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results from cat change to hiflow cat


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I am on the way to the power I am looking for. I put on a MagnaFlow cat yesterday and the results are amazing. Before the change I was getting 30 mpg on trips to and from my 2nd home in Brainerd. I have made 2 trips the last 2 days. There has been 0 wind and the temps have been in the 30s. I have driven a total of 600 miles and averaged 38 mpg. Not winded aided!!. aAlso regarding added power, I have 245 17s which are a huge tire for the car and from a shanding start can leave a nice rubber trail. Before the change i couldnt get a squeek. I also , as previously mentioned added a K&N cold air cone intake.

I am going to pull the muffler and see how loud a staight pipe off the cat is.

I do expect even more power. i might just end up with a hiflow muffler though. My current choice would have to be Magnaflow .

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Although its not cool with people behind you, i find that I get the best mileage when I drive 76km/h in the city (low low RPM and overdrive stays in) and 96km/h on the highway. City cruising stays near to 7-8litre/100km, and highway 6-7 litres/100km, some times 5 but i think that downhill has a little to do with that. Today I added a little more air to the tires cuz of it being colder and gas is up. I liked the pressure they were at before (34+psi), the routine at the gas station was something similar to doing CPR with the compressor. 6 count for front, 3 count for back. The tires are 215 LEMANS. I got 8/100km today doing 50km/h.

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a) Hadn't you done a few other things also ? Would be interested to know what the BLM and instantaneous readings are.

B) Ran my Sunbird V-8 for many years with just a cat and no muffler, essentially just a single 2.5" pipe out the back. Was never annoying. Secret is to make sure the pipe extends a little past the bumper.

c) Saw over 40 mpg on the Beltway with the a/c off in a 2001 (SII 3800) LeSabre. (About 10 mile average at cruise controlled 60ish). Dropped to about 32 with a/c on. Two different cars (rentals), so is reasonable.

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The MagnaFlow was iinstalled for a total of $202.50. The Magna Flow number is 800-990-0905. Regarding the cone filter., remove the top 1/2 of the air cleaner housing and use leave the bottom 1/2 in and that will be the sorce of the cold/forced air. I bought a cone filter and attachment that is made for Hondas at a place called The Auto Zone an (auto parts chain store). The filter and the install kit are two seperate items and are 25% of the price as a K&N install kit. I then cut down the chrome tube that was the Honda airflow tube so the air cone fit pointed down at the inflow duct of the air cleaner and used the Reatta rubber air tube to make the connection match up. To hold the filter down in the case I just took a very large hose clamp around the rear output of the cone where the tube is installed and also put in very stiff foil on the engine side of the filter around it for a heat shield. I put and molded the foil in before I put on the clamp to keep it in place. Just an FYI, just adding the cone filter didnt do the job since it didn't have access to cold/forced air. I got that effect only after modifying the lower 1/2 of the original filter housing. Took it out for a ride after the mod. and got the car up to normal operating temp on the highway, checked the intake after and it was ice cold. MISSION ACCOMPLISHED. Sorry I have no photo scanner so can't get a pic at present.

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I did put in a new fuel regulator, the cold air intake, platinum plugs and premium wires. would it do any good to change the ignition? let me know

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Well, a Jacobs coill would not hurt but yours is running so well that I don't know if would be any improvement.

Suspect that a very big variable is the O2 sensor. Have heard that the GM ones leave a lot to be desired . All I can tell ifrom the Delco site is that our cars use an AFS-20 sensor and the 2002 LeSabre uses an AFS-109. Wonder if the 109 is a three wire ?

Am also certain that GM would bias the tolerances to the rich side (not so much as to create excess HC) partly because catalysts work better that way and because running excessively lean can be dangerous.

Problem is that it would take a dyno and a good exhaust gas analyzer (easiest on a car with no cat) to even set up properly for testing.

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All I can say is sh*t, sh*t and sh*t.

I can not get over 27 US MPG

Timing chain 2 years old

New AC Delco Rapidfire #14s 60 thos

New MSD Spark Plug Cables

New Jacobs Ultra Coil Pack

New Bosch Premium Oxygen Sensor 12014

RedLine Fuel injector cleaner used every fill

New paper air filter CAI on way.

Synthetic oil

74 MPH on Cruise and all I can get is 27MPG SH*T!!! and I am taking it really easy trying for as much as I can.

stock cat.

MNREATTAGUY;

Some of your extra power will be as a result of the cold air being denser and richer in oxygen. KR will also be lower and coolant will be cooler closer to ideal temperatures.

Similarly the cold tires in the cold weather on the cold road will not stick as well as during the summer heat. This could also account for some of your perceived increased performance.

MPG increase appears to be real SH*T why can't I match or come near.

Do you recall the ID and OD of the cat and how may cubic inches will it flow?

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As previously mentioned the cat is a MagnaFlow. Other than with that difference between the 2 cars along with the cold air intake that is also in my Reatta, I dont know why you can't get any more than 27mpg. How many RPMs does your car turn at 74mph? Mine turns 2,000-2,100 at 80mh and about 1,700 at 74mpg. That figure was impacted more by the cat change than anything else. Check padgetts recent post, he agrees that those numbers see resonable. Also, I can tell you that my 90 Reatta with 33,000 miles on it is in truely remarkable condition. The cat installer used the term flawless for the mechanicle parts of the car he examined. smile.gifsmile.gif One more item to note, MagnaFlow stats tell me that their product reduces backpressure and increases airflow by as much as 167% over a single in/dual out OEM muffler. That translates to me increased BHP, cooler operating temps and longer engine life. They also quote an average increase in peak horse power from the OEM products to their's is +19.5 and decrease 0-60 acceleration times an average of -.53 seconds.

Check out [color:\\"blue\\"] www.magnaflow.com for further information. cool.gif

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That would be great. I graduated from Orono High school in 1980 so I know how to find you. Please contact me via my cell phone @218-330-1180 any time. I would really be interested in seeing your cars as well as you seeing mine and getting some photos of it on the sight. Even though I have a 218 area code on my cell, I am in Bloomington about 90% of the time with nothing but time on my hands. My name is Patrick Hagen. Oh, and by the way thanks for the offer, I look forward to it. smile.gifsmile.gif

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You done all that and still only get 27mpg? Hope you didn't spend too much $ on that stuff. Don't know what year you drive but my 88 with 69000 on it is all factory and running at 70 on cc it gets 30/31 and that includes some mountainous driving. My complaint is not having the power I'd like. Might have to try the cat change.

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  • 9 months later...

Well I found out I have zero back pressure since the previous owner gutted the cat. So my exhaust doesn't restrict any, I also have the stock air intake with a k&n filter and well romping and stomping I only get about 16 mpg in the city and on highway miles i'm not sure how much but its between 22-27. and only time I can squal tires is starting from standing on a turn.

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Okay, first off: Tires -- You are running 245? Thats gotta be gaping out the wheel wells! I run 225 and they are barely fitting in there. 2nd, in 30 degrees, I could squeel the tires across a stoplight! In 90 degrees on cold tires I can run half a stoplight, but once warm they stick like glue. Catalic converters dont give that much power. And tire squeel doesnt equal power at all. The Reatta is a torquey car anyway, thats where the tire roll over is coming from. Also, a cold air intake is gonna be cold after running around in 30 degree weather. Bring it down here where its 98 degrees with 100% humidity and see how well it works. If its not out of the engine bay, its not working too well. While the intake may increase noise, the power is minor. I noticed a 2 whp increase when on the dyno and that was with my intake iced down. I love the fact others are looking for power from their reatta, but dont mistake tire squeel and loud intake sucking and good exhuast tunes for power.

P.S. If the MPG are true, then GJ, but everyone knows More Power = Less Economy.

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