e85 or wider wheels? - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

colobrio · 01-20-2021, 10:01 PM

Odd question, I realize. I plan on doing some 86 Cup events this year. Under the points-based classing they use, to be street-class eligible with existing mods, I can either run e85 and 8" wheels (8.5 technically, but no one seems to make 17x8.5 for our cars that will clear BBKs), or forego the e85 and get to use 9" wheels. I'll be on SX2s either way, 235s if 8" and 245s if 9". It's not like I'm going to buy two set of wheels and test them, so - any thoughts on which combo would be quicker? I've got an ecutek tune with an e85 map (along with a 91 octane) and basically a full STX build, otherwise. Cheers.

Purist · 01-21-2021, 01:00 AM

It will depend on the track and other factors, but having built my car up from stock one mod at a time, and racing with each mod to evaluate its effect, I would suggest that E85 will reduce lap times much more than 10mm more tread on each wheel.

My racing was up twisty hillclimbs with very few straights and mostly up steep hills.

Sent from my SM-G973F using Tapatalk

colobrio · 01-21-2021, 09:25 AM

Quote:

Originally Posted by Purist

It will depend on the track and other factors, but having built my car up from stock one mod at a time, and racing with each mod to evaluate its effect, I would suggest that E85 will reduce lap times much more than 10mm more tread on each wheel.

My racing was up twisty hillclimbs with very few straights and mostly up steep hills.

Sent from my SM-G973F using Tapatalk

Thanks, Purist. Having bought the car q year ago essentially as is and used it primarily for autocross (no e85 allowed), that's exactly the kind of insight I was hoping for. Tracks will be High Plains and Pueblo; plenty of curves, but more straight than it sounds like you usually encounter.

Purist · 01-21-2021, 05:00 PM

More straights are even more reason for E85. The increase in torque will see you significantly quicker IMO. Is be keen to hear other's insights.

Sent from my SM-G973F using Tapatalk

CSG Mike · 01-21-2021, 05:02 PM

You can always run the 245 on a 8" if you like, and run E85.

Pat · 01-21-2021, 05:20 PM

Hey Colobrio, I'm looking forward to you hopefully joining us. The organization typically has loaner wheels and tires if you want to try some out. We currently have a set of 8" wheels with 225 SX2s on them. I'm hoping to have some 9" wheels with 245 SX2s soon, also. If you'd like to demo either one send me a private message.

Yzu · 01-21-2021, 05:28 PM

E85 def helps on T7, T11 at HPR. For me at least.

colobrio · 01-21-2021, 05:47 PM

Quote:

Originally Posted by CSG Mike

You can always run the 245 on a 8" if you like, and run E85.

Do you think 245s would be quicker on 8s than 235s? I was assuming they would be pinched enough to start getting counterproductive.

colobrio · 01-21-2021, 05:50 PM

Quote:

Originally Posted by Pat

Hey Colobrio, I'm looking forward to you hopefully joining us. The organization typically has loaner wheels and tires if you want to try some out. We currently have a set of 8" wheels with 225 SX2s on them. I'm hoping to have some 9" wheels with 245 SX2s soon, also. If you'd like to demo either one send me a private message.

Thanks, Pat. Last time as was at High Plains (in November), I chatted with someone about 86 Cup while filling up at the pump. Was that you? I was in a (WR) blue BRZ.

Pat · 01-21-2021, 05:51 PM

If I were going to run 8 inch wheels my personal preference would be 225 tires. That's what I have run for the last 5 years.

Pat · 01-21-2021, 05:53 PM

Quote:

Originally Posted by colobrio

Thanks, Pat. Last time as was at High Plains (in November), I chatted with someone about 86 Cup while filling up at the pump. Was that you? I was in a (WR) blue BRZ.

Hmmmm... I don't think so. My car is white, and I am 6'3".

colobrio · 01-21-2021, 06:00 PM

Quote:

Originally Posted by Yzu

E85 def helps on T7, T11 at HPR. For me at least.

Thanks for the input. 11 I can totally see, digging out of the almost 180 up that grade. On 7 I hit 80mph at half throttle - just how fast are you able to take it? Or did you mean 6? Either way, I am looking forward to trying e85 on track. I've got a tank of it in for the first time now, and just getting on the freeway it feels a little stronger.

colobrio · 01-21-2021, 06:02 PM

Quote:

Originally Posted by Pat

Hmmmm... I don't think so. My car is white, and I am 6'3".

So, like me your helmet constantly is pressing gently into the liner up top?

CSG Mike · 01-21-2021, 06:04 PM

Quote:

Originally Posted by colobrio

Do you think 245s would be quicker on 8s than 235s? I was assuming they would be pinched enough to start getting counterproductive.

In most scenarios, yes.

245 on 8" + E85 will almost universally be faster than 245 on 9" + gasline.

01-20-2021, 10:01 PM	#1
colobrio Member Join Date: Dec 2019 Drives: 2013 BRZ, 6MT, WR Blue Location: Colorado Posts: 39 Thanks: 14 Thanked 5 Times in 4 Posts Mentioned: 1 Post(s) Tagged: 0 Thread(s)	e85 or wider wheels? Odd question, I realize. I plan on doing some 86 Cup events this year. Under the points-based classing they use, to be street-class eligible with existing mods, I can either run e85 and 8" wheels (8.5 technically, but no one seems to make 17x8.5 for our cars that will clear BBKs), or forego the e85 and get to use 9" wheels. I'll be on SX2s either way, 235s if 8" and 245s if 9". It's not like I'm going to buy two set of wheels and test them, so - any thoughts on which combo would be quicker? I've got an ecutek tune with an e85 map (along with a 91 octane) and basically a full STX build, otherwise. Cheers.

01-21-2021, 01:00 AM	#2
Purist Senior Member Join Date: May 2017 Drives: Subaru BRZ Location: Australia Posts: 349 Thanks: 125 Thanked 261 Times in 145 Posts Mentioned: 5 Post(s) Tagged: 0 Thread(s)	It will depend on the track and other factors, but having built my car up from stock one mod at a time, and racing with each mod to evaluate its effect, I would suggest that E85 will reduce lap times much more than 10mm more tread on each wheel. My racing was up twisty hillclimbs with very few straights and mostly up steep hills. Sent from my SM-G973F using Tapatalk __________________ Less More

01-21-2021, 05:00 PM	#4
Purist Senior Member Join Date: May 2017 Drives: Subaru BRZ Location: Australia Posts: 349 Thanks: 125 Thanked 261 Times in 145 Posts Mentioned: 5 Post(s) Tagged: 0 Thread(s)	More straights are even more reason for E85. The increase in torque will see you significantly quicker IMO. Is be keen to hear other's insights. Sent from my SM-G973F using Tapatalk __________________ Less More

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