Anyone know how much power is lost when using regular fuel vs premium in the 4.0 V6?

[ASE_Master-Tech]

Originally Posted by Snakeii

- Gee Mr Master Techabutor -
- As I previously stated "the majority" of ASE mechanics from my experinces are half wits. -
- So get off your box. -
- ASE certified or not. From my experience the majority are nothing more then a wannabe with a certificate. -
- I'm reducing the chances of having to rely on a "certified" tech touching my vehicle. They cant even do a oil change without fracking it up, why would I want them to try to troubleshoot a problem? -

*** Unfortunately I dont have a computer to plug the ECU into.???

If you were not being insulting & condesending, how would you describe all the quoted statements above?
I was not being condecending, your statement was ignorant (ie-without knowledge)
I think this thread has been hi-jacked long enough already, so if there are no more technical questions...


*** ps - Didn't you say you were a "computer tech"? Even me, a lowly "half wit" ASE tech, can hook up a laptop to scan, pull codes, & upload parameters to/from an ECU. That's right, just a plain old vanilla IBM laptop, & though I'd prefer a Linux O/S, M/Soft will do the job also (BTW-the interface, it's called a serial cable)

[Snakeii]

Defintion of OPINION:
A belief or conclusion held with confidence but not substantiated by positive knowledge or proof

I do have knowledge you imbecile. Perhaps if you took a step off your soap box and read my posts as a opinion (based on my personal experiences) you would get over it. If I made a opinion that Ford sucks, would you attack me in the same manner?

If you are now done masterbating, lets get this thread back on topic.

[mdbrjb]

A real comparison. They've done this with reg oil vs. synthetic so - Why not a chassis dino to show if there is any measured HP difference at the rear wheels between regular and premium? Someone must have done this.

My bet would be that premium would show a little gain in HP. But at $3.50 a gallon I don't think that permium would be worth it.

Also, there must be a limit on what the ECU can do regarding knock. Traveling, I've purchased low-grade gasoline that would knock if the engine was loaded too much at low rpms. (And this doesn't normally happen with "good" gasoline). Now the bad gas might have been lower than advertised octane, but it shows there is a limit to what the ECU can do.

[ASE_Master-Tech]

Originally Posted by mdbrjb

A real comparison. They've done this with reg oil vs. synthetic so - Why not a chassis dino to show if there is any measured HP difference at the rear wheels between regular and premium? Someone must have done this.

My bet would be that premium would show a little gain in HP. But at $3.50 a gallon I don't think that permium would be worth it.

Also, there must be a limit on what the ECU can do regarding knock. Traveling, I've purchased low-grade gasoline that would knock if the engine was loaded too much at low rpms. (And this doesn't normally happen with "good" gasoline). Now the bad gas might have been lower than advertised octane, but it shows there is a limit to what the ECU can do.

If you are referring to an "engine dyno", those readings are really subject to operator input. I've seen the same engine "dyno'ed" by one operator, with 10% different results 10mins later with another operator. It's very subjective.

Yes, you are correct, there are limits (parameters) that the ECU operates within. "Bad" gas would be below the 87 octane rating required by the manufacturer, & below the combustion specs set for the ECU. Problems would most certainly occur.

I believe that some of the confusion here relates to the fact that high performance/race vehicles (ie-high horsepower) require higher octane fuels so folks just naturally think it's the fuel that provides this extra power.

The fact is that engines in these types of vehicles (gasoline fueled that is) tend to have significantly more compression pressure so they squeeze more air/fuel into a smaller area & get a greater expansion effect, therefore more "power". The problem is that pressure & temperature are relative so when you raise the pressure, you raise the temperature. When you raise the temperature, you are more likely to "auto-ignite" the air/fuel mixture that is present, so a higher rated octane (which is simply a rating of a fuel blends ability to resist "auto-ignition" - not it's power value/BTU content) fuel is required to prevent this untimely detonation.

If you cannot raise the compression pressure in your engine, you will not benefit from the use of higher octane fuels.
Calling it "premium" is a marketing ploy & somewhat deceptive-IMHO.

[mdbrjb]

ASE_Master-Tech you have given one of the best explanations so far. I always figured that differences of less than 5% were probably within the range of error and therefore mean little.

Because older engines couldn't adjust (no ECU, or primitive ECU) you could tell a difference between octanes of gas. At least as far as ping was concerned. But I haven't noticed any difference in performance or mileage on my 2.7 with different octanes of gas. There might be conditions (like poor gasoline while trailer towing) where one could be near the limit of the ECU's ability to compensate but under normal operation it shouldn't make any difference.

Also, defending ASE techs. There are a few bad mechanics that give all mechanics a bad name. When we encounter a hack it makes us paranoid of all mechanics. This isn't fair. There are many very good ASE techs out there! Also, it's been my experience that there are bad dealers that don't support the advice of their mechanics and the customer suffers.

Thanks for the explanation.

[NitroPye]

My favorite kind of gasoline is the kind that makes my truck go vrrrrmmm. In fact I have never bought gas that didn't make it go vrrrrmmm.

Serious now, those were some good explanations on how engines and fuel work. I learned a bit from reading this thread. Thanks everybody.

[flyman767]

Here are my numbers: 4.0L Auto

20 Gallon Tank x 20(avg mpg) = 400 MILES (89 Octane)

20 Gallon Tank X 18.5(avg mpg) = 370 MILES (87 Octane)

Same exact driving, same brand of gas, same route(approx 60% highway, 40% city)

30 miles farther(89 octane) divided by 20 mpg = 1.5 gallons farther with 89 octane

1.5 gallons X $3.29 gallon = $4.93 (savings)

.10 gallon more (89 octane) = $2.00 (additional cost)

$4.93 - $2.00 = $2.93 savings per tank per fill-up.

Not a tremendous amount of savings; however, these aren't numbers for just 1 or 2 fill-up's; rather, these are the consistent numbers for each and every fill-up to date. Therefore, my conclusion running 89 vs 87: less overall cost, less carbon build-up, more MPG, more HP, slightly lower cruise rpm's. You can quote any mechanical theory you want, but the proof, as far as I'm concerned... is in the numbers.

[Snakeii]

Originally Posted by flyman767

Not a tremendous amount of savings; however, these aren't numbers for just 1 or 2 fill-up; rather, these are the consistent numbers for each and every fill-up to date. Therefore, my conclusion running 89 vs 87: less overall cost, less carbon build-up, more MPG, more HP, slightly lower cruise rpm's. You can quote any mechanical theory you want, but the proof, as far as I'm concerned... is in the numbers.

Thanks for sharing those numbers.

Unfortunately my trips to/from work, to lunch, etc are fairly sporadic so its hard to get the numbers locked down like that. With a mix of mostly highway, with a couple of side road trips (driving the same route to work gets old), a couple of off-road excursions my average is 17mpg. Perhaps I'll ease up on eating out for lunch so often, stop any unnecessary driving that could throw the numbers off and compare the octanes as well.