Re: TR6 Exhaust system ideas
Hi,
Probably the most common complaint about Monza/Pacesetter systems is that their painted mild steel doesn't last particularly long, tends to rust out pretty quickly. I've also heard a number of them on various cars and they might be a bit louder than some other systems. On the other hand, they are less expensive than most other systems, particularly any stainless steel.
Now, to be fair, mild steel construction is probably adequate for a daily driver where the system is used a lot and very regularly blown clear of any condensation and caustic exhaust gas chemicals. It's far more likely a mild steel system will rot out quickly on a car that's only driven occasionally, sits alot between uses. Of course, driving conditions play a big role, too: ambient humidity, how the car is stored, if salt is used on local roads in Winter or if you are situated near saltwater, etc.
Don't know much about the Ansa system, but have heard good things about it.
For TR6 you should also find Bell and Falcon exhaust systems. I don't know much about Bell, but have heard really good things about it, too. I have used Falcon on other cars (so far, not on TR6).
AFAIK, all Falcon are stainless steel (made in England) and come in two varieties: stock style and sport. In all likelihood, one of these is this is what you'll get if you purchase a stainless steel system from the major U.S. Triumph parts vendors. Most sell the stock style. One or two also offer the sport system, which has slightly larger ID pipes and a freer flowing muffler (perhaps a single muffler instead of a muffler/resonator combo as was original on many TRs), and no doubt will be a bit louder. Most recently I found a Falcon sport system for my TR4 was easy to install, bolted right up to the stock hangers. My one relatively minor gripe is that the exhaust pipes are not mandrel bent, so see a little crushing at each inside radius (OTOH, the Falcon header obviously is mandrel bent and so has nice, smooth bends throughout). The only clearance issue I had was with one of my own frame strengthening modifcations that got a little in the way of the pipe right after the header collector.
Are you planning to install a header? If so, again there are a couple major types. They come with long or short primary tubing, which is one of a the main considerations for header tuning purposes. The shorter type primary headers are cometimes called "Tri-Y" (for a 6-cyl. car) or "6-3-1" since the primaries are first paired into secondary tubes, then three of those gather into the collector. The longer primary type are sometimes called "6-1" and have all six primaries "bundled" and curved to end together the collector.
In a nutshell, long primary headers will give the highest HP at upper rpms, and might be considered "race" headers. This is at the expense of some low to mid range torque. The shorter primary type might be more appropriate for street use, preserving or even improving lower to mid rpm torque.
Of the headers I'm familiar with by brand, Stahl and Pacesetter are long primary type (6-1 and 4-1) and are made of mild steel, and Falcon's stainless steel are short (6-3-1 and 4-2-1). Not sure about Bell and Ansa, but hopefully this gives you a means of comparison.
Of course, headers also come in two materials: stainless and mild steel. Stainless is more durable in high temps and can even be wrapped with insulating "header wrap" to help reduce temperatures under the hood. The wrap also increases scavangeing by keeping heat inside the header, producing higher gas flow speeds which can help the engine "breathe". Mild steel will not hold up under the wrap, so might better be ceramic coated for all the same reasons.
Thanks to their thinner tubing, headers will tend to be noisier than the stock cast manifold (which really isn't a bad performer, by the way). Wrapping or ceramic coating will both help offset this to some degree.
Also, most "hotter" performance mods done in an engine will also increase exhaust noise levels, no matter what manifold and exhaust systems are used.
On the inline 4 cyl. and 6 cyl. TRs a single pipe exhaust system such as you are considering is generally a bit more effective, in terms of torque and HP throughout the rpm range, than is a dual exhaust system. However, not to rain on your parade, but take a close look under the rear of your car and I think you'll find clearance issues with the frame if you try to bring the pipe out the very center "Boxster style". Off to one side or the other there is a bit more room to tuck pipes and muffler up underneath the car.
One thing to be careful about is getting too large piping in an exhaust system. 2, 2.125 or 2.25 ID are about as large a single pipe as a street car can handle, also somewhat dependent upon the general tune of the engine (smaller for more mildly tuned engines, larger for those with a lots of performance upgrades). Larger pipe might increase HP at high rpm, but will tend "gut" low end torque in the process, making the car less fun to drive on the street, in traffic.
Another possibility is to get an exhaust system fabricated locally. More and more shops are bending and welding up excellent stainless steel systems at competitive prices and there is a wider than ever variety of good quality mufflers being made. You might at least get a quote, for comparison, if you are considering stainless steel. There are some added features you might consider when building a system like this. For example, AFAIK, none of the off-the-shelf systems include a flex fitting up near the header. This sort of fitting is a good thing to include if at all possible since it isolates the manifold or header from heavy vibrations and strains that can crack it eventually.
Perhaps some of the best Triumph exhaust systems are being made up by Revington TR in England. You might take a look at those in a catalog or online, even if not considering buying one and having it shipped over. Neil has done a lot of homework on pipe sizes and mufflers. He also uses spring connectors with slip joints and skid plates to help the system survive rough rally driving, all of which can be very helpful on street cars, too.
On any of these systems you can add dual exhaust tips for styling purposes or just simple extensions if you find exhaust fumes are being drawn into the car.
Hope this helps with all your decisions.
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