Premium vs Regular gas for track day

[GTP]

Look, guys, to add clarity to my post. This is NOT about cost. It is about risk.

If there was no risk to the engine and high test only adds HP then I would put in regular gas.

If there is risk to the engine (and there seems to be consensus here) then of course I will put in high test gas!

Sponsored

 

[SL8888]

Without hesitation, tires, brakes, oil, gasoline for cars. Get the best that you can AFFORD !
If you’re only able to afford cheap tires or brakes or gas then that’s all you can afford and you do your best.
If you can afford better tires, brakes, oil & gas, but you go on the cheap.
Then what ever happens because of your thriftiness is on you.
That goes for any vehicle that you drive in my opinion.
Wife or daughters car has to be the best you can afford also.

 

[Aless_andro00]

I'm sure there will be some strong opinions on this, but ... Is there any good reason not to run regular gas for track day?

That's what I have been running most of the time. I don't care about a little extra HP, and fuel cost for an out-of-town track weekend really adds up. I just don't know if there is any reliability risk to the engine with regular 87 octane gas.

If your car needs premium gas, which is usually 91 octane or higher, putting in regular gas (87 octane) during a track day can cause knocking. This is especially true if you have a high-performance engine and you're really pushing your car on the track. It's best to stick with the recommended fuel to avoid issues.

 

[sachmo133]

The cost difference is so small it doesn’t make sense. A track weekend is about $1000 for event and insurance for me. So the extra $50 for 93 vs 89 is not a problem. I also only use Top Tier gas. And I would be running 93 at least for a full tank before the track day.

 

[davanz]

Some people have this opinion. They point out that today’s engines are equipped with knock sensors to adjust timing, and therefore allow use of lower octane fuel. And that is true. But I go by the following logic. If the knock detectors detect knock, and the engine controller adjusts timing, the knocking or pre ignition has already occurred to some degree. Past tense. And thru how many combustion cycles in your hot engine, at high RPM, who knows. Over the life of the engine I don’t want that for my car, it’s just extra stress and wear that can be avoided. Using a higher octane fuel may not totally eliminate knock, but it lessens the likelihood.

 

[Johnny maverick]

Premium cars. Premium fuel.

 

[mavisky]

The entire point of the extra octane is pre-detonation prevention, or knock prevention. Knock is most easily encountered when running poor fuel under heavy throttle load.

The idea of inviting additional pre-detonation by saving a few dollars per tank when you're already spending hundreds in entry fees, brakes, tires, fluids, etc... is just insanity to me. You live in Indy, there should be 93 available around. If not buy some 91 and add some octane booster in just to be extra safe.

A new long block is $3,000 so a few bucks per tank in gas to avoid that is real cheap insurance.

 

[Bob Lob Law]

Some of you clearly need to read his responses.....

 

[mavisky]

Look, guys, to add clarity to my post. This is NOT about cost. It is about risk.

If there was no risk to the engine and high test only adds HP then I would put in regular gas.

If there is risk to the engine (and there seems to be consensus here) then of course I will put in high test gas!

In what way would there not be risk? It seems like you have a fundamental misunderstanding about how modern engine control systems work and how octane affects how those systems work.

 

[Bob Lob Law]

In what way would there not be risk? It seems like you have a fundamental misunderstanding about how modern engine control systems work and how octane affects how those systems work.

Your reading comprehension is the fundamental misunderstanding.

 

[mavisky]

Your reading comprehension is the fundamental misunderstanding.

Thank you for your massive contribution to this thread. OP has repeatedly stated "if there is a risk". There is 110% a risk. If he's even questioning if there is a risk he has a fundamental misunderstanding.

 

[GTP]

Thank you for your massive contribution to this thread. OP has repeatedly stated "if there is a risk". There is 110% a risk. If he's even questioning if there is a risk he has a fundamental misunderstanding.

Uh, yeah, hence why I asked the question. Forgive me for my ignorance, and thanks to all for their knowledge and experience.

 

[Andy13186]

Definitely the best octane you can get, no question about it...

 

[Jstang23]

Our engines do have knock detection and the ability to adjust the timing according to which octane fuel we choose to run. This does NOT mean that running 87 is perfectly acceptable for high stress environments.

Your car does have a limit to how much timing it can pull. If you're tracking around 220 CHT and full throttle your engine won't be able to prevent pre-detonation should it occur.

Running a higher octane fuel reduces the fuels ability to pre-detonate, meaning the car has to adjust less to prevent the environment in the combustion chamber for pre-detonation.

Yes you can run 87 on the track and technically you would more than likely be fine. But in the event you create the conditions suitable for pre-detonation then you’ll wish you had a higher octane. My local track doesn’t even have 87 available inside.

Sponsored