DRP Articles
Tech Tips: Aviation Gas vs Racing Gas
Saturday, 10 February 2001 08:00

Tech Tips: Aviation Gas vs Racing Gas

Legal Stuff: Any Damage that results from using or employing any of the tips outlined below are NOT the responsibility of Drag Racing Pinoy. Use the tips with caution. You are responsible for any damage or injury that may occur. Use caution at all times!

written by, and thanks to
Tim Wusz
76 Products Company

I am going to attempt to address the controversy of aviation gasoline verses racing gasoline for use in race cars. Some racers use aviation gasoline which is fine for some applications but does have shortcomings. There are several grades of aviation gasoline (avgas) that we must identify before going any farther.

1. Avgas 80/87: this product is used in low compression ratio aircraft engines, contains little or no lead, is red in color, and should not be used in any automotive engine due to a low motor octane number of about 80.

2. Avgas 100/130: this product that can be used in some automotive engines. It has both research and motor octane numbers slightly over 100. Avgas 100/130 is green in color, contains four grams of lead per gallon, and is becoming harder to find.

3. Avgas 100 LL: the LL stands for "low-lead" which means two grams per gallon, low compared to the avgas 100/130 that it was designed to replace. It has research and motor octane numbers very similar to the 100/130 product previously discussed. The color is blue. This product sometimes has a high level of aromatics which can contribute to lazy throttle response and dissatisfaction of the consumer.

4. Avgas 115/145: this product was developed for high performance piston aircraft engines used in world war II and in the Korean war. It is very hard to find anymore due to lack of demand although it is of very high octane quality. The color is purple.

The remainder of this discussion will assume that our basis for comparison with racing gasoline is avgas 100/130 and/or 100 LL since they are both available and have acceptable octane quality for limited applications. When the word "avgas" is used, it will refer to avgas 100/130 or 100 LL.

Avgas is less dense than most racing gasolines. Instead of weighing about 6.1 to 6.3 pounds per gallon like racing gasoline, it weighs 5.8 to 5.9 pounds per gallon. The racer must compensate for this by changing to richer (larger) jets in the carburetor when changing from racing gasoline to avgas.

The other major difference is octane quality. Avgas is short on octane compared to most racing gasolines. Many racing engines with "quick" spark advance curves or with no centrifugal advance have more spark advance at low rpm than avgas and some racing gasolines can handle. The result is detonation, especially during caution periods in circle track racing because all of the spark advance is "in", rpm is low, and part throttle air fuel ratios are too lean for the operating conditions. If the driver does not "work" the throttle back and forth, pistons can be "burned" which melts away part of the aluminum piston material. Inadequate octane quality is one of the quickest ways to destroy an engine. Pistons can be severely damaged during one acceleration where detonation is present and the racer may not know what is happening until it is too late.

For maximum performance and power from a racing engine, racing gasoline will normally provide better performance than avgas. Avgas can be a good gasoline for some applications, but since most racers do not know the octane requirement of their engines, they would be better off with a "real" racing gasoline that will give them the overall resistance to detonation that they need to protect their investment. If someone has spent from $15,000 to $50,000 or more on their racing engine, it is foolish to cut corners on gasoline be sure you have a gasoline with adequate octane quality.

Steve Jack
Southeastern Goodguys Rep

As an avid hotrodder and aircraft mechanic, I dispute what you have been told about AVGAS! First, the octane rating for the avgas that you mentioned is much higher than used in general aviation for the most part, so my first question is who or what told you that? I really question the validity of the octane rating. General avgas has a 100LL rating....not enough for 12 to 1 race motors I might add.

Secondly, the first part is moot because AVGAS has a different specific gravity than that of regular gasoline or racing gas for that matter. With this in mind what happens is the avgas leans out your engine tremendously and is really formulated for a whole nother purpose and certainly doesn't have the BTU content of pump gas...a real problem for everyday driving! Simply put..I don't recommend it and most avgases are only good for up to 11.+ CRs (mechanical) in cars anyway even if you jet them correctly. I suspect(I know) that the combination of not being the octane that you though it was, plus creating a lean condition is what sent your engine hammering down the street.

Now, having said that I will tell you a dirty little secret of Racing Fuel. The only difference between racing fuel and pump gas is TOLUENE! Yep, I said toluene!!!!!!(and a little bit of xylene, but it's insignificant here.) The paint/hardware store shelf stock is what makes racing gasoline what it is today. Toluene is approximately 27% of the makeup of racing gas by volume whereas its only 9% of 92 pump gas! Toluene by itself has a RON+MON/2 of 118....pretty slow burning stuff..and a great octane booster.

As most don't know, fuel octane additives are useless to boost octane levels significantly. 8 oz bottles just won't move 15 gallons of pump gas very far, maybe a point at most. I don't think you need much past 98 - 100 octane (aluminum heads..add 5 points for iron and/or a short duration camshaft), if that, to correctly get the hammer down in your engine. If you think that you are going to go faster on higher octane save your money and buy a blower...simply not true, in fact can be the opposite.

You can mix your own racing gasoline by adding toluene to your tank at fill-ups. Let me say that this stuff is nasty and you should read all the precautions on the can. Don't get this stuff on you or the car. It's tuff on paint and tougher on you (carcinogen!!!). Start by adding 3 pints to 5 or 6 gallons of pump gas. See how it runs there. If it runs okay then start experimenting with backing off until it pings again or visa versa. Keep gallon(s) in your car. Actually you can get this stuff from a wholesale paint provider pretty cheap in gallons.

I have a friend who buys the stuff at 4.00/gal and adds a gallon and a half to his 11.5 to 1 big block every fill up (about 12 gallons). This equates to approx 21% toluene by volume (entire tank) and an estimated octane of over 102. The cost to do this with a $1.70 base for 92 comes up to average of less than $2 for the whole tank. Not bad!!......and really works.

Good luck in the laboratory!

ABOUT AVIATION FUELS - Aviation gasoline (or "av gas") is blended specifically for use in small aircraft. It's also commonly used by many high performance engine owners because of it's high stated octane rating (usually 100-110) and the relatively low price compared to racing fuel. Unfortunately this fuel is not all it appears to be. Av gas octane is rated on a different scale than gasolines intended for ground level use. What is 100 octane "av", is not necessarily 100 octane "ground level". Besides this, there is also a big chemical difference. Normal ground level race fuels are made up of gas molecules that have a "light end" and a "heavy end". The light end of the molecule ignites easily and burns quickly with a low temperature flame (as a piece of thin newspaper would burn). The heavy end of the molecule is not so easily ignited, but it burns with a much more intense heat (as an oak log would). This heavy end of the gasoline molecule is responsible for the hotter, more powerful part of the combustion process.

Small aircraft are constructed as very weight conscious vehicles. That's because their somewhat weak engines often have difficulty taking off with any extra weight. To help reduce this weight problem, av gasolines are blended with no heavy molecule end. This makes a gallon of av gas weigh substantially less than a gallon of ground level fuel. Since small plane engines turn very low rpms and produce so little power, the omission of the heavy end is not a horsepower issue. However, for high output pwc racing engines, there is defiantly a compromise in power. This, despite the fact that many pwc owners experience the desirable cooler operating temperatures that "av" gas offers. In addition, some blends of av gas will quickly separate from some oils used in premix situations. For the above reasons, we do not recommend the ongoing use of 100% av gas, and we will not prepare any "av gas" engine kits.

Despite all this bad news, running av gas (accepting the slight power loss) is usually a better choice than
burning down a high output engine on regular pump gas. In this situation, the best choice is usually a 50/50 mix of pump and av gas. That provides "some" heavy molecule ends for the engine.

Av. gas or race fuel?

A: The higher the octane rating, the slower and colder the fuel burns. If you run too much octane in your engine, it won't run very well because the burn is way too slow. If the octane is too high, the piston might already be at bottom dead center (BDC) and the fuel might still be burning! If the octane is too low, the fuel will burn too fast and too hot which causes detonation and leads to sure-fire engine damage! Aviation fuel is another no no. A famous engine builder (top fuel engines) told me a story about an engine that was in his shop that had major melt down in the cylinders. He said, "Arron, av. gas is for air planes! Where do you see airplanes? Up in the sky! Do you see cars up in the sky? No! How does your car run when you're up in the mountains? Yeah, like crap! There's no oxygen up there. Aviation fuel is designed to be run in a low oxygen atmosphere. What happens to that cutting torch flame when you add oxygen to it? Yeah, the flame gets hotter and turns blue! What do you think happens to an engine in a high oxygen atmosphere burning aviation fuel? Look right here at this engine and you'll know!"

He made a good point.

How to get your optimum tire pressure
Saturday, 10 February 2001 08:00

Tech: How to get your optimum tire pressure

Tire pressure is one of the most basic, yet affects you car or bike on the strip more than anything else. If you don't have the short times (60 ft.) that you think your car or bike is capable of, it's probably because you are spinning (or bogging) at the line. This can almost always be traced to improper tire pressure.

Here are some tips-

1. Buy yourself a QUALITY tire pressure guage! Don't settle for the cheap pencil guages you see in the auto parts stores or gas stations. These are very inaccurate and more importantly, inconsistent. You want a guage that will at LEAST read pressures the same way each time. Meaning, if you guage reads 25 psi when the actual pressure is 24.7psi and 28 psi when the actual pressure is 27.3 psi, you want a guage that will read those actual pressure the same way the next time you check your tires. If the actual pressure is 24.7, then your guage should read 25 (like it did before) not 26 or 24 (1 psi CAN make a BIG difference!).

Get a guage with a dial face and flexible hose. This eases the use of the guage immensely. Also, get one that "locks" the reading so you can view it without having to put pressure on the valve everytime.

Another consideration is your guage should have a bleed valve. This helps bleed excess pressure from your tires more easily. It's not required, but it does make life easier since you'll be doing this quite often.

If you run slicks, your guage should have a range no greater than 20 to 30 psi. Anything higher, you will have a tougher time getting accurate readings, since you most likely don't run more than 15 psi anyway. If you run street radial tires, then a guage with a maximum reading of 50 to 60 is about right. You will more likely be using pressures between 25 and 40 psi.

2. Now that you have a guage that is accurate and consistent, how do you know what tire pressure to set your tires to?

The generic test (slicks or radials)-
Do a rolling burnout (spin you tires while moving forward). Check to see the tires marks left on the pavement. See if the width of the marks are the same shade across the tread width. If the center is lighter than the sides, this indicates you have too little tire pressure. If the center is darker or the mark is narrower than the actual tire, this indicates too much pressure. Adjust until you have a uniform shade across the mark.

Now look at your tires. Check to see the wear pattern on the tire. Does it go across the entire width of the tread? Check to see if the edges show more wear than the center (underinflated) or vice versa (overinflated). You want a wear pattern that is equal across the entire tread width. Adjust as neccessary.

If it's your first time running slicks, make at least three runs using about 15 psi (or whatever pressure you ended up with using the generic tip). This should establish a good base line. Check your time slips and look at your 60 ft. times. Generally, short times for slick shod cars should be in the sub 2 second range. If your times are slower than this, adjust your tire pressure (up or down) until your short times improve.

Same as slicks except your tire pressure should be around 25 psi (or what you ended up with using the generic tip).

Note: To improve 60 ft. times further, you'll have to experiment with launch rpms and clutch release techniques. The above tips are mainly for tire pressures.

Honda Transmission Chart
Saturday, 03 February 2001 08:00
Honda Transmission Chart
The following transmissions will fit all the 1.6/1.8 B block motors.
Tranny code ? Y2 (aka Y21, S21) Y2 Y80 (aka Y20?) ? Y1 YS1? Y1 * (sometimes J1) S1
From these car(s): JDM Integra 98 spec.R USA EG2 (94-97 del Sol VTEC USA Integra Type-R
JDM Integra 96 spec.R

JDM Civic/CRX (EK/EG) w/B16A

USA 94+ Integar GS-R

JDM DC's w/B18C

USA 94+ Integra LS/RS w/B18B JDM Civic/CRX (EF) w/B16A USA 92-93 Integra GS-R JDM Integra (DA) with B16A USA 90-93 Integra LS/RS w/B18A
Operated by: Hydraulic Hydraulic Hydraulic Hydraulic Hydraulic Cable Cable Cable Cable
1st 3.230 3.307 3.230 3.230 3.230 3.166 3.307 3.250 3.166
2nd 2.105 2.105 2.105 1.900 1.900 2.052 2.105 2.052 1.857
3rd 1.458 1.458 1.458 1.360 1.269 1.416 1.458 1.416 1.259
4th 1.034 1.107 1.107 1.034 0.966 1.103 1.107 1.103 0.935
5th 0.787 0.848 0.848 0.787 0.714 0.870 0.880 0.906 0.742
Reverse 3.000 3.000 3.000 3.000 3.000 3.000 3.000 3.000 3.000
Final drive 4.785 4.400 4.400 4.400 4.266 4.266 4.400 4.400 4.400
Original tire size 215/45/R16 195/60R14 195/55R15 195/55R15 185/60R14 195/60R14 195/60R14 195/60R14 185/60R14
* Both JDM EF and DA's tranny are called Y1 but they have different ratios.
How to do a Burnout
Saturday, 03 February 2001 08:00

Tech: How to do a Burnout

Doing a burn-out is probably the second most important portion of a drag racer's ritual. The first being his/her reaction to the light.

Manual transmission:

1.    Engage your Line-Loc (I'm assuming you have one) FWD cars, just use the hand brake...

2.    Once your "locked" in place, select 1st (... if your engine is powerful enough, 2nd), then rev your engine to about 5000rpm (4cyl. Engines) and let out the clutch quickly.

3.    As soon as the tires start spinning, try to maintain your rpm (4-5K rpm). Do not rev up and down. The tires will heat -up more quickly when the wheel speed is kept UP.

4.    Wait 5 seconds (or more, depending on track condition or what works best for your set-up)

5.    When you're ready, release the Line-Loc, and let the car roll forward, while slowly letting off the throttle.

6.    Do a "Dry Hop" or practice launch. This part is optional. Some racers swear by it, while others claim that a dry hop just heats up the clutch and jeopardizes the actual launch.

Automatic trannies:

Same as the manual tranny, except for the clutch part.

Getting your tires to their optimum temperature is critical to a good launch off the start line. If you do not regularly do a burn-out and have traction problems, this may just do the trick. Few experiences rival the feeling of wrinkling slicks beneath you while the tires dig in for traction! Try it.

Project Car:"Clunky Junker"
Thursday, 01 February 2001 08:00

Project Car:"Clunky Junker"
1981 Toyota Starlet
Photos Taken by: Mr. Jude Crisostomo
Article by: Clunky Driver

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Since we have been working the past few months to bring you all the news and photos of the best looking, fast and quick cars from the top teams and drivers, DRP thought it was time for something different. And believe me, this is about as different as it gets!

With the plethora of fuel injection systems, high-tech electronic gadgetry, turbos, superchargers and more, DRP is proud (?) to announce its First Project Car... the "Clunky Junker".

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- 1981 Toyota Starlet 2 dr. (barely)
Engine- 2TG Twin cam, 8-valve, 1600cc
Induction- twin Solex 40mm carbs (running on 1 barrel each)
Transmission- T50 5-speed

Body- stripped (might have been stolen) interior, tubular front-end (cheaper than actually repairing the front), 6-point roll cage (great place to hang your laundry), TRD (like) body kit (made from left over tupperware), one peice (left) front end
Suspension- Lowered springs (mangled), 6-link rear (had extra parts)
Engine- headers (why is my sink leaking?), used Mallory coil with used ignition wires, custom oil leaks
Rear Differential- Posi weld, 4.something...

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This little beast is powered by the venerable 2TG, 1600cc engine from Toyota. In stock form, the equivalent of 110 horses is generated. In its current form, probably 50hp! Induction duties are managed (barely) by twin Solex side draft carburators (complete with spitting and sputtering).

Power (?) is then directed to the T50 5 speed transmission (grinding in every gear), till it all finally reaches the posi welded rear diff.

Weight up front was cut (literally) by the use of a tubular front clip and a one piece nose (or part of it anyway).

Present rolling gear is a set of 16" Wildcard wheels in the rear and a pair of 13" Tom's look-a-likes up front.

Why do we want to build this car? Well, DRP wants to show people out there that it doesn't take a ton of money to go fast and have fun.  We also want to make this car a platform to help teach the novice drag racer out there the basics of drag racing. We will cover every thing from suspension theory to engine tuning. Even some body work tech!

Our goal- to build a consistent 13 second bracket car, join races and teach people about setting up an affordable race car.

If you have a shop, please contribute your efforts to build up this car! We'll gladly post your shop on our "credits" page. Ms. Clunker (as we fondly call her) NEEDS your help. The dust collecting in our wallets is not enough to keep her going. Please donate your used parts so they can be used in this noble effort. All contributors will be named in the credits.

Be a part of DRP's
First Project Car!

Help save the "Clunky Junker"!

When we first purchased (yes, we actually bought this car!) the Clunker, it's flares were falling off, the front nose was just sitting on the front end, one wheel was facing the north star while the other was looking the other way. Towing it home was a like watching a truckin front of you, with its tail gate open, doing 160kph (just waiting for things to fall out).

After spending a few days bolting the flares back on, welding a mounting system for the nose, installing a new battery, flushing out the bad oil, brake fluid and gas, as well as spraying the whole car in primer black (the rainbow look is out), she was finally ready to start. (not to mention sweeping all the dried leaves and cob webs from every nook and cranny)

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Believe it or not, Ms. Clunker started without much drama. After fiddling with the carbs a bit, she even idles smoothly! Because of this, we treated her to some more black paint around the engine compartment (to hide the numerous blemishes).

All she needs now is an alignment. We tried to get it close enough, so we won't eat anymore rubber than we already have driving it around for testing.

Finally, the Clunky Junker is half way decent enough to snap some photos for this web page. With any luck, you can gaze upon her in living color (dying is more like it), this Saturday, Feb. 24th, at the Manila Harbour Centre. Keep your fingers crossed! Maybe she'll do an 18 sec. pass... let's just hope she makes it there first!

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