Gas
#21
quick starts and highway passing etc. 40-60 sprints etc. one of those is going to suffer.
Its like tire pressure. Tires are designed to for multiple cars. So tire inflation guidelines are for NVH
#22
Yes and no.
Spark ignites, begins process ignition, fuel burns. Fuel burns a variable rates and btu's. The longer a fuel burns (typically) the more energy it gives off. Then throw in the things we use to cOntrol IGNITION, when the fuel ignites.
That's all we control. Hotter spark makes for a better ignition, that's it. It does not cOntrol the rate at which fuel burns. The fuel we use dictates the amount of time it burns compounded by compression and air flow or swirl which can also dictate the flame travel after ignition.
Spark ignites, begins process ignition, fuel burns. Fuel burns a variable rates and btu's. The longer a fuel burns (typically) the more energy it gives off. Then throw in the things we use to cOntrol IGNITION, when the fuel ignites.
That's all we control. Hotter spark makes for a better ignition, that's it. It does not cOntrol the rate at which fuel burns. The fuel we use dictates the amount of time it burns compounded by compression and air flow or swirl which can also dictate the flame travel after ignition.
The OP is discussing the types of fuel to use.
Our computers get more energy out of higher octane fuel.
Lower octane fuel won't let our motors produce as much well rounded power response and emissions.
The manufaturers want the mOtor to produce 100% of its capability.
Our computers get more energy out of higher octane fuel.
Lower octane fuel won't let our motors produce as much well rounded power response and emissions.
The manufaturers want the mOtor to produce 100% of its capability.
Now add to that that some 3.9's are actually a lower compression ratio and do not require premium fuel, they are 8.35:1 instead of the higher 9.35:1 that all other Land Rovers are with the 3.9-4.0 engines.
Using my Ultra-Gauge I ran a 2 tanks of regular in my truck keeping track of my MPG, I lost 1-1.5 MPG by the end of the 2nd tank of fuel.
Keeping a eye on timing is a PIA because it changes with every hill that I go up or down, as well as other factors, like the wind blowing, if I'm drafting a semi or that same GD Prius is drafting me, intake air temp, etc.
If you want to go cheap on fuel thats your buisness, personally I'll go cheap on wiper blades and spend the extra $3 per week to fill my truck with the REQUIRED octane rating fuel.
And thank you for the correction on the TDC and BTDC.
Is there anyway I can run regular unleaded in my disco using octane boost (some stations around here tend to run out of premium quite often) or is it just best to stick with Premium.
Also my dad says I could fill up with regular gas and then throw a bottle of rubbing alcohol and it does the same thing as a octane booster.
Also my dad says I could fill up with regular gas and then throw a bottle of rubbing alcohol and it does the same thing as a octane booster.
Oh, and my Disco passes emissions with flying colors each year running low octane. I'll step away from the keyboard now.
#23
I ask these question using the average 1997 4 liter automatice with cats and 9.25 compression.
Help me with these questions. You seem to have lots of knowledge.
What do our knock sensors do, what do they control, how do they work?
How does air density (hot air and cold air) effect combustion, timing with high octane and low octane fuels.
Do higher octane fuels have more BTU's per gallon?
Do higher octane fuels enhance early or late combustion?
Does diesel fuel have more BTU's than Gasoline? How do we take advantage of it?
does more initial ignition advance produce a peppier car at a stop light?
Does more ignition advance allow for a cooler engine?
Does super unleaded fuel contain more fuel additives then low octane fuel from the same maker such as techron?
Help me with these questions. You seem to have lots of knowledge.
What do our knock sensors do, what do they control, how do they work?
How does air density (hot air and cold air) effect combustion, timing with high octane and low octane fuels.
Do higher octane fuels have more BTU's per gallon?
Do higher octane fuels enhance early or late combustion?
Does diesel fuel have more BTU's than Gasoline? How do we take advantage of it?
does more initial ignition advance produce a peppier car at a stop light?
Does more ignition advance allow for a cooler engine?
Does super unleaded fuel contain more fuel additives then low octane fuel from the same maker such as techron?
#24
Join Date: May 2009
Location: North Carolina Coast
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First off octane is an actual chemical part of gas, octane rating is the gases ability to resist detonation compared to a known sample of gas. A gas that has low octane can have its octane rating raised by adding different compounds, the most common is ethanol. So you can have a 93 octane rated gas that actually has no more octane than an 87. That's why I hate the 10% mixed gas you are getting less "power" aka octane, I'm sure I'm not the only one who noticed a drop in my mpg when they started putting ethanol in the gas.
#25
First off octane is an actual chemical part of gas, octane rating is the gases ability to resist detonation compared to a known sample of gas. A gas that has low octane can have its octane rating raised by adding different compounds, the most common is ethanol. So you can have a 93 octane rated gas that actually has no more octane than an 87. That's why I hate the 10% mixed gas you are getting less "power" aka octane, I'm sure I'm not the only one who noticed a drop in my mpg when they started putting ethanol in the gas.
#26
Join Date: May 2009
Location: North Carolina Coast
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Just read in the rave, the knock sensor can sense if any cylinder is knocking aka preignition, when it senses knock it retards that cylinders timing then advances it to find the optimum timing for it and according to all the other inputs like tps, vss, maf. So I would assume that the higher octane you could put in the more the computer could addvance your timing giving you more power and efficientcy. Of coarse this doesn't apply to distributor models without knock sensors.
#27
Just read in the rave, the knock sensor can sense if any cylinder is knocking aka preignition, when it senses knock it retards that cylinders timing then advances it to find the optimum timing for it and according to all the other inputs like tps, vss, maf. So I would assume that the higher octane you could put in the more the computer could addvance your timing giving you more power and efficientcy. Of coarse this doesn't apply to distributor models without knock sensors.
Bingo! Thus...to a certain extent typically more timing will produce more efficient combustion more power and economy. Doing less with more while maintaining the use of cats (ie getting them hot enough to produce the chemical reaction)
My bet is that we see less ignition advance on out ultra gauges in the summer plus we see less power.
#28
Yes there was a low compression 3.9, very few were imported to the NAS market.
Here are the compression ratios for all of the Rover engines.
http://jimsrover.afraid.org/rover/gt...troduction.pdf
Here are the compression ratios for all of the Rover engines.
http://jimsrover.afraid.org/rover/gt...troduction.pdf
#29
For background and more discussion, there is a tune select resistor that is used in various markets, depending on fuel quality and CAT requirements (CAT or no CAT).
From RAVE:
White wire, 3K9 Ohms, European catalyst
It is on C243 of the ECU. Most likely sets range of advance. Mercedes had a similar one, dash mounted, on Euro models, a selector switch you turned depending on quality of fuel you could purchase.
Here's a link to a write up of the GEMS system used on the Morgans, very similar to ours. http://www.gomog.com/allmorgan/GEMS/GEMSbyPoole.pdf
attached is a LR document set on types of fuel injection systems used
here's a link to the LR booklet on the Bosch engine management, has good write up on the way the various sensors operate and impact fuel economy, etc. http://www.google.com/url?sa=t&rct=j...hBObmeBccwHDUw
And then there is the book by Des Hammill that contains piles of data and pix of Rover engines with an attitude... http://books.google.com/books?id=gmS...page&q&f=false
From RAVE:
To suit individual market requirements a tune select
resistor is connected across pins 5 and 27 of the
ECM.
It is located adjacent to the ECM, and strapped to the
MFI cable assembly. The value of the resistor is
dependent on the market application:
Red wire, 180 ohms, Australia, Rest of world.
Green wire, 470 Ohms, UK and Europe - non catalyst.
Yellow wire 910 Ohms, Saudi non catalyst.
resistor is connected across pins 5 and 27 of the
ECM.
It is located adjacent to the ECM, and strapped to the
MFI cable assembly. The value of the resistor is
dependent on the market application:
Red wire, 180 ohms, Australia, Rest of world.
Green wire, 470 Ohms, UK and Europe - non catalyst.
Yellow wire 910 Ohms, Saudi non catalyst.
White wire, 3K9 Ohms, European catalyst
It is on C243 of the ECU. Most likely sets range of advance. Mercedes had a similar one, dash mounted, on Euro models, a selector switch you turned depending on quality of fuel you could purchase.
Here's a link to a write up of the GEMS system used on the Morgans, very similar to ours. http://www.gomog.com/allmorgan/GEMS/GEMSbyPoole.pdf
attached is a LR document set on types of fuel injection systems used
here's a link to the LR booklet on the Bosch engine management, has good write up on the way the various sensors operate and impact fuel economy, etc. http://www.google.com/url?sa=t&rct=j...hBObmeBccwHDUw
And then there is the book by Des Hammill that contains piles of data and pix of Rover engines with an attitude... http://books.google.com/books?id=gmS...page&q&f=false
Last edited by Savannah Buzz; 12-04-2011 at 10:42 PM.
#30
I ask these question using the average 1997 4 liter automatice with cats and 9.25 compression.
Help me with these questions. You seem to have lots of knowledge.
What do our knock sensors do, what do they control, how do they work?
How does air density (hot air and cold air) effect combustion, timing with high octane and low octane fuels.
Do higher octane fuels have more BTU's per gallon?
Do higher octane fuels enhance early or late combustion?
Does diesel fuel have more BTU's than Gasoline? How do we take advantage of it?
does more initial ignition advance produce a peppier car at a stop light?
Does more ignition advance allow for a cooler engine?
Does super unleaded fuel contain more fuel additives then low octane fuel from the same maker such as techron?
Help me with these questions. You seem to have lots of knowledge.
What do our knock sensors do, what do they control, how do they work?
How does air density (hot air and cold air) effect combustion, timing with high octane and low octane fuels.
Do higher octane fuels have more BTU's per gallon?
Do higher octane fuels enhance early or late combustion?
Does diesel fuel have more BTU's than Gasoline? How do we take advantage of it?
does more initial ignition advance produce a peppier car at a stop light?
Does more ignition advance allow for a cooler engine?
Does super unleaded fuel contain more fuel additives then low octane fuel from the same maker such as techron?