New exhaust

Matt P · Aug 9, 2004

Hi all , have just discovered that the exhaust on my car needs replacing !Have looked underneath and it looks like the heat exchangers have been replaced for stainless ones.I would like to replace the pre silencer ,rear silencer and cross over pipe with stainless ones (preferably a sports type)Any ideas of a good type available/supplier and will the parts fit to the original exchangers?Thanks
PS if it gets sorted will be taking it to the festival but at the moment it sounds like one of them twin engine prokarts....errrgh!!!

daro911 · Aug 9, 2004

ORIGINAL: Matt P

Any ideas of a good type available/supplier and will the parts fit to the original exchangers?Thanks

Matt give Ian a ring at Hayward & Scott 01268-727256 or email him : sales@haywardandscott.co.uk and checkout website www.haywardandscott.co.uk

I had a very nice system on my 911 Speedster sounded great and looked much better with a 75mm End Pipe

Guest · Aug 9, 2004

How do you tell if the exchangers are stainless?

OEM ones are aluminium so dont rust. Mine would have come up like new if it wasnt for the fact I had a leak inside one of them.

Not to say yours arn't stainless but they may not be.

Cheers

Andy

Matt P · Aug 9, 2004

Thanks will give them people a call to get a price.Didn`t know the OEM ones were aluminium (thought they might get a bit hot!)but will re-check to see, they just looked like stainless that hadn`t been polished.

Guest · Aug 9, 2004

Didn`t know the OEM ones were aluminium (thought they might get a bit hot!)

Hopefully, not that hot, as they have air between them and the exhaust pipe proper (one hopes). Anyway, aluminium can take some heat.

Guest · Aug 10, 2004

Use the seach button here on this forum to find all the previous discussions on exhausts and mods. There is alot.

911sse · Aug 10, 2004

Get a price from

Iain at Specialist Cars of Malton

also

Karl at Design 911

I would go for an 84mm single outlet back box and a sports crossover pipe, makes
all the difference to the sound and you get (seemingly!!) around 4-6bhp.....

Guest · Aug 10, 2004

I would be very, very surprised if OE heat exchangers are aluminium - first I have heard of it anyway. Some exhaust parts are "aluminised steel" which I guess is something similar to galvinised.

I have heard an H&S system (though not one on a Speedster) and it was a great sounding exhaust - but at a price. The H&S system is similar to SSIs (or the pre 74 system) with basically two separate sets of headers with a much smaller heat exchanger on each that converge and head straight back into a 2-in 2-out muffler. Like SSIs it requires backdating of the oil lines and probably heating system. My educated guess is you don't get much change from £2000 once fitted. If you just replace your crossover pipe, presilencer and muffler you are in the red for about half this amount. If you buy SSIs and a stainless muffler you could be done for about £1500 if you buy carefully.

You could do a lot worse then Dansk mufflers in stainless, but beware of reducing the backpressure too much with a 1-in 2-out muffler. The 3.2 likes a little backpressure in order to make torque. Too little backpressure and you may find you need a chip as well. You could also call Simon at Essential Styling. He has done some testing and has some solutions for the lack of back pressure. Basically, there is no easy horsepower on the table for a 3.2 just by changing the exhaust. If you want a sports system, just remember, you are buying it for the looks and sound, not the horsepower.

One last note. I would also avoid replacing the pre-silencer with a test pipe. Anecdotally anyway, these seem to have a detrimental effect on horsepower. For whatever reason, the 3.2 likes a pre-silencer.

If it was my money, I would get a two-piece stainless crossover (its easier to fit than one piece and stainless is less prone to rust in this vulnerable location), a plain galvinised pre-silencer (mine has lasted for at least 5 years) and a single out muffler of your choice (saves cutting the valence and no worries about back pressure with the single outs). Slightly out of left field, but, FVD makes a race single out silencer that is about EUR250 in its catalogue that may be worth a look - should sound good anyway. Its not stainless but again, in my experience, these things last forever. Apart from my crossover pipe that I had to replace last year, my plain exhaust just won't die. I wish it would so I had an excuse to buy something really cool - but it won't.

Richard

3.2_fordy · Aug 10, 2004

I changed my exhaust to stainless steel 2 years ago, if you are after a OM copy, I would recommend

Blue Flame Performance I only paid £377 for the full system up to the heat exchangers. the company

makes systems for most high performance cars and bikes, So If you dont want to to pay the earth for a

bit of noise I recommend tham

Matt P · Aug 10, 2004

Thanks all! Now too decide which route to take (should keep me busy for a couple of hours!! )

Guest · Aug 10, 2004

Couple of hours !!! Are you crazy man??? You need at least a couple of months to make a decision of this magnitude....

Jacob · Aug 10, 2004

As ever, you have alot of good advice to follow.

I changed my exhaust for a SS Dansk 84mm silencer and sports pre silencer. Just to repeat what is said elsewhere - I did NOT do this for hp, but more for that unmistakeable howl. Very pleased with the end result.

Guest · Aug 11, 2004

Gentlemen! Can anyone tell me if there is any weight advantage in using an all-stainless steel exhaust system (heat exchangers, cross-over pipe. pre-silencer and sports silencer) over a mild steel system. I live in Athens where we do not have any salt or humidity problems compared to the U.K. so my interest is purely performance (lighter rear end) related. My car is a German spec '89 930/25 (9.5:1 CR) with an OE catalytic converter (217 PS DIN). Options I'm considering to improve performance are a) the all stainless system referred to above with a chip (Steve Wong, JZ Machtec, Wayne Schofield, Ninemeister), doing away with the catalytic converter, b) having German tuner Lenz near Munich modify the induction system (see Lenz.de) with an enlarged throttle body, chip, sport cat (100 cell), sport exhaust for a claimed 260 PS for 5,500 euro (approx. 3,700 pounds) and c) fitting a PSI- Motorsport (Belgium) kit with hot film sensor, sport exhaust, conical air filter and chip for 3,500 euro (2,300, pounds) giving a claimed 255 PS. I estimate cost of first option at 2,000-2,300 pounds and performance gain of 20 to 25 PS i.e. approx. 240 PS at flywheel.

Your advice/opinion/suggestions gratefully sought.

John

Jamie Summers · Aug 11, 2004

John,
Starting with the lower compression / lower hp Euro spec engine, realistically the most that a de-cat / exhaust / chip combo is going to do is get you somewhere close to 'Rest of world' spec i.e. 231 bhp. In order to get anything in excess of that you would need to have the engine rebuilt to R.O.W. spec - not really financially viable. It would probably work out cheaper to sell you car and buy a R.O.W. one. Certainly starting with a fresh R.O.W. engine 240 bhp is achievable. If you went for every trick available i.e. re-chip / exhaust / bigger bore throttle / backdating heating system / hotfilm - assuming you were able to get this all set up so that the mods were not cancelling each other out (not as easy as it sounds) then concievably you could get to 260 bhp. But frankly why bother when you could invest the same money by buying a 3.6l engine to drop in which would have an easy 250 bhp anyway or a supercharger giving you 350bhp or sell the 3.2 and upgrade to a 964 ...........

The long and short is that there is no cheap horsepower to be made from a 3.2 engine.

On the weight front if you went for an SSI system (smaller heat exchangers and back-dated heating system) you would save a bit of weight, but not a huge amount. Big weight savings come from swapping the heavy bumpers for lightweight fibreglass swapping the electric seats for lightweight race seats and dumping lots of the sound insulation. Much more than that gets expensive again (fibreglass / carbon body panels, perspex windws etc.) - all of this really isn't worthwhile unless you are trying to build a racecar.

HTH

Jamie

Guest · Aug 11, 2004

IMHO all of those horsepower claims have a degree of snake oil to them - I think they are all somewhat optimistic.

I will try to send a more detailed reply when time permits.

Richard

Guest · Aug 12, 2004

Jamie and Richard, thank you for your prompt replies. My Porsche dream has always been to build a hybrid 911 combining the looks of a 2.8 RSR (see cover of October 1999 911 & Porsche World) with a 993 3.6 engine i.e. a lightweight classic car with modern, torquey, reliable mechanicals. My efforts are currently being stymied by a) the pathetic state of the Athens Stock Exchange and the ever increasing fear these megalomaniac Olympic games are going to further weaken the economy (and my investments here) and b) the fact that my Carrera is a 58,000 miler in virtually new condition (an ex-Adrain Crawford car like yours Jamie, if I'm not mistaken) which I'm loathe to start messing around with, with regard to lightweight bodywork modifications. Based on what I've read on the Pelican, Rennlist, PCGB and Pistonhead websites, as well as an article on the Lenz upgrade in the August 2000 edition of 911 & Porsche World, I gained the impression that the outputs being claimed quoted were not too unrealistic, especially considering that the American 3.2 Carrera's are low compression versions like mine, and that Lenz is a German tuner also familiar with catted engines. However, as you well know, a great deal of the pleasure of owning these cars is in doing the research into improving the car through websites like this one, and benefiting from the experience of those who have gone before you. Thank you in advance for any further advice.

John

Guest · Aug 12, 2004

ORIGINAL: glyfada

Gentlemen! Can anyone tell me if there is any weight advantage in using an all-stainless steel exhaust system (heat exchangers, cross-over pipe. pre-silencer and sports silencer) over a mild steel system. I live in Athens where we do not have any salt or humidity problems compared to the U.K. so my interest is purely performance (lighter rear end) related. My car is a German spec '89 930/25 (9.5:1 CR) with an OE catalytic converter (217 PS DIN). Options I'm considering to improve performance are a) the all stainless system referred to above with a chip (Steve Wong, JZ Machtec, Wayne Schofield, Ninemeister), doing away with the catalytic converter, b) having German tuner Lenz near Munich modify the induction system (see Lenz.de) with an enlarged throttle body, chip, sport cat (100 cell), sport exhaust for a claimed 260 PS for 5,500 euro (approx. 3,700 pounds) and c) fitting a PSI- Motorsport (Belgium) kit with hot film sensor, sport exhaust, conical air filter and chip for 3,500 euro (2,300, pounds) giving a claimed 255 PS. I estimate cost of first option at 2,000-2,300 pounds and performance gain of 20 to 25 PS i.e. approx. 240 PS at flywheel.

Your advice/opinion/suggestions gratefully sought.

John

I guess I am sceptical about the hp claims because you have to ask yourself "where is this horsepower coming from?".

You are starting with 217hp and to get to UK 231hp you would need to change to euro high compression jugs (love that word), no cat and euro chip. None of the options you are considering require change of jugs so in this respect you are already behind the UK spec engine.

A stainless exhaust with no other changes gives you zero horsepower. The anecdotal evidence from Pelican suggests that with the Steve Wong chip, you might get to say 225hp. I think that is a realistic expectation - you may get a little more but I personally doubt it. There are a bunch of us running SW chips here and the common consensus seems to be that the cars run very nicely on the chips (some drivability issues are much better), but it is very hard to say that the cars feel conclusively faster. Wayne's chips may do a little better again. It seems as an outsider looking in (and I am happy to be corrected) that the best results Wayne has had are with Clubsports (blueprinted motors that seem to make more hp anyway) or race cars (with fresh motors). Most 3.2s underform compared to factory specs so if you can get back to even factory hp numbers you are actually doing ok.

What are Lenz offering. My German is not so hot, but it seems like a sports cat, a chip and an enlarged throttle body. The sport cat only gets you up to par with a std non-cat 3.2 exhaust (perhaps they offer a sports backbox as well). There chip and exhaust might get you to say 225hp. The enlarged throttle body is a red herring. The throttle body is not a point of restriction in the intake tract. The standard one is big enough for at least 250hp. Most tuners acknowledge that you don't need a bigger TB until you are pushing closer to 300hp.

What are PSI offering? Seems to add a hot film sensor on top of the above but no enlarged TB. Talk to SW about the hot film sensors. He reckons 6hp only IIRC.

So, I don't see any of these options pushing 250hp. I think you are more like 230-235hp. I may be pessimistic, but it seems like you are willing to drop a fair chunk of cash on the table and I would hate to see you disappointed. My opinion (and its only an opinion) might change if some of these guys offered to dyno before and after to verify the changes (like Wayne does). For this type of money, I would be thinking seriously about real mechanical mods such as new cams - this with a chip and a non-cat exhaust with single out sports back box would be a nice engine. If you can spring for new jugs as well (or alternatively), you can go 3.4 with high compression and have a very nice 250+hp with bags of torque. Your £3500 cheque to Lenz gets you close to this. A left field suggestion might be to look at shorter gears. If you just changed 3 and 4 you would have a nice close 2-3-4 with a still relaxing 5th. While you are in there you can replace any worn dogs and synchros and mybe go for a lighter weight flywheel and new clutch. Just a thought.

BTW, I don't think there is any weight advantage in going to stainless exhaust if you compare like-to-like. A sports system with less baffling has less metal presumably so may be lighter.

You should send you original email to SW - he's a good guy and has lots of experience with different set-ups including hot-film and other mods.

HTH

Richard

bones · Aug 12, 2004

John if your car is in virtually new condition it doesn't make sense to tear it apart. Sell it and put the money towards building your own special 911. Find a good donor and go from there. You are obviously looking in the right places for help, it's just a matter of seeing through the misinformation and learning how to get the job done properly.

ClubSport 911 · Aug 12, 2004

One last note. I would also avoid replacing the pre-silencer with a test pipe. Anicdotally anyway, these seem to have a detrimental effect on horsepower. For whatever reason, the 3.2 likes a pre-silencer.

I'm interested on this one. I have heard much the same. One day, I think it would be great to pay for a dyno test with A vs B vs C etc on inlets, exhausts, petrol, chips, Slick 50, Ecotec etc ...If we added the cumulative effects / claims, we'd have a 500hp 3.2 [

]

Anyhow, regarding the back pressure issue, then I heard similar, although different - namely, the insertion of a straight thru pipe reduced HP, but this can be re-gained only if re-mapped. Furthermore, only the high rpm is improved - low speed torque is something I've yet to have confirmed as recoverable by the re-map.

Theory has it that the cam overlap on the cooking 3.2 is minimal, so exhaust improvements do not always translate readily into big HP gains - unlike the SC. Also, we're now into limiting factors like the port area on the head etc.

Good topic. (still wished I had a private dyno to play with all these ideas)

ClubSport 911 · Aug 12, 2004

So, I don't see any of these options pushing 250hp.

I have some interesting "statistics" for the audience.

There is a CS on the register making 247 engine HP, with a re-map, and nothing else - not even on Optimax.

Another car on the register (in the space of 2 years) lost, then re-gained about 10hp - on the same dyno [&:] - 241hp - straight from the box.

Finally, one owner has had a re-map. Thought the result was fantastic, and to quote "Over 4000, the power really cut in"..

He had it dyno'd and the gross HP was about 15hp down @ 220ish. It transpired he was experiencing a massive reduction in torque below the 3.2's 4000rpm sweet spot. So, when he hit this rev range, the power jump felt enormous, and it felt faster. A bit like putting expansion chambers on a 2 stroke, and not re-jetting.

He has since had the car re-mappped and is making 244hp - no other modifications.

So - all a bit subjective isn't it ?

Thoughts...