Octane Ratings Explained

The octane rating of gasoline is a standard measure of performance for engine fuel. The higher the number, the more compression the fuel withstands before it ignites. Fuel with higher octane numbers are harder to ignite. Higher octane fuel is also mostly costly; thats why the ‘premium’ fuel you see at the gas station has a higher octane rating.

A high octane will prevent engine knock, which happens when a separate pocket of fuel and air ignites after the main combustion in the engine has already occured. This can damage the engine and is preventable with proper octane rated fuel. High octanes will allow higher compression ratios, which is directly linked with engine efficiency.

This video explains exactly how efficiency (and performance) can be improved by increasing the compression ratio:

Octane Boosters: Do they really work?

A commercial octane booster helps make this internal combustion process flow more smoothly, eliminates carbon build up and makes your engine more efficient. Octane boosters are an additive that reduces the gasoline volatility to make it harder to ignite. Generally, you’ll want to use octane boosters when you have an engine with a high compression ratio to prevent the engine from pre-igniting. Most normal cars have engines with low compression ratios of between 8.5-9.5 to 1, which work fine with regular unleaded fuel, but if you have a supercharged engine, you may want to invest in octane booster.


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Our Pick For The Best Octane Booster

Unlike most products on the market, ..
$30 on Amazon


Unforunately, many commercial octane boosters fail to impress customers. It’s important to manage expectations- octane boosters are not some magic fluid that will super-charge your car. Rather, it will increase your measured horsepower and engine efficiency by a few percentage points- useful if you care about getting the last few drops of performance out of your vehicle (such as if you like to race).

A max racing octane booster may raise octane numbers by 6 full octane numbers up to 60 points, when used at highest recommended dosage- meaning 91 becomes 97 octane fuel. Pretty good if u ask me, And most people don’t have the compression to take full advantage of that octane rating anyways. I have used it in a Harley with 11.3:1 compression and notice the difference in throttle response and power.

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A handful of octane boosters can really make a difference. This guide will show exactly which ones they are.
This is a very common thing with premium vehicles such as BMW’s, Mercedes, some Nissans, and a whole bunch other above average vehicles.

We’ve put together a list of the best octane boosters that are current available for the public to purchase. While there’s a few dozen brands advertising “10,20,30, 40 etc number boost” which sounds impressive, but when you narrow it down, these numbers only mean 1,2, 3, maybe 4 octane levels of boost.

The products recommended below are proven to work in boosting current octane levels (by various levels), no compromises here. Take a look…

MAIN CONSIDERATIONS FOR OUR TOP RATED OCTANE BOOSTERS

PERFORMANCE

Looking at an given octane booster, you’re looking at one MAJOR aspect, and that’s by how much does it boost. Being the most important factor of any octane boosting product, we’ve listed for each recommended product that true level of octane boosting you’ll be able to achieve.

Keep in mind in our NOTE above, showing you that for each 10 points is 1 octane level.

COST

Octane boosters can add up quickly when using them for heavy duty applications. Whether you are racing, or simply getting your current vehicles octane level where it’s supposed to be. The cost associated with using each octane booster is taken into consideration, and is a big factor in whether you should or should not make the purchase.

Royal Purple 11757 Max-Boost Octane Booster and Stabilizer

Royal Purple Max-Boost – 16 Ounce Can is a high-performance octane booster with fuel treatment that increases gasoline octane, reduces emissions, and enhances engine performance while stabilizing fuel. Max-Boost is formulated with MMT, which delivers the best octane enhancement to help eliminate engine-damaging detonation, pre-ignition, and pinging or knocking from low octane gasoline. Max-Boost is formulated for engines equipped with carburetors, port fuel injection and direct injection, as well as turbocharged, supercharged and nitrous-injected engines. Safe for use in leaded and unleaded gasoline’s, and alternate fuels like gasohol, reformulated gasoline, and all ethanol blends. Max-Boost is safe for oxygen sensors and catalytic converters. Performance engine oils contain higher levels of phosphorus as an anti-wear additive, which can accumulate in catalytic converters and reduce their effectiveness. Max-Boost protects against phosphorus poisoning of catalytic converters.

Question: How much do you use on 10.5 gallon tanks and does it have any ingredients that may void the warranty on new vehicles?
Answer: In one of the other answers they tell the ingredients. I also look at the Royal Purple website. Sometimes they have more information about their products than what is listed on amazon. 4 years ago I had some questions I could not answer by reading everything available so I called them and I was able to talk to someo… see more
By phil on June 12, 2016
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Question: Anyone ever used this in an rx8 with a lower than recommended fuel octane.
Answer: No, but I highly recommend it for any gasoline motor. Actually I would recommend the proper octane fuel, but if that can’t be purchased in your area this would be a good alternative. Remember true octane booster only comes in metal containers, octane boosters in plastic containers don’t actually boost octane.
By Amazon Customer on February 15, 2016
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Question: Can this product be used together (both poured into your gas tank at the same time) Max clean 20 oz. Fuel Cleaner and Stabilizer? And should it?
Answer: It is perfectly safe to use Max-Boost and Max-Clean together in one tank. In fact, there is a synergistic effect on the cleaning provided when both products are used as directed in the same tank of fuel. Be aware that Max-Clean is recommended to be retreated up to every 10,000 miles. Max-Boost would have to be used … see more
By RPoilAddicted on April 16, 2015 SELLER
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Question: Is it safe on 2stroke outboard motors?
Answer: Yes, but RP also carries HP 2-C designed spacificly for two stroke. Royal Purple classifies both products for Marine use as well as 5 other products check out their site.
By Amazon Customer on May 27, 2016
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Question: is this product oil base or liquid fuel base?
Answer: Hello Arnold!, this is a gasoline/fuel additive and it mainly contains Methylcyclopentadienyl manganese tricarbonyl
By Harold on March 2, 2016
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Question: How much fuel does a 16 oz bottle of Max-Boost treat?
Answer: I would like to think you can get optimum performance out of 22 gal and under. I’ve used it myself and I drive 2013 Silverado 1500 Z71. In fact, I use nothing but royal purple products. They are top notch.
By Yung_Munny3k on June 30, 2015
picked up a bottle at my local part store and added about half a bottle to a little under a half tank of fuel in my 2003 f150 4.6 with a fue mods ( cold air intake,75mm throttle body, headers, accell coils, sct programmer, electric fans, and duel exhaust,) and I can say for sure my truck runs way better with this booster in the fuel.i keep my truck on the preloaded 93 octane tune and I can tell a HUGE difference.maybe the fuel im getting local isn’t true 93 with 10% corn but this has done the trick to makeing my teuck feel and peform like I have felt like it should.and scene this is the only thing I have dont different in the last few months im betting thats this booater really works.
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5.0 out of 5 starsGreat for summer use with only 91 octane gas availability
By Comp Expert on July 10, 2016
Verified Purchase
For those that have performance vehicles, but only 91 octane gas as the highest selection in your area, and live in 100+ degree summer temps, this product is for you. Problem with 91 octane is that at some pumps it might only be 90.5 and you never really know it. In fact, it will rarely actually be at 91. Unfortunately, if your car is tuned for 91, this means you already have compromised gas so you’re not making full horsepower. Putting in this booster will compensate by increasing the octane average and lead to far less timing pull during very hot weather. I noticed the results during full throttle runs, much less power loss when the thermometer starting cranking upwards.

Now with that said, if you have a “regular” tuned car with 87 you don’t need to buy this. Just routinely gas up with the next higher grade from time to time. And if you’re lucky to have 93 offered, you don’t need this either (unless you’re running a custom tune for something higher).
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5.0 out of 5 starsPower feels better at midband
By Matt on August 4, 2016
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This went into my 2002 SPI Ford Focus and the idle became smoother with less hiccups. Power feels better at midband, and maybe a few hp improvement. Online videos show this product does remove some deposits from combustion chamber. It gave me the result I was expecting. I am happy to recommend the product from my own experience.
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5.0 out of 5 starsroyal purple made the biggest difference and work perfect for my application
By Justin DeVincentz on February 14, 2016
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Well it’s royal purple. I recently put a different tune in my 04 Dakota 4.7 and with the need for higher octane than I can get at the pump I tried a few different octane boosters and out of all of them, royal purple made the biggest difference and work perfect for my application. I should have just tried rp first because I use royal purple produst in every part of my truck.
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5.0 out of 5 starsMakes a big difference
By slimpie on July 5, 2016
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I was skeptical about the these types of products and decided to try it on my 1999.5 Audi A4 1.8 Quattro. The turbo engine always has had a hard time with Texas heat and humidity. When I had the opportunity to drive the car at Circuit of the Americas I put this in the tank before filling up. It makes a big difference. Normally the car feels sluggish due to heat soak at temps above 95F and it feels as if the turbo is broken. With this product the car drives as if the temp is in the 70s with very good throttle response and no more sluggish feeling. Will keep on using this in the summer time.
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5.0 out of 5 starsSurprisingly seems to free up some power in my BMW …
By Shreck on April 18, 2015
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Surprisingly seems to free up some power in my BMW 530i and Honda Fit motors. Definitely took care of valve rattle in the BMW.
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5.0 out of 5 starsWorked for me!
By Erin R on May 7, 2016
Worked great on my 2003 altima v6 w/ 183000 miles. Car made a slight tick when first would start the car, now after adding the royal purple – it seems to have lubed up whatever was sticking or clicking.
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5.0 out of 5 starsRoyal Effectiveness!
By I4Y on July 6, 2016
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It’s effective as long as I don’t pour the entire bottle per each tankful. That has been my mistake all along. My car is tuned so when it seems to apply more timing advance is when I use only 1/4 of its content per half tank of gas or 1/2 of the booster per tankful. This is good for me to know because I don’t end up wasting it right away.

Lucas Oil 10026-PK12 Octane Booster – 15 oz (Pack of 12)

I drive an 07 Acura TL 3.2 and have just put a bottle of Lucas Octane Booster with a full tank of Chevron 92 premium gas. I have used Royal Purple Max Boost, 104+ Maximum Formula, Oreilly’s octane booster and Turbo 108 Octane Boost. What I’ve experienced is that 104+ Maximum Formula felt the best performance, second is the Royal Purple Max Boost and slightly behind the Royal Purple Max Boost in third is the Lucas Octane Booster. In fourth place would be the Turbo 108 Octane Boost, last and not worth the money would be Oreilly’s octane booster. I will be trying Klotz Octane Booster and Torco Accelerator next. If any of those are not worth the money, I would just spend my money on 104+ Maximum Formula from then on.

use a bottle of this with EVERY fill-up on my 2006 GTO supercharged @ 8 lbs. boost. Without this i cannot accelerate with WOT. This stuff is GREAT!! I have already used 5 cases (60 bottles) and have had no adverse reaction on my sensitive O2 sensors or Catylytic converters. I will keep using it.
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4.0 out of 5 starsJust be aware, it uses MMTs not street legal
By Sandman on July 28, 2013
This product DOES contain manganese fuel additives MMTs (hence why it says on it, not street legal). Email, Lucas oil if you question the MMTs comment. So be careful if your car is under warranty. It can be harmful to certain cars sensors. I use it in older car and does work very well. However, Acura warns against it use.
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4.0 out of 5 starsStuff really works
By bonanza on July 28, 2011
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I’ve tried many octane boosts for my high compression Harley Davidson, and none have worked except Lucas High Octane Boost. Quits the pinging on acceleration, high heat or climbing. Seems to run better also. A must buy!
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5.0 out of 5 starsIf 93 octane is not available, this is your BEST BET!
By Leo Cheng on January 10, 2014
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I have a 2013 BMW M3, and the motor is optimized for 93 octane gas like most Euro sleds. But guess what, I’ll probably never see 93 octane gas here in So. Cal, until then, this octane booster is my best bet.

The difference is big enough that within a few miles of driving after a bottle is added, the ECU in my car adjusts its mapping and added power can be felt through out the rev range.

Most auto parts stores want $9.99 a bottle where I live, save your some money and get this from Amazon!
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5.0 out of 5 starsOctane Booster that works!
By Prochargedstang on November 8, 2013
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Did not let tuner know I had this in tank when I was getting my car dyno tuned. I received a phone call asking what gas I had in gas tank because they were able to put a lot more timing into my car without experiencing any detonation.
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5.0 out of 5 starsLucas oil octane booster
By Don F–Los Angeles on June 28, 2013
Verified Purchase
An excellent product which I use with every tank fill up. The car seems to have more pep and there is a mileage increase. You notice the difference when you forget to put it in. For further performance I combine the octane booster with Lucas fuel treatment (6 0z octane booster with 10 oz of fuel treatment) –my tank holds 14 gallons. The combination keeps the injectors clean. This is important because the injectors do clog up and mpg and performance declines. Take it to the dealer and you will pay hundred of dollars.
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5.0 out of 5 starsLucas Oil 10026-PK Octane Booster
By Buddy G. on November 16, 2012
Verified Purchase
I used this product in my 1970 Dodge Challenger 440 six pack and i was very pleased with the results as with sunoco ultra i would get pinging and adding Lucas Octane Booster i was able to advance my engine timing to
where it should be without pinging,i had tried other octane booster products before without success,Lucas is the
best!



104+ 10406 Octane Boost

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Torco Accelerator 32oz

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Torco has made a reputation as a top-notch manufacturer of race fuels, which is already sufficient reason for you to have it considered above other models that are available in the market. They know how to achieve optimal performance of your engine, providing you with the assurance of its effectiveness.

With the use of this product, the octane of your fuel can be raised to as much as 105, which is pretty much impressive when it comes to what is claimed by other manufacturers. It can result into greater horsepower and efficiency, which are exactly the reasons why you will be using an octane booster in the first place.

Versatility is another reason why this product stands out from all others within the competition. The blend can be customized based on individual needs and preferences. You will have completed control on how it can be used.
Even if you have a sensitive engine, this octane booster will not cause any harm. As shared by the people who have already used this product in the past, catalytic converters and O2 sensors will not be damaged, regardless of how sensitive they can prove to be.


RACE-GAS Race Fuel Concentrate

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Blue Magic NA30-12PK Turbo 108 Octane Boost

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Klotz Octane Booster

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This octane booster comes in a one gallon packaging, which is better than many others that are smaller in size. One thing that we loved about this octane booster is that it is made from 100% pure synthetics. There are no chemicals that are used in its production.

It is also excellent when it comes to compatibility, making it useful in a wide array of applications. It can be blended with oils and lubricants, even if they are subjected to high temperatures. They can also be mixed with petroleum oils, synthetic lubricants, and gasoline.

This octane booster is made from concentrated tetraethyl lead substitute, a premium formulation that can improve the octane rating of petrol by as much as 10 numbers, which is equivalent to 100 points. With the use of this octane booster, the negative impacts of spark knock and engine detonation can be alleviated.
Octane boosting is not the only benefit that can be achieved with the use of this product. Taking a look at the octane booster reviews that have been shared by its users, we also conclude that it can be effective in providing lubrication to upper cylinder. This makes it beneficial in more ways than one.

To explore the impact of fuel quality on engine performance, we stuck a 10.4:1-compression-ratio 360 Mopar on the DTS dyno at Joe Jill’s Superior Automotive. Then we beat it up, making 40 power pulls to see if octane rating has a significant impact on power and if ignition timing can be effectively manipulated to ward off detonation without heavily penalizing output. Does fuel additive really increase the octane of pump gas? And does boosting the fuel’s octane really make more power on a typical street engine? The results are surprising.

87-Octane Unleaded: 396.0 hp/401.3 lb-ft

You pull up to the pump in your hot street whip; the needle’s on E. You’ve only got 20 bucks, and you have to make it count. Premium is 30 cents a gallon more expensive than the cheap stuff. You roll the dice, grab the nozzle marked “Regular,” and start filling.

Approximating this scenario, we filled our 2-gallon fuel cell with a dose of 87 octane and set the total ignition timing at 31 degrees BTDC. Despite the sleazy gas and heavy dyno loading, the smooth power curves indicated no sign of detonation. Then we tried 34 degrees and still no sign of detonation. Yet another counter-clockwise twist of the Accel Billetproof electronic distributor gave the Mopar 36 degrees total; despite the lousy gas, the motor liked the additional timing.

Could it take more? Pushing the envelope further, we dialed it up to 38. Detonation had found us. The most telling evidence of detonation was seen in the 300-rpm drop where peak horsepower was made and in the way the smooth power curves of the previous tests had become a jagged mess at 4,200 rpm all the way up to our self-imposed 6,000-rpm limit. The peaks and valleys on the dyno chart reveal uncontrolled combustion causing fluctuations in peak cylinder pressure and, as a result, hiccups in the force delivered to the business end of the crankshaft. See Test 1 in the sidebar below.

87-Octane Unleaded With 104+ Octane Booster: 397.9 hp/403.1 lb-ft

The rent is due and the kid needs new sneakers, so you’re running the cheap stuff… again. You add one 16-ounce bottle of octane boost to your 20-gallon tank, cross your fingers and hit the road.

To see if we could turn sow’s-ear 87- octane into silk-purse go-juice, we shut off the dyno’s fuel pump and let the test motor drain the Edelbrock 750’s bowl dry at idle. Then we added 2 ounces of Super 104+ additive to the 2 gallons of 87 in the fuel cell. With timing set at a conservative 31 degrees, we saw no appreciable difference, but we’d only just begun. Twisting the sparker up to 34 degrees BTDC delivered 6 hp, and we were still far from the motor’s likely detonation zone. At 36 degrees we noted that more peak horsepower was made at a higher engine speed, a clear sign that the chemical enhancement was keeping detonation at bay. Further proof of the benefit came when we cranked it well into what should have been rattle city with 38 degrees of timing. Power readings were on their way down due to mechanical factors related to the efficiency limits of the heads, cam, and induction rather than fuel quality. Despite this, the motor still made peak power at 5,800 rpm, a full 400 rpm more than without booster. Convincing proof that the Super 104+ was thwarting detonation.

If some is good, then more must be better, right? Doubling the dose of octane booster to 4 ounces in the 2-gallon fuel cell (like putting two 16-ounce bottles in a 20-gallon tank), and leaving the timing set at 38, we gained 1.5 hp. While power wasn’t improved significantly, the 5,700-rpm horsepower peak and smooth torque and horsepower curves indicated continued protection against abnormal combustion. Octane booster works, but double-dosing an engine like ours wasn’t worth the added expense. See Test 2 in the sidebar below..

91-Octane Unleaded: 402.1 hp/409.4 lb-ft

The bills are paid and you’ve got a few extra coins rolling around in your pockets, so you give your motor what it should have had in the first place—the good stuff: 91 octane.

While some parts of the country can brag about as much as 94 octane, left-coasters must make do with 91. With the timing set conservatively at 31 degrees BTDC, the sturdy 360 surpassed the best 87-octane numbers by 2 hp and 5 lb-ft. At 34 degrees, the numbers dipped, but recovered when we bumped timing to 36 degrees, delivering our highest numbers yet and breaking the 400hp mark.

There was no doubt that the higher octane fuel was good for a few extra ticks on both the torque and horsepower charts, but would it finally allow us to advance timing to 38 degrees BTDC without losing power? No dice: At 38 degrees, the numbers fell by 8.2 hp and 11.9 lb-ft, illuminating the reality that there is a difference between chemical potential and mechanical potential. If testing reveals that an engine is most efficient with timing set at 36 degrees BTDC, it will not necessarily produce more power even if high-octane fuel allows the use of more ignition advance. Still, our testing was far from over. See Test 3 in the sidebar below.

91-Octane Unleaded With 104+ Octane Booster: 399.8 hp/403.6 lb-ft

You’re off to the local bracket races. You know your pump-gas motor will be flogged pretty hard, so for insurance, you pour a bottle of octane booster in the tank and roll into the staging lanes.

Once again, Jill shut off the dyno fuel pump and let the 360 idle itself dry. Then the customary 2 ounces of Super 104+ were added to 2 gallons of 91-octane, and the torture test resumed. Starting again at 31 degrees of timing, the motor dropped a few points. It recovered some ground at 34 degrees, and just like the other tests, made best power at 36 degrees total. Going further, we advanced timing to 38 and lost a little more power; double-dosing the booster with the timing set at 38 brought a slight improvement. The power numbers generated with the boosted 91-octane are lower than those made with non-boosted 91, an indication that the fuel additive may have slowed the burn speed and reduced cylinder pressure. One thing is certain, there was no detonation present or we’d have seen it on the dyno charts and in reduced peak crank speed numbers. See Test 4 in the sidebar below.

100-Octane Unleaded: 403.5 hp/407.5 lb-ft

You’ve heard some of the local street rats whisper about 100-octane unleaded being sold straight from the pump. Its like some flashback to the ‘60s, but is it too good to be true? You just have to try some.

Even though we were pretty sure detonation wouldn’t be a problem with so much octane coursing through our 10.4:1 360’s veins, we began with the 31-degree setting to maintain consistency and to see if any noteworthy patterns emerged.

The dyno video monitor flashed just over 400 hp. Moving up to 34 degrees BTDC delivered virtually identical results, and 36 degrees bought almost 3 hp while torque remained nearly constant. At 38 degrees, the numbers were largely unaffected. The motor seemed indifferent to the increased timing, but in contrast to previous cycles run using the lower fuel grades, the amount of power sacrificed with timing set at 38 was negligible. To see if more timing would translate into more power, we did the unthinkable and moved up to 40 BTDC and let it rip. The results amazed and confounded us. Testing thus far confirmed that this particular motor combination really liked 36 degrees total, regardless of fuel quality. Any more or any less cost power—not much, but the numbers consistently fell. But now with 100-octane, the power seemed to remain stable despite the substantial 4-degree jump in timing. What’s more impressive is the fact that the 100-octane fuel was the only grade tested thus far producing maximum torque and horsepower numbers that never fell below the 400 mark. Our conclusion was that octane was not the sole factor at play, and that the 100-octane had superior burn characteristics to the MTBE-laden pump gas available here in California. See Test 5 in the sidebar below.

114-Octane Leaded: 408.3 hp/414.7 lb-ft

You love to watch professional drag racing on TV and jump with joy when the Pro Stockers run. So why shouldn’t you also jump at the chance to run the very same gasoline in your hot rod? It’s gotta run faster, right?

Taking our motor through its now well-established paces, we rang up our highest numbers yet at the 31-degree setting. We couldn’t wait to get to the 36-degree sweet spot, but exercised restraint and followed the plan, dialing in 34 degrees. What? Power was dropping? A backup run at 34 BTDC confirmed it. “Gotta be some kind of fluke. We’ll get it all back and then some at 36 degrees.” Or so we thought. We saw another drop at 36 degrees, and crumbs of no significance at 38 degrees. Through it all there were no signs of detonation. To rule out the possibility of error, we restored the timing to 31 degrees and watched the output jump back up to 406.6 hp at 5,700 and 413.7 lb-ft at 4,500. Further exploring the apparent benefit of retarded timing, Jill cranked in a mere 29-degree setting and output began sliding downward, losing 5.1 hp and 4.2 lb-ft. Why hadn’t more timing increased power? Probably because the 114 had even better burn characteristics than the 100. Its hydrocarbons vaporized and burned more readily, releasing energy sooner and accounting for why it required less spark lead to reach complete combustion. The octane level was not the operative here—rather it was the superior hydrocarbon content and vaporization characteristics of the racing fuel. See Test 6 in the sidebar below.

Conclusion

Frankly, the results of our test were a bit confounding. We consulted the chemists at Super 104+ and our pal Tim Wusz at 76 to help figure out what had happened. Here’s what we learned:

First, the octane booster did work. However, we saw that octane alone does not deliver horsepower; it only allows more complete utilization of the hard parts in the engine. Wusz said, “An engine does not know what the octane rating of the fuel is, unless it is too low”; note that we made less power by adding booster to 91-octane fuel. The lower the octane of the base fuel, the more benefit you’ll get from octane booster.

Also, the Edelbrock heads on our test motor have high-efficiency combustion chambers that are very tolerant of low octane levels, and their aluminum construction helps, too. Older chamber designs may not be as efficient and may succumb to abnormal combustion more easily.

But most of all, we discovered that our presumption that higher-octane fuels burn slower than lower-octane fuels (and therefore require more ignition lead) is largely incorrect. There are too many other fuel-formulation issues at work to assign a general rule about octane. Race fuel tends to have a more powerful formulation than pump gas, regardless of octane rating, because it is denser and can release more power and heat. (Note that we made the best power with 114 octane with the least ignition lead, indicating it had the fastest burn time.) California pump gas is blended with methyl tertiary-butyl ether (MTBE), alcohol, and other ingredients damaging to performance. Knowing what we know now, we’ll always experiment with ignition timing—both higher and lower settings—when we change fuels rather than presuming that more power can be made with more octane due to more timing.