tubular headers/manifolds

[mitsuturbo]

Which tubular exhaust manifolds out there are worth buying and which are not?

Who's had/seen examples of manifolds that crack? Who's been running tubular ones that have held up for a good long while? I've been thinking of going with a tubular manifold, but i've heard nothing but bad things about them cracking and breaking. I remember hearing at one time how great the SFP manifolds were, now i am hearing they're colossal pieces of garbage.

 

[rgeier11]

I've had an SFP manifold for over 3 years and I haven't had any problems. Then again, I only drive my car in the summer and I had it jet hot coated.

 

I really dont think there any perfect manifolds out there. I've seen a cast aftermarket one crack all the way around. Tubular manifolds cracking at welds. Some people dont have problems, some do. I personally would go with a tubular because you can always have it re-welded.

 

[atc250r]

I believe it was an SFP that Underground had on his car. It cracked a couple of times but the final straw was when the WG tube cracked off completely and the WG was hanging by the hose, banging off the pavement at 60mph on the highway. I think at that point he gave up on playing with that thing, even though it was covered by a lifetime warranty what good is it if you're constantly sending it back. That was a pretty old manifold so they may have gotten better by now. IMHO, cast and tubular both have their flaws. Personally, I'd go with the cast one.

John

 

[VR4coop]

I had a DNP that cracked at the flange. Re welded it, sold it and bought a FP cast. Easier to work on and half the money.

Thanks
Clint

 

[iLLeffeKt vr-4]

Full Race makes some nice manifolds. I have two friends that have them on their cars and so far no issues once so ever. Their prices are steep ($1300+) but they look very well built.

 

[Brianawd]

I have a dnp on my car. I got it used. Granted I don't drive my car all the time but when I do I get the manifold hot as hell. Still no cracks.

 

JMF makes a really nice manifold /ubbthreads/images/graemlins/smile.gif

 

[iLLeffeKt vr-4]

I thought they only make it for EVOs

 

[onesickcrx]

Nope they make it for dsm's and even vr4's

 

[dsmless]

I use a slowboy racing cast mani, looks good and flows great you can have them cast for a t3 t4 or mitsu flange, very beefy and can have the #1 runner set for 38 mm wastegate mount, price is at 375 to your door, very happy with the results

 

[curtis]

I've re-welded a bunch since my buddy owns a import shop. Even welded the sch 10 on his evo last week that was only 3 months old It had cracked 360 on the first elbow joint on #2 and 270 on #3 as well as the wastegate tube was cracking length wise. /ubbthreads/images/graemlins/dunno.gif

Now what causes cracks and how to prevent them from cracking.
Heat, vibration, mass and carbon loss.
Heat makes the bonds in the grain structure go active this makes the tubes move from cold to heated state over and over. Some people weld in between runners but that can make things worse and is a band aid fix.
Other cut slits in the mounting flange on the head because the coeff of thermal expansion is different between the two materials. This does help but the best two things to do is brace the header and and have it coated inside and out. There's plenty of unused bolt holes of the front of the block. Try using more than one and also brace the downpipe up. Turbos hanging from headers can be 10 to 100 lbs and just the harmonics from the wheels and shaft spinning upwards of 150k can break down a weld or the material next to a weld. But the biggest killer is heat, this is why stainless is used and coatings are so important. Exhaust gases are +1000 degrees most of the time the metal gives up carbon atoms as it cycles after the carbon releases enough bad things happen, mild steell gives up carbon faster. Another good reason for coatings is the heat the more heat put to the blade the faster it spools and works.

 

[Barnes]

Mayhaps someone should make an Inconel tubular header. /ubbthreads/images/graemlins/cool.gif

 

[3rdstrikedsm]

shearer makes about the best ones.

 

-Sch 10 1.5" 304 stainless pipe.

-TIG welder set to D/C at about 100 amps, 3/32" Tungsten, 3/32" 304l Filler rod.

-*Completely* Back purged with argon. (Inside of the pipe to be welded)

-Never re-weld again.

This is what Shearer does, and what every good fabricator does.

If your manifold has all these things considered into it, it will last forever. No coatings, brackets or other band-aids needed.

You guys are making serious horsepower now-a-days, welding skill should be a given.

Shearer is nice, but, backyard Honda guys have been making manifolds like this for YEARS.

 

[Andy_S]

Quote:

You guys are making serious horsepower now-a-days, welding skill should be a given.




Thats why I have friends that weld. I don't know how to weld, have never welded before, and probably won't learn anytime soon. I would, but I don't have the time or equipment. Sometimes things are best left to specialists. Just because I can't weld doesn't mean I can't build a fast car.

 

[Barnes]

Quoting number638:
You guys are making serious horsepower now-a-days, welding skill should be a given.



LOL! That's rich. Even if I was a good welder, which I'm not, I'd rather have a weld shop put things together for me rather than spend the $2000+ for a good TIG setup.

 

Quoting Aspod:
Just because I can't weld doesn't mean I can't build a fast car.



I never said you couldn't. In fact, I said you Do.

$2000+ is "rich".

Here try this:

Miller Diversion AC/DC TIG is $1275

 

That looks like a great alternative to super pricey welders! I don't think I would trust it to make a manifold though. It has a pretty limited max thickness of materials it could weld though. I think it's probably perfect for what I do though, aside from building thicker material items, but I could just use my friends set up.

 

[onesickcrx]

A picture of JMF's work