Octane Rating question...

i30dvr · 05-05-2008, 09:57 PM

i know there have been many threads on whether running 87 or 93 makes a big difference. I am wondering if it would hurt running my dek on 93 mixed about 70/30 w/ 100 lo-lead fuel. What would the effects be? preignition?....any help would be awesome..

*mowgli29* · 05-06-2008, 09:32 AM

Quote:

Originally Posted by i30dvr

i know there have been many threads on whether running 87 or 93 makes a big difference. I am wondering if it would hurt running my dek on 93 mixed about 70/30 w/ 100 lo-lead fuel. What would the effects be? preignition?....any help would be awesome..

First of all, where are you getting leaded fuel?

Secondly, IIRC, won't leaded fuel damage o2 sensors or at least make them inaccurate? Granted it's not straight leaded fuel, but I would think they'll crap out alot sooner than they should. I know my wideband says either leaded fuel will damage the sensor, or I'll have to calibrate OFTEN. I think it just says it will damage the sensor.

Thirdly, what would be the advantage? Cheaper than buying race gas? Is this for DD or track use?

**nismology** · 05-06-2008, 09:54 AM

WRONG SECTION.

Moved.

*SilverMax_04* · 05-06-2008, 11:53 PM

The first point: It is ILLEGAL in the USA to burn any gasoline containing any lead additive on any ppublic street or highway in the country. Some race vehicles are not covered by this law, but they do not run on a public street or highway.

Second point: The lead in even low-lead gasoline will damage the cat converters and the oxygen sensors in your vehicle.

Final point: You can find most of your questions about octane answered by one or more of my posts on this older thread on this site:
Octane Number and what it means

Check my first post for the different topics and their post number on that thread.

*mowgli29* · 05-07-2008, 07:19 AM

Quote:

Originally Posted by SilverMax_04

The first point: It is ILLEGAL in the USA to burn any gasoline containing any lead additive on any ppublic street or highway in the country. Some race vehicles are not covered by this law, but they do not run on a public street or highway.

Second point: The lead in even low-lead gasoline will damage the cat converters and the oxygen sensors in your vehicle.

Final point: You can find most of your questions about octane answered by one or more of my posts on this older thread on this site:
Octane Number and what it means

Check my first post for the different topics and their post number on that thread.

Seriously? I didn't think it was ILLEGAL! I know someone who has an old 66 mustang v6. He doesn't drive it much, but when he does, I'm pretty sure he has to use a lead additive. Maybe he doesn't HAVE to, but he does. Maybe since I live in the middle of the woods where emissions don't apply, this rule doesn't apply either?

i30dvr · 05-07-2008, 09:24 AM

well the lo-lead is from the airport....i have connections and get get aviation fuel.....i mainly use it for my 70 oldsmobile w/ 455 BB bored .30 over...etc...

*SilverMax_04* · 05-07-2008, 12:38 PM

I don't know the details of the law, but know that if your vehicle has a catalytic converter in the exhaust system, it is definitely illegal to burn leaded gasoline in that vehicle on any public road or highway. This is the law, even in the back woods anywhere in the USA.

I don't remember when cat converters became standard in exhaust systems, but suspect that it was after 1970 -- so I suspect that both of those vehicles are not a problem burning leaded gasoline.

I also think (but don't know for certain) that it is illegal to burn leaded gasoline anywhere in California.

scheibler · 05-07-2008, 12:38 PM

what do you mean u live int he woods? I'm from stl too...where u at?

*mowgli29* · 05-07-2008, 12:40 PM

I'm actually about 50 minutes west of STL. Nobody has heard of where I live, so I say STL because most poeple know where STL is!

I don't want to get the thread OT...PM me.

*mowgli29* · 05-07-2008, 12:41 PM

Quote:

Originally Posted by SilverMax_04

I don't know the details of the law, but know that if your vehicle has a catalytic converter in the exhaust system, it is definitely illegal to burn leaded gasoline in that vehicle on any public road or highway.

I don't remember when cat converters became standard in exhaust systems, but suspect that it was after 1970 -- so I suspect that both of those vehicles are not a problem.

I also think (but don't know for certain) that it is illegal to burn leaded gasoline anywhere in California.

I could see that. And yeah, I didn't think about it, but the year totally makes a difference. Also, there are cars that are registered as "historic" cars which don't have to pass emissions. Well, at least around here anyway...

Can anyone answer the original question? I'm kidna curious what the result of mixing fuel like that might be.

*SilverMax_04* · 05-07-2008, 12:51 PM

Quote:

Originally Posted by mowgli29

...Can anyone answer the original question? I'm kidna curious what the result of mixing fuel like that might be.

Octane blending is not exactly easy to accurately predict. But for a close approximation, you can average the octane numbers to get an approximate average. But you need to be certain you are using the same octane values before getting an approximate average. There are three different measures of octane -- 1)Research Octane, 2)Motor Octane and 3) the average of (R+M)/2 -- the value posted on all commercial gasoline pumps in the USA and Canada.

The 100 octane Av Gas that is used in piston powered airplanes is a Research Octane measurement and can't be averaged with the 93 Octane Number posted at your local gas station. If this is what you want to do, I can give you a rough guide for getting an approximation of the blending result.

You can also go to my earlier posts to learn more about octane and what it means:
Octane Number and what it means