Boosted with cats questions

[Robottrainer]

Goooooood Luck!

MAK PERFORMANCE says rounding the header to match the flange is optional.

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[engineermike]

I mean, I guess you could fill the gap with weld/snot….

 

[Robottrainer]

I mean, I guess you could fill the gap with weld/snot….

Lol! Sure! Shove some spare nuts and bolts in there. Melt them down. A little filling and sandpaper...good to go!

 

[GregO]

And....

Find an expanding tool, expand it at room temp or use a plumbers MAPP gas torch to slightly heat. It's 400 series so it's highly malleable. If it rips weld it shut.

Here’s what at one time was 4” round 304 .065 that I cold formed with my die set. EP grease mandatory.

 

[Robottrainer]

Find an expanding tool, expand it at room temp or use a plumbers MAPP gas torch to slightly heat. It's 400 series so it's highly malleable. If it rips weld it shut.

Here’s what at one time was 4” round 304 .065 that I cold formed with my die set. EP grease mandatory.

I have an expander but I was afraid it would split the outlet. It has to expand at least 1/2" total inches

 

[Robottrainer]

I have an expander but I was afraid it would split the outlet. It has to expand at least 1/2" total inches

This thing appears to be two stamped halves welded together

 

[GregO]

I have an expander but I was afraid it would split the outlet. It has to expand at least 1/2" total inches

This thing appears to be two stamped halves welded together

There's some risk that it will split. I've had that happen when making tee fittings. We'll take a piece of aluminum or copper on the back side of split and weld it shut.
If you use CMD EP grease #3 and expand slowly it might not split. No guarantees though.

 

[Robottrainer]

There's some risk that it will split. I've had that happen when making tee fittings. We'll take a piece of aluminum or copper on the back side of split and weld it shut.
If you use CMD EP grease #3 and expand slowly it might not split. No guarantees though.

I have access to a torch. Since this thing has to expand alot in the middle and just at the end (the O2 bung is very close to the outlet), heat might be safer. I van then hit it with the expander just to fine tune it.

 

[GregO]

I have access to a torch. Since this thing has to expand alot in the middle and just at the end (the O2 bung is very close to the outlet), heat might be safer. I van then hit it with the expander just to fine tune it.

The material is soft it's going to stretch easily. Keep the heat low, you'll be surprise how little heat you'll need.
Good Luck, looking great so far.

 

[Robottrainer]

The material is soft it's going to stretch easily. Keep the heat low, you'll be surprise how little heat you'll need.
Good Luck, looking great so far.

Thanks! I'll more the wiser this afternoon.

The material is soft it's going to stretch easily. Keep the heat low, you'll be surprise how little heat you'll need.
Good Luck, looking great so far.

Well that was interesting. Took us an hour to figure out how to hold it, heat it and beat it. We had to take turns wacking at it. Whatever it's made of, it's tough. You can't really get deep in on it due to the bung. It's mostly the lip.

 

[Robottrainer]

Thanks! I'll more the wiser this afternoon.

Well that was interesting. Took us an hour to figure out how to hold it, heat it and beat it. We had to take turns wacking at it. Whatever it's made of, it's tough. You can't really get deep in on it due to the bung. It's mostly the lip.

Fitting and tack welding. I didn't want to risk tacking it on the car least I blow up the PCM. Fitted it up, marked it, tacked it checked it, had to bend it more, re-tacked it, driver side pipe is slightly low. If worse comes to worse I'll slice the pipe and install a coupler so I can spin it up slightly....we'll see. Off to the tig welder...

 

[engineermike]

Looks better than mine!

 

[Robottrainer]

Looks better than mine!

Thanks! Where it looks good....that's my buddy Dale that runs a racecard fab shop. The driver's side being a bit lower....that's me! In my fault for not tacking it on the car, but I was worried about taking out the PCM or a module. I can always bend it. The instructions they give with those kids should be reference only. Reality has many variables

 

[Robottrainer]

Thanks! Where it looks good....that's my buddy Dale that runs a racecard fab shop. The driver's side being a bit lower....that's me! In my fault for not tacking it on the car, but I was worried about taking out the PCM or a module. I can always bend it. The instructions they give with those kids should be reference only. Reality has many variables

Ready to install!

 

[Robottrainer]

So here is a funny anecdote. Reading the factory service manual on re-installing the header. It says to install the nuts finger tight prior to two stage torquing to 18, then 24 lb.ft. Couple of problems with that. The nuts are lock nuts. Next to impossible to finger tighten. As far as torquing...there is no way to get a torque wrench into 2 sq inches of space. Had to revert to the German standard of gutentite.

Some things to keep in mind if you plan on doing this cat mod using the oem headers. The factory exhaust has the cheesy flex connection. It forgives alot of sins. With the Mak or 2m set up, you have rigid 3" pipe. With all the fabrication involved, it will be most likely be off enough that you will have to do some modding to get the new pipes to align with the x-pipe/H-pipe. I will have pics shortly.

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