Hey everyone, Other than the polluting-mother-earth stuff, what are the downsides of hallowed out catalytic converters? A buddy of mine asked last night and I didn't know. Thanks!
LOL so true, but how about from a tuning perspective? Particularly the O2 Sensor -> ECU -> Fuel system loop?
You can make bypass pipes for <$100... Now you can ignore your "slow down light" too . That thing never seems to work... I wouldn't hollow out the originals... those things are expensive, and as the value of the cars rise, you will need those. Ferrari dealers in our area will not sell a car with the cats removed/hollowed... FYI
+1 -- hollowing out an intact cat is a $ mistake IMO (but, if the cat matrix is already melted/broken, it's no sin ). The (minor) downside to a hollowed out cat structure is that the exhaust gas flow goes thru a needless expansion and compression (both processes have small associated losses -- but are still much less than the flow losses thru an intact cat).
As long as the O2 sensors are still in play, the ECU will correct.....no harm to engine. The bummer is, we have 4 cats (2 precats and 2 regular). What effect would swapping out the 2 rear cats with bypass pipes (with O2 bungs) have. Better sound and or performance? Serious question. A full exhaust swap is around $8,500 (Capristio $5k, Precat delete $3K, Cat delete pipes $500). I would like to do it in stages.
Surely louder sound, and maybe a few HP gain, but it would be better IMO to do the precat bypass first and leave the regular cats in place (better to get "hot" cats further away from the powerplant). Are you sure that your precats are still actually intact?
Hi, I hope this isn`t going off the subject too much - but why is there such a small difference in factory claimed power between say an 86 euro car made without the cats versus a same year US spec car with all the cats? I `ve always thought it said 390 BHP for euro and 380 BHP U.S. spec - which seems hardly any difference considering. I know they`re not Corvette`s but an 80`s Corvette with a relatively low tuned engine and 80`s technology cats makes a good 20 bhp difference with them removed - and that`s just on a 250 BHP car. Wouldn`t it affect a 4.9 390 BHP engine more than a lazy 5.7 250 BHP engine? I would honestly have expected it to have made a 40-50 BHP difference on the Testarossa engine. I don`t claim to know how it all works, which is why I`m asking! Cheers Dom.
Testarossa doesnt have a check engine light as far as I know. It has a "slow down" light, that is set off by high catalytic converter temps... If that was going off and your cat was off, your ecu is wonkers... Bo
I've done my exhaust job in three stages over a year: Step 1: hollowing melted pre-cats, replaced cats with high-flow cats, OEM muffler = slightly louder sound, noticeable and nice, but nothing out of this world Step 2: step 1+replaced the OEM muffler with a stainless steel Nouvalari exhaust = UNBELIEVABLE difference!! The car became more responsive and the sound intoxicating! Only down side, the engine was "singing" great through the revs but past 4500rpm the sound was going away... I always wondered whether it was the expension/compression taking place in the empty pre-cats cavities... Step 3: step 2+replaced the hollow pre-cats with Ferrari OEM pre-cat bypass pipes (part number 142066 and 142067), thinking that it can't hurt and it might make the car sing all the way through the revs= well, it sings all the way to the red line! It also made the sound a little brighter, sharper. These were my observations s far. I do want to try to bypass the high-flow cats to see what happens. I wonder whether it's going to make much of a difference as the flow is probably rather good. I'll try. Yes, by the way, no check engine light on TRs, so no problems. I hope this helps.
Thanks for the info everyone! Have any of you ran your engine with just the collector pipes on (basically straight headers)? Back in my youth one of the sides of my exhaust fell off (hey I was 17 and repaired my Mustang with bailing wire and bubble gum!). I had just the header on the passenger side remaining and WHOA it shook the floor boards!
Ferrari exhaust is fairly well tuned and you don't get much of a power upgrade by replacing it. In fact, some will argue that you get less power when modifying the exhaust. Running open headers will only make it sound like you're going faster.
From a performance perspective get rid of the precats. They are a terrible design and their flow is terrible. The mains aren't great either. I really do hate to advocate their products because they do not stand behind them and their cats are lousy but Hyperflow makes great cat eliminator pipes for the TR.
Imo 512TR/M have these lights ....or wired .... I dunno if TR also ... ? But with straight pipes, I always had Slow Down's ... (sorry, was wrongly named by me) ...
