Thursday, July 28, 2005 - 04:35 pm, by: Roy Polestico
Hey
Im looking at putting a new exhaust system in my 92 TT.Dont know what to get done, i want more power without being really loud. What do u guys recommend? Im in perth so if anyone knows of any good places that would be great.
Cheers
David Vaughan Tinkerer Soarer GT Limited (4.0L V8) and is300 (3.0L il6)
Thursday, July 28, 2005 - 04:47 pm, by: David Vaughan
I went around several places with the same basic criteria of a bit more power but not actually loud. The result was (on a V8) to remove the four rear mufflers, behind the collector, and replace them with two offset straight-through mufflers from Redback. It met all the criteria. I used a sound meter to verify that there was no difference at all while cruising at 110, and there is no drone, although you can hear it when you poke your foot down. The change in power was just over 8% as I recall, or 12KW at the rear wheels. Replacing the cats will cost a lot and make little difference to flow. It is the rear mufflers that choke the system. However, I am talking about a V8 so see what TT people have to say as well.
Oh, but if you have not done a BFI 3 yet then there is no point in the exhaust. If you will not let the air in, there is not much point in arranging to help it out again. A BFI will add KW by itself and prime the motor for a decent exhaust.
I got my exhaust from Lew and the car went like a shower of the proverbial after I installed it. And I believe that I have his prototype, so what he is making now should be even better! The most fun I ever had while driving was after I installed the pipes on the way to the exhaust shop to get the mufflers welded on, a totally unsilenced TT driving through town, got some 'interesting' looks from the cops...
My TT is running an exhaust that i built myself, its quiet and flows well. Its 3" from the stock dumps, through to a 18" resonator where the cat used to be (you might have to fit a cat in there somewhere as well), to twin 2.5" pipes out through the back and offset/centre glasspacked straight through mufflers with 2.5" tips. Standard style, just bigger pipe sizes and better mufflers, reasonably cheap too.
Wednesday, August 03, 2005 - 11:57 am, by: Roy Polestico
Would a 2.5" cat-back system with a pipe running single down the centre of the car then split at the rear(left and right, like factory) with a couple of stainless steel mufflers and tips make much differnce? or would it be better to have dual 2.5 inch sports exhaust system with 2 hi-flow cats two straight through mufflers and tips? I have been quoted around $1000 for both is this a reasonable price?
Thursday, January 26, 2006 - 03:16 am, by: Stephen J Coff(Coffee)
I am not sure thats exactly right? Someone could correct me though.
The "Y" pipe system. I would expect this to be the least effective of the three and most likely to generate drone. It uses the one pipe to collect and remove waste. This disturbance as the two amounts of air meet/ clash whilst entering the one larger outlet creates pressure drop, turbulence and disturbes the pulses (rhythm). From here there is a slower air speed, thus creating lower performance. This sudden pressure drop and turbulence is what creates the muffled droning sound.
The "X" pipes idea is to bring the pulses of the exhaust flow together and try cancel the pulses out hence smoother air flow. The dual pipes allow for greater total volume flow without compromising to much on low engines speed exhaust flow. This would make it the quietest of the three types of set up and gives a very smooth note.
The "Dual" straight through pipes tend to be similar to the "X" pipe though without the cross over it doesn't cancel the pulses. In turn you should end up with a system that flows just behind the "X" pipe system but with a louder lumpier note.
The biggest problem most have is sticking larger pipe sizes on the cars than required. This causes the pulse widths to widen, air speed to drop and usually results in crap engines performance, higher fuel usage and a loud droning exhaust.
Thursday, January 26, 2006 - 10:37 pm, by: Mark Paddick(Sparks)
A lot will depend on a particular make of engine. Chrysler (small block) V8s love a 3 inch single system with a simple Y. The Y is not the problem it would at first appear as the pulses are separated in time. Doesn't have the 'bite' of a twin but sounds sweet at revs and actually flows better than a twin system with all the right looking bits. Some things, like right angled cross-pipes on twin systems, you would think are bad for flow but if placed in the right spot will actually flow better on a flow bench than a better looking X pipe in the wrong place. A twin system with balance or X pipes in the right place will flow a lot more than the same system without them. This is only important if the thing can rev and in a lot of cases a system that flows better may actually produce less power from the engine, a certain amount of back pressure is a definite requirement and too little can be as bad as too much. For this reason most systems on serious race engines are developed on a dyno rather than flow bench.
Friday, January 27, 2006 - 06:19 pm, by: Mark Paddick(Sparks)
The research I did was mainly on V8s and L16 Datsun engines. Turbo engines are a different story. We did do an L20 turbo motor, the exhaust for it seemed to be "bigger is better". Back pressure issues are totally different with turbos with less being better though I'm told some turbo setups still need a bit of back pressure. For a TT I would guess 3" or even 3.5" from dumps and then a big single or twin 2 to 2.5" system from there back.
Don Bagnall Moderator New Zealand 1991 UZZ30 GT4.0 V8
Friday, January 27, 2006 - 06:43 pm, by: Don Bagnall(Baggs)
Not that it matters, but our 1976 Pontiac TransAm 455ci/4 spd.had 2.25" pipes from the headers back, WITH an "H" pipe, and sounded SWEET!, AND more importantly, had crap-loads of torque (which, you'd expect!) anyway with a BIG ground thumper like that.
Friday, January 27, 2006 - 09:20 pm, by: Don Bagnall(Baggs)
Exactly!.......A lot of folks accuse the "Septics" of making bollocks cars, BUT, having owned inummerable American vehicles in my lifetime, I can only say, that although they may indulge in "Meat & two vege" engineering...........IT LASTS, AND IS BLOODY SOLID!
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