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Bolt on Exhaust for SPB?

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Old 02-17-2018, 09:22 PM
  #16  
mmuller
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Originally Posted by ace37 View Post

Did you notice if an H/X pipe did much? I’ve read somewhere on here it’s thought to be worth 4-5 whp. If true I’ll be considering that.
I personally didn’t see that bump with the systems we tested. I personally don’t use an exhaust with either of those features.
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Old 02-17-2018, 11:10 PM
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Matt Marks
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AWE's website doesn't list the system anymore. Several other AWE resellers have it on their site but list it as "discontinued". I have reached out to AWE and will post when I hear back.

Here is an picture https://uspmotorsports-gwh9ams6nbbjf...ercar_1280.jpg - sorry - RL doesn't want to let me embed it.
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Old 02-18-2018, 05:37 PM
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I searched and found Top Speed muffler is 18lb circa lighter then OEM muffler assembly. And in a dyno test the Top Speed gained 7whp on Boxster 2.5.

The bypass pipes by Top Speed are cheap, $125 set on Ebay, and they supposedly save each 7lb per side, so 14lb total between two sides.

Total weight reduction 30-32lb.

I will guess that maybe bypassing can gain 3whp to be safe: so total of 10whp by swapping OEM for Top Speed affordable parts.

Another aspect is I am in California and Laguna is my home track as is Sonoma. They have stringent noise regulations, Laguna 92dB I think.

Top Speed muffler with OEM cats was measured to be 90dB but I don't know at what distance?
Top Speed muffler and Top Speed bypass pipes were measured to be 94dB, I don't know at what distance: but I speculate that this system would pass Laguna, with at most a 90 degree turn at the tips.


Since I am in the midst of Spec Boxster build, this is for the moment the direction I was going to pursue, ready to pull trigger on exhaust.

If you have some data and suggestions I would appreciate to hear.
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Old 02-18-2018, 05:44 PM
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I'll add that Top Speed seems to also be available on Ebay as Generic, for a bit less, $250 instead of $380, but looks to be identical.
Not that we care for $100 savings, when considering the risk of somehow having an inferior product, but in this case I think that its same product - so the possibility to buy complete headers-back for $250+$125 = $375 is awesome.
Light (-30lb savings) and more power (+10whp perhaps) and quiet enough to pass sound checks (90-94 dB)
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Old 02-18-2018, 07:59 PM
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Originally Posted by mmuller View Post
I personally didn’t see that bump with the systems we tested. I personally don’t use an exhaust with either of those features.

Ok, then it sounds like the X/H contribution to performance is not something that is clearly established. Given the stock headers aren't equal length I wasn't sure how they would work unless a lot of time was spent designing and redesigning to sync up with the OE header design. In other words, I don't find that surprising!

Originally Posted by alpinaturbo View Post
I'll add that Top Speed seems to also be available on Ebay as Generic, for a bit less, $250 instead of $380, but looks to be identical.
Not that we care for $100 savings, when considering the risk of somehow having an inferior product, but in this case I think that its same product - so the possibility to buy complete headers-back for $250+$125 = $375 is awesome.
Light (-30lb savings) and more power (+10whp perhaps) and quiet enough to pass sound checks (90-94 dB)
It sounds like a very sensible off the shelf option. My only reluctance is I suspect a muffler with adequate sound reduction could be lighter weight and eliminate the bends in the system. A lot of folks/regions seem to just throw on straight pipes and call it good. I'm sure that is lighter than pretty much anything else and is also about as cheap of an option as you can get - for a simple straight pipe system I bet the cost is close to $200. But I'd rather not need earplugs to drive the car...

I suspect it would be pretty easy to have a local shop build a simple straight pipe exhaust with one straight through fiberglass muffler per side to get the sound more reasonable - something similar to what Lemming put together. (I lack both the tools and the talent to weld a system myself.) I suspect that would cost similar money to the already quite cheap topspeed system but offer the ability to use mandrel bent
304 stainless. I'm just thinking take out the tape measure, grab the Summit catalog, get an idea, and find a shop to do it for essentially the cost of the required materials + labor. Bring the parts after they check the measurements or buy their stock, whatever makes sense.

Based on reading up on hot rod forums and the like I am thinking 2.25" would be a good size for this motor, and 2" might be fine as well.
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Old 02-19-2018, 12:11 AM
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One other aspect to consider is heat and the concentration of it around the trans and axles. One of the reasons you see straight pipes is that mufflers retain a lot of heat. The 5 speed in the 2.5 Boxsters is known to be fragile with heat being a major influencer. There are ways to mitigate some of the heat if planned out correctly. In racing conditions, the heat soak in the components is considerably higher than the design spec for the components was from Porsche.
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Old 02-19-2018, 02:28 AM
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Originally Posted by mmuller View Post
One other aspect to consider is heat and the concentration of it around the trans and axles. One of the reasons you see straight pipes is that mufflers retain a lot of heat. The 5 speed in the 2.5 Boxsters is known to be fragile with heat being a major influencer. There are ways to mitigate some of the heat if planned out correctly. In racing conditions, the heat soak in the components is considerably higher than the design spec for the components was from Porsche.
Has fiberglass wrap been used? Thinking to motorcycling - insulation can make a world of difference.

Since I don’t have a tranny cooler yet I was happy to see that the catalytic converters which are presently kissing cousins with the transmission won’t be cooking there much longer. For heat management it’s at least easy to improve on what I have now.
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Old 02-19-2018, 02:57 AM
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Bends/no bends, OEM has pretty sharp bends, and in looking over dynos, even complete systems, rarely do you see more than 5whp on Boxster S for example.
The 7whp on the dyno I've seen of the ToSpeed was unusually high, it may not be true 7whp: dyno to dyno variations are huge, more than 7whp easily. So all I can say that given that we all want to believe aftermarket lightweight exhaust gives power.

So...given that I have seen so little gain with any system on dyno-sheets I've found, I am not sure that a bend or two makes huge difference: I have no direct dyno-tuning experience with Boxster specifically, so I am more than glad to be over-ridden, shown to be wrong.

If anybody has some dyno data to show actual gains, or losses, please, would you educate us?

Thank you.
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Old 02-19-2018, 08:48 AM
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Yes, exhaust wrap is part of the cooling solution available and used in some of the cars.
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Old 02-19-2018, 09:54 AM
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Originally Posted by ace37 View Post
I suspect it would be pretty easy to have a local shop build a simple straight pipe exhaust with one straight through fiberglass muffler per side to get the sound more reasonable - something similar to what Lemming put together. (I lack both the tools and the talent to weld a system myself.) I suspect that would cost similar money to the already quite cheap topspeed system but offer the ability to use mandrel bent 304 stainless. I'm just thinking take out the tape measure, grab the Summit catalog, get an idea, and find a shop to do it for essentially the cost of the required materials + labor. Bring the parts after they check the measurements or buy their stock, whatever makes sense.

Based on reading up on hot rod forums and the like I am thinking 2.25" would be a good size for this motor, and 2" might be fine as well.
That's pretty much what I did, lots of reading on the forums, then went to the Summit website. All-in-all I spent $140 and still have 7" of tubing left. I did not want straight pipes as I hate really loud race cars. With the turbo mufflers, my car can easily run a 93 dB event.

Originally Posted by ace37 View Post

Has fiberglass wrap been used? Thinking to motorcycling - insulation can make a world of difference.


I wrapped the headers and the exhaust up to the point of the mufflers to try to keep heat out of the engine bay and off the trans. I know that wrap will likely cause the headers to degrade faster, but they are so cheap, who cares.
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Old 02-19-2018, 09:06 PM
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Alpineturbo, I have the topspeed exhaust on my Spec Boxster (for sale, by the way). It's pretty loud. There's no way you can make sound a Laguna Seca. The Spec Boxster racers I know in the bay area put on the stock muffler or the Boxster S muffler from the same era to make sound at LS.

As for power, I didn't dyno before and after, but in the for-sale link above there is a dyno graph of the car with the topspeed muffler and the stock cats. Wheel horse-power: 192, torque: 176 ft-lbs. I've been told that replacing the cats with straight pipes is good for 5 more HP. If so, that would be 197, which I think is a competitive number, so I don't think the topspeed muffler is giving away too much to all the expensive custom systems.

Search Tom Stone's thread about his car for his post about his dyno experiments. http://986forum.com/forums/boxster-r...ter-build.html
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Old 02-19-2018, 10:49 PM
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Power is nice, but don't give up torque in a SPB. That's my advice.
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Old 02-20-2018, 12:54 AM
  #28  
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Dear Greg, and MMuller, thank you both for generous feedback and advice.

Top Speed is in the shop, we'll use it when at Thill, Sonoma, and see if maybe using resonator instead of bypass pipes quiets car down through turn-downs/turn-left tips enough to pass Laguna.
We have OEM and can get Boxster S muffler too.

MMuller Sir, giving up torque- are you suggesting that bypass pipes create a dip in torque curve?

Should be reflash ECU now that it is an option? To fill in the torque curve, if deep is evident.

Wonder since you have experience, using proper deep sump & baffle, Accusump, and meticolous maintenance schedule, a 140k mile healthy motor - daily driver - what is normal to expect life-span wise- how many events/seasons?

IMS is getting replaced. We're doing preventive maintenance, have CSF 3rd radiator in, and are about to install a larger oil cooler.

Thank you.
If you have suggestion for good flowing, light, quiet muffler(s), please shoot. Same for resonators.

In other cars we've used Magnaflow, but they are not light.
Burns is cool but I don't see any data how quiet/effective their products are: its all marketing jargon, zero data.
As engineers, we like some quantifiable information.

Happy Presidents Day Holiday
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Old 02-20-2018, 10:08 PM
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My comment on power vs torque was not about any specific exhaust or design, more that I see people focus the discussion on power. I have seen system make awesome power, but leave a hole in the middle of the torque curve.

The only flash allowed in a SPB is the OEM Euro flash. No other's permitted and they will be found if you have them (saw it several times last year. All the Euro flash does is write out the air pumps so you dont get a check engine light, so no benefit to hp or torque
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Old 02-20-2018, 10:29 PM
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Originally Posted by alpinaturbo
Dear Greg, and MMuller, thank you both for generous feedback and advice.

Top Speed is in the shop, we'll use it when at Thill, Sonoma, and see if maybe using resonator instead of bypass pipes quiets car down through turn-downs/turn-left tips enough to pass Laguna.
We have OEM and can get Boxster S muffler too.

MMuller Sir, giving up torque- are you suggesting that bypass pipes create a dip in torque curve?

Should be reflash ECU now that it is an option? To fill in the torque curve, if deep is evident.

Wonder since you have experience, using proper deep sump & baffle, Accusump, and meticolous maintenance schedule, a 140k mile healthy motor - daily driver - what is normal to expect life-span wise- how many events/seasons?

IMS is getting replaced. We're doing preventive maintenance, have CSF 3rd radiator in, and are about to install a larger oil cooler.

Thank you.
If you have suggestion for good flowing, light, quiet muffler(s), please shoot. Same for resonators.

In other cars we've used Magnaflow, but they are not light.
Burns is cool but I don't see any data how quiet/effective their products are: its all marketing jargon, zero data.
As engineers, we like some quantifiable information.

Happy Presidents Day Holiday
We have a private FB group for NorCal boxsters sounds like you are here?
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