My local choices for fuel here in the State of Utah, USA are either 91 "premium" with 10% ethanol or 88 "regular" without any ethanol. My engine is a recently rebuilt 3.8 litre with 9:1 pistons. I am inclined to use the 88 non-ethanol gas and possibly add an Octane booster to the mix or perhaps some non-leaded racing fuel with about 95-100 octane rating. I am skeptical that octane boosters actually do any thing. at all. and the racing fuel mix is problematic ( not to mention possibly illegal). Any suggestions as to which way to go ? AND... if anyone knows of a real octane booster that is any good ? As always, thanks for your thoughts !
Schmitty

 

it's pretty simple to create a real honest-to-god octane booster so i have faith that they do pretty much what they are supposed to. however, it wouldn't surprise me if they have a bad reputation for falling short of expectations, inasmuch as many people are, unfortunately, under the impression that octane or premium gasoline is in some respect "better" than regular gasoline and will provide, in and of itself, added horsepower. and that's simply not the case. a little research on the net will dispel that misconception.

however, it does need to be pointed out that since the proliferation of electronic fuel injection (EFI) systmes, with full monitoring and the capability to dynamically adjust spark and injection timing, etc., it's possible that the ECU in a high compression engine will have various factors adjusted depending on knock-detection and consequently lower HP by a small margin. this was not the case on carbureted cars twenty or thirty years ago. one simply had to run the proper octane gasoline to prevent pre-detonation. now, for all intents and purposes, one can run any octane rating in any new car and the ECU will do what is necessary to prevent knocking.

does this mean that just about every modern car can run safely and efficiently on regular gas, as the ECU in conjunction with the EFI system will adjust to the octane in the gasoline you purchase? yes.

 

Between a rock & a hard place other than retarding timing to prevent knock.
There is nothing wrong with ethynol as an octane booster as long as your fuel system components can tolerate it. e.g. elastomers/rubber components etc. Jaguar's original Nylon fuel piping tolerates it well ~ the new stuff not so well (see below). You might have to richen mixture a little. Keep your fuel dry. Any phase separation due to water being present, can lead to corrosion. Especially with yellow metals present or in the alloy. The alcohol dumps into the water phase.

MTBE (methyl tertiary-butyl ether), TBF (tertiary butyl formate) and TBA (tertiary butyl alcohol) are genuine octane boosters. Look for products with high concentrations of these. I'm not getting into brands here.

In lead free fuel there is no doubt that refining up to the required octane level is beneficial but it costs.

Never fill up at a gas station while a tanker is discharging & stirring up the tank bottoms.(which usually contain water & other crud. Our old cars do not have knock sensors & high speed knock can be difficult to detect even to the trained ear.

Now withdrawn by Barratts & Moss. About 2 weeks exposure to Sasol fuel alcohol 10 to 12% max.

 

If you are using the "original" SU pumps, I would be careful of leaving the ethanol fuel standing too long. Im not sure about whether those clear vinyl(?) fuel lines are ok with ethanol. The tanks do have drains so at least its not totally insane to think of draining fuel occasionally. I agree that the idea of "octane boosters" being a bit towards the snake oil realm, but it you read the label for Glyns ingredients it should be safe. I have used various brands without perceptible difference. Maybe I dont drive hard enough.....

 

I have modified my post above to cover Jerry's worries about Nylon fuel piping.

 

I'll echo Glyn's comment on 'nylon' pipe. The genuine material is excellent, better than any 'rubber'. If you need to replace some nylon tube, I'd suggest buying it from a specialist supplier of nylon pipe, otherwise you'll likely get something useless.

The octane requirements of engines isn't a simple relationship with octane number. Different engines may have quite inconsistent sensitivities. Large oil companies spend a lot of time and money testing cars and engines. It's not impossible to find an engine that knocks on 91, but not on 88 with ethanol. Also the margins allowed by the engine manufacturer will change with operating condition. This may become more noticeable after the cylinder head or block are skimmed and, taking the previous V12 HE engine in my Daimler as an example, the engine knocks under steady cruising, but the knock ceases when the throttle is opened. Nowadays, with knock sensors that allow the ignition to be retarded when necessary, things are safe and simple for the owner. But that doesn't apply to our old cars or anything from more than 30 years ago.

Incidentally, I used to tip various types of anti-knock in my Daimler. It wasn't clear that any made much difference; possibly the Castrol product had some effect. We eventually resolved the problem by swapping to a later engine from an XJS.

Personally, I buy premium fuels from major oil companies because I expect (or know from earlier in my career) that the cleanliness additives actually work, which is relevant if you are someone who keeps their car for several years (I've never sold a Jaguar).

 

I'll back Peter's comments on apparently identical engines displaying different knock sensitivity having done many octane tests on the road. One incandescent deposit can make a difference etc.

 

In Australia we have a federal government which has laid down the law on fuel standards. (Thank goodness)
We have
91 octane unleaded.
94 octane with 10% ethanol
95 octane unleaded
98 octane unleaded
Some states have attempted to introduce laws requiring all fuel to contain ethanol, but the federal government law does not allow that to happen.
A friend who is in the specialised oil industry has shown me some pretty alarming photos of the problems developed in engines and equipment using ethanol fuel.
Consequentially I will not use any fuel containing ethanol in any of my machinery including cars, aeroplanes and rider mowers.
I suggest Schmitty steer clear of ethanol fuel.

 

Being able to buy 98 RON in Aus. was always magic. Schmitty is talking about AKI i.e. the average of RON + MON as displayed on US pumps.

Some of Brazil runs on 100% hydrous & anhydrous alcohol dependent on the sugar price they can get. Certain fuel system components are cast out of pure zinc as a result. No yellow metals in sight to catalyse corrosion.

They play the sugar vs. alcohol swings & roundabouts dependent on value.

 

I spent some time in Brazil (locals spell it Brasil) in the early 1990s at Sao Jose dos Campos learning to fly the Embraer 120 Brasilia which is a 30-passenger turboprop.
My group of 6 hired a VW Kombi which ran on "alcol" alcohol consisting of a mixture or ethanol and methanol alcohol. It had some chemical added to stop the derelicts drinking it. (oil of mustard?)
The main tank was about 60 litres of alcol and the "gasoline starting tank" was about 4 litres.
If the engine was cold, there was an automatic injection of gasoline to start the engine when you hit the starter switch.
The price of alcol was half the price of gasoline.
The Kombi did not lack power and I have a photo of it at the 7000 feet mark in the eastern alps happily chugging along. That height is also the same the highest mountain in Australia
The point I am trying to make is that Brasil has mastered the concept of alcohol as an alternative however vehicles need serious re-design criteria to achieve this.
Trying to force older vehicles to run on ethanol-based fuels is stupid.

 

Yep. VW led the way in building vehicles suitable to run on alcohol. VW even build buses & marine engines in Brasil, as they correctly spell it. They are a large customer of ours much to the disgust of Petrobras & Ipiranga.

 

The type 158 and 159 Alfettas ran nicely on methanol in the first years of F1. Shell had a Porsche 944(?) running on E50 in the 1970s. In many ways (apart from the problems mentioned), alcohols are quite attractive fuel.

 

And we know how to lubricate for them Peter.

 

I thought of you today when I was filling up and the tanker truck ( B Train) was at the station. I asked the attendant how long it takes them to go though that amount of fuel ( 62,000L) and he replied 3-4 hours, saying they typically get 4 trucks a day. Given that amount of fuel going through the underground tanks, would it ever really settle - or conversely, would it ever be contaminated? I'm assuming that the station pumping system also has filters, is there any cause for concern? I've never had a problem in my car ( 2007 X-Type) and I can't remember the last time I changed the fuel filter.

 

More fool you for not changing a fuel filter. I have an XF Sportbrake with a full service history from the previous owner. Driving down a dual carriageway over taking some large lorries and the engine cut out. No power steering and an auto box so no dipping the clutch and free wheeling. Managed to get over to the inside safely and stopped but had a big red triangle on the dash. Got the RAC out and it turned out to be a blocked fuel filter. Did not appear that the fuel filter had been changed during the recent service. ECU was not getting enough fuel so just switched the engine off. Very scary and lucky I was driving and not my wife.

 

At that consumption rate you are pretty safe. The crud is being shared over many vehicles. The station is ridiculously undertanked. I'm talking about drops every few days. We have permanent crews cleaning tanks & you would be surprised what comes out of them. In Gasohol areas pipe corrosion in the network can be an issue as well. I had Donaldson 1 nominal 3 absolute hydraulic filters fitted to all our pumps in that area. But that was far from the norm. No other oilco did it. You would have cars getting stuck a few blocks from the filling station. Finally kicked Sasol into action to fit huge bag filters to their pipelines.

 

This is at a Costco and I have no idea why the tanks are that small. They can have 18 vehicles fueling at a time and there is always a lineup for the pumps. When I was there today they had 2 B-trains there. I'm pretty sure most of the fuel comes from either the Shell or Suncor refineries in Edmonton.

I used to change fuel filters in my cars and I always cut them open to see what was inside - I never found debris or water; it was clean media so I quit changing them.

 

My father always said to avoid filling from stations if they were re-stocking or had recently and I've always followed that advice. However, the tanks in the filling station aren't the only source of crud in the fuel. There's general dirt and dust in the atmosphere. No, it shouldn't get into the car's fuel tank, but it does. If you've lived in southern Italy and experienced the blood rain, heavy rain full of sand from Africa, you'll know it gets into everything. There's also rust from corrosion of the car fuel tank. And, of course, even fuels without ethanol degrade, producing acids, gums, and deposit. Gasoline from a major will have stabilisers and should be good for six months or more - I don't know if that applies to Costco or Tesco!

 

Sounds like raining mud in Beijing when prevailing winds blow dust from the Gobi Desert.

 

Costco claims that they are TopTier fuel, which meets the same spec as Chevron and Shell. https://www.toptiergas.com/