Car Forums  

Go Back   Car Forums > Technical Discussions > Repairs & Maintenance
FAQ Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
Old 01-23-2004, 12:14 AM   #16
VrrmPshh
CF Newbie
 
Join Date: Jan 2004
Location: CA
Posts: 12
gasoline is pretty harsh on rubber too though so im not worried about it....
VrrmPshh is offline   Reply With Quote
Old 01-23-2004, 06:13 AM   #17
vwhobo
CF's Anal Orifice
 
vwhobo's Avatar
 
Join Date: Feb 2003
Location: Redneck Hell
Posts: 8,630
Running toulene for an octane boost is nothing new, my father was doing it in the '50's in his '49 Merc lead sled.

If we're going to do something stupid and dangerous, why don't we go all the way. Let's run xylene (117) as an octane booster, after all it has an even higher octane number than toulene (114). Of course some of the short and long term effects of having either in your fuel system are rotted fuel lines, damaged injectors they can even decompose your plastic gas tank. And if you run them in high enough concentrations you'll damage your catalytic converter(s) and your oxygen sensor(s). Cheap parts to replace I'm sure you'll agree.

Better yet, I can get you a really good deal on some MTBE (118). Any takers?
__________________
Thanks for the pic, jedimario.

"Everybody believes in something and everybody, by virtue of the fact that they believe in something, use that something to support their own existence."
Frank Vincent Zappa, 1940-1993

vwhobo is offline   Reply With Quote
Old 01-23-2004, 07:43 AM   #18
asa67_stang
CF Enthusiast
 
asa67_stang's Avatar
 
Join Date: Nov 2003
Location: the eighth circle of hell in Maryland
Posts: 240
actually, there's a guy at FSP (my inline six forum that i hang at) that flirted briefly with all of those...
notice i said briefly, he knew what it could do to the various parts, he just wanted to see what he could get away with without pinging
__________________
I love going fast.... it's the crashing and burning that sucks

i wish i knew now what i will know in thirty years, that would be nice...

the 'net has warped my fragile little mind
asa67_stang is offline   Reply With Quote
Old 03-01-2005, 11:35 PM   #19
Logicalbomb
CF Newbie
 
Join Date: Mar 2005
Posts: 1
I run 116 octane in my car, and it works just fine, I don't get whats so stupid about it, as a matter of fact, if I don't run it diluted with a premium, my car gets minor detanation, and runs lean, my RPM will increase by about 400, and my intake sounds like it's a vacuum. Of course if you don't have a car that will handle the fuel properly, and you think you're some kind of racer when you aren't, don't run it, because it will harm your engine, I designed my engine specifically to run at a higher compression.
Logicalbomb is offline   Reply With Quote
Old 03-01-2005, 11:49 PM   #20
windsonian
Dodger65's weirdo
 
windsonian's Avatar
 
Join Date: Jan 2005
Location: Down Below
Posts: 2,081
Octane basically says how much compression it can handle without knocking. In "high performance" engines, the compression ratio is higher, so low octane fuels won't be very good as you might get spontaneous combustion (ie explosion without the spark).
windsonian is offline   Reply With Quote
Old 03-02-2005, 12:19 AM   #21
srober32
CF Addict
 
srober32's Avatar
 
Join Date: Feb 2005
Location: Detroit, Michigan
Posts: 442
As silly as it sounds, octane ratings are about how slow the fuel burns. I think, but don't quote me on this, that 91 octane under x pressure at y volume takes 91 milliseconds to combust. 100 octane would take 100 milliseconds under the same conditions and so on and so forth. For most street cars produced in the U.S. they are set to run on like 87 or 89 octane and too much more than that is indeed a waste of money. As for adding chemicals to increase octane ratings, be very careful and remember that all of the previous batch has not been run out.
__________________
When replacing your altenator, make sure your battery is fully charged.
srober32 is offline   Reply With Quote
Old 05-03-2005, 12:56 AM   #22
lithiumdeuterid
CF Newbie
 
Join Date: May 2005
Posts: 1
Octane rating is a measure of the "anti-knock" properties of gasoline, and doesn't have much to do with combustion speed. It is not measured in milliseconds, either. Consider what would happen if you used 98 octane gasoline in an engine with huge pistons (many liters per piston). Would this gasoline combust in the same amount of time as 98 octane gasoline in a normal cylinder (0.5 liters)? Obviously not. The flame front would move at a similar speed, but because of the greater size, the combustion would take longer to complete in the larger engine.

Here is the real story, and the first eight hydrocarbon names:

1 Methane
2 Ethane
3 Propane
4 Butane
5 Pentane
6 Hexane
7 Heptane
8 Octane

.....CH3..H..CH3
......|...|...|
CH3---C---C---C---CH3 <-- Iso-octane
......|...|...|
.....CH3..H...H


Iso-octane, otherwise known as (2,2,4-trimethylpentane) is very smooth-burning, and is assigned an anti-knock rating of 100. Heptane, on the other hand, is very susceptible to knock, and is assigned a rating of 0. The gasoline you buy at the pump is rated on a scale from heptane to iso-octane. An octane rating of 93 means the gasoline has the same anti-knock rating as a mixture of 93% octane and 7% heptane. An octane rating greater than 100 indicates that the fuel is even less susceptible to knock than pure iso-octane.

You can see a sticker at the pump that says "calculated using the (R+M)/2 method". The R is the Research Octane Number, from an engine running at 600 RPM. The M is the Motor Octane Number, from an engine running at 900 RPM. The two are averaged to provide the total octane number you see at the pump.

I hope this dispels some of the myths floating around.

Last edited by lithiumdeuterid : 05-03-2005 at 01:04 AM.
lithiumdeuterid is offline   Reply With Quote
Old 12-03-2005, 08:44 PM   #23
vwhobo
CF's Anal Orifice
 
vwhobo's Avatar
 
Join Date: Feb 2003
Location: Redneck Hell
Posts: 8,630
Well it sure shut the thread down. I guess now Satty will come along and lock it.
__________________
Thanks for the pic, jedimario.

"Everybody believes in something and everybody, by virtue of the fact that they believe in something, use that something to support their own existence."
Frank Vincent Zappa, 1940-1993

vwhobo is offline   Reply With Quote
Old 12-03-2005, 10:01 PM   #24
newyorker
MXman
 
newyorker's Avatar
 
Join Date: Nov 2005
Location: Philly
Posts: 5,291
I heard that higher octane burns either faster or with more temperature and can help clean the valves.
newyorker is offline   Reply With Quote
Old 12-03-2005, 10:04 PM   #25
vwhobo
CF's Anal Orifice
 
vwhobo's Avatar
 
Join Date: Feb 2003
Location: Redneck Hell
Posts: 8,630
Quote:
Originally Posted by newyorker
I heard that higher octane burns either faster or with more temperature and can help clean the valves.
Once again you heard wrong. What a surprise. All you had to do was read the thread and at least one of those is covered.
__________________
Thanks for the pic, jedimario.

"Everybody believes in something and everybody, by virtue of the fact that they believe in something, use that something to support their own existence."
Frank Vincent Zappa, 1940-1993

vwhobo is offline   Reply With Quote
Old 12-03-2005, 11:42 PM   #26
vwhobo
CF's Anal Orifice
 
vwhobo's Avatar
 
Join Date: Feb 2003
Location: Redneck Hell
Posts: 8,630
Quote:
Originally Posted by tbaxleyjr
Good discussion. key point is IF the engine is not knocking, there is no difference in the energy output between 87 and 93 octane fuels since there is no significant difference in the higher heating value (energy released during combustion) between the two fuels.
Better do some reading on that subject. There are plenty of research articles the confirm that running gasoline with an octane rating higher than required actually decreases power output.
__________________
Thanks for the pic, jedimario.

"Everybody believes in something and everybody, by virtue of the fact that they believe in something, use that something to support their own existence."
Frank Vincent Zappa, 1940-1993

vwhobo is offline   Reply With Quote
Old 12-04-2005, 02:17 AM   #27
electrodes
CF Newbie
 
Join Date: Nov 2005
Location: Hillsboro, Oregon
Posts: 7
Fuels...

In a completely stock car you are better off switching from the cheap stuff to the premium fuel if you are selling it. If someone is test driving it and puts the pedal on the floor it is less likely to rattle if something doesn't go just right and you might only have the one chance on a test drive.

If you run high blower, or turbo boost, or have a performance chip and find that your car preignites at high load use higher octane gas or ethanol
(if you can get it). If you raise the compression above the stock compression ratio then you will need higher octane gas or ethanol if it preignites under load. Check your base ignition timing as well as your advance curve before stepping up at the pump. Additives cause crappy deposits. If you are worried about rubber seals then step up to Viton as it is easy to get and holds up to gas additives and ethanol both (sometimes better than aluminum).

Octane is strange, as is the Cetane rating of diesel. Research the BTU ratings if you switch fuel types. Ethanol doesn't preignite in the real world and you can always add more but the lower BTU means you need to fatten it up (nearly 40%) to get the same amount of power. To get even more power with ethanol you can run much more compression and boost, then watch your oil turn green. It shouldn't cost as much to run ethanol as 116 octane gasoline.

If the 100 octane mentioned is blue then suspect it is a low-lead aviation fuel and don't run cats or you will cook them.

I have a diesel car I run with biodiesel and regular diesel. The cetane is about the same in each but the BTU in the biodiesel means much worse mileage and it costs more. Used to pitcrew for alcohol dragsters and can not wait until that stuff is available on the street. Nice complex topic...
electrodes is offline   Reply With Quote
Old 12-04-2005, 04:27 AM   #28
Wally
I Know More Than You
 
Wally's Avatar
 
Join Date: May 2004
Location: Oz
Posts: 2,564
Too many guys no too little about cars
__________________
"She gave me a look only a mother could give a child."

Last edited by Wally : 12-04-2005 at 04:32 AM.
Wally is offline   Reply With Quote
Old 12-04-2005, 07:30 AM   #29
Sick88Tbird
Master of the Fox-chassis
 
Sick88Tbird's Avatar
 
Join Date: May 2004
Location: Sicklerville, NJ
Posts: 578
Quote:
Originally Posted by vwhobo
Better do some reading on that subject. There are plenty of research articles the confirm that running gasoline with an octane rating higher than required actually decreases power output.

You're 110% correct on that. I usually run on 87 octane in my T-bird with 16* base timing and about 38* total...from what everyone else says they've experienced, I shouldn't be able to do that without some detonation...probably because I'm not running the E7TE heads, but rather the larger chambered E6SE heads. It runs slightly better on Sunoco 94 at the track.

Just a few months ago, I went to Atco Raceway and ended up making twice as many runs as I had planned...leaving me in a slight fuel crisis, didn't think I could make it home on what I had. I went to the pumps and the lowest octane I could find was like 104...I bought $30 worth...about 5.25 gallons, just to get me home. After that, the car ran like absolute sh!t, started surging real bad at idle and didn't want to make power. After about 5-6 fill-ups of 87, it was back to normal. Car still surges slightly...but that's due to needing a new TPS sensor.
__________________
New Toy- Stone stock '88 T-bird Sport in need of some TLC

1988 Cougar XR-7- HO/T-5 conversion, cracked block prevented from reaching full potential.

RIP '88 T-Bird....14.1@98.7mph...best sleeper in So. Jersey, now it's taking a permanent dirt nap.
Sick88Tbird is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Turbo question General Chat 5 07-07-2005 10:18 PM
Got a newbie to preludes question? Asian Imports 3 12-28-2004 02:05 AM
Another newb question! Morphias87 General Chat 22 02-20-2004 03:10 PM
Gear's question. vishal8u General Chat 2 03-05-2003 04:28 AM
noob question rx-7_4th generation General Chat 1 12-07-2002 07:15 AM



All times are GMT +1. The time now is 06:57 PM.

Powered by vBulletin Version 3.5.4
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Copyright © 2002 - 2011 Car Forums. All rights reserved.