Performance exhaust in the UK [Archive] - SaabCentral Forums

: Performance exhaust in the UK


john-w
6th March 2002, 03:31 PM
Just recieved this estimate for a custom built exhaust, thought a few in the UK could be interested!!
Thank you for your email.

We specialise in Longlife custom built and fitted exhausts, on any car, in best quality 304, non-ferretic stainless steel.

This unique service gives the customer a complete choice of style and sound for his exhaust, which comes with a life of the car guarantee.

The average time taken to craft and fit a system is 3 to 4 hours, by appointment at a Longlife centre. You would need to bring your car to our Longlife centre in South London.

The price for a high quality, custom built Longlife 304 stainless steel system, for your Saab 900, from the existing down pipe to rear, would be 289, including fitting and VAT, with a 2 rolled out polished stainless tail pipe. For this car we would normally fit a 2.25 system, but if you wish you could have a 2.5 system. However bearing in mind you need back pressure on a turbo, and you intend to leave out the middle box, we recommend you stay with 2.25.

We have a selection of special tail pipes, up to 4 rolled out, 5 rolled in, ovals, DTMs etc., which would be at extra cost.

All our systems are free-flow and the main gain you can expect with a complete system, is to improve fuel economy by approximately 10%, because the engine will breathe better. The engine will produce between 4% to 8% more BHP and the torque will increase by 2% to 4%.

If you would like any further information please ring me on
freephone 0800 27 999 00. You may like to look at our new website http://www.exhausts.uk.com if you have not already done so.

We look forward to hearing from you.

Regards.

Robin Abrey.
Longlife Exhausts.

Jo K
6th March 2002, 03:35 PM
Well that sounds like a very professional response!

Pity I'm not a bit closer... :sad:

tandino
6th March 2002, 03:37 PM
Hi John,
Try to find out if they will do a group buy, i would be interested in a 2.5 inch system with a oval tailpipe!(like the original but larger as the original looks weedy!).
Im sure there would be a few people from this board in the UK who would be interested!
Cheers Big Guy!
Pete.

john-w
6th March 2002, 03:41 PM
On the tailpipe thing i would prefer the carlson twin outlet look to keep with the originality of the car!!

Keith
6th March 2002, 03:53 PM
Hmmm.. why do you 'need' back pressure on a turbo, surely you are after the biggest pressure drop you can get across the turbine?

john-w
6th March 2002, 03:58 PM
I wondered if that was right, thought I would wait for someone clever to come along and confirm or dispute that statement!!

Alex
6th March 2002, 05:03 PM
The back pressure is used in part to help the pressure balance across the turbine oil seal. Too little back pressure and you tend to find the engine oil joins the exhaust gases flowing out of the car, and then coats the rear bumper.

Replying to the above post doesn't mean I'm clever though.

Location is good, I drive past their head office to get to my temporary furniture storage facility!!

_________________
Black '88 T16S 2dr

<font size=-1>[ This Message was edited by: Alex on Mar 6, 2002 9:05pm ]</font>

90t16Saero
6th March 2002, 06:04 PM
I've emailed them tonight, i want a full system. I'll let you know their response.

<font size=-1>[ This Message was edited by: 90t16Saero on Mar 6, 2002 10:05pm ]</font>

john-w
6th March 2002, 06:21 PM
well if any of you out there are serious about getting a new exhaust we could try the group buy suggestion and see how much we could get the price down.
Anybody interested send me a private message!!

Alex
6th March 2002, 06:39 PM
Unfortunately I already have a performance system. I don't think the problems with low back pressure really affect Saabs as the turbo exit elbow is so restrictive anyway.

Wonder if they can be persuaded to make a full 3" system from the turbo exit onwards?

Alanb
7th March 2002, 04:01 AM
John,

Good price but I really want the down-pipe. I think that's where the big gains are to be made.

Alanb

Keith
7th March 2002, 05:51 AM
and the exhuast manifold, I hate that thing.

Johann F
7th March 2002, 06:17 AM
The back pressure statement is suspect - on a turbo car back pressure is confined to the manifold before the turbo. In order to get the turbo working at maximum efficiency the idea is to get the maximum pressure diferential between the entrance and exit of the turbo on the exhaust side. That is how they work - any restriction down wind of the turbo reduces this differential and you are not getting the most out of your turbo. Seals will leak if they are worn and a restrictive exhaust may hide the problem and an unrestrictive exhaust will expose it.
There is always an advert in The Saab driver magazine for stainless systems - they offer a very cheap 'cat back' system for turbo cars ( can't remember the price though) this is essentialy what is on offer here and it's pretty easy to join an OE down pipe to a Cat system. I'm not convinced by the mpg/power claims unless you are replacing a Cat system or a poor non OE system - Saab OE exhausts (esp without cats and center sections) are pretty good and as Alan points out the biggest gain comes by relaxing the tight bend as it exits the turbo.

Trevor Cockayne
7th March 2002, 11:32 AM
The Back-Presure thing it true if you remove all back pressure your turbing will spool quicker but will not go as far due to the imballance like strapping a house brick to your frount wheels also back presure is required to hold the oil seal in place the turbo elbow will not create any back pressure just impend the exhaust flow the best system would be to eliminate the turbo elbow and relocate the batt to the boot

Trent saab sell 2 5/8 system from turbo back and have no problems

Keith
7th March 2002, 01:56 PM
How is removing back pressure on the turbine going to unbalance it centrifugally?

I remember a quote from somewhere about house bricks and wheels....I think it was on the turbo technics site.

They were talking about turbo's that they have seen that have not been balanced correctly when they were built in the same way as you would balance a tyre to cure a vibration.

The balance Alex is referring to is reducing the pressure differential between the oil pressure in the turbo against the exhaust pressure.

The turbo elbow is restrictive so it will create a higher pressure area upstream of it which will help the pressure differential across the oil seal.

<font size=-1>[ This Message was edited by: Keith on Mar 7, 2002 6:02pm ]</font>

Alanb
7th March 2002, 05:39 PM
Keith,

Have you ever taken the manifold off? There is an enormous restriction near where the erg thing screws in. It must reduce the aize of the passage by 30%. Totally absurd. A no cost fix is to chisel it out and then grind down. This gives slightly better spool up and a bit better top end.

Alanb

Alex
7th March 2002, 05:46 PM
Most turbine systems use pressure on the outside of seals to help keep the oil in where its wanted.

Atleast, the oil systems we design at work use this principle (admitably our engines are slightly larger than a T3) and we've been building them since the late 40s early 50s.

eric_b
7th March 2002, 06:03 PM
Since you guys are on the topic of backpressure, will it be damaging to my car to drive it about 30 miles with the cat cut out (I plan to have a piece of straight pipe welded in, but have to drive to the a shop a ways away to get it done).

What about just removing the cat? I think that this will certainly reduce the back pressure, but not to an extent were these oil seals spoken of will lose their seal, especially since the UK models didn't even have a cat form the factory.

Well, sorry, forgot that this post was on performance exaust for UK cars, in that case, I really have no idea, though it seems that there would still be little back pressure on the back side of the turbine, most would be in front of it were the air is pileing up in front of the blades, and after them... well, I just can't see how back pressure is relied on for keeping oil in.

-eric

_________________
1984 900 turbo (http://www.saab-900.com/gallery/3_door_hatch/g3h_ericB.htm) with lightly tweaked APC, SVH kit, K&amp;N pop-charger, Dual-stage Water Injection, and 5th fuel injector mod.

<font size=-1>[ This Message was edited by: eric_b on Mar 7, 2002 10:16pm ]</font>

Johann F
8th March 2002, 06:49 AM
Trevor,
If you need back pressure (down of the turbo) to hold oil in the bearings then the seals ARE worn - oil pressure is much higher than turbo pressure - think about it! If you have back pressure/restriction downstream of the turbo eventualy the turbo will slow down as pressure equalizes each side of the turbo - the opposite of what you claim will happen ie you get good low down boost and poor high boost.
Eric,
I have removed center boxes and Cats from my T16's with good results in each case. Better high RPM boost and power, reduced fuel consumption and better spool up. Later UK cars came with Cats but a different fuel ECU system (lucas)The only problem I had when I took the cat off my 91 was a slight reduction in off boost response - this has been noted by several people. The solution is to add a bit more fuel via an ECU chip or,as I did, use a RRFPR. This may only apply to the Lucas system though - with the Bosch LH you may be able to leave fueling alone.

Trevor Cockayne
8th March 2002, 12:19 PM
keith, the imballance is in the shaft due to lack of back pressure if you don't trust me take you exhaust eldow off your turbo and drive your car up the street !!

John F, yes the oil is under higher presure than the exhaust system but you will increase lateral movement in the shaft and cause your oil seal to become dammaged a lot quicker
_________________
1984 T16S Black
1985 T8 Auto Blue

<font size=-1>[ This Message was edited by: Trevor ****ayne on Mar 8, 2002 4:23pm ]</font>

Alex
8th March 2002, 12:43 PM
I did say that the back pressure in the exhaust down stream of the turbo is used to help the oil seal in its job.

And yes its a trade off, lower the back pressure the faster the turbo spoolup but it becomes more likely that there may be problems with oil leaks.

Johann F
8th March 2002, 02:53 PM
Sorry - this is getting very confusing. The only back pressure of consequence is that in the manifold before the turbo - as the gases squeeze out of the housing into the exhaust downpipe they force the wheel back against the housing - this has nothing to do with exhaust system back pressure downstream of the turbo. Seals get worn due to contaminated oil, lack of oil or a shaft that is not dynamicaly balanced in rotation. Indeed the classic indication of leaking shaft seals is smoke at idle when there is no or little pressure in the manifold to hold the oil in - again nothing to do with exhaust backpressure. The seals on the shaft are like piston rings - they are designed to cope with lateral movement and the turbo is itself designed to withstand the imense pressure in the exhaust manifold under boost which forces the spinning wheel up against a thrust bearing - changes in exhaust system flow or pressure cannot possibly introduce extra stress in this area. The other cause of lateral movement is between shifts - the BOV helps here as it prevents the 'push' from the other side.

Trevor Cockayne
8th March 2002, 03:27 PM
It is not suppost to be easy buy a book on turbines and all will be revield

Nuts
8th March 2002, 04:33 PM
I run a full abbott system, and I would hope that it reduces back pressure on the turbo an amount more than the standard system, that's what I bought it for. My turbocharger is also a year old. I have no oil leaking past the turbo.

Makes me think it's more down to worn/old parts being used as examples.

I have a book on turbo chargers as well :smile:

Keith
8th March 2002, 08:13 PM
Trevor, just what do you expect to happen when you remove the elbow off the turbo, apart from cooking the battery.

It sounds like you're expecting it to fly apart because it suddenly becomes dynamically unbalanced.....

How much back pressure is this exhaust system causing?

http://www.aardvark.co.nz/pjet/turbine1.htm
http://www.aardvark.co.nz/pjet/video/theturbine1a.rm

Johann F
9th March 2002, 06:36 AM
Interesting comment about Amsoil 0w-30.

tandino
9th March 2002, 08:07 AM
Well while im relatively new to turbo's after having tuned normally aspirated engines in previous cars i would expect the turbine to provide more than enough back pressure in itself, if not then why did the Touring Car Sierra RS 500's run a huge side exit exhaust system with NO silencers at all, the ID of the pipe was at leat 4"'s, surely Ford Motorsport knew enough about back pressure etc when they designed the exhausts for these huge monsters.......
Pete.

_________________
Black88t16s,5hagged gearbox and sporting a 'baby on board' sign in the rear window-never to wheelspin again.........

<font size=-1>[ This Message was edited by: tandino on Mar 9, 2002 2:47pm ]</font>

Trevor Cockayne
9th March 2002, 10:39 AM
if you speak to the garratt people they will tell you the same you can reduce back pressure but not eliminate it

Johann F
9th March 2002, 05:42 PM
Trevor,
So if the Garrett people say this - are they saying it's a good thing or a bad thing to have backpressure down stream of the turbo - ie a restrictive exhaust system?

Trevor Cockayne
9th March 2002, 09:50 PM
they have no problem reducing back pressure in the exhaust system but eliminating it is a bad idea as i did alot of research because i was going to get a 3 inch exhaust half way and then twin 2 inch pipes form the middle box to eliminate backpressure but not to make a horrid noise

Keith
9th March 2002, 10:04 PM
So are they recommending leaving some back pressure as an aid to noise suppression?

I can see how that helps take out pulses in the exhaust gas, however the turbo does a pretty good job of doing that anyway.

I am having a hard time believing you need any post turbo exhaust restriction to aid the performance of the turbo.

Johann F
10th March 2002, 05:34 AM
Trevor,
I'm sorry - you are not making this at all clear - are they saying it is a bad idea or just physicaly impossible to do?

Trevor Cockayne
10th March 2002, 08:04 AM
NO i was thinking of getting a exhaust system with no back pressure and they said it was a bad idea to eliminate back presure but reduceing it was ok

Trevor Cockayne
10th March 2002, 08:09 AM
also it depends if you have a T3 or a mitsubushi TE-05 as the mitsi units don't suffer from this probelm

Johann F
11th March 2002, 04:34 AM
Trevor,
This still does not add up - what degree of back pressure is acceptable? -
I suggest it is impossible to make exhaust back pressure zero ( unless you remove the exhaust totally and no one is suggesting this as a 'practical' solution) as any size of exhaust will give some back pressure.
When you say it depends on the type of turbo this is a different issue - these turbo's difffer in the way that the wastegate gases are integrated into the main exhaust outlet - please explain how this is influenced by changes in backpressure.

john-w
11th March 2002, 01:38 PM
I spoke to Robin Abrey of Longlife Exhausts today he offered a 10% discount on the exhaust price if we could get 4 people together in the same week!

I also asked him to look at this page and post a reply regarding the back pressure issue!

So maybe we will get a response from him shortly.

Paul
11th March 2002, 05:39 PM
I had this sent to me as a private message this evening......

"At Longlife we have a mission statement: "Longlife Exhausts aim to build and fit the best quality custom built stainless steel exhaust, for any car, enhancing performance and economy, surpassing our customers expectations, whilst providing real value."

We do not specialise in a single marque. Longlife exhausts certainly enhance the style, and generally there is a fuel economy gain because of the freeflow absorption silencers we produce.

We do believe that on the Saab LP Turbo cars, some back pressure is desirable, to ensure the piston ring type seals used on the turbo in these cars does not leak, but we are open to correction on this point.

With regard to front pipes, we can of course manufacture and fit these at the same time as the system, but since cost is often paramount, and Saab front pipes in particular go on and on, it is not in the owners interest to replace these. They cost about 90 if done with the system.

With regard to the system bore size. 2.25" NB tube is good for up to 250 BHP, but if 2.5" is used, we advise that the management system should be re-optimised, including the fuel settings, for maximum efficiency.

Longlife will build a system in 304 stainless to the owners requirement, so if you want the restrictive Turbo bend removed, we will do it. If you want a 3" system, we will do it. If you want a rolling road before and after, we will arrange it, at your cost. If you want special tail pipes we have them.

We are here to provide you, the enthusiast, with real value for money. Give us a club order and the individual price will be reduced.

Robin Abrey.
MD Longlife Exhausts."

tandino
11th March 2002, 05:59 PM
Sounds like a reasonable chap, i would be interested in the exhaust next month or so, who else would be then?
Pete.

Alex
11th March 2002, 06:14 PM
Oh dear, capable of making 3" systems. I think my wallet might take a bashing in the near future!

Johann F
11th March 2002, 07:01 PM
Robin's statement says that the LP ( low pressure?) turbo cars have a problem with seals and back pressure - by definition this means the Mitsubishi turbo where as according to Trevor's info from the Garrett experts its the other way round????
Whatever - it's a good price for a good exhaust - I'd be interested if mine was on it's last legs - i will have to have a look!

john-w
11th March 2002, 08:00 PM
well what can i say! that was a great response from Robin, as I only spoke to him late this afternoon!
Well everybody, message me if you want me to arrange something!!

Alanb
12th March 2002, 03:42 PM
I'd like to register my serious interest

Alanb

eric_b
18th March 2002, 05:59 PM
I just cut the cat off of my (what appears to be) factory exaust. I measured the pipe and it has a 2.5 inch outside diameter, that is pretty darn big in my opinion. I wonder if my car, though old lady owned, has some form of an aftermarket exaust on it? The 2.5 inch pipe runs from the turbo elbow to the tip, never reducing in size. The exaust also shows no signs of rust or wear, and from what I have read in this forum it sounds as if a '84 900 turbo shoud have its factory exaust rusted out.

I drove the car to the shop where I had the "test pipe" welded in ($20 including parts) and boy oh boy is the saab ever a beast when running 3 feet of 2.5 inch pipe. The vehicle was so loud I could not rev it above 3000 rpms due to the painful noise. I also noticed the turbo is quite loud sans exaust, my friend said he could hear the turbo spooling up while in his car 3 cars ahead of me, and I am happy to report that the turbo sounds to be in perfect health.

I must caution you guys though, without the exaust I had no low end torque, the car was quite sluggish to get going, but once up into the turbo range I could feel a lot more power.

After getting the pipe patched the car runs and sounds great. The note at idle is much louder, deeper and lower than it was before the cat removal. I now seem to have more power throughout my rev range, my turbo spools up noticably quicker, and the car produces such a lovely sound as the rpms climb that I have provoked to drive with my windows down on a rather cold days, just to hear it.

Anyone know any specifics about the saab muffler design? It appears to be quite the high flow masterpiece, rivaling the sound produced by my father's twin glass packs on his V8 F150 (he didn't put them there, they came on the truck), in fact, the lowness of the saab's engine suprises me. I don't think a saab could sound ricey if you tried, it just sounds like it is a much larger engine than it is.

-eric

Janne Selinummi
18th March 2002, 06:34 PM
...Does this all equate to us being unable to use a 3" racing exhaust without damaging
the turbo oil seals? And if lack of back pressure also causes turbine inbalance, why do turbocharged racing cars use the largest exhaust systems available? For example, WRC rally cars seem to have 3.5 to 4 inch exhausts...
So, should I deliberately build some kind of restrictment to my custom 3" pipe when I start the work?

Alex
18th March 2002, 06:48 PM
I would think that the requirements for racing cars are slightly different than for road vehicles.

After all on the WRC cars the anti-lag systems destroy exhaust manifolds, exhaust valves and don't do much good to the turbine, so any problems from the exhaust are likely to be minimal in comparison. Also these cars only have to last 3 days of competition not several years and 1000s of miles of driving.