just another sunroof-less ZHP autocross STX build and events chronicle

[fw_fw]

The guys at work remembered your car.....said it was a great looking ZHP!!

[GoGators]

while the car is down for the M3 header modified for ZHP project, I went ahead and installed the M3 fuel baffle in the tank. very very easy, though I would recommend doing with a lower fuel level than I had at the time (1/2 tank)... the part was ~$20 on ECS. I figure it will allow me to autox with 1/4 of fuel, vice the normal 1/2 tank. so a net loss of weight of ~3 or 4 gallons or ~20lbs. for $20, that's cheap weight loss!

[GoGators]

link to my ongoing conversion of an M3 header for use on my ZHP:

http://www.zhpmafia.com/forums/showt...ds-for-ZHP-M54

[GoGators]

final result of my latest effort (installing OEM M3 headers with Vibrant muffler).

next autox is this weekend, so hope to get a feel if I gained any top end from the tubular M3 headers.

[GoGators]

Video of my quickest pass from sunday. my best was still ~1.4 seconds behind the STX winner (a 240), with 2 BRZs, in between he and myself. placed 22nd of 61 overall, which considered my aged tires, felt pretty good... at the end of this video is a low-light, came into the turnaround too hot, then got back into the gas a bit much, no lift!

https://youtu.be/BFbgld7vs5Q

still feel like the car should turn in better. here is a short clip, when I turn into the "Chicago box" I am full brake and turn left, pretty smoothly, but the car continues straight, straight thru the cone.. I feel like what is holding me up is the amount of speed I have to shed to get the car to turn in...

https://youtu.be/0Nqkk2fMlNo

[GoGators]

I ended up 3rd of 10 in class STX (ahead of 5 of the 6 AE86/FRs/BRZs), 19th of 50+ overall. In the rear I am still running ~2yr old Rivals, 265-series, they are shot. Needless to say I had a loose condition all day, even at ~30 psi and full soft on the rear sway bar and rear shocks.

First clip is my backwards slide through the finish lights... Second clip is my second pass, I had a first-time autocrosser along for a ride. Nice lady, probably mid-50s. She had brought her fancy Porsche Macan out to run and wanted to see the course before taking to her runs. I think she was a bit surprised at how wild of a ride it can be in what outwardly appears to a plain sedan. Ended up washing out coming through the airfield cross-over heading into the turn-around. You cant really tell how sideways the car is, but you can see where the steering wheel is and that the car's direction isn't changing bc the rear is tracking, until it goes completely..

[GoGators]

https://youtu.be/f6m_LFOTKxY

Saturday was our annual night event. This year we did a split / combined event, running 3 runs in the afternoon and 3 runs at night. Your best day run was added to your best night run to determine results. It was a nice event.

I put the full set of used (~4 yr old) 255-series star specs on. Time hasn't been friendly to them. Even at ~28psi they had very little grip. Was fun, but not fast. I placed 19th of 47 overall and 5th in STX.

Starting to look at new tires. didn't get any this year bc the hot tire is the 71R, which for my 18"s would run ~$1200 for a set. However, some locals are running the new Nexen 200TW tire and think they are comparable to the 71Rs. But, they are only ~$700 set. Also would still like to get a set of lite weight wheels 17x9s, the NExens are only ~$500 a set on 17". super cheap!

[M0nk3y]

https://youtu.be/f6m_LFOTKxY

Saturday was our annual night event. This year we did a split / combined event, running 3 runs in the afternoon and 3 runs at night. Your best day run was added to your best night run to determine results. It was a nice event.

I put the full set of used (~4 yr old) 255-series star specs on. Time hasn't been friendly to them. Even at ~28psi they had very little grip. Was fun, but not fast. I placed 19th of 47 overall and 5th in STX.

Starting to look at new tires. didn't get any this year bc the hot tire is the 71R, which for my 18"s would run ~$1200 for a set. However, some locals are running the new Nexen 200TW tire and think they are comparable to the 71Rs. But, they are only ~$700 set. Also would still like to get a set of lite weight wheels 17x9s, the NExens are only ~$500 a set on 17". super cheap!

Just IMO - Nexen tires are no where near the performance level of 71Rs.

[murph]

Wish I'd seen this earlier, I'm glad to see someone is still carrying the E46 torch in STX!

It was a few years ago now, but I did a pretty complete build on my ZHP, check it out here:

http://www.bimmerforums.com/forum/sh...-STX-330-Build

Some comments I have on your build:

1. With the wavetrac diff, your spring needs may be different than others with purely clutch diffs, because it will put more than 50% of the power to the outside rear wheel. I experimented for one weekend with a gear-type diff and had to run much softer rear springs and yank the rear bar. That may be similar to your experience of it feeling really loose.
2. Make sure you're not getting into the bumpstops. You can measure that on the shocks by tying a zip tie to the shock shaft and seeing how far it's moved at the end of a run.
3. I have some bits you may be interested in for sale... I have some custom lightweight seat mounts I had made for the E46 that fit sparco sliders and work really well. I'll sell them cheap.
4. I tried the same thing with welding some M54 flanges on S54 headers, I'm glad to hear you had better luck! I'm sure that will be a better setup than the S52 headers to custom Y pipe and cat setup I ended up with. Others have modified the Bimmerbrakes M54 headers to add cats at the end with good results.
5. I would focus more on weight than power. The car has plenty of power, but it's a pig. GET RID OF THAT WEIGHT!
6. I would also heavily recommend some 9" wheels and the fender rolling needed to fit them, you need every bit of wheel width you can get.
7. With a little practice, rear spring changes are super easy and can be done in 5 minutes. Get a few different springs in 100 lb increments and try some things out during a testing event.
8. If you do get a tune, make sure they remap the throttle response to a fully linear map, that will help a ton with mid-corner throttle control. That's something I missed when I got my tune and I was kicking myself for years.

[GoGators]

Wish I'd seen this earlier, I'm glad to see someone is still carrying the E46 torch in STX!

It was a few years ago now, but I did a pretty complete build on my ZHP, check it out here:

http://www.bimmerforums.com/forum/sh...-STX-330-Build

Some comments I have on your build:

1. With the wavetrac diff, your spring needs may be different than others with purely clutch diffs, because it will put more than 50% of the power to the outside rear wheel. I experimented for one weekend with a gear-type diff and had to run much softer rear springs and yank the rear bar. That may be similar to your experience of it feeling really loose.
2. Make sure you're not getting into the bumpstops. You can measure that on the shocks by tying a zip tie to the shock shaft and seeing how far it's moved at the end of a run.
3. I have some bits you may be interested in for sale... I have some custom lightweight seat mounts I had made for the E46 that fit sparco sliders and work really well. I'll sell them cheap.
4. I tried the same thing with welding some M54 flanges on S54 headers, I'm glad to hear you had better luck! I'm sure that will be a better setup than the S52 headers to custom Y pipe and cat setup I ended up with. Others have modified the Bimmerbrakes M54 headers to add cats at the end with good results.
5. I would focus more on weight than power. The car has plenty of power, but it's a pig. GET RID OF THAT WEIGHT!
6. I would also heavily recommend some 9" wheels and the fender rolling needed to fit them, you need every bit of wheel width you can get.
7. With a little practice, rear spring changes are super easy and can be done in 5 minutes. Get a few different springs in 100 lb increments and try some things out during a testing event.
8. If you do get a tune, make sure they remap the throttle response to a fully linear map, that will help a ton with mid-corner throttle control. That's something I missed when I got my tune and I was kicking myself for years.

Appreciate your input, I hadn't seen your thread before, I will wade through to see if there are some details that might help my effort! just skipping to the last page it sounds like you had put an immense amount of time and $ into it! Did you recently list/relist it for sale? I thought I saw it one of the forums, maybe sandbox?

I agree weight is the killer at this point. short of putting race seats and LTW battery I don't see much room for improvement. I think I am probably as lite as an e46 can get at 3225 (3250 on scca scales with 1/2 tank of fuel, now with m3 baffle I run ~1/4 tank). I daily it too much and typically have two kids car seats in the back, so race seats aren't practical...

for the rest of this year I am gonna kill my already dead ~5yr old star specs. when I get new tires next year, I thnk that is when I should go after fine tuning the rear susp and verify I am not bouncing off the stops, which I surely may be... I might get a set of 17x9s so I can run less expensive rubber. though, I am hesitant to drop another grand in wheels bc I too am thinking about getting out of STX.... tbd...

So far, the headers, though extremely time consuming, are probably my 2nd favorite mod on the car (lsd being #1 (of course)).

thanks again, please check back and drop any input you have, I try to remember to upload run videos when I take them...