[DCTepper]

I am looking to participate in my first SCCA autocross and want to make sure I am classed appropriately. My car is an e90 335i with JB4, BMS dual cone intake, and Hawk HPS brake pads, all else stock. I'm not so worried about the intake or brake pads, as both can be modified in Stock class, but am confused by the rules surrounding the altercation of boost levels (JB4). Below is an excerpt from the SCCA rules of the Street Prepared category

14.1 Authorized Modifications

D. Alternate computer control modules may be used whenever an equivalent change to the conventional system is allowed. For example, alternate computer module control of ignition settings or fuel injection is allowed. Direct turbocharger boost control by alternate computer control is not, since there is no equivalent mechanical allowance.

Source: http://www.moutons.org/sccasolo/Rules/sp.html

Forgive my ignorance, but this seems a bit cryptic, can run higher than stock boost or not? Overall, what class should I be in?

Thanks in advance for your help!!

[TSM330i]

I'm thinking that you would NOT be able to run any change in boost since there is no way for the SCCA to determine how much of an advantage you'll gain from it. Modifying boost on a turbo charged engine will give a much greater advantage than someone who modifies the ignition or fuel curves on an NA engine.

Besides, for an autocross, and your first for that matter, you really won't need the JB4 anyway. All you're going to do is cook your inside tire trying to come off turns anyway. You should be more worried with how you're going to actually get down the power with an open diff even with stock power.

Just take the JB4 off to be safe and talk to people once you're there. Run your first event and then assess where you need improvements.
I'm guessing power will not be one of them.

[DCTepper]

Sorry, I didn't explain myself very well, I've been competing for years, this is just my first SCCA event with this car. I did consider running the stock map and enter in B Stock, but thought it would be more interesting to see how she stacks up against others while at her full potential.

So, running higher than stock boost, what class should I be in? If not Street Prepared, Street Modified?

[vwong]

Originally Posted by DCTepper

I am looking to participate in my first SCCA autocross and want to make sure I am classed appropriately. My car is an e90 335i with JB4, BMS dual cone intake, and Hawk HPS brake pads, all else stock. I'm not so worried about the intake or brake pads, as both can be modified in Stock class, but am confused by the rules surrounding the altercation of boost levels (JB4). Below is an excerpt from the SCCA rules of the Street Prepared category

You may want to check the rules again. Under Stock class rules, only the air filter element can be changed. The path for the air must remained factory, that includes the air box and tubing which the BMS dual cone intake removed and replaced.

Originally Posted by DCTepper

Sorry, I didn't explain myself very well, I've been competing for years, this is just my first SCCA event with this car. I did consider running the stock map and enter in B Stock, but thought it would be more interesting to see how she stacks up against others while at her full potential.

You'll have to check the rules again. E9x 335i is classed in D Stock. Although you can run it in B Stock if you put the factory air box back in and run the stock map, but you'll probably get killed by the B Stock S2000.

If you want to run the car the way it is now, it'll be in Street Mod unfortunately.

Here are your scenarios:
- D Stock, if you put the factory air box and tubing back, and run the stock map
- STU, if you keep the BMS dual cone intake, and run the stock map
- SM, if you want to run the way it is now

[DallasBoosted]

If its your first Autox, its not going to matter what class you're in, just go drive and have fun. Your air filter and JB4 won't make a bit of difference regardless so just compare your times to the other D stock guys and see where you're at.

Have fun

[DCTepper]

Originally Posted by vwong

You'll have to check the rules again. E9x 335i is classed in D Stock. Although you can run it in B Stock if you put the factory air box back in and run the stock map, but you'll probably get killed by the B Stock S2000.

If you want to run the car the way it is now, it'll be in Street Mod unfortunately.

Here are your scenarios:
- D Stock, if you put the factory air box and tubing back, and run the stock map
- STU, if you keep the BMS dual cone intake, and run the stock map
- SM, if you want to run the way it is now

You're right, I mispoke, D Stock.

Thank you for laying out the scenarios, this is exactly what I needed. Thank you!

[TSM330i]

Originally Posted by DCTepper

Sorry, I didn't explain myself very well, I've been competing for years, this is just my first SCCA event with this car. I did consider running the stock map and enter in B Stock, but thought it would be more interesting to see how she stacks up against others while at her full potential.

So, running higher than stock boost, what class should I be in? If not Street Prepared, Street Modified?

Got it

Again, you're going to toast your inside tire on tight turns. Just run the stock map and try it out first. Once you see how little the tune will be doing at these reduced speeds and the lack of traction you won't miss the power.