Magnaflow Miracle Cat?!

[rhouse21]

My factory catalytic converter failed about a year ago, so I replaced my entire exhaust system from the manifolds back with the Magnaflow 2.5" system with their high flow cat. While I felt an immediate seat-of-the-pants difference, I did not do GTech run until this morning.

OH MY LORD!!!!!!!!!

0-60: 5.9 sec
1/4 mile: 14.04 sec @ 104 mph
Road HP: 225

My best numbers before the exhaust were 0-60:~7.6 sec & 1/4 mile of ~17 sec.

This 0-60 time is only 0.2 sec slower than a 1997 Z-28, but the 1/4 mile is actually faster (14.2 sec @ 100mph)!!!

Other than a Z-28 intake and K&N filter, the engine is completely stock. I am amazed!

Has anyone else seen similar results? I haven't performed a dyno run, but these numbers imply a 50-70 HP improvement over stock. I can only imagine what would happen after a good engine tune.

[Need4Camaro]

Re: Magnaflow Miracle Cat?!

Im not trying to bash ya or anything but I would find it extremely difficult to believe you could gain a full second with a full intake / exhaust alone - Would be easy to believe if there was a tune done or maybe a cam added but without that, Im sorry but I can't really buy it. Stock our cars are low to mid 15 seconds and you're knocking on the door of a 13 sec (near LS1 territory) with intake and exhaust alone... Even full intake / exhaust on LS1's although nets them nearly 50 HP (and the difference is exponential the larger the displacement) won't put them in high 11's low 12's as they're mid 13 sec cars stock with the exception of a magnificent few M6's that have dipped into the 12's but those are rare.

Maybe you have a rare car, yeah but intake / exhaust alone isnt going to give you 50 - 70 HP on a stock motor...

[PalmHarborBlkv6]

Re: Magnaflow Miracle Cat?!

I would agree.

[SlasherVRGR]

Times aside, I could see if he had a clogged cat the whole time owning the car and now he doesn't and has a better exhaust, it would seem like night and day. But you throw the times out there and with a badly clogged exhaust you'd be nowhere near 15 sec quarter miles.

Sent from my MB870 using Tapatalk

[rhouse21]

Re: Magnaflow Miracle Cat?!

Ok, I have a correction. My previous best was 0-60: 7.52, 1/4 mile 15.7 sec @88.1 mph.

Trust me, this seems as unlikely to me as it does to you, but I have two runs this morning that are in very close agreement with each other.

I will post screenshots and replays on my YouTube channel shortly and link to them here.

[FIREBIRDV6RAGE]

X3 here

Sent from my SGH-T999 using Tapatalk 2

[rhouse21]

Re: Magnaflow Miracle Cat?!

The video documenting my claim just went live on Youtube. Check it out at the link below.

http://youtu.be/6GtMOqgTMFk

[rhouse21]

Re: Magnaflow Miracle Cat?!

In the interest of full disclosure, I did replace the driveshaft about 10 years ago with a lighter, 1-piece custom unit and I am running Mobile 1 high mileage synthetic oil and Royal Purple gear oil in the diff. Still, that alone should not have gotten me these numbers. I can buy a couple of percentage points from fluids, but there is something going on here beyond what I can rationalize.

I do have a theory, though. The 3800's stock fuel map runs about 10-15% richer than it needs to be to provide extra cylinder cooling and good drivability. One of the first things a good tuner will do is lean out the engine, which increases cylinder pressure, increasing torque and HP. If the engine is breathing substantially better (which should be the case), more air should enter the cylinders, but the stock injectors would not be able to maintain the factory fuel:air ratio, so the mixture should lean out, increasing cylinder pressure and HP in a similar fashion as an actual engine tune.

So, maybe 20 -30 HP came from the intake and exhaust, a handful came from the reduced rotating mass of the lighter drive shaft, another few came from the synthetic fluids, and a few more HP found their way to the party because of the leaning out of the fuel ratio. It was also pretty cool out, so maybe the denser air helped too. Either way, the video clearly shows the GTech data.

I'm just trying to make sense of it.

[bigbrian442]

Re: Magnaflow Miracle Cat?!

I think your G tech is broken. Take it to the track and back up your claims. Capital Raceway is open this week end.

[MegaHertz]

Re: Magnaflow Miracle Cat?!

Having seen the difference a clogged cat makes I can believe you picked up quite a bit of power getting rid of that. I couldn't rev much past 3.5k when my cat got really bad. Still I take g-tech numbers with a grain of salt. I've never owned one or anything similar (maybe I do - there's an app for that), but I view them as a comparative device rather than something that is truly accurate. I've never been to the track either but that does seem like a better tool for getting real data rather than an estimate based on an accelerometer in a little electronic device.

[rhouse21]

Re: Magnaflow Miracle Cat?!

Trust me, I'm not that guy who goes on forums making crazy claims to spin people up. I'm an engineer who observed something strange (and kinda cool) and was seeking out others who might have info to help make sense of the data.

This is my daily driver with over 253,000 miles on it. I am the original owner and have treated her well for 17 years. Because of the mileage and the fact that I cannot have her breaking on me right now, there are no track days in the near future. (Sorry Brian.)

The GTech definitely is not broken and I have another run from the same morning documenting 0-60: 6.15 sec & 1/4 mile: 14.36 sec @100.3 mph.

Look, I'm to old to sit here and lie to you guys. I'm trying to find a dyno shop in the area and will probably get a tune afterwards to see where I can take this. I will keep you guys posted as I learn more.

[ssms5411]

Re: Magnaflow Miracle Cat?!

I wouldn't trust a G-tech for anything only way to know actual times is a dyno or take it to the track, everything else is useless.

[bigbrian442]

Re: Magnaflow Miracle Cat?!

Trust me, I'm not that guy who goes on forums making crazy claims to spin people up. I'm an engineer who observed something strange (and kinda cool) and was seeking out others who might have info to help make sense of the data.

This is my daily driver with over 253,000 miles on it. I am the original owner and have treated her well for 17 years. Because of the mileage and the fact that I cannot have her breaking on me right now, there are no track days in the near future. (Sorry Brian.)

The GTech definitely is not broken and I have another run from the same morning documenting 0-60: 6.15 sec & 1/4 mile: 14.36 sec @100.3 mph.

Look, I'm to old to sit here and lie to you guys. I'm trying to find a dyno shop in the area and will probably get a tune afterwards to see where I can take this. I will keep you guys posted as I learn more.

What is the difference between making a pass at the track or making a pass on the street with the G tech? Or even running its balls off on a dyno?

[insidethreat07]

Re: Magnaflow Miracle Cat?!

What is the difference between making a pass at the track or making a pass on the street with the G tech? Or even running its balls off on a dyno?

Drag strip and GTECH is completely different. I know a guy that used a gtech and it wasn't even close to what is car ran at the strip fwiw

[insidethreat07]

Re: Magnaflow Miracle Cat?!

In the interest of full disclosure, I did replace the driveshaft about 10 years ago with a lighter, 1-piece custom unit and I am running Mobile 1 high mileage synthetic oil and Royal Purple gear oil in the diff. Still, that alone should not have gotten me these numbers. I can buy a couple of percentage points from fluids, but there is something going on here beyond what I can rationalize.

I do have a theory, though. The 3800's stock fuel map runs about 10-15% richer than it needs to be to provide extra cylinder cooling and good drivability. One of the first things a good tuner will do is lean out the engine, which increases cylinder pressure, increasing torque and HP. If the engine is breathing substantially better (which should be the case), more air should enter the cylinders, but the stock injectors would not be able to maintain the factory fuel:air ratio, so the mixture should lean out, increasing cylinder pressure and HP in a similar fashion as an actual engine tune.

So, maybe 20 -30 HP came from the intake and exhaust, a handful came from the reduced rotating mass of the lighter drive shaft, another few came from the synthetic fluids, and a few more HP found their way to the party because of the leaning out of the fuel ratio. It was also pretty cool out, so maybe the denser air helped too. Either way, the video clearly shows the GTech data.

I'm just trying to make sense of it.

I have pacesetter headers, ypipe, and 3'' full exhaust, flowmaster muffler, shaved intake lid, !air silencer, !EGR, !Cat. My best time is 15.410 with drag radials and suspension work. Plus a good tune and I gained around 15 hp which is the norm for a 3.8. I'm just a shade on the rich side to prevent spark knock/detonation. I think your gtech is broken.