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Old 10-11-2000, 04:43 PM   #26
stewartg2000
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jhamilton: i think you meant www.spomotorsports.com ... when i was looking at them this weekend you shoulda let me hear em ,, when are you going to be in beaverton next?

to all: the information i was given from scott (owner of spo motorsports) this weekend is that the new headers were redesigned for more clearance while shaving 4" off the overall length of piping, with sleaker bends. he had not dyno'd the header at that time however the old header was dyno'd at a 12hp gain, so these should be a little better, even if there is no additional gain over the 12 atleast they fit better and no rubbing.

nopi has placed orders for some i believe 15 sets, however neither spo nor nopi have them in stock for shipping. jhamilton works for spo and is running on the experimental headers, they are not going into production until this week. again, this is only information relayed to me from spo.
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Old 10-11-2000, 05:51 PM   #27
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Question

As CollinL mentioned, the way the picture shows it looks like the oil filter is going to be a problem to take out.
I hope I'm wrong.

JHamilton: Since your the only one with the new Borla design can you tell us if the header is in the way or not?

Thanks
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Old 10-12-2000, 05:35 AM   #28
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Just speculation, but it looks like a perspective thing. The oil filter is probably pretty close, but not actually prevented from coming off. Just don't do it right after you've been running the engine for awhile. BTW, is it me or do the welds look a tad sketchy?
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Old 10-12-2000, 06:55 AM   #29
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The oil filter clears good. The welds on the header are good and there are added weld for extra strength. I have had the header on for 1200 mile and have not had any problems.
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Old 10-12-2000, 07:06 AM   #30
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Whats the inner diameter of the headers?
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Old 10-12-2000, 07:13 AM   #31
Corey
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JHamilton,

OK, so now that you have replied to all the other questions, can you post the dyno charts? If you are not at liberty to, then just tell us...

Thanks,

Corey
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Old 10-12-2000, 04:59 PM   #32
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Then what Headers would you recommend? There arn't to many solutions (for the RS)

[This message has been edited by Dan_E (edited October 12, 2000).]
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Old 10-12-2000, 09:05 PM   #33
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I actually applaud Borla for what looks like abetter header design. The pipes look like they may work out better, at least CLOSER to equal length. It looks like a much better design than the old one. why wouldn't it be able to run a turbo? I'd be interested in seeing who tries that new one with a turbo. N/A will probably still be fun too :}. Where do I send my credit card info?
Kevin, Joel, where are you?


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Old 10-13-2000, 12:16 AM   #34
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Question

Word was that the old Borla header cannot handle the heat of a car running with a Turbo. Does this apply to the new header as well? Or has there been some material change to increase the strength?
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Old 10-13-2000, 12:52 AM   #35
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uh...I don't think that you'd run a turbo with those N/A headers....
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Old 10-13-2000, 03:25 AM   #36
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Would it be possible to fabricate/attach a heat shield to these headers?
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Old 10-13-2000, 06:27 AM   #37
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I would bet you could mount a heat shield without too much trouble-- do you think that the floor would get hot? Hmmm maybe a jet coat would be a more elegant solution-- can you ceramic coat stainless?


Dan_E: If you're going the turbo route, SYMS makes some nice headers, but you're right, borla and an aussie company MRT(?) seem to be the only options for normally aspirated 2.5 applications.

rj
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Old 10-13-2000, 07:05 AM   #38
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The whole thing is welded up eh?...one piece? How big was the box it came in?, remember how much it weighed?

Any comments on low-end torque?
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Old 10-13-2000, 07:35 AM   #39
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ENGINE PIPES / EXTRACTORS
SUWBE110 Exhaust manifold extractors. Links from exhaust ports on heads to
start of new exhaust system. Including Cat converter. Only with MRT
system. Wont fit std exhaust
$445
SUWBE110A Exhaust manifold extractor type pipe. Links from exhaust ports on heads to start
of new exhaust system. NO Cat converter. $264


$445 AUD = $238.88 US and $264 AUD = $141.72

Shipping is more, of course. If anyone bought just these bits, they would know or else MRT can tell us. ANY custom exhaust shop should be able to build what is needed to connect these items to whatever else we want to run.

"paste" does not seem to be an option so I cannot put the picture of the MRT pipe here, but it is on their parts photo page. It is straight rather than this round about Borla. I read previous threads from people who really like them.

Lets see.....
MRT - cheaper, straighter
Borla - expensive, curves around a 90 degree bend and blocks the oil filter.

Am I missing something? If the Borla is really the better option, I'm in, but...
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Old 10-13-2000, 07:43 AM   #40
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Are you referring to this one?
<img src=http://www.mrtrally.com.au/performance/photo/mrt169.jpg>

Not sure if this is the same system or not.
<img src=http://www.mrtrally.com.au/performance/photo/mrt077.jpg>

Primaries are very long... May not have very good low-end torque with that setup. The site says it's designed for the 2.0L naturally aspirated motor so I am doubly suspicious about it.
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Old 10-13-2000, 07:49 AM   #41
Rich L
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Exclamation

The 1 problem is that your not legally allowed to move the cats from the stock configuration, thus the MRT set up IS illegal and not the Borla set up!
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Old 10-13-2000, 09:14 AM   #42
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In terms of legality, don't you think that as long as the inspectionn station saw a cat there, they'd have no idea what the original position was and therefore pass you no prob?
For this reason I would think that the MRT headers would work just fine in terms of getting that little sticker on your windshield

rj
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Old 10-13-2000, 09:30 AM   #43
kar250c
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Actually MRT has the same option under 2.5 non-turbo includes US spec. I am concerned about the low end torque too, but I seem to remember other folks on the board saying "there was no loss anywhere". Correct me if I am wrong.
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Old 10-13-2000, 09:54 AM   #44
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Longer primaries actually help in retaining torque. Short primaries are what make you lose torque, but are essential for big hp. Think of it like this:

Each exhaust stroke produces a pulse of exhaust gas. Put several cylinders together and you get several of these exhaust pulses, put them together and you get a wave. These waves create a pressure differential inside the exhaust pipe, thus creating a small high-pressure area in front of the wave, and a low-pressure area immediately behind it. So, each wave helps pull the wave behind it, and push the wave in front of it. This is essentially called "Exhaust Scavenging". This is definitely a good thing since by scavenging the exhaust, more exhaust can be 'pulled' out of the cylinder, thus allowing more air/fuel to enter creating a denser charge and therefore more power.

By having long primaries, the exhaust is constrained, and the exhaust waves can be held closer together, thus helping pull each other out. However, at some point(high rpm), the exhaust waves can not pull the exahaust out fast enough, and due to the restriction of the longer primaries, they cause excessive backpressure. Short primaries eliminate this problem because there is essentially no restriction to the exhaust gas. But, since they do not restrict the exhaust gas, the exhaust pulses or waves are not as efficient, and thus can not scavenge the exhaust as well, resulting in less dense air/fuel charges, and thus less torque.

This BTW, is the reason the mega hp dragsters use very basic upturn pipes for exhaust. Due to the sheer volume of exhaust gas and the added benefit of the blower and high rpms, they do not require any exhaust scavenging. The idea for them is to dump as much air/fuel into the engine and then let it out as fast as possible so another charge can go in.

Hope this is clear.

In regards to the topic at hand...
I really can't see the benefit of the Borla headers aside from an increase in noise. They may have some minor benefit, but I don't believe they are an efficient design. The primaries are of unequal length. The exhaust gases exiting the left side of the engine (according to the pic) must travel several more inches before entering the CAT. This is what can be termed as an unequal length header. Compare this with the stock setup, and you can plainly see the stock setup has a much more equal length distribution. The only downside to the stock manifolds is the size, and the way they blend into the CAT. Other than that, they are a much better design IMO. Besides, you don't want to be heating your oil in the oil filter via a hot exhaust pipe. The whole idea to oil is to keep the engine lubricated, and to cool vital internal parts. By heating the oil, you're doing yourself a disservice.

Dave
'00 Subaru 2.5RS Sedan
'00 VW Passat GLS 4Motion
'72 Datsun 240Z




[This message has been edited by Catfish (edited October 13, 2000).]
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Old 10-13-2000, 10:36 AM   #45
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Guess I got that backwards...

Good point about the oil filter and the heat. However I disagree that the stock manifold is better just because it is closer to equal length. Look at the L + R collector! The right side merges at a *very* bad angle. Each side pair also merges in a not-so-good (but typical OEM) way.

(pic snagged from the vendor forum borla topic-- OE header on the right, old borla design on the left)
<img src=http://216.242.153.40/MembersList/UserPics/1358/Dsc000101.jpg>
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Old 10-13-2000, 11:52 AM   #46
1.8L
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Hello,

Oh, okay, I'll post something. Exhaust scavenging is what got me Exhaust waves in the same tube don't pull eachother because the timing is off. It's 4 strokes later that the next pulse comes and the exhaust waves are moving so fast that the low pressure zone is long gone. However, when you have more than one cylinder working together, then ideally, you set up the headers so that the low pressure zone behind one pulse passes by the joining area of two pipes right before the high pressure zone of the pulse coming from that cylinder. In that way, the pulses from each cylinder get pulled by another pulse and pull another one in turn. With 4-into-1 equal length designs (must be EXACTLY equal length), you get just this since each cylinder exhausts at a slightly different time than the others. At the junction, you get one pulse at a time, one after the next. With this type of setup, you get great scavenging at all rpms! However, the tube lengths are important because the pulses slow down drastically and lose a lot of energy the further they go. So, too long and you lose scavenging because you stop having discrete pulses.

However, it is possible, with careful engineering, to design a "tuned-length" exhaust where the pipes are different lengths. What you do is, knowing the exhaust pulse speed, make the tubes of such lengths that pulses meet at junctions at just the right time to scavenge eachother. This type of tuning is pretty limited in rpm range, however. You can design the tuned length around a specific pulse speed... Note that pulse speeds don't change much over a range of rpms, so a tuned length header might be "tuned" for several thousand rpms. In that way, "tuned-length" headers can be just about as effective as equal length. And more importantly, in a situation like the flat-4 motors where it's pretty hard to make a 4-into-1 design that is both equal length and not too long, the tuned length exhaust can often be BETTER than the equal length setup.

BTW, since Gary mentioned my name I might as well respond to what he wrote - "closer to equal length" means "not equal length" and so means nothing at all Either the headers are tuned correctly to aid in scavenging, or they are not. Either they are exactly equal length (at 6000 rpms, the pulses are coming so fast and close to eachother that I bet "exactly" means within a tenth of a millimeter - ie, less than one one hudredths of an inch in difference of length).

It is, after all, a science, not a guessing game - something that some of the aftermarket doesn't get.

I'm not saying anything about the Borla design or the MRT design. If Borlas is not tuned correctly, it might be worse. If MRTs is too long, it might be worse (btw, mrt is still 4-2-1, so you don't get ideal pulse scavenging anyway). There's no way to know without seeing full engineering schematics, or more simply, two dyno runs on the exact same car with just an exhaust switch.

Joel
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Old 10-13-2000, 01:12 PM   #47
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I'm going back to the post on moving the cat. When I last had my exhaust inspected in MD, nobody looked at anything under my car. They connected a hose to the exhaust and ran the car up to highway speed. That was pretty much it.
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Old 10-13-2000, 01:20 PM   #48
Overtime
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What an educational post. Thumbs up to Catfish and Joel for explaining this stuff!

We always talk about "equal length" headers and "poor designs" but it's nice to see some of it explained for once.

Fortunately for me, in NC, there's no visual inspection of the cat. I'm leaning towards the MRT setup for that reason...looks like it's optimal for low-end torque.
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Old 10-13-2000, 01:49 PM   #49
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Hello,

Re moving the cats - yeah it's illegal to move them and it's illegal to replace them with higher flowing versions even if such replacement lowers emissions. Stupid laws, eh? It's illegal per Federal laws, not state laws, so regardless of whether the state inspects them or not, you can be cited for such movement or replacement at any time.

But then again, it's illegal to speed and how many people here don't ever speed? For that matter, the cost of a good speeding ticket is about the same as the cost of a cat-citation. So think of it as a risk-cost-benefit analysis

Of note, Scott from SPO posted in the Vendor forum that the headers are pending CARB approval. That's great news. With the headers and a stock cat, the car will actually be 50-state emissions legal. With the headers and an aftermarket cat, the car will appear to be 50-state emissions legal - to the point that most inspectors probably won't know any different. They'll look at the headers, see the EO number, and be done.

Joel - who is, of course, not advocating doing anything illegal.

P.S., re turbos. Better flowing headers are never a bad thing for turbos. Since the Borla headers end in the same place as the stock headers, they can be used on turbo systems. The problem, in the past, has been that the weight of the turbo is supported by the headers at the headers-to-head bolts. That's a lot of strain. The stock EJ20 and EJ22 headers are bolted to the engine in several locations to provide additional support for the turbo. At any rate, the weight of the turbo seems to be supported just fine by the stock headers, but seemed to be cracking the old Borlas. Hopefully, these will be better and will not crack under such weight.

And if they are tuned length and the tuning was done correctly, then the increased exhaust velocity (due to scavenging) will result in faster spool-up, less backpressure, lower exhaust temps, less detonation, etc etc etc.

Joel
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Old 10-13-2000, 04:28 PM   #50
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Smile

Hello,


Sev - 2
Joel - 0


-sev
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