Which exhaust?

[Dr K]

When I pick up the replacement muffler for the GHL (yes, I'm finally giving up on "repairing" the other one...), I'll have 2 complete exhaust systems for the coupe: A GHL (stainless steel) system with headers, extension pipes, and 2-in, 1-out low-resistence muffler; and old-style 1-5/8 equal-length-pipe headers and megaphones (I actually also have a pair of Flowmasters that some day I'll fab up to go on the equal-length headers--would be quieter than the megaphones).

The GHL headers are short pipes to a collector. Charley Murphy says this is the way to go for high-RPM torque and HP, but running a stock class car, I can't chip it or disable the rev limiter so I'm not sure I'd get the full benefit of this.

Here's a photo: http://www.pelicanparts.com/catalog/images/john1/911_header_3muffler.jpg

INFO (http://www.pelicanparts.com/catalog/shopcart/911M/POR_911M_EXHprf_pg2.htm#item)

The headers will certainly be loud, and maybe have less oomph at the high end of the rev range, but both Steve Weiner and a very, very fast E-class Dorki swear by them for low-end torque. At VIR, I found I was in 3rd gear in places I used to drop to 2nd gear (turns 1 and 4), and at Summit Point I'm seriously thinking of taking turns 3 and 10 in 4th as I run out of revs before track out.

Here's a photo:

http://forums.pelicanparts.com/uploads18/911+race+parts+Webber+kits+0051282823491.jpg

http://forums.pelicanparts.com/uploads18/911+race+parts+Webber+kits+0041282823531.jpg

INFO (http://forums.pelicanparts.com/porsche-911-used-parts-sale-wanted/560882-wts-911-headers-megaphone-pipes.html)

So I'll open this up for opinions. One other question - the headers have the thinner flange, like an earlier car than my 3.2 Carrera. I realize the problem with putting a thick flange on too-short studs, but can I put the thin flange on my 3.2 without problems?

[Dr K]

Bump...

[Jase007]

I'll bite. :)

I'd go with the headers, with the thin flange, for the low end torque.

Thinking:

if you get out of the corner better than the the guy you want to pass (timing, torque, racecraft...) then you won't need the high end (as much) to try and get by him at the very end of the straight.

In your mind which has less risk:

1.Do you want to have the extra couple of mph to try and outbreak the guy ... typically decelerating from a rapid rate of speed or,

2. Do you want to time your run and clearly make your move early and see and "be seen" before you get to the "crisis moment" :lol:

You don't have custom gears so the rpm drop between gears on a stock 915/G50 is H.U.G.E. Thus, you'll likely be in a single gear longer b/c you won't have the typical DE line to follow (traffic, car positioning, lappers, getting lapped, crashes, "oh st*t" moments, etc...). Accordingly, you don't need to maximize a narrow "power" high-rpm band (6-8K rpm) and consequently don't need the high rpm setup.

Simply: where are you going to start to be most aggressive, low(er) rpm moments (slower corners) or high-er rpm moments (end of straight diving inside in braking zone)?

*eventually, you'll want both. Torque off the corners and high rpm oomph. Can't mod the motor or chip... and motor is built more for torque so .. maximize that resource. Almost a six and one 1/2 dozen of the other conundrum...

** what class are you running?

[rs911t]

One other question - the headers have the thinner flange, like an earlier car than my 3.2 Carrera.
The headers I put on my 3.2 have the thinner flange. They go on fine, but you cannot use the existing barrel nuts as the studs are too long.

[Eric S]

For Ben's sake, make sure it is quiet enough for effective communications with a Chatterbox; while talking, not yelling. I assume that is what configuration 1 with the GHL muffler is for...

[good hands]

You know my opinion as far as torque... and the GHL probably weighs double ?

[smdubovsky]

I was hoping we could just give you the cold shoulder a little longer but since others have replied... :D

The GHL headers are short pipes ... says this is the way to go for high-RPM torque and HP

IMO, GHL won't give you more top-end hp. Those primaries are impossibly short. Even 16,000rpm sport bikes have longer headers. Look at every race exhaust porsche has ever made (which are mostly interested in high-end hp) and they have longer tubes just like your headers. The GHLs use short tubes for cost savings and to make the heat boxes easier to fab. Turbos are about the only things that commonly use primaries that short (and only because they aren't as sensitive to equal length designs w/ the tons of backpressure a turbo generates.)

That said, megaphones are obnoxious and prob fail most (all?) noise rules. Fab a muffler before you run them. You can put spacers (or old slightly larger bolts) under the barrel nuts to compensate for the thick/thin flange thing. Or just use regular nuts. There is so much clearance w/ headers you can get a normal wrench on them easily.

[Dr K]

Thanks, everybody. Headers it is. Megaphones for immediate use, and will fab up a mount and connections for the Flowmasters when there's time.

[HoodPin]

Thanks, everybody. Headers it is. Megaphones for immediate use, and will fab up a mount and connections for the Flowmasters when there's time.

Not sure if you've already considered. But if going with megaphones, have you considered using Supertrapps, to provide adjustable noise reduction via removable/stackable plates.

http://www.supertrapp.com/product_sections/cat.asp?CatID=32

http://www.supertrapp.com/images/product_sections/32.jpg

They also sell adapters for the plates only.

I had one of these on my 240Z racer. Bolted plates on for ride to & from the track. The number of plates used can affect the dB's.

[Jase007]

We've used phase 9 mufflers with great success where noise is a factor (Lime Rock Park).

http://quiethorsepower.com/mufflers.html

And Coast Fabrication mufflers:

http://forums.pelicanparts.com/uploads18/P10009751283534949.jpg

Pelican for sale thread from 9/3/10 (http://forums.pelicanparts.com/porsche-911-used-parts-sale-wanted/562421-fs-custom-race-mufflers-new-coast-fabrication.html)

http://www.coastfab.com/mufflers.html

[Eric S]

We've used phase 9 mufflers with great success where noise is a factor (Lime Rock Park).

Eddie Murphy used a banana...

[good hands]

I've got the supertrapps and they work well.

[Jase007]

Eddie Murphy used a banana...

yes he did ...

[Eric S]

yes he did ...

YouTube - Banana in the tailpipe