LightningTeg

Hey guys. I started tearing down my car this weekend and unwrapped my manifold to check for any cracks and low behold, its got one starting to form on the right side of the waste gate in the collector. Its not big but still a crack. This is a Go-autoworks ramhorn that is very nicely made.

The manifold has been wrapped since day one that I've had it on the car. I painted it with a couple coats of high temp paint then wrapped it with the DEI stuff and double layered it at the top part and spray painted it with the silicone spray stuff.

Now, I'm not whining or saying its Gregs fault or anything since I even bought it second hand. I just want to do everything possible next time around to keep it from happening and figure out exactly what causes it since the heat wrap helps tremendously with underhood temps. I think the weight of the turbo is a big factor but it seems all manifolds love to crack around the wastegate flange. I'm looking into making some braces to hold the manifold or downpipe from the block to take some of the weight off of the head since I also had issues breaking exhaust studs this summer.

The reason for the title is mainly because everyone says that heat wrap cracks manifolds but I'm not convinced.

kbouchard1092

The DEI titanium wrap? From my understanding you are not suppose to use the Spray with that wrap(something about it not bonding well to it) Not saying that would contribute to it cracking tho.

Do you monitor EGT's?

do you have any pics of the crack?

LightningTeg

Its not the titanium, its the conventional fiberglass.

No I dont, just AFR. Its just a small crack on the right side of the wastegate port weld on the collector

I dont have any pics.

4genaccordfreak

What kind of engine mounts are you running?
Most cracks are "usually" the result of lots of heat cycles which (can) make the steel brittle over time (but it's unlikely), combined with alot of vibration. If the weld didnt not have enough penetration it's even more likely to crack from vibration.

Companies like Full-race try to inhibit this by using pre-bevelled piping, an initial penetration weld then a finishing weld over top.

LightningTeg

I've got stock mounts with inserts all around. Its never "appeared' to move a lot but I've never seen it truly under load. Aftermarket mounts are my first order of business.

TheShodan

iTrader: (14)

Hmm. Interesting. I have both High heat ceramic coat AND Titanium wrap on my JDL Auto Design exhaust manifold with stock mounts. However, I am using an adjusted engine "stiffy" to prevent engine movement. Not one crack yet.

I'm thinking its the flex of the engine with the heat, and not from the wrap/spray combination.

wantboost

iTrader: (2)

Normally paint and wrap is a no no, the high heat paint will flake, especially on a manifold and could cause uneven wrap distribution or hot/cold spots

I know for a fact the DEI titanium/lava stuff needs to go on bare metal and it works wonders on our z06

And you can wrap a ceramic coated manifold... the ceramic is a tough and stable coating so it won't have issues with the extra heat from being wrapped as well


As far as the crack, heat cycling can cause cracks, wrapped/coated or not. That's why some companies slot the head flange to allow for thermal expansion. Most cracks always seem to form around the wastegate area.... the weight of the wastegate hanging off the manifold, combined with vibration and heat cycling will cause the metal to prematurely fail. You try hold 5-10lbs in one outstretched arm and tell me what it feels like and how long you last, eventually your arm will get tired, just like the joint at the manifold

And things other than that play in as well... weld quality, how much it penetrated, back purged or not, amperage used to weld the joint (while the weld can be strong, excess heat can cause the base metal around the weld to become brittle and weaken) I've seen it a lot

What wastegate are you running, the turbosmart 45? A wastegate that size I would strongly recommend bracing/supporting the wastegate runner.

GoAutoworks is a very reputable company, I'm sure Greg will be more than happy to resolve the issue.

kbouchard1092

Full-Race also Robotic Tig welds there Manifolds...ThIs will clearly be better then most hand welded manifolds(and clearly more expensive R&D resulting in higher costs)

It under warranty i would just send it back, They clearly provide good customer service.

I would just use the DEI Titanium wrap on bare metal. i know the regular wrap can hold onto water ( maybe excessive amounts with it being double wrapped). You do not soak the titanium wrap like you do with the convential DEI for install

LightningTeg

Its a standard 38mm.

Its not Gregs problem since I bought the manifold second hand so I'm not expecting any favors. I'll most likely have a local fabricator fix it up and make any changes I want. The thread is more to discuss the issue of cracking in general, but I'll almost always point to the unsupported weight causing the problem.

OneBadTurboCRV

Another factor that almost everyone overlooks is using the proper rod/filler. Elongation and yield are huge factors when dealing with heat cycles. Given they are not the only factor, but play a large part. Typically, with schedule 10 stainless (assuming 304) you want something with the characteristics of the 308H electrode. With these proper steps being used I have NEVER seen any welds crack as long as they are properly supported. This all comes back to the "enjunearing" stage, do it right or do it twice.

Things like penetration and amperage used to weld the product all come down to what is being welded, how its being welded, and to what skill the welder has. These factors have less than one would think to do with it. Back purging isn't everything either. That has more to do with end product and not the longevity of the weld.

Back to the wrap... it doesn't make a difference who what when why where it is coated or not under the wrap. The ideal setting would be to have it NOT coated in any circumstance. The wrap should NEVER be doubled up. That WILL cause hot spots. Using wrap actually gives stainless the best advantage it possibly needs - controled cooling. Anyone who fabs anthing can tell you a quick cool down with stainless will lead to cracks.

I have built turbo manifolds for rotary engines that last for years on end. For those that don't know, they see EGT's of 2,000*F on a regular basis. It's not so much the tools you use but rather the method to the madness.

LightningTeg

Word.

Here's the crack:

OneBadTurboCRV

Are you positive it wasn't there when you bought it? I am not aware of Greg's weld practices but I somewhat doubt preheating, postheating, and peening practices. It looks like heat cycling cracks caused from high stress on a weave weld. I am no "Professional Expert Engineer" welder though... I don't quote the book either, this may be best suited for the "Fab" section.

LightningTeg

Yeah I def would have seen it if It was there before

Turbo-GSR1287

iTrader: (1)

I had this samee thing happen on my old RCAutoworks ram horn in the same place. It's is most likely the heat cycle and weight of the wastegate. I ended up having it rewelded around and welded a brace from the manifold to the wastegate arm and never had an issue after that

Jimmynitro

Ive had a header crack on my Allmotor car which was header wrapped, I heard it like glazes the metal or Somethin n makes it brittle. It works but it will shorten the life of it, go with ceramic coating. That way the inside is coated. N the manifold won't get heat soaked. Also the vibration and weight of Wastegate will cause fatigue over time

justYncredible

iTrader: (1)

my thinking is it is the heat wrap. the heat wrap holds heat...doesnt it?

D-Rob

Wrapping any exhaust component will tax the material at a higher rate, since heat takes it's toll on pretty much everything.

Spawne32

iTrader: (3)

It does hold heat in, for a reason. You dont want the rapid cooling and expansion of metal at the joints of a weld. If you have ever done a long highway run on a cold day and you come home and get out of the car and you hear the sound of metal popping, thats the sound of your exhaust system contracting very quickly from the rapid loss of heat. While most of the time that will never cause an issue, when your dealing with the rapid rise up to 2000* and then back down again, problems can arise on welded manifolds. That crack looks like an issue associated with the weight of the wastegate. It's along the joint of where the weld meets the existing metal, and where the most expansion and contraction or "stretching" would have occurred during the welding process.

justYncredible

iTrader: (1)

I hear ya, but synapse turbo told me to not wrap there manifold because it can cause cracking of the manifold.

Spawne32

iTrader: (3)

Im not saying you have to, im just saying that it's unlikely that wrapping would induce cracking along welds. Most of the higher end manifold's are sufficiently thick enough and made out of a better grade of stainless that cracking shouldnt be an issue regardless.

TheShodan

iTrader: (14)

Then something is suspect with the filler they use in the welds?. I've NEVER heard of anything like from all the manifolds that I've used and have had made. Wrapped, coated, you name it.. knock on wood, I've never seen issues from that before unless it was a construction issue.

In Turbo LS's case, looks like the weld and wastegate location issue. Hope you get it taken care of

OneBadTurboCRV

If you guys are worried about what your CHEAP manifolds are doing, try building one out of 330 stainless... That WILL leave a hurting on your tiny wallet.

I think everyone is missing the point... you wrap the metal to keep a more consistent temperature and for a more linear cool down phase. The metal is going to be "taxed" no matter which way you look at it - it has EXHAUST gas flowing through it... and to top it off flames licking the walls. The cycling is the problem or the "roller coaster effect"...

If you still don't get it, weld a few stringers on a plate and let it air cool. Do the same thing with another plate and dunk it in water. For a third plate preheat the steel, weld the stringers, post heat the plate and wrap for cooling. Tell me which one is warped the least amount.

Another factor people don't consider is rain... you are driving a setup that never was intended for moisture to hit it while it was at operating temperature. Why do you think cars come with cast manifolds (aside from cost and production)? They are much more durable than something that has a "built in" life cycle.

SovXietday

308L filler is the general "industry" standard, I don't think I've ever seen 308H? Will have to do some research to see what the difference is there.

Pretty much no matter what these manifolds are going to give up at some point. It could be 20 years down the road (preferably) but eventually they're going to have issues. Unfortunately the rapid heat cycles that most of these things go through cause massive stretching and shrinking, which over time is going to deteriorate into a failure.

Just remember, not only does your manifold get slightly longer when it heats up, but it also get slightly wider. I think that's a lot of what contributes to the cracks around the wastegates. They are welded in such a fashion that there is stretching in all directions perpendicular to their base weld, add that with the heavy weight of the dumptube + wastegate + vibration and it'll eventually just pulls apart the base of the weld.

OneBadTurboCRV

I am sure there is more out there as I have only been welding for 40+ years... this link should give you everything you need to know:

http://www.aircraftmaterialsuk.com/d...ld/ER308H.html

If that confuses you or doesn't mean much, then this should break it down enough for layman's terms:

http://www.lincolnelectric.com/en-us...lectrodes.aspx

Want to buy some?

http://www.airgas.com/browse/product...oduct=AVE59427

It says 600* C but that is for optimum holding power for 308H. You can use it to temperatures of 800* C and still be at 20,000 psi...

(Just in case you didn't know, 308L has a service temperature rating of 315* C... )

wantboost

iTrader: (2)

330 would cost as much if not more than the car lol
But it deifintely would be the choice for a manifold, next to inconel