2023 Civic Si Spring Rates, Motion Ratio, Ride Frequencies, Autocross

[eromani]

This thread is relevant to my interests!

Just picked up my 23 Si back in May and have run it in my first autocross events ever over the summer - the second was just this past Saturday at Summit Point in WV.

My performance on Saturday was, to say the least, disappointing. Last in street class, over 12 seconds slower than the fastest car (a heavily modded ND Miata)...and most embarrassing was the 2005 Toyota Corolla that finished two places above me . To be fair, he at least had performance wheels and tires on the car, and some kind of free flowing exhaust...but still, getting beat by an almost 10 year old Corolla is pretty humiliating.

I'm still bone stock, including riding on the standard Goodyear all-seasons. Needless to say, the car is awful when it's sliding / under-steering around every corner. I also realize that as the driver, I have A LOT to learn about the sport, driving technique, etc. (My 21 y/o son, who autocrosses a slightly modified NB Miata, told me that the "driver mod" is the most important!)

But I also know that if I want any chance to stop finishing close to dead last, I need to make some changes. Here is what I'm thinking:

1. lightweight wheels and summer performance tires (looking at Konig Dekagram 18 x 8.5 wheels; not sure about tires yet, but slightly wider 245/40 w/ ~300 tread wear as I want to get a couple years out of them if possible - open to suggestions?)
2. rear sway bar (thinking about SiriMoto 20mm)
3. rear motor mount (but I think this will push me out of Street Class into STH so may not want to do this)
4. high volume air intake (PRL)
5. exhaust (looking at the MAP catback "street" version)

Ultimately I need to decide if dropping around $3500 on the above mods is worth it. I'd hate to spend all that only to find out that my skills on the autocross track are just not going to improve enough to take full advantage of the upgrades.

Going to follow this thread and excited to learn more about autocrossing the Si.

Glad you're getting to autocross the car!
Here is my perspective on a few things...

1. (Fact, not perspective) To stay in street class, you have to stick with the same wheel width, and within 1" of OE wheel diameter. So you can do 17x8 and put 245 or 255 tires on. 300tw is a pretty good place to start.

2. I would try to stay in GS for a while until you are driving beyond the capabilities of your car and need more. So I wouldn't do the motor mount yet. Order of importance for autocross is tires, wheels, suspension (springs/shocks, anti-roll bars, alignment), then bushings/bracing etc. and I wouldn't touch those until you have a SOLID understanding of what and why to change, both as a driver and on the engineering side.

3. I ran my SI bone stock on all seasons for a practice event and noticed a few things. A lot of corner entry understeer, but very correctable with trail braking. Mid corner, balance is great. Able to rotate the car with throttle adjustments, no understeer. Corner exit understeer, but that's both expected from FWD and a good thing (makes it easier to drive faster). The good thing about the stock all season tires is you can drive at the limit at slower speeds and gives your brain plenty of space to analyze the car's behavior and how to adjust driver inputs. In other words, if you need to work on your driving, it's easier to do so on all-seasons.

4. If you want to go to STH eventually, then you basically need 200tw tires, a way to get 2 deg or more of negative front camber, stiffer front springs, then stiffer rear sway bar. The easiest way, but not cheapest, is coilovers with camber plates. This would make your car relatively competitive locally, but IMO the civic SI is very competitive in GS, less so in STH.

5. If you don't care about being competitive and just want to build yourself a better handling car, then by all means go to STH and have fun.

Others feel free to chime in and disagree.

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[BCinMD]

Glad you're getting to autocross the car!
Here is my perspective on a few things...

That is really useful info, and very much appreciated!

I'm looking at tires and wheels now. Just have to decide if I stick with 18 x 8 wheels as I can get a slightly wider 245/35 tires on the stock wheel size while staying within the +/- 1" of OE street class rule. Or perhaps I throw caution to the wind and go with a wider wheel and just accept the class change. I'd love to see a Civic Si on 17" wheels - curious as to how that would look. I guess it depends on what I want out of autocross in general, and I don't know the answer to that just yet.

I tend to over-analyze decisions like this, so I'll likely wait until next spring and just continue to run on the all seasons - as you suggest, it might be better for me as a total novice, to improve my skills on those.

 

[eromani]

Glad you're getting to autocross the car!
Here is my perspective on a few things...

1. (Fact, not perspective) To stay in street class, you have to stick with the same wheel width, and within 1" of OE wheel diameter. So you can do 17x8 and put 245 or 255 tires on. 300tw is a pretty good place to start.

2. I would try to stay in GS for a while until you are driving beyond the capabilities of your car and need more. So I wouldn't do the motor mount yet. Order of importance for autocross is tires, wheels, suspension (springs/shocks, anti-roll bars, alignment), then bushings/bracing etc. and I wouldn't touch those until you have a SOLID understanding of what and why to change, both as a driver and on the engineering side.

3. I ran my SI bone stock on all seasons for a practice event and noticed a few things. A lot of corner entry understeer, but very correctable with trail braking. Mid corner, balance is great. Able to rotate the car with throttle adjustments, no understeer. Corner exit understeer, but that's both expected from FWD and a good thing (makes it easier to drive faster). The good thing about the stock all season tires is you can drive at the limit at slower speeds and gives your brain plenty of space to analyze the car's behavior and how to adjust driver inputs. In other words, if you need to work on your driving, it's easier to do so on all-seasons.

4. If you want to go to STH eventually, then you basically need 200tw tires, a way to get 2 deg or more of negative front camber, stiffer front springs, then stiffer rear sway bar. The easiest way, but not cheapest, is coilovers with camber plates. This would make your car relatively competitive locally, but IMO the civic SI is very competitive in GS, less so in STH.

5. If you don't care about being competitive and just want to build yourself a better handling car, then by all means go to STH and have fun.

Others feel free to chime in and disagree.

That is really useful info, and very much appreciated!

I'm looking at tires and wheels now. Just have to decide if I stick with 18 x 8 wheels as I can get a slightly wider 245/35 tires on the stock wheel size while staying within the +/- 1" of OE street class rule. Or perhaps I throw caution to the wind and go with a wider wheel and just accept the class change. I'd love to see a Civic Si on 17" wheels - curious as to how that would look. I guess it depends on what I want out of autocross in general, and I don't know the answer to that just yet.

I tend to over-analyze decisions like this, so I'll likely wait until next spring and just continue to run on the all seasons - as you suggest, it might be better for me as a total novice, to improve my skills on those.

I will say it was really fun driving on all-seasons at the practice event. Albeit slower, but it gave me a good baseline on the car's handling.

Right now, i have 255 front, 225 rear reverse stagger on stock 8" wide wheels (yes they fit). I was going to spring for RE21RS or RT660 200tw 245's all around, but I found this set of Goodyear Eagle F1's (300tw) on craigslist for $250 total, new take-offs. Too good of a price to pass up, and who cares about rotating tires at this price! Should also help with some turn-in understeer. Next real event is 8/27, so I'll report back on how I do. Car is still 100% stock except for tires. Next season I'll go to 17x8 wheels and standard 200tw.

 

[Cbau]

I will say it was really fun driving on all-seasons at the practice event. Albeit slower, but it gave me a good baseline on the car's handling.

Right now, i have 255 front, 225 rear reverse stagger on stock 8" wide wheels (yes they fit). I was going to spring for RE21RS or RT660 200tw 245's all around, but I found this set of Goodyear Eagle F1's (300tw) on craigslist for $250 total, new take-offs. Too good of a price to pass up, and who cares about rotating tires at this price! Should also help with some turn-in understeer. Next real event is 8/27, so I'll report back on how I do. Car is still 100% stock except for tires. Next season I'll go to 17x8 wheels and standard 200tw.

Did you do any more mods to the car? I'm currently in gs as well, running all stock. Looking to get 200tw tires eventually and whiteline sway bar. Also how often do you get an alignment?

 

[eromani]

Did you do any more mods to the car? I'm currently in gs as well, running all stock. Looking to get 200tw tires eventually and whiteline sway bar. Also how often do you get an alignment?

Just tires, nothing else yet. I did pretty well in GS, but got beat by a GTI. I do my own alignments. I got as much neg camber as I could by pulling the strut pin. Ended up at -1 on driver side, -0.9 passenger. Running slight toe out, about 1.5mm total toe. Only did alignment once. My Mustang that my wife drives though I had to align 3 times from suspension changes we've made. That car is in CAMC. We finally got spring rates sorted out.

 

[Cbau]

Just tires, nothing else yet. I did pretty well in GS, but got beat by a GTI. I do my own alignments. I got as much neg camber as I could by pulling the strut pin. Ended up at -1 on driver side, -0.9 passenger. Running slight toe out, about 1.5mm total toe. Only did alignment once. My Mustang that my wife drives though I had to align 3 times from suspension changes we've made. That car is in CAMC. We finally got spring rates sorted out.

Awesome! I admire your ability to do your own alignments. I've never done it before so plan to take it to a professional haha. Got any videos of your autox runs?

 

[eromani]

Did you do any more mods to the car? I'm currently in gs as well, running all stock. Looking to get 200tw tires eventually and whiteline sway bar. Also how often do you get an alignment?

Also having driven in stock form, I'm convinced I don't need anymore rear bar. I'm easily getting lift-off or trail brake oversteer on stock bars. In fact, i ruined my last run at last event because I ended up drifting tail-out around an entire corner by accident.

Yes there's corner entry understeer...but changing one bar only changes the balance mid-corner, not on entry in my experience. I've been able to overcome it by trail braking and managing weight transfer
YMMV

 

[eromani]

Awesome! I admire your ability to do your own alignments. I've never done it before so plan to take it to a professional haha. Got any videos of your autox runs?

Sadly no video! Next season for sure. Just figured out how to mount a camera safely in the position i want.

 

[nttran98]

Did you have to undo the exhaust hanger to get the sway bar in/out?
Thank you!

 

[absolude]

Trying to revive this thread since it contains a lot of good advice from experienced contributors, whom opinion I'd like to hear.
I installed the type R sway bar on my 2023 Si and the result wasn't as clear cut as in previous Hondas I modified.
The "car just wants to corner" feel wasn't as pronounced as I've experienced before.
The improvement I noticed was more in sudden changes of direction, something like a pothole avoidance move.
There is a drawback though, car seems a bit darty, the correction after such sudden moves has to be equally sudden and precise. I have no problem with that but it takes away a bit from the ultra stable feel this chassis has.

My question is, going ahead and installing the Type R springs will help with the darty feel or make it worse? Will the Type R springs bring back a more balanced, stable behaviour/feel?

I guess I've come to learn any mod to an already great platform has to be done with careful consideration...

 

[rui]

Trying to revive this thread since it contains a lot of good advice from experienced contributors, whom opinion I'd like to hear.
I installed the type R sway bar on my 2023 Si and the result wasn't as clear cut as in previous Hondas I modified.
The "car just wants to corner" feel wasn't as pronounced as I've experienced before.
The improvement I noticed was more in sudden changes of direction, something like a pothole avoidance move.
There is a drawback though, car seems a bit darty, the correction after such sudden moves has to be equally sudden and precise. I have no problem with that but it takes away a bit from the ultra stable feel this chassis has.

My question is, going ahead and installing the Type R springs will help with the darty feel or make it worse? Will the Type R springs bring back a more balanced, stable behaviour/feel?

I guess I've come to learn any mod to an already great platform has to be done with careful consideration...

That is interesting and useful feedback. Thanks for sharing.
What is the difference in diameter between the FE5 and FK8 rear sway bars? I'd bet it's smaller than the difference between your previous car's bar and the FK8 bar.

 

[eromani]

Trying to revive this thread since it contains a lot of good advice from experienced contributors, whom opinion I'd like to hear.
I installed the type R sway bar on my 2023 Si and the result wasn't as clear cut as in previous Hondas I modified.
The "car just wants to corner" feel wasn't as pronounced as I've experienced before.
The improvement I noticed was more in sudden changes of direction, something like a pothole avoidance move.
There is a drawback though, car seems a bit darty, the correction after such sudden moves has to be equally sudden and precise. I have no problem with that but it takes away a bit from the ultra stable feel this chassis has.

My question is, going ahead and installing the Type R springs will help with the darty feel or make it worse? Will the Type R springs bring back a more balanced, stable behaviour/feel?

That's a tough question to answer! I believe the car in stock form is really good. The biggest difference for me was tires. I ran 245 front and 225 rear in reverse stagger and that got me the balance I wanted on stock suspension. From there, if I wanted better track performance, I would get more aggressive alignment, proportionally increase ride frequency, and stiffen some bushings (in that order). Increasing ride stiffness means higher spring rates, and thus better dampers. And sway bars. Combined with needing ~3deg of neg camber, I'd probably just go to coilovers with camber plates so I can also corner balance the car.

So I'm at an all or nothing kind of spot right now...just changing sway bars without springs and dampers won't change corner entry understeer as much as it will midcorner. But I drive FWD autocross so there's not much midcorner for me, so springs and dampers and ALIGNMENT will be better for that since I need all the spring rate I can get to keep the camber from changing too much....

If i just used the car as a daily driver, I wouldn't change anything except tires. So it depends on your application and driving technique.

Btw, all of the above is only applicable at the limit of traction. That's why for street only driving, I wouldn't change a thing because the only thing I'll end up with is an uncomfortable car.

That's my experience anyway, YMMV

 

[absolude]

That is interesting and useful feedback. Thanks for sharing.
What is the difference in diameter between the FE5 and FK8 rear sway bars? I'd bet it's smaller than the difference between your previous car's bar and the FK8 bar.

Wow, spot on! I think the difference is about 3 mm. A lot less than the one on my 8th. gen. for sure as the Progress RSB is 22mm.
I had the same Type R bar on the 2018 Hatch and off course the difference is also at least 1 mm. more.
Thanks for giving a different perspective. Didn't think of it this way.

 

[absolude]

That's a tough question to answer! I believe the car in stock form is really good. The biggest difference for me was tires. I ran 245 front and 225 rear in reverse stagger and that got me the balance I wanted on stock suspension. From there, if I wanted better track performance, I would get more aggressive alignment, proportionally increase ride frequency, and stiffen some bushings (in that order). Increasing ride stiffness means higher spring rates, and thus better dampers. And sway bars. Combined with needing ~3deg of neg camber, I'd probably just go to coilovers with camber plates so I can also corner balance the car.

So I'm at an all or nothing kind of spot right now...just changing sway bars without springs and dampers won't change corner entry understeer as much as it will midcorner. But I drive FWD autocross so there's not much midcorner for me, so springs and dampers and ALIGNMENT will be better for that since I need all the spring rate I can get to keep the camber from changing too much....

If i just used the car as a daily driver, I wouldn't change anything except tires. So it depends on your application and driving technique.

Btw, all of the above is only applicable at the limit of traction. That's why for street only driving, I wouldn't change a thing because the only thing I'll end up with is an uncomfortable car.

That's my experience anyway, YMMV

Very valuable advice. A lot to consider.
Thank you.

 

[chopsuey34]

Trying to revive this thread since it contains a lot of good advice from experienced contributors, whom opinion I'd like to hear.
I installed the type R sway bar on my 2023 Si and the result wasn't as clear cut as in previous Hondas I modified.
The "car just wants to corner" feel wasn't as pronounced as I've experienced before.
The improvement I noticed was more in sudden changes of direction, something like a pothole avoidance move.
There is a drawback though, car seems a bit darty, the correction after such sudden moves has to be equally sudden and precise. I have no problem with that but it takes away a bit from the ultra stable feel this chassis has.

My question is, going ahead and installing the Type R springs will help with the darty feel or make it worse? Will the Type R springs bring back a more balanced, stable behaviour/feel?

I guess I've come to learn any mod to an already great platform has to be done with careful consideration...

Interesting feedback about the twitchiness and loss of stability. Are you using the FK8 for FL5 sway bar on your Si?

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