I’m about 8 years late starting this build thread but I’ve got a long way to go so why not start now. The car is a 1997 Boxster I started running in NASA Time Trials last year (TT5), while it may not look like a Grassroots car with its fancy BMW art car wrap let me assure you it is. I’ve owned the car for eight years, I bought it in my early twenties and daily drove it for years while it slowly went from bone stock to what it is today. It was an autocross car for years then became the car I learned to drive on the track with, and I now instruct and run TT with it. You can see the evolution below. I just got married and may have kids soon so I’m thinking this upcoming year is going to be last shot at making every event. Last year I was placing 3rd place in a field of 6, this year I want to win! But to do that I need to close a 3-4 second gap in the existing field and with three more cars being built for TT5 right now I have no idea how much more competitive next year will be. This thread will cover what I’m doing to prepare for next year and the results of the season.
First the evolution, all three pixels of it.
Here's the gap I need to close (at VIR), I'm the blue line and the TT leader is red. You can see where I'm loosing time. The big take a ways here are that my corner speed and braking points are good but I'm loosing speed at corner exit. I still have a little under steer that is contributing to this and I am also exiting at a bad spot in my power band which also isn't helping. My main competition in this class is S2000s.
Here's how I'm going to do it.
1) last year was my first year with aero, I have some tunning to do which should help me improve corner speed and place me in a better RPM on corner exit. I think the only way I can keep up with S2000s in the straights is to have a higher corner exit speed. To do this I really also need to add some oiling improvements (Accusump, baffles etc) I'm on the original 150,000 mile engine.
2) Stiffen up the car with a cage to improve off gator handling. The car has gotten very weak over the years of abuse. For example if you jack it up you can't open the doors. I'm loosing geometry in corners and especially over gators which I think is causing problems
3) Improve reliability. This is a grassroots car so its not exactly had the triple platinum maintenance treatment. I have a few things to address and some additional cooling and oiling improvements to make.
4) Tires, my slicks are a little old. I always buy take-offs. Time to upgrade.
5) Track data acquisition system improvements. Time to get more analytical. Ive been borrowing one so I need to get one dedicated to the car
And here's last years TT5 field. More cars are being built as we speak though so we'll see how next year's group looks.
As as I mentioned I need to make some aero improvements this winter last year I learned a lot. Instead of buying an actual aero package I built my own splitter and bought a cheap HUGE rear wing that was being run on a supercharged ZO6 autocross car, so ya way over kill here. To add the aero I need to add some ballast to stay legal which was as simple as a quick trip to Play it again. The next problem was the splitter was now blocking my GT3 brake ducts which grab air under the car. And with rules not allowing holes through the chassis and with radiators at each front corner my only option was to install NASA ducts in the headlights. Which hell ya it looks awesome!
Side note: it feels great to bolt a 35lb weight down next to a light weight battery you just paid $200 for. Also probably need to address that ratchet strap battery holder. Tech doesn’t love that.
Ok a lot going on here, hoods about to come off, splitter is dragging on the ground it’s not looking good. Clearly not a factory Porsche racing effort. The first thing I learned is that WOW splitters take a lot of weight! I was meat balled on my second lap for this situation and had to remove what was left of the splitter which left me with just a huge wing in the back and a completely unbalanced setup. It actually worked great though minus a little understeer. This winter I’ll have to make a new stronger splitter. Also of note You can see that I also almost lost my hood due to cheap autozone good pins coming loose. Thank god it was only one. Probably need to address this before March as well. Are you starting to get that Grassroots feel yet? If not just hold on.
The next thing I learned is that when aero comes loose its disastrous! On the second day I loaned the car to a buddy who immediately came in telling me I was insane for driving the car with the death wobble it had. I had no idea what he was talking about so I took it out and sure enough it felt like a trailer jacking knifing but only on one part of the track. It was so terrifying I slowed the car down and was then meat balled for the second time of the event…typical. Turns out one bolt had fallen out of one end plate and was flexing which was dumping the load off the wing. Lessons learned locktight.
84FSP
SuperDork
12/31/18 10:52 a.m.
Love the progression you've made with the car.
Can you just reinforce the splitter you have or add adjustable drop down supports to the nose of the splitter?
Ya I need to do something. I had it supported with cables so if I hit something (like my trailer) it would flex up. I think I’m going to keep this approach but add more cables.
Welcome to the forum and thanks for sharing with us. I have a 996, but 986's are getting too cheap to ignore in my area. I may be going down a road not so different from yours.
white_fly said:
Welcome to the forum and thanks for sharing with us. I have a 996, but 986's are getting too cheap to ignore in my area. I may be going down a road not so different from yours.
Ya they really are, I've seen them as cheap as $3K. They're great buys.
Which rollbar do you have on the car now? Will the stock top clear it? I like the wrap.
Adam
I've seen you at our events, glad to see you on here too! Aero is this magical thing that you have to re-learn how to drive with. Sounds like you are making good progress though.
A few questions and things to note -
- Has the car been corner-balanced, or do you just "make weight" - corner-balancing will help a bit in keeping it predictable and neutral
- Stock rear end or aftermarket? All of us with E36 M3s tend to upgrade to a more aggressive lockup with a built diff. It helps with acceleration on corner exit, and the shorter ratio adds acceleration while keeping you legal on power.
- Tires! Stop using take-offs. If you want to win, pay up homeboy. TT sessions are short enough that the Hoosier A7 may be a good choice, it'll come up to temp quickly and you aren't doing sprint races that would potentially see it fall off.
- If you like the photos that the track photographer takes of your car, he'd appreciate if you pay for them :-) I don't make all those announcements every weekend for nothing.
I ran TT for three years before moving to GTS2, managed to bring home some seasonal podium trophies in the now-dying TTD class at the time. The biggest thing I learned was that while "driver mod" can make up for some of the gap between you and the leader, it's really hard to make up that time on sub-standard equipment. I would corner balance ASAP, get new tires for March VIR, and explore options for the rear end if it's even necessary. The first two will absolutely help close that gap.
Brake_L8 said:
I've seen you at our events, glad to see you on here too! Aero is this magical thing that you have to re-learn how to drive with. Sounds like you are making good progress though.
A few questions and things to note -
- Has the car been corner-balanced, or do you just "make weight" - corner-balancing will help a bit in keeping it predictable and neutral
- Stock rear end or aftermarket? All of us with E36 M3s tend to upgrade to a more aggressive lockup with a built diff. It helps with acceleration on corner exit, and the shorter ratio adds acceleration while keeping you legal on power.
- Tires! Stop using take-offs. If you want to win, pay up homeboy. TT sessions are short enough that the Hoosier A7 may be a good choice, it'll come up to temp quickly and you aren't doing sprint races that would potentially see it fall off.
- If you like the photos that the track photographer takes of your car, he'd appreciate if you pay for them :-) I don't make all those announcements every weekend for nothing.
I ran TT for three years before moving to GTS2, managed to bring home some seasonal podium trophies in the now-dying TTD class at the time. The biggest thing I learned was that while "driver mod" can make up for some of the gap between you and the leader, it's really hard to make up that time on sub-standard equipment. I would corner balance ASAP, get new tires for March VIR, and explore options for the rear end if it's even necessary. The first two will absolutely help close that gap.
Thanks for the reply I’ll come find you In March! You make some good points, here’s my responses
1. No it hasn’t been corner balanced, another thing I need to add to the list thanks! I did notice an improvement after adding ballast so I’m sure it really needs to be done
2. The rear end is stock and open. No options to change it in the Porsche world unfortunately.
3. New tires I know! I’ll buy them this year, in the past I’ve had (and still do) have more driver skill improvements to make so didn’t want to make the investment. I’m actually the third owner of these tires and I’ve been running them for three years (almost every event), but my corner speed is the same as the 1st place finisher. They’re also not Hoosier, their BFGs. Finding those 3 seconds doesn’t look so hard now does it haha.
4. You got me. I just Paypaled him and will update the picture once I receive it. Shame, Shame, Shame
Also Congrats on the podium finishes!
Cheers,
stu
We started work on the cage this past week I couldn’t be happier with it. If you’re in Virginia and need a cage made send me a message Paul who is making mine is doing a great job and is reasonable.
In reply to adam525i :
It was a custom made bar and not a great setup Since the top anchors to the factory roll bar only. One of the downsides to Boxsters is there isn’t a way yet to add a roll bar and keep the factory convertible top.
t56mike
New Reader
1/7/19 7:02 a.m.
In reply to Box4VIR :
Try this for searching for aircraft lighting
https://m.aircraftspruce.com/catalog/elpages/panelpost13-15801.php
They have a 12 volt option for ordering
The bay of e has them under panel post led light
Awesome! I will be there racing in GTS2 that weekend and helping run UTCC/the rest of Friday.
The plywood splitter on my E36 is strong enough that you can stand on it, but it took a few rounds of cabling and brackets to make that a reality. "Standing on it" isn't necessarily the best strength test, but it does need to handle actual downforce at speed. The first iteration of mine was pretty weak, and photos showed it drooping pretty hard.
Quick update, last season was a blast, that being said I did wrecked the car, got it back together and then promptly blew up the engine during the first lap of the Grassroots UTCC event. Still a great season and the off-course incident and blown engine gave me some opportunities to complete some other projects
Here's an aftershot of the wreck (I hit a tirewall at turn 4 on VIR). Adding insult to injury my extended family was driving back from Hilton Head and stopped at VIR to watch me run. They had a great view of the wreck from the pavilion top deck and then to make the matters worse they didn't hot pull and instead left me in the tirewall for the heat. The good news is it was minor and only required a new radiator, head lights and other small odds and ends.
One shot right after engine blew. An accusump oil line was cut after hitting a drive axle.
I'll post a few of the projects to catch up. Here's the first one, replacing the blown motor.
My car had a 2.5L engine in it but these are getting a little pricey with the Spec Boxster guys snatching them up so I went with a 2.7L. The 2.7L uses a drive by wire throttle body and a valved cross over tube neither of which will work with my ECU, so I made a hybrid manifold by combining various parts off of both. And ya gold tape, why not. One other note, its absolutely terrifying how high you need to lift the car to get the motor in our out.
One unintended consequence of my hybrid intake was that it pushed the throttle plate further back, in its new location the factory intake tube no longer would work. I decided to ditch the factory intake that snakes around the engine and pulls air from the side of the car and reroute the intake to the rear window. I then installed aerospace snap vents in the rear window to allow air in (side note: apparently anything aerospace is insainly expensive, these vents were $17/pair). While I was at it I installed a NASCAR NACA duct I bought used off ebay for $9 bucks and ducted it to the passenger window, being in the middle of the car these engines don't get a lot of airflow.
One thing I didn't originally take into account is that I installed the intake in a low pressure zone on the car. I could have moved it but decided instead to remove the low pressure zone. To do this I installed vortex generators at the stall line on the roof. The idea here is the vortex generators, allegedly, will spin the air pulling high velocity air down to the skin of the car to speed up the airflow at the skin of the roof which helps the air to stick to the skin of the roof/rear window. This is exactly why airplanes use them as well, next time you're on a plane take a look at the wing near the fuselodge, there will be dozens of these, they decrease the stall speed by keeping the air "stuck" to the wing surface (by the way if I'm wrong please correct me! This is my understanding). The vortex generators will also provide more airflow to my rear wing. Will this work?...probably not but I had the spare aluminum so why not.
Interesting, is that enough of a disruption to make a vortex? I was envisioning the stick on ones you see on semi trucks.
$17/pair is insanely expensive? Seems really cheap to me
In reply to docwyte :
I guess not, they're just small pieces of rubber. I guess its all relative
I'm working on widening the car by 4" right now and am worried my front control arm design isn't strong enough. First here's some background info, I want to widen the car without spacers (in the front, rear will use spacers) so I don't increase my scrub radius. My solution was to lengthen all of the suspension arms, move the strut tower out and raise the struts in the hubs. I was able to use a lot of off the shelf parts but my adjustable control arms would not extended a full two inches. I tried to replace the adjustable portion with an adjustable rod end but it needs to be RW threads on both sides which doesn't seem to be available. My solution was to add a high strength steel 3/4" threaded rod and a 3/4' steel sleeve (see below). What are your thoughts? The adjustable portion of the arm sits on the inside (connects to the frame).
Here's the original hardware/ setup on the Elephant Racing adjustable control arms
This is the new setup with the thread rod and sleeve added
Assembled view
I'm a little rusty but if I remember my engineering right; I would not. The forces in the original design move along the lines of the control arm and essentially intersect at the ball joint. That's optimal. By moving the ball joint out like that the forces intersect at the spacer you made and now the distance between that point and the ballpoint is the length of the lever that's going to try and bend that spacer. If I'm wrong someone please correct me but my understanding says that is not ideal. It might be strong enough but in theory it's not the "right" way to do it.
spandak said:
I'm a little rusty but if I remember my engineering right; I would not. The forces in the original design move along the lines of the control arm and essentially intersect at the ball joint. That's optimal. By moving the ball joint out like that the forces intersect at the spacer you made and now the distance between that point and the ballpoint is the length of the lever that's going to try and bend that spacer. If I'm wrong someone please correct me but my understanding says that is not ideal. It might be strong enough but in theory it's not the "right" way to do it.
Thanks for the reply. I hope this doesn't come to custom parts. Sounds like it might.
