Go Back   Jeep Garage - Jeep Forum > Jeep Platform Discussion > Grand Cherokee - WK2 - > Trouble Shooting/Problems/Service

Join Jeep Garage Today
Reply
 
Thread Tools Display Modes
 
  #25  
Old 03-29-2014, 02:31 PM
Premium Member
My Jeep: 2014 5.7L WK2
 
Join Date: Oct 2013
Location: Bay Village, OH
Posts: 791
Thanks: 10
Thanked 47 Times in 44 Posts
Rep Power: 1400
14SummitHemi has a reputation beyond repute14SummitHemi has a reputation beyond repute14SummitHemi has a reputation beyond repute14SummitHemi has a reputation beyond repute14SummitHemi has a reputation beyond repute14SummitHemi has a reputation beyond repute14SummitHemi has a reputation beyond repute14SummitHemi has a reputation beyond repute14SummitHemi has a reputation beyond repute
Re: Summit - V8 Hemi - Fuel choice

I hate everytime 2014RedHemiGC posts cuz he reminds me he has a badass livery!

2014 Jeep GC Limited 4X4 V8 QD2
2012 Cadillac CTS-V Coupe
2011 Chevy Corvette Z06/07
__________________

__________________
Reply With Quote
The Following User Says Thank You to 14SummitHemi For This Useful Post:
  #26  
Old 03-29-2014, 06:58 PM
BobsWK2's Avatar
Premium Member
 
Join Date: Aug 2010
Posts: 1,529
Thanks: 3
Thanked 23 Times in 21 Posts
Rep Power: 49570
BobsWK2 has a reputation beyond reputeBobsWK2 has a reputation beyond reputeBobsWK2 has a reputation beyond reputeBobsWK2 has a reputation beyond reputeBobsWK2 has a reputation beyond reputeBobsWK2 has a reputation beyond reputeBobsWK2 has a reputation beyond reputeBobsWK2 has a reputation beyond reputeBobsWK2 has a reputation beyond reputeBobsWK2 has a reputation beyond reputeBobsWK2 has a reputation beyond repute
Re: Summit - V8 Hemi - Fuel choice

I bet even when the WK2 is at the end of the assembly at JNAP, they just put regular 87 octane fuel in whether its a V6 or V8.
__________________

__________________
2014 Summit 4X4, V8
Reply With Quote
  #27  
Old 03-30-2014, 09:23 AM
Member
My Jeep: 2012 5.7L WK2
 
Join Date: Nov 2011
Location: perry hall, maryland
Posts: 420
Thanks: 0
Thanked 3 Times in 3 Posts
Rep Power: 1648
peckmv has a reputation beyond reputepeckmv has a reputation beyond reputepeckmv has a reputation beyond reputepeckmv has a reputation beyond reputepeckmv has a reputation beyond reputepeckmv has a reputation beyond reputepeckmv has a reputation beyond reputepeckmv has a reputation beyond repute
Re: Summit - V8 Hemi - Fuel choice

Octane has nothing to do with gas mileage. It is nothing but an anti-knock agent. The higher octane allows the computer to advance the timing and to eliminate ping and increase performance. The increased octane will slow the fuel-air mixture from firing in a high compression engine. Carbon buildup on the pistons can also cause "ping". Higher octane is used in higher compression engines because 87 octane can pre-ignite before the spark plug fires and this causes the "ping". The link provides more info.....

Is High Octane Gas Worth the Money? | Wanderings
__________________
Reply With Quote
  #28  
Old 03-30-2014, 08:33 PM
Member
 
Join Date: Jan 2014
Location: Tulsa area
Posts: 179
Thanks: 0
Thanked 3 Times in 3 Posts
Rep Power: 2060
Rexlion has a reputation beyond reputeRexlion has a reputation beyond reputeRexlion has a reputation beyond reputeRexlion has a reputation beyond reputeRexlion has a reputation beyond reputeRexlion has a reputation beyond reputeRexlion has a reputation beyond reputeRexlion has a reputation beyond reputeRexlion has a reputation beyond reputeRexlion has a reputation beyond reputeRexlion has a reputation beyond repute
Re: Summit - V8 Hemi - Fuel choice

But you say it can improve performance. Well, increased fuel economy is one possible byproduct of improved performance, right?

The article you link to says:
"One exception is with engines or cars designed for high octane gas. In that case, using high octane gas WILL improve performance and mileage. The reason has to do with the compression and ignition timing characteristics of the engine. Those specially designed engines will only perform efficiently with higher octane gas. Most engines are not designed this way."

The question this raises is: has the Hemi in its current configuration been designed for higher octane gas? Since the manual recommends mid-grade, the answer might be yes. It might perform more efficiently on mid-grade, which would equate to a combination of better acceleration and/or better mpg's.

I think that from the sound of most comments, the improvement on mid-grade is probably a rather small one, though.
__________________
Reply With Quote
  #29  
Old 03-31-2014, 05:43 AM
Member
My Jeep: 2012 5.7L WK2
 
Join Date: Nov 2011
Location: perry hall, maryland
Posts: 420
Thanks: 0
Thanked 3 Times in 3 Posts
Rep Power: 1648
peckmv has a reputation beyond reputepeckmv has a reputation beyond reputepeckmv has a reputation beyond reputepeckmv has a reputation beyond reputepeckmv has a reputation beyond reputepeckmv has a reputation beyond reputepeckmv has a reputation beyond reputepeckmv has a reputation beyond repute
Re: Summit - V8 Hemi - Fuel choice

Quote:
Originally Posted by Rexlion View Post
But you say it can improve performance. Well, increased fuel economy is one possible byproduct of improved performance, right?

The article you link to says:
"One exception is with engines or cars designed for high octane gas. In that case, using high octane gas WILL improve performance and mileage. The reason has to do with the compression and ignition timing characteristics of the engine. Those specially designed engines will only perform efficiently with higher octane gas. Most engines are not designed this way."

The question this raises is: has the Hemi in its current configuration been designed for higher octane gas? Since the manual recommends mid-grade, the answer might be yes. It might perform more efficiently on mid-grade, which would equate to a combination of better acceleration and/or better mpg's.

I think that from the sound of most comments, the improvement on mid-grade is probably a rather small one, though.
What you say is true. What I was saying is that octane by itself does nothing for mileage but it does increase performance in engines that are designed for higher octane. What I mean by performance is that due to a more efficent burn the engine performs better than if you run 87 octane. The increase in mileage, if any, would be because you would be running the correct fuel and less predenotation which results in an engine being more fuel efficent. If you run 89 in an engine designed for 87 then your performance and mileage would not change. I have run both in mine and have found no increase or decrease in mileage. I do notice better performance with 89. It costs a little over $2 per tankfull more, so the cost is small.
__________________

__________________
Reply With Quote
Reply

Thread Tools
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 Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Best fuel for 87 Tune? 87 pure or 89 w/ ethanol - Jeep Hemi TyBauz Engine Performance/Intake/Exhaust 5 03-04-2013 10:16 PM
2009 5.7L Hemi - Suggestions for Better Fuel Economy?? mlsmith3344 Engine Performance/Intake/Exhaust 11 04-09-2012 12:07 AM
Hemi Fuel Economy Comparison After Mods. jeepgcoman Grand Cherokee - WK 0 05-06-2011 03:11 PM
Fuel economy 5.7 hemi DanD2124 Grand Cherokee - WK 48 05-06-2011 02:00 AM

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 02:10 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Copyright 2012 - JeepGarage.Org
The Jeep Grand Cherokee Owners Community