I did a search but didn't successfully find a reference thread that detailed all of the things you can and can't modify for a ST-legal tune. Especially for a FI car.
All I've seen so far is that you cannot change the boost maps. Everything else is fair game even if it indirectly affects boost.
I'm a newbie at tuning so I don't know all of the parameters that are available. So a list of parameters we can and cannot change would be helpful.
This is all I have so far:
Can:
Timing,
Fuel,
Rev Limits
Cannot:
Boost Maps
I'm having the same questions... I'd like to use the m54 intake manifold on my m52 but not really sure if that would put me in the same class as some much better built/dedicated cars.
e46potenza wrote:
I'm having the same questions... I'd like to use the m54 intake manifold on my m52 but not really sure if that would put me in the same class as some much better built/dedicated cars.
Definitely, it takes a while getting up to speed on all of the different regulations.
Regarding the intake manifold, I believe you cannot replace the stock intake manifold. Per 14.10.B: "The air intake system up to, but not including, the engine inlet may be modified or replaced. The engine inlet is the throttle body, carburetor, compressor inlet, or intake manifold, whichever comes first."
Well dang. Looks like I'll just have to stay a little more stock-ish. Or just stick to HPDE's lol
Huge exhaust with stock wastegate and take advantage of boost creep?
(Not that I'd want to do that on my own car)
Haha thanks. I'm mostly focused on the ECU tune part of the ST-rules in this thread. The rule book isn't super clear except for... no changes to boost maps... but it's ok if you change other parameters.
My main question with the manifold would be... since it's technically a stock bmw part from that year, would it be considered not stock? Or have they closed that loophole and I'm just new lol. Seems like on an FI car it would be hard not to alter boost at least a little with supporting mods. When I replaced intake & exhaust along with a tune up on my z31 (years ago), I went up almost 2# of boost.
Hal
SuperDork
8/19/14 2:16 p.m.
The rule with SCCA is: If it doesn't say you can then you can't.
Hal wrote:
The rule with SCCA is: If it doesn't say you can then you can't.
Well I suppose that settles it then lol
nilfinite wrote:
Haha thanks. I'm mostly focused on the ECU tune part of the ST-rules in this thread. The rule book isn't super clear except for... no changes to boost maps... but it's ok if you change other parameters.
That's my point, as mentioned, typically opening up the intake and exhaust nets more boost. You can then tune the fuel/timing around that increase boost.
z31maniac wrote:
nilfinite wrote:
Haha thanks. I'm mostly focused on the ECU tune part of the ST-rules in this thread. The rule book isn't super clear except for... no changes to boost maps... but it's ok if you change other parameters.
That's my point, as mentioned, typically opening up the intake and exhaust nets more boost. You can then tune the fuel/timing around that increase boost.
Ahh ok makes sense. I guess I was wondering if there were other parameters that people usually tweak when they tune their car other than fuel and timing.
The rulebook says that you can change the tune of the ECU or use a piggyback unit.
In reply to e46potenza: Street Prepared cars can't remove the interior so you don't have to get too crazy with mods,depending on the local talent, but you do need slicks to win (probably).
Yea... some of the cars I've seen on the local auto-x galleries look pretty hardcore to say the least. Thinking that my mostly bolt-on 328i will be in those classes because of wheel width is a bit discouraging lol
nilfinite wrote:
z31maniac wrote:
nilfinite wrote:
Haha thanks. I'm mostly focused on the ECU tune part of the ST-rules in this thread. The rule book isn't super clear except for... no changes to boost maps... but it's ok if you change other parameters.
That's my point, as mentioned, typically opening up the intake and exhaust nets more boost. You can then tune the fuel/timing around that increase boost.
Ahh ok makes sense. I guess I was wondering if there were other parameters that people usually tweak when they tune their car other than fuel and timing.
If you exclude boost, there isn't really much else you can tune for except for variable cams and the like.
Mr_Clutch42 wrote:
The rulebook says that you can change the tune of the ECU or use a piggyback unit.
On a naturally aspirated, pre-OBD2 car that does not have traction control built into the ECU, it is also legal to completely gut a stock ECU case and stick a standalone ECU in there provided you make no modifications to the case itself and do not add additional sensors. At least, that's the way that "Reprogrammed ECU/PCM (via hardware and/or software) may be used in the standard housing" has been interpreted, since they failed to set limits on how much hardware could be used for the reprogramming.
The piggyback allowance is nearly as wide-open provided you can make a suitable adapter harness. One could, theoretically, make a wye harness that leaves the stock ECU's power, ground, and OBD2 port connections, and plug a Bosch Motorsports racing ECU into the other side.
Things that are unequivocally not allowed:
- Changing boost control settings in the ECU on a car running forced induction
- Changes to traction control
- Breaking OBD2 communication functionality
- Using non-original sensors for engine management
In reply to MadScientistMatt:
I'm sure the SCCA has a group of racers that talk about the details of how and what certain language forces competitors to change on their cars, especially when you are changing old tech equipment compared to new tech.
