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Lead additive/octane boost/curtail KR??

97grandprix1

97grandprix1

New member
I've used lead additive in my racing truck intermittently for years and always noticed a difference in performance, and I know it increases octane. Some other octane boosters have increased performance too. I am curious as to whether anyone has experimented with the lead additive to increase engine life or even calm KR. My race truck is 10.5-1 SBC cam/heads/intake/hot ignition/carb. After 8 years of keeping the hammer down it still doesn't smoke (at all), and the compression is within 10 lbs per cylinder. Really I'm trying to determine if anything I've done to help this engine last can do good to the series 2. Now that I think about it maybe the CAT wouldn't like lead, still...Anyone...
 


Well you can increase octane to control KR without nasty lead additives by adding other high octane petroleum distillates such as Toluene (114 octane) or Xylene (116.5) to your fuel.

Don't know about the 1997 specifically, but since it is ODBII it should be able to advance (or is it retard?) your timing to accommodate the different octanes. Routinely added a gallon of Toluene (free from work) to 9 gal of 93 octane gas in my 2001 3800 Firebird and it lasted 170k with no problems before a LIM failure did it in.
 
Commercial octane boosters are a rip-off. Most will say "Raise your octane 3 points" or something like that. They are implying that your octane will increase from 91 to 94. 3 points right? Not so. A point is .1 so three points is 91.3 octane. Hardly worth the price in my opinion. Keep away from lead but you can make your own real cheap and get some real use out of it. Here are a few recipes that I've copied over the years.

Keep in mind that more is not always better. You'll just want enough octane booster to stop your KR. Any more than that could hurt performance. There's not as much energy in 94 octane gas as there is in 89 octane. Typically all higher octane gas does is slow down the combustion rate. That's why it's probably best to run what the manufacturer says to run.

Good Luck

Toulene
R+M/2...114
Cost...$2.50/gal
Mixtures with 92 Octane Premium
10%...94.2 Octane
20%...96.4 Octane
30%...98.6 Octane
Notes: Common ingredient in Octane Boosters in a can. 12-16 ounces will only raise octane 2-3 *points*, I.e. from 92 to 92.3. Often costs $3-5 for 12-16 ounces, when it can be purchased for less than $3/gal at chemical supply houses or paint stores.
​
FORMULA 2
Xylene
R+M/2...117
Cost...$2.75/gal
Mixtures with 92 Octane Premium
10%...94.5 Octane
20%...97.0 Octane
30%...99.5 Octane
Notes: Similar to Toulene. 12-16 ounces will only raise octane 2-3 *points*, I.e. from 92 to 92.3. Usually mixed with Toulene and advertised as *race formula*.


MAKE YOUR OWN OCTANE BOOST How to make your own octane booster (this is the basic formula of one of the popular octane booster products). To make eight 16 ounce bottles (128 oz = 1 gal):
100 oz of toulene for octane boost
25 oz of mineral spirits (cleaning agent)
3 oz of transmission fluid (lubricating agent)

This product is advertised as "octane booster with cleaning agent *and* lubricating agent!". Diesel fuel or kerosene can be substituted for mineral spirits and light turbine oil can be substituted for transmission fluid. Color can be added with petroleum dyes.
 
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1963SS said:
Keep in mind that more is not always better. You'll just want enough octane booster to stop your KR. Any more than that could hurt performance. There's not as much energy in 94 octane gas as there is in 89 octane. Typically all higher octane gas does is slow down the combustion rate. That's why it's probably best to run what the manufacturer says to run.
Click to expand...

Not exactly true. Higher octane retards combustion, allowing more compression, which in turn delivers MORE energy upon release (ignition).

"Premium" gas in the US is defined as 91 octane, yet the majority of the gas stations in the Mid-Eastern states carry 93, some even 94. While there IS a limit how much octane you can use before you see a decrease in performance, unless you are putting in straight toluene or something you probably won't reach that maximum in a modern vehicle.

Exceptions exist obviously. Case in point, my 2007 Ninja has carburetors, with a 2 stage, RPM based timing. Putting in anything other than 86-87 octane makes it run like crap, because it doesn't have anyway to adjust for the higher octane.
 
Wow, thanks! Lots of good info. Earlier I was under the hood looking for my next project....true cold air... that'll help with KR! Anyone here bend up a box around their cone filter? I'd post a pic of my setup but I just haven't figured out how yet. The basis for all of this is that I noticed going from warmer days back to cooler days this spring the performance of the car is unusually predictable based on ambient air temp differences just from 55 to 70 degrees. I watched a HP show recently where they routed the intake pipe down near the drivers side fog light (between the nose and inner fender). After looking under the car it seems their is a great area that would stay dry under most circumstances. Anyone tried something similar?
 


Seems a cold air intake doesn't do much on a GTP because the temp increases a LOT after the compression. Need an intercooler between the SC to really lower intake temps.
 
Use e85 mixed with your gas. Not only does it clean it also alleviates alot of KR without destroying o2 sensors etc.
 
I'll look up that CX racing fender well now!

E-85 is not prevalent here in Idaho so for now i'll think old fashioned about additives.
 
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Whats the take on plug heat range for the mods I have? Pretty sure mine are stock. Not sure how much effect that could have on KR

Is the filter box write up on this site? a search didn't give it up. i'll try again after confirmation
 
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