Porsche Babblers  

Go Back   Porsche Babblers > Porsche Boxster and Cayman Forum > Boxster / Cayman

Boxster / Cayman Porsche Boxster and Cayman Forum - Topics and discussions about the Porsche Boxster and Cayman


Reply
 
Thread Tools
Old May 13th, 2008, 09:52 AM   #1
charvey
Junior Member
 
Join Date: May 2008
Posts: 5
gas grade

Its more than likely a foregone conclusion, but is it must to use premium gas in a 2002 Boxster?
charvey is offline   Reply With Quote
Old May 14th, 2008, 12:51 PM   #2
70Sixter
Senior Member
 
70Sixter's Avatar
 
Join Date: Nov 2006
Location: Surf City, NC
Posts: 147
What's premium at your location? 91 or 93? Since you cannot get 93 everywhere, cars must be able to use 91. I don't know what the performance benefit might be. Some engines benefit from the higher octane. It also might have more additives.

I would not use 89.
__________________
Mike
04 Boxster S 6spd Basalt/Savanna
70 914-6 Black 'n Tan
PCA since 1970

http://www.babblers.org/forums/vbgoo...597656&zoom=14
70Sixter is offline   Reply With Quote
Old May 14th, 2008, 03:32 PM   #3
charvey
Junior Member
 
Join Date: May 2008
Posts: 5
gas grade

Thank you for your reply. Is not using 89 octane a question of performance or will using it or something inbetween premium and regular or regular more a question of doing damage to the engine? I have been using 91 and 93 when I can get it. I have owned the car for a little less than 6,000 miles and it has ran great so far. The question I ask is of course somewhat brought on by the rapidly rising gas prices, especially in WV.
charvey is offline   Reply With Quote
Old May 15th, 2008, 10:17 AM   #4
ppbon
Senior Member
 
ppbon's Avatar
 
Join Date: Aug 2007
Location: Weston (Ft. Lauderdale), Florida
Posts: 467
The reason why the recommended gas in the Boxster is minimum 93 octane is because the car has a high compression ratio 11.3:1 IIRC.
Higher compression engines will prematurely detonate lower octane grades, causing pinging and knocking which can potentially damage the engine in the long-term.
The Boxster can compensate somewhat for the lower octanes, but you should use the highest octane you can find.
There is a minimal performance boost with the higher octanes. Try racing fuel one day (100+ octane) and you will see.
Happy Boxstering,
Pedro
__________________
Racecar spelled backwards is: RACECAR

Come visit: www.PedrosGarage.com
ppbon is offline   Reply With Quote
Old May 17th, 2008, 11:15 AM   #5
ColinC
Junior Member
 
Join Date: Apr 2008
Posts: 17
I use 91 premium (its what we have in the bay area) in my 02. No sense in risking your 10k engine to detonation to save 5c/gallon in gas

-C
ColinC is offline   Reply With Quote
Old May 18th, 2008, 09:06 AM   #6
RNajarian
Senior Member
 
Join Date: May 2005
Location: Southern California
Posts: 238
It is not as bad as you think

Actually if you do the math you will realize that the higher grade is not as expensive as you think

If there is a 20 cent difference between the 87 and 91 octane fuel and you are putting 15 gallons in you are only paying an extra $3.00.

Not too hard to stomach.
__________________
R Najarian
2005 Cayenne Titanium Metallic
2000 Boxster Artic Silver
1975 911 Targa Guards Red
1983 911 SC Guards Red (RIP)
RNajarian is offline   Reply With Quote
Old May 19th, 2008, 04:21 PM   #7
albaker
Junior Member
 
Join Date: Oct 2006
Posts: 10
Octane rating is the ability of a the fuel to avoid pre-ignition. The higher the rating the more resistance. Engine compression - the higher the compression ratio the higher the likelihood of pre ignition. Engine timing is set to get the spark to fire prior to the cylinder hitting top dead center such that the complete explosion occurs at the optimum time (each engine is different). The pinging that happens with the lower Octane gas is because it preignited (as Pedro stated). This is bad for the engine because it puts extra stress and wear on the critical engine parts. Porsche recommends 93 Octane but says 91 is acceptable. I agree, do not go below this to 89. The Porsche engine has sensors determine if/when predetonation occurs and compensates accordingly. I do not know what technique Porsche uses, but most either increase the fuel mixture or change the ignition timing. This can only compensate so much. It also reduces the engine preformance because it is now in a non optimal setting. I think that Pedro has it reversed. 100 Octane does not increase performance. If you had a car that was made for low Octane (low compression) you would see no effect with 100. What you see is the degradation of performance in the Porsche as it compensates for the lower octane fuel that is available to us.
albaker is offline   Reply With Quote
Old May 19th, 2008, 04:34 PM   #8
Docdanracy
Senior Member
 
Docdanracy's Avatar
 
Join Date: Dec 2003
Location: Auburn, CA
Posts: 1,282
I ran 87 in my '99 all the time unless I was on the track or at an AX.
Car did not run any rougher with the lower grade gas and never pinged (detonated)
the very complex computer programs and detonation sensors will always just back off the timing a bit and the car runs just fine.

you may have a slightly decreased level of perfomance, but it won't hurt the motor. The computer won't let it.
__________________
Dan
GGR AX and TT instructor for 20+ yrs.
Maintained by Me
Docdanracy is offline   Reply With Quote
Reply

  Porsche Babblers > Porsche Boxster and Cayman Forum > Boxster / Cayman



Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
What's this about Sunol grade getting a toll road?! *NM* Catalog Guy Boxster / Cayman 3 April 26th, 2003 08:59 PM
Next Doc Wong Driving Skills and Tour Clinic-Sunday April 27, 2003! Harry Wong Boxster / Cayman 1 April 1st, 2003 11:38 PM
Next Doc Wong Driving Skills and Tour Clinic-Saturday June 22, 2002! Harry Wong Boxster / Cayman 0 June 20th, 2002 12:22 PM
Next Doc Wong Driving Skills and Tour Clinic-Saturday May 18, 2002! Harry Wong Boxster / Cayman 0 May 14th, 2002 11:50 AM
BABBLERS "Maintenance Day" Magic Mtn Dan Boxster / Cayman 9 July 11th, 2001 10:49 AM

Google+


Copyright © 2001-2014 Babblers. All rights reserved.
Babblers is a Porsche Boxster and Cayman enthusiast's forum, but it is in no way affiliated with, nor does it represent Porsche of Stuttgart, Germany.