Heat exchangers

[Bazgillie]

ejgs
The best tool for this job is a Dremmel with a long thin burr to cut through the nuts and bolts, with the speed control it is much more contollable than a grinder and will get into more places. If you are careful you can cut down the side of nuts and split them to remove them.
Baz

 

[Guest]

Well last year I replaced only the heat exchanges with a Stainless with mild steal connectors. Bad move. This year have had to replace the exchanges again due to corrosion!! Not impressed with the mixed ones. So make sure when you do it ensure that they are fully stainless. In the end I went for the straight through system from Design 911 (actually through Euro Parts). Sounds Great and more power.

As I don't have space had to get the mechanic to do the work. Just as well as many of the bolts needed heating and the Exhaust Air Injector system needed to be removed (now in the attic). Also just found out the clutch arm does just touch the exchanger so may need to adjust it slightly?

What's in the kit:
Powerful straight though system all Stainless steel parts, offering more bhp and a fuller sound. for 911 1974-83 2.7L / 3.0L Made in Denmark
kit Includes..

1 x single big bore outlet rear silencer
2 x heat exchangers,
2 x oil pipes
8 x gaskets.
2 x silencer straps.

Good Luck

 

[nathan 1981 930 G50]

ORIGINAL: John Phoenix

The most important thing (which has been said by tripe) is you will need a special tool for the socket headed nuts holding the heat exchangers to the heads. I bought mine from www.design911.co.uk it cost about £25.00 from memory but worth every penny. It is very rigid and certainly I could not have undone these socket headed nuts on my car without it.

I just sawed off an allen key in a vice (to make it straight only) & then put it in a socket. Worked fine. Cost, a set of 'Chrome Vanadium' Allen keys. Don't buy ones that dont say they are 'CrV' as they might just bend.

Oh, and a nut splitter was very useful
http://www.screwfix.com/app/sfd/sea/searchresults.jsp?howMany=10&searchText=nut+splitter>se=goog>kw=nut+splitter#

These were also useful
http://www.screwfix.com/app/sfd/cat/pro.jsp?cId=102089&ts=38732&id=96028

 

[2.4te]

Suggest you fit a set of 'early 911'-style SSI heat exchangers + exhaust. They are the ultimate, will last the life of the car and release a few more horses at the same time.

 

[Strictly]

Hiya bud thanks for reply, so i should go for early 911 s/s exhangers and exhaust; a few extra horses sounds nice! What would this be 72-77 2.7 type or earlier?

 

[nick3814]

As I understand them Luke SSI's are SSI's if you know what I mean all the same fitting all the years leading upto the 911SC, the stud pattern on a 3.2 is different as I know from experience trying to fit 3.2 exchangers to mine a couple of years ago!!

SSI's aren't cheap mind, not to mention you need a new rear silencer and oil lines to negotiate the different shape of the SSI's to normal exchangers, no change out of £1200 ish!!! Theres some chat on this link about them which may interest you;

http://www.porscheclubgbforum.com/tm.asp?m=316301

Nice if you can budget for them though.

Mine had to be done when I first got her and I fitted galvanised heat exchangers and now have a stainless pre silencer bypass pipe and a stainless rear sports silencer although I use the word silencer in the loosest meaning of the word, she sounds absoloutley mint [] and I don't believe there will be any difference in the power gains between mine and a set of SSI's although some may say otherwise!

Enjoy.

 

[bones]

You need no later than 74, if you look at the pics of my car you will see the system I have which is a set of used (vgc) mild steel 73 HEs with a Triad exhaust. To release power from the SC engine you need a genuine twin header system. The original system with a crossover pipe just robs the engine of power - fact - stainless is longer lasting but is only needed if you use your car continually in wet weather. Whole sytem including oil pipes cost about £600.00 back in 2002. A lot of aftermarket 'sports' mufflers just make more noise with no substantiation of power increase. If you look at the Triad site there is a dyno test on there.
http://www.triadwestperformance.com/images/CRANEY_TXT.htm

 

[2.4te]

Bones- As I recall, condensation forms in the exhaust as a byproduct of combustion? It will rot mild steel heat exch from the inside, but not stainless steel ones.

 

[Strictly]

Thank you, great advice once again! [] []

I wont buy the pair of 3.2 heat exchangers as they wont fit, due to the bolt pattern being different.

here is the ebay link if someone needs them....

http://cgi.ebay.co.uk/ws/eBayISAPI....m=170181830824&ssPageName=STRK:MEWA:IT&ih=007

Ok at £1200 i cant budget for the s/s exchangers and exhaust, so will go for the early (pre 74) style. I will do a bit more research on this, using the links, so i know about the oil pipes, etc.

I am going to pull the engine/gearbox in a few weeks and change the clutch, so what i'm trying to do is get everything else, like heat exchangers/exhaust stockpiled and i can do it all at the same time...

thanks for the info - really appreciated.

Luke

 

[bones]

That's true SS is best but not everyone can afford the outlay for SS. If the car is run fairly regularly you should get a good long life from mild steel, mine are currently 7/8 years old and look perfect. I forgot to mention that my 'used '73 HEs' are infact pattern parts so not actually original items. hence 7/8 years old not 35!

 

[bones]

Try breakers for used pattern parts, Pro9 supplied my used HEs and are very good for finding older parts generally. My HEs were £180.00/pair.

 

[2.4te]

Luke,

Visit here:

http://www.ddk-online.com/

where there are occasional group buys for the SSIs, but regardless, the guys on DDK will know the best place to buy at the best price.

 

[Strictly]

Thanks for the help so far - what do reckon is the likelyhood of breaking an exhaust stud when removing the heat exchangers?

I know thats a difficult question to answer, but from reading the 101 projects book, it sounds like if you break a stud, its engine out for drilling. Im could settle for that as got to do the clutch as some stage, but in the book it talks about having to rebuild the bottom end because of swarf from the drilling (unless he was talking about a head stud).

Any comments? If you think that a few days of plus gas soaking, followed by heating the nuts up (what about using a nut splitter?), is normally fine then i'm going to go for it, if it tends to be a bit hit and miss, then i think i might forget about it!

Luke

P.S.

I have just pulled the rear calipers off (to sort the handbrake). My god the access to the rear caliper bolts, and hydraulic brake line (at the caliper), was surprisingly tight! I though beetles were not for the fainthearted, but porsche, well....better get used to it! I can understand the joke now about needing an octopus to change the spark plugs at the factory!

 

[bones]

lots of your favourite penetrating oil , if that fails try heating nuts cherry red and then freezing them with compressed air from a can, after that nut splitter or chisel or better a dremel if you can get in there, sometimes they just won't budge and that's when you end shearing em off.

 

[2.4te]

I just removed mine last June. Got myself worked up about the difficulties after reading all I could in books and internet. Enlisted the help of a friend who's a professional engineer, for moral support. At his recommendation I bought new socket and allen wrench from Snap-0n, to avoid the very real possibility of rounding the corners off with worn tools. It took a while for the tools to arrive (2 weeks) so I soaked the nuts in Plus Gas every night religiously over that time. On D-day, my friend brought round his his oxyacetylene torch to heat the nuts, but suggested we have a go first to see how tight they were. They loosened immediately- no heat! A lot of fuss about nothing in my case, though we were careful. I was lucky. You could be lucky too.

I note that there appears to be an imminent group buy of SSI's on DDK.

 

[nathan 1981 930 G50]

Use a nut splitter, I broke my first stud and then thought about using a splitter, got them all off perfectly, ran a die over the studs to clean them up afterwards. Wish I had thought of it first...

 

[Strictly]

Thanks boys, youve really given me the confidence i needed to tackle the job! Im going to look into which exhaust system to get, and then go for it!

I was dreading it, but youve really boosted my confidence on this particual job! Nut splitter and Plus gas - great tips! Thank you!

 

[Bazgillie]

Get a Dremmel and a bur type cutter and you can cut through each nut and split them off, then clean up the threads with a die nut, saves a lot of pain. Baz

 

[Porker993]

Here's to Dremels - b...dy brilliant for cutting through metal, nuts etc... Got me out of some tight spots with the Landy.