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benefit from aftermarket headers??

Hi all
for a 89 model I already have a k27 and BB mufflers would my car benefit from ghl headers?if so how much Hp am i looking at?
Thanks
Old 10-29-2009, 03:53 AM
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From what I've heard, GHL has closed down (the economy sucks). That said, a set of headers will make a big difference. It will help the boost to come on faster and maybe stronger. A lesser bar spring is sometimes required. Make sure you get one with a larger pipe from the collector to the wastegate to prevent overboost.
Old 10-29-2009, 05:43 PM
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You won't have a problem controlling boost with a set of these.
Headers are enablers. They don't add much HP but allow everything else you have to work better. Mine are equal length which helps off-boost torque. Night and day difference in driveability.

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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 10-29-2009, 06:40 PM
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I live in Canada and need heat .I was told the later USA cars has good headers is this true compared with the early USA cars?
Old 10-29-2009, 07:17 PM
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That is true. The '86-'89 USA 930 used the same exchangers as the Euro cars.
My headers will have heat exchangers soon.
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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 10-29-2009, 07:50 PM
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Just my two cents.

The GHL style system is just one of the popular "shorty style" headers.

In my opinion, on an 89 the biggest bang for the buck is the muffler, turbo, and then inter-cooler.

There is some efficiency available from headers in terms of reduced back pressure and increased power but for most it will be nominal compared to the later HE's.

I am suspect that a significant amount of the HP gain many find from aftermarket "shorties" actually comes from increased boost that is a result there wast-gate design which seem to increase the actual level of boost delivered. I have heard some reports of even triggering the over-boost switch when changing to a new system which is why I suspect this.

In my opinion we should not count the power that might come from a boost increase that is more a result of an increased effective boost as we can get by adjusting our boost levels ourselves.

To put some number to this, on a 300-360hp motor if boost is only bumped from
.8 to .85 bar that could be about 8-10hp.

One tuner quotes 40 hp from the headers alone. I suspect that is when stepping up from the early restrictive heat-exchanger system. I suspect for a later system it might be more like 5-10 from better efficiency and then about 10-20 from the higher boost that comes with the shorties. However, this is just an almost educated guess.

An inter-cooler is probably about 20hp from the lower restriction is makes and the increase in air density that comes from lowering of effective intake tempetures. However, it allows higher boost which could be good for another 30-40hp or so.

The other increase most notice from shorties is a faster boost response. This comes mostly from the reduced amount of volume that comes with a shortie system. Some have concluded that we also get some level of benifit from the coliding of the exhaust events that come from a non-equal length system. The thought be it creates waves of higher peak pressures that can better accelerate the turbo. However it happens, with the shorties boost comes in sooner.

Thus, I suspect that updating to a shorty system might reduce boost time by about 100 to 300rpm and get you another 10-15 HP in true gains.

It might be worth adding that there are also solid gains to be made in HP and boost response from dialing in one's AFR's and ignition values.

I have heard of owners of well tuned 930's that have ben able to get to full boost by 3k rpms with the later stock HE's and a k27-7200. Also learned of one tuner that claimed 600 plus hp with the stock HE's. Thus, there is nothing wrong with your HE's.

Not an expert, just what I believe so far.

Last edited by 911st; 10-30-2009 at 08:00 AM..
Old 10-30-2009, 07:55 AM
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thanks for the great explanation
Old 10-30-2009, 08:46 AM
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You already have an aftermarket muffler and K27. The question was can you benefit from adding headers (over the stock heat exchangers).
The direct answer is yes.
Bang for the buck is a different issue. The stock (free) exchangers are adequate but not optimal.
A good intercooler will run $2000. This will allow you to safely raise the boost level to 1.0bar for an increase of ~25hp at the most.
Headers cost about the same and will increase power about the same with zero added load on the engine. Well designed headers will greatly enhance driveability and throttle response and have no over-boost issues. I'm not a fan of the shorty headers for a street car, that is a simple cheap design with no tuning considerations and lousy heat. Street cars spend very little time on boost so it stands to reason that optimizing off-boost torque should at least be a consideration if not the focus.
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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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Last edited by RarlyL8; 10-30-2009 at 09:00 AM..
Old 10-30-2009, 08:58 AM
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Quote:
Originally Posted by ertech View Post
I live in Canada and need heat .I was told the later USA cars has good headers is this true compared with the early USA cars?
Like Brian and Keith said the the '86-'89 USA stock headers are the same as the Euro headers that work well as they are but are large and heavy.

The early USA cars had something different that was terrible for exhaust flow. They looked like something off an old tractor from the early 50's... and were hooked up to engine case warping thermal reactors that came before catalytic converters.

Headers with no other change to the motor are usually good for 5-10 horsepower improvement and some weight loss in the back while looking nicer, but they really shine and make gains in power when you do all the other hot rod mods to increase air flow into, through, and out of your air pump/engine while injecting more fuel into the increased air flow.

Brian's word "enablers" is the perfect short description.
Old 10-30-2009, 09:12 AM
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If i was in the market for a set of headers i would buy Brian's in a heartbeat! I'd be on his case for a solution for heat though. But i don't know of any other headers out there that are anywhere close with design being equal length in every way, fitment ease, retaining stock parts, great wastegate circuit etc etc. No brainer IMO
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Old 10-30-2009, 09:20 AM
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Brian,
Will your heat solution in the future retrofit to the headers you sell today? If one buys headers now can they add heat later when you complete that project?
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Old 10-30-2009, 09:31 AM
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Yes Jon I am certainly under the gun to get those heat exchangers going. Winter is around the corner and I need heat too!
Yes Kirk the exchangers will bolt-on in the field. That is a design requirement to give folks the option for heat after the fact or if an exchanger is ever damaged. It also makes installation of the headers a lot easier.
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Old 10-30-2009, 10:01 AM
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Brian, winter is already here in Colorado... 2 feet+ of snow out my front door.
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Old 10-30-2009, 10:35 AM
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Quote:
Originally Posted by 911st View Post
Just my two cents.

The GHL style system is just one of the popular "shorty style" headers.

In my opinion, on an 89 the biggest bang for the buck is the muffler, turbo, and then inter-cooler.

......
Canada and also Norway has colder climate that mid/south US.
Will a bigger intercooler make that big of a difference?
I would rather use the bucks on header than intercooler...

Am I wrong here?
Old 10-30-2009, 11:22 AM
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I have ordered a pair of Brian's headers and dual-out muffler, and am hoping to get them shortly. I also emphasized the heat point with him . Had my car out today and I had the heat on (NY), after I fixed the little plastic clip that holds the arm to the cable under the autoheat deal.
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Last edited by gsxrken; 10-31-2009 at 06:56 AM..
Old 10-30-2009, 11:31 AM
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These very expensive and no longer made or available MODE headers made by Bob Holcomb had heat exchangers on the secondary tubes.

The wastegate pipe on Brian's headers is located differently but maybe theres some way to fabricate something in stainless like the ones in this picture that are like a clamshell or something and the 2 halves can be clamped onto the headers in a way that they won't buzz from vibration using aviation grade T-bolt clamps.
Old 10-30-2009, 12:09 PM
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Quote:
Originally Posted by RarlyL8 View Post
... I'm not a fan of the shorty headers for a street car, that is a simple cheap design with no tuning considerations and lousy heat.

Street cars spend very little time on boost so it stands to reason that optimizing off-boost torque should at least be a consideration if not the focus.
Brian, I love your headers and if I was in the market at this time they would probably be my first choice.

However, I would like to balance your comments with a few thoughts.

In principle, shorties are better for a street car, equal length is better for a track car, and stock late 930 HE's are better for heat and lack of maintenance issues.

However, quality design can bring difference in all basic approaches closer to together. Still, if all approaches are optimized, the shorties are going to get us to boost onset sooner and the equal length design in most cases is going to be more effective at getting gross exhaust out of the car for more HP.

As most "non stock" 930 turbo owners are after power, an equal length design will be the most in keeping with this. Add a clear quality advantage and this is a winner without any additional benefits.

As to pre-boost tuning, from my knowledge so far, there is not much tuning that can be done to any part of the exhaust before the turbo that will help in any significant way with efficiency in the area before boost onset unless there is has been gross mistakes made.

With our low overlap cams and the back presser imparted by the turbo, even at idle, there is not any significant opportunity to tune the exhaust to create any meaningful scavenging effect from off idle at say about 1250rpm to boost onset at around 1700-2200 (depending on one's set up).

If we are in need of increasing the power in the pre-boost area we would probably better look for opportunities from things like an increase in displacement, increase in compression, cam design, less back pressure from the turbo and or muffler, and or by optimizing AFR & timing among a few other esoteric things like manipulating CP with acceleration and keeping the BOV open as idle and cruse.

I am not a big fan of shorties as I believe they misrepresent there true benefit which is reducing boost response by maybe a couple of hundred rpms over the late 930 design. Further, I suspect they overstate the increase in HP that comes from improved exhaust design when much of it probably comes from higher boost that seems to be a product of there waste-gate design.

However, they are a great asset to the 930 community as is your new long tube system.

Again, I believe that in principle:

Stock late HE's are a solid system is best for heat, and will require less maintenance than most any aftermarket choices.

Shorties are best for reducing turbo lag with there reduced volume that is more quickly pressurized. And--

True-Equal-Length headers are best for increasing efficiency at exiting exhaust and should best contribute to mid and higher HP levels. I might add some believe they also contribute to more equalized heat at the exhaust valve.

However, in the absence of true arms length testing, we will never truly know.

Last edited by 911st; 10-30-2009 at 01:09 PM..
Old 10-30-2009, 01:06 PM
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Sure you will know. Drive a mildly modified 930 with stock heat exchangers. Now swap out to shorty headers and drive the car. Now swap to my headers and drive the car.
I've done it. There is a difference. My car now drives like a 3.2L Carrera until the mid-2000rpm range when boost hits and the tires break loose.
There is more to the story than simple tube length. Volume, transition, merging and velocity are key. Turbo selection and cams are a huge influence in driving characteristics.
It is difficult to see improved driveability on a dyno but I plan to do just that when my car gets back on the road.
Heat exchangers will not be an after thought. I need real heat not this luke warm crap that most aftermarket systems call heat. When I DE the car in January with the windows down and have to turn the heat down I'll know we have reached our goal.
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Old 10-30-2009, 01:55 PM
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Quote:
Originally Posted by totle View Post
Canada and also Norway has colder climate that mid/south US.
Will a bigger intercooler make that big of a difference?
I would rather use the bucks on header than intercooler...

Am I wrong here?
A larger intercooler in my opinion dose three things.

First it dose cool the charge air and gets it closer to ambient than a stock IC when on boost. Even with the same level of boost this can get you from 20hp to 35hp depending on the car and the expert's opinion you source. When Porsche built there 91 3.3 Turbo the principle change was in improved intercooler. With this they raised there HP quote about 30hp I belive.

Secondly a larger IC makes for less air flow restriction. This might not make much difference at stock or lower air flow levels but at increased levels less restriction on the intake side may keep one from losing efficiency/ VE at higher air flows.

Third it allows one to more safely run more boost. In theory, if one goes from .8 bar to one bar one could get up to 11% more power if efficiency's are not lost elsewhere. (2bar/1.8 bar= 111% or an 11% increase.) Thus a motor with all the right mods to make 360hp at .8 bar in theory could make about 400 at 1 bar
(360/1.8 times 2.0=400).

For compairsion I suspect headers in my un-expert opinion are going to be good for up to maybe 10-20hp over your late HE's with no increase in boost. This is worth considering.

Headers (shorties) can reduce lag which is very appealing to some and often becomes the deciding factor.

It should be noted that things like you intake ports size, cams, turbo, and fuel capacity will become limitations as to how much HP you can safely make of if you will get the improvement hoped for. Thus, going from 360 to 400hp might be supported by the math, however these restrictions will likely make it less.

I belive I still have not answered your question.

The factory choose to improve the intercooler over the exhaust when they needed to bump HP. An intercooler will alow you to run safer. An intercooler will alow you to explore higher HP throught increasing boost.

In the end, it is a personal choice and should be part of a biger plan that you have decided on so you do not do things twice.

In the end you will probably end up with both. For me, if I had to only have one, I would go with an better IC.
Old 10-30-2009, 02:19 PM
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I want to mention that I have B&B headers with heat on my car and the heat is extremely hot.
I don't know did GLH headers have lukewarm heat? Never tried them out so I don't know.
The entire length of the header primary tubes right up to the collector on both sides are enclosed in a heat exchanger box and it heats the air blowing through in a big way.

Yeah, I live in S. Florida but when the large cold fronts blow all the way down here in the winter it often gets into the low to mid 40's at night and I've driven my car at night when it's like that and the heat is really hot from the B&B's.

My footwell blowers work and my feet and the rest of the interior will get too hot if I don't turn the fans/autoheat dial down.

Some of the hot air also comes out of the AC ducts when the heat is on and I leave a little 1"diameter analog thermometer in the left side duct because I like monitoring my AC duct temps since I've put alot of time and money into modifying my AC.
Anyway, I've seen 195 degrees coming out of the driver side AC duct and thats not lukewarm.
You'd think the plastic dash vents would melt or deform at that temp but they don't.
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