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Changing the headers on my C2S next weekend to the Porsche X-51. Changing only the headers..

I'm going to do the job on ramps. Can anyone give me a list of tools I'll need? I believe I have read the manifold torque is 17 pounds.. Is that correct?

As far as tools.. anything special? Open end wrenches? Swivels?

Good idea to spray the bolts the night before with WD-40 (or such) to free them up?

Any other tips or suggestions? I searched for a DIY but couldn't find anything.

Just want to make sure I don't have to stop half way and run over to China Freight for a tool..

As always thanks in advance to my Renntech brothers......

:renntech:

Edited by phillipj
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It's supposed to make a subtle improvement in mid range power and torque. No difference in sound and since they are Porsche they will fit perfectly with my PSE.

I acquired them for a very good price and the stock "S" headers are really poorly designed.

Even the aftermarket tuners admit they cant improve on the X 51 design (but they sure can charge a lot more money.)

Below are pics of the stock "S" headers (bottom pic) and the X 51. Don't have to have a degree in fluid dynamics to see which is the better design...

I said no mods on this car and look what's happening already.... B)

post-7267-1257544045.jpg

post-7267-1257544063_thumb.jpg

Edited by phillipj
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Can anyone tell me what they use to free - up the header manifold bolts? I'm going to change the headers next weekend and I know the bolts will be difficult to remove. WD-40? Something better?

Should I just spray it on the bolts the night before I plan to replace them?

Thanks !

Phillipj

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i recently changed my stock 996 headers to the 997 type. had no problems removing bolts but did apply some wd-40 the night before. used a 13 mm socket and torque wrench for the entire project.

i did not notice any performance change, just a slightly different sound but very minor. the 996 headers have longer primary pipes and maybe there is a little more low end torque. Not sure it was worth doing from a performance aspect. my reason for replacing the headers and cats was to eliminate vibration and it did. car runs and feels very smooth.

why do you think the stock headers are a poor design?

Edited by george996
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thanks for all the tips. The stock headers on the "S" are very restrictive. I have no idea why Porsche changed from the tried and true X 51 header and went for this design.

When my Dad was a chief mechanic (in the 70's) on what was called then "Group 6" (which is today the Le man series) he was involved in a very secretive Japanese backed open cockpit car called the "Shadow" I got to hang around the shop quite a bit and got to know the engineers.

I was fascinated by the guys who designed and fabricated the headers. Even though I was kid they taught me a lot. The bottom line is the more restrictive the header the worse for performance. You can look at the stock "S" header and see how the exhaust gases from the 3 cylinders will merge in one small area then have to fight there way out. That is not an efficient design.

I have been around a lot of race cars from Top fuel dragsters to Indy cars to Lola's, 917 Porsches and such and have never seen a header designed like that. All internal cumbustion engines work on the same principal and the Porsche Boxster engine is no exception.

Porsche must have had a reason but I have no idea what it was.

Thanks for tips and I can wait to feel that extra 100 hp gain :rolleyes: :lol: :jump:

:cheers:

Edited by phillipj
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13mm socket will fit the bolts on the crankcase. Probably won't need WD40 or anythng like that on a car as new as yours. I had no trouble on my 2000 996 that has been through 8 slaty winters. The bolts that hold the headers to the cats could be more difficult. On my car these were really rusted in. Again, on your newer car they should probably come off pretty easy.

Are you missing the old 996? :P

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For the sake of discussion...

I keep seeing posts that condemn the 997S headers, but I'm not yet convinced that they are as bad as everyone believes. Most of the posts seem to indicate that they LOOK like they are restrictive, but here are a few things to consider.

1) Porsche engineers work very hard to coax the maximum amount of power from these six cylinder marvels, so why would they intentionally reduce horsepower on their higher end engine by replacing a more efficient header (X51) with one that is less efficient? Doesn't make sense.

2) People keep saying that the S headers are restrictive because the three tubes go through the same restrictive point. This would be a problem if all three cylinders were evacuating gases AT THE SAME TIME, but imagine the flow through this header with each cylinder exhausting gases in SEQUENCE. Under those conditions you might actually set up a continuous high velocity flow (taking advantage of the restriction to impart a venturi effect) that would help to suck the gases from each cylinder. If this is the case, we should be removing our X51 headers and replacing them with all of the discarded 997S headers. :huh:

3) I agree that an an obvious design flaw present in the S headers is that the tubes are not of equal length.

I don't have a CS (I have a C4), but if I did, I would have to see a decisive dyno comparison before I changed headers because the risk is that you may actually be reducing power by swapping headers.

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Point taken.

I will agree that there is a chance that the X 51 headers may reduce power. I put cat bypass pipes on my old 996 and it killed the low end power and torque.

I feel confident in the swap to the X-51's because several tuners that I know have blessed the swap when I mentioned it to them. I tend to disagree with the argument that "if Porsche could have designed a better header they would have" as baloney.

They saw a chance to cut costs and that's what they did. It's a bad design.

Look at every header from the 993, 996 and 997 (including Turbo and GT3) and not one is designed like the 997-1 "S" header. The 3.8 is basically the same freakin engine as the 3.6.(which has the X 51)

So Porsche came up with this awesome header for the 3.8 'S" but decided not to share it with the other variants??? I don't think so.. Not to mention the 997-2 "S" has a completely different header.

I will let everyone know if the car runs better and I need a DIY anyway.

I feel better now.... :D

:renntech:

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All good points.

>> I will let everyone know if the car runs better and I need a DIY anyway. <<

I read somewhere that you would have to add something like 15 HP to a 200HP engine in order to notice the difference in the seat of your pants. I have no idea if that is true, but I have alway taken with a grain of salt the guys who say, for instance, that they changed to an aftermarket air cleaner and now their car feels a lot better. Point is, you may or may not get an HP gain, but IMO it is unlikely that you will be able to feel the difference. That is why I was wishing for some Dyno data. GL

Mike

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You are correct I probably wont notice anything... But as much as I want to let the car alone I can't. I got a very good deal on the headers and it will be a fun project. I may have them polished just to create a nicer appearance.

To get the full effect of the headers I would have to do all the X 51 components (airbox, throttle body and manifolds.) Basically the Porsche "powerkit" without the cams and heads.

Unless those fall out of the sky (they are very pricey) I wont be doing that.

Thanks for the healthy discussion on this topic. Nice that we can disagree without getting personal :rolleyes:

All the best,

Phillipj

:beer:

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You are correct I probably wont notice anything... But as much as I want to let the car alone I can't. I got a very good deal on the headers and it will be a fun project. I may have them polished just to create a nicer appearance.

To get the full effect of the headers I would have to do all the X 51 components (airbox, throttle body and manifolds.) Basically the Porsche "powerkit" without the cams and heads.

Unless those fall out of the sky (they are very pricey) I wont be doing that.

Thanks for the healthy discussion on this topic. Nice that we can disagree without getting personal :rolleyes:

All the best,

Phillipj

:beer:

Phillip:

I agree that you should probably have no problem removing the manifold bolts. When you install the new bolts, make sure to coat them liberally with anti-seize compound.

On a 13 year old car, it would be quite a different story, as that is what I am dealing with now: http://www.renntech.org/forums/index.php?s...c=30128&hl=

Still working on it. Making some progress.

Regards, Maurice.

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I agree that you should probably have no problem removing the manifold bolts. When you install the new bolts, make sure to coat them liberally with anti-seize compound.

On a 13 year old car, it would be quite a different story, as that is what I am dealing with now: http://www.renntech.org/forums/index.php?s...c=30128&hl=

Still working on it. Making some progress.

Regards, Maurice.

Thanks Maurice,

I wouldn't have done that unless you mentioned it.

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For the sake of discussion...

2) People keep saying that the S headers are restrictive because the three tubes go through the same restrictive point. This would be a problem if all three cylinders were evacuating gases AT THE SAME TIME, but imagine the flow through this header with each cylinder exhausting gases in SEQUENCE. Under those conditions you might actually set up a continuous high velocity flow (taking advantage of the restriction to impart a venturi effect) that would help to suck the gases from each cylinder.

I guess this is true if the engine RPM is low (low exhaust gas flow). Depending on how fast the exhaust gas excavated from that junction, in higher RPM, this "venturi" effect may create a problem (bottle neck).

I would guess the X51 header is designed to improve the top end performance. The low end performance may be compromised.

Thanks,

Sinclair

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You have a valid point.

I will be adding the headers this weekend. I will post the results after I drive the car. I don't mind being proven wrong. We will see. At least my experiment will give others good feedback.

Thanks for all of your input.

:renntech:

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