Spec Boxster Build

[njbray]

Originally Posted by rastta

Actually they have several - I think up to 7 unlimited sound events per year. The rest are either 90dB or 92dB.

The track is owned by Monterey County. Therefore it's limits are set by the Monterey County Board of Supervisors. The limits were put into place and more aggressively enforced due to actually one guy who inherited his home in Carmel Valley - a group called the Highway 68 Coalition out of Salinas.

I can pass sound by lifting and running supertrapps on the exhaust. Kills power above 4k but at least it allows me to run there. I've been black flagged once while running the trapps at 94dB. Car is normally around 98dB. I only run there one weekend a year with the Audi Club - the rest of the time I run elsewhere where the sound limits are reasonable.

That's good to know. I love Laguna Seca - We have been going to events there for 20 years. When they had the Ferrari historics it was amazing to hear the F1 cars on the track - the noise was echoing off the surrounding hills! You could hear them all the way around the track.

[Chuck W.]

That track was built in 1957 when there was nothing around there. Then they build homes there and complain about the noise. It is like buying a home under an airport runway approach and then complaining about the noise.

[thstone]

So, here is the story of what we did to reduce the sound over the weekend...

Fix #1/Saturday evening

Weld on a pair of SuperTrapp diffuser's to my existing TopSpeed Pro 1 exhaust. This failed sound on Sunday morning and did really reduce the sound level to any appreciable degree. The red goop is thread locker to keep the diffuser bolts from coming loose.



Fix #2/Sunday morning

Cut off the SuperTrapp's, weld on an 8" bullet muffler, and weld the SuperTrapp's onto that.

This solution did the trick! Looked like crap, but met the sound requirement without completely restricting the exhaust flow and killing the power. Good enough to get me up to 2nd place in the race and finish 4th. I'll take it.





And now, since I Frankenstein'd my TopSpeed, I bought a new TopSpeed and will swap it in next weekend to get back to the original racing setup.



In the future, all of this could have been avoided by simply buying a used OEM stock Porsche muffler from eBay and bolting it on before the event. The stock exhaust is very quiet without losing much power.

Thanks to Brad Roberts and Vali Motorsports for all of the support! They saved the weekend for me.

[jsceash]

It's not the only race course that has these crazy restrictions. Lime rock has the same restriction so I can't run there (90db).

[thstone]

Here are a few pic's from last weekend at Laguna...

On the grid, thumbs up, ready to rock!


Leading Paul Young's #17 Dead Pets Racing 911 hard into Turn 5...


Darin Kajoika's #265 chasing me up the hill to Turn 6...


Looking tidy coming out of the turn...


Using all of the track past the bridge on the uphill to Turn 6...

[bkovac]

that suit is just getting bigger and bigger

[thstone]

Originally Posted by bkovac

that suit is just getting bigger and bigger

Haha! Thanks, I'll talk that as a compliment!

[jcslocum]

Is it known where the microphones for testing are located?? We used to run some VERY loud bikes and adding a 90 degree turn would point the sounds away from the mics. They were always placed in a similar spot on the outside of the track, worked for us at the time.

[rastta]

Originally Posted by jcslocum

Is it known where the microphones for testing are located?? We used to run some VERY loud bikes and adding a 90 degree turn would point the sounds away from the mics. They were always placed in a similar spot on the outside of the track, worked for us at the time.

Yes - in the small building at the exit of Turn 5 as you accelerate up the hill. If they are anticipating a very loud group - they will have a roving sound guy who moves to different point along the track.

[thstone]

Originally Posted by jcslocum

Is it known where the microphones for testing are located??

As Joe said, just after the exit from Turn 5 as you go up the hill...

[thstone]

** Weight Update #5 **

Spec Boxster minimum weight with driver and fuel is 2,650 lbs. My goal is to be able to manage the weight of the car by adjusting the fuel load at the start of a race so I am near the min weight at the end of a race (with some margin for error).

Last weekend, total weight was 2,683 lbs with a 1/4 tank of gas. Subtracting 24 lbs for fuel (6 lbs/gallon x 4 gallons), says that the car/driver weighs 2,658 lbs.

If you remember, weight update #4 had the car/driver at 2,654 lbs with no fuel. Then I removed another 16 lbs (11 lbs for the lexan windshield and 5 lbs from my own weight, so I was predicting the car/driver total to be 2,638 lbs - but got 2,658 (or a difference of 22 lbs).

This means that I am experiencing something like 0.83% variability in weights (8 tenths of one percent). My thinking is that this error is primarily driven by different scale accuracy and fuel gauge accuracy but the error budgets don't add up.

Most scales used for weighing cars say that they are accurate to 0.001% which would be around 3 lbs and the fuel gauge might be off by a gallon, so another 6 lbs of error for a total of 9 lbs, But I am seeing a difference of 22 lbs.

So, I plan to reduce weight by another 13 lbs (22-9) to try and account for the variability on the high side and then get another weight check at the next event to see where I stand. At that point, I should be within the measurement error bounds and if I end up being too light, it is easy to add more fuel to be sure that I am at min weight at the end of a race.

[thstone]

Batteries.

Most of the cars in Spec Boxster run an Odyssey Extreme battery. They work great and weigh quite a bit less than a standard full size battery.

Well, they work great until they don't. Everything will be fine and then the battery will be dead as a doornail without any warning or hint of running down. This has happened twice - one time at the track and Brad Roberts had to R/R the battery in 5 mins with me suited up in the car so I could make a race.

The last thing that I need is more stress or something else to worry about at the track. So, now I treat the battery as a standard maintenance item and replace it every 12-18 months (around $150).

[specboxCO]

Originally Posted by thstone

Batteries.

Most of the cars in Spec Boxster run an Odyssey Extreme battery. They work great and weigh quite a bit less than a standard full size battery.

That's a huge battery for a Spec Box. It weighs over 26lbs, puts weight high up in a bad spot. Most guys in TX & CO run a DEKA ETX14 or ETX12 which can be bought for $60 and weigh 12 or 10lbs respectively.

Do yourself a favor and take this opportunity to save 16lbs of weight and some cash.

Edit: Pull the cutoff switch when you park the car and you never have to worry about a dead battery.

[thstone]

Originally Posted by specboxCO

That's a huge battery for a Spec Box. It weighs over 26lbs, puts weight high up in a bad spot. Most guys in TX & CO run a DEKA ETX14 or ETX12 which can be bought for $60 and weigh 12 or 10lbs respectively.

Do yourself a favor and take this opportunity to save 16lbs of weight and some cash.

Edit: Pull the cutoff switch when you park the car and you never have to worry about a dead battery.

You are correct.

However, because this is still a street legal car and I drive it to events, it needs to start reliably (as in every time) - even after a night in the hotel parking lot at 30F during the winter. Unfortunately, I don't have the luxury of jump starting from the truck that was used to tow the trailer if the Boxster battery doesn't have enough juice.

But your point is a good one and I'll take another look at them...

[seningen]

Originally Posted by thstone

You are correct.

However, because this is still a street legal car and I drive it to events, it needs to start reliably (as in every time) - even after a night in the hotel parking lot at 30F during the winter. Unfortunately, I don't have the luxury of jump starting from the truck that was used to tow the trailer if the Boxster battery doesn't have enough juice.

But your point is a good one and I'll take another look at them...

Street battery and a track battery.

I know storage space is probably a premium when you travel but it's an option.

Mike

[jsceash]

Originally Posted by seningen

Street battery and a track battery.

I know storage space is probably a premium when you travel but it's an option.

Mike

The holder for the Odyssey PC925 is different than the smaller deka ETX14. So He have to have both and replace the tray as well.

Tom, with a full electrical system car I'm OK for about 6 week in cold weather then I have to run the car or charge it. I also run the PC925.
Jesse

[Greg Holmberg]

Useful information about maintaining Odyssey batteries.

Dry Cell Batteries - Jay Leno's Garage

I learned: don't use a BatteryTender, it's not designed for AGM batteries, and will shorten their lives. Use an Odyssey or CTek charger.

[jaykay]

Originally Posted by thstone

Batteries.

Most of the cars in Spec Boxster run an Odyssey Extreme battery. They work great and weigh quite a bit less than a standard full size battery.

Well, they work great until they don't. Everything will be fine and then the battery will be dead as a doornail without any warning or hint of running down. This has happened twice - one time at the track and Brad Roberts had to R/R the battery in 5 mins with me suited up in the car so I could make a race.

The last thing that I need is more stress or something else to worry about at the track. So, now I treat the battery as a standard maintenance item and replace it every 12-18 months (around $150).

Tom I have used one of these on in my boxster for a good 5 years. If you are able to keep it plugged in on a modern Ctek when not in use, you should get considerably more life and reliability out them. The Ctek will give you a mini battery reconditioning program while the car sits....then again I don't live in the desert!

[jaykay]

Tom,

What suspension bushing kit are you going to put it when you get to it?

[thstone]

Originally Posted by jaykay

Tom,

What suspension bushing kit are you going to put it when you get to it?

I'm not sure yet. Need to check the rules and see what my options might be. The suspension refresh will probably happen over Thanksgiving or Christmas so I have a little time get the parts together. I'll post up info when I have it.