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What to expect from aftermarket headers????

I have had a beautiful set of GHL headers (w/heater boxes) sitting in my attic now for 3 years (impulse buy). I have not installed them because I have questioned if the factory 965 exchangers are nearly as good.
What should I expect from installing these. Here is a description of my car.

1982 911sc narrow body @2675 lbs with out me in it.
Engine is a a factory 965 3.3 Turbo S engine (rated @370hp)
The turbo S engine has different cams and heads. I dont recall if its the same turbocharger but recall its a K27 7200.
I added a modified fuel distributor and run the boost at 1.2 bar with excellent a/f ratios and exhaust temps.
Aside from the fuel distributor the entire engine is stock. Of course the 965 muffler and cat were swapped out for a large single outlet stainless B&B muffler. Wastegate has an open down pipe.
The transmission is a 1987 G50 box with very short gearing.
Full boost comes in around 3000 rpm with current configuration.

Will I get any worthwhile reward from installing these GHL headers?

Kurt Williams

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82 SC w/965S eng and G50 6:1 hp/w ratio
72 911t 2.6 twin plug and 72' 911t 57k orig 1 own miles
65/66 912 1 owner 76k orig
01' Aston Martin DB7 V12 Vantage Coupe 6spd
Old 10-30-2010, 08:25 PM
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You can expect the following from aftermarket headers;

The Good
1.) 200-300 RPM sooner with the onset of boost(conservative est.)
2.) nicer sounding exhaust
3.) weight reduction (10 lbs sound about right guys?)

The Bad
1.) Headers don't last as long as the factory heat exchangers (expect 5-7years life exp.)
2.) You going to see some boost overshoot with the GHL's, therefore I would not recommend a 1.2 BAR spring in this case. Go with the 1.0-1.1 BAR spring for safety's sake and to stay within the 1.2 BAR limit you built into your fueling system.

Now the B&B muffler.......
There have been reports from others here on the board that the B&B muffler is somewhat restrictive. Maybe Rarly8 or Ben of M&K can chime in on this comment. If true, you might want to consider going with a less restrictive, nicer sounding muffler. Though, as you can see from my signature, I have a B&B system on my 930 and I like the sound of it. Wish I had done more research with others on the board here before buying the B&B muffler.

Good luck. You have the makings of a very nice rocket!
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'85 930 Factory Special Wishes Flachbau
Werk I Zuffenhausen 3.3l/330BHP Engine with Sonderwunsch Cams, FabSpeed Headers, Kokeln IC, Twin Plugged Electromotive Crankfire, Tial Wastegate(0.8 Bar), K27 Hybrid Turbo, Ruf Twin-tip Muffler, Fikse FM-5's 8&10x17, 8:41 R&P
Old 10-31-2010, 03:49 AM
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This is a good topic to start. A lot of people jump on the aftermaket headers for some reason or the other (no offense to those dealers), maybe the sound, weight reduction and a bit of boost early on. It is interesting to see the stock system put to the test on on some super fast cars. For instance, there is a 3.0 on Rennlist that uses the stock system with most everything else stock, and here is the dyno:





Then there is Micke's CIS monster at 600hp, same thing with the stock euro headers.

Cis monster

And another car on this forum runs low 11's in the quarter mile with the stock headers.....

Quarter mile results.

....so, yes, the stock header system is a good topic to discuss, as it certainly does not limit the power capabilities and, in some cases, may actually enhance it.
Old 10-31-2010, 04:18 AM
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Quote:
Originally Posted by WERK I View Post
2.) You going to see some boost overshoot with the GHL's, therefore I would not recommend a 1.2 BAR spring in this case. Go with the 1.0-1.1 BAR spring for safety's sake and to stay within the 1.2 BAR limit you built into your fueling system.
I use the stock waste gate spring and an electronic boost controller. Do you think it would still be an issue?

As far as the 300 rpm sooner boost I don't know if that will be very noticeable because my transmission gearing is very versatile and the right gear seems to always be there. I can see 300 rpm making a world of difference with a 4 speed but with the G50 im not sure its worth the trouble.

I do like the hp gain posted above but then those are not comparing stock 965 exchangers to aftermarket headers.
I enjoy being able to call my engine stock. Any other experiences out there?
btw I am not a big fan of my muffler and im open to suggestions. I will look into what else is out there. Could go for a different exhaust note anyway. Weight is my biggest concern.
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82 SC w/965S eng and G50 6:1 hp/w ratio
72 911t 2.6 twin plug and 72' 911t 57k orig 1 own miles
65/66 912 1 owner 76k orig
01' Aston Martin DB7 V12 Vantage Coupe 6spd
Old 10-31-2010, 05:33 AM
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You won't have a problem with the boost because of the electronic boost controller. The main advantage of it over a spring is its quick and easy adjustability. If you see more than 1.2 bar with the headers the only thing you need to do is to dial it down.

When you say 1.2 bar,... is it maintained through the entire rpm range? Or is it the peak boost and then it tappers down?. Can you detail us the boost charasteristic curve, please?

I ask this questions because 1 bar limit is regarded as the safe limit, but I can remember the same in the Mitsu Evo's world and discovered years later that it was very conservative thinking. I'm curious about your 1.2 bar.

What brand of electronic boost controller do you have fitted? I have an Apexi AVCR on my Mitsu Evo and all I can say it is a superb device. On my '92 965 I have a manual boost controler for the time being.

Last edited by DA VINCI; 10-31-2010 at 06:39 AM..
Old 10-31-2010, 06:02 AM
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Very nice package (even if I am a bit bias, ha!)

I am going to assume you do not want to spend money replacing some of the components listed but rather optimize what you have (from what you describe your turbo, boost level, and fuel head can be improved upon).

Please verify what turbo you have. The 965S did not come with a 7200. Also the 7200 is useless at 1.2bar and no fuel head mod is typically needed when using this turbo.
(I am working with a fellow right now who's performance has been destroyed due to being sold a modified fuel head he did not need).

Supporting HP and being optimal are miles apart.
The stock J-pipe exchangers will support a lot of HP but leave much on the table. You have the headers, by all means try them!! You will see lowered boost threshold and greater torque/HP. Down side is overboost due to waste gate tubing design.
Another down side is heat. The short tube "log" exchangers produced poor heat.
Upside is if you don't like the headers you can put the J-pipe back on. A no-lose situation.

Ditch the 1.2bar.
Any power you get from going from 1.0bar to 1.2bar is far outweighed by the risk of detonation and stress put on your engine. Headers alone will make up the power differential.

If you are interested in losing additional weight in the rear after adding your headers take a look at my mufflers. They weigh 12 pounds and come in many configurations.
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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 10-31-2010, 06:40 AM
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As an example, with an EBC you can probably boost 1,2 bar from 3.5krpm to 5.5krpm and then avoid going lean at high rpm setting 0,8/0,7 bar from 5.5 up to the redline.
Old 10-31-2010, 07:02 AM
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Do you have an accurate boost guage?

If it is a K27-7200 being run with a 1.2 bar spring it most likely hit 1.2 bar for a bit in the mid range and then boost will taper to about .85 at red line on that motor. Peak HP will probably be about 360rwhp.
Old 10-31-2010, 07:56 AM
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Quote:
Originally Posted by pjv911 View Post
I have had a beautiful set of GHL headers (w/heater boxes) sitting in my attic now for 3 years (impulse buy). I have not installed them because I have questioned if the factory 965 exchangers are nearly as good.
What should I expect from installing these. Here is a description of my car.

1982 911sc narrow body @2675 lbs with out me in it.
Engine is a a factory 965 3.3 Turbo S engine (rated @370hp)
The turbo S engine has different cams and heads. I dont recall if its the same turbocharger but recall its a K27 7200.
I added a modified fuel distributor and run the boost at 1.2 bar with excellent a/f ratios and exhaust temps.
Aside from the fuel distributor the entire engine is stock. Of course the 965 muffler and cat were swapped out for a large single outlet stainless B&B muffler. Wastegate has an open down pipe.
The transmission is a 1987 G50 box with very short gearing.
Full boost comes in around 3000 rpm with current configuration.

Will I get any worthwhile reward from installing these GHL headers?

Kurt Williams
Hi Kurt,

I can give you a first hand result, close to what you are asking but not exact. I dyno'd with a friend who also had a 91 turbo. The difference between our two Turbo's were I had a set of power house headers with B&B muffler running .8 bar and he was running a 100% stock exhaust but with a 1 bar spring. I made ~100 ft*lbs more torque then he did at 3k rpm. How much was due to headers vs muffler can't say.

The B&B muffler did eventually split on me and I had a Borla XR1 muffler fabed up ($250 and the local speed shop) and saw an increase in just under 30 whp. This has been a known issue for years and B&B came out with a "sport" muffler to address this.
Old 10-31-2010, 08:07 AM
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Jeff,

Did the other C2 have the stock cat/pre-muffler? It is not great for response.

Kurt,

They have to have made changes but I had the same finding as Jeff as to the B&B C2T muffler. I could not get past the 330's on the dyno with my B&B. One day I was curious so I cut it open. I found that the largest passage was smaller than the in and out pipes. I also went to a home built Borla as what was the thing at the time and on my next dyno picked up 30hp.

On my C2T with almost the same motor build as yours but with headers and an S2intercooler I also saw full boost at 3k with a new K27-7200. However it could not hold full boost at HP peak or beyond. Even with the EBC cranked up to 1.1 bar.

I could be wrong but I always felt the section after the turbo is the most important, then ignition and AFR values. I had my AFR's corrected to 12.2/1 through TQ and HP peak with a custom programmable WUR.

Still I suspect a header system can reduce exhaust reversion some for a bit of improvement in TQ right where most street cars can most use it.

As to some of the higher power claims, some are starting to believe that is more from the different style WG circuit that results in a little higher boost with the same spring.
Old 10-31-2010, 11:25 AM
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Quote:
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2.) You going to see some boost overshoot with the GHL's,
Respectfully, not everyone sees this - I don't, for example. My mechanical VDO gauge shows precisely the same overshoot behavior (1 PSI for less than ~1/4 second) with the GHLs and a K27/HF that it did with a 3DLZ and factory RoW headers.

I think the advice not to run big waste gate springs is very sound.
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Old 10-31-2010, 12:56 PM
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Quote:
Originally Posted by zcoker View Post
This is a good topic to start. A lot of people jump on the aftermaket headers for some reason or the other (no offense to those dealers), maybe the sound, weight reduction and a bit of boost early on. It is interesting to see the stock system put to the test on on some super fast cars. For instance, there is a 3.0 on Rennlist that uses the stock system with most everything else stock, and here is the dyno:





Then there is Micke's CIS monster at 600hp, same thing with the stock euro headers.

Cis monster

And another car on this forum runs low 11's in the quarter mile with the stock headers.....

Quarter mile results.

....so, yes, the stock header system is a good topic to discuss, as it certainly does not limit the power capabilities and, in some cases, may actually enhance it.
i am not really sure where i am going with this post, but maybe someone can help,...

i had a 04 sti,...very heavily modified, making around 460hp, with stock exhaust manifold (headers)...

there were a ton of companies that made "headers" for these cars,...alot of owners chose to port the stock manifold and stay away from headers due to the "cast metal" of the stock manifolds vs. the "stainless metal" of aftermarket, due to the heat being kept in better by the stock cast manifolds,..something about the hotter air moving faster? or being more dense? something along those lines,...

alot of guys with aftermarket headers would have to wrap the *#&$ out of them, or they would actually loose spool up time...

then brings up the topic of wrap, and fire haZard with oil and such...that is why alot of guys just stayed away from them,...

has anyone here had the stock manifolds ported and heat coated?
Old 10-31-2010, 01:03 PM
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I am not sure if this could be used as a valid strategy but Kurt might be kind of doing something I have wanted to try.

The goal being to achieve a boost management strategy where boost is tapered to live within our fueling and thermal limits. Usually this is done electronically.

As a point of reference check out the thread on the Monster CIS motor. He runs up to 1.2 bar early and tapers it back to .8 bar at red line. Therry (sp) also did this with his custom fueler and boost management system based on a Split Sec controller with good results.

The K27-7200 seems to be unique in that the hot side seems to be the limiting factor that kicks in and limits the spin of the cold side before it gets out of its deficiency range or stalls. Excess exhaust is diverted out the WG. At least that is what I think I have been observing.

As such, running 1.2 bar might allow the turbo to make a big mid range and its nature will be to taper boost as the rpms increase.

If we have a good intercooler like that C2Turbo dose and as long as we do not detonate, which our to fat on first boost should help with, this could work very well and be a natural fit.

Not your typical approach but would be interesting to look into.

However, put a big turbo on that thing with a 1.2 bar spring and it could be trouble.

Maybe just another crazy thought.
Old 10-31-2010, 02:34 PM
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I see 1.2 bar at the tell tale needle. Im too scared to take me eyes off the road when on the go. It is certainly possible that the boost is falling off as RPM increases.
Im not sure which turbo I have. My 965 S motor came from the Brumos' race team when the 3.6 came out for them in 93' they sold off the 3.3 engines. Mine has some special stuff (inside and outside) that is different from the standard 965 engines. Many engine components say "Supercar" on them. Btw I have no idea what Supercar means.
Last year I lost spark and the diagnoses led me to a relay type box under the seat. Turned out that it is my rev limiter. What was cool was the chip inside was modified and the board had jumper wires. The rev chip says 7700 RPM !!
As for which turbo I have? I would have to take another look because its been some time since I read the tag.
I know it sounds crazy but I have had my VDO 935 type (clock replacement) boost gauge read 1.5 bar and the power was too much for my clutch once past 60 mph or so. Below that the tires would give.
My clutch is what was recommended by Jim Patrick when I had him make the flywheel. He said its the same unit that was used in the yellowbird Ruf car.
At 1.5 bar the a/f ratio was still below 12.5 all the way through the rev range.
Lastly I can't say if the fuel distributor mod did anything because I had it done before installing the engine. I do know that I have serious decel flames at all times. Fuel mileage is around 14 mpg.
I think I will try the headers soon. Brian I will take a look at your stuff. Weight savings is very important to me. Da Vinci I will check to see which boost controller I have.

Kurt Williams
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Never drive faster than your gaurdian angel can fly.
82 SC w/965S eng and G50 6:1 hp/w ratio
72 911t 2.6 twin plug and 72' 911t 57k orig 1 own miles
65/66 912 1 owner 76k orig
01' Aston Martin DB7 V12 Vantage Coupe 6spd

Last edited by pjv911; 10-31-2010 at 03:31 PM..
Old 10-31-2010, 03:12 PM
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Last edited by 911st; 11-01-2010 at 06:13 AM..
Old 10-31-2010, 04:36 PM
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Wow, interesting build!

I doubt if it was there race turbo if it would be a 7200

There was a guy here that bought one of the Porsche/Brumos 3.6 hill climb motors.

It had shorty style headers and a big Garrett turbo.

Also, the turbo scavenge pump was plumbed back into the bottom of the crank case where the oil plug was.

Last edited by 911st; 11-01-2010 at 06:12 AM..
Old 10-31-2010, 04:41 PM
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Very interesting car and figures...!

A pic of the engine and the turbo could help...
Old 11-01-2010, 01:42 AM
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Greetings:

jeff91C2T- What year was your B&B muffler??? Dual?? How long & miles before it went?? What year did you hear about sport muffler change??

I got mine in 1994- Sounds great..etc..etc..Any markings that would indicate sport??

Thnxs

Walt
Old 11-01-2010, 04:58 AM
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Greetings:

jeff91C2T- What year was your B&B muffler??? Dual?? How long & miles before it went?? What year did you hear about sport muffler change??

I got mine in 1994- Sounds great..etc..etc..Any markings that would indicate sport??

Thnxs

Walt
Hi Walt,

B&B came on the car when I bought it back in 2000. Receipts indicated install in 98 as I recall. Muffler was a single outlet and the failure mode was separation at the ends with the stuffing material showing through. I used the B&B as a donor (for the ends) and fabed up the Borla back in 05. Search the boards and you'll find other posts with similar issues.
Old 11-01-2010, 10:49 AM
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Thnxs..
I was under my car this weekend tighting bolts, boost leaks,anything out of the ordinary.
Knock on wood with my BB-Dual. Not sure I want to start messing with mine. I could open a can of worms.

Walt

Old 11-01-2010, 11:08 AM
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