924Board.org

Kenodog · Joined: 25 Jun 2003 Posts: 2669 Location: Vancouver,B.C.

So i'm well on my way to mocking up an exhaust collector for my 931.

I have already started on the g-line program for the waterjet machine to cut the three main flanges out of 304 ss and last week I got a piece of 1 1/4" steel plate to make the welding/stress relieving fixture.(It takes inconel 2 hours @ 1000F to stress relieve after welding.Ouch.)
I guess the reason for this post is to see if there is any interest from you 931 guys in buying one ? They would be made in a log style out of formed .105" or .125" thick Inconel 625 plate with 304 or 316 ss flanges.These would be a direct bolt-on replacement for ours.There could be an option of welding on a different turbo flange but for now like I said it'd be a direct 3-bolt replacement.I'm personally going to have mine ceramic coated,inside and out,for the additional $100 I think it's worth it.
Of course i'll have pics of a finished unit up here before I ask anyone to commit,right now i'm just seeing if there's interest from you guys.I'll be building at least one anyways for myself.

As far as cost goes I think when all is said and done they would be about $400-$500 per unit.With what the materials cost at that price i'll be lucky to make $50 on these but that's not why i'm doing it.For me this is a "Pay it forward" kind of thing,good car god karma.However,for that price you'll be getting an exhaust manifold that will last FAR longer than your 931,no cracks,guaranteed.As an added bonus it'll only weigh about 1/4 of our cast iron lumps.
(Maybe about 20% cheaper if you'd like 321 ss instead of Inconel but there wouldn't be a guarantee on the 321 unit.)

So there it is,please feel free to add comments or ask questions and i'll try my best to answer.

Leigh.
_________________
1979 Euro 931, Olive
1981 931, Sabine
1991 Ford Ranger XLT 4x4, Ricky
1996 Ford E-350 ex-FedEx Van
2014 Mazda CX-5 (Kinderwagon)
2019 KTM 790 Adventure
2024 KLX300
2024 KLX140

Paul · Posted: Mon Feb 06, 2006 8:01 am Post subject:

Are there any (expensive) issues of sending them from Canada to the US?
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

flosho · Posted: Mon Feb 06, 2006 8:18 am Post subject:

come spring time, I may be interested.. are these going to be made to order or more of a group buy type thing?
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[This Space For Rent]

Kenodog · Joined: 25 Jun 2003 Posts: 2669 Location: Vancouver,B.C.

Paul ,I can ship from the US if you'd like.

Flosho ,they would be made to order.Once I make the first one and get the set up right they shouldn't take more than a couple of weeks to deliver.
_________________
1979 Euro 931, Olive
1981 931, Sabine
1991 Ford Ranger XLT 4x4, Ricky
1996 Ford E-350 ex-FedEx Van
2014 Mazda CX-5 (Kinderwagon)
2019 KTM 790 Adventure
2024 KLX300
2024 KLX140

flosho · Posted: Mon Feb 06, 2006 11:03 am Post subject:

sequential · Joined: 18 Nov 2005 Posts: 500 Location: BANNED

Keno ,
Great idea , plan execution etc. but why a log? Seems like a lot of work for a log type manifold. I really like your approach as you have given the process a lot of thought, make the xtra effort and do a jig for a tubular type manifold
_________________
928 gts prototype
baby blue engine block
steam in 1,2,3,4 sometimes
cold star issues while on stands
112 whp with new 4 valve head and MIS 2

Kenodog · Joined: 25 Jun 2003 Posts: 2669 Location: Vancouver,B.C.

Sequential,i'm going log style for a few reasons;
Cost- 1 pce of $180 plate will make the entire body for the manifold whereas about 2 feet of tubing would be needed @ $170 per foot.
Strength- The plate i'm reffering to is .125" thick while the tubing is only .062",in the long run this is going to mean way more strength at high temperatures.Twice the strength for half the price ? no brainer.
Making the fixture- It will be WAY simpler to make a jig to weld flat pieces as opposed to one for a tubular contortionist,also the total lack of space down there is a drawback.
Reality- Most guys are just going to want the cheapest bolt on replacement not some super duper racing component.The new manifold will work as well as,and probably better,than the original.It will last longer and will come with the option (later) to have a 4 bolt turbo flange if that's the route THEY want to go.Not all of us want a 400 hp 924.And if they do then THEY can do the leg work,i'm just doing it for fun.
_________________
1979 Euro 931, Olive
1981 931, Sabine
1991 Ford Ranger XLT 4x4, Ricky
1996 Ford E-350 ex-FedEx Van
2014 Mazda CX-5 (Kinderwagon)
2019 KTM 790 Adventure
2024 KLX300
2024 KLX140

-nick · Joined: 16 Nov 2002 Posts: 2699 Location: Cambridge, MA

Kenodog,
I think it's a great idea, non-cracked stock manifolds aren't going to become any more plentiful anytime soon.

I'll preface with- I'm not in the market (if you had caught me last year when I was looking for a replacement for my cracked manifold, I would probably have jumped on it), just curious about your design. The stock'er has a second chamber that runs from where the turbo flange sits, under the manifold, back to the wastegate opening to feed the wastegate. To keep a constant pressure across the ports when the wastegate opens, I presume (a guess). Are you going to incorporate this? Or have you looked into if it's truly even necessary?

ps- having a four bolt flange option could get you more bites, that's what i'd go for. I can only imagine what a modern turbo would do to transform these engines.

best of luck
nick

macBdog · Posted: Tue Feb 07, 2006 7:33 am Post subject:

I would jump at the four bolt flange version. Three bolt turbos are harder to find.
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1979 931 with a 350 chev
1973 911E with EFI

Mikri184 · Joined: 12 Sep 2003 Posts: 746 Location: Ferndale, WA

Happy to see you decided not to part out your car, it would of been a shame, and glad to know you still find interest in improving it, WAY TO GO, KENO
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MunkPuppy · Posted: Tue Feb 07, 2006 11:55 am Post subject:

I will be interested in the springtime as well, Keno.
_________________
'80 931 FOR SALE

"It's a shame that stupidity isn't painful"
-Anton Szandor LaVey

Kenodog · Joined: 25 Jun 2003 Posts: 2669 Location: Vancouver,B.C.

I was actually thinking of possibly moving the wastegate flange to the front of the manifold so there isn't such a violent change in gas flow direction when it opens.I've seen it done in "Maximum Boost" and it seems to make way more sense to me.However,having said that i'd also like to keep things down there as stock and simple as possible and having to make a new "J" pipe doesn't turn me on so who knows.
_________________
1979 Euro 931, Olive
1981 931, Sabine
1991 Ford Ranger XLT 4x4, Ricky
1996 Ford E-350 ex-FedEx Van
2014 Mazda CX-5 (Kinderwagon)
2019 KTM 790 Adventure
2024 KLX300
2024 KLX140

jpab924 · Posted: Tue Feb 07, 2006 2:24 pm Post subject:

I strongly suggest not to use ceramic coating on the inside of a turbo`s exhaust manifold.

Paul · Posted: Wed Feb 08, 2006 10:50 am Post subject:

4 bolt with no allowance for a wastegate pipe might sell the best.
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

Kenodog · Joined: 25 Jun 2003 Posts: 2669 Location: Vancouver,B.C.

A 4-bolt with no wg would be easy schmeasy compared to what the original is.Thankfully Porsche put the head flange and turbo flange at a perfect 90 degrees.
The problem then is;what other turbo ? And how many guys would rather have that ? If so speak up and let me know.
Keep in mind though that a nice BB turbo is gonna run you about $750-$1000 depending on manufacturer and options.Then you have to plumb it too.With the cost of the manifold and new gaskets it'll end up @ $1500 !!

jpab924,I was thinking about that before but the guy that does it guarantees me that it won't come off.I may just do the first one on the outside and see how that holds up before I do an inside,we'll see.
I was thinking about tacking some small threaded bosses at a couple locations on the outside to screw a removable heat shield onto as well.Whatcha think ?
_________________
1979 Euro 931, Olive
1981 931, Sabine
1991 Ford Ranger XLT 4x4, Ricky
1996 Ford E-350 ex-FedEx Van
2014 Mazda CX-5 (Kinderwagon)
2019 KTM 790 Adventure
2024 KLX300
2024 KLX140