In my search for the best possible everything for the race car, I came upon some tuning questions. Looks like my motor will run best (most hp/tq) with 102 octane racing gas, allowing for maximum ignition timing.
What do ya'll use? and if you use race gas, where do you get it (if you're in the NoVA area)

TIA.

 

most power on our engines was also made with octane from 98-102....actually topped out at those octanes.....we started with 110 then mixxed down to 100 ish.....
have a local gas station that sells 110 for 4.50 a gallon.....so we end up spending about 3.25 by the time we mix it up

 

hi.

i use 100 LL avgas in my h1 car. i buy it for cash at the local, tiny airport nearby.... shhhhhhh......

my h1 car has higher compression, and advanced timing. it seems to run well on 93, but i use the 100 octane as a safety factor. less chance of detonating while racing, especially last year, when i had the smaller radiator and was always overheating at the end of the race.... oh, and you will NOT be able to hear any kind of detonation when racing. you can barely hear anything!

on my backup racecar, a 93 Ford Probe GT (stock motor) i use 93. no point in using anything more....

good luck.

 

The suggestion has been made to me on multiple occasions that now that I'm at 19 degrees of timing, I should run 100. I'm going to start next season.

 

Whatever you decide to use, if you are racing SCCA, make sure it will pass the fuel tests required by the GCR. The varying classes (IT, Prod) have differing fuel requirements. However, I don't recall the details.

 

When I need race gas I mix a 4:1 ratio of 100 octaine pump and toluine. I'm not sure if it makes my car run better (no worse) but it makes me think the car's faster

 

<digging in the GCR CD that is permanently loaded in the laptop> the GCR only talks about the dielectric constant (DC) and reaction to test chemical. I have no clue how that related to octane...

Geratol: toluene is basically octane booster (toluene is 114 octane) - so you are basically running 102.8 octane gas ((4 gal * 100) + (1 gal * 114)) / 5 gal.

 

only use it for street racing....................................

 

I have always run 93 octane in my IT cars but never did any testing or tuning with higher number stuff. As noted, SCCA is in recent years very specific about fuel testing and what is allowed. It was caused quite a hubub as testing methods and samplers can be finicky. The problem arose when at the Runoffs and some National events, some guys were running a witch's brew of really nasty and unhealthy fuels and additives. Standing on the grid when cars rolled away, they said sometimes the stuff made your eyes water and wonder what kind of health hazards were around.

Their response was a testing system with lots of bugs (many normal street pump fuels wouldn't pass because of everyday additives). I have not raced since this has gone in force so I can't speak from personal experience on actually being involved.

Since dynos are more popular now so real numbers and tuning can be had in ways that it wasn't just 5+ years ago, I'd be very interested in seeing what effect it has on non-high compression engines.

 

Sebastian, CM is talking about passing fuel tests in general. So whereas you may find a good gas price at the Wibleymart in NoVA, there's no guarantee that gas will pass a fuel test. The fuels (now that I know to look for this) at the track have the test numbers on them so you should feel rest assured that if these numbers are ok, you are good to go with that fuel be it 93, 100, 110, whatever.

 

For max power we also run 100 octane and 21 deg timing and run it very lean. At the edge of detonation for MAX power. may run very HOT but will not detonate. Good luck. we gained 4 hp and some torgue by running it leaner.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SJR &raquo;</TD></TR><TR><TD CLASS="quote">&lt;digging in the GCR CD that is permanently loaded in the laptop&gt; the GCR only talks about the dielectric constant (DC) and reaction to test chemical. I have no clue how that related to octane... </TD></TR></TABLE>

It's not related AFAIK. But, the GCR (or maybe ITCS) also states the fuel may be tested for additives (I do not recall if it specifies which additives). My point is simply to be sure whichever fuel you choose meets these requirements. AFAIK, all the Sunuco unleaded fuels will pass the SCCA tests. I do not know about AVGAS or other non-automotive fuelds that people occasionally use.

 

CM, Adam: thanks, gotcha. I had misunderstood the comment.

ITAIntegraLS: my builder runs quite a bit of timing, from an ECU programming point of view (above 30deg) - I guess different engines (mine's a D16A6) run different amounts.

Morgan: come on down to Haymarket for a street racing extravaganza. We can try to dodge the Po-lice chief's rounds from his fully auto assault rifle (gotta love the country, really!)

Lee: apparently, running even non-high comp engines on high octane gas allows you to run more timing, up to a point, and yields a little HP...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SJR &raquo;</TD></TR><TR><TD CLASS="quote">

Geratol: toluene is basically octane booster (toluene is 114 octane) - so you are basically running 102.8 octane gas ((4 gal * 100) + (1 gal * 114)) / 5 gal.

</TD></TR></TABLE>

Yeah, I have done the calculations but the reason for toluene is that I heard it's supposed to release more joules per mole (it's been so long since I took a chemistry class so I'm not sure if I have the terms right) and it is supposed to brake down the same as gasoline.

But as I said before, if it makes me think I'm faster, then that's the biggest advantage for me.

 

Well, when we got the ECU all screwed up in my car for the ARRC we HAD to run 100 octane. We started the first qualifying session on 93 and the car just plain died at 6400 rpms (a whopping 102mph top speed). It was missing and sputtering and just plain coughing and wheezing.
So, we took the only option we had left... We took the air filter off and loaded up with 100 octane. The results were impressive. The car still didn't run all that great but we got up to 108, 109 on the back straight and eliminated most of the missing and wheezing. It would now run all the way to the rev limiter.

After we get the ECU sorted out I plan to do some dyno testing with 100 octane. Based on what we saw at the ARRC I think we can make some real gains with the motor running right.
I just wish I could find a cheaper place to pick it up. Its $6.00/gallon trackside at R/A.

 

Oh, and I love the smell of race fuel in the morning.

 

race gas, to use or not to use?

unless your over 13:1 compression.......it's a waste of $$$

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B18CXr &raquo;</TD></TR><TR><TD CLASS="quote">unless your over 13:1 compression.......it's a waste of $$$</TD></TR></TABLE>

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ITAIntegraLS &raquo;</TD></TR><TR><TD CLASS="quote"> we gained 4 hp and some torgue by running it leaner.</TD></TR></TABLE>

???

 

Toluene is a NO NO for SCCA so far as I know. It is an additive that is not found in pump fuel.
You can run any PUMP gas you want as long as it meets the fuel test. As I read the GCR the DC is 15 for race/pump fuel. Sunoco's website has some excellent info on the subject. You are all aware that the "official" fuel of SCCA and NASCAR for 2004 is Sunoco and whatever they offer at the track will pass. You cannot use anything other than pump Unleaded unless the car calls for Leaded (Detroit iron would be thcase here). I seriously doubt that AV gas would be a problem-but then again it is not engineered for cars- remember that it must meet the Fuel test.
Our CRX is box stock under the hood and runs great on Sunoco 93 and Union 76 100 Octane (that's what we could buy at Watkins Glen this year). The timing is within spec-and yes the car does perform a bit better overall. Sunoco GT100 is a pump grade fuel according to the literature-so it should be legal.
For those running NASA events-the situation is very similar.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SJR &raquo;</TD></TR><TR><TD CLASS="quote">In my search for the best possible everything for the race car, I came upon some tuning questions. Looks like my motor will run best (most hp/tq) with 102 octane racing gas, allowing for maximum ignition timing.
What do ya'll use? and if you use race gas, where do you get it (if you're in the NoVA area)

TIA.</TD></TR></TABLE>

You can get VP racing fuel at C&C in Manassas (on route 28). They carry a 100 and 103 octane unleaded fuel.

-Pete

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by urbanlegend21 &raquo;</TD></TR><TR><TD CLASS="quote">only use it for street racing....................................</TD></TR></TABLE>


mang i'm not the only one!!

 

remember, the higher the octane the harder it is for the full to burn. If you go too high for your setup you will actually end up loosing power

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by rjr162 &raquo;</TD></TR><TR><TD CLASS="quote">If you go too high for your setup you will actually end up loosing power</TD></TR></TABLE>

Dyno is your friend.

 

Yes thats why you run as little fuel as possible very lean so you will make power not lose power while keeping detonation away.

 

How many people run a knock sensor on there race cars, I run race gas for peace of mind because I have no knock sensor. I usually mix 50/50 110 and 94 with a little 94 aready in the tank. It may cost me a little extra but I've blown a motor before due to detonation and don't want to do it again.