Go Back   EcoModder Forum > EcoModding > General Efficiency Discussion
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 02-09-2011, 07:57 PM   #91 (permalink)
NightKnight
 
NachtRitter's Avatar
 
Join Date: Dec 2008
Location: Placerville, CA
Posts: 1,594

RippinRoo - '05 Subaru Legacy Wagon 2.5 GT
Subaru
90 day: 21.16 mpg (US)

Helga - '00 Volkswagen Jetta TDI
TEAM VW AUDI Group
Diesel
90 day: 53.91 mpg (US)

Olga - '03 Volkswagen Jetta Wagon
90 day: 46.24 mpg (US)
Thanks: 303
Thanked 310 Times in 186 Posts
Quote:
Originally Posted by Old Tele man View Post
...from that same source:

"Knock and preignition are both favoured by high temperatures, so one may lead to the other. Under high-speed conditions knock can lead to preignition, which then accelerates engine destruction
[27,28]."


...bold emphasis is mine, not the author.
Correct... knock can lead to preignition. Knock is not the same as preignition.

Thanks for clarifiying.

  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 02-09-2011, 09:03 PM   #92 (permalink)
Confused, as usual
 
Join Date: Feb 2011
Location: SW Michigan
Posts: 13
Thanks: 2
Thanked 0 Times in 0 Posts
Well, I read the whole thing. I'd say you were spot on Mr. NachtRitter. Thanks for the link and re recommending it after I skipped over it the first time.

Octane rating is not related to when a fuel preignites or auto ignites (per se), it's actually measuring the probability of molecules being broken down into other molecules that are more likely to auto ignite.

it takes more heat to auto ignite diesel fuel than gasoline, however diesel fuel either A) breaks down into readily auto ignited compounds easier/faster than gasoline when exposed to high heat and pressure or B) breaks down into compounds that are more auto ignitable than what gasoline breaks down into.

It makes sense now. I think a lot of the confusion here was many terms that were being used in a less than 100% accurate manner.

If you go on to read further, it does state that it does not hurt to use lower octane fuel in a vehicle than what is specified if the vehicle does not knock (although a knock sensor would prevent you from knowing this). High elevation and low temperatures also allow the use of lower octane. If the vehicle is not knocking, then lowering the octane is no problem.

If you can advance your timing with the same octane you used before, you decreased your margin for error and reap the rewards of better mileage & torque. Buying lower octane for cheaper saves $, and causes no harm if it isn't making the vehicle knock. So diesel lowering the octane rating isn't necessarily bad.
  Reply With Quote
Old 02-09-2011, 09:15 PM   #93 (permalink)
Confused, as usual
 
Join Date: Feb 2011
Location: SW Michigan
Posts: 13
Thanks: 2
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by UFO View Post
Oh very good. And how is my statement "The engine was designed for gasoline - use it." an opinion?
Most vehicles we not designed to have the tops chopped or boat tails attached, but people still do it. It's your opinion that everyone should use gasoline in the cars designed for gasoline.

Quote:
Originally Posted by UFO View Post
Come on now, what sort of benefit is expected or documented? Diesel reduces the octane, so you will now knock when you compress this brew, so you either damage your engine or your ECM reduces timing for poor mileage.
I don't know if there is any expected result, but you cannot document results without testing/experimenting, it's one of those "cause and affect things". If one were to try and and document poor fuel economy or no gain, then it's knowledge gained.

Quote:
Originally Posted by UFO View Post
This forum usually sticks to sound experimentation looking for effective ways to reduce petroleum consumption, but this thread is almost as far into the weeds as HHO. Sorry to have to be the one to point it out, but now the rest is up to you.
What classifies sound and unsound experimentation?
  Reply With Quote
Old 02-09-2011, 09:39 PM   #94 (permalink)
NightKnight
 
NachtRitter's Avatar
 
Join Date: Dec 2008
Location: Placerville, CA
Posts: 1,594

RippinRoo - '05 Subaru Legacy Wagon 2.5 GT
Subaru
90 day: 21.16 mpg (US)

Helga - '00 Volkswagen Jetta TDI
TEAM VW AUDI Group
Diesel
90 day: 53.91 mpg (US)

Olga - '03 Volkswagen Jetta Wagon
90 day: 46.24 mpg (US)
Thanks: 303
Thanked 310 Times in 186 Posts
Quote:
Originally Posted by FourBinLabs View Post
Well, I read the whole thing. I'd say you were spot on Mr. NachtRitter. Thanks for the link and re recommending it after I skipped over it the first time.

Octane rating is not related to when a fuel preignites or auto ignites (per se), it's actually measuring the probability of molecules being broken down into other molecules that are more likely to auto ignite.

it takes more heat to auto ignite diesel fuel than gasoline, however diesel fuel either A) breaks down into readily auto ignited compounds easier/faster than gasoline when exposed to high heat and pressure or B) breaks down into compounds that are more auto ignitable than what gasoline breaks down into.

It makes sense now. I think a lot of the confusion here was many terms that were being used in a less than 100% accurate manner.

If you go on to read further, it does state that it does not hurt to use lower octane fuel in a vehicle than what is specified if the vehicle does not knock (although a knock sensor would prevent you from knowing this). High elevation and low temperatures also allow the use of lower octane. If the vehicle is not knocking, then lowering the octane is no problem.

If you can advance your timing with the same octane you used before, you decreased your margin for error and reap the rewards of better mileage & torque. Buying lower octane for cheaper saves $, and causes no harm if it isn't making the vehicle knock. So diesel lowering the octane rating isn't necessarily bad.
Good summary.... and I definitely agree that the terms are often not being used correctly.

Back to the original discussion...
  Reply With Quote
Old 02-09-2011, 09:54 PM   #95 (permalink)
UFO
Master EcoModder
 
UFO's Avatar
 
Join Date: Sep 2010
Location: Denver, CO
Posts: 1,300

Colorado - '17 Chevrolet Colorado 4x4 LT
90 day: 23.07 mpg (US)
Thanks: 315
Thanked 178 Times in 138 Posts
Quote:
Originally Posted by FourBinLabs View Post
Most vehicles we not designed to have the tops chopped or boat tails attached, but people still do it. It's your opinion that everyone should use gasoline in the cars designed for gasoline.
That analogy doesn't make sense. Let's stick to engines.

Quote:
Originally Posted by FourBinLabs View Post
I don't know if there is any expected result, but you cannot document results without testing/experimenting, it's one of those "cause and affect things". If one were to try and and document poor fuel economy or no gain, then it's knowledge gained.
I'll let you re-invent the wheel. I already know what happens when I reduce the octane of my fuel.

Quote:
Originally Posted by FourBinLabs View Post
What classifies sound and unsound experimentation?
Maybe you should read a few more threads, and judge for yourself.
__________________
I'm not coasting, I'm shifting slowly.
  Reply With Quote
Old 02-09-2011, 11:20 PM   #96 (permalink)
Confused, as usual
 
Join Date: Feb 2011
Location: SW Michigan
Posts: 13
Thanks: 2
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by UFO View Post
That analogy doesn't make sense. Let's stick to engines.
I fail to see how it does not apply. Making modifications to your vehicle is somehow more or less justifiable depending on what part you are working on? Just replace adding a boat tail with advancing the timing if that helps you understand.

Quote:
Originally Posted by UFO View Post
I'll let you re-invent the wheel. I already know what happens when I reduce the octane of my fuel.
I'm sorry to hear you have those kind of problems with your vehicle.

Quote:
Originally Posted by UFO View Post
Maybe you should read a few more threads, and judge for yourself.
I plan to do just that.
  Reply With Quote
Old 02-10-2011, 02:29 PM   #97 (permalink)
EcoModding Apprentice
 
tim3058's Avatar
 
Join Date: Sep 2009
Location: Northeast
Posts: 147

Silver Bullet - '86 Chevy Camaro Z28
90 day: 19.74 mpg (US)

New Blue - '96 Chevrolet Camaro Z28
90 day: 20.46 mpg (US)

Diesel - '96 Chevrolet Tahoe LS
Last 3: 13.56 mpg (US)

Tahoe #2 - '95 Chevrolet Tahoe LS
90 day: 13.05 mpg (US)

SuperDuty - '08 Ford F-350 dually Lariat
90 day: 9.34 mpg (US)

Fundai - '09 Hyundai Elantra
90 day: 26.45 mpg (US)

HRV - '17 Honda HRV LX
90 day: 31.39 mpg (US)
Thanks: 7
Thanked 18 Times in 12 Posts
Quote:
Originally Posted by UFO View Post
That analogy doesn't make sense. Let's stick to engines... I'll let you re-invent the wheel. I already know what happens when I reduce the octane of my fuel. ...Maybe you should read a few more threads, and judge for yourself.
Let's be open minded please.

The OP has a gas/EFI van and is running 30% diesel and reporting a noticeable 10-20% mpg boost. Worth looking into. I'm struck by the genius involved in such an out-of-the-box concept. Many questions surround how much is ok, and what long-term effects may be, but this might have potential for the serious experimental-type of ecomodder.

Good idea lindsayjim!

Any thoughts on what this would do in a lean-burn Honda VX engine?
__________________


  Reply With Quote
Old 02-10-2011, 05:08 PM   #98 (permalink)
...beats walking...
 
Join Date: Jul 2009
Location: .
Posts: 6,191
Thanks: 179
Thanked 1,521 Times in 1,122 Posts
...is the OP remembering to "include" the quantity of diesel fuel being added into the gasoline in his "total" fuel used calculations?

...ironically, both gasoline and diesel fuel both have the same stoichiometric A/F (by weight) combustion ratios -- 14.7-to-1 -- although rather differing energy content values:

gasoline = 114,000 BTU/gal
..diesel = 129,500 BTU/gal
  Reply With Quote
The Following User Says Thank You to gone-ot For This Useful Post:
FourBinLabs (02-11-2011)
Old 02-10-2011, 09:04 PM   #99 (permalink)
Confused, as usual
 
Join Date: Feb 2011
Location: SW Michigan
Posts: 13
Thanks: 2
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by tim3058 View Post
Many questions surround how much is ok, and what long-term effects may be, but this might have potential for the serious experimental-type of ecomodder.

Any thoughts on what this would do in a lean-burn Honda VX engine?
My guess is that a lean-burn situation would increase the chance of running into engine knock. It would seem that whatever affect you see most gasoline engines, you would see on a lean burn. This is purely speculation though. I've already learned from this thread that there is a lot more to what happens in the combustion chamber then meets the eye.

Also, just to let you know, I started a test on this back on Tuesday. I am running ~10% mix in my vehicle. I put in 2.5 gallons of diesel and 22 gallons of gasoline. I would have gone to 22.5 but ran out of room in the tank. Then again, I'm sure there was more than .5 gallons of gasoline in the tank, so maybe that's a good thing.

If someone secretly put 10% diesel into my tank, I would have no idea. Power seems unaffected, or has changed in such a small way that I can not tell. There is no change in exhaust look or odor.

I haven't been putting many miles on this week, and I have been letting my vehicle idle more than usual because of the recent cold temps. I am driving round trip to chicago this weekend (over 100mi each way), so I'll be able to get a good idea what the highway mileage is.

The bad news, I haven't been checking my mileage in this vehicle for a couple years because I only drive it in the winter. After running through a few tanks and switching back to gasoline, I can show some results. It's just going to take a long time.
  Reply With Quote
Old 02-10-2011, 09:22 PM   #100 (permalink)
EcoModding Apprentice
 
tim3058's Avatar
 
Join Date: Sep 2009
Location: Northeast
Posts: 147

Silver Bullet - '86 Chevy Camaro Z28
90 day: 19.74 mpg (US)

New Blue - '96 Chevrolet Camaro Z28
90 day: 20.46 mpg (US)

Diesel - '96 Chevrolet Tahoe LS
Last 3: 13.56 mpg (US)

Tahoe #2 - '95 Chevrolet Tahoe LS
90 day: 13.05 mpg (US)

SuperDuty - '08 Ford F-350 dually Lariat
90 day: 9.34 mpg (US)

Fundai - '09 Hyundai Elantra
90 day: 26.45 mpg (US)

HRV - '17 Honda HRV LX
90 day: 31.39 mpg (US)
Thanks: 7
Thanked 18 Times in 12 Posts
Cool, I'm looking forward to hearing what you discover FourBinlabs. Increased chance of knock was the only thing that I could come up with right offhand too, but I'd think the ECM should pull back the timing to compensate. Any of the chemical engineers/combustion experts care to theorize on mixing in diesel for lean-burn engines? Same effect as in lindsayjim's van or no?

__________________


  Reply With Quote
Reply  Post New Thread


Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Canceling out pumping losses of throttle governed engines greasemonkee EcoModding Central 60 08-03-2009 04:24 PM
Gasoline expected to remain cheap this summer Frank Lee The Lounge 0 04-14-2009 03:43 PM
Adding Acetone as an additive to gasoline - worthwhile? havok95z71 General Efficiency Discussion 14 01-18-2009 11:29 PM
As I Had Thought Big Dave General Efficiency Discussion 54 09-02-2008 11:00 PM
News: Shell rationing gasoline, diesel in Western Canada AndrewJ The Lounge 4 02-14-2008 08:26 PM



Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com