The 24 Hours of Lemons Forums → Lemons Newcomers → Homemade headers?
Anybody opposed?
KT
Mine would look much worse...
KT
What sized tubing into what sized collector?
KT
KT
http://www.autolounge.net/calculators/e … izing.html
My best guess of a 4,000 rpm torque peak on a 2.0L 4 cylinder is around 1.5"....
I'm all for homemade headers:
What's this collector thing you speak of?
Is for a mad rabbit turbo?
'Angry Bunny'
KT
Nah, that was from a previous project. Mizerable Mazda Miata. More fun was had in that one than should be had. In the end, when I went to sell it, the turbo scared the buyer so I've still got most of it.
Wait, don't many fords use the mazda block?
Somewhat...
You have some ideas?
KT
As long as you keep the receipts for the materials since headers aren't part of the free exhaust section of the rules, I can't see anything wrong with it.
Not sure if it'll fit, came off a 1.8 miata. It's yours for shipping. It's been sitting in my office making people ask strange questions on every video conference.
I want to make some wild 4-1 headers.
Thanks, though.
Will need to accommodate the O2 sensor, too.
KT
Anybody opposed?
KT
Yep, I am, no wait, headers usually screw up engine running, cause heat problems and take away torque, and sometimes HP, and best of all they break and cause lost time in the pits...
Go ahead and do it, I'm all for it!
They will be made of steel, BTW.
KT
Breakage is the biggest problem, from my perspective. Welding causes fragile spots that can only be corrected by normalizing the entire piece. Most of us don't have the facilities for that.
If you're gonna go with a home brew header, thermal wrap the hell out of it.
Details, details... 
KT
Alright fine here comes the details (don't hate me if this goes too long).
There's any number of header designs, that aside, you have to address the limits of materials.
The first problem is that steel expands. Worse, it expands at a rate different than the aluminum in your head. To complicate things, welding makes a mess of the malleability of steel, welds are fairly brittle (mig welds especially). If that wasn't enough, welds are generally thicker than the surrounding metal so it expands and contracts at a different rate.
Normalizing a piece will reduce some of these problems, especially when dealing with mig welds (tig welds don't cause the same problems to the same extent). Mig welding puts a lot of heat in a very small area, so the metal crystallizes in a manor that will tend to crack with headers. If the piece is welded, then put in a really friggin hot space (like 1000 degrees) for a bit and cooled extremely slowly, the crystallization will self correct and the welds will get much stronger.
Thermal wrap is also your friend. If the entire header is thermal wrapped, it won't heat/cool as fast. It'll come up to heat and stay there so expansion will happen slowly and not retract, adding stability.
After that, the best suggestion I've got is a decent flex coupling just after the header. The less stress you put on it, the better.
I'll take that manifold if you still have it rohar, I'd flip it upside down anyway to fit my B6t 323 GTX.
Sent you an email. Email me your info and I'll figure out shipping.
Fair warning people, looks like djcommie is gonna run at least 5 really fast laps 
My header lecture:
First, my business has a chassis dyno, and the dyno tells the truth.
In the past year I've learned that 95% of aftermarket headers on 95% of cars are worthless, even worse, most lose you torque and HP. Even high-dollar headers are suspect. I can't tell you how many customers have run their cars on our dyno, only to find that their GXBXZZ-JDM_22S/Greddy/spoon Mondo Header has actually lowered engine torque and hp. We put the stock manifold back on: magic, the power reappears! There are a few exceptions, mostly racecars with ported heads and very aggressive cams. On motors with stock cams and heads, just say no to headers, you'll end up saving time and money, and best of all you car will have way more torque and be more reliable.
I know, I know: your badass ride picked up umpteen-zillion hp when you put a header(s) on it. I say, let's run it on the dyno and see.
Oh, and We've never had a car catch fire on the dyno with stock exhaust manifolds, and have had many with headers catch fire...... You'd be be surprised how many times our fire extinguishers have been refilled....
I might just hog out the cat...
KT
The 24 Hours of Lemons Forums → Lemons Newcomers → Homemade headers?
