I have noticed there are a lot of gas types out there lately. Looking to see what people have had the best luck with.

I know that with the SC engines you want to run preimium but there are differnet types of preimium around too! For example, Holiday has 93 octane but it is the "blue planet" gasoline which (i believe) has %5 ethenol in it. So would 93 octane with ethenol be better than say 92 octane without?

What gas have you guys used that has worked best? Have you found one station that has a better quality of gas for our cars than the other?

I read somewhere (might have been while I was researching water injection) that ethanol-based fuels were bad news on SC intakes. I don't remember why, but now I'm gonna go back and research it. With all the oil mergers around, there'* really only a couple major brands. Texaco and Shell are the same gas now, as are Exxon and Mobil. I don't know the rest, but I know Chevron shares with someone. I don't have any real preferences, but I do shy away from the 'generics'. BTW, water injection will allow you to run lower octane fuel. Yes, I had to get that in there......

FYI: Just make sure you get gasoline from a station that has lots of traffic. That way the gas will always be fresh. Stale gas can leave wax deposits in your system.
I use Petro Canada premium gasoline (Gulf). I believe the octane level is about 92. BTW: I drive a 92 SE with AC Delco Platinum plugs.

Ethanol based fuels or blends are supposed to have a slightly higher octane rating then normal gas. They should be better for high compression or high boost applications. At the same time however ethanol has fewer joules(of Energy) per gallon then gasoline does so you will get slightly lower mpg.


At 5% though i don't think it matters because there is just not enough ethanol in the gas.

For N/C engines you can run 87 octane. The engines were engineered for the low octane fuels. For SC engines it is highly recommended that you run at least 91 octane (by owner'* manual says that I can run regular or midgrade but recommends premium). I have tried 87, 89, 90, 91, 92, 93, and 94 octane and I prefer the 93 octane for price/performance. Beware, some states in the U.*. offer "economy" fuel at 85 and 86 octane, NEVER run this in our Bonnies as it will cause severe damage to our engines. Michigan does not alow gas stations to sell those fuels. They'd rather lead the country in per lane mile salt use to destroy our cars, forcing us to by new Detroit Steel every few years.

Methanol is detrimental to all plastic and rubber parts in our engines--avoid using Methanol blends, where as ethenol is not as bad. Willwren may know something specific about ethanol and SC'* that I haven't heard about.

Willwren, find out if this is in fact true. If so I'd like to know!

I'm working on it. I should know something by this evening, pacific time (to be specific!). I know some of the water injection guys are running an alcohol mix in the water, but that'* commonly done with Turbo'*, not SC'*.

STAY TUNED.

Ok, I did some homework.....read the following quote:

Efficiency of the Roots type tends to be lower though there are ways in which this can be improved. Teflon, PTFE or similar sealing strips can be inserted into the rotor tips to improve sealing. If the rotors are fitted to steel shafts, the unit can be run as high as 11000rpm. Charge heating will be much greater, but if the engine is run on methanol or methanol/nitro mix, the high latent heat of evaporation of these fuels will have a beneficial cooling effect.

(end quote)

So, as you can see, Methanol can be a benefit for intake cooling, although it is usually such a small amount that it probably won't make a noticeable difference. It doesn't appear to have any detrimental effects, either. High-mix methanol (85% to 15% gasoline) has been used in supercharged engines succesfully, and in some cases, with a 2-stage blower running 38psi of boost.

As far as Ethanol is concerned, I THINK the danger was in reference to people already running a water/alcohol mix in a water injection system. If that'* the case, running Ethanol-based fuel wouldn't be a problem with a NA, SC or Water-injected SC or Turbo UNLESS you were already running an alcohol mix (water injection on the Turbo should be AFTER the vanes to prevent erosion). BTW the latent cooling properties in a water injection system can reduce the intake temps by as much as 60° WITHOUT an alcohol mix.

Make sense to anyone, or can anyone shoot me down here?

Sounds good. The only concern that I have heard was that the alchohol can deteriorate rubber and plastic parts unless they are engineered to withstand both alcohol and petrolium based distilates.

BTW: How are you coming along on your H2O injection? I've been trying to follow it, but I am uncertain where you are at this point. Did I miss the thread that you updated a competed system? Or is it still in the works? I have essentially the same car (color/wheels, engine, just not SSEi trim) I think this would be a great mod if it works for you.

Your rubber and plastic concern is an issue, especially after you turn the car off. Any vapors still in the manifold can leak back up through the system. Pretty cheap parts up there for the most part.

H20 injection has been proven. My first prototype gained me 1.5 to 2 pounds extra boost. I really want to get this completed before I upgrade (or is it DOWNgrade) to a smaller SC pulley. That sucker runs hot enough already, but the H20 injection can cool it very well like I mentioned in my last post on this thread.

To prevent having to use an electrical pump, I'm building my own water tank, which will be pressurized to 35psi (regulated) from my suspension/utility air compressor. If you didn't have the compressor, you could use the spare tire as a pressure source. So I completed prototype 1, and I'm skipping #2 and moving right to what I hope is the final version. I picked 35psi for a reason.....don't laugh.....I got a fogger from a drip irrigation system that is designed to work at 35psi. This should work better than the true siphon-drip I used in prototype #1.

Yes, I've proven it, yes it works, and yes I'm pursuing it.....as long as my kids let me work on the car! This system should allow me to run lower octane fuel without knock, increase boost (by increasing air density), cool the intake by as much as 60°, and prevent carbon deposits in the guts of my car. I'm in the process of building my water/pressure tank. I'll start a new post as I make progress.

On a side note, water injection in an exhaust system can 'trick' your engine into thinking it'* either longer or shorter than reality, depending on where the water is injected. A much cheaper alternative to replacing the entire exhaust, but I'm not sure it'* really worth it.

And I didn't think anyone else was interested.......

Gordy you opened a can of rotten worms here !!


I, myself, always run the highest rated octane I can get (92-94) I have a series II na engine. I get almost 150kms better gas milage with high octane than i do with 87 octane.(regular)
There are people here who will argue until they are sick and dehydrated and die about this issue and will tell me i am an idiot (heh not the first time) for wasting my money. Some people will even say that i will ruin your engine and does it no good.
But i just go with the facts for me and what works for me.
ie: my previous Bonnie (1989) had a series I with 380kms on it. It always had premium (high test) run it from the day we bought it brand new to the day it was carted off to the wreckers. And we never had to do anything major to the motor.
My dad'* truck has 500K kms on it and it'* original motor in it and has had premium run in it by him from the day he drove it off the dealer'* lot.
In fact, I have run regular fuel in my car after a debate about this issue before. My car stuttered, hesitated, and otherwise ran like sh*t. Premium has always worked good for me...so premium it is.

That is your lecture for this week presented by professor Tamara.