Change in octane?

[Scuppers]

I was a holiday party this week and met a self proclaimed expert in marine engines. When he found out we have a A4, he proceeded to tell me why we should switch to a new high pressure diesel. The usual stuff except for his beliefs about octane changes over the last couple of decades prevent carbureted fuel systems operating efficiently. I have done some looking online about gasoline changing so that fuel injector can help in mileage and emissions. In changing the fuel, it no longer works like a old engine like the A4 was designed for. I have not found any reference specially about that. Obviously the do work with A4's but... Is this true, should there be a concern.

mark

[romantic comedy]

he wants you to use high pressure diesel fuel?
it is a gas engine, that needs gasoline.

[Scuppers]

The reference to the high pressure diesel is that they are suppose to burn cleaner than the older diesels.

My question; has gasoline been re formulated for fuel injectors and if so, is that a concern for theA4?

[ndutton]

Did he say what had changed about the octane? Seems to me unless math has changed somehow (who remembers voodoo economics?) the octane rating is the octane rating, period. I dunno, the comments strike me as overly vague. Is he saying 87 octane isn't 87 octane? Is it something else? I'm just arrogant enough to have peppered the guy with questions waiting for him to step on his tongue. If he didn't I'd have learned something new.

I'll check with the chief engineer at Edelbrock on Superbowl Sunday to see what he knows.

This guy is either pretty sharp or a colossal blowhard. I'd like to know which.

[Mo]

Gentlemen,
I've been using NGK XR4 plugs for 3 full seasons now...they run hotter than anything we have been proclaiming and I was told to use them by an experienced engine rebuilder (1000's per year)...anyway, my mileage improved, I have no crud on my plugs, and haven't had a problem with the engine as such.

I have a real liking for Bosch plugs and would like to find an equivalent. NGK and Bosch were always winners...I have a spare set of NGK on the boat and have never had to go to them...

Relating to the noted article, I wonder if a hotter running plug is a simple answer...has done wonders for mine.

[YOUTUBE]http://www.youtube.com/watch?v=0zg-X...-21cZOyAvH1D0g[/YOUTUBE]...sorry guys, no engine in use here...it's my backup

[67c&ccorv]

Me thinks he wants you to exchange your A4 for a diesel...and I bet he gave you his business card.

[HalcyonS]

re NGK XR4 plugs

I'm keen to hear anyone's response to this - thread hijack as it is

[ndutton]

Me thinks he wants you to exchange your A4 for a diesel...and I bet he gave you his business card.

His name wasn't Joe DeMers was it?

[jbsoukup]

my understanding of octane is that it is an additive to prevent detonation.
A low compression engine such as our A-4's don't need a high octane fuel.

Mine has run with water in the fuel and loose spark plugs (not on purpose)
put a little water in a high compression diesel and see what happens.

diesels have been around a long time, so why would the Navy put a gas engine(the utility 4) in their lifeboats in WW2?

Reliability?......

[jbsoukup]

By the way, is this guy a sailor? or just a mechanic.

[The Garbone]

I was under the impression harder valves to deal with unleaded gas and ethanol resistant fuel lines to deal with rot were the big changes over the years.

I think you do loose about 10% efficiancy due to ethanol but can run marine gas without it as long as you don't mind the exta buck or so of cost.

On my old thumper motor bikes I run NKG plugs and a Bosch blue coil. I do foul them out every few 1000 miles but that is because I live in Florida and run the bike rich to keep the temp down on the air cooled head and iron barrel. I would think you can run a bit more lean and efficiently due to water cooling and less concern about heat disipation.

[jbsoukup]

I don't know about harder valves, but I believe the MTBE they add is supposed to be a lead substitute? Wasn't lead added for valve lubrication?

I know a lot of fiberglass fuel tanks were damaged by ethanol fuel.
Mine is aluminum, I didn't change any rubber, and it's fine after running 87 octane pump gas for 10yrs.

[The Garbone]

I don't know about harder valves, but I believe the MTBE they add is supposed to be a lead substitute? Wasn't lead added for valve lubrication?

I know a lot of fiberglass fuel tanks were damaged by ethanol fuel.
Mine is aluminum, I didn't change any rubber, and it's fine after running 87 octane pump gas for 10yrs.

The rubber eating thing may be specific to my brand of 3rd world motorcycle. Came from India with real rubber hoses and a rubber carb manifold that lasted about 3 months before starting to leak.

The vavle thing is before my time but that is what I read on the interwebs so it must be true....

[jbsoukup]

gonna post here because I made some changes to my profile and I want to see how it looks. as far as the inter web, all hail the mighty google!

[Scuppers]

I'm checking on his name, we were in the Long Beach area.

Not sure if he is a full time mechanic but is on many "runs" to Mexico as the mechanic. He seems to be really into only motor boats, big motor boats. And electronics, he hand nothing good to say about xantrex inverter/chargers either.

His story was when fuel injectors became more common in cars with hope of reducing emissions and increasing fuel economy the clogged easily and didn't hold up very well. So the fuel companies changed the formula.

The fuel is suppose to have a lower boiling point creating more fumes and carburetors have a had time dispersing the fuel in the proper ratio to burn completely. Hmmmmm I haven't found anything about changing the burn temperature.

I remember as a kid driving a series of triumphs that "regular" octane was something like 87 and I could get 95 mph and with premium, 93 octane, I could get over 100.

I have been told the A4 has harden values and seats and because they were designed for marine industry the gaskets would be eaten up but the ethanol.

My hope is do rebuild this year and keep the engine as original as possible. The usual gauges SW oil pressure, water temperature, tac and fuel/air mixture gauge.