JRSC and octane at the track
 

(this is crossposted to the track/HPDE forum, so sorry about the redundancy)

I have a 2019 BRZ which has been the track a few times (JR oil cooler, camber bolts, brakes and tires...otherwise stock). While I love the way the car handles, I wish it had a few more horsepower; I think around 250 would probably be the sweet spot for me. I don't need to be the fastest, but there are a lot of fast cars in my group, and it would be good to keep up with the pack. I do mostly HPDE's and a few days of open track. No racing, but I usually drive in the advanced groups.

I am thinking of getting a Jackson Racing supercharger. The instructions "REQUIRE a minimum of 50% 100 octane fuel" at the track. 75 to 100% 100 octane is recommended.

Some of the tracks I would be going to may not have 100 octane. Also, while I recognize that going to the track is not cheap, when I can get it, it is over three times the price of 93 octane.

Can a JRSC run 93 a the track? I don't need crazy horsepower, and I would be happy to sacrifice some power for a 93 octane track tune, if one exists. Reliability is more important to me than power.

What is everybody doing?

Thanks.

Glenn

I am sure it’s a safety margin thing. Chances are it’s going to run just fine with 92. But JRSC wants to be on the safe side where car is WOT all the time and just maybe in certain situation that might be harmful for the engine. I do mix if not full 100 oct (too lazy to mix) as insurance against possible major engine damages. There were times I forgot and started day with 92s, that’s prob okey as I warm up to the track. After first session I’d fill up with 100oct to get roughly 50/50, and full 100oct from there on. It drinks gas faster than my 8cyl NA car lol!

Do you have E85 available? That would be the safest track fuel. Other option would be a custom tune not the canned JRC. Hit up CSG they will keep you safe.

E85 is the way to go at the track for sure. And way cheaper. You can even bring it with you. Car can easily fit 4-6 jerry cans in it.

Do you mean E85 can be used with JR factory tune?

It cannot

The higher octane is safety margin. If you choose to roll the dice, you can do so, and many do successfully, but in the case of an engine failure due to knock/detonation, know that higher octane could have prevented that.

Race fuel, Race pads, Race maintence, makes sense, for a car being driven at a Race track.

So just to be sure....
There is no safe way to tune a BRZ for the track with a JRSC on 93 without risking serious engine failure. I'm okay with being slow... just looking for ways to buy some HP without undue risk.

Thanks for your contributions, everybody.

There's no safe way to track any car without any risk.

The question here is, what risk is acceptable to you?

Track driving will heat soak your intercooler far more than street driving, which means higher intake temps, which means higher risk of knock/predet. Higher octane fuel means higher knock resistance.

It has nothing to do with the tune, and everything to do with the driving conditions.

Thanks for your feedback, everybody. As far as E85 goes, some tracks may have some without traveling too far. Or I could take a bunch to the track. Wouldn't be convenient, but doable. Two questions:

1. Would E85 provide the octane/ antiknock protection to make a JRSC (relatively) safe at the track?
2. Given that I would be lugging a bunch of E85 to the track, could I dilute it with pump gas to E60 or something like that? I would have to measure ethanol content and/or install a flex fuel kit.

Thanks in advance.

If all you need is E85 in your car then you could fit around 50-60 gallons. In just the trunk, six 5-gallon jugs will fit perfectly. Lay down the rear seat and you can fit at least three more, and there is the passenger seat/floor.

Yes, E85 will greatly reduce the risk, even if you used it to add power, but with it the car would be heavily detuned if power was tuned to be the same.

Yes, do flex fuel and yes you could do a mix. The effective knock resistance drops as the ethanol % drops. The tuner and be conservative across the board if you wanted.

Why not stay NA and get Flex Fuel and try e85 at the track with a proper tune. See if thats enough power. Staying NA depending on number of Laps you could only need 3-4 5 gallon buckets vs boosted you will need alot more.

E85 can be a pain in the ass if it's not readily available. Too much work IMHO unless you have it everywhere (we don't in CT). And it will help with detonation but not with engine temps. Put your money toward a custom tune with a good tuner and they should be able to tailor it to whatever you need on safety margin with 93, especially if you're not looking for outright power. You can even switch between tunes and can have a lower power 'safety tune' and a higher power 'street tune'. Then take the rest of the money and put it into heat management - you already have a good start with that oil cooler. Vented hood, upgraded radiator, etc. It also depends on experience and how hard you're going at the track - someone like CSG Mike will really push things harder than your typical track afficionado, and your track afficionado will push the car harder than folks who go to the track a couple times a year.

Just saying, but I can't WOT any more than anyone else can in a given car!