Horsepower with Warranty

[Gear_Head]

I have a Scottsdale Dual exhaust (catback) system on my turbocharged GT Cruiser. They make a straight through glasspacked mid mounted muffler. They offer a unit optimized for Turbo/Super charged vehicles and a separate system for NA applications. I ordered the medium version. The quiet version has a resonator between the glasspack & the "Y" split for the dual exhausts. The 3" tips are polished, & chromed stainless and are as good looking as ANY that I have seen. This was the 1st mod that I did when I got the vehicle in November 2002. The company is reputable, knowledgable, and responsive. They are a pleasure to do business with. They also stand behind their product 100%. I have called them w/questions and they have been extremely accomodating. The spare tire can be accessed w/out moving the pipes. All of the original mounting points are utilized with a set of high quality bolt on hanger mounts (one for each side) for the dual pipes. They sound great and did yield a performance increase when coupled with the AMX1397 turbo-up intake system. Their web site has pics of the system if you want to take a look. If you are interested in how they look on the cruiser, e-mail me and I'll send you pics of mine. [8D]

Alan

[Kirby]

Question: on the Scottsdale dual system; is it stainless? (Probably not so important where we don't have a real winter), and the bends look like the stock bends that narrow the tube, can't really tell from the pic.
Is the tube Dia 2 1/4" or 2 1/2"?
The price is lower though $425 (do they pay shipping?) as compared with $499 for the BTG.
The nice "Y" pipe will insure you don't have the problem that Borla and the muffler guys have of unequal exhaust.

There are a lot of good quality choices available for the PT. The exhaust system is one of the most enjoyable (love that rumble).

[Dalite]

On the subject of exhaust... I would love to see a simple setup that allowed you to replace the stock muffler with a straight pipe, and a fancy tip that enclosed a tunable iris kind of setup. My idea here is that the straight pipe doesn't result in that much noise increase (on a turbo charged engine), and by "tuning" the amount of backpressure while dynoing performance, we could get an idea if there is an optimim backpressure needed. This also might yield a resolution to the discussion of what happens to low end torque with less backpressure.

This is based on the chain of thought that says an increase in diameter, or a noticable lessening of back pressure within the system allows the gasses from the exhaust to cool more as they travel from engine to tail pipe. As they cool, they become more dense, and have the potential to actually slow extraction. By keeping the same size pipe from front to rear, and "tuning" the back pressure at the exit point, keeping the temperature and gas density as uniform as possible. At that point, larger diameters, smoother bends and other historical performance enhancements would start to yield benefits that are closer to optimim than using the more convention approach which introduces a lot of variables and depends on repeatability.

By repeatability, what I mean here is that mass-manufacturing assures that each exhaust kit made for a specific model will be produced within close tolerances, as designed from data obtained on an "average" test bed. With the tunable tip, the performance could be "tweaked" to provide maximum performance for each individual installation.

By running an relatively unrestricted exhaust system, right up to the last 6 to 8 inches before introducing any density change, we could find out if tuning for individual setups would provide optimium performance gains.

If this worked, someone could design either a "lockable" version that could be permanently set to the optimim adjustment. If the idea has merit, an entire line of tips could be made that would each progressively add more backpressure, so the test could be made wiith the adjustable one, then it's inside opening could be mic'ed and a tip with the approiate inner diameter installed.

I think we can all agree that there is an advantage to exhaust modification on a turbo charged vehicle that is not experienced on non-turbo charged engines, just by virtue of the exhaust system being an extension of the turbo charger. I think Kirby brought a great point here that substantial gains can be appreciated by improving the exhaust system. This way may introduce a more scientific way for the customizer or performance muffler shop to make it "good to the last drop".

Is this a possibility, or a "pipe dream"?

[dsm_mike]

Sorry Dalite, but your idea already exists. It is a muffler made by a company called supertrapp. It comes with a package of diffuser disks. The more disks you add, the lower the backpressure and the louder the tone.Removing disks adds backpressure and quiets down the exhaust. I dont know if or how well this works, but its been around for a while. Check it out here : http://www.supertrappind.com/disc_te...technology.htm

[Dalite]

Oh Well, it was a thought. Apparently someone else was thinking the same.

[flashbk2]

Not to make you feel worse Dalite but "supertrapp" has been around for years for motorcycles,race vehicles ect. They are pricey but effective local stock cars started using them when "mufflers " became required !

[Cal Cruzer]

You know I have never understood their explanation of how their system works. I don't understand how putting more things in the tailpipe REDUCES backpressure. Logic would tell me that the opposite would be true.

[Dalite]

I think that putting more restriction may keep the exhaust heat high enough that it doesn't become more dense due to cooling as it passes through an un-optimized exhaust system. That theory may be flawed, if the exhaust has already cooled and become more dense prior to the muffler. However, it does seem that the advertised reaction is oppisite what you would think it would be.

[flashbk2]

Cal I realize the concept may be unique but they are a company that posted dyno results in their advertisments .

[Ian-PT-GT]

Don't get confused with this system.

It is true that if you add disks, it reduces back presure, but it is because the end disk is a cover and no air will exit thru it. the discs are vented and if you add them you add exhaust ports reducing back pressure. There is no incredible science in this.

You need some high temperatures but it is for the catalitic converter to work efficiently, That it is why it is placed as close as possible to the engine But after 14.6 PSI (this is twice the ambient air) the small turbos we have will generate a lot of heat.

Low restrictions would have a positive effect under high boost conditions, because you are moving a lot of air thru the engine and you need it to get it out. But this is all in combinations. If you get one with to little back pressure, you can get a bigger turbo lag. or it won't spin as fast as it should. My uneducated guess woild be that if you plan to run the car at 14 PSI or higher, you should remove that beer Keg from the system and go with a straight thru or low restriction muffler.

$0.02

Ian