Best tires and rim size for racing

[Cruising68]

800 is a great goal on forged intervals. I’d be less concerned about the drivetrain than I would be about steering and suspension. Hard cornering can easily exceed design specs on things like control arms and end links. I’ve seen a 130mph track wreck from a snapped control arm. Totaled car and injuries. It’s a pretty heavy vehicle to begin with so hard cornering forces abound. The control arms in my CTSV were bigger than my arms and I’m not small

I think you are on track with the cornering being more of a concern than high HP acceleration. You can improve aero as you mentioned. I’m actually surprised by the aerodynamic efficiency of what is basically a box.

Good news is the ST appears to be a damn safe chassis!


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[bbbart]

800 is a great goal on forged intervals. I’d be less concerned about the drivetrain than I would be about steering and suspension. Hard cornering can easily exceed design specs on things like control arms and end links. I’ve seen a 130mph track wreck from a snapped control arm. Totaled car and injuries. It’s a pretty heavy vehicle to begin with so hard cornering forces abound. The control arms in my CTSV were bigger than my arms and I’m not small

I think you are on track with the cornering being more of a concern than high HP acceleration. You can improve aero as you mentioned. I’m actually surprised by the aerodynamic efficiency of what is basically a box.

Good news is the ST appears to be a damn safe chassis!

Agreed. Seeing the aftermath of Explorer wrecks is very confidence inspiring, these things are tanks.

Pretty much have everything covered except control arms and confidence-inspiring coilovers. I had front end-links replaced about 300 miles ago with the Steeda's and will be looking checking to see if my rear-end links are aftermarket or stock soon.

I'm waiting to see the reviews on the Speedlogix rear control arms to see if they'll be ideal for my air suspension setup or whether I would have to switch to coilovers.

Apparently there is an option for JRZ coilovers out there but it's looking like $10k+ so hopefully Bilstein comes out with something in between the quality of the BC Racing BR and JRZ RS Pro 3.

Looking into control arms at the moment. I just spoke with Speedlogix today and am planning on ordering a front control arm with the spherical bushings within the next couple months.

 

[UNBROKEN]

Avoid everything Speedlogix makes like the plague. They build trash.

 

[bbbart]

Avoid everything Speedlogix makes like the plague. They build trash.

They redesigned the front control arms to be slimmer so I'm hoping that would solve any issues. We really need to see a review of their updated version to know for sure.

I really don't like to see people having issues with earlier versions of their parts, but if it can happen to Steeda, it can happen to anyone imo. I'm acutely aware of the drama surrounding their business.

At this point, I'm thinking that even if it's exactly the same as stock, the billet materials up front should at the very least offer peace of mind if plowing through under steer on a rough road and or improve the steering feel.

 

[2020FordRaptor]

Agreed. Seeing the aftermath of Explorer wrecks is very confidence inspiring, these things are tanks.

Pretty much have everything covered except control arms and confidence-inspiring coilovers. I had front end-links replaced about 300 miles ago with the Steeda's and will be looking checking to see if my rear-end links are aftermarket or stock soon.

I'm waiting to see the reviews on the Speedlogix rear control arms to see if they'll be ideal for my air suspension setup or whether I would have to switch to coilovers.

Apparently there is an option for JRZ coilovers out there but it's looking like $10k+ so hopefully Bilstein comes out with something in between the quality of the BC Racing BR and JRZ RS Pro 3.

Looking into control arms at the moment. I just spoke with Speedlogix today and am planning on ordering a front control arm with the spherical bushings within the next couple months.

Stay away from Speedlogix. Can’t emphasize that enough.

They redesigned the front control arms to be slimmer so I'm hoping that would solve any issues. We really need to see a review of their updated version to know for sure.

I really don't like to see people having issues with earlier versions of their parts, but if it can happen to Steeda, it can happen to anyone imo. I'm acutely aware of the drama surrounding their business.

At this point, I'm thinking that even if it's exactly the same as stock, the billet materials up front should at the very least offer peace of mind if plowing through under steer on a rough road and or improve the steering feel.

Steeda has been rushing undeveloped products to the market. Quality producers like Fenfab don’t do that, so it’s not “if it can happen to Steeda it can happen to anyone.”

 

[2020FordRaptor]

100% agree with all of your points. I'm not trying to be the first one to hit 200mph unless there's a tempting financial incentive. All the data points to it being a reasonable expectation with all the new parts. I just want to make sure I'm overbuilding it for my goal which is a reliable 800whp. We believe 800whp is a very safe number for the new block and have the fueling and turbos to push it up well above 1000whp. 800whp for several months will likely expose some more weak links, whether that's the differential, crankshaft, driveshaft, or something else, remains to be seen.

1,000whp is a way too ambitious for stock frame turbos.

 

[UNBROKEN]

1,000whp is a way too ambitious for stock frame turbos.

He has Kevin’s old ST

 

[2020FordRaptor]

He has Kevin’s old ST

Oh I remember now. Forgot about that. OP probably should’ve mentioned that for us short term memory folks But still, me statement stands because Kevin had a custom single turbo setup right?

 

[bbbart]

Oh I remember now. Forgot about that. OP probably should’ve mentioned that for us short term memory folks But still, me statement stands because Kevin had a custom single turbo setup right?

It has two Xona 5451S turbos. The plan is to downsize to 4951S. Not trying to ever run a tune higher than 825whp | 825lb/ft until someone else pushes the engine further and finds the limit though so I was hoping to get the flattest power curve that could make 800whp reliably.

https://xonarotor.com/products/xona-rotor-49-51s-ball-bearing-turbocharger

https://www.maperformance.com/produ...-ultra-high-flow-turbocharger-280-570hp-12010

 

[boiler662]

I read your initial post a few times and maybe I missed it, what kind of racing are you doing? Real track racing or finding a twisty back road?

 

[bbbart]

I read your initial post a few times and maybe I missed it, what kind of racing are you doing? Real track racing or finding a twisty back road?

Ideally both. I'm being told I'm getting ahead of myself and should focus on suspension before tires though.

I don't mind it being slow for a track car, but want to handle reasonably well and increase the G-force by 0.1-0.2 on a skidpad test without switching from the air suspension to coilovers ideally.

 

[boiler662]

What rules do the groups around you have for SUVs? Some don't allow them at all. For something like the Explorer brakes and suspension for sure are first.

 

[bbbart]

What rules do the groups around you have for SUVs? Some don't allow them at all. For something like the Explorer brakes and suspension for sure are first.

Sounds about right. I will look into it closer to the completion date.

The brakes are great but the air suspension will never outperform coils; hoping we can tune it to perform better without overstressing the bags. If we can get them to be at a high PSI while lowered, it should reduce the body roll but that's a big if.

 

[UNBROKEN]

Sounds about right. I will look into it closer to the completion date.

The brakes are great but the air suspension will never outperform coils; hoping we can tune it to perform better without overstressing the bags. If we can get them to be at a high PSI while lowered, it should reduce the body roll but that's a big if.

Are the bags isolated side to side?

 

[DaHuntah]

I would love to see a video of one of these taking a corner at 150 MPH!

 

[bbbart]

I would love to see a video of one of these taking a corner at 150 MPH!

Shouldn't be too long. Another member has an ST without a sunroof on JRZ RS 3 Pro coilovers that would be perfect for this kind of driving. The absolute best setup for grip and cornering performance.

 

[boiler662]

Shouldn't be too long. Another member has an ST without a sunroof on JRZ RS 3 Pro coilovers that would be perfect for this kind of driving. The absolute best setup for grip and cornering performance.

I'm trying to figure out where your going to do this? Road America has the long straight but I doubt its long enough with the hill to hit 150 and you will have to brake going into T1. IndyCar's without the halo were hitting 180 at the braking point 7 years ago the GTP cars are hitting 190 in their current form. I doubt the Explorer will only be 30-40 mph down on them. Even at the kink after the carousel you wont have the downforce to hold any kind of speed through there without massive understeer.

Or are you talking about taking it to an oval? There really are not a lot of US tracks that have high speed sweeping corners where full on race cars are taking them at 150 mph let alone an SUV, running the roval at Daytona or Charlotte would be your best bet, or maybe Indy coming going into the T1-T2 short chute before you go back into the twisty bits before S/F.

As someone who tracks a 3,9XX pound sedan I applaud you for going down the road less traveled and look forward to seeing your videos.

 

[Cruising68]

I'm trying to figure out where your going to do this? Road America has the long straight but I doubt its long enough with the hill to hit 150 and you will have to brake going into T1. IndyCar's without the halo were hitting 180 at the braking point 7 years ago the GTP cars are hitting 190 in their current form. I doubt the Explorer will only be 30-40 mph down on them. Even at the kink after the carousel you wont have the downforce to hold any kind of speed through there without massive understeer.

Or are you talking about taking it to an oval? There really are not a lot of US tracks that have high speed sweeping corners where full on race cars are taking them at 150 mph let alone an SUV, running the roval at Daytona or Charlotte would be your best bet, or maybe Indy coming going into the T1-T2 short chute before you go back into the twisty bits before S/F.

As someone who tracks a 3,9XX pound sedan I applaud you for going down the road less traveled and look forward to seeing your videos.

Funny you mention Road America. I blew the motor on my 700hp CTSV on the back straight. Guy behind me had video. Threw a rod at 150 plus. Whole rear end was in flames enough to melt the tail lights. Flames went out when I dropped speed. When I got to the pits I saw a fist sized hole in the block. That was an expensive weekend!

If he’s got 800rwhp I’m thinking 160+ is not out of the question if lowered with some aero improvements. The AWD helps too as I had enough power to roast the rear tires anytime under 60mph. Awd should pull him out of the corners pretty good imo.


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[boiler662]

Funny you mention Road America. I blew the motor on my 700hp CTSV on the back straight. Guy behind me had video. Threw a rod at 150 plus. Whole rear end was in flames enough to melt the tail lights. Flames went out when I dropped speed. When I got to the pits I saw a fist sized hole in the block. That was an expensive weekend!

If he’s got 800rwhp I’m thinking 160+ is not out of the question if lowered with some aero improvements. The AWD helps too as I had enough power to roast the rear tires anytime under 60mph. Awd should pull him out of the corners pretty good imo.


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He may hit 160 at the braking point but no way he is taking T1 at 150 mph. Outside the rovals I don't see a track in the country where many cars let alone an suv takes a corner at 150 mph. The bigger issue will be if any of the HPDE orgs even let him in.

This is what my local group says about SUVs
"Sport Utility Vehicles: track facilities do NOT allow some sport SUVs to run on track, the simple formula is the factory specified vehicle track width needs to be at least wider than the factory specified height of the vehicle. Track width: the distance between the centerline of two wheels on the same axle. (front axle or rear axle) "

Keep in mind they say FACTORY spec not whatever you have it lowered to the day of the event. I would assume Chin and others are probably in the same boat.

Google says our factory height is 69.8 and track width is 66.9.

 

[Cruising68]

He may hit 160 at the braking point but no way he is taking T1 at 150 mph. Outside the rovals I don't see a track in the country where many cars let alone an suv takes a corner at 150 mph. The bigger issue will be if any of the HPDE orgs even let him in.

This is what my local group says about SUVs
"Sport Utility Vehicles: track facilities do NOT allow some sport SUVs to run on track, the simple formula is the factory specified vehicle track width needs to be at least wider than the factory specified height of the vehicle. Track width: the distance between the centerline of two wheels on the same axle. (front axle or rear axle) "

Keep in mind they say FACTORY spec not whatever you have it lowered to the day of the event. I would assume Chin and others are probably in the same boat.

Google says our factory height is 69.8 and track width is 66.9.

Agree on cornering speed for sure. Didn’t even think about the height restriction although it makes sense. Heck, my CTSV was setup for track use lowered with stiff sway bars and it was still a pig in the corners at over 4klbs. ST has to have a higher center of gravity and all the weight. I’ve seen everything from C8’s to hellcats to moms minivan at the 1/4 mile but not on road courses. I believe the non-competition weekend events would allow an ST.


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