What Octane Grade Fuel for 3800 SC?

Unless that jet fuel is unleaded, I wouldn't do it.

Maybe Travis can explain how extra ethanol can increase KR? (I don't think it's the ethanol, I think it's the octane, or a problem not related to fuel quality).

I think you are talking about av gas.. not jet fuel. Jet fuel is basically karosene. Av gas is heavily leaded (more so than 110 race gas) so stay away from it.

yep...thats it ...AV gas....

is all AV gas leaded???

AA - I'm not sure, but on my way here to Montana I had to fill up with that stuff twice, and when I did my Riv knocked big time under acceleration....but when I filled her up with normal 91 oct, she ran just fine.....

it may take the pcm some time to change the fuel tables when you switch gas. give some drive time with the "new" gas before changing the tune.
just a thought.
i know my car acts funny when the weather changes dramatically either way. it takes a day or 2 for the car to take note of the change.

The problem is that under 'normal' driving, the PCM will eventually learn the fuel trims for your E20 gas. But for WOT, the only solution will be to increase your IFR table a small percentage. The problem is, I'm not sure what percentage you'll need to change it.

You should sue the state, gather up a nice class-action lawsuit, claiming they are forcing gas suppliers to provide inadequate fuel to operate your vehicle normally.

You can probably just increase your entire IFR table the same percentage, starting small, maybe 3% and see if your fuel trims settle down a little bit.

What kind of LTFTs are you seeing under 'normal' driving (cruise and idle)

To my knowledge all Av Gas is still leaded.
They call it LL (Low Lead) but it's too much for newer cars. Anything past the 70's.
We used to mix it with unleaded in our older V8's
To hell with the valves, just smoke the tires. But we also didn't have to worry about Cat Converter's either.

Av gas is very heavily leaded... I used to run it in my '64 Riv (still had the orig soft valve seats). In older cars, it was used because of the lubricating properties in the valve train. Now it would just cause massive problems. When I tore apart my 425 it was caked in blueish sludge from the 110LL. You will make the O2 sensor fail very quick too (that's what I did running 104 leaded race fuel prior to paint).

Chicken, you get anywhere with that E20?

Mark, can't you find any 91 NON-Oxy gas out there? It has no ethanol added. I can get 91 that has ethanol mixed, or straight 91. In Fargo the non-oxy formulation simply has no ethanol label on it. In Moorhead, the non-oxy has a label that it is ONLY for use in off-road, or older classic vehicles that need it. I can't get better than 91 here either, unless I want to pay big bucks for 102 unleaded. $8/gal.

I still don't understand how adding ethanol to gas would increase KR. It should only make you lose power. Travis, thoughts?

Right, that doesn't make sense. But Mark is running lower octane fuel than what he used before his move back to MT, right Mark? It's a lower octane fuel, but with the ethanol added, it's sold as 91 premium. Most of the 91 in Fargo is the same way, except that I can also find it non-oxy (ethanol free) in 91. Doesn't affect KR really, but I get better mileage from REAL gas.

If it's sold as 91, it should be rated exactly the same as a mixture of 91% iso-octane and 9% heptane. They can substitute different anti-knock ingredients, but the end result should be the same as the reference mixture. If it's not suppressing knock to the same degree as 91, then it's not 91. Instead it would be rated something lower, such as 89, 87, or worse.

My guess is, you filled up at a station with incorrect testing procedures, or bad gas. See if the problem continues. Don't use the same station again if you can help it.

I'm guessing there's KR because it's leaner than it should be, since fuel delivery needs to be increased as you increase the ratio of ethanol.

deekster_caddy wrote:

Chicken, you get anywhere with that E20?

Deek...not yet....I haven't had time to even do a proper scan yet....the house comes first....hopefully after the holidays I'll have time to dedicate my time to the riv again.....

1998 Riv wrote:

Mark, can't you find any 91 NON-Oxy gas out there? It has no ethanol added. I can get 91 that has ethanol mixed, or straight 91. In Fargo the non-oxy formulation simply has no ethanol label on it. In Moorhead, the non-oxy has a label that it is ONLY for use in off-road, or older classic vehicles that need it. I can't get better than 91 here either, unless I want to pay big bucks for 102 unleaded. $8/gal.

I haven't checked whats around me yet as far as other gas stations....My wife filled the Rivi up last with that ethenol shit and this town is so small its gonna take me a month to burn it off...

1998 Riv wrote:

Right, that doesn't make sense. But Mark is running lower octane fuel than what he used before his move back to MT, right Mark? It's a lower octane fuel, but with the ethanol added, it's sold as 91 premium. Most of the 91 in Fargo is the same way, except that I can also find it non-oxy (ethanol free) in 91. Doesn't affect KR really, but I get better mileage from REAL gas.

Right...in PA I was running 93 oct, here in MT I only see 91 oct, but I am at a higher altitude here....maybe thats the problem???

oh shit....I haven't calibrated my aeroforce gauge to this altitude...would that throw off the knock numbers on the gauge???

Chicken wrote:

Right...in PA I was running 93 oct, here in MT I only see 91 oct, but I am at a higher altitude here....maybe thats the problem???

At higher altitudes, the air is less dense, meaning there is less oxygen in your air/fuel mixture, so lower octane fuels are usually acceptable, w/o knock being a problem. In the Black Hills of SD, I've usually seen nothing higher than 89 available, and only 87 at some stations up there.

Quote :

I haven't calibrated my aeroforce gauge to this altitude...would that throw off the knock numbers on the gauge???

The altitude has no bearing on your KR readings. If your gauge says 13º, the mics are picking up the ping, so you are knocking that much. I've half surprised you aren't hearing it.

okay...thats it....I'm scanning this weekend.....

am i good to run 110 octane race gas? I want to but my buddy told me that i can't. I also have an intense pcm installed which requires me to use at least 93 octane. he also mentioned that it will burn up my "rings" because of the unused octane.

I was wondering how high of octane I can go before it gets dangerous for my engine. there is a gas station near me that sells turbo blue 110 octane. I want to use this every now and then. I just need to know what is safe to use as far as gas and what isn't

you can use 110 as long as it is UN-LEADED.
you really wont notice a difference with a stock riv on the street unless you have lots of KR. not worth the $8/gal that it costs.

btw, higher octane isnt dangerous, it burns more complete and reduces knock. lower octane is the dangerous stuff b/c it burns quicker.

You can only run as high an octane UNLEADED that you can find. I think 110 is leaded.

I've never heard of 'burning up rings' due to too much octane. You might have flameouts or various other ignition related issues but if you are just adding a few gallons of 104 to your tank which already has a few gallons of 93 in it you'll be fine.

I recommend dumping a gallon of toluene into a half-tank of gas and see what that brings you. Toluene is 117 octane and safe for your system as is.

o btw everyone 91 octane is disgusting. I had to put it in the other day instead of the usual 93 and wow can i notice a differrence. wot is terrible and i feel so lazy when driving now.....ugh can't wait till next refuel cuz im putting in some toluene!