The manifild I posted on the first from FULL-RACE.com comes with a lifetime warrany against cracking. Then again it's $1000+ and they dont make one for a Miata.

 

I bet it's made of better than 16 gauge thick material too. Exhaust gas and heat do their work more efficiently when they stay in the manifold.

 

Actually they did make one for a Miata as a custom job... It is in their gallery.

 

Link?

 

http://www.full-race.com/Miata.html

It's not on their site anymore that I see... That link was pulled from a Google search. So the thumbnails might not enlarge. At least I can't get them to...

 

it probably broke

Nobody told them, that they cant build a miata manifold like a honda manifold

 

Haha! Very possible... Good thing it had a lifetime warranty against it for the buyer. Maybe that's why the only made one and won't make another... I tried in the past.

 

Why not?

 

honda engines are hella smooth, you can make a big lanky manifold out of thin steel and the thing will be fine. The BP has some serious vibrational issues, thats why you gotta use sch 40 pipe, that kind of stuff is beyond unheard of in the honda world. Most ppl would say sch 10 is overkill

 

Or they found out that we are all a bunch of cheap ************* who are unwilling to pay $1500-2000 for a robotically TiG-welded manifold. I've held a T4 twin-scroll Full-Race manifold with twin EWGs in my hand, it made me a little hard, and then the $3400 price tag immediately made me soft again.

 

3400 bucks!

who needs robotic precision when we got turbotim an artech.

 

Story of my life.

 

ahhh...gotcha. I thought all 4cyls were inherently out of balance relatively equally (hence balance shafts on some larger displacement 4bangers and high revvers like the hayabusa). I would think a 1.8 honda would have the same vibrations as a 1.8 mazda.

 

Gawd damn...

 

Then why are there so many posts in Honda forums on cracked turbo manifolds and so many manufacturers offering Honda manifolds guaranteed not to crack?
Just asking.

Is there a reason the honda engines are balanced better? I figured one production inline 4 cylinder would be relatively similar to another.

I would think a thin wall tube manifold would heat soak the same on either. If you get the material into a heat range where it can soften, it will fatigue because of the load it's trying to support anyway. Thin wall tube is real easy to heat up. I cracked my thin wall manifold 5 times before I finally wised up and made it with .187 wall tube. Now no problems whatsoever. It holds the heat in so well, the VHT paint I used isn't even flaking and it spools better.


Just saying. It seems like most of the premium manifolds are made of thicker material also.

 

Idk, I really dont think the BP is as smooth. Think about all these weird failures we have at high RPM, breaking throttle shafts and oil pumps and whatnot.

People apply a lot on generalization to honda engines, like assuming they all have good rod ratios which is why they rev safely. But in reality many engines have rod ratios that are extremely similar to ours sometimes even worse. Yet they have no issues reving to 8k+ rpm.

No doubt there are manifold failures on hondas, but from what I gather its because of very light materials, much lighter than any of us would even consider a possibility. Like those "SS autochrome" ebay manifolds. A miata couldnt get out of the driveway without cracking one, while honda guys will ge away with running one for hundreds, even thousands of miles before it cracks (but they still always crack)

Ive always assumes that it has to be vibrational. The only other thing I could think would be that maybe since we tend to run undersized turbos and they tend to run oversized turbos that maybe the smaller turbos are creating a lot more heat in the manifold that is fatiguing them faster.

All I do know is that many members of this forum will say "sch 40 is a minimum", and if you say that youre building a manifold out of sch 40 on a honda people will think that your cheese done slid off your cracker.

 

They're balanced more accurately to stop them breaking as they're quite revvy motors, if they weren't so well balanced then Honda would have been inundated with broken ones under warranty!!!

The manifolds crack most of the time because they're not back purged when they're tig'd. Good luck to the guy that has to tig a manifold back together once its been used.

M.

 

Or they are a thin wall tube that gets heated up to the point where ductility is reduced resulting in an inability to structurally support anything. How many manufacturers really do more than weld it and send it out the door? I bet not too many, it's not cost effective.

I haven't heard of too many thick wall manifolds cracking though. Just my 2 pennies.

 

I could see that then. Bigger turbo=more hot side flow=less restriction resulting in inherently lower EGTs. This coupled with a slightly smoother motor may just make a difference.

Dem Honda bois do luv dem huger turboz.

And I hate when the cheese slides off my cracker, someone needs to address this issue! Some cheesy weld or something.

 

our oil pump problemb is just a design flaw, ford mod motors use the same pump design and they fail at high rpms as well. iv even seen mustangs break billet gears : O. Wonder who will be the first to break a set of boundry gears in a miata.