the stubborn quest to autocross an nsx, on the national stage

[shrddr]

hello folks,

i have been an avid autocrosser for 5+ years. i've competed in several kinds of cars/classes, and spent the 2009 autocross season driving a 2007 miata/mx5 at a national level in the solo/autocross and pro solo circuits. i did pretty well... several 2nd place finishes, a bonus challenge win at one of the pro solos, and 5th place in class at the national championships.

for the 2010 season, i am going to be campaigning my 2000 NSX in the B-stock (formerly A-stock) class. that is a class currently dominated by the s2000 (light, nimble, narrow) and the c4 corvette (can fit very wide tires, and torque!).

a few people around the country have tried autocrossing the NSX for fun, but no one seems to have developed one for serious autocross competition. this may be in part due to the prohibitive cost in the past, and the fact that atleast on paper... the car does seem to be an underdog compared to the competition.

i, however, do not fall in that camp. i am of the opinion that if set up right and if driven by the right driver, the car can be nationally competitive! so i intend to give it a shot

i have bugged billy (FXMD driver) and CL65 captain... our resident track experts... to get their opinions/advice on set up help... and i am glad to say things are underway! this is going to be an exciting 10 months of development, practice, local/national events... all culminating in the national championships in sept 2010.

i have started up a blog to track what i am learning, set ups, development of the car, and of course my development as a driver. follow along if you so desire

http://nsxftw.blogspot.com/

vivek

 

[docjohn]

I have auto x 'd my 96 before. What "setup" does B stock allow?.

 

[shrddr]

I have auto x 'd my 96 before. What "setup" does B stock allow?.

the stock class rules allow you to make ONLY the following changes:

- any front sway bar (cannot change the rear bar)
- any shocks (no changes to springs or ride height)
- any exhaust (cat-back)
- any tires (hoosier A6's!!)

while this may sound like a simple/short list of things to play with... getting the right balance for the car is going to involve quite a bit of experimentation. at a national level... every 1/100th of a second counts... so i am going to have to spend some time testing various combinations of tire sizes front to back, different front sway bars, shock settings, etc. i think tire selection and shock settings are going to end up being most critical because at lower speeds the car tends to understeer, but get much looser as speeds increase.

it will be easy to get this car within 1 second of the best cars in the class in the country. but finding that last second is going to be tricky, and fun

 

[docjohn]

I only had koni yellows on at the time which are weak sauces for getting to the winners circle.In general the nsx likes the longer more open courses,but you knew that.Some folks over the years have gotten 245 wide front slicks on the car.Your battle will be maximizing front grip,and imo the last few tenths may need to come from you.If you can change your inputs ever so slightly to compensate for the rear mid engine vs the front mid cars you are used to. Keep us posted.The nice thing about the stock 5 speed is the long second gear and relative increased torque say compared to the s2000. Of course if they lay out a real super tight course and you need first.....

 

[dquarasr2]

I only had koni yellows on at the time which are weak sauces for getting to the winners circle.In general the nsx likes the longer more open courses,but you knew that.Some folks over the years have gotten 245 wide front slicks on the car.Your battle will be maximizing front grip,and imo the last few tenths may need to come from you.If you can change your inputs ever so slightly to compensate for the rear mid engine vs the front mid cars you are used to. Keep us posted.The nice thing about the stock 5 speed is the long second gear and relative increased torque say compared to the s2000. Of course if they lay out a real super tight course and you need first.....

Best of luck on your quest.

The main thing that struck me the few times I autocrossed the car is that it always seemed to be in the wrong gear. Many autocross maneuvers seem to be too fast for first and not fast enough for second, at least in the 5-speed version with the stock gearset (which is all that's allowed in stock classes). If you have a six-speed you might be golden.

It seems to me that a later 3.2 model with additional torque and a six-speed would be a better choice, although if that's not really an option for you of course that's not really a choice, and not what you asked.

If I remember my rules correctly, you are allowed to make lots of changes to the car, but only if the combination of components were actually offered as a package on the car. I'm not sure about update/backdate in stock class (i.e., can you put Type-R components on the car if the year of your car is not the right one; that might be Street Prepared), but if there are any performance packages that came with your year of NSX as long as you make it EXACTLY like the model that was offered, you can run it. (For instance, if the package didn't include a leather-wrapped steering wheel, you must replace it, too. I remember my son going through this kind of thing when he built the first 2007 MS-R MX-5 in the country).

And if any equipment was optional (think weight) you can remove it, again, if there is a package that deleted that component and that package was available for your model year and you make your car EXACTLY like that offering. I don't know if any NSX's came without A/C, but if so, you can remove those components. Check the rule book to see what weight savings you can realize but still be legal for stock class. I'm thinking of things like power steering pumps, power seats, other convenience items that might have been optional that if deleted can save weight.

You can also tweak the car a lot with alignment, using some outrageous toe settings front (and rear!) to get the car to turn. Camber, too, of course.

Just noticed via your blog that you bought a Targa. Answering a question you didn't ask, might have been better to have a coupe for flexing, oh well, still sounds like a fun project.

Good luck!! Sounds intriguing! I'll follow along in the blog.

 

[jas303]

I bookmarked your blog and cannot wait to see how it will go!! I autocrossed in my town for 3 1/2 years until I sold my S2000. I did not know that they drop NSX from A Stock to B Stock, but in that case I think it would be rational for you to get a S2000 CR. It is a better car all around as far as autocross is concerned. However, I'd love to see you kick some serious butts in a NSX.

 

[shrddr]

I only had koni yellows on at the time which are weak sauces for getting to the winners circle.In general the nsx likes the longer more open courses,but you knew that.Some folks over the years have gotten 245 wide front slicks on the car.Your battle will be maximizing front grip,and imo the last few tenths may need to come from you.If you can change your inputs ever so slightly to compensate for the rear mid engine vs the front mid cars you are used to. Keep us posted.The nice thing about the stock 5 speed is the long second gear and relative increased torque say compared to the s2000. Of course if they lay out a real super tight course and you need first.....

you are right... front grip is paramount. what really helps the nsx is the 9+ degrees of caster! that makes for some spectacular camber gain as you turn the wheel and really helps the front bite and hold. i intend to run 245s on the front and 295s on the back to start with.

the nice thing about having an NA2 is the 6-speed with a 2nd gear that is actually usable for autocross.

 

[CL65 Captain]

235/40/17s on the front rub at full lock. I didn't have problems on the autocross track with them, but 245s might.

The courses that I ran this year (3x) - rest of the time spent at REAL tracks :tongue: I never got out of 1st gear. I would bounce off the rev limiter once or twice, but it was much faster than using 2nd. In addition I tried to brake as little as humanly possible to keep the momentum up and 1st helped with engine braking.

 

[shrddr]

Best of luck on your quest.

The main thing that struck me the few times I autocrossed the car is that it always seemed to be in the wrong gear. Many autocross maneuvers seem to be too fast for first and not fast enough for second, at least in the 5-speed version with the stock gearset (which is all that's allowed in stock classes). If you have a six-speed you might be golden.

i do have the 6 speed

If I remember my rules correctly, you are allowed to make lots of changes to the car, but only if the combination of components were actually offered as a package on the car. I'm not sure about update/backdate in stock class (i.e., can you put Type-R components on the car if the year of your car is not the right one; that might be Street Prepared), but if there are any performance packages that came with your year of NSX as long as you make it EXACTLY like the model that was offered, you can run it. (For instance, if the package didn't include a leather-wrapped steering wheel, you must replace it, too. I remember my son going through this kind of thing when he built the first 2007 MS-R MX-5 in the country).

And if any equipment was optional (think weight) you can remove it, again, if there is a package that deleted that component and that package was available for your model year and you make your car EXACTLY like that offering. I don't know if any NSX's came without A/C, but if so, you can remove those components. Check the rule book to see what weight savings you can realize but still be legal for stock class. I'm thinking of things like power steering pumps, power seats, other convenience items that might have been optional that if deleted can save weight.

i cannot put on any type-r parts. i also cannot take out the AC etc. the car must be in a form sold through US dealerships... and the type-r was never sold here, and there was no 2000 NSX made without an AC from the factory.

You can also tweak the car a lot with alignment, using some outrageous toe settings front (and rear!) to get the car to turn. Camber, too, of course.

Just noticed via your blog that you bought a Targa. Answering a question you didn't ask, might have been better to have a coupe for flexing, oh well, still sounds like a fun project.

Good luck!! Sounds intriguing! I'll follow along in the blog.

i've got a pretty aggressive alignment done

sure... the coupe might have been a marginally better choice... but (1) from a non-autocross perspective i wanted a targa, and (2) i honestly dont think the benefits are substantial enough to be outside the window of driver variability. on paper the s2000 CR should be quite a bit better than the AP1 and AP2 s2000's... but it really comes down to the driver... the difference is not significant enough.

 

[shrddr]

I bookmarked your blog and cannot wait to see how it will go!! I autocrossed in my town for 3 1/2 years until I sold my S2000. I did not know that they drop NSX from A Stock to B Stock, but in that case I think it would be rational for you to get a S2000 CR. It is a better car all around as far as autocross is concerned. However, I'd love to see you kick some serious butts in a NSX.

for 2010 the entire (current) A-stock is moving to B-stock. the current B-stock is merging with C-stock, and they are creating a new A-stock to fit between the current one ans super-stock.

 

[docjohn]

could you use the 99 zanardi springs which were sold in the US?

 

[CL65 Captain]

235/40/17s on the front rub at full lock. I didn't have problems on the autocross track with them, but 245s might.

The courses that I ran this year (3x) - rest of the time spent at REAL tracks :tongue: I never got out of 1st gear. I would bounce off the rev limiter once or twice, but it was much faster than using 2nd. In addition I tried to brake as little as humanly possible to keep the momentum up and 1st helped with engine braking.

 

[shrddr]

could you use the 99 zanardi springs which were sold in the US?

no. i cannot mix and match parts from different model years. i could only use the zanardi springs if i had a 99 coupe, and performed an ENTIRE conversion to use every single part that is on a zanardi... including all the cosmetic bits too (badges, seat material, etc). too much work for not enough gain

 

[shrddr]

235/40/17s on the front rub at full lock. I didn't have problems on the autocross track with them, but 245s might.

The courses that I ran this year (3x) - rest of the time spent at REAL tracks :tongue: I never got out of 1st gear. I would bounce off the rev limiter once or twice, but it was much faster than using 2nd. In addition I tried to brake as little as humanly possible to keep the momentum up and 1st helped with engine braking.

yeah... i am afraid rubbing might be an issue with 245s... not at full lock... rather under hard braking! the autocross video you posted looks painfully tight . the event i ran yesterday i got out of first within the first 4 seconds... and never had to downshift. more than enough torque to pull out of corners and kick the tail out on command.

 

[CL65 Captain]

yeah... i am afraid rubbing might be an issue with 245s... not at full lock... rather under hard braking! the autocross video you posted looks painfully tight . the event i ran yesterday i got out of first within the first 4 seconds... and never had to downshift. more than enough torque to pull out of corners and kick the tail out on command.

Oh... it will rub on the inside wall of the car too. 235s did. You would have to run spacers and then raise the car or roll the fenders for 245s. Talk to Chris at SOS as I think I read their widebody NSX runs 17x8s up front with 245s.

 

[shrddr]

Oh... it will rub on the inside wall of the car too. 235s did. You would have to run spacers and then raise the car or roll the fenders for 245s. Talk to Chris at SOS as I think I read their widebody NSX runs 17x8s up front with 245s.

i am sure it will rub at full lock... but i dont expect to ever be at full lock. i cannot change ride height or roll fenders in stock class.

 

[FXMDBilly]

The whole "235's rub at full lock" complaint is not important IMO. Like you stated, you don't intend on ever going to full lock.

I would agree with trying to stuff 245s up front. Who cares if you don't get the last 45-90*s of steering lock without rubbing. I sure hope your autoX tracks aren't tight enough where you will ever see full lock.

We run 280 width front tires on our FX750 Time Attack Car. Granted we have substantial offsets, we barely have 180-270* of lock before the tire rubs on the frame rail. Since we dont intend on going past that on track, its far worth the benefits.

Also get the biggest front bar you can find.


0.02

Billy

 

[R13]

The biggest issue may be front tire clearance since the wheels must be the same width, diameter and within like 5mm of stock offset in the stock classes. Of course, I haven't gone and measured the fattest tire that might fit either.

(FYI for the rest, the shocks can only be double adjustable...so no coilovers, etc.)

I run an MR2 Turbo in what will soon be C-Stock, but I have messed around with my '92 NSX as well (street tires only so far). I was actually pleasantly surprised with how composed it was even on a fairly tight course. Of course, it was half of the run in 1st gear and 2nd is way too tall in the 5spd to be really effective, but I think, as you say, a great driver in a well set-up car might do some damage.

I'm not sure how you're gonna fare against the S2Ks and C4s, but I am very curious to see.

Good luck!

 

[shrddr]

Also get the biggest front bar you can find.

wouldn't that make the car too understeer prone? or is there some other consideration? what is the rationale behind running a gigantic front bar?

 

[R13]

wouldn't that make the car too understeer prone? or is there some other consideration? what is the rationale behind running a gigantic front bar?

I'm sure someone can get into more engineering detail, but that seems to work well for mid engined cars. I have a massive front bar on the MR2 based on the advice of Robert Carpenter and Sam Strano, and I have no complaints. From a user standpoint, it transitions quicker, corners flatter, and understeer can be dialed out with alignment, tire pressure and damping adjustment.

 

[shrddr]

I'm sure someone can get into more engineering detail, but that seems to work well for mid engined cars. I have a massive front bar on the MR2 based on the advice of Robert Carpenter and Sam Strano, and I have no complaints. From a user standpoint, it transitions quicker, corners flatter, and understeer can be dialed out with alignment, tire pressure and damping adjustment.

hmmm... i am still interested in understanding it from a more technical perspective... but it makes sense that the car would transition more stable (and thus at least be perceived faster if not in fact faster). the added benefit of more front roll resistance may be that is saves my tires from rubbing under compression. thanks for the info/advice.

 

[R13]

Ok, It's not really late this time, and I did stay at a holiday inn express last night (no really, I did).

Basically if the front end is generally stiffened and the two sides are tied to each other what you get is less transitional body roll, which enables the car to change direction faster and be more responsive in general. Yes this will sacrifice some absolute grip at the front end in a steady-state corner, but this can be dialed back out to some extent by dicking (technical term) with the tire pressures and relative shock stiffness between the front and rear.

Before and after the car does push more on street tires, but with the V710s I use on there, that goes away entirely with a little shock and pressure fiddling.

The trade off is worth it for autocross. Maybe Billy or someone can speak to how this might differ (or not) for a track car.

 

[FXMDBilly]

Basically if the front end is generally stiffened and the two sides are tied to each other what you get is less transitional body roll, which enables the car to change direction faster and be more responsive in general. Yes this will sacrifice some absolute grip at the front end in a steady-state corner, but this can be dialed back out to some extent by dicking (technical term) with the tire pressures and relative shock stiffness between the front and rear.

Before and after the car does push more on street tires, but with the V710s I use on there, that goes away entirely with a little shock and pressure fiddling.

Very well written, you have a good handle on it.

While I haven't done a ton of autocross events, I would imagine the given parameters of your class -requiring the STOCK springs and ride height, combined with 245 width front tires, you might be fighting oversteer with that big of a contact patch. At the lower speeds of autoX, many cars put the largest front tire possible on the car and utilize big bars to dial out the imbalance of the tire sizing.

While it will take testing to figure out the ideal setup, I would suggest starting with a large front bar because of your 245 front tire and especially since you will be at stock ride height and spring rates.

The big front bar will increase response, weight transfer, and result in less body roll, as well as more steady-state understeer (as R13 has stated) but those should be desireable charactersitics given your restraints. Try it then report how the car handles and adjust pressures/alignement from there.

Billy

 

[shrddr]

thanks you 2. i understand the dynamics of a bar and how it affects transients vs. steady state, but i didn't think the stock springs/ride height combined with 245s on the front would be that loose, especially considering i am going to be running 295s on the back. i was thinking the car would be too pushy even with the stock front bar on those tires. but i can see the logic in high front roll stiffness and using other parameters to adjust the handling balance.

good info!

 

[wahoo5]

I will follow your quest with interest. I have been autocrossing for about 8 years in everything from a Mustang Cobra to a Crossle 50F Formula Ford. I have only autocrossed my '00 NSX once earlier this year. I did it on street tires. I found 2nd gear very usable with no problems getting the rear out when needed. My biggest issue was understeer, but is sounds like you know that and have plans that make a lot of sense to address the problem.

Best of luck.