"HEET" fuel additive

[Corvette95]

I am only able to get 90 octane ethanol free gas here in Alabama. Fuel injectors have been upgraded and I know I "can" run regular gas but I choose not to. I let my cars sit between drives longer than I like. I bought a case of HEET for use as an octane booster, I tried to search the actual make up of it but didn't get any good information. Anyone here use HEET and if not, what would be a good safe octane booster that won't turn the fuel bad after sitting. Thanks!

[BigJohn]

Alcohol

[spork2367]

And there are two formulas. Yellow bottle is methyl alcohol, red bottle is isopropyl alcohol.

[Paul Workman]

Adding HEAT to the fuel is akin to making your own ethanol! HEAT IS alcohol, and too is much of my favorite additive - Sea Foam. (The latter is advertised to keep injectors free of any sludge built up.)

That said.... If you're gonna add HEAT to the fuel, might as well put ethanol in the tank in the first place and save the money. OR, simply b/c the jets on one of my six carbs (Honda Valkyrie) wound up with clogged jets as result of shutting off the gas and running the engine till the carbs were "empty" resulted in the jetting being filled with precipitant of...Sta-bil?

My small engine mechanic (that services my generators and other 2 & 4 cycle equipment when I don't have the time (or parts!) to do it myself) vehemently insists on avoiding Sta-bil (@ least if you're gonna run the carb dry before storing over winter). He claims the stuff will suspend whatever impurities are in the tank which (apparently) will precipitate out and coat the surfaces and the jets when fuel is allowed to evaporate. Instead, he recommends Sea Foam.

A lot of ppl use both Sta-bil and Sea Foam and have no issues with either. Personally, I have never had an issue with either as long as the cab jets were immersed the whole time the engine was in storage. I've never had a storage issue as long as the tank was full up with fuel (including ethanol, here in IL). For good measure, I do use Sea Foam in my stored yard equipment...just because of the TWO TIMES draining the fuel that was treated with Sta-bil and storing over winter resulted in plugged jets come spring. Was it the Sta-bil or the precipitants left when the fuel evaporated - regardless of Sta-bil? IDK.

Bottom line: I fill the tanks plum full in the fall - add a dash of Sea Foam "just because", and don't worry about it! (knock on wood) it has worked for the last 15 winters w/ no issues like I had the first 5 years I lived here.

Not very scientific, according to formal scientific methodology, but hypothetically keeping the tank filled to eliminate possibility of substantial condensation...seems to be working. YMMV!

[Corvette95]

I am a believer and user of Sea Foam, my HEET is the yellow bottle. I just want to add 1 to 2 points of Octane.

[PhillipsLT5]

Have you contacted VP?
VP SOUTH
50 Rosser Circle Huntingdon, TN 38344
T: 706 995 6122
F: 706 335 3358
vpsouth@vpracingfuels.com

[PhillipsLT5]

From Hib

Octane booster threads are like oil threads...they can get pretty partisan.

I've spent a lot of time testing boosters–at least three separate instances–and found that, in fact, some of them work fairly well at boosting the octane of premium unleaded pump gas a modest amount.

The thing to remember about the pour-in boosters which actually work is that there are some downsides to them.

First, any pour-in booster capable of a practical increase in octane has "methylcyclopentadienyl manganese tricarbonyl" or MMT as the active ingredient. That additive was developed by the Ethyl Corporation after tetraethyl lead (TEL) was outlawed back in the day. Today MMT is produced by Afton Chemical a subsidiary of the NewMarket Corporation which also owns the Ethyl Corporation.

Secondly, all octane boosters are more effective with lower octane fuels than they are which higher octane fuels. When you see some of the amazing claims some octane booster suppliers make like "Will raise octane five (six, seven or eight) numbers", invariably, that data comes from mixing the booster with regular unleaded gas which will is 85-87-octane rather than premium unleaded gas which is 91-93 octane and sometime 94-oct.

Thirdly, some octane booster vendors will claim their product increases octane a certain number of "points". Few consumers understand the difference between octane "points" and octane "numbers" and that difference is a factor of ten, ie: an octane "point" is a tenth of an octane number. There are some boosters which claim they can raise octane x points. When you read that, remember that's tenths of an octane which means they are of little use.

Fourth, when MMT is combusted it leaves behind hard metallic deposits on combustion chamber walls, piston tops, valve heads and spark plugs, thus, in that respect, it's no different than TEL and may be somewhat worse. That means that long term use of MMT boosters may cause plug fouling and other problems typical of hard metallic deposits on engine parts exposed to combustion.

Fifth, byproducts of MMT combustion degrades catalytic converters. The degree and the speed of the degradation will depend on how much MMT is in the fuel mix. Eventually, the cat will no longer effectively catalyze the exhaust and will become restricted.

Sixth, in some cases–like right now with gasoline prices tanking–the cost of regular use of MMT in concentrations high enough to raise octane to the appropriate level (which depends on the engine configuration and the calibration) are more expensive than mixes of premium unleaded pump gas and 100-oct unleaded racing gas.

While I have tested several, I never use an MMT octane booster long-term because of the above. As to what brands I have tested and found them to work. One is Driven Racing Oil "Defender + Booster" and the other was the now-discontinued NOS "Racing Formula".

Lastly, if you're going to insist on using an MMT booster on a regular basis, I'd do some testing using a scan tester which can save "snapshot" data. You need to set up the scanner to read knock retard then make some test runs with just gasoline and record KR. Then switch to your chosen concentration of octane booster and run the test again. Use only enough booster to counteract knock retard. In fact, when I did my first test of the NOS octane booster back in the late-90s, I used Barney, the '95 I used to own and that's how I figured the proportion to use. That said, after the testing was complete, I never used an MMT booster again in Barney because when I removed all the plugs and pulled the cats for inspection, I could see the orange deposits typical of combusted MMT.

Other than those tests, when I need to raise the octane of the gas I run on my Corvettes, I use Rockett Brand 100 Unleaded racing fuel.. Usually, it takes a mix of 1:3 or 1:2 of Rockett Brand and pump gas to get to where I am either KR-free or the KR is way low. The only exception to that is my '19 ZR1 which required a 1:1 mix to get rid of the 2G LT5s rampant KR.

If you want to learn more about gasoline for higher compression engines in Corvettes, a number of years ago I wrote a tech. article on octane boosters and racing gas for a couple of different magazines. Later I did a revised version for the Corvette Action Center. Admittedly at this point in time, there are parts of that story which are a bit dated, but the majority of the information still holds true.
__________________
Hib Halverson
Technical Writer
former owner 95 VIN 0140
current owner 19 VIN 1878

[spork2367]

To answer the original question briefly; 10% isopropyl alcohol will get you from 92 to 94.5ish. They don't recommend any more than 10%.

[Paul Workman]

AND...there have been several articles on E85 and octane advantages of its use. I don't use it, even tho the F250 will run on it.

Anywayz...just another place to look regarding alcohol to the fuel.

[Zman]

Having 7 C4 ZR1s and only 91 octane available. VP Octanium! Call me stupid! People are opinionated......Some are experienced.