What class do minor mods put you in for Autocross

[Jaynen]

So I was just curious if anyone knows. I kind of wanted to get back into Auto-X which I had only briefly done before. I also plan on buying a TDI shortly. But I really like the sound of going to some Sprint 520 injectors and an RC 2 tune for normal use. Not that I plan to hot rod the car but it seems like a nice and driveable level of tune. How does this impact what class you run in auto-X not that I want to be competitive but if it was not for wanting to do those mods I would largely want to leave the vehicle more in line with stock class.

I guess I could run HS but I have the feeling the base tune may be a lot less enjoyable?

(I wouldnt consider a chip and injectors minor mods on a gas car but they feel so common in regards to TDI's)

 

[66Stang]

It will bump you to a prepared class. Which would be good, as you will want a stiffer rear sway bar to autocross a TDI.

Someone correct me if I am wrong, but TDI's tend to understeer. A larger rear sway bar will make the car more neutral and fun to drive, both on the street and during an autocross.

I'm thinking the same thing for my next car, as I think the tourque of a TDI would be great during an autocross.

Chris

 

[Jaynen]

Yeah you won't be competitive at all in a prepared class I imagine but my goals are to have fun and driver skill improvement.

 

[Ian F]

I was running my TDI for much of this season in HS (running old street tires). Not competitive, but I managed to get a couple of trophies in Novice class. To this end, I did some research on what mods I could do.

To stay in HS, I could do the following:

Koni Yellows
R-Comps (225/50-15) on OEM wheels (since I've not been able to find any aftermarket 15" wheel that matches the OE dimensions)
5mm spacers on the front wheels (figuring a little extra track up front can't hurt)
cat-back
matched & optimized stock injectors.

...and that's about it... that tire size will drop the gearing a bit and (hopefully) make the acceleration a bit quicker (something I had problems with). The downside being the need to shift to 3rd on most courses when gassers can simply leave their cars in 2nd. Since I was usually bumping the rev-limiter in 2nd on most courses anyway and occasionally shifting to 3rd, I figured this didn't really matter.

Then I looked at possibly doing something to increase HP... and here, TDI's have an advantage most cars don't have - the ability to easily adjust fueling to seriously make more power (a PowerBox). Since this doesn't affect boost levels, it keeps the car is ST class where there are more suspension upgrades allowed, and it has a ghost of a chance of being competitive, depending on how many 89 Civics built to ST specs compete in your region. Since I have a past ST National Champion Civic in my region, I decided this wasn't worth it. The problem the MkIV has in ST is weight vs' the 225 tire width limit (at least we have more tire and wheels options here). Against a 2000 lb Civic, the 3000+ lb MkIV simply doesn't have a chance, no matter what you (can legally) do to the engine and suspension.

In my case, I have a 3rd option: run a different car. A 2007 MINI Cooper convertible in HS. I did this for the event this past w/e. While I'm still not as comfortable in the car as I am in the TDI, it has better tires (new Direzza Star Specs vs. worn out SP8000's), better acceleration and obviously better handling. While I finished about the same in Novice class, my times in HS were considerably more competetive.

Could you build a Mk IV for a Prepared class and have it be competitive... possibly... although due to the mods required, it would basically end up being a dedicated race car with poor street characteristics.

So, in the end, as much as I enjoyed the novelty of running a TDI wagon in auto-x, and I definitely wasn't the slowest car out there (my g/f was pissed when she her times in her modded '03 MCS rarely beat mine), I think the TDI is now retired from auto-x...

 

[Jaynen]

But if you only have one car I say take it to the track/auto-x

I love open track days as well so maybe I wouldnt care if I can go do a track day getting 30+mpg

 

[Lug_Nut]

It will bump you to a prepared class. Which would be good, as you will want a stiffer rear sway bar to autocross a TDI.

Someone correct me if I am wrong, but TDI's tend to understeer. A larger rear sway bar will make the car more neutral and fun to drive, both on the street and during an autocross.

The stiffer roll resistance at the rear (greater tendency to oversteer, or less tendency to understeer) can be approximated by making the front have less roll resistance in comparison. Removal of the front anti-roll bar will accomplish much of the same results as adding a rear anti-roll bar, without the class bump.
This will work for a dedicated 'stock' autocross car, but the wallowing on the weekdays won't be enjoyable. Stiffer springs up front will compensate for the roll but might bump the car a class. Maximum firmness on compression dampers up front will slow that stock spring's roll rate to a degree that the lean in an auto-x turn and most daily drives (except for long sweeping on-ramps and such) can't progress far at all before the turn ends and the leaning ceases.

 

[Stealth TDI]

BTW, altered boost bumps the car to STREET Prepared... not PREPARED. Big difference. Otherwise, it's all fun! Keep in mind that "HS" is where the slower cars are. If you want the car to be more powerful, then you have to be ready to move up. Good Luck!

 

[Ian F]

Removal of the front anti-roll bar will accomplish much of the same results as adding a rear anti-roll bar, without the class bump.
This will work for a dedicated 'stock' autocross car, but the wallowing on the weekdays won't be enjoyable. Stiffer springs up front will compensate for the roll but might bump the car a class.

One of the Mk IV's I run with had that when he first started (full Shine kit w/ FSB removed) and the car did not handle well - always on the edge between understeer and spinning and not balanced very well. Reinstalling a FSB knocked about 3 seconds off his times. He runs in ST ('05 1.8T).

Yes... "prepared" and "street prepared" are quite different classes... but of little matter to a TDI... since one won't be competitive in either. Most of the SP cars that run in my region (at least the ones that win), are barely street cars.

IMHO, staying in HS with a TDI with decent street tires isn't a bad idea if you're just starting out. You end up having to concentrate on driving correctly and being smooth, since you don't have a lot of power or suspension grip to make up for mistakes. Plus, by competing in a class where few mods are allowed, it makes that debate over "should I spend the $$$ on this mod?" a lot easier... I really wanted to try preping the wagon for HS, but it would have been more of a gamble (~$1600 for Yellows and R-comps) on competitiveness. I know the MINI can be competitive in HS, and since I'm lucky enough to have that option... Although I admit it would have been fun to try with the TDI...