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Old 11-04-2008, 11:40 PM   #1
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3.2L 987S Dyno Results

I have an AWE Tuning exhaust coming for my car this week. The plan is to have my car up on jackstands tomorrow night and start loosening bolts on the stock exhaust in preparation for the new exhaust's arrival on Thursday.

The Cayman boys have been reporting gains like 17 HP at the wheels. I purchased the exhaust merely to be loud and anti-social, but if there are real gains to be had, all the better.

I'm curious to find out how different the gains will be on a 3.2L versus the 3.4L, so I did a baseline run today at Dynomite Tuning off Miramar Rd. in San Diego tonight.



First run was in fourth gear, second run in third. Lost a little power on the second pull but not enough to say anything given the limited data.

237 HP /210 TQ. With the factory rating of 280 at the crank, that's pretty much spot-on for the standard 15% drivetrain loss calculation. Car has 50,800 miles on it, so I'm pleased.

I'll give the new exhaust a few days to burn in and then take it back to see what happens.
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Old 11-05-2008, 01:13 AM   #2
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Sweet, you have to love the torque curve on our cars, have fun,

Ed

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Old 11-05-2008, 06:49 AM   #3
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Thanks for sharing the results and posting them. I was curious about what the 3.2L on the 987 put down to the wheels. Looks like your car is right on the money.
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Old 11-05-2008, 10:30 AM   #4
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Thanks for posting the dyno graph. I've always wondered how much an 987 S puts out at the wheels. My 986 S has 240hp at the wheels with a little help from an aftermarket chip.

Quote:
Originally Posted by eslai
I have an AWE Tuning exhaust coming for my car this week. The plan is to have my car up on jackstands tomorrow night and start loosening bolts on the stock exhaust in preparation for the new exhaust's arrival on Thursday.

The Cayman boys have been reporting gains like 17 HP at the wheels. I purchased the exhaust merely to be loud and anti-social, but if there are real gains to be had, all the better.

I'm curious to find out how different the gains will be on a 3.2L versus the 3.4L, so I did a baseline run today at Dynomite Tuning off Miramar Rd. in San Diego tonight.



First run was in fourth gear, second run in third. Lost a little power on the second pull but not enough to say anything given the limited data.

237 HP /210 TQ. With the factory rating of 280 at the crank, that's pretty much spot-on for the standard 15% drivetrain loss calculation. Car has 50,800 miles on it, so I'm pleased.

I'll give the new exhaust a few days to burn in and then take it back to see what happens.
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Old 11-30-2008, 07:34 PM   #5
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a/f

I'm new to Boxsters, so forgive me if this has been covered before: Do Boxsters always run at 15:1 air/fuel ratio at full throttle, or is the A/F plot on your dyno test incorrect? I would expect more like 12:1 or 11.5:1 on a stock car.
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Old 12-01-2008, 06:02 AM   #6
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Quote:
Originally Posted by ACR MAN
I'm new to Boxsters, so forgive me if this has been covered before: Do Boxsters always run at 15:1 air/fuel ratio at full throttle, or is the A/F plot on your dyno test incorrect? I would expect more like 12:1 or 11.5:1 on a stock car.
IIRC, our 987S's are right about 11:1.
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Old 12-01-2008, 06:04 AM   #7
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Eslai, very cool! Good luck on your results.

I love my PSE. Did not get, nor did I expect, any HP gains. Just soulds great.

Hopefully you get some nice top-end HP improvements, and don't risk any low RPM torque or HP.

Report back ASAP.
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Old 12-01-2008, 11:16 PM   #8
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Whoops, I forgot to update this thread with my results! First off, the A/F readings were definitely screwed up on my baseline run--they had a problem with the sensor.

I just got back from a trip up the coast to San Francisco and back. The exhaust sounds great through tunnels and off cliff walls.

I posted this information (for the most part, I trimmed it for this post) a couple weeks back over on Cayman Club:


I did the work myself at Dynomite Tuning off of Miramar Road in San Diego. Jame there let me use the lift and helped me out when I ran into some installation snags.

I have a friend that refuses to work on German cars, and now I know why. These cars are not easy to work on. Getting the nuts off the pre-cat flange was a pain in the ass, requiring assorted sockets, U-joints and extensions used at non-optimal angles for torque application. The AWE flange is a nice, beefy piece of steel so it isn't flared for strength like the stock pieces. This made accessing the nuts a LOT easier.

So that leads me to my major bit of advice:

When working on a 50,000-mile car, heed the advice of others and use Liquid Wrench, even on a southern california car with no rust.

So yeah, I snapped one of the studs on the pre-cat. Jame had to press it out and we found a bolt that matched perfectly (threads and length and nut diameter, even!) but I'm not sure how permanent of a fix I consider that. I have no idea what the dealership would charge me to press in a new stud, or even if they'd bother--they might just tell me I have to buy a new pre-cat, and that would make me a Sad Panda.

The next little snag I ran into is that the stock exhaust tips don't fit very well onto the AWE Tuning muffler ports. We had to get pretty gorilla on the T-pipe in order to widen it enough to slip over the ends on the new exhaust. I'm not sure if we were supposed to need to do that or if the pipes on the AWE Tuning mufflers are of slightly larger diameter than stock (and I would assume the replacement tips that AWE sells would probably match that enlarged diameter better).

Okay, so with the install out of the way, I gotta say that this exhaust sounds awesome, EXCEPT at low throttle application in the 2000-2500 RPM range. As others have stated, there is resonance/drone. It is LOUD, for sure. It is only annoying when cruising uphill, when the car needs a bit more throttle in order to maintain speed. Otherwise, when you're really accelerating, you pass through this range quickly enough for it to not be an issue.

I expect to be able to get used to it, and if I decide that I'm a big pussy, I'll switch to a Capristo instead.

Anyhow, the sound when accelerating is pure heaven. Everyone that's heard the exhaust says it sounds amazing. Even the girlfriend loves it.

I have a bit more vibration than before, and maybe I'll have to play with the exhaust hanger a bit to see if I can get that to go away.

One other thing I noticed--the muffler cans do not sit perfectly symmetrical next to the tailpipe cutout on the bumper cover. Has anyone else noticed this? On my car, the passenger-side can is sitting about half a centimeter farther to the right than the driver-side one does. I left everything loose when I mounted it all up, played around with fitment as much as possible but I couildn't get any better results. The muffler placement is mostly located by the pipe coming off the pre-cat and that's pretty rigid. It's not something that's really noticeable, so it doesn't bother me, but something I thought I'd mention.

I did this mod for the sound more than anything else, but I did dyno test it, as I was curious to see how it would fare on the smaller motor.



I saw an 8-horsepower gain, which is pretty much what you'd expect.

You'll notice how rich the car runs at WOT through redline--it rides at an A/F ratio of about 12.0. I can imagine how some chip tuning could really release some power. (Ignore the A/F line from the baseline dyno run--the sensor wasn't working right that day. They had it fixed tonight).

At the same time though, perhaps this richening is the ECU's response to detonation, or programmed response to prevent detonation, from the 91-octane gas.

While I didn't gain all that much power (and the butt dyno had already told me that), I was impressed to see torque gains across the board. I had expected to mainly gain power on the top end--the gains down low were a pleasant surprise, and they maintain the smooth and flat torque curve that these cars have, leaving the power delivery characteristics pretty much the same as stock.

I'm looking at about a 15% drivetrain loss and that leads me to believe that I now have about 290 horsepower, up from the 280 stock. Fine by me.
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Old 12-02-2008, 02:00 PM   #9
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Quote:
Originally Posted by bmussatti
IIRC, our 987S's are right about 11:1.
I think you're getting the compression ratio mixed up with the air/fuel ratio. An 11:1 air/fuel mixture is extremely rich and the engine would run very poorly. Optimum A/F mixture is around 14.7:1. Eslai, you should definately get a tune done, you'd probably pick up a nice amount of hp and improve the curve even more as you suspected. The computer doesn't richen up the A/F mixture if you run low octane, it just pulls timing so the 91 oct gas isn't why your A/F is rich. Your engine is definately not running at it's peak at 12.5:1
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Last edited by Adam; 12-02-2008 at 02:24 PM.
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Old 12-02-2008, 05:00 PM   #10
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Yeah, a chip tune costs less than $1000, but I don't know if I want to bother, what with Cali gas being what it is and all. Might not be cost-effective. Lean things out a bit, get knock, ECU pulls timing...
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Old 12-02-2008, 05:31 PM   #11
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Quote:
Originally Posted by Adam
I think you're getting the compression ratio mixed up with the air/fuel ratio. An 11:1 air/fuel mixture is extremely rich and the engine would run very poorly. Optimum A/F mixture is around 14.7:1. Eslai, you should definately get a tune done, you'd probably pick up a nice amount of hp and improve the curve even more as you suspected. The computer doesn't richen up the A/F mixture if you run low octane, it just pulls timing so the 91 oct gas isn't why your A/F is rich. Your engine is definately not running at it's peak at 12.5:1
Nope, at full throttle, the optimum power is made at about 12:1-12.5:1 AFR. Stoic is good for fuel efficiency at lower loads, but there's more power at more rich mixtures due to flame front speeds and the inefficiency of combustion.

Last edited by blue2000s; 12-02-2008 at 05:34 PM.
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Old 12-02-2008, 10:40 PM   #12
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Correct. I'd imagine any chip to not pull it back more than to like, 12.5:1.
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