exhaust questions

[bign_bloatd_merc]

Looking for a good cat back for my '03 mounty with 4.6. Kinda new to forum but didn't find a whole lot searching. Any help would be cool... links and part #'S EVEN BETTER. Thanks

[jah81592]

I recommend MAC or Gibson.
www.hensonperformance.com

[CALDWELL]

search

MAC - GIBSON - FLOWMASTER - MAGNAFLOW

for top results bro...


Danny

[bign_bloatd_merc]

I lost 2-3 mpg's when i put on the K&N intake. I wonder if i have too much oxygen in exhaust manifold telling computer to add more fuel. is there an aftermarket o2 sensor or do i just need a custom tune

[shadowless127]

Originally Posted by bign_bloatd_merc

I lost 2-3 mpg's when i put on the K&N intake. I wonder if i have too much oxygen in exhaust manifold telling computer to add more fuel. is there an aftermarket o2 sensor or do i just need a custom tune

u shouldnt need anything.

I have a feeling your driving more aggresively. Did you unhook the negative terminal on the batter while you were installing it, or after you installed it? This will allow the computer to re-learn the air/fuel curve now that there's more air coming in.

And as far as exhausts, if you just want a complete cat back setup I suggest the Gibson because IMO the magnaflow sounds kind of wimpy.

[turbo cat]

dynomax race bullet (s) for rumble

magnaflow or hooker max flow for mild tone

all 3 of these are strait thru mufflers which help keep the velocity up

a basic baffled muffler will decompress gases to recompres the gases to exit the muffler again. this and the effect the baffles have is killing velocity. This is why tests have shown over and over again that a strait thru muffler will gain both torque and power over baffled mufflers if sized correctly

[shadowless127]

Originally Posted by turbo cat

dynomax race bullet (s) for rumble

magnaflow or hooker max flow for mild tone

all 3 of these are strait thru mufflers which help keep the velocity up

a basic baffled muffler will decompress gases to recompres the gases to exit the muffler again. this and the effect the baffles have is killing velocity. This is why tests have shown over and over again that a strait thru muffler will gain both torque and power over baffled mufflers if sized correctly

this is true but not in all applications. If you're using the stock pipes you really won't see a difference between a straight through and let's say a delta flow. Once you start going with bigger pipes you're better of w/ a straight through.

[Sams01XplrSprt]

welcome i personally like flowmasters cause i got them on my 01 sport and i love them

[turbo cat]

Originally Posted by shadowless127

this is true but not in all applications. If you're using the stock pipes you really won't see a difference between a straight through and let's say a delta flow. Once you start going with bigger pipes you're better of w/ a straight through.

it all depends on the sizing. A bigger pipe will slow velocity down but have low backpressure which is good for high power but will kill torque due to the low velocity at low rpms. A smaller pipe is reverse of that it will have more backpressure which is not good but a higher velocity that helps low end torque but chokes the motor out more wit hhigher backpressure at higher revs. Also as gases cool they expand. When they enter a muffler with large chambers they expand alot and this cools the gas even further then like i said the gases have to recompress to exit the muffler. They have done test after test after test a strait thru setup will gain over a baffled muffler

[bign_bloatd_merc]

Originally Posted by shadowless127

u shouldnt need anything.

I have a feeling your driving more aggresively. Did you unhook the negative terminal on the batter while you were installing it, or after you installed it? This will allow the computer to re-learn the air/fuel curve now that there's more air coming in.

And as far as exhausts, if you just want a complete cat back setup I suggest the Gibson because IMO the magnaflow sounds kind of wimpy.

I UNHOOKED THE NEGATIVE CABLE ON THE BATTERY for 3 hours. I then took it for a drive (mostly interstate highway) for 100 miles. Yes, I actually had somewhere to go. The little MPG computer said I averaged 15.8 mpg. This was mostly higway. I used to get 18-19. everyone tells me the K&N CAI will actaully increase mileage under normal driving but i lost. I don't know what else it could be. 3 months ago I changed to spark plugs. I went with autolite Double platinum. I had one blow out. (apparently this is a common ford problem). The Ford Garage heliocoiled it and put a OEM sparkpulg (about $9.00) in that cylinder and replaced the coil which blew apart ($108). Could i have lost some compression in this cylinder and have unburnt fuel? If so Would it throw an error code and check engine light??

Iowa has 10% ethanol blended fuel for its 89 octane. It's the cheapest. I stopped using it and went back to 87 octane cuz a friend said he got better mileage with it. I'm gonna be driving about 2100 miles around xmas and i'm just looking for ways to get the best mileage. What about the fuel catalyst thing?

[shadowless127]

Originally Posted by bign_bloatd_merc

I UNHOOKED THE NEGATIVE CABLE ON THE BATTERY for 3 hours. I then took it for a drive (mostly interstate highway) for 100 miles. Yes, I actually had somewhere to go. The little MPG computer said I averaged 15.8 mpg. This was mostly higway. I used to get 18-19. everyone tells me the K&N CAI will actaully increase mileage under normal driving but i lost. I don't know what else it could be. 3 months ago I changed to spark plugs. I went with autolite Double platinum. I had one blow out. (apparently this is a common ford problem). The Ford Garage heliocoiled it and put a OEM sparkpulg (about $9.00) in that cylinder and replaced the coil which blew apart ($108). Could i have lost some compression in this cylinder and have unburnt fuel? If so Would it throw an error code and check engine light??

Iowa has 10% ethanol blended fuel for its 89 octane. It's the cheapest. I stopped using it and went back to 87 octane cuz a friend said he got better mileage with it. I'm gonna be driving about 2100 miles around xmas and i'm just looking for ways to get the best mileage. What about the fuel catalyst thing?

That's horrible. I get like 18-19mpg hwy doing about 70-75mph using 87 octane completely stock.

Something doesn't add up here. Instead of using the computer, next time u fill up, reset your trip computer and do it the old fashioned way.... Miles travelled divided gallons used.

[macknos94]

i was getting about 11mpg i was thinking it was because of the tires, intake, exhaust and my driving but that really is horrible. did the seafoam thing and it brought it up too 15 thats the most i can pull out. if you have higher miles give seafoam a try.

[turbo cat]

what gear ratio did your 03 come with? and excess wieght your dragging around? Tire size? Fully loaded options? Oh and i hate platinum plugs i stick to copper cored plugs. Platinums suck in my 02 they just use them becasue they last longer so you can be lazy and not change them. The coppers cost half the price a platinum will so its nto a cost saving thing. As far as the helicoil deal run a compression test to see if you lost any compression somewhere. Also the stock cams on 4.6L engines have a few degrees opf tolerance and this is why some 4.6Ls are monsters over others from the factory

[shadowless127]

Originally Posted by turbo cat

what gear ratio did your 03 come with? and excess wieght your dragging around? Tire size? Fully loaded options? Oh and i hate platinum plugs i stick to copper cored plugs. Platinums suck in my 02 they just use them becasue they last longer so you can be lazy and not change them. The coppers cost half the price a platinum will so its nto a cost saving thing. As far as the helicoil deal run a compression test to see if you lost any compression somewhere. Also the stock cams on 4.6L engines have a few degrees opf tolerance and this is why some 4.6Ls are monsters over others from the factory

I carry around lots of weight, run 245/65's and have fully loaded options and still dont get THAT crap mileage.

[bign_bloatd_merc]

How would i find what gear ratio I got?

And I put the seafoam into this tank of gas so we'll see if it helps.

[shadowless127]

Originally Posted by bign_bloatd_merc

How would i find what gear ratio I got?

And I put the seafoam into this tank of gas so we'll see if it helps.

simple way.

If you have the class III/IV hitch w/the 7-pin socket you have 3.73's, if you have the Class II hitch w/o the 7-pin socket then you have 3.55's.

[guitarfrk741]

hah you think you get bad mileage..
try running 33's on a 3.55 mounty..
id prob say i get around 10mpg combined city/hwy

[shadowless127]

Originally Posted by guitarfrk741

hah you think you get bad mileage..
try running 33's on a 3.55 mounty..
id prob say i get around 10mpg combined city/hwy

my personal opinion, I think you'd get much better MPG's if you had the V8.

[1_v8_merc]

You simply cant go wrong with flowmasters!

I got Flowmaster 40 on my 4.6L v8 Mounty, and it sounds badass, i get looks all the time,lol.

They sound badass on the v6's too, almost the same as the v8.
The v8's just going to have a deeper rumble to it. They both sound good.

They also make the Flowmaster 50 series, alittle more tamed, and the 50 series SUV??
( i swear i saw an SUV series in the flowmaster catalog.)

[macknos94]

I have about a 300lbs system in the back plus all my deployment gear so about 450lbs +. 265/70-17 intake, 40 series flowmaster( sounds awsome) 2.5 piping and only 3 bends all the way back. that's why I figured I get crappy gas milage but the motor did need a tune up