I bought two magnaflow high-flow cats for my '97 F150 w/ 4.6.

I actually found someone who is willing to take the 4 out and reinstall the 2 magnaflows. $80 cash.

He said there's a way to weld everything into place without unbolting anything from the manifold, using some sort a wire thing to weld with??? He said he's been doing exhaust for 27 years now.

He can bend the pipe for me but does not do mandrel bent stuff at his shop. He said it will pinch in a little bit at the bends. However, he can order prebent mandrel bent sections.

The angle of new pipe he's going to bend where the "pre-cats" are is a fairly sharp angle.

I do not want the airflow benifits of the highflows to be cancelled out by pipe that may be more restrictive at the bends.



HERE ARE MY 3 QUESTIONS FOR EVERYONE:

Will he defeat the purpose of the high flow cats by bending this pipe himself and the pipe pinching in a little?

Has anyone heard of using some sort of wire to weld all the way around the pipe so it doesn't have to be unbolted at the manifold?

Should I have him order the pre-bent pieces?


Thanks again for your time and advice!

 

I've never heard of a muffler shop that doesn't bend or fab their own pieces of pipe to install on a vehicle,thats why you go there for the "custom"fit.I'm not quite sure what your talking about as far as the "wire" welding.I know they use welding rod and I've seen welders that automatically feed the rod into the work as you weld along.the mecahnic that installed my high flows first positioned the pipe,the new cat and the bung for the factory o2 sensor in position,he then tacked eveything in position,removed the pipe from the exhaust manifold and welded everything up,installed the pipe back on the manifold and completed the install.I don't see how you can weld the pipe coming from the manifold w/o removing it,with the tight space in that area.Have him show you exactly what he's going to do before he starts.Maybe he does have a way to weld thats a little different from the norm.If you think it will work for you,then have him do it.Its very frustrating and aggrevating going from shop to shop to first find someone to do the work and then wondering if there way is the right way,it can be a bit much at times,good luck w/your high flows.

 

If he can not do mandrel bends then I would get him to order the pieces for you! Better safe then sorry. You don't want to mess up the flow with cripes.
About the welding.
If he says he can do it then he has probably done it a 1000 times. Worst thing that could happen is you get a leak. Then just take it back and I'm sure he'll fix it for nothing.

Phil

 

Another thing. Make sure to ask him if he has a welder specifically for stainless steel. No point in ordering a bunch of bends and having him weld it all together only to have your welds rust apart in a couple of years.

I had to call a couple exhaust shops in my area to find one that could weld stainless.

I bought a few sections of stainless pipe along with stainless magnaflow mufflers. What good is all of my stainless stuff if the welds are gonna rust apart on me.

 

check ur email

 

Syoung what mag cats did u order? I'm looking to do EXACTLY what you plan on doing.

Thanks!

 

Here is how I did mine.

 

I got magnaflow 94306

 

I have an idea. Don't know if it will work.....but it may eliminate having to bend pipe that may be inefficient with air flow...

Before I take it to the shop I could cut out my rear cats and then reach into the front cats and knock out the insides of them....

I don't know what the insides look like. Would I be able to get all the debris out so crap's not blowing into my new cats later or is it difficult to remove every bit of the stuff?



Would that akward shaped precat flow air good when it's gutted? I assume it's an open chamber on the inside and not shaped like pipe.

Does Advance or AutoZone sell flexibe pipe that I could easily patch in there to keep it quiet on the way to the shop?

My main goal of gutting the precats instead of removing it is to eliminate extra bending at the shop which may result in less efficient flow. Unless I have him order mandrel bent sections....more$$$$$

Is this a good idea??? I have until Monday to figure this out

 

hmm I doubt you will gut them while they are on the truck. Its only 2 bolts to get them off so you dont chance cracking your manifold. Its just an open chamber. You will be just fine by gutting them and having high flows on the back of that.

 

Thanks for all the help so far. I don't know much about this subject.

But why couldn't I knock the stuff out if I cut the pipe right behind the precats? (Removing the rears until I get to the shop and have highflows installed.

I thought it was easy to do 'cause some people talk about the stuff just crumbling apart.

I do not have a clue, but I thought of taking something with a little bend to it and poking in them and using a vacuum to try and suck stuff out.

You aren't saying I can take out two bolts and remove precats by themselves are you? You're saying 2 bolts to disconnect at the manifold, right?

 

no, 2 bolts to remove the precats. I knocked mine out, and the amount of force it took, i would not do it with them still bolted to the manifold. mine was like solid ceramic, very hard to break apart. I used a sledge, a very large screw driver, and a 2' chissel(sp)

 

thanks for the info built. i learn something new every day

 

Is the pipe bigger on the engine side of the precats than on the back side?

Maybe 3" pipe coming into it and 2.5" going to the main cats?



I ask because I was reading old threads...


Here is an old quote from FasterF150:

"there are 4 cats total 2 pre's they just have a few screens on them their mostly for size transition to the smaller exhaust pipe and to make the bend."

 

the guy i had do my exhaust couldnt unbolt the exhaust from the manifold, so instead he welded to it using a wirefeed.

maybe thats what you were being told about?