Bushwack Posted February 4, 2012 Share Posted February 4, 2012 Just putting it out there as a FWIW... On my last two Reatta purchases, I changed the mufflers and catalytic converters. Did the mufflers first, drove each car for a bit and then changed the cats. Once the cats were changed, each car's performance improved significantly - as in vroom! Installed, each cat cost about $325.00 (L.A. price - your cost will definitely be less). Today, I've driven one of the cars 157 miles (L.A. to Palm Springs/Rancho Mirage - all highway & averaged 58MPH). I will be driving back home tomorrow (130 miles). I'll calculate my gas usage and see if a new cat gives better mpg then typical.So if you feel your Reatta is lethargic, a new cat might be the answer. Link to comment Share on other sites More sharing options...
Guest gigitwo Posted February 4, 2012 Share Posted February 4, 2012 Was your cat a stock replacement or a performance magna flo type? Link to comment Share on other sites More sharing options...
wws944 Posted February 4, 2012 Share Posted February 4, 2012 I would think the stock Reatta muffler, with its twin 2" outlets, is pretty free flowing as is. Has anyone ever cut one open to look at the pipe configuration?Also, the Olds Trofeo had a similar twin outlet pipe configuration. However it was more like the period Camaro/Firebird - with an outlet pipe on each end. Link to comment Share on other sites More sharing options...
Bushwack Posted February 4, 2012 Author Share Posted February 4, 2012 Was your cat a stock replacement or a performance magna flo type?I don't know the manufacturer. Just told the mechanic to change the cat. As he knows me well, he probably went as close to stock as possible (for both cat and muffler). Link to comment Share on other sites More sharing options...
NCReatta Posted February 4, 2012 Share Posted February 4, 2012 Had my cat replaced (against my wishes) for $250 out here. Last tank of gas I took two day trips. Both averaging about 60 mph. Gas milage around 22 mpg. Link to comment Share on other sites More sharing options...
Guest Recian Posted February 4, 2012 Share Posted February 4, 2012 i'd like to do something with my cat as in removal ;) but muffler shops cant legally weld in a pipe in it's place and it's so rusty it wont slide off 6" from the cat like it's supposed to so i can get into it to gut it. I'll have to do some fancy thinking. Im sure that restriction is hindering a few MPG Link to comment Share on other sites More sharing options...
NCReatta Posted February 4, 2012 Share Posted February 4, 2012 i'd like to do something with my cat as in removal ;) but muffler shops cant legally weld in a pipe in it's place and it's so rusty it wont slide off 6" from the cat like it's supposed to so i can get into it to gut it. I'll have to do some fancy thinking. Im sure that restriction is hindering a few MPGI had mine removed for a few months. But I was informed that while NC doesn't check the emissions on cars older than '96, they do require that all emissions components be there and appear to be working. :mad:While it was off the highway milage was about the same, but city has dropped now. Link to comment Share on other sites More sharing options...
Guest groingo Posted February 4, 2012 Share Posted February 4, 2012 Replaced mine a couple weeks ago with a Magna Flow (easy bolt on replacement and only $105.00), performance was improved a bit but mileage dropped from 26 mixed to 22 after three refills which sucks while on examination of the old cat which looked excellent so I chalk that one up to "Preventative Maintenance" and will include the old cat when I sell the car....may be worth more than the car by then! Link to comment Share on other sites More sharing options...
D-a-n-i-e-l Posted February 4, 2012 Share Posted February 4, 2012 Yes the cat is restrictive, but in my experience mpg is a lot better with it on. Like 5 mpg better. I believe this is bc the cat slows down the exhaust so the o2 can get a better reading. If the exhaust is not held for a second then the o2 sensor will see less oxygen in the fuel causing the eclipse to throw more into the engine. Also any power gains a very minimal as the choke point in these cars(stock) is the intake. If you want these cars to have a large amount of gain spend the 2000 and drop in a supercharged motor. Link to comment Share on other sites More sharing options...
Guest spiering.lucas Posted February 4, 2012 Share Posted February 4, 2012 AGREED^^^^^ Link to comment Share on other sites More sharing options...
KDirk Posted February 4, 2012 Share Posted February 4, 2012 I too am coming around to the idea that the cat improves mileage. My 91 has never gotten the MPG's it should, and while I have been known to wear lead soled shoes, even more judicious driving habits have not yielded much improvement. The 91 has a straight pipe in place of the cat; I purchased it that way. I have yet to put a cat back on it due to the cost, and the fact that no one has raised an issue about it in inspection. All that said, what Daniel has stated actually makes sense, so I may end up putting one back in at some point. Since I have been over everything else that would/could impact fuel economy, I have to think this is probably the only thing left that can account for my somewhat poor mileage.The 88 has it's original factory cat, but also does not get the expected MPG's. While it runs well and is not perceptibly sluggish, I wonder if it is partially obstructed due to the period of time when it was running poor with incomplete combustion and incorrect firing order (mis-routed plug wires). So, I guess I need to check that one too. KDirk Link to comment Share on other sites More sharing options...
Guest steveskyhawk Posted February 4, 2012 Share Posted February 4, 2012 Kevin and all,Replacing the cat may satisfy an environmental goal but I hesitate to think it will improve gas mileage. I have 3 1991s, 3 1990s and 1 1989 and the early models will always do better on gas than the 91s. Bear in mind that all my cars are all smog legal with functional cats. It is a known fact that the 1991 has slightly more horsepower and a lower ratio final drive. This combination provides a smoother, slightly more powerful car that burns more gas than the earlier models. There is no free lunch. The difference in early cars vs 91 models is obvious in rpm required at equivalent speeds. The 91 will turn about 300 rpm faster at 70mph. I have also had my proms reprogrammed to delay lockup which yields a smoother driving car but compromises mileage slightly. I personally don't care. I like smooth. Link to comment Share on other sites More sharing options...
KDirk Posted February 4, 2012 Share Posted February 4, 2012 Steve,You are correct of course with regard to the 91 avg MPG vs. the other three years. That said, neither of mine is getting what I consider to be "correct" avg MPG compared to what others who have posted here are getting. Both of mine run mid 14's to low 15's most of the time. I think I should be at least 2-2.5 MPG's higher than that on average. The one thing I have not checked for on the 88 is leaky injectors. At under 40,000 miles I am not sure that would be a problem, but they are 24 years old. I will not be rushing into replacing the cat on either car, but the thought has crossed my mind before that the change in exhaust back pressure is throwing off the ECM thereby affecting the fuel delivery and in turn mileage. The only other issue in play is the fuel itslef. Will not rehash the whole ethanol thing, but I know that is dinging me on my fuel economy somewhat also. KDirk Link to comment Share on other sites More sharing options...
padgett Posted February 5, 2012 Share Posted February 5, 2012 Is that from the CRT or from actual measurement ? Reason I ask is that one of the things the ANCX PROM for the 88 fixed was improper/low MPG readings. Link to comment Share on other sites More sharing options...
KDirk Posted February 5, 2012 Share Posted February 5, 2012 Padgett,on the 88, that is direct from CRT readout. Today it was at 14.7 MPG. I have an ANCX PROM in the ECM (burned from a ROM image you sent me - thank you again!). So, I have no reason to doubt that figure. On the 91, it is from calculating miles traveled divided by number of gallons pumped when refueling. I have calculated over the past few tanks 14.3 to 14.6 MPG. My DeVille gets about that kind of MPG in typical mixed use (city/highway), and it is a lot heavier and has a big V8 in it, so I just can't help thinking there is something amiss. The only obvious issue on the 91 is the lack of a cat in the exhaust.On the 88, the only things I have not checked are the condition of the cat (but have no real reason other than MPG's to suspect it is bad) and whether the injectors are leaky. It runs great, and has good acceleration, but drinks more gas than I think it should.Both have had full tuneups (plugs, wires, stat, O2 sensor, fluids are all good, 88 had a Delco ignition installed) in the not too distant past and tires are kept around 32 -35 lbs.KDirk Link to comment Share on other sites More sharing options...
Bushwack Posted February 5, 2012 Author Share Posted February 5, 2012 Just putting it out there as a FWIW... On my last two Reatta purchases, I changed the mufflers and catalytic converters. Did the mufflers first, drove each car for a bit and then changed the cats. Once the cats were changed, each car's performance improved significantly - as in vroom! Installed, each cat cost about $325.00 (L.A. price - your cost will definitely be less). Today, I've driven one of the cars 157 miles (L.A. to Palm Springs/Rancho Mirage - all highway & averaged 58MPH). I will be driving back home tomorrow (130 miles). I'll calculate my gas usage and see if a new cat gives better mpg then typical.So if you feel your Reatta is lethargic, a new cat might be the answer.Quoting myself for a follow up...Traveled a total of 291 highway miles averaging 63MPH resulting in 27.2MPG (used 10.7 gallons). That's about on the low end for a typical trip but the extra vroom in the car was nice. I usually get 27MPG when averaging 70MPH. So for now, a new cat & muffler seems to made a minor difference in my mpg. But one trip isn't enough for a fair evaluation. Nevertheless, the added performance certainly outweighs a minor drop in fuel economy. With the new Monroe shocks/struts installed on all for corners (and new tires), freeway driving doesn't help much evaluating the shocks. But I will say the car seems much stiffer then my other Reattas (as expected) when driving the freeway over the Botts Dots or when there is a slight dip on the freeway. Once I get a few (or more) miles of city and canyon driving done, I'll know better. Link to comment Share on other sites More sharing options...
handmedownreatta Posted February 5, 2012 Share Posted February 5, 2012 maybe changing to a heated oxygen sensor will help.some camaro people do that when they run headers. Link to comment Share on other sites More sharing options...
padgett Posted February 5, 2012 Share Posted February 5, 2012 Highest I have seen over at least 100 miles was 27 mpg with the 88. Suspect 90 gets better but have no data. The decent highway, bad town MPG makes me wonder if there is a leaky injector involved.BTW the new arrival weighs 4400 lbs, has a 3.6 engine and seems to be getting about 1 mpg better around town than the Reatta. Somewhat surprised but 20 years newer technology. Link to comment Share on other sites More sharing options...
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