D.O.C Race manifold/collector. First Post!

[sarg]

Especially if slapping a $1000+ plus turbo on it, haha. Money is too hard to come by to waste for me. The extra $5 it costs to backpurge is worth it to save my $1400 turbo.

[turbosnail]

Thank you for all the informed opinions.

The item I received is most definitely not what I expected to receive. Coming from a family in the NDT business, I almost wanted to cry when I first saw it. The company offered to "clean up the welds", if I ship it to them at my cost. I live half way around the world from them. I have asked to return it for a full refund, with no response. But that is beside the point.

I can't really afford to replace it (it already cost me over $2000 landed at my doorstep).

What are my options here? Can it be saved at all? Or can I do something to prolong it's life? I have a very expensive turbo to go on it alongside my very expensive engine. 30+psi, 600hp. Doesn't sound like it will last...

[MikeGyver]

hmmm. from a consumer standpoint, I'll take the manifold that's backpurged and welded with full penetration thank you.

Ok it costs $300 more to cover the extra time involved, and carries the same warranty. Believe it or not there's more to purging that taping the ends off and turning on the argon, it doesn't just add 2 minutes to the job.

Especially if slapping a $1000+ plus turbo on it, haha. Money is too hard to come by to waste for me. The extra $5 it costs to backpurge is worth it to save my $1400 turbo.

Yeah go find a shop that works for free labor. And its more like $20 in argon. If it's something you're building yourself then yeah backpurge it, labor is free and it's not something you'll have much experience doing so you'll want that safety margin.

It irks me when people bring me a dirty stainless turbo pipe or something and need one weld, and they don't understand why it took me 45 minutes to weld it. How bout this, I'll hold the mig gun and you rotate the pipe in front of it and tell me when to pull the trigger, then we can make it a "5 minute job".

[sarg]

Ok, so $20 in argon and $2 in foil. I am not talking out of my *** here, I have done this on manifolds as well as turbo pipes. It really is not that big of a deal. Least it was not for me. My junk is not perfect, but at least I know the whole thing was backpurged. If it cost me an extra $20 or even $50 at least I know it will save my $1200 turbo. IF you are going to all the trouble to weld up a nice manifold like that, the extra $20 in argon is probably worth it. It honestly is not that much more time in my experience. Maybe I am doing something wrong, but all my welds looked nice on the inside.

[Jwdiho]

Ok it costs $300 more to cover the extra time involved, and carries the same warranty. Believe it or not there's more to purging that taping the ends off and turning on the argon, it doesn't just add 2 minutes to the job.

No one said they thought it was taping off the ends and another 2 minutes. I assume most of us are on this site because we share some interest in welding and appreciate a job done properly.
But like I said, if it were my money, I would prefer a manifold welded that did NOT look like the pictures posted above.

The price will be what the market dictates. It may or may not be another $300. And warranties mean nothing if the company goes out of business cause their manifolds all failed.

I understand where you are coming from. I just would prefer not to shop where you are coming from. Just my 0.02.

[sqznby]

turbosnail,
It is very unfortunate to have to deal with that. It's going to need a bit more than just a better die grinding job.
Where are you located?


Isn't the cost of argon factored into the price anyway?

[MikeGyver]

I understand where you are coming from. I just would prefer not to shop where you are coming from. Just my 0.02.

Well that's your loss because I purge everything I do. Try reading more than half of each of my posts if you can manage...

I'm just playing devil's advocate to thwart some of the dumber comments and mentalities spewed forth in this thread.

[76GMC1500]

Well that's your loss because I purge everything I do. Try reading more than half of each of my posts if you can manage...

I'm just playing devil's advocate to thwart some of the dumber comments and mentalities spewed forth in this thread.

Mike you did good defending some well intentioned entrepreneurs but they ****ed it up for you. You are right, not everything needs to be purged and they could have done what they were doing without it. But they lacked the skill to make what they were doing without purging. Though Solar B flux would have done them very well. But yeah, everybody else was more right for the time being that DOC should have purged, but they did not. But who cares? Is DOC even in business anymore?

[turbosnail]

turbosnail,
It is very unfortunate to have to deal with that. It's going to need a bit more than just a better die grinding job.
Where are you located?


Isn't the cost of argon factored into the price anyway?

I am in South Africa. Online research led me to believe that these manifolds were produced to the same quality as Full Race - back purged, etc. They are almost identical in price! Of course, now that I show people pics at the same forums I did research, they all say "oh yes, they don't back purge anything". Wish they told me that earlier...

I have a local welding company who is very skilled, but don't want to have them cut the manifold apart and weld it together again. It would be too much to expect them to make it fit the car again as well.

Mike you did good defending some well intentioned entrepreneurs but they ****ed it up for you. You are right, not everything needs to be purged and they could have done what they were doing without it. But they lacked the skill to make what they were doing without purging. Though Solar B flux would have done them very well. But yeah, everybody else was more right for the time being that DOC should have purged, but they did not. But who cares? Is DOC even in business anymore?

Yes, they are very much in business. I just bought this manifold a couple of weeks ago! They have parts running on some high profile professional drift cars. I wonder if they are the same quality as this?

[fordman]

It appears to have a pedestal for a turbo on it. So yes it will be under pressure. Not much, but between that and the heat cycles, it will crack eventually.

The pressure is coming out the other side of the turbo, the exhaust just drives it.. Just sayin,

[VPT]

The pressure is coming out the other side of the turbo, the exhaust just drives it.. Just sayin,

There is more pressure on the exhaust side than the cold side of a turbo.

[76GMC1500]

There is more pressure on the exhaust side than the cold side of a turbo.

I would say no. The engines I run see about 15-20 psi on the hot side and 50 on the cold side. Caterpiller 3512. It's not the pressure that drives the turbo its the mass flow and heat that does. You only need the pressure to get it to the wheel.

[MikeGyver]

I would say no. The engines I run see about 15-20 psi on the hot side and 50 on the cold side. Caterpiller 3512. It's not the pressure that drives the turbo its the mass flow and heat that does. You only need the pressure to get it to the wheel.

Sounds to me like the compressor would just surge and want to run backwards if you have 3x the pressure on the cold side...
Is that a diesel motor? that might be different but for gas it's true there is. It's pretty commonly accepted knowledge that it's around double or so. The turbine housing is by far the biggest restriction in the flow path of the engine, and the air is super heated right before it gets there.

[sqznby]

I am in South Africa. Online research led me to believe that these manifolds were produced to the same quality as Full Race - back purged, etc. They are almost identical in price! Of course, now that I show people pics at the same forums I did research, they all say "oh yes, they don't back purge anything". Wish they told me that earlier...

I have a local welding company who is very skilled, but don't want to have them cut the manifold apart and weld it together again. It would be too much to expect them to make it fit the car again as well.

You certainly aren't right around the corner. I am sorry you have had to deal with such services, especially being so far away.
I am shocked to see that they are pricing them as close to the competitors as they do. Cut corners and charge full price, that's just wrong.
Good luck with the local shop. I wouldn't recommend cutting it up, like you said the chances of it fitting correctly will be slim and even more money down the toilet.

Are the pro drifters local to you?

[turismolover22]

The hot side of a turbo will always have higher pressure in it than the cold side. This isnt theory, its fact.

[Meborder]

throughout the majority of an engine's powerband, this is correct. however,at the engine's peak VE, the pressure ratio can be less than one


pause the video at 0:09 and you will clearly see the exhaust back pressure less than the intake manifold boost.

the operating speeds at which this can be achieved is decidedly narrow, though.

[turbosnail]

You certainly aren't right around the corner. I am sorry you have had to deal with such services, especially being so far away.
I am shocked to see that they are pricing them as close to the competitors as they do. Cut corners and charge full price, that's just wrong.
Good luck with the local shop. I wouldn't recommend cutting it up, like you said the chances of it fitting correctly will be slim and even more money down the toilet.

Are the pro drifters local to you?

The pro drifters are all in the US. Impossible of course to tell if they received their manifold in a similar state originally.

So much for research and opinions on the internet.

Thanks for the help, I hope it doesn't crack apart anytime soon...

[fordman]

There is more pressure on the exhaust side than the cold side of a turbo.

I guess with heat and the energy it takes to spin the turbo it creates a bit of pressure. I didnt know that

[VPT]

throughout the majority of an engine's powerband, this is correct. however,at the engine's peak VE, the pressure ratio can be less than one


pause the video at 0:09 and you will clearly see the exhaust back pressure less than the intake manifold boost.

the operating speeds at which this can be achieved is decidedly narrow, though.

That is interesting. I haven't seen this on either my 7.3 or 6.0 using AE datalogging. But one thing about your video that I am curious about, are you running a compound turbo setup?

[turismolover22]

You also have to remember that on any vehicle, the exhaust should technically have a higher pressure than the intake. Using our heads and science, we know from using air compressors that anything at a higher pressure than atmospheric wants to move from a higher pressure, to a lower pressure. The gas inside an engine, once "burned" does not complelty burn until it begins to exit the combustion chamber. This gas also increases temperature as it exits (as we all know).

Now, we can safely assume that no one here believes the piston "pushes" the gas out of an engine. This is why headers are an "upgrade" as they increase flow, which, in turn, increases the amount of exhaust that exits the engine, through both flow, and scavenging.

The same applies for the intake side. The engine more or less creates a vacuum, which draws the air in. On a turbo setup, this is where we see our boost (under load). The only tim I would think that the exhaust pressures could be lower than intake would be on a well build supercharger setup.

And not to knoch anyone's testing, but the only way to truly compare exhaust/intake pressures is to tap directly on the manifold, and right after the turbo. Doing it off the downpipe or a compound setup is inconclusive data. After the turbo most exhaust gasses are 3-500 degrees at best, I've seen turbos glow red, but after about a foot the downpipe looks like cool steel.

[Meborder]

That is interesting. I haven't seen this on either my 7.3 or 6.0 using AE datalogging. But one thing about your video that I am curious about, are you running a compound turbo setup?

just a random youtube video, sorry, not my truck.

there is also no way to know if his exhaust pressure sensor is before or after the turbine.

however, it is a fact that the intake manifold pressure can exceed the exhaust manifold pressure on a turbocharged engine. Most times it will not, but if built correctly, when the engine is running at its peak efficiency, it is possible to create more boost than backpressure and achieve a boost ratio lower than 1:1. This phenomena is made possible by the velocity which the exhaust gases exit the engine and the temperature gradient across the turbine. The combination of these two energies exceeds the energy required to make the same amount of pressure on the intake side. In order to achieve this, though, everything has to be sized right, as well as a extreemely efficient exhaust down stream of the turbine.

the same way, while it is rare for a naturally aspirated engine to exceed 100% VE, with proper tuning in a narrow power band, it can be done.