U.S. CitiesCity-Data Forum Index
Go Back   City-Data Forum > General Forums > Automotive > Brand-specific forums > Honda and Acura
 [Register]
Please register to participate in our discussions with 2 million other members - it's free and quick! Some forums can only be seen by registered members. After you create your account, you'll be able to customize options and access all our 15,000 new posts/day with fewer ads.
View detailed profile (Advanced) or search
site with Google Custom Search

Search Forums  (Advanced)
Reply Start New Thread
 
Old 07-07-2011, 06:53 AM
 
3,673 posts, read 4,931,180 times
Reputation: 2422

Advertisements

i know that the manual calls for premium....but how much does it matter?
I know a family member who bought a 2006 MDX brand new and never put anything but regular in it.....car has about 45k miles now and runs perfectly fine.

thanks for your thoughts.
Reply With Quote Quick reply to this message

 
Old 07-07-2011, 07:01 AM
 
34,355 posts, read 41,427,648 times
Reputation: 29840
Putting in regular probably wont hurt the engine as its computer will adjust engine parameters to compensate however there will be a slight decrease in power as the computer adjusts the timing.
The obvious question would be why would you buy an expensive sport sedan then cheap out on the gas,the difference between what the manufacturer recommends and the lower octane fuel is only going to be a couple of bucks per tank..
There are better options if you want an economy car..
Reply With Quote Quick reply to this message
 
Old 07-07-2011, 07:06 AM
 
3,129 posts, read 5,306,196 times
Reputation: 1588
....If the manual says PREMIUM why put in regular? to hurt performance and MPG? Any gas you think you save will end up costing you as it hurts those two areas.

Also depending on how much you drive, you might save a whopping $200 a year.
Reply With Quote Quick reply to this message
 
Old 07-07-2011, 07:18 AM
 
3,673 posts, read 4,931,180 times
Reputation: 2422
i understand the logic of "expensive car.....cheaping out on gas".....
BUT, my concern is that putting premium won't buy you anything extra aside from extra power.....
with 280 hp, i could lose a few and not car. i mean, really, i don't even need the 280 to begin with (it's nice....but losing 10 or 15 hp won't be noticeable to me)

Now, if MPG is reduced, then that's something that would come into the equation........by how much? .1 MPG reduced? or 5 MPG reduced?

i feel like (based on what i'm reading on various forums), that people don't seem to really know for sure. they've "heard" about loss of power and loss of MPG....but i haven't been able to find a study or paper to support any of this. (i hope there is some out there....and if you know a link, please post it).
you're right, $200 a year isn't much.....but if there's no good reason (apparently) to spend it, why should i?

(would you give me 200 bucks if i simply ask for it? Why not? it's only a 'whopping' 200 bucks! and i won't ask for any more for at least another year! :-)
Reply With Quote Quick reply to this message
 
Old 07-07-2011, 07:35 AM
 
Location: Poway, CA
2,698 posts, read 9,939,390 times
Reputation: 2229
As long as the knock sensor can pull enough timing to compensate, you'll be fine. However, if it can't, you'll be exposed to the wonderful world of pre-detonation, burnt valves, and all the other fun stuff that comes along with running crap gas in a higher-compression engine. Unless you're already completely familiar with the basics of an internal combustion engine, gasoline octane, and how the two correlate, I would suggest reading up on it. Not only will you come to understand why putting lower octane fuel in a car that requires it is bad, you'll also learn why putting higher octane in a car that doesn't require it makes no sense, either.

I'd agree that spending that kind of money on a vehicle seems rather pointless if you have no intention of following through on the basics. And aren't you the one who started a thread on whether a warranty on an Acura is worth it? Put it this way: if you ever have problems with the car related to the damages associated by running lower octane, you won't have any leg to stand on when they deny the warranty claim.

Mike
Reply With Quote Quick reply to this message
 
Old 07-07-2011, 07:44 AM
 
3,673 posts, read 4,931,180 times
Reputation: 2422
Quote:
Originally Posted by whiteboyslo View Post
As long as the knock sensor can pull enough timing to compensate, you'll be fine. However, if it can't, you'll be exposed to the wonderful world of pre-detonation, burnt valves, and all the other fun stuff that comes along with running crap gas in a higher-compression engine. Unless you're already completely familiar with the basics of an internal combustion engine, gasoline octane, and how the two correlate, I would suggest reading up on it. Not only will you come to understand why putting lower octane fuel in a car that requires it is bad, you'll also learn why putting higher octane in a car that doesn't require it makes no sense, either.

I'd agree that spending that kind of money on a vehicle seems rather pointless if you have no intention of following through on the basics. And aren't you the one who started a thread on whether a warranty on an Acura is worth it? Put it this way: if you ever have problems with the car related to the damages associated by running lower octane, you won't have any leg to stand on when they deny the warranty claim.

Mike
Thanks for the feedback. i appreciate it.
Reply With Quote Quick reply to this message
 
Old 07-07-2011, 07:50 AM
 
14,780 posts, read 35,977,311 times
Reputation: 14356
To get real basic there are two factors that go into producing power and determining what gas is needed:

1. Compression ratio of the engine - This is how hard the engine compresses the air and fuel mix. The higher the compression, the more efficient the engine and the more power it produces.

2. Timing - Is the moment that the spark ignites the fuel mixture during the compression stroke. The more aggressive/advanced the timing the more efficient the engine and the more power it produces.

The enemy of both of these factors is knock. Knock is the premature detonation of the combustion mixture in the cylinder. If you advance the timing too far you get knock. If the engines compression ratio is too high you get knock.

The octane rating of gasoline basically shows how resistant it is to detonation or knock. The higher the number, the higher the compression ratio and more advanced the timing can be. Engines are designed to take advantage of a certain level of octane gasoline taking into account the compression ratio and desired timing.

What happens when you run lower octane? Well, you get knock. Not under every circumstance but definitely under acceleration. Knock can damage the engine, so the car needs to compensate and elminiate the knock. The compression ratio can't be changed, so the car falls back on two things to control the knock:

1. Reduce timing - By reducing/retarding the timing the car can control knock. Doing this generally doesn't reduce the MPG, but it does decrease power. How much is based on how much timing is pulled. It could be anything from 2 or 3 horespower to 15+.

2. Richen the fuel mixture - By adding more fuel, the car can regain control of the burn. Remember, fuel is mixed with air at a specific ratio to allow it to burn, more fuel "cools" the mixture and allows the car to stop the knock. Richening the mixture will not only reduce power, but it will also mean you are burning more fuel. How much again depends on the amount of knock. The car can only add so much fuel and you will have reduced MPG.

In general a car will first richen the fuel mixture to contol the knock and only when that doesn't work will it begin to pull timing. It is all car dependent but most people who run regular in a car that requires premium will end up running rich under most circumstances and then have the car pull timing under hard acceleration. Neither condition is great long term.

So, the short answer would be, you will lose MPG all around and you will lose power under moderate to hard acceleration. How much is entirely dependent on the car. In some cars it is very noticable where there is a big difference in power and a 1 or 2 MPG difference, in others it is very slight. Overall, it really isn't worth running regular in a car that needs premium unless you have no other choice.
Reply With Quote Quick reply to this message
 
Old 07-07-2011, 07:52 AM
 
Location: WI
3,823 posts, read 8,915,943 times
Reputation: 2258
we've owned cars that required premium, and knew about it ahead of time so it wasn't an issue. We didnt like it a few years back when both our rides at the time needed it and it was over $4 per gallon back home, but the extra 20-25 cents per gallon was worth piece of mind instead of trusting the computer to adjust for any knocking. That knocking ( if it happens ) can have the same effect of hitting a piston with a hammer.... not good long term...

Even now in our s2000, it's set up for premium only and that's all we run. But I still get 28mpg out of a toy, so dont mind the bit extra for the right fuel. We didnt buy this car not to be able to take full advantage of everything under that hood.
Reply With Quote Quick reply to this message
 
Old 07-07-2011, 07:59 AM
 
3,673 posts, read 4,931,180 times
Reputation: 2422
Quote:
Originally Posted by NJGOAT View Post
To get real basic there are two factors that go into producing power and determining what gas is needed:

..........................

So, the short answer would be, you will lose MPG all around and you will lose power under moderate to hard acceleration. How much is entirely dependent on the car. In some cars it is very noticable where there is a big difference in power and a 1 or 2 MPG difference, in others it is very slight. Overall, it really isn't worth running regular in a car that needs premium unless you have no other choice.
Thanks very much! very informative! Much appreciate it.
i think i understand a bit better now....I think i'm going to run premium starting with the next tank......I use Costco, so the premium there is at the price of regular elsewhere....so i guess it'll be fine.

thanks again!
Reply With Quote Quick reply to this message
 
Old 07-07-2011, 08:56 AM
 
Location: Chicago
38,690 posts, read 89,161,233 times
Reputation: 29446
It's also worth noting that in order for a car's computer to dial back the timing and/or enrich the fuel mixture to prevent knocking, it has to have detected it in the first place -- in other words, knocking has already taken place and the computer is compensating to ensure it doesn't keep happening. But, it's already happened.

If your car calls for premium, use it.
Reply With Quote Quick reply to this message
Please register to post and access all features of our very popular forum. It is free and quick. Over $68,000 in prizes has already been given out to active posters on our forum. Additional giveaways are planned.

Detailed information about all U.S. cities, counties, and zip codes on our site: City-data.com.


Reply
Please update this thread with any new information or opinions. This open thread is still read by thousands of people, so we encourage all additional points of view.

Quick Reply
Message:


Over $104,000 in prizes was already given out to active posters on our forum and additional giveaways are planned!

Go Back   City-Data Forum > General Forums > Automotive > Brand-specific forums > Honda and Acura
Follow City-Data.com founder on our Forum or

All times are GMT -6.

2005-2019, Advameg, Inc. · Please obey Forum Rules · Terms of Use and Privacy Policy · Bug Bounty

City-Data.com - Archive 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35 - Top