Stainless Steel Exhausts

[engleflick]

I have got to replace the heat exchangers on my 1980 911 SC, as they are rather rotton. So I thought I will replace them (and the rest of the exhaust) with a stainless steel version, but on looking around for the best type I am now totally confused as to what to do for the best.

Some companies list 'sports' exhausts with large power gains, but my experience with these on one of my previous cars (Renault Clio 16V) the only thing you really gained is a headache from the decebels eminating from the tail pipe.

The cost of a system including the heat exhcangers, I expect to be fairly costly but a good investment in the long term, but some of the companies I have checked out have wildly different prices and guarentee periods so I dont know what to do for the best.

Can anyone recommend any one to use (prefeably within a resonable distance from Gatwick Airport) or can anyone shed some light on what options are availible?

 

[Guest]

I use an Hayward&Scott system (Basildon), for which they quote approx. 10 bhp more for normal cars, or up to 25 for forced induction (which I have).

I chose the quietest they could set it to, and the sound is not tiring; around town, it is quite quiet, and on a run the engine/supercharger etc. mask it (inside, anyway).

This is a complete system, approx. £1500.00; I was warned that the heaters would not work so well, but have noticed no difference (but, the best way to get more warm air has always been to run on high revs for a short while, as the 'supercharged' exhaust seems to be hotter anyway).

Apart from the extra noise (my neighbours have not complained, which is good), it did seem to rev easier after it was fitted. I assume that, when the air was being forced in, the old exhaust was not letting it out as fast as it would have liked. The new system, which is equal length, with no x-over pipe, is a more 'open' system.

 

[ClubSport 911]

Dan

Contrary to urban lore, the SC does in fact benefit from a free-flow exhaust with equal length primary manifolds. The scavenging effect is pronounced on the 3.0litre due to the overlap on the cam timing so free flow exhaust = better inlet breathing. My friend did nothing but fit SSI's, and the "after" Dyno was +18bhp.

not bad for £1000... (or is it ??)

All the best

Steve

 

[daro911]

ORIGINAL: engleflick

I have got to replace the heat exchangers on my 1980 911 SC, as they are rather rotton. So I thought I will replace them (and the rest of the exhaust) with a stainless steel version, but on looking around for the best type I am now totally confused as to what to do for the best.
*****************************************************************

Like John said I too had a Hayward&Scott system (Basildon), fitted on my 1989 Speedster and the sound was awesome. Certainly not too loud, never boomy or droning at any rev range just finished the car off perfectly and of course a 3" Dia Stainless end pipe is what these cars should have had from day one.

Now on my current 3rd Boxster, having experienced a Hayward&Scott system twice on my first 2 examples, both did suffer with a droning boomy sound between 2200-2800 rpm which also happens to be bang smack at the 75-85 mph motorway cruise speeds. Totally unacceptable with hindsight but apparently the exhaust system on modern kit is much more than just an exhaust as we know it. Both my Boxsters a 2.5 then a 3.2 sounded very TVR like in sound and volume! upto 3000rpm after which the sound dropped off drastically.

So for Boxster No.3 I spent double H & S type money and invested £1000 in a Roock Exhaust and I was guaranteed two things or all my money back.

1) Sound would be very Ferrari 355 like, zero boom just pure music to the ears

2) Zero performance difference ie I will not lose a single bhp. Apparently on modern cat cars changing the exhaust can prove a recipe for disaster performance wise as well as boom wise.

I am glad to report that both promises proved 100% true and I am very pleased with my current exhaust investment and just wished the factory could hear what I have under my hood cover []

 

[bones]

ORIGINAL: ClubSport 911

Dan

Contrary to urban lore, the SC does in fact benefit from a free-flow exhaust with equal length primary manifolds. The scavenging effect is pronounced on the 3.0litre due to the overlap on the cam timing so free flow exhaust = better inlet breathing. My friend did nothing but fit SSI's, and the "after" Dyno was +18bhp.

not bad for £1000... (or is it ??)

All the best

Steve

Steve is absolutely 100% right. The tried and TESTED way is to go back 10 years and fit equal length headers. If you want to pay a fortune choose SSI (unbeatable quality and performance) but no different in performance terms from the stock early heat exchangers. Couple this this with a real performance exhaust and you are in for a sizeable bhp increase because having lost that pile of junk Porsche felt obliged to fit as an exhaust for the SC, at last that gem of an engine can breathe.
I don't drive my car much in the winter so stainless systems are a money drain I can't justify . I have just bought a pair of almost unused '73 heat exchangers for £180.00, just need bead blasting and re-coating...£30.00. To complement that I am having built as we speak the best performance exhaust available for the SC the TRIAD WEST 2 in 2 out exhaust rated at 90db and a significantly freer flowing exhaust than anything else out there. If you go to the site there are dyno' figures there with a long comparison list. Although the test car is a 290bhp Carrera 3.2 from my correspondence with users in the U.S. the performance increase with an SSI type exhaust (equal length) is impressive.
Whilst I know H&S to be quality exhaust builders I doubt they achieve what Triad do. If noise is an issue then do what I do with my current Bursch (which gives no performance increase but sounds good) is drive respectfully of others where appropriate. If your neighbours can't put up with the small inconvenience of you coming and going remind them it's a free country still.
To complete a conversion to equal length headers and freer flowing exhaust in stainles steel you will need two oil pipes nuts bolts and gaskets.
You are looking at HE..£650-800
Exhaust £250-300
Two oil pipes £100-150
Gaskets etc £25.00 approx
say £1200+vat add fitting or do it yourself.
So far my way is costing £575 inc fitting as I/Porsche buddies are doing it.
Good luck, if you want an in depth chat email me for my phone no. but Steve is right equal length pipes on an SC equal performance gains.
Complementary mod's to this set up are a backdated heating system, deletion of the air pump and air conditioning if you have it.

 

[Guest]

If your neighbours can't put up with the small inconvenience of you coming and going remind them it's a free country still.

Oh er, on slightly dodgy ground here ! It never has been a free country !

I live in a block of flats, and so have to drive within a few feet of a number of flats, so have kept my exhaust noise down to a minumum. I don't like getting woken up in the middle of the night; why should they ?

 

[bones]

You're right of course generally but so AM I ....lol.....nothing dodgy about about saying this is a free country , it's still a democracy in the broad sense of the word and there are many places around the world where we couldn't discuss this. As to noise I've lived in these flats for seventeen years and I haven't had a complaint yet, indeed everybody loves me. I don't have open megaphones you know, now there's an idea!
I hope you will be coming to my 'get Bones' engine and transmission out post Xmas gathering?
PS as you are a 917 fan (me too) do you have a book called 'Porsche 917 The Ultimate Weapon' If not ask someone to get it you for Xmas.

 

[Guest]

I hope you will be coming to my 'get Bones' engine and transmission out post Xmas gathering?

What's this, what's this ?
Making plans without telling me ? Humph !

When ?

 

[bones]

Don't sulk John and sadly it's not a party, I've been thinking ahead to the after Xmas period and that is when I will be taking my engine out here to fit the new tranny and refurbish and replace a few hard to get to engine parts. I'll put a more detailed post in my original 'need help thread soon'. I thought you'd like to come over if it fits in with your schedule as it's not often you get to see the engine out and have a good nosey around because they are usually in a workshop.

 

[engleflick]

Thanks to all who have answered my question, I think I am begining to like this forum place, normally every time I start to talk 'Porsche' I can see everyones eyes glazing over, and hear them saying 'oh no he's going on about the car again!'

 

[Guest]

as it's not often you get to see the engine out and have a good nosey around

Luckily, my garage lets me wander around, and under, the cars they have in, so I get to learn a lot about how the cars are put together.

It's one thing to see it in the manual, another to see it in the flesh and be able to ask 'what's that ?'

So, count me in.

(No party ? Humph !)

 

[bones]

Maybe we should start a North London region then we can have our own get togethers there must be plenty of us.

 

[Guest]

North London - do you mean north of the 'dark water' ?

Some of us live in West London, and don't necessarily want to be associated with the 'norf Lunnun' mob; we have our standards to maintain, don't yah know ?

The very idea ! Humph !

Disgruntled of LBHF

 

[bones]

OK I'll start my own but when it's the biggest and best don't say you weren't invited.

 

[Guest]

Interesting read about your exhaust system. I too need 2 heat exchangers but exhaust seems ok. I am changing my SC next year 9to another or carrera) and think SS HE is OTT. Can you give me more info on your system- where to buy, cost etc.

Cheers
Malc.