n/a exhaust system

hey guys, wanted some info on my n/a system.

it appears i have a standard exhaust system with a blitz nur spec backbox on my 95 n/a.

i can see there is a cat just off the manifold, and further down the system (roughly level with the rear seats) there is what appears to be a midbox, now i see people talking about 1st cat and 2nd cat on here... does that mean the 'midbox' is actually a cat? as i was contemplating removing it and fitting a sports midbox to amplify the sound slightly.

also what is best for a n/a, the system that splits off into two before it enters the backbox or a continuous single bore?

what difference does it make? louder? better economy? better performance? as my nur spec is a twin pipe back section.

also what is regarded as a good system on the n/a? ive always wanted a angled hks hi power system, but as the car came with a pretty much brand new nurspec i feel a bit tetchy about changing considering how nice it sounds! but ive never been a big fan of slash cut designs!

There are 2 cats yes. the one under the drivers seat area is the second cat. You cannot buy an after market exhaust system that will accommodate the twin pipe blitz back box as that is intended to be used with the stock system only. Better off selling and getting a whole new single pipe cat back and see if you like the sound level before you go removing the cats. You wont see much performance increase with exhaust mods on an N/A.

Stock exhaust - Mid section and rear back box

Cats - 1st cat is the smallest nearest the engine on RHS of pic.

From your description it sounds like you have the stock exhaust with a Blitz NUR S back box fitted. If you want to fit a new mid section I'd suggest selling the back box and buying a complete cat back exhaust (everything thing from the cats back).

Nearly all aftermarket cat back exhausts are a single pipe through to the back, there are a lot of different makes and models available.

Also, you need to consider MOTs.

I have a double decat exhaust (think its a Chris Wilson jobbie) with a Nur Spec back box. During MOT time I put back one of the cats to pass emissions.

What year is your N/A? Pre July 1995 doesn't need to pass emmissions test.

What year is your N/A? Pre July 1995 doesn't need to pass emmissions test.

How come? So I can do a double decat without hassle?

Because the cars are imports and not domestic, they have slight emmission differences. Basically, imports between Aug 92' and July 95' that are not in the Service Exhaust Emission Standards for Road Vehicles book, then they have much less stringent testing.

Below is a copy from a thread somewhere on here that pointed this out to me.

“The lack of a catalytic converter is not an automatic fail in itself, but a vehicle may struggle to meet the required emission limits without one. Prior to 31 July 1992, a spark ignition engine is required to meet limits of CO

Emissions testing covers both Diesel and petrol engines.

There are some general considerations:

One important issue must be cleared up straight away. There is no requirement for a catalytic converter to be fitted to any vehicle, regardless of its age. It is however the most popular way of ensuring engines meet the emission legislation. The MOT test is testing the emissions from the tailpipe and if those emissions meet the standard then the vehicle passes. The term 'cat' test is inappropriate, the correct term is 'advanced emission test'. Its not the 'cat' that's being tested. There are a number of vehicles which are subject to the 'advanced emission test' but are capable of meeting the requirements without the use of a catalytic converter.

Kit cars and amateur built vehicles are regarded as pre 1st August 1975 vehicles for the purposes of MOT emissions testing and are subject to a visual check only. The age of the engine is not taken into account. SVA(single vehicle approval) introduces some problems and these are complex, the SVA manual is the source of information. In a nutshell all vehicles get a "visual check" and vehicles first used after 1/8/75 or with an engine manufactured after this date get a metered check or a CAT test if they are listed in the emissions handbook or are on the emissions tester database. After August 1995 they get a CAT test. Amateur built vehicle SVA emissions tests are based on the vehicle build date unless there is proof that the engine is earlier. If a date cannot be determined, until 31 March 2001 they will get a non CAT test. From the 1st April 2001 the effective date will be assumed to be 1st August 1997, i.e they will get a CAT test unless there is proof of the date of manufacture of the engine. Also, dual fuel (petrol/gas) are tested in both modes.

Personal imports are tested according to date of first use. To claim exemption, a letter from the vehicle manufacturer must be produced at the time of test.

Modified engines must still meet the requirements.

An older engine fitted to a vehicle will be tested to the age of the engine (evidence needed). A newer engine fitted to an older car will be tested to the age of the car i.e whichever is the oldest.

Vehicles which are not passenger cars are tested to different emissions limits in most cases. A passenger car is constructed to carry passengers, has no more than 5 seats excluding the driver, does not exceed 2500kg gross weight and is not a goods vehicle i.e pick-up, van or truck.

It will be necessary for evidence of first used dates to be produced in some cases (personal number plates, 1987's for seat belts and 1992's/94's for emissions) i.e V5 reg document or VE103 for leased/hired vehicles. Some vehicles may have been stored for long periods before being distributed by manufacturers. In these cases, if the vehicle was manufactured at least 6 months before its date of first use then the date of manufacture is used for test requirements.

Engines must be thoroughly warmed up and the oil temperature tested prior to testing (80 degrees C for most "CAT" tests although some are as low as 40 and 80 degrees C for Diesels). It's permissable for the emissions test to be carried out as soon as the vehicle arrives (environmentally friendly too) as long as the rest of the test is carried out on the same day by the same tester.

Any obstructions at the tailpipe which prevent the test probe being inserted will result in failure.

From 1st August 2001 a simplified emissions check was introduced and this will be carried out on vehicles prior to doing a full "CAT" test. If the vehicle meets the requirements during this BETs (basic emission test) then it passes. There will be no need to measure the engine temperature using the analyser probe but the vehicle must be at normal running temperature. However, engine rpm will still be measured. If the vehicle fails the BET then the full "CAT" test is applied.

The BET standards are:

Fast idle 2500-3000rpm

CO no more than 0.3%

HC no more than 200 parts per million

Lambda between 0.97 and 1.03

Normal idle 450-1500rpm

CO no more than 0.5%

any one tried just fitting a universal back box with all stock exhaust? any gud?

any one tried just fitting a universal back box with all stock exhaust? any gud?

That is basically what the Blitz NUR S does, it is designed to replace the stock rear box and connect to the stock mid pipes. As you can see on the pic below, there are 2 pipes exiting the back box to connect to the 2 pipes on the mid pipe. So not as straight forward as just fitting a rear back box, although I suppose you could cut off the stock back box and weld on a replacement.

Depends what you are wanting, if it's just for looks and to make the car a little louder then no reason why it couldn't be done, don't expect any performance gains though.

Blitz NUR S

http://www.blitz-uk.co.uk/images/products/variantimages/hires/MT2080_L.jpg

Stock NA Exhaust

I have got it on my sup fitted along with aftermarket exhaust manifold and it sound! It's not a big modification but you will feel a difference.

I had a cat back 5Zigen system on my N/A and had to go back to stock when it failed. The difference was huge in my opinion! The car was alot free-er before.

I am running double de-cat on the stock system at the moment until i find a suitable aftermarket cat-back system, and the car still feels restricted due to the over-restrictive stock exhaust.

ive got a single pipe [longlife] and double decat and friendly MOT guy

Thanks Nic, just thought i will go for a back box atm just to make it a bit louder, but will need them two pipes sorting some how which connect at the back of backbox!

Dave r u near swansea some where? Just thought i have seen ur white supra some where!!! nice car tho

Sorry to pull up a old thread here...

But, I've had a Chris Wilson first decat fitted the the car for a few months now.

The car performs much better but it has made the exhaust quite raspy, on closer inspection I've noticed that my 'mid' section (section before the backbox has no boxes... On the pics above one has boxes and one doesn't... Is one a tt exhaust and one the n/a?

Also can I just fit a new mid section with the boxes to my system with no hassle?

As it's either do that or refit the first cat as it just doesn't sound as nice as I hoped!

Yes you can just fit a mid section with the twin boxes......however the blitz back box you have could be an NA or TT one.......if yours is the NA one it should be then you need to ensure the mid section you get is from an NA. A TT's mid section rear most pipes will be too large in diameter for your NA Blitz nur S. (NB if it turns out you have a TT blitz nur s then either mid section will work)

Sorry to pull up a old thread here...

But, I've had a Chris Wilson first decat fitted the the car for a few months now.

The car performs much better but it has made the exhaust quite raspy, on closer inspection I've noticed that my 'mid' section (section before the backbox has no boxes... On the pics above one has boxes and one doesn't... Is one a tt exhaust and one the n/a?

Also can I just fit a new mid section with the boxes to my system with no hassle?

As it's either do that or refit the first cat as it just doesn't sound as nice as I hoped!

Is the mid section of your exhaust stock, ie. splits into 2 pipes as shown on the pics earlier? Can you post photos of the exhaust so we can see what it is?

On 3/24/2010 at 4:09 AM, Nic said:

Stock exhaust - Mid section and rear back box

https://jza80.mkivsupra.net/imports/2010/03/599.jpg

 

Cats - 1st cat is the smallest nearest the engine on RHS of pic.

https://jza80.mkivsupra.net/imports/2006/09/47.jpg

 

From your description it sounds like you have the stock exhaust with a Blitz NUR S back box fitted. If you want to fit a new mid section I'd suggest selling the back box and buying a complete cat back exhaust (everything thing from the cats back).

 

Nearly all aftermarket cat back exhausts are a single pipe through to the back, there are a lot of different makes and models available.

The second photo, is the first cat for a N/A supra or for the GTE?