E36 328i SCCA TT Sport Class Setup

[HandsomeMike]

Me again. Long time reader, infrequent poster...

97 328i Sport

I started track days this year. Just did my third of the year on Saturday. All at NCM. I plan to compete in the TT Nationals in June in Sport 4. For those of you not familiar with the rules, Sport class is the lowest as far as mods. Long story short, my lap times are getting faster, and my top end is getting higher thanks to carrying speed better onto the straights, but when I watch videos of other cars in S4 at NCM, they are still going about 6-8 mph faster than me on the longest straight.

This is my first year owning an E36, and from all the extensive reading I've done, it appears that a CAI alone is worthless and a cat-back alone is worthless. Powerwise, I am only allowed to install a CAI (anything up to the throttle body), flash the ECU and replace the cat-back exhaust. I know there are no major power gains to be had even if I did all three.

Question - I would like better throttle response to hopefully get me up to speed faster out of corners and hopefully gain those 6-8 mph I'm lacking. I know that continuing to improve my balance and carrying more speed through the corners is still priority #1, but would any of or all of these options help me keep that exit speed and help me on top end? I've read that the Shark Injector tune helps to take better advantage of 93 octane gas, better throttle response, etc. Is it worth it? Would you do the SI with the intake? SI and cat-back? All three?

Like I said, I am still new to these cars. Any help is appreciated!

Mike

[MINIz guy]

My 328i is a T4 car but it should apply.

Yes, a CAI won't add much. I still run a stock air box. An exhaust will lose you weight, but no power would be had as I believe the power gains are from a Bimmeworld y-pipe and a high flow cat. I run an RKTune and the mid-range feels beefier, but I've never dyno'd my car.

Your speed could be gained by running a smaller diameter tire. Our 2.93 rear diff makes for some looong gearing. A smaller diameter tire will do something similar to a shorter rear diff ratio.

[HandsomeMike]

Smaller than the stock 16"?

[MINIz guy]

Smaller than the stock 16"?

Yea, smaller diameter tire than the stock 225/50/16 (diameter ~24.9"). Did a quick check and I'd do a BFG Rival S 1.5 on a no-camber E36. They have a 225/45/15 available (23" diameter) and Tire Rack has Sparco FF-1 wheels in either 15x8 ET20 or 15x9 ET30 sizes. Might take some massaging of the fenders, or somebody to machine the offset down (maybe too much effort at this point), but they are options. Maybe with some luck a 225 on a 9" wheel will be enough stretch that it clears with only a roll. I believe 225/45/15 Rivals on a 15x9 is a common Miata fitment, so not a crazy stretch.

Plugging the tire and gearing into a calculator, 2nd is 60 MPH, 3rd is 91 MPH and 4th is 122 MPH with the stock 6500 RPM redline. Gearing is plenty usable on track and definitely more favorable than stock gearing.

[jonb94118]

6-8 mph towards end of straight, over the entire straight, or?

The classes where I have raced (GTS, Super Touring) have always been power to weight, so I have spent lots of time on dynos and can tell you that you'd be surprised by what a decent intake and exhaust will do all else equal. The Bimmerworld Race intake works very well. Some of the cone based CAI's I would say are pretty worthless. taking weight out of the car, and getting it to WOT for a larger percentage of the lap, is where you will make the most gains.

[HandsomeMike]

6-8 by the end of the straight. I hit 104 when I had to lift and other cars in class are hitting upwards of 112 or so. I looked at all the eligible cars last night in the rules and at which cars are actually racing in the nationals and Googled their HP ratings and I'm at a good 20hp deficit to most cars. More on others. I don't know how to compensate for that without getting into the engine.

I know I still have a lot of work to do on myself but even once I get pretty good at NCM, I still think the car will fall short. My first time out this year, my best lap was a 2:58, second event was 2:52 and last weekend was 2:47. I need to get to 2:32. Tall order!!! I know I can get into the high 2:30's but finding 15 seconds will be incredibly hard.

[matthugie]

My question would be what is your suspension setup? Sport allows lowering springs, aftermarket shocks, and replacing the front sway bar. If you haven't already done those that's where I would start.

[emoore924]

Brakes grasshopper, better brakes.

[HandsomeMike]

H&R sport springs with matched shocks. I believe they use Bilstein. Eibach front bar. Current pads are Hawk HP+ that are about to go in the trash when I put street pads back in for the off-season. The HP’s are garbage. I’m trying DTC60’s next. I do think that if I know I have more brake bite and higher pedal that I’d be confident to carry more speed and brake touch later.

[HandsomeMike]

Is there anyway to get this body lean under control? It's controlled by spring rate and roll bars, correct?untitled-July 18 2020-2071.jpg

[MINIz guy]

It's controlled by spring rate and roll bars, correct?

Yes.

If you want faster acceleration, just change the rolling diameter of your tires.

[emoore924]

...or your differental

[HandsomeMike]

emoore, its against the rules.

[dominator293]

May or may not be relevant, but a few things from my experience.
1. Are you allowed to shed weight from the interior? If so, loosing weight increases speed.
2. Upgrading the exhaust will do the above, loose weight and potentially add a little more power (a few hp).
3. Same goes for a CAI, potentially less weight than the stock air box and potentially a little more power (1-3~hp)
4. Certainly worth getting a ECU tune. I dyno'd my 325i before and after an ECU tune provided by a company here in Aus. 119rwkw before, 129rwkw afterwards (so around 13hp gain).
5. Muck around with tyre sizes like MINIz said, that may gain you some additional acceleration too.
6. Suspension is a big thing, faster you go around the corners, the more exit speed you get so you'll achieve those higher top speeds by the end of the straight.

[bimmerboy318]

Hey Mike, keep going, you’ll get there. The first time I broke 2:30 I thought that was it. Now I’m running 2:25 and better drivers than me are saying the car can break 2:20. Practice, practice, practice! Treat the e36 as a momentum car. I run a 2:32 in my Miata and similarly setup cars are running 2:27 at Nationals. So between both platforms my driving skills are 5sec off the pace at NCM. I need more track time!... lol.

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No!... learn how to not brake. Learn how to get on the brakes and release. It took a while to click for me... but the best advice I was given to gain time was when to release the brakes!

[emoore924]

Ahhh, rules. Dag nabbit.

[dominator293]

Hey Mike, keep going, you’ll get there. The first time I broke 2:30 I thought that was it. Now I’m running 2:25 and better drivers than me are saying the car can break 2:20. Practice, practice, practice! Treat the e36 as a momentum car. I run a 2:32 in my Miata and similarly setup cars are running 2:27 at Nationals. So between both platforms my driving skills are 5sec off the pace at NCM. I need more track time!... lol.

- - - Updated - - -

No!... learn how to not brake. Learn how to get on the brakes and release. It took a while to click for me... but the best advice I was given to gain time was when to release the brakes!

I'd love to know your trick and techniques around braking. I'm an average driver in a car with a lot of potential, so I need all the help I can get!

[HandsomeMike]

Just saw these replies. Haven’t been on for a while!

Bimmerboy, I’ve been watching a lot of video of me and Andy Pilgrim driving NCM. I know I’m over braking and carrying too much speed into corners. I understeer a lot which is scrubbing speed. I need to get better at braking like you said and keep telling myself slow is fast. This is my first year of track driving and I’m driving like its autox. All brake or all throttle. I will seriously be hitting you up to ride with me when 10/10th’s is at the track this coming year. The good news is that of the three days I did this year, I went from 2:57 to 2:52 to 2:47. Seat time and finding balance is key, you’re right about that!