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Rocket Scientist
 
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Were you planning to reveal your business relationship with RarlyL8 at some point? I think it would be appropriate when discussing those products.

Quote:
Originally Posted by Jeff Alton View Post
The new "Loren" of the turbo forum has been found..... appears to know of what he speaks, but won't share what he knows and has some interesting delivery....

oh well, should make for interesting reading....
Old 07-07-2010, 10:38 PM
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Just to chime in here, even though I don't post much anymore - here are my thoughts.

Brian - you've basically duplicated the orginal 935 shortie with burns collectors in lieu of the type used in the 70s....congrats and well done. The flow being equal will yield greater torque (which is something I don't need) and the collectors will prove better scavanging due to flow properties making for a more efficient setup.

If anyone doubts this type of design, I beg you to ask yourself the question...if they ran on real 935s like this and ran around 900 horse, at an insane level of boost...who are you to say its not a good design and won't work? Step up and show me what you're doing and your header setup to break 1,000 hp.

Brian has done many a good thing for this forum and our cars - so kudos and keep it up brother.

Here's a shot at some 935 headers for my 3.8 jigged off a set that came from a 935...repost I know but it seems that a few people have lost sight of what is known and what works for these cars, there is always a more efficient better way to do it, but the thing everyone forgets is a phrase called "diminishing returns".

This setup will work for huge power, doubt it? Lets put our cars on the line together and run what you brung...I didn't spend almost $100k on a motor not knowing if it would work or not...and what Brian is giving the masses, is a chance to get in on the performance at a very, very modest cost to what goes into these.

Street or track, take it or leave it, but if you're out for big power, if you don't want to dig it, you'll always be watching tail lights. Cuz this type of theory and execution tie into more than just exhaust, but into the whole concept from induction through exhaust...old school is old true, but it was way ahead of its time and is still way ahead of where most on this board are at.

Just look at Pat Willaims Racing, they're proving it daily that the old school is still kicking a$$ at small discplacement huge output motors.

So give Brian the respect he deserves, the customer who ordered them the kudos for putting a package together that will power the looks of his car and overall for the good it does the community for getting our 930s out there to show the masses again, what we're all about.



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Old 07-07-2010, 10:38 PM
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I wouldn't take it as snobbish, nor does doing an exhaust the right way always cost more.

Personally, I am cautious about calling something an innovation just because it is different.

Quote:
Originally Posted by WERK I View Post
Finally!! Some sense has come from all of this.
I've seen the Bob Holcomb works-of-art, but good grief man, these things are built to a specific, limited application. Brian is a Porsche hot-rodder who loves these cars. If he wants to come out with a product that is better than the competition (FabSpeed, B&B, GHL, Schell or OBX for that matter) in this market, then more power to him!
Stop being "header-snobs" .....there's enough wine-snobs out there to cover any industry.

Finally, if there are truly engineers out there, then some of you have lost sight of our profession, INNOVATE!
Old 07-07-2010, 10:57 PM
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Less Mountain Dew, and your mom told me about the stack of Import Tuner mags hidden in your closet.

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Originally Posted by s_morrison57 View Post
Hey Speedy
Your opinion is like an A hole, everyone has one, are you marketing a better product than Brian, why not??? seems like you know everything, maybe you've been sniffing to much rocket fuel, You wanna dump on people then hit off topic, you'll get your butt spit out in a hurry, do you even have a P car or is your turbo on your mom's Kia. Sit back , shut up and read, maybe you'll learn something from the people that are really knowledgeable. The more you type the goofier you come across, Ya got any front wheel drive burn out pics to share?
Old 07-07-2010, 11:00 PM
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I'm not going anywhere, and I never attack any person.

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Originally Posted by cole930 View Post
I honestly welcome a good exchange of experiences, ideas, and technical opinions and I am sure everyone else does also. From some of his past posts it seems Speedy may have the background and knowledge to be a viable contributer to a good discussion on exhaust systems and his opinion would be welcomed and appreciated. But does anyone really think the way to start such a discussion is by making your first statement " The worst I have ever seen. Good for a laugh though " and then have the gall to whine about someone attacking him personally. Jesus man, you may be the greatest mind known to man but your social skills suck. Get your s--- together and come back when you can actually contribute something constructive because that's what we are all here for.

Cole
Old 07-07-2010, 11:04 PM
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Your's are way superior to the RarlyL8 design, and I would have to disagree with your statements on scavenging and torque.

I've seen Moby Dick in person at the Porsche museum. No RarlyL8 headers there. They are the usual Porsche design with the tubes each blending into each other, which is of course optimal for rear mounted twins. I'm sure they spent some time getting there. Must have been something back in the day...

Quote:
Originally Posted by Reaper930 View Post
Just to chime in here, even though I don't post much anymore - here are my thoughts.

Brian - you've basically duplicated the orginal 935 shortie with burns collectors in lieu of the type used in the 70s....congrats and well done. The flow being equal will yield greater torque (which is something I don't need) and the collectors will prove better scavanging due to flow properties making for a more efficient setup.
Old 07-07-2010, 11:48 PM
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What if the pipes were unequal length but were all multiples of the particular resonant frequency- what I mean is that the short tube is 1 wavelength, then the next is 2 and the long is 3 wavelengths. Would that allow some better packaging while still keeping the tuned rpm/frequency exhaust scavenging? Or is the wavelength/volume too big?
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Old 07-07-2010, 11:52 PM
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The 935 twin turbo headers are not a superior design for a street car.
Again, apples to oranges.
NONE of the design features in the 935 system are optimal for a sub 400WHP 930. I'll take that challenge any day. It would be cheaper in many ways for me to duplicate the short tube design of every other header system on the market. Equal length is proven superior and had been for decades. I didn't invent this. The data is out there for anyone to see. What I did was find the best design features for a set of street 930 headers and package them at a reasonable price.

Your theories do not apply to the street 930 application. I'll put my headers up against anything on the market. Bring it on.
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Old 07-08-2010, 05:15 AM
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I love equal length and twin turbo set ups. They are sexy as hell but do have a cost in several ways ( money, complexity, weight).

Just an opinion as understanding of exhaust theory seems to keep evolving.

A well designed single turbo can match a twin turbo system in response untill one gets to mega Hp levels.

Part of a good single turbo design is keeping the two sides of an even fire 6 exhaust mostly divorced from each other preferabley with a split turbine turbo on the single turbo system.

This mostly stops the reversion that is paticular to a common exhaust header that ties all 6 cylinders togeather in which two exhaust valves are then open at the same time which effects each other and premots exhaust reversion. This is the most significant advantage that remains a benifit of a twin turbo system. Keeping there from being overlaping exhaust events on the same manifold.

Yes, turbo headers are different than NA headers. However basic principles do seem to cross over.

Exhaust leaves the cylinder at about 70psi on all motors. On a turbo system the ressident pressure in the header at full boost might be about 10-15psi v a couple of pounds on a NA motor. This seems to slow down the speed of the exhaust but dose not keep good design principles from working to reduce reversion, back pressure, and gain some scavaging at some points of operation.

Thus I suspect equal length tubes on a turbo can probably be shorter than the 32-38" NA ideal and still offer more than just orderly exit of the exhaust events.

Collector design can be just about as important on a turbo. A good collector will aid orderly exhaust and reduce reversion.

No one seems to talk about the secondary tube's importance to a header system. It seems the secondary tube sizing may be as impotartant on a NA header than the primary tube dimension. I suspect a little length to a secondary tube on a turbo system will help to reduce reversion and help scavaging at some points. On a NA motor ideal secondary length seems to run in the 12-24" range and has a significant impact on the TQ band.

Brians twin set up here and his single both probably have better secondary tube demensions that most Porsche turbo 6 designs.

Is it perfict? I do not know. It sure looks like most good design prininciples have been included and no major mistakes seem to stand out.

I would like to see getting the wastgages out of the turbos if possable for increased effecency at the turbine exit, higher differental pressures at the turbine, and possably better response. Still it is a very nice system and should rock with the best of them.

Not an expert.

Last edited by 911st; 07-08-2010 at 08:28 AM..
Old 07-08-2010, 07:10 AM
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Damn I love this thread! All of you rock! Brian I am still in line for headers, but now you got me thinking twins. Augghhhh.....
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Old 07-08-2010, 07:18 AM
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Quote:
Originally Posted by RarlyL8 View Post
The 935 twin turbo headers are not a superior design for a street car.
Again, apples to oranges.
NONE of the design features in the 935 system are optimal for a sub 400WHP 930.
Perfectly stated, the 935 header setups are good for a very dialed in power band for the turbos being run with about 3k RPM everything outside is almost worthless. This is where Brian's setup comes in for the guys that use their cars on the street and want to IMPROVE the stock power and increase the band.

I think this is what some people are missing is that on the lower power cars, efficiency and flow is very important as you can't afford to waste the power.

Kudos brian
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Old 07-08-2010, 09:00 AM
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Quote:
Originally Posted by Speedy Squirrel View Post
Were you planning to reveal your business relationship with RarlyL8 at some point? I think it would be appropriate when discussing those products.
Planning to reveal?? I don't hide behind an internet name on webforums. I would think a fair number of people on these forums know who I am and what I am about.

But, since you asked, my business has sold exactly one muffler from Brian over two years ago, customer was very happy with it. I sent him the heads to use for his development as I bought them and they were junk (advertised as useable) and I had no use for them. That is how this community works, people contribute, maybe you should consider trying to do that for a change.....

Anyways, your turn now, time to reveal who you are and become a contributor instead of a commentator....

EDIT: in all fairness I do remember reading some posts you made regarding turbo numbers/identification that were helpful....
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Last edited by Jeff Alton; 07-08-2010 at 09:31 AM.. Reason: added content
Old 07-08-2010, 09:16 AM
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IMO:

As for comparing the 935's above against RL8 twin turbo headers above, the 935 header design is potentially more of a street header and Brian's design is potentially a better race header -- if sized properly.

The exception being the wast gate circuit on this set of Brian's twin turbo headers which is only really more of a street set up.

The 935 is more along to style of a direct short style header system and the RL8's are more like the factory race 993 EVO GT2 headers in concept with equal length primaries and some length to the secondaries to promote more ballanced cylinder savaging, temps per cylinder, and AFR's per cylinder.
Old 07-08-2010, 12:55 PM
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Quote:
Originally Posted by Flieger View Post
What if the pipes were unequal length but were all multiples of the particular resonant frequency- what I mean is that the short tube is 1 wavelength, then the next is 2 and the long is 3 wavelengths. Would that allow some better packaging while still keeping the tuned rpm/frequency exhaust scavenging? Or is the wavelength/volume too big?
That would work if you were tuning a guitar or a microwave guide ( I thought about your solution for a bit too), but then realized that rpm = frequency so you would have to tune for one rpm value.
You're an EE I assume ?
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Old 07-08-2010, 01:53 PM
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"the 935 header design is potentially more of a street header and Brian's design is potentially a better race header"

Just curious, what makes you state this as if it is fact? did you race 935's or work on any?

Have you or anyone dyno tested any of these headers back to back without any heat soaked intercoolers ahead of the test runs?

. . . didn't think so.
Old 07-08-2010, 02:20 PM
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I have no practical experience with turbos, but as i'm thinking of buying a 930 I have been doing some reading.

What I have gathered is that a primary length of 20 inches is a good start, diameter is a trade of between spool up and power.
Also you want the exhaust pulses to come as separated as possible to the turbo, that is what makes a twin-turbo spool faster; more separated pulses not a smaller turbine.

But maybe twin-turbos are becoming old school, with new engine management and anti-lag systems big single turbos might be coming back.

With a soft rpm-limiter at ~4000 rpm actuated by the clutch pedal you keep the right foot planted and when you clutch you cut the spark, limiting rpm dumping fuel through the turbo keeping it revved up, but much more gentle to the turbo than with retarded ignition. The throttle is wide open, nothing that slows down the compressor. While a big turbo i slow to speed up, its also slower to stop!
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Old 07-08-2010, 02:45 PM
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Quote:
Originally Posted by 9dreizig View Post
That would work if you were tuning a guitar or a microwave guide ( I thought about your solution for a bit too), but then realized that rpm = frequency so you would have to tune for one rpm value.
You're an EE I assume ?
EE No, that stuff scares me I am an ME

I was under the impression that equal-length scavenging effects only worked for you at a certain rpm range, anyway. At other rpms, they work against you. The "tuning" of the exhaust system tries to move these points and why there are flat spots and high power spots through the rev range.
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Old 07-08-2010, 05:16 PM
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Old 07-08-2010, 05:31 PM
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That has been done on the intake side in the past in some cases. Ever noticed different length intakes on a drag car or such?

The chalange is you need to be able to adjust the timing and fueling then by cylinder or you will leave potental on the table or be running closer to the edge on some cylinders. Not an issue if you have a Motec or such and can micro tune the car.

Bassically you get that with an unequal length stock system to a degree.

However, if your goal is to widen the TQ band you can also set up different parts of the motor to work at different rpms. For example, a cam that works best at 5000rpm, an intake that works best at 6000rpm, a turbo that is most effecent at 5500rpm, and exhaust that works best at 5200rpm or some such.

Line all components up so they are most effecent at the same time and you will make more peak HP but for a narrower range.

On NA rally or street cars the exhaust is more often tuned to be at its best at TQ peak. On a race car it is often tuned to be at its best somewhere between TQ peak and HP peak.
Old 07-08-2010, 05:31 PM
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If the lengths were all multiples of a wavelength, I thought it would have pulses at close enough to the same time as equal length. Particularly on a flat-6 with short primaries to a twin turbo setup. The issue would be viscous drag on the walls slowing down the longer runner, along with rejected heat.
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Old 07-08-2010, 05:40 PM
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