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3 restos WIP = psycho
 
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Supercharging would make this conversation moot. LOL.
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Old 01-14-2010, 08:18 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #101 (permalink)
3 restos WIP = psycho
 
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Quote:
Originally Posted by WERK-I View Post
He was talking about the turbocharged Cosworth Indy Engine. High overlap cams are not a good solution for any turbocharged engine.
Never speak in absolutes. Have you seen the overlap numbers on the 2.1 RSR Turbo??? Big, like 'S' cam big. Definitley not good for a street engine, but any engine?

If interested in seeing them, I can dig them up, but not handy now.
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Old 01-14-2010, 08:21 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #102 (permalink)
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Quote:
Originally Posted by WERK-I View Post
1.) An ideal header for a turbocharger will have the shortest primaries possible.
A turbocharger is driven by the velocity and energy of the exhaust gas.
2.) It will incorporate equal length primaries to aid scavenging (correct spelling) and insure exhaust pressure pulses do not overlap, which build up back pressure on overlapped cylinders and create uneven exhaust pulses fed to the turbine.
The length of the primaries before the joint is determined by calculating the desired rpm operating range and pipe diameter. The traveling pressure wave out one primary pipe will create negative pressure in the adjacent cylinder which will aid the scavenging of exhaust when that cylinder's exhaust port opens.
3.) And there's the quandary; Doing both without compromise, is impossible.
Cheers, guys. Interesting thread, this.

I suppose, thinking about this logically, aside from all the other benefits of twin turbochargers (quicker spool), with fewer exhaust pulses (3 in our 6-cylinder case) per turn of the crank, I suppose this allows for shorter-length primaries?

Taking this line of thinking to its ultimate conclusion, then, we could have a tiny turbo for each cylinder?
Old 01-15-2010, 12:52 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #103 (permalink)
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I agree with Werk1 on Brian's system - its the best for the street & for built motors that will be used on varying tracks and situations. Like I said on my tt motor, its equal length for many reasons - and it works incredibly well.

Brians equal system with a zork is the ticket - i'm only doing the 935 headers as I have to fill the spot where there is no bumper on my K3. Otherwise i'd be in brian's system in inconel without a doubt.
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Old 01-15-2010, 01:08 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #104 (permalink)
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Brian, are you thinking about doing anything for the 993 turbo? I'd be interested in a nice set with heat if they'd offer a benifit over stock
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Old 01-15-2010, 02:22 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #105 (permalink)
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Eventually. My focus is of course the 930 and 965. I've been working on a 965 system for some time and will finish it after the 930 heat exchangers are done.
The 993tt system could easily be adapted for tt 930/965 by just flipping the flanges which makes that project more viable than just as a replacement for the stock exchangers.
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Old 01-15-2010, 05:33 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #106 (permalink)
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Quote:
Originally Posted by WERK-I View Post
I have complete faith in Brian's new product. I believe it would be d@mn near perfect if it had a centrally located turbo flange, but our crammed 930 rear-ends make it difficult and costly (cosmetically and financially) to do otherwise. I can't wait to see Brian's dyno results so we can put this trampled debate to rest.
If you look close at Brian's design, the turbo flange is centered between the collectors, since both sets of equal length primaries are offset to the drivers (US driver )side.

True equal length primaries and secondaries, packaged for a 930.
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Old 01-15-2010, 05:36 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #107 (permalink)
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Here is some interesting exhaust theory points of interest I came across elsewhere:

"...
Boundary Layer

The thin layer of air against the walls of an exhaust pipe. This layer buffers the effect of both the temperature and speed difference between the gasses inside the pipe, and the walls of the pipe itself.

Turbulence, your number 1 flow restriction

Turbulence is any gas not moving in a uniform direction (normal to the flow field), or against the overall flow of the other gasses in the pipe. It is by far the number one restriction in most pipes. It is also more common than you probably think. Almost any bend in pipe causes significant turbulence. (The turbulence comes in the form of vorticity when the pressure and density gradients are not alligned. The greater the mis-allignment, the greater the vorticity.)

Reduced turbulence = increased flow.

The only other real restrictions are changes in velocity. If the gas must speed up quickly it will require energy to do so. That energy usually comes in the form of pressure; backpressure in the case of an exhaust system. This pales in comparison to bad turbulence, but it's still worth noting.

Believe it or not, it really isn't the size that counts.

Size is only a factor in a very complex equation when it comes to gas flow. ... A larger pipe tends to have a more stable boundary layer because the gasses inside it are flowing more slowly. If the gasses are moving too quickly it rips off the boundary layer constantly, causing turbulence. The more stable the boundary layer, the less the turbulence, the better the flow. Corky Bell was probably referring to the boundary layer when he stated that there was a specific exhaust (and intake) gas velocity that ought not be exceeded.

Thermal coatings help stabilize the boundary layer by decreasing the difference in temperature between the boundary layer (which is about the same as the pipe) and the inner gasses (which are much hotter). Having a more even temperature reduces the effects of convection between the hot and cool gasses, which reduces turbulence, which reduces backpressure. Neato

Now to the last problem ... bends!

Whenever the gasses move through a pipe at an angle there is turbulence. This is because the diameter of the outer edge is much larger than the inner edge.

That difference in diameter means that in order to go through the bend at the same angular rate the outer gasses must move at a higher linear rate. This either causes backpressure because the outer gasses have to be accellerated, or it causes turbulence from shear forces because they don't speed up. Either way it's not ideal. ...


...because of the swirling pattern of the gasses exiting the turbine, the first 18-24" of exhaust pipe does not follow the rules in the same way that the rest of the pipe does. It does still follow the rules however, just the swirling that increases the local exhaust gas velocity considerably. ..."
Old 01-15-2010, 06:57 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #108 (permalink)
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Quote:
Originally Posted by RarlyL8 View Post
Eventually. My focus is of course the 930 and 965. I've been working on a 965 system for some time and will finish it after the 930 heat exchangers are done.
The 993tt system could easily be adapted for tt 930/965 by just flipping the flanges which makes that project more viable than just as a replacement for the stock exchangers.
The most relevant thing I have gotten out of this thread is that Brian's set-up creates a lean condition, suggesting that it works really F#cking good at flowing exhaust.

That to me is more important than academic would-have could-have.

Brian built a header system which looks like it really works. A equal length, and pretty freaking short system as well.

If we really wanted to answer all these questions we would be taking donations from all the people at this board to pay for Brian to test his system versus a B+B versus a Euro and also American stock set up. The rest is just making academic assumptions.

That is my two cents worth.
Old 01-15-2010, 07:34 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #109 (permalink)
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Quote:
Originally Posted by DDDD View Post
The most relevant thing I have gotten out of this thread is that Brian's set-up creates a lean condition, suggesting that it works really F#cking good at flowing exhaust.

That to me is more important than academic would-have could-have.

Brian built a header system which looks like it really works. A equal length, and pretty freaking short system as well.

If we really wanted to answer all these questions we would be taking donations from all the people at this board to pay for Brian to test his system versus a B+B versus a Euro and also American stock set up. The rest is just making academic assumptions.

That is my two cents worth.

That would be great, if he had the dyno for a day, and had all the headers there, and simply swapped them and run each of them on the car, all on the same day, that would be invaluable information! I don't even have a single turbo motor now, but i'd be up for chipping in something to cover the costs.... What are we looking at Brian for a day renting the dyno and a day of your time? Do you have access to all of the different headers to test? Stock US, Stock Euro, B&B, GHL etc
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Old 01-15-2010, 08:10 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #110 (permalink)
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I think the verdict is clear for those who don't have a vested interest in something they want to sell to others:

1. scavenging is not as important as reduced volume for a sports car.

2. Equal length is not as important when you are not using a divided turbine housing. If equal length
can be achieved without excessive flow losses and volume increases, it is overall beneficial.

3. Pulse conversion is the best way to improve response. This requires a completely divided system wth both sides isolated from each other. In this case equal length is required, along with a divided turbine housing. The collector volume on each side should be minimized as much as good fabrication practice will allow.
Old 01-15-2010, 08:23 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #111 (permalink)
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Yes, yes-- the lean AFR at idle could be an indication of a nice potential improvement!
Old 01-15-2010, 08:40 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #112 (permalink)
 
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Quote:
Originally Posted by 911st View Post
Yes, yes-- the lean AFR at idle could be an indication of a nice potential improvement!
Or an exhaust leak, or an air leak after the metering plate, or an offset to the O2 sensor due to contamination.
Old 01-15-2010, 08:49 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #113 (permalink)
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I apologize but this thread was not intended to be a Brian v B&B vote!

Nor a mine or my friend's is best and yours suck, thread!

It was intended to help me and hopefully others explore the theory(s) that differentiate a good equal length from a good low volume design.

Brian's is not the only equal length 930 header builder and there are actually quite a few. However, until now most have been to expensive for most and or to make them a popular choice.

We are lucky to have Brian's new system coming on line.

However, theories are just that.

I would truly expect Brian's new true-equal lengths to blow away the stock late/euro 930headers!

I also truly hope they blow away B&B style units on lag and VE. I suspect this is a strong probability.

A better comparison of a low volume system to and equal length might be Brian's new 'truly equal length' system to his/M&K's 993 / 930 system.

I to am looking forward to any dyno tests.

Especially if back to back.

I would just hope any such tests would be controlled for AFR and boost as these are significant variables on a turbocharged car.

It would also be interesting to fill up the different headers (stock, B&B. Brian's) with water and measure the result to see how much the internal volume actually varies between units, including WG tube. They may not be as much different volume as we think.

Again, I did not intend this to be a slam Brian's headers thread in any way. Only an educational experience for some of us that are interested and those that might follow.

The best to all.
Old 01-15-2010, 09:39 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #114 (permalink)
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I haven't taken this thread in a negative way. The frustration is of course the lack of application specific comparative data. As stated we need a controlled dyno test of the various sytems.
This runs into a mirad of problems, most significantly the definition of our application. I have built my engine around what I believe to be the most common upgrades for a mid-level CIS engine. That is my baseline.
Dyno testing these systems would be, pardon the pun, exhausting. You are talking small differences that are hard to see on a dyno yet easy to feel on the street. Driveability enhancement is difficult to see on a full throttle dyno pull. With each new system you would have to tweak the AFRs and be confident that the charge air temp remains the same. Not as easy as it sounds.
I do plan to do this type of testing when time permits. One thing I would like to stress is that I am not fixated on any one design just because I sell it. The designs must sell themselves. If I have made a miscalculation and find a design is substandard it will be changed.
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'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
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Old 01-15-2010, 01:33 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #115 (permalink)
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Quote:
Originally Posted by Speedy Squirrel View Post
Or an exhaust leak, or an air leak after the metering plate, or an offset to the O2 sensor due to contamination.
Most likely. Going lean because you have an efficient exhaust (no matter who makes it) with a turbo stuck in the middle (sorry, exactly in the middle), makes no sense.
Old 01-15-2010, 04:37 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #116 (permalink)
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Nothing was changed but the headers. The existing Euro system was in excellent condition with no leaks. The new ones have all new hardware and I've detected no leakes. There is no O2 sensor or smog equipment of any kind on my engine.
The headers were responsible for the change in idle mixture. Don't know why myself as I did not expect the change to be significant. These headers are obvioulsy vastly different in design than the J-pipe configuration that was replaced, we do know that much. You can hear the pulses hit the turbo at low idle like a cammed engine.
Don I would think you should hear this cammed sound with your headers as well. Have you not experienced this?
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'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
Brian B. (256)536-9977 Service@MKExhaust Brian@RarlyL8
Old 01-15-2010, 05:03 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #117 (permalink)
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911st: I know you enjoy the mental challenge of trying to understand things at a very high level of detail...I was not trying to hijack the thread, just for me personally the biggest thing that matters is what products are actually out there and how well they work.

I just see people saying what equal length is or what short length is and at the end of the day the only thing that matters is what the dyno says and whether the car is quicker or more driveable. To me the lean condition is EXCITING, it suggests progress towards a better flowing exhaust than a B+B for the same price. But we don't know for sure, and that is where the real research should be going right now IMHO. We all have a vested interest in finding out whether Brian's product is better on the dyno. We know it is better in quality.

Anyway I am not trying to hijack your thread. Brian says it best that we are all a bit frustrated by having to talk in theory about headers after all these years.

I guess what I am saying is what if Brian already came pretty close to the Holy Grail? That is exciting. We all want to be able to throw something onto our car to make it go faster. For a similar price as a B+B, I would rather have the system which dynos the best.

Also 911st, I don't think you personally ever made this into a thread of Brian vs. B+B, I understand that you like to think in theory about these things. It just becomes the elephant in the room when we talk about headers to compare the designs that are affordable. Companies like GHL have already gone under, so choices are pretty limited. Pretty much by default when we talk about headers anymore it is going to be Brian versus B+B.

It just seems clear that the last step in this conversation involves a dyno.

I apologize if I am jumping to the finish line and skipping all the theory behind headers, but I don't have the mental capacity to understand all the theory anyway. lol.
Old 01-16-2010, 04:53 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #118 (permalink)
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Quote:
Originally Posted by RarlyL8 View Post
I do plan to do this type of testing when time permits.
Given the course and length of this thread, it looks like it needs to be a business priority.
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Old 01-16-2010, 05:15 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #119 (permalink)
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Ha! Yes it may but boy it's gotta stand in line with the other business priorities or soon their won't BE a business. Funny thing about folks wanting their orders in a timely manner ...
Now I gotta go out in the shop and assemble some headers! The last batch is done and I've got orders to ship!
The very bottom line is that headers are a good thing, and mine are quality. Any other performance bump you get is a bonus.
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'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
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Old 01-16-2010, 06:51 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #120 (permalink)
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