I seem to be running around in circles here....am i right in thinking 3 hole NA pipes will fit a TT with normal S1 elbow,s (without precats)..also are the auto and manwell pipes the same or not. put simply whats out there without going the divorced elbow route for a LWB auto:confused1:

I've got japspeed decats on my manual Bri and they fit perfectly. 3 Holes as you say, I think the issue is with the autobox sump pan getting in the way. Nothing that you couldn't fix with a minor bit of fettling. I was under the impression that the only difference was between SWB and LWB at the centre sections. I also assume that you wouldn't really want a free flow exhaust with an NA due to the loss of back pressure.

I've got japspeed decats on my manual Bri and they fit perfectly. 3 Holes as you say, I think the issue is with the autobox sump pan getting in the way. Nothing that you couldn't fix with a minor bit of fettling. I was under the impression that the only difference was between SWB and LWB at the centre sections. I also assume that you wouldn't really want a free flow exhaust with an NA due to the loss of back pressure.

 

thats what i needed to know Dave...where it interfered with under the car.cheers

. I also assume that you wouldn't really want a free flow exhaust with an NA due to the loss of back pressure.

 

Oh yes you do.

Oh yes you do.

 

I thought you needed a bit of back pressure for an N/A and a freer flowing one for a TT?

I went for japspeed na decats on a tt manual . 1st they have silencers on them, my thinking is these will cause a bit of back pressure and hopefully keep turbo seals from giving up and smoking. 2nd i didnt want the hasle of changing turbo elbows and snaping 20 year old studs off poss engine out job or drilling for hours .

Exhaust backpressure, the myth

 

There is absolutely no way that the gas pressure in the exhaust system would have any equilibrial effect on a seal which is under comparatively trememdous amounts of pressure from oil on the other side. Because Physics.

 

If your car was smokey after fitting de-cats, it was like it before. You didn't notice because the cats were just doing their job of turning what passed through them into something less offensive.

 

 

Sorry for going on the attack, but all this hocus-pocus surrounding backpressure and oil seals really needs to stop.

I bet 90% of blue smoke is blocked or partly blocked PCV valves...shocking idea to think that 2 small mechanical valves is the stop gate from a pressurised sump direct from the boosted plenum and then rely on a gravity return oil system from the tubs. recipe for disaster!!!

Exhaust backpressure, the myth

 

There is absolutely no way that the gas pressure in the exhaust system would have any equilibrial effect on a seal which is under comparatively trememdous amounts of pressure from oil on the other side. Because Physics.

 

If your car was smokey after fitting de-cats, it was like it before. You didn't notice because the cats were just doing their job of turning what passed through them into something less offensive.

 

 

Sorry for going on the attack, but all this hocus-pocus surrounding backpressure and oil seals really needs to stop.

 

LOL! that provides more Hocus Pocus on cats!! :D

 

first - most standard turbos do rely on a degree of back pressure to maintain a dynamic seal - stagger gap rings are used to prevent this, more info here from a website that builds turbos: http://www.turbodynamics.co.uk/services/turbo-upgrades/other-upgrades/

 

Staggered Gap Piston Ring

A Staggered Gap Piston Ring replaces the standard piston ring seal. It is designed for use in low back pressure exhaust systems where oil weepage into the exhaust could possibly occur.

 

Twin Seal Conversion

Twin Seal conversions pre-date Staggered Gap Piston Rings and are used on older turbochargers where staggered-gap rings are not available. The process involves careful machining of the piston ringland on the shaft and the seal bore area of the bearing housing to allow a second piston ring seal to be fitted. This reduces oil weepage on cars with low back pressure exhaust systems or higher than usual crankcase pressure.

 

As for the cat comment on its doing its job - cats are designed to convert 2 or 3 chemicals (depending on if its a 2 way or 3 way cat) into less harmless chemicals - CO, HC and in the event on a 3 way on most petrol cars - NOx are converted in the cats.

 

A cat cannot convert burning oil smoke into anything else! In fact an excess of this will just kill a cat!

 

Staggered Gap Piston Ring

 

Wake up, we're talking oil seals in the turbo, not piston rings.

 

 

As for the cat comment on its doing its job - cats are designed to convert 2 or 3 chemicals (depending on if its a 2 way or 3 way cat) into less harmless chemicals - CO, HC and in the event on a 3 way on most petrol cars - NOx are converted in the cats.

A cat cannot convert burning oil smoke into anything else! In fact an excess of this will just kill a cat!

Now you're putting words in my mouth. Nobody said anything about converting chemicals.

 

Cats have a presence of form as well as function in an exhaust. You seem like a smart fella, I'm sure you'll figure out why cats mask smoke eventually.

Staggered Gap Piston Ring

A Staggered Gap Piston Ring replaces the standard piston ring seal. It is designed for use in low back pressure exhaust systems where oil weepage into the exhaust could possibly occur.

Wake up, we're talking oil seals in the turbo, not piston rings.

 

 

 

Now you're putting words in my mouth. Nobody said anything about converting chemicals.

 

Cats have a presence of form as well as function in an exhaust. You seem like a smart fella, I'm sure you'll figure out why cats mask smoke eventually.

 

Lol! I'm talking about the piston rings in the turbo - this is what forms the seal:

 

Piston Ring Seals can be found at both ends of the turbocharger. They are designed to keep the exhaust pressure out of the bearing housing, and the air pressure out of the bearing housing.

 

And cats still can't "convert" smoke!

 

And thanks, I am smart! :D

 

Sorry if this contradicts what you think!

Lol! I'm talking about the piston rings in the turbo

 

keep the exhaust pressure out of the bearing housing

Now that's contradicting the pro-backpressure said earlier.

 

And cats still can't "convert" smoke!

They don't. They mask it. Keep thinking, you'll work it out.

 

Sorry if this contradicts what you think!

I could agree with you, but then we'd both be wrong!

While I welcome the discussion can you keep it civil please lads, with less sniping at each other.

 

Cheers.

Steams.

While I welcome the discussion can you keep it civil please lads, with less sniping at each other.

 

Cheers.

Steams.

 

LOL! thanks - but I am really not trying to snipe anyone - just provide info!

 

 

 

Now that's contradicting the pro-backpressure said earlier.

 

 

They don't. They mask it. Keep thinking, you'll work it out.

 

 

I could agree with you, but then we'd both be wrong!

 

 

Ok - lets look at this one step at a time - first it appears you didnt even know the construction of a turbo 10 mins ago or how it works - now you are trying to say my comment on piston rings is a contradiction - the things you didnt even know about on your last post & thought we were discussing the pison rings on the pistons in the block - right?!

 

Ok - they are designed to keep the back pressure out of the turbo - reduce the back pressure & they work the other way - they are a dynamic seal relying on pressure balance either side of the seal. Thats not a contradiction but an understanding of how they work.

 

next - so cats "mask" smoke - please explain how! Smoke is formed by the oil burning in the hot exhaust - cats are a monolith of precious metals with the only possibility of acting as a catalyst to convert previous said emission chemicals into other chemicals - thats it - job done - all other gasses pass through without anything happening! If an engine burns oil or steam forms from a head gasket or oil passing through a turbo & causes smoke then the smoke will just pass though!!!! If you think otherwise then please let me know how!

 

 

PS - back on topic - back pressure as far as performance is concerned is bad (generally speaking). Flow of exhaust gasses is far more important. Back pressure in some instances cab actually be slightly beneficial but on the whole it is the engines enemy for performance. What backpressure can do is change the flow however - there is much discussion & science behind shockwave tuning in an exhaust - using the inertia from the exhaust gas flow from one cylinder to help draw the gasses from the next exhaust stoke on that exhaust. Reducing back pressure will allow the gasses to flow faster & use the inertia to help flow - HOWEVER sometimes reducing backpressure can actually impact this effect in a negative way - its not so much the back pressure reduction that is bad but he way it has effected flow changing this shockwave effect.

 

Im sure someone will disagree but there you go! :p

1) When people say "turbo seal" they are referring to the piston ring seal in a turb, not everyone knows the correct terminology.

2) In the Back pressureMyth link, unless i missed it i didn't spot the differences between a N/A car and a Turbo'd car. This is important as obviously N/A's don't rely on back pressure, however many if not most Turbo'd cars do and that's a fact!

3) For standard and certainly OEM turbo's in a Zed they will have done some serious mileage and may or may have not been looked after with regular Oil changes, Piston ring seals like any component part will wear in time, hence why MANY have decatted and very soon noticed smoking exhaust.

Removing catts alters the back pressure in a Turbo to the point of lessening it, the floating seal is now no longer "sealed" thus allowing oil to burn in the exhaust and cause smoke.

4) I have personal experience being years ago a supplier of turbo's from Turbo tecnics whose reconed and new turbo's fitted on a Zed weeped oil on an already decatted Zed in time.

They in turn designed a breather kit, this only worked on Zeds with a poor PCV system.

Turbo Dynamics supplied as standard on replacement Zed turbo's the "Stagger gap" piston ring seal soley for the purpose to prevent leakage when altering back pressure, something which is needed on a turbo car to help achieve power.

Needless to say for the next 4 years i supplied their turbo's and never seen a single one returned due to oil seapage.

 

Lastly, when looking at serious power cars you often see the exhaust is shortend and sometimes exits at the front wing or under the side of the car, greatly reducing pressure in the system, owners/builders of these cars do so at a risk to the turbo's lifespan and they accept it in exchange for performance.

 

Oh and catts or no catts, you put Oil in a hot exhaust and it's coming out as pure smoke baby, nothing ain't gonna stop that!

 

Smithy

I did post up recently a thread which helped explained alot of this with pictures. Essentially those piston rings in the tub hold oil in, wjen they wear the backpressure from the cat holds that back, and forces the oil down the return. When you remove this, if your breathers arnt right or/and your seals are too worn oil will pass. So your both right in parts. It all has to work together.

I thought you needed a bit of back pressure for an N/A and a freer flowing one for a TT?

 

Its more to do with how the exit the system, different manifolds play apart here in na tuning. Balancing the correct exhaust to say a high torque or high rpm/bhp. To easier flow and it will idle crap, but run lie stink higher up. Its quite complex.

Its more to do with how the exit the system, different manifolds play apart here in na tuning. Balancing the correct exhaust to say a high torque or high rpm/bhp. To easier flow and it will idle crap, but run lie stink higher up. Its quite complex.

 

Thanks for that mate. Your right, it is bloody complex..lol

getting back on track, why don't you want to go divorced elbows etc?

getting back on track, why don't you want to go divorced elbows etc?

 

because i have an allergic reaction to relieving my pocket of the queens finest...think ile just get s/h standed downpipes and knock the cats out and mate them up to my almost aquired Kakimoto single exit:yes:

and one quick one for the last. I had and still have a 1990 man tt . had it decated and ebc fitted. wound up the ebc on prob tired tubs two weeks down the rd . oil seals gone , since had tubs rebuilt with 360 degree bearings and stragght threw pipes. new pcvs and no more smoke or probes. My advised dont decate unless you know how you you tubs are built.

and one quick one for the last. I had and still have a 1990 man tt . had it decated and ebc fitted. wound up the ebc on prob tired tubs two weeks down the rd . oil seals gone , since had tubs rebuilt with 360 degree bearings and stragght threw pipes. new pcvs and no more smoke or probes. My advised dont decate unless you know how you you tubs are built.

 

Cheers for the heads up...Had my last zed decated running 15-16 psi for 2 years,no smoke:whistling: