Is bending header pipes risky?

[ironhelix]

I have a 6 into 2 header (Nismo Competition, I believe) that actually pressed against the tunnel wall by the gas pedal when I installed the engine. I hammered the tunnel wall sheetmetal enough to get some clearance, but the header still moves enough to rattle more than occasionally. This is unacceptable.

Has anyone tried to bend header pipes to provide more clearance? Half an inch would be adequate. Am I asking for problems? The header is well built otherwise, with a 3/8" flange. I could also pull the header over with a strap, but that's my 2nd choice.

[johnc]

Try replacing your engine and transmission mounts. You can also cut the corner of the floor pan and weld in a new section. Evenly bending that many pipes is difficult. You stand a good chance of kinking one.

 

Another option is an engine limiting strap. Goes on the passenger side and pulls down from the engine mount bracket to the crossmember. If its a nylon strap it won't transmit any noise.

[Tony D]

Agreed:

Mounts, Bigger Hammer, limit strut/chain/strap/link

[Six_Shooter]

In extreme cases, many people have cut headers and added bends/tubing to clear different items.

[luseboy]

Isn't this a common problem with the comp headers? The one Z I've ridden in was a 260z owned by a guy named Leon on here who has comp headers and his hit the tunnel every once in a while. It wasn't that noticeable in his car. I'd say leave the header alone (it's worth quite a bit) and cut out the corner of the floorpan as John suggested. If you replace your engine mounts, consider getting some poly ones from mckinney motorsports which will further prevent your engine from moving.

[ironhelix]

Thanks, all, for your comments. My response was delayed because I decided to have a local shop look at the problem. The problem was not the header (~3/8" clearance), but contact with both the trans mount and diff housing. The motor, trans, and diff mounts have only a few thousand miles on them and look solid.

To solve the problem, he bent a new 2 1/2" exhaust system, installed new hangers, a 24"-long resonator, and reused my DynoMax Super Turbo muffler in the back. What a difference. No more rattles, and no more resonance at 1800-2k RPM! I'm very pleased. I also had an O2 bung installed in the wye-pipe for an aftermarket FI system still in the research phase. I attached a couple of before & after pics.

Edited April 20, 2012 by ironhelix

[Cannonball89]

Looks like the exhaust shop lowered the exhaust system quite a bit underneath the differential compared to what it was at with the old system. I hope you don't drag.

 

In Maryland the curbs in neighborhoods are required to be 12" above the main road level, so I had a hard time getting my 3" exhaust to fit without dragging when turning into my driveway, but the exhaust right now is hugging the differential pretty tight, and that is the only way to prevent it from dragging. I know you have a 2.5" system, but still that sag below the differential is reason for concern for me.

 

On a side note, you have an excellent header, why not let people hear it? The only thing I liked better about my car when it had an L24, SU carbs, and header than I do now with my L28ET was the sounds it made! That chambered muffler in combination with the resonator is surely killing all of those Uber-sexy sound waves! Just my opinion, but an uncorked L6 is a sexy beast.

[ironhelix]

Actually, the lowest point is about same with 5" of ground clearance. It does look worse in the photo. I planned to replace the Eibach springs with Euro Stage 1 springs that I've had for years, but they would have raised the car 1-1 1/2”, so that’s not going to happen. The springs are still sitting on a shelf. 🙂

Edited January 15, 2022 by ironhelix
Facts