TR exhaust

The stock exhaust system and the cats are equally restrictive, which is big time. Hyperflows or testpipes will make the car a bit louder and freer flowing. A decent sports exhaust will bring the sound of your car to life compared to the dead quiet noise emmitted from the stock one. The OEM exhaust is very restrictive compared to the sports equivalent. If you take the cats off the stock muffler, the TR will sound very slightly louder inside the car, but it's hardly noticeable- only worth it if you want the car to be that bit faster in both acceleration and topend speed.

 

I have a 512TR which will be comparable to the Testarossa in sound. When I purchased the car I had the cats replaced with test pipes primarily as a safety feature because of numerous fires caused by the cats. I never drove it without the test pipes but there was very little noise from the exhaust with the test pipes.

In a couple months I installed a Tubi. Still not much exhaust noise even under full acceleration.

Next step was to remove the restrictive honeycomb material from the pre-cats. When I removed them from the car I could hardly believe what I saw. The restriction was so great I don't know how the engine ran at all. I built some unique tools to get the material out, which wasn't easy as the chamber cross-section expands much larger than the inlet and outlet pipes. The material removed filled a gallon can half full.

This unleashed the engine so it could breath. At cruising speed of 3000 to 3500 rpm the exhaust noise is hardly audible inside the car and is covered up by wind and road noise. But stand on the throttle at higher rpm and all hell breaks loose. I've yet to have someone else drive the car so I can hear it. But going through a short tunnel under a local railroad track it about loosens the concrete pillars.

I know when I sell the car I'll probably have to replace this stuff if it goes to a rough emission area, but I got it to drive and do drive it a lot. Enjoyment is the issue and I'm not the least bit concerned about the value on down the road which I hope will be a long time.

After the above work I took the car to Dallas to the dealer for balancing the banks and setting the idle mixture. Sometime prior to this I had to replace the oxygen sensors. It is running very strong at the moment.

Ron Judy

 

Hi Ron,

That's very interesting comment on the pre-cats. I've just swapped out the stock cats for Hyperflow, and really didn't notice any difference in sound; and I have a Tubi also. I mean with the current setup, it seems like a gentleman's car - with the windows rolled up, you can easily carry on a nice conversation. My 328 sound better. Maybe I'll have to gut the pre-cat to get it to the level I want.

FWIW, my mechanic told me the 512TR runs really clean, almost to the point of not even needing the cats. The pre-cat were put in to meet the one time strict EPA testing from a manufacture with a new car. After the car is certified, from that one test(I can't recall what it's called), it will never be needed again from what I've been told.

Out of curiosity - what specials tools did you have to use to get the materials out of the pre-cats - or do you have any tips to offer??

Thanks

 

You can actually hollow out your precats with a long masonry drill bit and a lot of wrestling. As I recall it's a bunch of metal looped material kinda like chainmail from the dark ages.....you know that chain-like armor protection that knights used to wear. I know my description sounds stupid but that's the only thing I can think of that is close.

My TR has an old Borla system on it. This system totally does away with precats and cars. It bolts up directly to the headers, each with it's own pipe, muffler, and tail pipe. No cross-over stuff or anything. The muffles are straight thru types with a perforated tube inside so the system has minimal restriction. And at idle and cruise the sound is quite mellow, not loud at all but you can hear it. At wide open throttle it really howls and sounds very menacing! I've been considering changing out the 4 mufflers for straight pipe just to see how it sounds. In my opinion, with four pipes and all the bends and stuff and no mufflers, I still don't think a boxer 12 motor will be terribly loud except at wide open throttle. I bought my system used of ebay and spent MANY hours cleaning and polishing. I'll try to find a pic and post it.
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I started with a long masonry drill bit to get holes through the honeycomb and then a long screwdriver to pry and bend it apart where it would come loose. The hard part was in the expanded out-of-sight corners where the tube is much bigger than the inlet you've working through. The honeycomb is bonded to the pipes very tightly. I built a steel hook out of about 1/4" X 1" strap iron to reach these spots and pull the material out. I ground the bent end to a sharp edge to scrape the walls of the tubing. You must get every bit out or there is the chance it will break loose later and go into the Tubi causing real problems.

I'm leaving for a week very early tomorrow and will check the thread on returning to see if I need to add or clarify anything.

Ron Judy

 

Thanks Jeff & Ron for the info. I think I understand your description. Of course, all of this will make sense when I pull it apart for the first time. I'll keep this on my list of things to do for the car.

Thanks

 

Gene -- You've asked a trick question, because ANY modification is technically illegal, but, in terms of what comes out the tailpipe during warm-running, having gutted or no pre-cats won't make any difference (as long as the regular cats are present). And IME, as long as the regular cats are present, the inspection tech won't even know there are any changes.

Ferrari themselves actually make (or at least made at one time) 2 different sets of "bypass" pipes for other TR versions that fit the US systems -- very long ones that replace both the pre-cats and cats simultaneously and shorter ones that replace the pre-cat only. The jpeg shows the shorter ones replacing the pre-cats only -- I can post the PN later so you can check with Ricambi, Rutlands, etc. to see if they are still available.

I do hate to see working, intact TR pre-cats needlessly destroyed. I've got a gutted 1/6 pre-cat, and if you have intact precats and are going to gut them, please give me a shout and I'd be glad to trade the gutted 1/6 pre-cat + a few hundred $ for an intact 1/6 pre-cat.
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Steve: That's a cool set up using just the cats and nothing else. I was considering that exact arrangement but couldn't figure out a way to shape the pipe from the right side cat exit (left side exhaust tips) and still place the twin tail pipe tips in the correct location, as it's so far towards the rear of the car their doesn't appear to be enough room. Now I see I was wrong and it has been done! Do you have any other pics of that system? Or better yet....another set of tips like those shown?

 

Jeff -- You're mis-interpretting the picture. It's just a standard US Tubi silencer (i.e., headers -to- precat bypass -to- regular cat -to- Tubi silencer)
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Darn.....I was hoping that my idea had some merit. Oh well....too bad...it would make for a very light weight system. I sure would like to hear how it would sound that way. Who knows....I still may try and make something like it. The pipe/tip coming off the cat would have to be like a pig tail and curl around and out the back. Hmmmm......

 

Wow....that system near the top of the page looks like an artistic sculpture!! A maze of pipes....nice!

 

gene -- the F PNs for the "US" TR bypass pipes are:

128589 & 128590 = the long ones that replace both the pre-cat and cat (i.e., header -to- bypass pipe -to- silencer)

142166 & 142167 = the short ones that replace only the pre-cat (i.e., header -to- bypass pipe -to- regular cat -to- silencer)

 

The exhaust that Steve posted looks very interesting.What does it sound like compared to the tubi with test pipes? I made my test pipes out of 304 statinless steel and machined flanges. My 86 doesn't have pre-cats and the tubi came with the car. The 12 cyl. sounds muted compared to the tubi and test pipes on my 348. The TR turns about 2200 rpm at highway speed and is very quiet vs. 3000 rpm for the 348 and has a distinctive almost drone. But to be fair, the 348 sounds like a F1 car at redline. A Flist poster in Seattle passes the emissions test with empty cats. FWIW. Jeff