Fitting 993 Heat Exchangers to 3.2 Carrera

[sladey]

This has been written up before by RB - thought I'd share my experience of doing the same thing.

 

I normally have to get all my work done at week-ends which can be a bit stressful when you have to get the car ready for Monday morning. At Christmas however I tend to save up bigger projects and stretch them over the whole week, taking the car off the road - I only work on it for 3 or 4 hours in the morning and can do family stuff in the afternoons - win/win

 

This Christmas, as the title suggests I was installing 993 Heat exchangers. I bought these off Richard Bernau, along with a custom M&K backbox he'd had made. The flanges had already been flipped so that save me a job, and reducers had been welded onto the heat exchanger holes which would make it easier for me to fit the pipes. Having the heat is vital for me as I'm driving it every day.

 

This is what my car looked like before I started - M&K backbox, but as I've backdated the car it doesn' sit well (you wouldn't notice that on a 'normal' 3.2)

 

 

Here's a pic of one of the H/E's showing the reducer bit welded on

 

 

Before I started the work I noticed that in one of the H/E's (the one where the flanges had been flipped) there was a thick groove down inside the exhaust tube, from where the pipe had been cut. I bought some of this exhaust filling paste and rubbed that into the gap - grinding it all relatively smooth afterwards

 

 

 

I'd read a lot about the job before starting and did the following in preparation:-

1. Ordered early style oil pipes - ordered these from Tripe. They just route the oil under the front of the engine to the thermostat instead of round the back (where they would foul the H/E's).

2. Ordered some 12mm M8 nuts - I'd heard that access to some of the buts was a nightmare and the smaller nut size helps

3. Ordered necessary gaskets, and 4m of heater pipe, and a bunch of stainless jubillee clips for fixing it

4. Booked the car into my local garage to get them to crack off the nuts with the car on the lift - I'd read so much about this being a nightmare job, and for m the aim was that I would enjoy doing the work, so having them crack them off and grease them up seemed a good move (it was)

 

Step 1 - remove old system

 

Pipsy. All the buts came off easily except for one - the last one - where I had to do some BFH surgery to the old H/E to allow me to get a socket onto it properly.

 

 

 

Once off it was easy to see why one of the manifold pipes had been blowing a little - one of the flanges had come off altogether

 

 

Step 2 - change oil pipes

I'd read up on this too - you have to undo the nut on the side of the engine and also the nut at the other end on the thermostat. The one on the engine wasn't a problem - access is easy. The one on the stat was a different matter though. You can't get to it properly (I suppose if you had to you could remove the outermost nut first to allow you access). Dremel was my friend - I cut 2 deep grooves in the nut and then a big screwdriver and a couple of whacks with a BFH and off it came.

 

The two pipes you order fit together - in hte pic below the all metal one connects to the engine, and the banana bit runs under the engine.

 

Fitting the new pipe onto the stat isn't easy - it's a 36mm nut - so following advice elsewhere on this board I ordered a new spanner and chopped it up.

 

 

 

The chopped version works really well (I'd be happy to lend it out to other people doing this job)

 

Step 3 - Fitting the heat exchangers

 

Before I started I measured the internal diameter of the head, the old H/E's, and the new ones. And the gaskets.

Head - 40mm

The old H/E's had a sleeve that goes into the head, choking it down some more - to about 36 IIRC

My new 993 H/Es had internal diameter of 38/39mm

The existing (old) gaskets had internal diameter of around 40mm

The new gaskets had internal diameter of around 36mm (IIRC - the pics haven't come out well)

 

I decided to re-use the old gaskets - they looked in an OK condition, and the size was just right.

 

Fitting the boggers....

 

The left hand side bank went on without any real problems. It's all a bit fiddly and you need to use washers with those allen keys nuts to make sure you're not having to wind them on too far.

 

The right hand bank is also OK for 5 or the 6 nuts. When I got to that stage I knew the last one was going to be a swine, so I left it for the next day.

 

It took me over two hours to do that nut up.

I bought this tool from Halfords specifically for the job

 

 

It was the right tool, but you still have to grind the shoulders down a bit to let it turn properly

 

The problem for me was getting the nut started on the thread in the first place. Again you want washers on there partly because if you have to wind the nut all the way in you won't be able to get at it once it's gone beyond a certain stage.

 

Once I'd sussed how to do it it wasn't actually too bad.

Step 1 - coat some washers with copper-ease, and using very long-nose pliers I pushed them onto the stud. The stuck there at an angle so they didn't fall off

Step 2 - I found I could get long-nose pliers in from one side, and get a screwdriver in from the other side. I then bent the end of the longnose pliers with some heat. I then fed the nut in from one side, and when it was sitting under the stud I used the screwdriver to hold it in place. I then closed the pliers up and used them to push on the flats of the but to turn it, until I could see that the thread had started. I was holding it like this.

 

 

Once the thread had started I switched to the Halford tool and was able to screw it in tight.

 

Getting tired writing this now so I'll finish off tomorrow

Edited January 3, 2010 by sladey

[scottbombedout]

What a fantastic write up. Looking forward to the next bit

[sladey]

OK back again.

 

Just to add to that awkward nut part - here is a pic taken from the side - the bit of stud you can see coming down is what you have to get the nut onto

-not easy

 

At this stage it looked like this:-

 

 

There is a very slight dip on one side - it's about 10mm higher than the other - not complaining - I knew about that beforehand and it's way better than my old system.

 

The next stage was to 'offer up' the rear bumper. With it jammed roughly in place I marked out a line round the tailpipes using my finger as a spacer. It was also fouling the right hand side of the backbox so I marked that up as well

 

then took it off and cut around the marking

 

 

I used me new air-powered die-grinder to cut the last bit of the holes.

 

With the bumper now fitted it was starting to take shape:-

 

I've never actually liked the 3-pipe arrangement as I've always thought the 'spare' pipe spoils the look. When I bought it was hoping I culd paint it black and it would be hidden behind the bumper. You can see from the pic above that this is not how it's panned out.

 

Solution? Grinder

 

 

 

 

Unfortunately I haven't taken a pic showing that area - here's one from the other side

 

Basically now the end's been cut off I'm really pleased with how it looks. I'd had to butcher the left hand side of the bumper for the previous back box, and that bit still doesn't look wonderful but the third pipe now looks very unobtrusive. I'm planning to repair the butchered fibreglass in the coming weeks as well

 

Last stage - add heat

It was very important to me that I have heat. This is not really so hard to do, but does require that you backdate the heat.

 

I'd already backdated the heat in mine - but as it's an 87 3.2 it only had a left-hand heat outlet from the main fan, which is fine, but it meant I'd have to do the right hand side one as well

 

NOTE:- as I knew I'd be taking off the engine tinware I left the bumper off at this stage and didn't fit it until I'd finished with the heat tubes

 

There are 3 parts you need for the right hand side - I ordered these from Tripe - here's a pic

 

It's a bit like a jigsaw puzzle - you've got the bracket in two parts and then the plastic tubing.

 

Once you remove the right ahnd blanking plate from the rear of the engine you're left with this:-

 

Here's me trying to fit it in place

 

What I (eventually!) discovered was that with the piece fully assembled it's impossible to get it into place - the trick is to part-disassemble it (do up the two bolts just into their threads) and once you've got it in place then assemble it. Of course that then is a bit of a ball-ache - but it's not impossible.

 

For anyone that's not sure how the heating works it couldn't be simpler - air is blown from the big fan at the rear of the engine through the heat exchangers where the hot exhaust pipes heat it up - it then passes from them into the flapper boxes and then on into the car

 

For the conversion to 993 heat it just means you need four pipes in total:-

A pipe from each side of the engine to the side/top of the relevant heater exchanger.

Then a second pipe each side from the front of the heat exchanger up to the flapper boxes

 

Here's a pic of the left hand side of the engine after the tubes had been fitted

The tube on the right is the one that's come down from the engine fan; the one on the left is the one going from the inside front o the heat exchagers up to the flapper boxes.

 

I ordered my pipes/tubing from Merlin motorsport (Linky linkersson ) - I got the 76mm tubing and ordered 4m of it just to be sure. I actually ended up with just under a metre left over.

 

Although I ordered all 76mm diameter, I could have used a smaller diameter tubing for the connections from the front of the H/E's - not sure what size would be a perfect fit - I suspect that using the size of tubing I had means that the reducers welded onto the front of my H/E's were redundant as my tube would have fitted onto the original hole.

 

I also ordered 2 70-90mm jubilee clips, and another 4 smaller ones (I think 50-70mm)

 

The two pipes coming off the fan are a fair bit smaller but it's no big deal - just snip some of the copper wire out of the inside of your flexi-tubing , and then wrap it round, fixing with the jubilee clips.

 

The only gotcha is that the right hand tubing has to pass through the engine tin to get to the underside of the engine (where the heat exchangers live - remember?) This again was surprisingly easy

 

The tinware can be removed by taking out a few bolts. I took out the side tinware and put it on the bench

 

I then cut away about 4 inches, and folded it back- beating it flat (just so there were no sharp edges to cut the tubing), then refitted the tin. There will wasn't quite enough room so I took out the rear piece of tinware, and cut a bit off the right hand corner. This left a hole plenty big enough to squeeze the tubing through

 

Connecting the tubing up was easy - just doing up the jubilee clips

 

Then fitted the bumper and Roberts your Mother's brother.

 

Hope this helps anyone thinking of doing this in the future

 

Will post driving impressions separately

[sladey]

Driving impressions:-

 

Firstly I'm absolutely knocked out by the look of the setup - the rear of my car has bugged me for a while and this really tidies it up beautifully. I've got a few more plans for the rear of the car but will share those when I've done them

 

I was told that the exhaust would be LOUD and also sound great. It ticks both boxes.

 

When I first drove it to work this morning for the first mile (in slow moving traffic) I wasn't really happy with it - felt it was too drony. BY the time I got to work though I'd changed my mind and was starting to reallt like it - I don't know how much of that is the muffler/connections 'bedding in' (if it can do that in 10 miles!) and how much was me getting used to it

 

Had a listen to it from outside the car tonight and it doesn't actually sound much louder than it was before (bearing in mind I had a HUGE exhaust leak before). It is louder and more Bassy from inside the car though so I reckon I'm getting resonance from the backbox transmitted through where it's strapped to the rear of the engine. I'm going to put some insulation there to try and tone this down.

 

I'm loving the sound of it

 

With regard to driving it's difficult to tell at the moment - roads are pretty icy and slippy round here. However it feels like I've lost a little bit of mid-range torque, but it seems to have bigger lungs - happier at higher revs (as am I!). I'd thought previously that losing torque would be a bad thing but it's not - I'm revving it a little bit more and the whole thing feels exciting.

 

Cheers

 

Mark

[MarkJ]

Fantastic article Sladey the twin rear pipes look superb and suit your vintage rear

 

Quite bizzare reading this first thing as i had a dream last night in deep sleep where i met a couple of you clever IB'ers and they were doing all sorts of fettling on my car for me in a nifty well equipped garage, whilst we were chatting ! Obviously reading too many of these great articles

[jevvy]

Good work Sladey - hows ya knuckles looking?

 

I'd try running without muffler straps for a bit, the rear box is so light compared to a standard system that I'm not entirely sure the straps are needed - mine has been strap free since fitting the 3.6(40k kms) and I've had no problems.

 

Oh yeah what about a re-map to try to win a few mid range ponies back?

[Jammo]

Top Job Mark and cracking thread.

Youtube soundtrack ready yet????

Regards

 

Jammo.

[strosek34]

Great write up Sladey,

 

Can't see any piccies at work but I'm sure it looks good as well.

[Northy]

+1 on strapless M&K. No ill effects so far.

 

Great job Mark, it's quite satisfying when it all works isn't it?

[sladey]

Thanks for the comments.

 

I'd thought about strapless - my only concern is that as it's quite low I scrape the back (well I did in the old one) going in and out of my drive.

 

I'll try it with the insulation and also strapless - if it's better strapless then I'll just have to alter the pavement outside out house

 

I'm happy to do a youtube clip but need to wait until this snow has gone

 

Cheers

 

Mark

[Richard Bernau]

Great job Mark - really pleased this has worked for you. Pretty much all your experiences mirror mine including your driving impressions. I can't see pics at work but may also sugest you cap the third outlet and make it work thru just the 2 rear outlets. Seemed to sound a little better to me.

 

Andy P was advising me to somehow insulate the muffler from the mount which may be an alternative to the strapless suggestions so far. A piece of bike inner tube between the mount and the strap may be enough.

 

One other thought, if you need quiet, then cap the 2 rear pipes and put an insert in the 3rd. For general driving, this made a huge difference and takes away 90% of the resonance. I also got used to wearing my ipod with ear buds for long trips and that made the full noise set up fine even with zero sound deadening in my car.

 

RB

[MarkJ]

if you dont strap your rear muffler, dont you run the risk of resonance damage to your head studs and welds in the pipe system? That cantilevered rear box will be constantly vibrating and allowed to move up and down, if not strapped, and that resonance/vibration will transmit back down the exhaust components. Perhaps it wouldnt be enough to cause any problems, but from an engineering view i wouldnt be happy with it un-strapped.

I can speak from experience on this as i worked on the B of the Bang in Manchester (was one of the tallest sculptures in UK). If any of you are aware, wind whistling around the spikes caused low level resonance that transmitted down the length of the spikes (like a ripple effect) and caused the welds to vibrate themselves apart and failed...and a steel spike fell off ! Fortunately not on anybody

[Richard Bernau]

if you dont strap your rear muffler, dont you run the risk of resonance damage to your head studs and welds in the pipe system? That cantilevered rear box will be constantly vibrating and allowed to move up and down, if not strapped, and that resonance/vibration will transmit back down the exhaust components. Perhaps it wouldnt be enough to cause any problems, but from an engineering view i wouldnt be happy with it un-strapped.

I can speak from experience on this as i worked on the B of the Bang in Manchester (was one of the tallest sculptures in UK). If any of you are aware, wind whistling around the spikes caused low level resonance that transmitted down the length of the spikes (like a ripple effect) and caused the welds to vibrate themselves apart and failed...and a steel spike fell off ! Fortunately not on anybody

 

Fully agree - its sound advice, not just $0.02 worth. I think isolating the strap from the mount is the better plan.

[MarkJ]

I think isolating the strap from the mount is the better plan.

 

Yes, i have a piece of exhaust rubber between mine, as thought of by the quick thinking mechanic who fitted it.

[sladey]

Thanks for the comments.

 

I'm actually loving the sound more and more each day - the resonance is either subsiding a bit or I'm going deaf.

 

I checked the car against the pavement at home the other day and it's too close for me to leave it unstrapped - leaving aside resonance issues there's every chance I'll be scraping it every so often, so I'm definitely going to insulate the strapping. I've got a couple of people posting me some exhaust wrap and I was planning on using that - I'm going to be heating and bending the mounts as well because they don't sit square with the muffler at the moment.

 

I'd thought about bike inner tube but I was concerned that the heat from the muffler would melt the rubber. When the bits of wrapping come through I'll give it a go - looking forward to it. If it just taks a tiny edge off the internal resonance then it'll be perfect

 

I went for my weekly exercise class today - the trainer can normally hear me as the car enters the village, but this time she said she didn't hear it until it was outside the hall - I think that's probably due to the sound dropping an octave or two.

 

When I've done the mounts I'll try uncapped, and with the baffle in the single pipe etc. Looking forward to experimenting because I'm very happy with it as it stands

[Richard Bernau]

I'm going to be heating and bending the mounts as well because they don't sit square with the muffler at the moment.

 

I'd thought about bike inner tube but I was concerned that the heat from the muffler would melt the rubber.

 

Good reminder, I bent the mount ot make it fit. Lazy, but I just stood on it and pulled the ends up - worked a treat and made me feel really buff - LOL

 

Not sure heat would be that bad but if you have wrap to play with then even better.

[Tripe]

I used the the mount for a 993 catalytic converter as the support for the modded 930 muffler on the SC, works well.

[jevvy]

I recon with standard 3.2 HE's, crossover pipe and cat at the side the exhaust bolts are holding the same if not more weight/vibration than you get with rear exit 993 HE's, M&K and no straps. There is a small brace on 1 HE to gear box at the front but other than that the additional pipework on a standard setup is unsupported other than the exhaust bolts into the head.

 

993 HE exits also seem to be a bit closer to the heads, my setup hardly shakes about at all.

[sladey]

You come and fill in my pavement Jev and I'm happy to run strapless

[MarkJ]

any chance of a vid of your new sounds Sladey?

 

I am much happier with my TT setup over stock but its still not quite doing it for me in the audio department. Thats no detriment to the TT system, i just think that as the outlet is on the pax side, i just dont get the benefit of it from the pilots position like i am used too. Its a personal thing but i want to hear the fruits of my right foot doing the work. The flip side is others on the outside tell me the car sounds great/loud..but what counts is what i experience, not in it for the pose factor.

[jevvy]

Was kind-a answering the vibration/weight debate rather than your grand canyon garage entrance issues

 

You need some go-go gadget suspension mate.

 

[REX]

Top work Mark, I reckon I lost midrange to but it felt better topend. Unbolt the STD silencer bracket, strap it to the box and measure the distance between it and the block and I'll do you some ally spacers and longer bolts, engraved on every face.

 

What I did on mine.

[sladey]

Thanks Jev - I was just being smartarsy as usual - I do quite fancy go go gadget suspension though

 

Rex - thanks for the offer (especially the engraving part!) but I've been working it this morning and sorted it out - combination of heat, bending and panel beating the bracket got it so that it fits nicely - also it wasn't just the wrong distance - the ends were at the wrong angle as well, so a spacer wouldn't have fixed it - all sorted now, along with the insulation. Took it for a short drive this morning and very happy that it's taken the edge off the resonance.

 

Also been busy this morning. Since I fitted the backdated heat to the right hand side of the engine I haven't been impressed (this week) with the amount of heat coming through. Admittedly it's been a very cold week but on the previous system the heat was pretty good really.

 

I've been thinking on this all week and reckoned it is down to the small hole available to collect the air from the engine - it's practically a slot - here's a pic:-

 

So I thought I'd have a go at taht this morning as well - took it out to have a good look at it. You can see that there are plastic knobs sticking into the slot from each side - presumably to hold it apart.

 

Firstly I cut through the middle of that.

 

Then I got some aluminium tubing I'd got lying around and cut a bit and a half off it

 

Then I squeezed the slot from the ends to widen it, allowing me to slip the alu tube in there, over the two knobs that were still there - the result is this:-

 

And here's me about to fit it

 

Dramatically increases the throat of the air intake. I don't reckon it will have any noticeable effect on the engine cooling either as it's still miles away from the air passing over the barrels. On my short drive this morning I started to feel the heat coming through - will be able to tell better on the drive to work on Monday.

 

any chance of a vid of your new sounds Sladey?

 

I am much happier with my TT setup over stock but its still not quite doing it for me in the audio department. Thats no detriment to the TT system, i just think that as the outlet is on the pax side, i just dont get the benefit of it from the pilots position like i am used too. Its a personal thing but i want to hear the fruits of my right foot doing the work. The flip side is others on the outside tell me the car sounds great/loud..but what counts is what i experience, not in it for the pose factor.

 

Will do some sound stuff when I get a chance - need to wait for this snow to go first

Edited January 9, 2010 by sladey

[sladey]

Took the rear caps off this morning for the drive to and from work. My ears aren't bleeding any more, which is nice.

 

At tickover and up to 2K revs it's a real throaty burble which you can live with.

 

From 2500 to 3000 revs it's like your head is about to explode - it hurts like when you dive too deep in the swimming pool.

 

Then at 3K revs it breaks clear and you have the most glorious sound ever as it shoots up towards the rev limiter. It seems to have even more 'go' and it bellows like a wild animal - fantastic.

 

As it stands, it's one to save for trips out - not for every day driving.

 

Doing a 3 point turn in tescos car park without any revving, I set off a car alarm.

 

RB - did you notice any reduction in resonance when you uncapped the two but capped the side one (as opposed to just having all three uncapped)?

 

Have re-capped it tonight

[Richard Bernau]

RB - did you notice any reduction in resonance when you uncapped the two but capped the side one (as opposed to just having all three uncapped)?

 

Yes, indeed - a little. My resonance was 2200-2800rpm and I mainly had to drive around it. For pottering around, I could mainly drive from idle to 2200rpm and once on the move, I tried to keep over 2800rpm.