Setup for Ecoboost PP in STU

I started autocrossing my Performance Pack Ecoboost this summer and seem to have done pretty well starting in the novice class. The car is severely limited by tires which are currently 275/35/20 Sumitomo HTR-Z III's but it doesn't really matter since I'm just starting out. The car seems very capable but I want to know what would be a good setup for the car so that I can follow it once I begin to mod for my class.

The class I intend to race in is STU, there doesn't seem to be any STP cars in my area and the car seems to do well enough to be competitive in STU given practice to work on the driver mod.

The car is already on BC Racing coilovers and has a straight piped catback along with 20x10 Rovos Durban wheels with the previously mentioned 275/35 tires. I only plan to race locally so nationals is out of the question if I even get myself and the car competitive enough in the class.

So far I'm looking at Whiteline sway bars and a second set of wheels to throw on for event days. After that I'm not sure where to mod the car other than maybe a tune that works for the class. My thoughts for an ideal wheel and tire setup would be 19x10.5 squared and probably a 285/35 tire although I'm limited on price to about 250 per tire so I don't know what a good option would be.

In the mean time I will probably be playing with front camber and tire pressures to see what I can do to help grip in the bendy sections.

Do you all have some ideas on a decent tire and where I should mod next as well as my current plans? I'm wide open for suggestions.

Also, can I not upgrade the intercooler within the STU class? I don't see it mentioned in the guidelines I saw.

I would run in CAM-C instead of STU. The index is almost exactly the same as STP, and the mods available are many.

Based on your signature picture, I would raise your car about 1" from where you are at to improve handling/geometric consistency. I would focus on getting some RE71R tires (if you get 10.5" squared, you'll want 305 width tires) first and then work on driving. You'll improve more from those than any part you put on. The only exception to that is a Schroth Quickfit harness. It makes a tremendous difference. I'd also go for a much more handling-focused suspension than BC coilovers. Their rates are wonky.

Upgrading Brake pads , rotors and brake fluid should go on your list . Rear sway bar maybe depending upon how stiff your PP 1 is . Bigger intercooler definitely .

BmacIL said:

I would run in CAM-C instead of STU. The index is almost exactly the same as STP, and the mods available are many.

Based on your signature picture, I would raise your car about 1" from where you are at to improve handling/geometric consistency. I would focus on getting some RE71R tires (if you get 10.5" squared, you'll want 305 width tires) first and then work on driving. You'll improve more from those than any part you put on. The only exception to that is a Schroth Quickfit harness. It makes a tremendous difference. I'd also go for a much more handling-focused suspension than BC coilovers. Their rates are wonky.

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I wouldn't have anyone to run against according to what I have seen from recent event attendees in Cam-C, most of the new muscle is currently in FS.

As far as the ride height, the car is no longer that low, my current tires wouldn't even allow the car to move if it were still that low. It's now down about 2"-2.5" from stock on all four corners.

RE71's are out of my price range. I can't justify spending that much on a tire, 250 is already stretching what I would want to pay, do you have any suggestions for another tire that fits that range? How do the Nitto NT05's do with autocross situations?

If I change anything on the coilovers then I'll probably change the springs, so what would you suggest as a good rate? I have heard that Swift offers a good set available for the BC's.

Brian V said:

Upgrading Brake pads , rotors and brake fluid should go on your list . Rear sway bar maybe depending upon how stiff your PP 1 is . Bigger intercooler definitely .

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Brakes have actually been in the conversation, just forgot them. Any recommendation on brand of pads, rotors, and type of brake fluid? DOT4?

The Whiteline sways being adjustable is one reason I looked at them so adjusting would be an optionfor tuning the suspension.

Is the intercooler change legalin STU though?

zacpounds said:

I wouldn't have anyone to run against according to what I have seen from recent event attendees in Cam-C, most of the new muscle is currently in FS.

As far as the ride height, the car is no longer that low, my current tires wouldn't even allow the car to move if it were still that low. It's now down about 2"-2.5" from stock on all four corners.

RE71's are out of my price range. I can't justify spending that much on a tire, 250 is already stretching what I would want to pay, do you have any suggestions for another tire that fits that range? How do the Nitto NT05's do with autocross situations?

If I change anything on the coilovers then I'll probably change the springs, so what would you suggest as a good rate? I have heard that Swift offers a good set available for the BC's.



Brakes have actually been in the conversation, just forgot them. Any recommendation on brand of pads, rotors, and type of brake fluid? DOT4?

The Whiteline sways being adjustable is one reason I looked at them so adjusting would be an optionfor tuning the suspension.

Is the intercooler change legalin STU though?

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I'm sorry, but that's still way too low to have a competent handling car. 1" drop from stock or less. The suspension geometry at your current ride height is too compromised. Swifts are pretty good but still more comfort focused. BMR Handling springs, GT350R springs or Steeda's Dual rate comp springs, all paired with a good damper, are the best choices for a handling focused car without spending $2500+ on a good set of high quality coilovers. You may be able to change springs with your BC coilovers but then you're in a total guessing game with adjustments.

NT05s are not a competitive tire for autocross either. The only two that are in sizes that work for us: RE71Rs and to a lesser extent Federal 595 RS-RR. Neither are very good for daily use but are amazing for autocross. The fact is that you have to accept not being competitive (2-5 seconds slower depending on course size) on other tires or pony up the dough. I did the former for a couple years, but it's way more fun on a grippy tire.

Happy to help you with suspension if you want.

zacpounds said:

Brakes have actually been in the conversation, just forgot them. Any recommendation on brand of pads, rotors, and type of brake fluid? DOT4?

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Forget about brakes - changing them isn't going to make you any faster for a long time. And fluid makes zero difference in autocross.

You have to decide between modding your for the reason of modding or modding your car to be competitive in autocross. If the latter, start with RE-71Rs, they'll give you the largest benefit vs. all the other mods listed. Only other tire in 19" size that is somewhat competitive in autocross is Nexen Nfera Sur-4G - 275 is a max width from what I remember though and you can't go wider than 285 in STU anyway.
285 Bridgestones aren't that much more expensive than your $250 limit.

285/35R19 RE71Rs are currently $288 at Tire Rack. The extra $150 is well worth it to be on competitive tires, and you can run them on wheels as wide as 11" (so your planned 10.5" wheels are perfect).

As mentioned, forget brakes, you don't generate enough braking heat in autox to need to upgrade there.

STU is limited, CAM is wide open for modifications and their classes are the same. I'd pick a class based on which one has the most local competition. Autox is more fun when you have other people in your class to compare against. Unfortunately STU is full of AWD WRX cars and those can be blisteringly fast if driven well.

NightmareMoon said:

285/35R19 RE71Rs are currently $288 at Tire Rack. The extra $150 is well worth it to be on competitive tires, and you can run them on wheels as wide as 11" (so your planned 10.5" wheels are perfect).

As mentioned, forget brakes, you don't generate enough braking heat in autox to need to upgrade there.

STU is limited, CAM is wide open for modifications and their classes are the same. I'd pick a class based on which one has the most local competition. Autox is more fun when you have other people in your class to compare against. Unfortunately STU is full of AWD WRX cars and those can be blisteringly fast if driven well.

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Yeah, all this. For me there are usually a handful of CAM cars and you'll get destroyed by well-driven STU AWD cars (Evo and WRX STi).

The RE71Rs are amazing. It completely changes how the car can be driven.

BmacIL said:

I'm sorry, but that's still way too low to have a competent handling car. 1" drop from stock or less. The suspension geometry at your current ride height is too compromised. Swifts are pretty good but still more comfort focused. BMR Handling springs, GT350R springs or Steeda's Dual rate comp springs, all paired with a good damper, are the best choices for a handling focused car without spending $2500+ on a good set of high quality coilovers. You may be able to change springs with your BC coilovers but then you're in a total guessing game with adjustments.

NT05s are not a competitive tire for autocross either. The only two that are in sizes that work for us: RE71Rs and to a lesser extent Federal 595 RS-RR. Neither are very good for daily use but are amazing for autocross. The fact is that you have to accept not being competitive (2-5 seconds slower depending on course size) on other tires or pony up the dough. I did the former for a couple years, but it's way more fun on a grippy tire.

Happy to help you with suspension if you want.

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How would changing the spring make a guessing game? I've never paid attention to spring rates so I don't really know how it really changes the dynamics of the suspension as a whole other than firmer or softer..

CVCashmere said:

Brace up the front end to better stabilize the geometry. That would include previously mentioned strut & upper K bars. Add lower K bar or PP bracing below.

that's been my current project.

CVCashmere

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What is PP bracing? I've heard of the others before but not that.

kz said:

Forget about brakes - changing them isn't going to make you any faster for a long time. And fluid makes zero difference in autocross.

You have to decide between modding your for the reason of modding or modding your car to be competitive in autocross. If the latter, start with RE-71Rs, they'll give you the largest benefit vs. all the other mods listed. Only other tire in 19" size that is somewhat competitive in autocross is Nexen Nfera Sur-4G - 275 is a max width from what I remember though and you can't go wider than 285 in STU anyway.
285 Bridgestones aren't that much more expensive than your $250 limit.

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Makes sense regarding the brakes, would better pads be worth it or no since I have the stock GT brakes via the Performance Pack?

I noticed the pricing for the RE71's after I posted, it might be doable if they will last me a while, I drive an hour on the highway to the events and will have to drive the distance with the wheels and tires on most likely. How many Autocross seasons will they last on a car this heavy? My friend's Miata has been on them for like 3 years but it's a lot smaller... Lol.

NightmareMoon said:

285/35R19 RE71Rs are currently $288 at Tire Rack. The extra $150 is well worth it to be on competitive tires, and you can run them on wheels as wide as 11" (so your planned 10.5" wheels are perfect).

As mentioned, forget brakes, you don't generate enough braking heat in autox to need to upgrade there.

STU is limited, CAM is wide open for modifications and their classes are the same. I'd pick a class based on which one has the most local competition. Autox is more fun when you have other people in your class to compare against. Unfortunately STU is full of AWD WRX cars and those can be blisteringly fast if driven well.

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Cam may be wide open for mods but there is nobody really in my area that is running it currently and the AWD cars have been running in a different class. The fastest car in the STU class at the last event was a 350Z with a more qualified setup than mine ran a 55.6 where I ran a 61.4, all the other cars ran about where I was with 60.XX. So I'm not too far off by what I'm seeing and from what it sounds like, tires make a huge improvement on time alone..

BmacIL said:

Yeah, all this. For me there are usually a handful of CAM cars and you'll get destroyed by well-driven STU AWD cars (Evo and WRX STi).

The RE71Rs are amazing. It completely changes how the car can be driven.

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My reply about the class is right above your quote but yes I have heard the RE71's are amazing and widely regarded as the best tire out for autocross right now. They might be doable in a 285/35/19 if they will last me a few seasons? Would throwing them on the stock 19x9's be okay by any chance? I know they are a bit wide for the wheel so that's why I ask.

zacpounds said:

How would changing the spring make a guessing game? I've never paid attention to spring rates so I don't really know how it really changes the dynamics of the suspension as a whole other than firmer or softer..



What is PP bracing? I've heard of the others before but not that.



Makes sense regarding the brakes, would better pads be worth it or no since I have the stock GT brakes via the Performance Pack?

I noticed the pricing for the RE71's after I posted, it might be doable if they will last me a while, I drive an hour on the highway to the events and will have to drive the distance with the wheels and tires on most likely. How many Autocross seasons will they last on a car this heavy? My friend's Miata has been on them for like 3 years but it's a lot smaller... Lol.



Cam may be wide open for mods but there is nobody really in my area that is running it currently and the AWD cars have been running in a different class. The fastest car in the STU class at the last event was a 350Z with a more qualified setup than mine ran a 55.6 where I ran a 61.4, all the other cars ran about where I was with 60.XX. So I'm not too far off by what I'm seeing and from what it sounds like, tires make a huge improvement on time alone..



My reply about the class is right above your quote but yes I have heard the RE71's are amazing and widely regarded as the best tire out for autocross right now. They might be doable in a 285/35/19 if they will last me a few seasons? Would throwing them on the stock 19x9's be okay by any chance? I know they are a bit wide for the wheel so that's why I ask.

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To my previous most: spring and damper match is critical for both ride and the right amount of body control on the course. If you just change springs you could easily get into a significantly over or underdamped condition, but I wouldn't be able to tell you without knowing the F vs V curves of the shocks and struts. A "right" handling car has those things well-matched. The car will feel balanced, responsive and not too sensitive to bumps in the corner.

285/35R19 do fit on 19x9s, and several guys with EB PP cars have run them with success in autocross. They're not an ideal fit, but width is more important in autocross than the best fit for response (285 on a 10 or 10.5 is ideal). As far as how long they last, well that depends on a couple things. 1) will you be regularly driving them on the street? If yes, then not much. They're very soft and will probably be done after 10k miles, maybe less. If no, then 2) they should last 2 autocross seasons if you're doing 6-8 events a season. If you do significantly more events, then expect 1 season before the tread is at/below the wear bars. As I mentioned, they are not a great street tire, and are better to have on a separate set of wheels unless your street mileage is low.

If you want to be a competitive autocrosser sell all the aftermarket suspension bits, go back to street class, and buy RE-71R's. Then take a really good autocross school such as EVO.

All that other stuff means almost nothing if you don't have competitive grip.

FYI I wore out a set of 275/35x19 RE-71R's on my 18 GT PP in 7000 miles plus MANY SCCA Pro Solos and Tours plus EVO school. By "wear out" I mean 1 - 2/32nds rear center groove tread depth and 4 - 5/32nds front center groove tread depth. I don't bother rotating. Also I'm not convinced 285's on 9 inch rims are worth any extra cost and mounting challenges. The dominant 6th Gen Camaro in FS at top level events this year runs 265's on his 8.5 inch fronts plus a big front bar and still has oversteer issues on at least one Pro Solo site with 285's on his 9.5 inch rears. Even with a big front bar and 275's square my GT PP wants to oversteer under power. The real solution for tires if you want to be competitive is two sets of wheels with long lasting daily driving tires on one set and competition tires on the other.

Anyway enough preaching from an old guy who used to be fast.

DickR said:

If you want to be a competitive autocrosser sell all the aftermarket suspension bits, go back to street class, and buy RE-71R's. Then take a really good autocross school such as EVO.

All that other stuff means almost nothing if you don't have competitive grip.

FYI I wore out a set of 275/35x19 RE-71R's on my 18 GT PP in 7000 miles plus MANY SCCA Pro Solos and Tours plus EVO school. By "wear out" I mean 1 - 2/32nds rear center groove tread depth and 4 - 5/32nds front center groove tread depth. I don't bother rotating. Also I'm not convinced 285's on 9 inch rims are worth any extra cost and mounting challenges. The dominant 6th Gen Camaro in FS at top level events this year runs 265's on his 8.5 inch fronts plus a big front bar and still has oversteer issues on at least one Pro Solo site with 285's on his 9.5 inch rears. Even with a big front bar and 275's square my GT PP wants to oversteer under power. The real solution for tires if you want to be competitive is two sets of wheels with long lasting daily driving tires on one set and competition tires on the other.

Anyway enough preaching from an old guy who used to be fast.

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This!

I value what some of my mods have done for the driving experience more than a better index, so I accept a steeper slope and potentially tougher competition in CAM-C, but as stated, by far the least expensive way to be competitive is to go back to stock and buy RE71Rs and a Strano rear bar.

BmacIL said:

To my previous most: spring and damper match is critical for both ride and the right amount of body control on the course. If you just change springs you could easily get into a significantly over or underdamped condition, but I wouldn't be able to tell you without knowing the F vs V curves of the shocks and struts. A "right" handling car has those things well-matched. The car will feel balanced, responsive and not too sensitive to bumps in the corner.

285/35R19 do fit on 19x9s, and several guys with EB PP cars have run them with success in autocross. They're not an ideal fit, but width is more important in autocross than the best fit for response (285 on a 10 or 10.5 is ideal). As far as how long they last, well that depends on a couple things. 1) will you be regularly driving them on the street? If yes, then not much. They're very soft and will probably be done after 10k miles, maybe less. If no, then 2) they should last 2 autocross seasons if you're doing 6-8 events a season. If you do significantly more events, then expect 1 season before the tread is at/below the wear bars. As I mentioned, they are not a great street tire, and are better to have on a separate set of wheels unless your street mileage is low.

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Sounds like I should talk with BC and get their recommendation or see if they are willing to relinquish those charts. I could always increase the spring rate by adjusting the preload too though, right? If I need to go softer then I would need to replace the spring.

That's probably okay tread life wise. I would only use them for a few events a year and driving to and from them since they would be a spare setup just for events. I might go with the 595's for the first season so that my tires don't completely mask my poor driving skills. Learning to handle the lack of grip is also important, right?

DickR said:

If you want to be a competitive autocrosser sell all the aftermarket suspension bits, go back to street class, and buy RE-71R's. Then take a really good autocross school such as EVO.

All that other stuff means almost nothing if you don't have competitive grip.

FYI I wore out a set of 275/35x19 RE-71R's on my 18 GT PP in 7000 miles plus MANY SCCA Pro Solos and Tours plus EVO school. By "wear out" I mean 1 - 2/32nds rear center groove tread depth and 4 - 5/32nds front center groove tread depth. I don't bother rotating. Also I'm not convinced 285's on 9 inch rims are worth any extra cost and mounting challenges. The dominant 6th Gen Camaro in FS at top level events this year runs 265's on his 8.5 inch fronts plus a big front bar and still has oversteer issues on at least one Pro Solo site with 285's on his 9.5 inch rears. Even with a big front bar and 275's square my GT PP wants to oversteer under power. The real solution for tires if you want to be competitive is two sets of wheels with long lasting daily driving tires on one set and competition tires on the other.

Anyway enough preaching from an old guy who used to be fast.

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They had a school the weekend before my first event but I wasn't aware, I might look into it though since it would helpful for obvious reasons. The local SCCA novice class actually provides instructors during the runs so that was very helpful during my runs.

My car currently understeers a lot but this could be due to my poor driving line and lack of throttle use on exits which I was starting to work on during my last runs which improved my times. The car felt better balanced on those runs too.

zacpounds said:

Sounds like I should talk with BC and get their recommendation or see if they are willing to relinquish those charts. I could always increase the spring rate by adjusting the preload too though, right? If I need to go softer then I would need to replace the spring.

That's probably okay tread life wise. I would only use them for a few events a year and driving to and from them since they would be a spare setup just for events. I might go with the 595's for the first season so that my tires don't completely mask my poor driving skills. Learning to handle the lack of grip is also important, right?



They had a school the weekend before my first event but I wasn't aware, I might look into it though since it would helpful for obvious reasons. The local SCCA novice class actually provides instructors during the runs so that was very helpful during my runs.

My car currently understeers a lot but this could be due to my poor driving line and lack of throttle use on exits which I was starting to work on during my last runs which improved my times. The car felt better balanced on those runs too.

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The BC rates are odd in that the fronts are really, really stiff compared with the rear. There's your understeer. I don't really trust a company that sells a kit with that large of an imbalance, nor grasps relative ride frequencies. It'll ride ok, but the handling will be odd/poor. For the hard parkers, it's a good option. Anyone serious about handling isn't even looking there.