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Love the build. And yes, buying a prebuilt race car is much cheaper but only because someone else already got to have all of the fun building it!
Doing something similar with an 05 Boxster S. I’m at 2750# and have another easy 100#’s but the $/lbs of weight savings starts increasing exponentially after that.
The advice I was given on wiring is cut 6 wires, and then try and start it. Rinse and repeat. It takes longer but it seems to be the right level of detail if you don’t do it everyday. Leaving the necessary wiring for a future owner to reenable traction control or reinstall headlights are a few mistake I’ve made in the past. I got about 18lbs of wire out of my 996 if I remember correctly. I worked my way from the fuse/relay box out instead of the connector in.
Also, I highly recommend Matt on the data side. I’ve been putting together an AIM MXP/VBOX system with ECU integration on CAN1 and running tire pressure, temp, and a Bosch M5 ABS on CAN2. He has been invaluable at helping with the design details, sourcing parts and protocol integration support.
Good luck and can’t wait to see how your build turns out.
What is the plan for data? I'd love to help you out and maybe we can make the system match the coolness factor of the rest of the build?
I plan to use my Solo 2 DL. I will need to set it up for multiple cars as I use it in My Mustang GT track car. It has firmware for that car. I would like to add the Boxster OBDII data as well.
Other up dates:
Still haven't selected my roll cage fabricator but I have narrowed it down to 2 local shops.
Power steering: Prevent over heating issues: Reduction pulley adds 10 point and may not be enough to prevent over heating, Adding a PS cooler, I believe is no points or go electric, adds no points.
Exhaust: Remove the cats and maintain sound level at or below 93 db. Since I don't have the euro exhaust manifold PN and don't want to add points for headers, I will cut off the cats and fab the exhaust to small resonators or mufflers. More research is required here. What are you spec racers using that will not be too load?
Windshield I'm leaning to Poly Carb to make my weight goals.
Pop up spoiler: I will remove the mechanism to reduce weight and fix it in the up position.
Bumpers: Machined away material and removed the impact dampers to reduce weight pics to follow.
Wheel studs: Need to add long wheel studs.
More to come...
Last edited by ChampRacerJ; 11-23-2021 at 10:23 AM.
I plan to use my Solo 2 DL. I will need to set it up for multiple cars as I use it in My Mustang GT track car. It has firmware for that car. I would like to add the Boxster OBDII data as well.
Power steering: Prevent over heating issues: Reduction pulley adds 10 point and may not be enough to prevent over heating, Adding a PS cooler, I believe is no points or go electric, adds no points.
I haven't talked to anyone that's actually battled a power steering overheating issue yet, but I've decided to go with the electric PS kit. I like getting the pump closer to the rack and will take a few extra hp and a few less lbs.
Exhaust: Remove the cats and maintain sound level at or below 93 db. Since I don't have the euro exhaust manifold PN and don't want to add points for headers, I will cut off the cats and fab the exhaust to small resonators or mufflers. More research is required here. What are you spec racers using that will not be too load?
I have the 2.5L engine version of these on my SPB along with the Top Speed/Circuit Works/etc. style exhaust. Saves a ton of weight over stock and passes sound at Lime Rock, Palmer and Club Motorsports in NH, all are 93db or lower. Im not up the with the exact points/parts penalty system for Champ Car but I can't imagine any penalty wouldn't be worth getting rid of the boat anchor that is the stock exhaust but I could be wrong
Fun project. Looks like some solid suggestions from the community so far. My .02:
You may want to reconsider the fixed doors. Ingress is one thing, but egress is the important thing, especially after a crash. Gut the doors and cut the inner skin out. You can also remove the door stays to lose some weight. I’d recommend a full containment seat with halo braced to the roll cage. Don’t scrimp on the safety. Ask me how I know.
You can get a fair amount of weight out by thinning the wiring harness. It’s not too difficult with the car gutted. If you have the time and patience, the easiest way is to remove the harness and lay it out on a long bench. Trace each wire and remove end to end. Good opportunity to dig into the wiring diagrams also.
Remove the handbrake, from the handle all the way down to the rear brakes.
You can remove the bumper bars and 5 mph attach shocks if you want. There’s a lot of weight, and you don’t need them until you need them.
Remove the charcoal canister fueling system.
For exhaust, remove the cats. You’ll never regret that. Retain the forward O2 sensors in a custom exhaust or buy one of the SPB specific aftermarket exhausts. I really like the Patrick Motorsports exhaust. No affiliation.
For power steering, install the underdrive pulley. Add a PS cooler if you’re going to be running in high temp races down south.
For endurance racing, add a deep sump spacer and baffle kit for additional oil.
Replace all four wheel bearings. Repack each bearing with high quality high temp bearing grease.
I plan to use my Solo 2 DL. I will need to set it up for multiple cars as I use it in My Mustang GT track car. It has firmware for that car. I would like to add the Boxster OBDII data as well.
For the data, the OBDII on a 986 isn't really useful. If this is an endurance car, you're going to want some good engine health information (oil temp, oil pressure, coolant temp, etc) to maintain the car. With multiple drivers, brake pressure and throttle position will make a big impact on coaching and improving the team. I would suggest a rethinking of the data plan.
Guys, Thanks for all the input.
As for data if I can't get anything useful off the OBDII, I will add Engine oil temp, press, Trans oil temp, Water temp, Fuel press (diagnostics). Dream stuff: add ride height sensors for Aero development.
Weight reduction: I will remove the hand brake, Canister and evap is all gone, bumper F and R alum channel machined away excess material. Pics to follow, Bumper shocks -removed. Steering column excess material to be removed. Wire harness.. Ugh it daunting so I haven't started yet. Exhaust fab to start after cage is completed. PS undecided. I've raced many cars with the PS just removed without issue. I assume this has been tried on the 986 without success. Can someone comment on that experience please? A PS cooler adds points, a reduction pulley added points. So if I must have PS I'm leaning toward electric pump.. I missed the LN Engr sale....
Progress... Windshield is now removed after photo taken - to be replaced with Polycarb.
Initial main hoop fitment Initial Main Hoop Fit Door panels lightened
Problems? I started to work on the exhaust. Pulled the exhaust manifolds and found a lot of oil in the secondary air passage one bank. The other side was worse with oil and milkyness (presents of water in oil). The exhaust manifolds most likely hasn't been off the car in its 18 years life and 97K miles. Is this normal or the indication I have a bigger issue?
Note: The AOS was bad and I replaced that. Intake was full of oil from the failed AOS. Could that also get into the secondary air system? How about the water can that be an external source into the secondary air ie even form years of moist air condensing water over the 18 years of life? Or a cracked head to water jacket? I can pull a vacuum on the cooling system (cooling system service tool) The cooling system will hold the vacuum for a while certainly not for hours. Coolant is clean looking and wasn't low when I purchased the car. I have no other history.
Edit: Duh at engine operating temp all water/moisture would evaporate so this must be new accumulation from repeated cold starts and not getting up to operating temperature.
Last edited by ChampRacerJ; 01-02-2022 at 08:54 AM.
This is an exciting process. We raced chumpcar back in the old days when you had to print off craigslist adds to prove your car was worth $500!
You will find most of your answers from the Spec Boxster crowd on trimming down weight. I raced spec boxster and built a few cars, getting down to ~2450lbs is not easy to do even with lightweight fiberglass hardtops and lexan windshields etc.
You can delete the entire secondary air injection system, this will save you about 5-7lbs. There is a pump, a crossover tube, and a IIRC one or two wires you can remove. The block off plates can be bought from Porsche, just google "secondary air injection delete kit Porsche."
My experience with cutting wiring harnesses is to cut the major unnecessary features out of the harness, but don't go to crazy. I spent a lot of time cutting down a harness to save maybe and extra 5 lbs, the 20+ hours worth of work to do this and frustration was not worth it to me.
As mentioned before by a great Spec Boxster racer with lots of experience, I would 100% replace the and re-pack the wheel bearings, this is much easier to do while you have time and is a known issue on Boxsters and something that will definitely rear its head when you start pounding on it for hours at a time. The questions I always asked myself when preparing for an endurance race was "If I'm going to spend this much time and money to enter this XX hour race is it worth not doing these $50 wheel bearing to risk not finishing?" That's pretty much how I proceeded with everything and yes it does add up.
One other thing that breaks and can leave you stranded that no one ever things about is the plastic gas pedal, I had one of my driver's break one and if you don't have a spare or a replacement the car ain't going anywhere!
Up-dates:
Fabricated Exhaust is done. These 2 1/2" pipes will dump into individual mufflers and exit straight back in a dual exhaust fashion. I'll be using only one O2 sensor per bank.
11-21-2021, 02:29 PM
