Had a local fabricator make a new sidewinder manifold, dp and 44mm vband wg (open) setup for me on my S2k. Everything fit great and the car was running awesome with the exception of the dump tube. It was vibrating against the subframe when the engine tq'd forward. I got the car back with everything put together on Fri night and drove it Sat & Sun until I could get it back to him on Mon to fix the clearance issue. Yesterday he loosened the vband and rotated the dump to get it away from the subframe and all was well until about 20 miles later down the street from my house. The car makes no boost and sounds like a diesel. Pop the hood and find:



Now - few caveats. I'm posting this not to bash the fabricator and place blame. I realize these things happen and its the nature of the beast. I'm posting this to try to get a sense of why it happened so it doesn't happen again when he fixes it. I've narrowed it down to three possibilities:

1. Vibration from contact between the dumptube and subframe was absorbed at this weld and eventually it let go (most likely)

2. When the dump was rotated yesterday, it put some kind of undue stress on that weld and caused it to let go

3. Poor weld

I know #3 is pretty impossible to determine without a closeup but I can't leave it out of the realm of possibility. The manifold itself its braced against the motor mount so I'm pretty sure thats got nothing to do with it.

Ideas and opinions are greatly appreciated.

- D

 

From what I can tell it looks like a poor weld and everything else just made it worse. The weld looks too cold with no penetration and so does the weld on the collector. Pull it off and take some better pics of it.

 

Well, obviously the wastegate should not be whacking against the frame rail... soo...

As far as the welds go I've seen nicer welds fail and uglier ones hold up. So who knows. It's rare to get a pic that REALLY shows what' happening IMO.

IMO there isn't THAT much mechanical stress going on (well, there was in your case, but normally there shouldn't be) so I would not be that worried about the weld.

Fix whatever the packaging issue is and see how it goes.

Even if we tell you - yeah it's the weld - what are you gonna do? Have the whole thing re-done?

Fix it, make it not hit the damned frame rail, and see how it goes.

 

#3 is your problem. i'm going to guess it wasn't welded on the inside either. a more common failure would be where the branch joins the collector, not the wg flange to branch.

it looks like it is coated too, that will have to come off, everything should be ground clean with a carbide burr or something before the repair, so not to contaminate the new weld.

 

If I get enough opinions that its the weld, I'll let my fabricator know to take more time on it when he redoes it.

weirtech - yes it is cermaic coated. Sucks because I waited 3 weeks for it to be done and now it has to be washed away for this repair.

 

yeah that sucks. i tell all my customers to run the manifold for a year, then get it coated. that way, if there are any issues, i can look after it right away and they aren't out any $ for coating. usually if something is going to fail, it will be in the first 10k miles or so.

 

S2000s also have very bad harmonics around cruising rpm 3-4k. You can literally hold the engine at that rpm and watch the whole turbo setup shake itself apart. Not gonna lie, the only two manifold failures I've had were on s2000s...Both were at the wastegate port where it attaches to the collector. Tell him to brace the wastegate to the manifold, it should help.

 

^^^ good to know!

 

thats kinda ironic i just had my first failure of a manifold on a s2k.... weld cracked at the wastegate flange like op, but i saw my problem was from a cold weld. fixed it welded inside and out and braced it.

 

the dump tube and DP needs to be braced or there will be alot of leverage from the end of the dump tube to the WG.

 

UPDATE



After the first crack was repaired, look what happened two days later:



My dumb luck.

My fabricator said the exact same thing...only failure he's had has been on my car. So he took the manifold and repaired it again. Here's what I'm running now:



Hopefully it will hold together this time.

 

Those welds are no bueno

I wouldn't be surprised if you had cracking issues else where later down the road.

 

Whats wrong with them?

 

I'm not trying to say the welds are the best but other things can play a factor into the crack, I'd like to see the dumptube and how that is setup. The vibration from the dumptube and the frame rail is defiantly not helping anything.

 

The issue with the vibration is fixed. Dumptube touches nothing now, exits next to the oil pan

 

if you want to help brace the end of the dumptube it is moving a lot around 4k

you can put your finger 1 inch distance from the tube and felle it touching it when you rev your engine to that speed

 

What material is being used for it ? I'd brace the end of it

 

Did roque ever fix this? not knocking the guys but i have heard of his intercooler piping blowing apart.

 

Those welds are cold. Not to mention, not enough filler and spacing is all over the place. The bracing may not have been necessary if the welding was done correctly, but it's good that they are now in place!

 

Umm yea did you see the last picture I posted?? Its fixed. Made 454whp last night @ S&R.

Who are you and how did you know it was Roque lol?

 

depends on the type of metal too or maybe the motor torque back n hit against something.

 

My guess is that the welds were your original issue. I may be wrong but stronger welds that break, fail in the HAZ and not down the middle of a weld. I agree, the welds look cold and dip spacing is too far apart. If the same weld techniques are still used to repair this mani, you may not be in the clear just yet, so keep us posted.