ADVrider

Go Back   ADVrider > Riding > The perfect line and other riding myths
User Name
Password
Register Inmates Photos Site Rules Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
Old 06-27-2013, 05:25 AM   #46
foxtrapper
Studly Adventurer
 
Joined: Sep 2011
Oddometer: 614
Quote:
Originally Posted by Trespasser View Post
...how much...is left over from the last dude's 87 octane fillup, which is left in the hose, [and] gets pushed into your tank?
About 1/3 a gallon, according to API.

If you're really worried, try only filling up when the tank is as close to completely empty as possible, to minimize the dilution. And try to follow a hotrodish car from the pump, as they are more likely to have been refueling using a higher octane gasoline. That way the left over gas in the hose is higher octane.
foxtrapper is offline   Reply With Quote
Old 06-27-2013, 06:50 AM   #47
JimVonBaden
"Cool" Aid!
 
JimVonBaden's Avatar
 
Joined: Feb 2005
Location: Alexandria, VA
Oddometer: 48,170
Quote:
Originally Posted by jar944 View Post
for me:
my car- 93/94 (ran 87 until 93 proved cheaper/mile)
her car -87
street bike - 87
4t dirt bikes 93/94 (some of mine run great on 87, some detonate on 91 so its easier to have one can of 93/94)
2t dirt bikes 93/94 (det on lower grades)
cr500 50/50 93/110LL (detonates badly on straight 93/94)
Keep in mind I was referring to the BMW R1200 only because I am experienced in it and it has knock sensors.

Other vehicles vary. I use regular in my Sky Turbo in winter, but premium in summer to prevent detonation. I use only regular in my Nissan Roge because it doesn't need premium. It is all a judgement call, and what you are comfortable and what performs best in your vehicle.

Jim
JimVonBaden is offline   Reply With Quote
Old 06-27-2013, 07:09 AM   #48
Offcamber
Beastly Adventurer
 
Offcamber's Avatar
 
Joined: Aug 2010
Location: New Hampshire
Oddometer: 1,546
If the vehicle manufacturer requires premium ( high compression engine)...I put it in. (the S10 takes premium) if it doesn't then regular goes in....no reason to put high octane fuel in a vehicle that doesn't require it. If its knocking bad with regular and that's what it calls for you have other problems and your just masking the symptoms of a bigger problem.

Its your money and vehicle...so run what makes ya happy.
__________________
"Beer cans explode with a nice loud pop when they are hit by a Heidenau K60 at 40 miles an hour. Now my bike smells like last call..." Me

Offcamber screwed with this post 06-27-2013 at 07:35 AM
Offcamber is offline   Reply With Quote
Old 06-27-2013, 07:16 AM   #49
LittleRedToyota
Yinzer
 
LittleRedToyota's Avatar
 
Joined: Apr 2011
Location: Pittsburgh
Oddometer: 2,063
Quote:
Originally Posted by viverrid View Post
You probably are avoiding it. The pump blends from the tanks to make Mid-grade, but if there are separate hoses, each hose only ever gets its own grade in it
that's what i thought. thanks for the confirmation.
LittleRedToyota is offline   Reply With Quote
Old 06-27-2013, 08:03 AM   #50
Dan-M
Studly Adventurer
 
Dan-M's Avatar
 
Joined: Aug 2007
Location: Steger, IL
Oddometer: 754
Quote:
Originally Posted by JimVonBaden View Post
Unless you drive them hard it should work the other way around. The higher octane gas just prevents pinging in high performance motors.

http://mn.gov/commerce/weights-and-m...ctaneFacts.pdf

Jim
Actually modern high compression engines with knock sensors will ramp up the ignition timing as far as possible until knock (ping) is detected. Lower grade fuel will mean retarted timing resulting less power & mpg.

Even driven "gently" knock will occur with high compression. You may not hear it before the knock sensor does but it will effect mpg at steady cruise.
__________________
---

Dan-M screwed with this post 06-27-2013 at 08:11 AM
Dan-M is offline   Reply With Quote
Old 06-27-2013, 08:13 AM   #51
JimVonBaden
"Cool" Aid!
 
JimVonBaden's Avatar
 
Joined: Feb 2005
Location: Alexandria, VA
Oddometer: 48,170
Quote:
Originally Posted by Dan-M View Post
Actually modern high compression engines with knock sensors will ramp up the ignition timing as far as possible until knock (ping) is detected. Lower grade fuel will mean retarted timing resulting less power & mpg.
Actually, in most cases, modern motors will stay at max needed ignition timing until pinging occurs, then back the timing off to compensate. The distinction being that when a car is driven normally the car is at maximum economy. This means that if you are putzing around town, or cruising the freeway under normal circumstances, the car will not normally need premium. Exceptions being high performance cars and bikes with high compression motors.

Jim
JimVonBaden is offline   Reply With Quote
Old 06-27-2013, 08:29 AM   #52
Dan-M
Studly Adventurer
 
Dan-M's Avatar
 
Joined: Aug 2007
Location: Steger, IL
Oddometer: 754
Quote:
Originally Posted by JimVonBaden View Post
Actually, in most cases, modern motors will stay at max needed ignition timing until pinging occurs, then back the timing off to compensate. The distinction being that when a car is driven normally the car is at maximum economy. This means that if you are putzing around town, or cruising the freeway under normal circumstances, the car will not normally need premium. Exceptions being high performance cars and bikes with high compression motors.

Jim
Agreed Jim. The post you originally replied to concerning this issue was about the poster's high performance cars. (post 18)

As an aside, more and more modern engines comparitvely high compression.
Car makers are dealing with it in many ways but if premium is specified by the manufacturer, it will matter in most any driving scenerio.
__________________
---
Dan-M is offline   Reply With Quote
Old 06-27-2013, 08:47 AM   #53
ragtoplvr
Beastly Adventurer
 
Joined: Oct 2007
Location: S. W. Mssouri
Oddometer: 5,517
Quote:
Originally Posted by Dan-M View Post
Actually modern high compression engines with knock sensors will ramp up the ignition timing as far as possible until knock (ping) is detected. Lower grade fuel will mean retarted timing resulting less power & mpg.

Even driven "gently" knock will occur with high compression. You may not hear it before the knock sensor does but it will effect mpg at steady cruise.
Most cars have a map that sets the maximum ignition timing, and the lack of a knock will not allow the ignition timing to exceed the map. Actually you are not timing for no knock, you are timing for max efficiency, they do not necessarily coincide. The modern high swirl designs burn very fast, it is possible to burn without knock, and finish the burn before starting the down stroke, and loose efficiency. This is why max timing is set by the map, and knock sensor can retard it from there. Octane does not measure burn speed, it is just the resistance to knock. They are related, but it is not a 1 to 1 ratio.
ragtoplvr is offline   Reply With Quote
Old 06-27-2013, 08:50 AM   #54
randyo
Beastly Adventurer
 
randyo's Avatar
 
Joined: Nov 2007
Location: Northern NewEngland
Oddometer: 1,440
Quote:
Originally Posted by rapidoxidationman View Post
The capacity of a 100-foot length of 1-inch diameter hose is 4 gallons.
How much line is between the nozzle and the pump's switching valve?
fuel pump hose is generally 3/4" ID or 0.0073 gallons per foot

1/3 gallons residual is a very high estimate, more likely getting less than 0.2 gallons of residual
__________________
RandyO
IBA # 9560
07 VeeStrom
99 SV650
82 XV920R
A man with a gun is a citizen
A man without a gun is a subject
randyo is offline   Reply With Quote
Old 06-27-2013, 06:23 PM   #55
VonHelm
soggy doggy
 
VonHelm's Avatar
 
Joined: Oct 2007
Location: Grapevine, TX
Oddometer: 3,964
Quote:
Originally Posted by Benesesso View Post
Definitely the boobies. Would sure help my piston. Go for it!
so... how'd that work out for him?
__________________
http://www.oilandpiston.com/
Well he’s one of those who knows that life
Is just a leap of faith
Spread your arms and hold you breath
And always trust your cape (Guy Clark)
VonHelm is offline   Reply With Quote
Old 06-28-2013, 10:47 AM   #56
corndog67
Banned
 
Joined: Jan 2006
Location: Santa Maria, CA
Oddometer: 1,281
My XR650L with a high compression piston would ping pretty good on regular, a little less on 89 , and a little less on 91. Still detonated though. I've got a 6.2 GM with 402 HP, that dials back the timing, hence the power and fuel mileage on 87, definitely runs stronger on 91 though. My 950 SM also pings on regular, so I run 91 in it. Some of the wives tales I hear about octane are incredible.
corndog67 is offline   Reply With Quote
Old 06-28-2013, 01:32 PM   #57
RTLover
Beastly Adventurer
 
RTLover's Avatar
 
Joined: Nov 2009
Location: West-central France
Oddometer: 3,300
When I bought my R12RT, the sales guy told me to run premium as a habit but it would run on just about anything flammable in a pinch. Hell, with premium costing nearly 8 dollars a gallon (equivalent after figuring the euro rate of exchange) and regular about 50 cents less, it really doesn't matter.
__________________
R1200RT
RTLover is offline   Reply With Quote
Old 06-28-2013, 03:24 PM   #58
przjohn
Adventurer
 
Joined: Aug 2008
Location: Ellington, CT
Oddometer: 75
None of this will be relevant once my refinery is up and running. Octane ratings will become meaningless as my fuel will fit the bill for all!!!!!!!!!
przjohn is offline   Reply With Quote
Old 06-28-2013, 07:28 PM   #59
Benduro OP
I<3CrayCrayVaJayJay
 
Benduro's Avatar
 
Joined: Jul 2012
Location: El Portal, Ca
Oddometer: 1,347
Quote:
Originally Posted by foxtrapper View Post
About 1/3 a gallon, according to API.

If you're really worried, try only filling up when the tank is as close to completely empty as possible, to minimize the dilution. And try to follow a hotrodish car from the pump, as they are more likely to have been refueling using a higher octane gasoline. That way the left over gas in the hose is higher octane.
I'm not worried about it, as I don't run premium in my bike, and my car is a turbo-diesel. Just an academic question that struck me the other day, and in typical fashion, asking it here has increased my understanding.
__________________
"The world is a hellish place, and bad writing is destroying the quality of our suffering." - Tom Waits
Benduro is online now   Reply With Quote
Old 06-29-2013, 02:56 PM   #60
Frostback
Frostback
 
Joined: Sep 2007
Location: Edmonton, Alberta
Oddometer: 216
I think Foxtrapper nailed it. Go to a busy station and fall in behind any Audi, Beemer, Porsche, or Cadillac. The hose will contain their residual high octane for you.

I used to inherit the dregs of the 5 gallon transport jugs of 100 octane leaded fuel aviation gas from our fleet of airboats. It made my old SR500 just sing but I didn't use it often to prevent lead fouling.

Lee
Frostback is offline   Reply With Quote
Reply

Share

Thread Tools Search this Thread
Search this Thread:

.
Display Modes

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 On

Forum Jump


Times are GMT -7.   It's 12:25 AM.


Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright ADVrider 2011-2014