STU guys check in. Set ups

[tsrapophis]

Originally Posted by AustinTX

3.5 degrees isn't exactly camber challenged, but a Subaru will require a good setup to not chew through the front tires regardless. RE71's are fast but will heat cycle out before they run out of tread. BFG's will be just as fast or faster for the same size with a good setup and will get harder to drive as they wear down past 2/32, but they will still be fast until nearly bald. No experience with Yokohama since my order from June never arrived prior to solo nationals in September. #notevenbitter

Thanks for the info! I'd happily just get rivals but we usually have a couple cold weekends at the beginning and end of the season. Other guys in my club who have been running them have had trouble keeping them warm in those cases. And I can confirm, my RE71'S heat cycled out with 40% tread left.

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[AustinTX]

Subarus don't have as much trouble heating street tires as other cars do. Fronts will warm up within a run. How wide are your current wheels and tires?

[tsrapophis]

I'm running 255/40R17's. It might be that I'm over concerned about heat because my re's turned into bricks at the end.

[speedyHAM]

Originally Posted by tsrapophis

I'm running 255/40R17's. It might be that I'm over concerned about heat because my re's turned into bricks at the end.

All tires will turn into bricks eventually unless you wear the tread off fast enough. It happens because of the heat cycling. For instance, after about 75 runs the old Hoosier A6's were at least 2 seconds slower than a new set.

[dhatcher]

Spring rate question:
I'm building up my 2020 sti for STU competition (not a complete build but, that's the class I'm going to end up in). I'm budgeting about $1,500 for coilovers (so no Ohlins). I'm pretty close to pulling the trigger on some Feal 441+ with Swift springs and Mike over there has told me the 441+ has some wiggle from from the stock 8k spring rates. They can go up to 10k.

Question is; should I run 10k on all 4 corners or run 9k up front and 10k rear?

[AustinTX]

Originally Posted by dhatcher

Spring rate question:
I'm building up my 2020 sti for STU competition (not a complete build but, that's the class I'm going to end up in). I'm budgeting about $1,500 for coilovers (so no Ohlins). I'm pretty close to pulling the trigger on some Feal 441+ with Swift springs and Mike over there has told me the 441+ has some wiggle from from the stock 8k spring rates. They can go up to 10k.

Question is; should I run 10k on all 4 corners or run 9k up front and 10k rear?

Maybe wait til you can afford better shocks then. I'd start with at least 11k up front and probably 12-14k in the rear. Especially if going straight to 265's. But seriously, I wouldn't mod the heck out of a new car if I had to be too careful on the budget. As soon as you modify anything under the hood or in the ECU, Subaru will not be there to help you 'when' something goes wrong

[dhatcher]

Originally Posted by AustinTX

Maybe wait til you can afford better shocks then. I'd start with at least 11k up front and probably 12-14k in the rear. Especially if going straight to 265's. But seriously, I wouldn't mod the heck out of a new car if I had to be too careful on the budget. As soon as you modify anything under the hood or in the ECU, Subaru will not be there to help you 'when' something goes wrong

Yeh I'm accounting for that already (part of why I'm not going balls out). Keeping some money reserved for "what if" but, I still want the fun of coilovers (as much as I can afford).

Currently the build is:
AEM CAI
Borla S Type cat back
Cobb AP
Racecomp Eng. front & rear sway bar + kartboy endlinks
Konig Ampliform 19x9.5 +35 Wheels
265/35/19 Goodyear Eagle F1 Supercar 3 tires

Am taking a chance on those tires since they're not the RE71R's (ran those plenty last couple of seasons on my last car) but, I wanted to do at least a couple of track events this year in addition to the car being a daily driver. So I'm hoping to get a bit more life out of them than the Bridgestones. Yes I know "get a spare set of wheels!" ...I'm lazy. :P

[AustinTX]

Is the AEM part of a custom tune on the AP? Or does the OTS tune cover the use of the AEM? If not, might wanna start with getting a proper tune.

STU allows 11" wheels - at least go to 10's. Especially with 265's. The SC3's should be okay, but clearly not the best tire at the moment. Yokohama AO52's have that spot right now.

RCE bars are probably fine depending on how the car handles after the coilovers. Not sure about kartboy endlinks - if they are poly/rubber bushing based, don't bother. The stock end links are better in pretty much every way.

All of my advice is based on a full build. Asking about things that aren't part of a full build isn't gonna get your preferred response :P

[dhatcher]

Just got the car and have ordered the stuff so nothing is on it yet (eagerly awaiting the UPS truck).
I was planning to use an OTS map from Cobb (emailed them to get their thoughts on exactly which map to use) but, may go for a professional tune if they can't recommend a good setup otherwise.
Eh, 9.5 is good enough. Should get the full use of the 265 out of that.
Interesting to hear your thoughts on the Kartboy endlinks, they were about the only brand I didn't try on my last car. Thought they were kind of the defacto choice these days. I tried a bunch of the others and disliked them all. Might just return them then if you say the stock links are better, I'm inclined to believe you and save the money

Yeh the SC3's are sort of a compromise of a tire for me. daily driver / weekend warrior, something that has a tiny bit more life than the RE71Rs will suffice at the expense of a little grip.

[jesup16]

Offering up some different and similar opinions:

Your tire choice is going to inhibit your ultimate performance:
* Why 19" wheels? Are you concerned about clearing the Brembo's? You can go to 18's, save weight and money.
*You can run almost any tire in a 265/35/18: A052's, RE71R's, etc.
* 9.5 won't maximize a 265 wide tire. FWIW, the C5 guys are mounting 265s A052's on 18x10.5 wheels and they are every bit as wide as 285/30 RE71R's on the same wheels. 265 A052's won at nationals on a heavy E92M3...
* Why are you concerned about life if you have the stock wheels to DD on and a set of autocross/track tires? Some tires heat cycle out before they wear out...

I personally like the kartboy endlinks... and you may want something adjustable if you are going to alter ride height, as you need to adjust the preload on the bar. Some people do go with solid, non-adjustable endlinks and have the suspension configured for that. If the car has to be live-able, I'd stay with the kartboy links.

What size bars? I don't know much about the preferred setup for your chassis, but bar size and construction (solid vs hollow) paired spring rates will paint a more clear picture for us.

[dhatcher]

19" wheels because the gearing is shorter in the STI than the WRX I had and I want to be able to hold that 2nd gear out a little bit longer.

I mean to say anything wider than 9.5" isn't really necessary for me and has potential to add weight to the wheel. The measured width for 265 tires is 9.5" so I'll be getting the full section width of 265. Not like when I ran 255's on 8 inch wide rims on my WRX.

Yep, I am aware that my tire choice is not the best choice for strictly autocross but, for the combo of daily driving, autocrossing and a couple of track events I think it should be decent all around. For what it's worth, where I autocross (Crow's Landing), it gets pretty damn hot in the summer (easily 100+) and I often co-drive with friends so my tires usually get a little warmer. eh *shrug*

As for why not swap on the stocks when I'm done with events; I'm getting older and lazier and I also happen to enjoy the way the car looks with the race wheels and tires. eh *shrug*
(I can always go back to RE71Rs if the Supercars get annoying. Just have to wear them out first ).

I actually made a last minute change based on several folks advice including AustinTX's advice about the stock links. I decided to ditch the RCE bars and Kartboy links, stay with the stock ones and put the money towards better coilovers (whatever those may be, currently looking at the BC Racing HM Series).

I've also recently learned that apparently the EJ25's have a pretty serious oil starvation issue and I may have to throw $1000 at oil mods if I want to keep the engine alive for long.

[milab21]

If and when you go sway bar and endlinks, check out super pro 24mm rear bar, endlinks, front D bushings for the OEM front bar, and the super pro roll center kit. Along with coil overs, you will want to get adjustable rear control arms. Like said, save for a decent set of shocks. Ohlins, AST, MCS..

I would ditch the aem intake as well. Go for a catted down pipe and a pro tune. Then fuel pump, injectors and equal length headers if you want more.

Next time I recommend a set of 18" wheels over the 19"

[littledrummerboy]

fwiw, I'm running 275 on 18x9.5" and 275's measured rim width is also 9.5". Its slightly less responsive than the 265 i was previously on, but I'm not fully convinced the (slightly) extra contact patch is making up for it yet. That said, i'm on +45 offset which gives me fender room without rolling, and room for camber.

Personally, I like a matched F/R spring rate and using a fatter adjustable rear bar to compensate if it still feels too understeery. A matched rate should get it to be at least more neutral with the rear carrying less weight than the front. An adjustable rear bar can then be added to fine tune it.

Its personal preference, but to me, its easier to add rear bar and adjust it on a matched rate to mitigate understeer, than trying to dial back if the car is too twitchy on rear springs that are stiffer than front.

[jesup16]

Are roll-center kits ST legal? I didn't think they were...

No amount of wheel/tire size manipulation is going to help the STI gearing in 2nd... if its a pro-level course, which you are likely to get at Crow's, you're gonna be in 3rd at some point or riding the limiter. No way around it.

I hear Crow's is a good surface for grip... prob tough on tires. A052's prob won't last long. I've also heard good things about the SuperCar's, especially for track duty and high temps... so try them and give us some feedback. I just think once you get car sorted and start competing, you're gonna want to be a top-level tire: A052, RE71R, RivalS. Also, the Nexen SUR4G seem to be a good option and aren't far off those 3 top options... plus they are a bit cheaper IIRC.

265 on a 9.5 isn't really pinching the tire... if that's what you're comfortable with, great! we're all just saying you can get more out of them. FWIW, a lot of the GD guys put the 255/40/17 on a 17x10 on the front and it seems to work well. I got out of my STI before they changed the rule from 245's > 265's... I ran the 245's on 9.5 wheels.

Here's a pic of 265/35/18 A052 vs 285/30/18 RE71R (which I run) mounted on the same 18x10.5 wheels.
https://photos.app.goo.gl/kiJCeDeztQsbBuT57

[jesup16]

Originally Posted by littledrummerboy

Its personal preference, but to me, its easier to add rear bar and adjust it on a matched rate to mitigate understeer, than trying to dial back if the car is too twitchy on rear springs that are stiffer than front.

That's what I did on my GR...

[AustinTX]

The multilink cars have a motion ratio in the back which means for equal front and rear spring rates, the rear spring rate at the tires is just 70% of the front spring rate. That is why 08+ folks should be looking at stiffer rear springs than front. Heck, I ran (slightly) stiffer rear springs on my GD.

Just because the tread width matches the wheel width doesn't mean you are getting the most out of a tire. 255's on a 10 definitely have more grip than 255's on a 9, plus the transient performance is significantly better. Don't mentally compromise your wheel width to make the build go smoother.

Adding rear bar to an STI to improve balance may help on corner entry, but it'll generally cause inside rear wheel lift which can be detrimental to the center and rear diff operation and lead to premature failure. Try keep all 4 tires on the ground through the run while adjusting.

[AustinTX]

And second Jesup16 - no amount of tire size will fix the gearing issue of the STI's for today's autocross courses. Get better at shifting :P

[dhatcher]

As far as power mods, I'm not doing a down pipe because if I get pulled over and sent to the state ref, reversing an intake and exhaust and going back to stock tune is easy for me. Swapping out the down pipe with (what I've heard) are very fragile studs is not my thing. Maybe I will change my mind down the road.

I ended up going with the Tein Monosports which retain the inverted monotube design of oem (and as I understand, just generally handle side loading better) and are 10K rated all around (have to remember it's still a daily driver and I didn't wanna go balls to the wall stiff. hopefully 10k is enough to keep the rear wheels planted). I wanted to spend more money on coilovers but, having to drop an extra $1000 on killer b oil pan, baffle, pickup and an iag competition series aos set me back in the budget more than I wanted.

I ran 255's on my 17x8 wheels on my wrx and I never felt like I didn't have enough grip. If I end up feeling like 265 on a 9.5" wide wheel is not enough I might consider jumping up to the 10's.

And by no means do I think I'm not gonna have to shift to 3rd. I fully expect it and can tell just from my commute to work, the car is gonna require more shifting than the wrx. I just don't want to make already short gears, shorter. One of the problems I always felt the wrx had was that in some elements of the course it got just a little out of the power band in 2nd gear. Now I might've been able to help that by going to 18's but, maybe with the STI (hoping) having to drop down into 2nd at higher rpms when I need to get back on the throttle will work to an advantage. I'll have fun figuring it out

All things considered, it's shaping up to be a fun season of autocrossing regardless. I'll report back on how things go this season with the initial build.

[dhatcher]

Also, opinions on running Motul 300V 10-40w in the sti? I see it's an oil designed for racing. I haven't looked into it's ZDDP content but, I did run Redline in my WRX for a while until the cat wet the bed and had to be replaced (under warranty luckily). The cat going south may have just been an unfortunate coincidence but, it's made me twitchy about race oils in a daily driver.

[littledrummerboy]

@AustinTX good points about the multilink setup and the effective rate -- my GD days are showing lol. I'll keep that in mind for my future setup.

The thing about wheel width is that being a dd and auto-x car, stretching out the tire to max wheel width doesn't really help with the dd part. I can see what you mean on a dedicated set of wheels -- though from the feel I try to get, for 255 I think paring down super speedy initial response from sitting at the max 10" for a little more contact patch is worth going to 275 on a 10". Though sidewall stiffness plays a role there too.

...its a tricky balance... and personal preference too I guess.

@dHatcher. I just run Motul X-cess 5w40 now and even back to my old tuned WRX days. Holds up well for dd and auto-x/track.

[dhatcher]

Yeh 265 is the limit for STU. We'll see what happens with the 9.5s.I did read about a guy autocrossing a challenger down in Vegas who said he actually got faster when he went back down to 295 (i think it was that) from 315. So there can be a point of being too wide. Not sure that's true for the VA platform but, it was interesting to read and put in the memory bank for "what if."

Someone told me the EJ25 temps get too hot for 5-*W oils and cause them to sheer. I figure I'm probably gonna run 5-30 from nov-feb and then march-oct run the 10-40.

[AustinTX]

Originally Posted by dhatcher

As far as power mods, I'm not doing a down pipe because if I get pulled over and sent to the state ref, reversing an intake and exhaust and going back to stock tune is easy for me.

Not so sure you will get away with the reflash back to stock. Subaru dealers are well aware of what to look for mod wise, and Subaru STI ECU's have been reporting reflash counts since 2015. They will know what you've been doing - just a matter of whether they want to help you or not.

[AustinTX]

Motul Xcess 5W40 is arguably the best oil for the turbo Subarus. I would not go thicker - especially on a dual AVCS motor. They do have oil starvation issues when running near the rev limiter at high cornering forces. A bigger oil pan might help with that, but thicker oil will likely make it worse.

[dhatcher]

Originally Posted by AustinTX

Not so sure you will get away with the reflash back to stock. Subaru dealers are well aware of what to look for mod wise, and Subaru STI ECU's have been reporting reflash counts since 2015. They will know what you've been doing - just a matter of whether they want to help you or not.

The stock flash isn't for the dealer (I'm aware they've got all the data logged). It's incase I receive a sticker to visit the state ref in California (if a cop decides your mods aren't legal, you receive a state ref ticket of sorts that requires you visit a state inspection place that will look to see if your car is stock. It generally means putting all non CARB approved goop back to OEM and flashing the tune back to stock so you can pass a smog).

[littledrummerboy]

Originally Posted by dhatcher

Yeh 265 is the limit for STU. We'll see what happens with the 9.5s.I did read about a guy autocrossing a challenger down in Vegas who said he actually got faster when he went back down to 295 (i think it was that) from 315. So there can be a point of being too wide. Not sure that's true for the VA platform but, it was interesting to read and put in the memory bank for "what if."

Someone told me the EJ25 temps get too hot for 5-*W oils and cause them to sheer. I figure I'm probably gonna run 5-30 from nov-feb and then march-oct run the 10-40.

Really? 265 is the limit on STU? I don't remember seeing that -- I better re-read and see. I haven't been hassled about it, but it could also be my officials haven't been bothered to check.

The 5 is fine as you'll never be running straight after a deep cold start anyway. There's ample time to get the oil warm and stay warm. 40 is fine. I also run 5w30 in winter/early spring (Motul X-clean EFE) -- when auto-x season is done.