Sanity, thanks I was about to get all wee weed up.

 

Too much fun!

 

Thanks, I'm sure you are right. Do you think the leaky injector is affecting any thing else? Like MPG or performance?

 

Yes. I really think so.

 

Thanks, John. Good to hear from you again. Jay from Minnesota

 

For my freshman engineering project at UCLA I did an analysis of various brands and octanes of gasolines (this was in 1964, so of course things might have changed...). One thing I found is that HEAT CONTENT is what makes power. The lower octane fuels have higher heat content because they aren't "diluted" by the "light ends" that make higher octane. This is offset by the higher spark advance that you can put into engines running higher octane fuels. The net effect is that you get higher power with higher octane fuels.

This was great back in the day, but our L98 ECMs are calibrated to the low octane fuel so you can't get the advantage of the higher octane unless you tweak the tune to put in more spark advance.

Another side effect of this is that the original "ideal" AFR of 14.7:1 programmed into the EPROM is no longer true if you run oxygenated fuel. The oxygenated fuel is more like 14.5:1. The ECM will compensate, but the "ideal" BLM values of 128 will shift. I'm beginning to question that number anyway. Where does it come from? Internet myth? If you do an ECM reset it will set all the BLMs to the default value of 120, so why 128? The range is 108 to 160, so 128 isn't even in the middle.

 

Interesting thoughts on the BLM. I am sure most will chime in that do tuning.

 

Last year I spent about 6 months going through the BUA firmware in my ECM. The original disassembly was done around 1995 or so and the persons involved (Ward Spoonemore and Bruce Plecan) are both gone (so we can't ask). I found MANY errors and problems with the comments. I did a web page on this:

http://home.earthlink.net/~cliff_har...5/BUA/BUA.html

A lot of these "myths" get posted by somebody with good intentions but then they get misinterpreted and reposted and reposted and become absolute truth by repetition. Here is an excellent example, the L98 engine start sequence, which has been posted EVERYWHERE:

http://www.corvettebuyers.com/c4vettes/l98.htm

Under the "ECM reaction" section, it says, "In the L98, all injectors on one side of the engine fire at the same time followed by all injectors on the other side firing at the same time." I call this the "bank fire" myth and it is NOT true. I think it started because there are two injector fuses, one for each bank. The light blue and light green wires from the injectors go to the ECM AND ARE CONNECTED TOGETHER INSIDE IT. There is only one injector driver and all 8 injectors fire at the same time.

Another thing I think is interesting: there is much emphasis on the spray pattern of the injectors. The injectors fire once for each revolution of the engine. Cylinder #1 (for example) only fires on every other revolution. That means that the injectors are firing twice for each time cylinder #1 fires and spraying against the back of a CLOSED intake valve. The fuel just sits in a puddle in the intake passage until the intake valve opens. I have heard two scenarios related to this: (1) the fuel is instantly vaporized when the intake valve opens and the air/fuel mixture blasts into the cylinder. (2) the head of the intake valve is hot enough to keep the fuel vaporized while it sits in the intake passage. I have never seen any proof of either or both of these "theories".

 

Great info Cliff, thanks for sharing!

 

In most of the U.S., regular gas has an octane rating of 87, midgrade gas is 89, and premium is 91 or 92. (Octane ratings are lower in the mountain west due to the effects of thin air on internal combustion.) Contrary to widespread belief, the octane rating doesn't indicate how much power the fuel delivers; all grades of gasoline contain roughly the same amount of heat energy. Rather, a higher octane rating means the fuel is less likely to cause your engine to knock or ping. Knock, also known as detonation, occurs when part of the fuel-air mixture in one or more of your car's cylinders ignites spontaneously due to compression, independent of the combustion initiated by the spark plug. (The ideal gas law tells us that a gas heats up when compressed.) Instead of a controlled burn, you get what amounts to an explosion--not a good thing for your engine. To avoid this, high-octane gas is formulated to burn slower than regular, making it less likely to ignite without benefit of spark.

Use whatever your manual suggests.....

 

I think I'm going to purchase a Corrolla. After all never break and will run on anything that burns. HlhnEast has sold me. Just Kidding!

 

hey, Dont hate on the Corollas. Some of them are "S" models with no tilt or cruise control.

 

I can see why engine timing is boring.....

 

For a DD, depending on the situation, a Corolla is an excellent choice. You can't tear them up.

 

[QUOTE=93Rubie;1580930006] Only if you have a non-90 L98. They are only 84 L83 is 9:1 and the rest of the L98's are 9:1 or 9.5:1. in 90 they went to 10:1.

I don't consider 10:1 to be low compression I would run premium.
The LT1's are even higher at 10.5:1 and the LT4's are 10.8:1.
I would NEVER NOT run premium in these engines.

 

Same car here - 85 basic. Um, what weight oil is best?

 

SERIOUSLY?!?

Your trying to hijack a gas thread with an oil question?
Does it get any better?

 

Are YOU serious? Why not just answer the question and move on? Or don't answer it and move on. Not everyone has alternative motives. I thought the thread was for an "85 corvette". I will try to be more carefully in the future my high and mighty exhalted master of the Internet. Looks like somebody got up on the wrong side of the bed and stepped in his pee bowl.

Now, would somebody care to let me know what the proper oil weight is for a basic 85?

Thanks

 

You just got told Coach
Hey nOOb, you did Hi-jack this thread, then slam a member who has been here 8 times longer than you, and then you expect everyone to jump in here and help you. Good luck.

 

And with that, the rest of us are going to sit back and enjoy the carnage