what grade gasoline

[robm]

just curious out there what grade gasoline everyone is using with tv while pulling camper

[fast murray]

My gas pickup ran fine with 87 octane regular unleaded. The sell 85 octane in western SD which I tried once in an effort to not use ethanol but it's too low. I've been told there's no benefit to running higher octane gas than what the compression ratio of your engine dictates. For me that was 87 octane, now it's diesel.

[force]

87 in everything (truck, car, motorcycle, lawn mower, weed whacker, chainsaw, snowmobiles...). Everything but the car & truck (and the bike in summer) get Stabil with every tank.

[raspivey]

Originally Posted by fast murray

I've been told there's no benefit to running higher octane gas than what the compression ratio of your engine dictates.

Mostly correct. It's only real benefit is to prevent detonation. The higher the compression and / or the more load on the engine, the higher the chance of detonation. Towing would put more stress on the motor, so there's probably a valid argument for moving to higher octane while doing so, but it just depends on the vehicle, load, and terrain.

I run 87 in everything but the Camaro (the computer doesn't like anything but premium). The bike gets mid grade since I push it a little harder and I'll use mid grade while I'm towing, even though it might not matter either way.

[TURBS]

Higher the octane the better the fuel mileage.
The increase in fuel mileage pays for the difference in cost.

TURBS

Sabre owners united!

[cpaulsen]

I run 87 all the time except towing then I swap to 89 for my SCT tow tune.

[Dennis and Julie]

Always run 91 in everything we own, don't like how things run with ethanol and boat dealer said ethanol not recommended. My owners manual for my pick up says the same.

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[beerjay]

Originally Posted by f1100turbo

Higher the octane the better the fuel mileage.
The increase in fuel mileage pays for the difference in cost.

TURBS

Sabre owners united!

A CBC consumer show did an independent test of gas types last year and televised the results for various vehicles.

They used test gear for mileage and emissions as well as mechanical inspections. The high octane produced worse gas mileage and created more emissions than the regular gas. This is because the computers in the vehicle are set for a specific octane that is specified in the user manual. In some cases they noted worse performance on the road with the high octane since the computer was not set for it.

Some performance cars require higher octane but that will be specified in the user manual.

I think in the days of coils and mechanical carbs higher octane could be usefull.

Higher octane myths are fueled <g> by gas stations and gas companies since it costs the consumer a lot more.

[Deeks]

91 or higher, truck has a tune that's made for higher octane.

Trailer Fuel station and generator i run non ethanol

[RPAspey]

Originally Posted by f1100turbo

Higher the octane the better the fuel mileage.
The increase in fuel mileage pays for the difference in cost.

TURBS

Sabre owners united!

I run 89 normally as I found that I get about 1.5 mpg BETTER than when I use 87. So, at 23 gallons I'll get 34.5 miles more to tank. At 13-14 city mpg, that'll save me about 2 gallons at $3.79 or so for 89. At .17 a gallon more, that tank will cost me $3.91 more, but I'll SAVE a net of $3.67. And my Tundy seems to run smoother under load.

2000 Cherokee 31BH, "flipped axles and raised",LEDs, solar, inverter, etc..aka "boondock ready". '07 Tundra 5.7L DC-LB, modded as well.

[acadianbob]

Originally Posted by fast murray

I've been told there's no benefit to running higher octane gas than what the compression ratio of your engine dictates.

I don't think that this is so true anymore. In the quest for more power out of smaller displacement engines and better fuel economy, most modern engines have very high compression ratios. Ratios this high would have absolutely required high octane fuel to prevent detonation in the old days.

In today's world of variable cam timing and variable timing advance, one can use 87 octane in high compression engines. The ECM manages all of this with detonation sensors to get maximum performance for the fuel and load conditions.

So, there CAN be some benefit to higher octane fuels in many engines. This allows more advance; giving higher performance and economy. This is especially true in turbocharged or supercharged engines.

I've monitored the timing advance on my F150 with a ScanGaugeII. I can tell you that the ECM is constantly changing the timing. And when I tow, I can definitely tell the difference between 87 and 91 octane on the truck's ability to hold 6th gear on uphills. It runs fine on 87 and doesn't detonate. But there is a performance difference when running 91.

My turbocharged VW Jetta is definitely faster with 91 and gets about 10% better fuel economy. Why? On 87 it pulls a lot of timing to prevent detonation.

[John4th]

I have run higher grades in my Tundra, it made no difference in economy and power. Same for our CRV. Se we continue to run 87 in everything. I have not experienced any improvements in consecutive tanks of the premium stuff.

[MrJoe]

With today's electronic systems, the octane is dictated by the computer's setup (tune). If it's factory stock and the owners manual says 87, that's what to use. I have also seen worse mpg running higher octane.

[pappcam]

Originally Posted by MrJoe

With today's electronic systems, the octane is dictated by the computer's setup (tune). If it's factory stock and the owners manual says 87, that's what to use. I have also seen worse mpg running higher octane.

Exactly.

People who run high octane fuel when the vehicle or tune does not ask for it are just throwing away money.

[John4th]

Originally Posted by pappcam

Exactly.



People who run high octane fuel when the vehicle or tune does not ask for it are just throwing away money.

X2

[beerjay]

US Gov site on octane.

CBC Marketplace test on fuel.

However adding ethanol in regular gas muddies the water and the engine ... Not many retailers use a mix of ethanol in regular gas here.

[F and E Damp]

Modern (since maybe 2000) engine computers sense whether there's any knocking on lower octane fuels and adjust ignition and injector parameters appropriately. I get about 8 mpg on my MH and it doesn't seem to matter what grade I use, so I get the cheapest.

On less than 5000 miles in a typical season, the difference in cost vs. fuel burned wouldn't be visible. If I was full-timing and driving 20K a year, I'd do a more detailed study. Most of the time we fill up at Costco, Safeway or tribal gas stations, since they're usually 5 cents or more chaeaper than the big names.

[TURBS]

Originally Posted by beerjay

A CBC consumer show did an independent test of gas types last year and televised the results for various vehicles.

They used test gear for mileage and emissions as well as mechanical inspections. The high octane produced worse gas mileage and created more emissions than the regular gas. This is because the computers in the vehicle are set for a specific octane that is specified in the user manual. In some cases they noted worse performance on the road with the high octane since the computer was not set for it.

Some performance cars require higher octane but that will be specified in the user manual.

I think in the days of coils and mechanical carbs higher octane could be usefull.

Higher octane myths are fueled <g> by gas stations and gas companies since it costs the consumer a lot more.

This is false.

The computer adjusts according to "engine knock" to give the proper air fuel ratio and timing.
There "not set" to a pre determined octane ratio.
This is just silly.

TURBS

Sabre owners united!

[TURBS]

Originally Posted by acadianbob

I don't think that this is so true anymore. In the quest for more power out of smaller displacement engines and better fuel economy, most modern engines have very high compression ratios. Ratios this high would have absolutely required high octane fuel to prevent detonation in the old days.

In today's world of variable cam timing and variable timing advance, one can use 87 octane in high compression engines. The ECM manages all of this with detonation sensors to get maximum performance for the fuel and load conditions.

So, there CAN be some benefit to higher octane fuels in many engines. This allows more advance; giving higher performance and economy. This is especially true in turbocharged or supercharged engines.

I've monitored the timing advance on my F150 with a ScanGaugeII. I can tell you that the ECM is constantly changing the timing. And when I tow, I can definitely tell the difference between 87 and 91 octane on the truck's ability to hold 6th gear on uphills. It runs fine on 87 and doesn't detonate. But there is a performance difference when running 91.

My turbocharged VW Jetta is definitely faster with 91 and gets about 10% better fuel economy. Why? On 87 it pulls a lot of timing to prevent detonation.

You are correct!


TURBS

Sabre owners united!

[RhoZeta]

Always has been lots of misinformation on octane. People have always assumed higher octane means more power when in reality the higher the octane number the SLOWER the fuel burns so that pre-ignition does not occur before the spark plug fires. (Ala a diesel ignition) a car designed for 87 using higher octane cannot fully burn the fuel/air charge resulting in raw fuel going out the exhaust valve. using higher octane fuel than required is a waste of money and will eventually kill your catalytic converter due to unburnt fuel constantly being fed to it.

Don't believe me, look it up,all the info is out there.
All the anecdotal stories in the ether mean nothing next to the hard science.

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