It took long enough, but the ZHP finally hit the track for its first shakedown. There was definitely a bit of prep work involved to get it here, but nothing close to what it took to make my e30 track worthy (…it’s as if car design has improved with time). Here is the story of getting my 2003 ZHP to Thunderhill and my initial assessment of a “modern” 3 Series BMW put through its paces.
Just a Few More Reliability Mods
Oil Pump Shaft: Previously I had the rear subframe reinforced on the e46, however the battle wasn’t over yet. Since the 3.0-liter M54 has some nasty harmonics when you rev it closer to it’s redline, the oil pump nut can back off and potentially shear, causing the oil pump gear to leave the chat and bye bye engine! While the ZHP cars have the oil pump nut thread-locked from the factory, the other issue is the oil pump chain slaps around at high RPMs, which can still lead to the oil pump shaft shearing.
After frying my brain with forum thread arguments, the problem seems to lie in the fact the oil pump shaft spline location is thinner diameter than the rest of the shaft, making that the weak point. Fortunately there are many ways to fix this with a beefed-up aftermarket part, but get ready to spend a pretty penny on a ready to install oil pump. Not wanting to spend 700+ dollars on this, I opted for the Achilles Motorsport keyed shaft and gear which is about half the cost. The catch? You have to press it onto your factory oil pump shaft gear. So you will need a set of digital calipers to measure the factory gear placement on the shaft, then use the press to install and match the upgraded pump shaft to the same location.
I found it easiest to buy a spare oil pump and have the upgraded shaft installed onto a spare gear so I could simply remove and replace the oil pump once the pan was off…which leads to the next mod–oil pan baffle.
Oil Pan Baffle: Just like the other 6 cylinder BMWs, the slanted engine placement means oil can creep up the side of the block during extended left hand corners under high loads. The fix? A trap door baffle to keep oil at the pickup where it’s needed to prevent a major pressure drop. Having had good luck before with AAF on my e30 baffle, I purchased their e46 version for the ZHP.
Unfortunately the baffle install requires welding to the aluminum oil pan, so if you’re not savvy in that department (I sure am not!), it’s best to have someone do it for you. Like the oil pump shaft upgrade, I found a good used M54 e46 pan, cleaned it, then had someone weld in the trap door baffle so I could simply swap parts to minimize downtime. Naturally you’ll need to do the pan gasket during this time, but let’s face it…your e46 was probably leaking and desperately needed it replaced anyways.
Some Fun Suspension Goodies
Fixed Camber Plates: Just like my e30, I knew the front tires would get chewed up if I didn’t figure out a way to add some front camber. Since the car is still on stock suspension aside from a better set of Koni shocks, I didn’t want to go overboard with race style camber plates.
The cheap/free way to do this is to punch out the stock strut mount alignment pin which will let you move the mount more inboard courtesy of the factory slotted strut towers. This will supposedly give you an extra .5 degree of camber adjustment but may not be enough depending on driving style. In my case I went with a fixed mount camber plate from Turner.
The Turner plates sit on top of the factory rubber strut mount, so no NVH increase, but they bring negative camber into the -2.5 degree range for better tire wear and handling on track without being too aggressive for street use. Since the rear is already in the -2.0 degree range, this helps dial out the understeer from the factory alignment. Since the fixed camber plates bolt to the existing strut mount, they slightly raise the front ride height, but I wouldn’t have noticed if nobody told me.
200TW Tires & Light Wheels: The biggest handling improvement you can do to most cars is a stick set of tires. For a track day, 200TW is the preferred weapon of choice these days for grip while still being roadworthy for the drive home. Previously I had complained how heavy the stock ZHP wheels are at nearly 30lbs, so this was the perfect opportunity to shed some weight as well.
I went to Tire Rack and bought a set of Kosei K1 wheels in 17×8.5, which are about as cheap as you can buy new at ~$200 a pop. Since I was downsizing to a 17-inch wheel, I was able to get some blowout sale Continental track tires in 245/40R17. So not only was I getting stickier tires, but the wheels weigh only 17 lbs. and have better ride quality due to the larger sidewall. Being a square setup, I am now able to rotate tires and have gained more front grip over the staggered factory setup.
Track Pads: It probably goes without saying, but I installed a set of track brake pads and flushed the fluid, however you may be able to get away with some cheaper sporty street pads depending on the track. Knowing the ZHP is a bit of a porker at 3300lbs before the bipedal porker enters the equation, I figured the brakes would certainly be putting in some work. In my case I used PFC08 pads because they were available to me, but plenty of other options exist that won’t break the bank. Also don’t forget to make sure your fluid is fresh. I used ATE 200 in my case since it’s affordable and can handle most HPDE braking applications.
ZHP Gets a Workout
With all the please-don’t-blow-up-on-me mods installed, it was off to Thunderhill in Willows, CA. I was lucky enough to be invited to a private track day at the 5-mile course, so it was essentially a full day of driving with minimal downtime. I packed the car and headed up the night before so both the car and myself would be well rested for the ensuing day of poor fuel economy and melted rubber.
I had been to Thunderhill previously, but only ran the 3-mile East course, so the combined 5-mile configuration meant I could experience the more technical West course as well, and it would provide most scenarios to give the ZHP a solid shakedown. Initially I left the traction control on since it was a new car for me, but in short order it became too intrusive and I shut it off completely.
For a stock suspension, the ZHP did not exhibit nearly the body roll I was expecting. Perhaps the spring rates are much stiffer than I give the car credit for, but aside from managing the body roll between transitions, I was surprised how composed the car was throughout the day. It had no problem on the higher g-force Turn 2 bowl section, nor did it break a sweat at 85-90mph clipping the apex of Turn 8.
My friend Will was able to time me and I was able to clock a 3:46 with the “cyclone” paired with the bypass on the West course. At least next time I have a potential benchmark to compare to should I run the same layout.
I am also glad I didn’t lower the car because it allowed the suspension to do its job without running out of travel–go figure. On a street car with softer stock springs, every bit of travel counts. Another surprising bit was the open differential didn’t seem to be an issue for the initial outing with the e46, but there aren’t too many low speed tight corners at Thunderhill so perhaps that could be the reason why I wasn’t trying to find an LSD solution immediately. Good news for me because a non-M limited slip differential costs an arm and a leg for an e46.
Time to Complain
It wouldn’t be a complete review without being able to complain, right? Overall the e46 is a very capable car out of the box, especially coming from the world of semi-trailing arms which were invented sometime between the first cave paintings and Noah’s Arc. That’s not to say the ZHP…even with its “cams”…doesn’t have its shortcomings.
Shorter Final Drive: Most immediatley, the gearing is too tall to have serious fun in a 330i. While the 3.07 ZHP final drive is sportier than the 2.93 of a normal e46 330 manual car, the spread between gears wasn’t “rowdy” enough for a higher speed track like Thunderhill. On the main straight at 110 MPH, the car only needed 4th gear. More importantly however, the holeshot out of 2nd gear is too long and too much of a drop in revs when shifting into 3rd.
While I could have tried squeezing every rev out of the M54, it loses steam past 6k. Revving it any higher is just for noise or attempting to win at an autocross before an ND Miata sweeps the house. To fix this, I have a 3.38 differential out of an automatic 330i that I will swap in at some point. I feel this will give the car the pep it needs while still retaining 6th gear cruising manners on the highway, but also shorten the gear spread for my local tracks to keep my shifting in the 3rd, 4th, & 5th range and eliminate the typically annoying 2nd gear downshift.
Shifting Ergonomics: Everyone compliments the ZHP weighted shift knob, but for my string bean arms it sits too low. I plan to swap the knob out for the normal height “Anatomic” knob, but also plan to change the shift lever itself. Not so much to gain a short shifter (shifts are fairly short as-is), but rather to get rid of the upright shift lever in favor of one that is tilted slightly rearward like many of the older BMW models. I have a spare e60 545 lever that I think will accomplish this. This way the shift falls to hand easier for shifting.
Recaro Sportster – Good but not Great: Previously I had installed a Recaro Sportster driver seat in my car because the stock leather sport seats were unusually uncomfortable. The new seat certainly helped ease the back pain and provide a bolstered upper body section, but on track I was still bracing my lower body against the door and center console.
Ultimately if I continue down this route I’ll need a proper bucket seat, but I was surprised that in just a single event I had exceeded the bolstering abilities of the Sportster in an otherwise stock vehicle–which isn’t even a proper sports car at that! I guess this is slightly good news then as it means I’m picking up the pace with my driving.
Turn Up the Volume–Intake and/or Exhaust: Under most circumstances I do not want a noisy car. They’re typically irritating and drone at the most inconvenient RPMs. The e46 however felt that its predecessor the e36 was somehow too noisy, so even the performance oriented ZHP is excessively quiet. For daily driving this isn’t a problem, but on track it’s hard to discern what the engine is doing without blatantly monitoring the tachometer.
There are two trains of thought to solve this. The obvious solution is to install an aftermarket exhaust which will simply increase the volume whether requested or not. The alternative approach is to install an aftermarket intake, which will create more induction noise under acceleration, but the exhaust volume will remain essentially the same. This is likely the route I’ll go, but this is still to be determined.
Low Buck Track Capable Daily
There you have it folks, with a few mods, even a 20+ year old 3 Series can turn hot laps at your local track. Knowing what I know now, I would say that a regular 330i sport package car or even a 325i or 328i e46 can be just as much fun and can be had for even less than a ZHP. As long as the engine is reliable, it’s quite impressive how capable these cars still are with essentially a set of shocks and sticky tires (this also applies to the e36 as well).
The nice thing about these cars is you don’t need to throw the kitchen sink at them immediately to get them track worthy. Most of these jobs can be tackled on a weekend, or even a shop shouldn’t charge too much for labor if you have someone else do the work. The only job that is going to be costly from a labor perspective is going to be the rear subframe reinforcement, but there are some bolt-in braces that arguably perform the same function at the expense of some trunk space. This is probably what I should have done first, but oh well too late. Now to come up with an excuse to justify all of this to myself. How about “skill development” and “networking events”. Oops, this isn’t LinkedIn.
-JC
