Doug, The oil is not the problem. My dollars flowing the other way is the problem.

The racing fuels are typically not associated with the brand of fuel the station sells. Torco is an exception.

In the 60's, what octane did "premium fuel" have in the US? Here in Sweden, I remember as a kid in the early 70's, before unleaded came along, we could choose from three qualities, 93, 96 and 99 octane. Dad always filled up with the 99 octane, said the car drove faster. He might have been right I guess, even though it was just an Opel...

Octane ratings here were changed since our cars were new. It's now an averaged figure of RON and MON ratings. Formerly RON ratings were used. In 1970, Regular was 94, Premium was 100. Lead additive was phased out in 1971 and Regular octane dropped to 91 RON.

An engine will have a "favorite fuel" for whatever its state of tune. I had a '67 Honda 50cc cycle that would do 45mph on 87 octane unleaded, but would do 58mph on 106 racing fuel. Since it got 70+ mpg it was no big deal to spend the extra money for the racing fuel. It ran fine on either fuel, no knock, it just ran faster on high octane.

Goran , I think I remember using 100 octane too....Esso, Shell,BP....and Nynäs...Koppartrans...and OK...this in the 60`s......the days before Q8...

Adding to what Vikki has mentioned about the measurement system and definition changing for octane, here's where we discussed it several months back:
https://firstgenfirebird.org/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=23;t=003364

With my engine currently a perfect testing ground for knock issues, I will hook up a temp gauge and log temps vs. effects with various fuels. Cooling improvements may end up being the most efficient way to improve performance.

Jim, as you may or may not know there is no longer any American owned oil companies !

Marathon was the last one.

I personally won't buy gas at Mobil because there the largest oil company making those extreme profit's and you can't tell me they don't influence the market.

Fbody69...
Jim, Would you like to play a game?...I'll send you a quart of the TEH for experimental purposes if you wouldn't mind performing some for us.

Finally, the results are in!

First, I have to fill in the blanks on the test subject. It's a 69 Firebird that is so close to stock that it's easier to point out what's not like original 1969 equipment. The original 400 engine has a stock rebuild meaning original pistons, heads, intake, carb, exhaust..... So, it's running 10.75 to one compression. It has less than 1000 miles since rebuild so it's just broke in. The one part that's not like original is the distributor. It has the Accel electronic HEI and the Accel Supercoil. To accommodate these components, they are hardwired to the full output of the charging system(18-24 volts while running). The trans is the original TH400 with a fresh rebuild. The rear end has the original, special order, 3.55 safety track and that too has been freshly rebuilt. So, what you basically have is factory 1969 Firebird 400 non ram air exactly like you would buy it in 68/69 except for the ignition upgrade.


Test materials:
BP 93 octane unleaded pump gas.


Sunoco 110 octane racing fuel.


Max Lead 2000 Tetraethyl Lead Additive (Donated by Greg Fielder for the purpose of study)



The first test was done some time ago and that was straight 93 octane alone. The car ran ok on this fuel up to about 150 degrees when it started spark knocking to beat the band and I scurried over to Sunoco to add some octane.


Since I had 10 gallons of 93 already in the tank I decided to add 5 gallons of 110. This calculates out to about 99 octane. With this octane level, the car came to life! I'm going to use this level as a base line for the rest of the test for comparison. It's difficult to describe performance without experiencing it first hand. I will use three tests to try to convey the results.
First and foremost, sparkknock.
Second, what kind of a burnout it would do from a dead stop.
Third, how it hits the gears.

Results at baseline 99 octane:
No sparkknock at all.
It burns the tires for just under a second and then scoots.
The tires break loose momentarily when it hits second and third gears.

Results with 12 gallons of 93 octane unleaded fuel and one quart of lead additive
No sparkknock at all.
A slight burn out from a dead stop. Definitely a drop in performance.
The tires still have a slight chirp when hitting the gears. I noticed a slight bogg at times when trying a heavy acceleration.
There was a noticeable drop in operating temperature. The temp never reached 180 which is passed when using baseline 99 octane. Temps reach 220 at times with 99 octane.

Results with 12 gallons of 93 octane with 5 gallons on 110 octane and one quart of lead additive.
Same performance levels as baseline 99 octane with one difference, lower operating temperature. Again, the temps never crept over 180.

Jim, Thanks for sharing your study.

Many years ago I saved an article from Consumer Reports where they were addressing the demise of unleaded premium while leaded regular still existed. Suprisingly, lab studies of 50% 89.1 leaded regular mixed with 50% 91.6 unleaded premium offered an octane number of 91.2 which is much closer to the premium number than a proportional calculation. As they put it, "...the first bit of added lead has a much greater impact of raising octane level of gasoline than the rest...."

I think that one of the surprises, to me, was that the spark knock went away with simply adding lead. Another unexpected thing was that the more lead you added the cooler the engine ran. The lead seams to smooth out the combustion and also lubricate.

This place: http://www.maxlead2000.com/

Will sell you the above product for $30.00 per gallon (in quart bottles). So I bought 2 gallons and they shipped it to VA, USA for $69.00 including shipping. $8.60 per quart is fairly reasonable if it means saving our cars!

You need this stuff! If you have unhardened valves and seats it's a must to run a couple quarts through to get a protective build up. Also, it doesn't hurt to have it for cooling purposes. It's not quite as good as higher octane for performance, but, at least you can run your car if there is nothing over 91 available.

Jim, please clarify on the following:

1. The original 400 engine has a stock rebuild meaning original pistons, heads, intake, carb, exhaust.....
Are these Pontiac pistons on standard bore, or aftermarket pistons on .030" over, etc.? Cast or forged? What cam? How is it degreed? What brand, composition, and compressed thickness of head gasket?

2. So, it's running 10.75 to one compression.
Is that calculated with all the engine build details, or simply relying on the advertised figure Pontiac used, which has no basis in reality? Do you have your cylinder cranking pressure reading?

This is simply to get a better idea of the details of your baseline. Mine is the original unrebuilt '69 400 with 76K miles, steel shim head gaskets, the whole shot. The only changes are the timing set and a Pertronix Ignitor II in place of the points.

If you take 12 gallons 93 octane and 5 gallons 110 octane, that gives you 98, but close enough anyhow. Our cars were rated for 100 octane so the minor changes you've made should make that bleand palatable.

I've been running Max Lead for 2 years, one quart per tankful. It helps, but my car has more power and runs cooler and permits more advance on a 50/50 blend of Turbo Blue 110 Leaded + Super Unleaded 93 without a doubt. If the leaded fuel was regularly available close by I would not use the Max Lead at all, but it's good to be able to carry a bottle in the trunk in case I am away from good fuel.

I'm glad you took the time to check. Glad to find it is beneficial to our cause. Glad to know someone else is getting some a buttload cheaper than I've been paying for it. Dang glad I came across you folks.
I'd been running the lead for quite some time, but not at that high of concentration level.
Now all I need to do is figure out what else I can add to enhance the performance side, other than the race fuel. It would be fine as I leave town, but replacing what I burn up will be less than practical when I get 200 miles down the road.
Thanks again to Jim for taking the time.

When using a dynamic compression ratio calculator, which cam spec is required, @.050" or seat?

You can bet it was my pleasure, Greg! I really appreciate the opportunity.

Vikki,
The engine had 20,000 original miles on it when it was rebuilt. It was rebuilt using all NOS parts. It has the original bore and cam specs. I'll happily provide any further specs but I time it by ear. I can't see going to the trouble of a light when you can time it by ear. If I ever loose my hearing I'll definitely get a light. I haven't run a compression test. I would only use the results for comparison between cylinders. I have yet to see a test give acurate results. I can asure you that the compression ratio would be exactly the same as a new factory engine.

That's great that you found NOS parts. It may not seem significant, but even a minor keyway change can make a big difference. I was wondering if you degreed the cam with a factory timing set for comparative purposes. I didn't mean ignition timing, sorry if I was unclear on that.

There is a point at which knock occurs, temperature, pressure and fuel are the factors involved. Cam timing and compression ratio control the pressure, user controls the fuel, and there are various ways to control the temperature. I haven't yet found cranking cylinder pressures from a 1969 400 road test, if anyone has them please share.

Can you use 100LL (low lead) aviation fuel? Any experience? Lots of self serve pumps these days at small airports.

I just called our local airport and she said it HAD to go into an aircraft. I called a little airport and SHE said that you had to have an "N" number, but sometimes her boss would approve the purchase in smaller amounts. It is 100LL. While that doesn't answer your question, it does offer some insight to those of us that got to thinking about it.

I have heard that it works great.

Here in little old Schenectady, NY we can get 110 and 112 octane "racing gas" at one of the Citgo stations. I've got to believe it's available in most places if you just know where to look, unless it's not legal in certain places.

I run 83 octane pretty well...its a 72 model 400 rebuilt so I assume hardened seats, driven 16000 miles plus since I got it...no pinging, never added lead.... got 5C heads , milled to 88CC, assuming +_ 9.2 CR...

I used to go to our airport with 2 five-gallon cans and fill them with the green avation gas. My 69 Judge ran great with that stuff in it. When the gas went from 93 leaded around here to 93 unleaded, that's when the pinging started in normal driving. That was around 1980 or 1981.

You can't do a burnout with a stock Firebird 400 Man, I can lay down posi all the way through second gear if I want. I would check your timing and take a look at that carb.

Quote:"You can't do a burnout with a stock Firebird 400 Man, I can lay down posi all the way through second gear if I want. I would check your timing and take a look at that carb."

You probably got yours jacked up so that the tires can't hook up. Maybe it was when you cut your front coils? You lost your weight transfer. Spinning all the way through second isn't what you want. If you ever make it to the track you will understand that. At face value, your post is a jab. Maybe you should check yourself and think about being positive if you are going to post. Maybe you could find it in yourself to be positive?

Jim, I forgot to ask before; why did you use a full quart of the Maxlead 2000? From the chart on their bottle, 12 gallons might need only about a cup of the stuff to get to the 99+ octane. Right now I have about 12 oz of it in my car.

The way I read the chart on the back of the bottle, the one I posted, it shows that it takes 48 oz. with 20 gallons of 93 octane fuel to reach 103 octane. That's 2.4 oz. a gallon. With 12 gallons that would be 28.8 ozs. To take into account the residual gas in the tank, I thought the full 32 would be good. I did this to push the lead as hard as I thought relevent to see if it really could produce the performance levels I was getting with the 99 octane fuel. Without taking it to this level, I don't think I would be confident in saying that the lead just doesn't reproduce the effects of higher octane fuel. Also, I was a little leary of using my engine as a guinea pig and wanted to be sure there wasn't any hidden detonations and at the same time, get a good buildup of lead in my combustion chambers.

OK, understood. I was just reading the unleaded/leaded mix 99 octane as the comparison level. When I added the 12 oz to mine to get to 99+, the pinging I occasionally heard disappeared. I still have some oil-based lead substitute also in my tank to protect the valve seats.

Product update:
Actually, this is what my dear old Pop "remembered" from his circle track days (in the mid-late '60's)
-
Take premium fuel (for that day in time)
and add 10% toluene and to that, 4oz of propylene oxide to 5 gallons of fuel.
-
Watch it, I say boy watch it fizz (foghorn Leghorn)
Have we any chemists out there reading this long winded post?

Yah Jim. The pinging went away at the lower levels but I just couldn't get the power I had with raw octane no matter how much lead I added. Kind of like when your car is running hot and you are getting robbed of power.

Greg,
I went to college for chemical engineering but I think you would need to be a special kind of chemist to know about that mixture! I did understand the article on specific gravity of todays fuel in High Performance Pontiac this month. It basically says that todays fuels are 'all over the map' as far as density and how good a particular brand is. They recommend to stick with the major brands because they have more accountability with their product than the discount brands. The good ones are like Sunoco, BP, Amoco ect. because they have the fuel from the crude stage all the way to the finished product. One thing that is a let down is that the higher the percentage of Ethenol the lower the specific gravity. That makes it less dense and have 'less bang for the buck'.

Thanks Greg and Jim,

What a great thread. I was so impressed with your test that I drove to Columbus, IN and picked up 2 gallons of the Max Lead. (Very Nice people)

I will be mixing the 93 octane fuel with 110 that we can by here and adding the Max Lead.
I hope that my ear fall off when my 68 firebird 400 wakes up.

Thanks again

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">I just called our local airport and she said it HAD to go into an aircraft. </font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">It's a Fire bird , wouldn't that qualify?

Hey there,
Don't blame us, it was Doug R that started this mess. But it has been fun and informative. I personally, due to Jim's cooperation was able to confirm one belief in that the lead is truely a good thing. And was also able to confirm one great suspicion in that the lead isn't EVERYthing.
It's been a blast.

It's good to know that you came up with the same results I posted here a couple of years ago, testing with a similar engine configuration and with the same brand of lead supplement. The biggest difference is that my 'bird responds best with a 50-50 mix of 110 and 93, rather than a 12-5 mix.

Fuel brand selection is still important; my 'bird does not like the fuel available from the local Mobil station but runs fine on BP. It's easiest to feel fuel differences in low speed driving with no added octane and no lead additive, with only a couple of gallons added to an empty tank.

QUOTE"It's good to know that you came up with the same results I posted here a couple of years ago, testing with a similar engine configuration and with the same brand of lead supplement."

Yah, and it's the same as I posted here 4 years ago. LOL The only thing that's changed is the prices, availability and test vehicle!

Since we're running lead anyhow, it seems like it would be more environmentally responsible just to have it at the pump for us.

QUOTE"The biggest difference is that my 'bird responds best with a 50-50 mix of 110 and 93, rather than a 12-5 mix"

That must be an ignition thing or the difference between a brand new rebuild and an original high mileage engine.

That's why I wondered what your cylinder cranking pressures are.

After I get all the grunge work out of the way I might have time to do a cranking test later. Do you want it hot or cold, wet or dry?