Coloradoheel

If you've not run your SPB in any real endurance racing (something more than the paltry 60-90 minutes with PCA) and you've questioned durability/reliability, I'm here to quell those concerns (and brag a bit).

Just ran the 24@5280 with WRL at High Plains. A true SPB runs in GP1 (classes are GPX, GP1, GP2, GP3, GP4). 10a Sat - 10a Sun race. 46 cars total. 3 in GPX, 12 in GP1 (5 Boxsters, including two 2.7L). I also run this car with PCA, NASA and SCCA.

My SPB is true to the rules. Donor car/motor had 52000 miles - now at a little over 60000 miles. Compression was great when I bought it - and continues to be - so I've never cracked the case (IMO - if it ain't broke, don't mess with it). Only mods for this race (that will be removed before HPR PCA in 2 weeks) are a 996 brake kit, and auxiliary lighting.

Over 1500 miles at race pace in that 24 hours. 2 Boxsters went out early (sheared oil pan and the other had a half axle that broke loose and caused damage to the sub-frame) leaving me with 2 Boxsters that are built for WRL (faster and with greater fuel capacity) other primary comp remaining was a stout M3 running its 205hp tune, another M3 and a Vette.

I lost one half of my exhaust within first 2 hours (have not yet diagnosed why) and the other half just after dark. Trans cooler pump stopped for a couple hours but we walked it with a hammer around midnight and it came back on.

Not only did we finish (the car has completed all 4 WRL events it has entered (12 hour, 8/8 hour, 12 hour and 24 hour - podium finish in 3 of the 4) but we won - GP1 and Overall (beating an NP01 and a Subie STI) - ahead of the M3 (2 laps + 47 seconds) and the Vette (5 laps).

They may have been built for sprints initially, but I highly recommend endurance racing in them. They don't quit and they perform quite nicely.

FeuerRacing

I suggest you keep the lighting so you can flash people to let you pass!

Coloradoheel

Just for you pal!

jaundice

That's great news!! I'm getting mine ready for Hallett and then CoTA. Spent Sunday shaking it down with FeuerRacing. A big shout out to him and JG for a fantastic day!

gums

I'm starting to think that these cars are ideal enduro cars as well, now that I've gained so much confidence in mine and developed it. The car is like a tank, really strong! I just came from the PCA Club Race at T-Bolt, ran every session, three sprints and the (paltry) 60 min enduro and the car is ready to for more. Needs nothing and never skipped a beat.

Streak

Ran the 4 hour Vanderbilt Cup at Summit Point a few years ago in mine. Won overall. The only two cars to finish the race were the two SPB's.

Coloradoheel

Looking forward to running against you. Hallett may be out due to work BS, but COTA is a definite go.

Coloradoheel

Initially - after the build - I had some ongoing braking issues and some overheating issues. Once those were resolved, it has been game on. Tank is the right word. Damn car won't quit.

Greg Holmberg

Two Boxsters competed in the NASA 25 Hours of Thunderhill last December in class "ES".

Both Boxsters were entered by Cervelli Technical Service of Wheat Ridge, CO. There are some nice photos of the cars at the race here. The Boxster drivers were: Chris Cervelli, Chad ***, Steve Dunn, Joe Bunton, Glenn Conser, Chris Sarian, and Robert Ames.

NASA puts SPB in endurance class E1. Cervelli says they ran in ES not E1 so that they could refuel using NASCAR dump-cans, instead of 5-gallon jugs as required in E1. Since they didn't mention any other reasons for ES, I'm going to guess that the cars conformed to SPB rules.

Their fastest lap was 2:04.4 (with bypass). One didn't finish due to an engine bearing failure, and the other finished with 590 laps.

The overall winner, an Audi R8LMS, did 690 laps. The highest-placing 2016 Mazda MX-5 Cup (factory) car did 562 laps in class E0.

Finishing 590 implies no major failures. I'm kinda surprised that the 986 gearbox made it 25 hours!

According to their Facebook page, they rebuilt the engines of both cars before the event. I hadn't heard of crank bearing failures before in the 986 engine, so I was surprised. But apparently, they made some error in assembling one of the engines. The factory-assembled ones don't seem to have a problem with crank bearings (as far as I know).

Coloradoheel

I know Chris well - and his drivers. Good dudes all-around.
For Thunderhill caliber competition they did very well.
Chris was in my class this weekend in one of his cars (with Steve Dunn as a driver). The car was out within a few hours due to a smashed oil pan.

I did not rebuild my motor before this weekend's event. In fact, I've never cracked the case. 60000 mile motor with 9000 racing miles on it.
I did rebuild my spare tranny - new bearings, synchros and a new 3rd gear. When I climbed in for my first stint at 8p, tranny temp was almost 260°. Turns out the cooler pump stopped. As a result of the temps and general hammering it took, 3rd gear was feeling a bit sketchy.

At next pit stop we hit it with a hammer and it cranked back on - never to climb above 180° for the remaining 12 hours.

The tranny does need another rebuild before the next endurance event. 3rd is definitely hanging by a thread and 2nd felt a bit off as well.

Coloradoheel

I also run ES with NASA for the fueling reasons. It hurts heavily when I compete against tune able E36 because they will run a 225hp tune for ES and I can't hang with that in an SPB. That said, the box is better on tires and brakes so it keeps things close in a NASA 3 hour. I think I'm a 6 hour I could take the E36s.

CTS

Correct, the factory assembled engines, as well as the engines we assemble, don't have problems with crank bearings. Until said bearings run without oil for a sufficient time to fail that is.

ALL M96 race engines, and especially those installed in mid engine cars, do not have a 100% reliable supply of oil to the main and rod bearings under racing conditions. After enough time, the main bearings and then the rod bearings fail and the engine very quickly throws a rod.

The 2.5 engines, with their low rev limit and short stroke, tolerate the interruptions in oil supply pretty well. They also keep more oil in the sump compared to the longer stroke engines.

The failed engine (which was a 2.7) at Thunderhill was the result of losing oil pressure for short period of time at 100% throttle and at over 7000 rpm on one corner every lap. The 2.5 powered car did not suffer the same problem due to its decreased windage in the crankcase and lower rpm at the same point on the track.

I agree with Steve that Boxsters have wound up being a great endurance racing car. The oil system is the big issue though, and all of these cars are eventually going to have engine failure because of it.

The transmission does not last forever either because the 3rd gear idler is very small and the transmissions tend to run very hot and are difficult to cool effectively.

Other than these issues they are pretty indestructible as Steve mentioned. My two cars have run about 32000 track miles combined, and their reliability record, in spite of the oil system problem, is as good as any other Porsche race car I have run. Considering the cost per mile is only a fraction of that of a GT3 or air cooled car, it is frankly amazing.

BTW, congrats on winning that race. It is an incredible achievement for anybody.

Chris Cervelli

jaundice

Chris
Are you running accusumps in your cars? My 2.7 doesn't have one and there seem to be mixed opinion amongst the spec boxster guys whether it's needed or not? I'd love to save the weight and the complexity, but also want a motor to last as long as possible. We are cutting the rev limiter back to 6800 on the 2.7 since we have so many different drives.

Coloradoheel

Thanks Chris. Means a lot coming from you. See you on the 5th.

Coloradoheel

Can't speak to the 2.7 but I do not run accusump in the 2.5.