / AT / Sport seats & steering wheel + paddles / HK / Nav
Appreciate 0
      06-15-2018, 12:16 PM   #12
desertman123
E82 Mudflap Ambassador
desertman123's Avatar
United_States
1287
Rep
1,537
Posts

Drives: '08 128i
Join Date: May 2016
Location: Orlando, FL

iTrader: (0)

Garage List
2008 BMW 128i  [5.00]
2014 BMW 528i  [5.00]
Quote:
Originally Posted by MightyMouseTech View Post
Uh, you can't change the compression ratio.

As for OP, it won't make the slightest difference except removing cash from your wallet.
Tell that to Infiniti.

Also just advance your ignition timing until you hear knock, then back it off 1

Last edited by desertman123; 06-15-2018 at 12:24 PM.
Appreciate 0
      06-15-2018, 12:44 PM   #13
The Wind Breezes
Lieutenant Colonel
The Wind Breezes's Avatar
614
Rep
1,578
Posts

Drives: 135i N55 DCT
Join Date: Apr 2015
Location: USA

iTrader: (0)

Long story short you would need to tune the car to see even marginal gains. The ECU won't make more power with race fuel thru "adaptation" it's tuned so conservatively it won't even take full advantage of 93 octane...though not like there's much on the table there lol. Also, use a real race fuel like VP or sunoco if you want high octane but don't run leaded it will foul your cat fast and your o2 sensors a little more slowly. Also, you bought the wrong car if you want to go fast (or more likely, your PARENTS did), because the N54 / N55 135 are now a dime a dozen, not really any more maintenance intensive than the N52 especially in the case of the N55 and they make tons more power both stock and with a easy reflash. Just saying, since you brought up this idea of wanting to go faster by means of a pretty ghetto method.

Quote:
Originally Posted by desertman123 View Post
Also just advance your ignition timing until you hear knock, then back it off 1
Something I'm sure the OP will get right to doing, lol.
Appreciate 1
      06-15-2018, 02:56 PM   #14
MightyMouseTech
Brigadier General
MightyMouseTech's Avatar
2975
Rep
4,967
Posts

Drives: 13 135i 6MT LeMans Blue MSport
Join Date: Feb 2013
Location: Ottawa, Canada

iTrader: (0)

Quote:
Originally Posted by desertman123 View Post
Quote:
Originally Posted by MightyMouseTech View Post
Uh, you can't change the compression ratio.

As for OP, it won't make the slightest difference except removing cash from your wallet.
Tell that to Infiniti.

Also just advance your ignition timing until you hear knock, then back it off 1°
Well, SAAB did it first.
Appreciate 1
Post Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


All times are GMT -4. The time now is 12:12 PM.




1addicts
Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST