Heat exchangers

Bazgillie · Dec 16, 2004

Dear All
A project for over the winter that I am looking at doing is replacing the heat exchangers on my car as they are both well past their best before date. The question is which make and type to use stainless would be nice but at double the price is it worth it? What is the life expectancy of mild steel or galvanised or aluminiumised parts? There seems to be quite a range of prices for the same parts which supplier or maker would you recommend? Thanks Baz

Guest · Dec 17, 2004

Hi Baz,
I replaced my heat exchangers and exhaust last year. My wife had a weak moment and allowed me to get the SSI exchangers, to which we added a Dansk sports silencer. I have to add that I intend to keep the car for the long term and so this seemed like a sound (pun!) investment, if there is such a thing in car parts!! It is quite a long job to fit and requires a couple of new oil pipes, but the difference in sound, response etc is something else. Tie this in with the satisfaction of know that they are guaranteed for life and the price does not seem so bad. I had looked at some other stainless systems and concluded that with only a 5 year guarantee they were not much better than a decent steel system.
Hope this helps, happy to talk more if you wish.
Ian

bones · Dec 17, 2004

I recently fitted secondhand early heat exchangers from a breakers for £180.00 the pair. I had to cut off an extra mini cold start heat exchanger bead blast and HT paint them about £35.00 all in. I bought a Triad 2 in 2 out exhaust for £233.00 inc shipping and the oil pipes came from Bert gear for about £120.00. Stainless exhaust tips were £40.00 a pair from Porsch-Apart. I had no problems with broken head studs and the like and there is a noticeab;e performance gain. My car doesn't see rain very often so expensive stainless items are a waste of money to me. If you go for an early free flowing exhaust system instead of the restrictive nonesense fitted to the stock car and you want stainless buy SSI, Dansk are not worth the little money you save over SSI and contain mild steel components. If you are keeping the stock set up, it's potentially a mine field and the only way to get through it is to do plenty of research, call JZ, Autofarm and other independents for recommendations, ask what they fit, then ring around the suppliers and ask the brand name of what they are selling.
If you are keeping the car and you don't mind losing the stock set up I would go for an early style system and restore some power lost in the attempt to stop the SC outperforming the then flagship 928.

Bazgillie · Dec 19, 2004

Ian and Bones
Thanks for the comments and ideas. My car already had a stainless main silencer and I have fitted a stainless pre-silencer from Malton Specialist Cars which is a well made piece of kit at a good price. I have got a new stainless cross over pipe from E-bay another good deal. SSI exchangers would be very nice but time you change the oil pipes as well you are looking at a big bill. I will phone around suppliers and breakers and see what is available unless anyone has any other ideas.
Cheers Baz

bones · Dec 19, 2004

If you've already splashed out on the other stainless parts you might as well bite the bullet and finish the job off Baz. You might find some seconhand stainless steeel HEs in breakers as lot of SCs are being broken up for parts.

Guest · Dec 25, 2004

Baz,
Just a little more info on the SSI thing. If you fit SSIs there is no need for a crossover pipe or pre-silencer. I agree fully with you about the initial cost but as I am in this for the long run they seemed like a good buy. The longevity is clearly a big positive with SSIs, but the sound and extra (perceived or otherwise) is worth experiencing.
Good luck with the decision.
Ian

Bazgillie · Dec 30, 2004

Gents
Does anyone know if the heat exchangers from 3.2s and 964 are the same as SC ones as a breaker in Southamton has a set from a 1990 car.
Cheers Baz

engleflick · Jan 3, 2005

Hi Baz,

As far as I know the heat exchangers for 3.2 and 964 are different to the SC and cannot be used. In all the parts listings for exhaust systems they are always listed seperately. As ever I will wait to be corrected if I am wrong![

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bruceb · Jan 3, 2005

The later heat exchangers will not fit the SC as the exhaust diameters are different and I believe that 964 versions are a different shape as well. The carrera versions also have some sort of sleeve on the exhaust flange that fits the cylinder heads.

I also fitted SSI's to my car some years ago, it sounds great but quite a bit noisier even with a standard OE mild steel silencer as the stainless seems to give a sort of ringing sound to the exhaust.

If you are worried about noise I would stick with mild steel heat exchangers even with your stainless cross over and silencer. If I had to change my system again I would stick with mild steel.

good luck

Bruce

Guest · Jan 16, 2005

Well it looks like my baby needs the doctor (again) for the starter motor so I thought that I may take the opertunity to get a few outstanding areas sorted like the heat exchangers. I presume that these can be changed independantly of changing the exhaust. Is that correct or do I need to do the exaust at the same time? The exaust seams fine but the exchangers are knackered. As was well felt on Saturday's trip to the NEC for the Autosport show wearing thermals while driving.

Any suggestions on brand of heat exchangers?

Thanks and I hope to mak it to this months meet provided that my baby is on the road (that will make a welcome change!)

Cheers
Carrick

bones · Jan 16, 2005

You don't ned to change the exhaust , the rear box is a separate item. What make of HE you buy depends on whether you want to run to the expense of stainless or go for mild steel. If you don't use the car all year round mild steel will suffice IMHO. Unless you buy SSI and they require a different exhaust bear in mind that most if not all 'stainless steel' heat exchangers use mild steel flanges or other mild steel parts so they are not what they say they are! The name Dansk springs to mind but for real quality ask H&S for a price, expect that they will be expensive. For prices try Type 911, Bert Gear, even good used HEs will suffice if you can find them.

Bazgillie · Jan 17, 2005

Carrick
I have been looking for a pair of heat exchangers for a while and the best price I have found for new is £125 each for Dansk from Malton Specialist Cars who I have boughjt bits from before and found them to be very helpfull. Good second hand ones seem to be like rocking horse s**t. I have phoned and E-mailed a lot of the Porsche breakers most dont seem very interested in doing business or dont know the cars very well or want nearly as much as new so go very carefully. If anyone knows of anywhere that has got any please let me know.
Baz

bones · Jan 17, 2005

At £125.00 new I would say forget used and buy them , that's a fair price.

Guest · Jan 30, 2005

Baz

Thanks for that. In the end I replaced the left side only with SS Dansk (couldn't get galvanised and was recomended away from MS). Work done by No. 5 as the car was in getting a new starter motor. Thank god for roadside assistance eh?

Cheers

Bazgillie · Feb 20, 2005

Heat exchangers are done I managed to get a pretty good second hand pair from Discount 9 Auto £191 including Vat and delivery. What a pain of a job to fit though and I was doing it over a pit. Dont even think about it unless you can get right under the car.
What a terrible design they did not think about doing the job in years to come when the nuts have rusted away all of them on mine had rusted so much that a 12 mm socket would not grip them in the end I ground a split in them with the trusty Dremmel and then knocked the nuts of with a hammer and chisel. I cleaned the heat exchangers in an acid tank at work and sprayed them with cold galvanising paint. When refitting I changed all of the nuts for stainless and any studs that came out I replaced with 8mm allen bolts a long series allen key fits up the hole in the heat exchangers much better than a socket also the outer row of fixings where I have changed the studs for bolts can be done up with an allen key with the ball on the end which lets you get the required angle on the bolt. Baz

bones · Feb 20, 2005

Bet your glad that is over and done with Baz?
For anyone else considering taking off the HEs if your retaining nuts are not already rounded off badly and need cutting off consider these long reach sockets.
http://www.pelicanparts.com/catalog/shopcart/PORS/POR_PORS_PTOOLS_pg6.htm

tripe · Jul 14, 2006

If you intend to keep the car then I would recommend stainless. If it has been a while since the exchangers were last removed then the job could be quite involved. Your main problem will be corroded nuts and bolts. Personally I would remove the complete exhaust as it is quite likely that the bolts holding the heat exchangers to the cross over pipe and side silencer will need to be ground off.

To remove the lot you need to remove the six nuts holding each heat exchanger to the manifolds (special long allen key needed for three on each side), also undo the heater pipe connections at each end. Removing the steel bands holding the rear silencer to the bracket at the rear should allow the whole system to be removed (there may be a lambda sensor to undo on late 3.2 Carreras). Best lowered down using a trolley jack.

You can then seperate the components on the bench.

The side silencer and cross over pipe will probably need replacing, you may be ok with the rear box as these are often changed in isolation.

The main problem on removal is rusty fittings, be sure to soak the manifold nuts in plenty of penetrating oil well before attempting removal. The bolts often shear and if so replacing them could be the subject of another thread.

When refitting I would fit the new heat exchangers to the car first, then offer up the remaining components and loosely fit using new gaskets all round. Pattern exhausts rarely fit exactly and a bit of fettling may be required. Tighten up the bolts when happy with the fit.

All in all it should be a straightforward job, allow a day assuming you have no big problems.

bones · Jul 14, 2006

As you've posted in the SC section I'll assume we're talking about an SC. If you are replacing the whole system and you're not concerned about originality why not upgrade by fitting heat exchangers with equal length headers and a sports exhaust. There are a few options, use the search button. My recommendations are if you use the car only in fine weather then buy a TriadWestPerformance two in two out exhaust and pre 73 heat exchangers (all mild steel) with appropriate engine tin and oil pipe mods. If you use it in all weathers buy SSI heat exchangers in stainless steel and combine with a suitable 'sports' pipe in stainless too. Hayward and Scott and Dansk spring to mind. Look at my sig pics to see my SCs system, it unleashes quite a few ponies. My system all in cost about £600.00.

bruceb · Jul 14, 2006

The exhaust system replacement is a job that can be done by the home mechancic....as long as all goes well.

The main issue is corroded nuts and bolts and in particular the cylinder head to header nuts. These have a tendancy to shear off and then its the devils own job to remove the broken stud. Removal of the engine and stripping down to the cylinder head to replace the stud is the wost case, tres expensive!!!

Most porsche specialists will heat these studs up to red hot and then shift the nuts to minimise the potential for a broken stud. If your going to do this at home then a welding torch to heat the studs is whats required to do the job properly.

I had a similar dilema a few years ago when my exhaust failed. Any other car and I would do it myself, but like most things porsche there seems to be a right way and little else in between!

Guest · Jul 17, 2006

Hi ejgs,
I removed my exhaust system complete from my 1883 SC last year and serviced it replacing gaskets and bolts, I am pretty sure it had never been off before. I removed the whole system in one piece and used a grinder to remove the rusted nuts and then just pulled the system apart and punched out the cut off bolts. The grinder I used was a angle grinder you can buy from B&Q for about £12.00, the type you use to cut tiles.
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.
Have a look at there web site , you can buy all the parts you need and the 3D drawings show all parts.
I bought a presilencer in mild steel from design 911 which is made by Dansk.
Look at the Dansk product range on the web, the quality of my presilencer is very good.
I would recommend you have a go at this project ,the hardest part is removing the system once you have done this it is plain sailing.
cheers
John