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-   -   GT radial SX2 track owners question about PSI (https://www.ft86club.com/forums/showthread.php?t=143953)

jflogerzi 01-21-2021 11:04 PM

GT radial SX2 track owners question about PSI
 
What PSI do you run hot on track? Trying to figure out what is the best/optimal PSI...

I run 245s on a 17x8 wheel

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CSG Mike 01-22-2021 01:27 AM

Depends on your setup and preference. There is no universal one best, just how your tune is customized to your setup.

Use a pyrometer. You're welcome to borrow mine as long as you don't damage it.

jflogerzi 01-22-2021 09:03 AM

Yup I get that.

Setup mostly in sig. Suspension is stock 17 non pp dampers, rce yellows, and peddlers top hats. I have a whiteline 20mm sway bar up front on stiff and a 2017+ oem rear sway out back. Alignment is -2.3 up front and -2.2 in the back

I normally shoot for 30-32psi hot. I feel like the higher it goes the less grip the car has...

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Pat 01-22-2021 12:17 PM

I like 34 hot with 225 45 17 SX2s on an 8" wheel. 3.6* front camber, 2.5* in the rear.

CSG Mike 01-22-2021 08:19 PM

most of the socal records are held by 37-40psi hot

jflogerzi 01-22-2021 08:21 PM

Really wow... So excuses my ignorance what's the benefit of having a higher PSI vs lower PSI

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Pat 01-22-2021 09:35 PM

Quote:

Originally Posted by CSG Mike (Post 3401624)
most of the socal records are held by 37-40psi hot

Hmm.. very interesting. I wonder what the rest of their setup is like.

Pat 01-22-2021 09:50 PM

Quote:

Originally Posted by CSG Mike (Post 3401624)
most of the socal records are held by 37-40psi hot

So maybe they go out and turn a fast lap with cold tires at 34 and by the time they are done they are up to 40 hot? Or do you really think the fastest laps are turned with tires between 37 and 40?

CSG Mike 01-22-2021 10:53 PM

Quote:

Originally Posted by Pat (Post 3401657)
Hmm.. very interesting. I wonder what the rest of their setup is like.

Stock class car in many instances, so.... quite literally a stock car, with a 17 rear sway, and camber modification, brake pads, and oil cooler.

In the case of William's car, -4ish front camber, -2.7ish rear camber, 0 toe front/rear.

His fastest laps are typically laps 6-10.

CSG Mike 01-22-2021 10:54 PM

Quote:

Originally Posted by jflogerzi (Post 3401625)
Really wow... So excuses my ignorance what's the benefit of having a higher PSI vs lower PSI

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There isn't. That's where it happened to end up when tuned by pyro.

SCFD 01-23-2021 08:34 AM

Quote:

Originally Posted by CSG Mike (Post 3401679)
Stock class car in many instances, so.... quite literally a stock car, with a 17 rear sway, and camber modification, brake pads, and oil cooler.

In the case of William's car, -4ish front camber, -2.7ish rear camber, 0 toe front/rear.

His fastest laps are typically laps 6-10.


Why a rear sway bar instead of front?

jflogerzi 01-23-2021 10:42 AM

Quote:

Originally Posted by CSG Mike (Post 3401681)
There isn't. That's where it happened to end up when tuned by pyro.

I need to read up on these pyro tire devices.

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CSG Mike 01-23-2021 06:30 PM

Quote:

Originally Posted by SCFD (Post 3401727)
Why a rear sway bar instead of front?

Rotation.

We don't really slalom on tracks the way you do in AutoX, so there's not a reason for giant front sway.

Pat 01-23-2021 08:59 PM

Abe and I were talking about these hot tire pressures that set lap records in SoCal. We still struggle to understand how this is possible given our data. I could understand one or two PSI difference but six is really difficult to comprehend. Especially when I can feel 35 is too hot relative to 34. I have a lot to learn.


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