Fitting a decat downpipe

[Petrus]

It's a funny old world. I try to do my bit where I can, generally, whilst also allowing myself a few vices.

Ok a quick but fairly accurate one on a new cat:

The welding contributes about 200 gram of CO2.
The steel 1.8 kilo of CO2 per kilo. This does not take into account the environmental cost of iron mining.
Platinum is ... horrific and quite a relief that there is only a minute quantity in the cat.

Aluminium btw, even considering 50 % recycling rate, has a footprint of 8,96 kg CO2 per kg. Glass is 25 times eco friendlier.

To put that in perspective; every gallon of gasoline burned gives about 8,887 grams of CO2.
So a thousand gallons results in 8.887 kilos of CO2.
Without a cat at 30 mpg that is 30.000 miles for 8.887 kilos.
15% weight reduction giving 5% improved fuel economy saves 0.444 kilo of CO2; the welding of two cats.

Right, now have a beer or what to unboggle the mind.

[househead]

I shall setup another weekly meet and you can have a go in my setup. There is a significant difference going full decat, with sound being one of the factors you should bear in mind.

Can you make it out to sort of towards Slough maybe South of that?

That would be sweet mate, thanks. Definitely can make it out that way. Just over an hour away, which is basically about how long it takes me to get to a decent road anyway

[Petrus]

As a cynic I would like to know how much effort is put into making a catalytic converter, do the companies that supply and make the cats actually pump out more No2, CO & hydrocarbons then these things save?  The precious metals in cats have to be dug out of the ground, processed and then shipped to a factory.  The factory will burn energy like no tomorrow putting together these pieces of kit and then transport them to a car manufacturer.

Short answer; yes.
See the values I gave above.

[househead]

Haha @Petrus already one step ahead on the beer! Thanks for the figures, they definitely had me heading for the fridge (again) too 

I love the theory of saving mass, but I love my speakers, sub and storage more! I might test her without power steering some time soon though. I actually run with the spare wheel in the frunk because I'm hesitant to drop weight in the front without balancing it in the back somehow. I think the toyosports is quite a bit lighter than the stock manifold but it's somewhat offset by the TTE dual exhaust which is by my reading "pretty. Damn. Heavy"

[Petrus]

Haha @Petrus already one step ahead on the beer! Thanks for the figures, they definitely had me heading for the fridge (again) too 

I love the theory of saving mass, but I love my speakers, sub and storage more! I might test her without power steering some time soon though. I actually run with the spare wheel in the frunk because I'm hesitant to drop weight in the front without balancing it in the back somehow. I think the toyosports is quite a bit lighter than the stock manifold but it's somewhat offset by the TTE dual exhaust which is by my reading "pretty. Damn. Heavy"

The mass reduction is only an example to show the relativity of the cleaner cat.

The rest of the numbers you can crucch to see that doing just a few months longer with a 10 y.o. car ´saves´ more carbon footprint than the gasoline over the average 1o year distance driven produced uncatted.
So although there is no discussion that less footprint is better, we are totally misinformed/manipulated about the whole picture.

Back to the weight distribution.
Have a look at the Spyder´s versus the Elise´s.
Don´t worry about chucking any weight anywhere with respect to the belance. Simple aero mods do a power of greater good ;-)
That written; a decat manifold, decat pipe and lighweight muffler easily save 20 kilos.

As observed by others, be aware that a decat midpipe is a lot louder.
Having swapped about the lot in mine I´d say that (starting from a decat header) the muffler is 2/3 of sound reduction and the cat 1/3.
A sports exhaust with decat midpipe will be LOUD.
The increase in noise bear noooo relation to the extra oompf.
You can easily go 18 or more dB = being 600% louder whereas you get at best 10% or so hp extra?

I am currently back to OEM and mán it´s silent. If anything I drive faster in silent mode because of the relative ´stealth´ so the extra oompf is useless; just attracts attention.

[Nvy]

About the noise, decat + OEM muffler is perfectly fine for daily driving. I wonder what would happen if I fit a cat at the moment. Id imagine that I wont be able to hear anything but wind noise. I have a heat wrap - the cheapo one - on the header and down pipe and no drone is present. With the previously fitted TTE, the exhaust was loud, like on 6k rpms it would scream so much that my head would start hurting in 10 mins or so.

[Petrus]

on 6k rpms it would scream so much that my head would start hurting in 10 mins or so.

10 minutes at 6000 rpm the engine´s head might start to hurt too ;-)

No, seriously, my decat header, decat midpipe and superbike no-muffler combi is seventies Kawa 900 open 4-1 level of noise.
The only thing coming close nowadays are ´kids´ on larger capacity quads with unbaffled pots.
Still not found an alternative :-(

[househead]

TBF The noise is a concern as I'm running the TTE exhaust and it's already pretty loud. It's a level of loudness I'm happy with but I don't think I'd want *much* more.

Am tempted by the Malian 200 cell sports cat. Comes as part of a downpipe so no fabrication and it's only £175. It would also allow me to keep the old pipe and cat intact so if there are MOT issues (notwithstanding a good, hard ragging before handing over for the test) it could always be swapped back.

[jvanzyl]

TBF The noise is a concern as I'm running the TTE exhaust and it's already pretty loud. It's a level of loudness I'm happy with but I don't think I'd want *much* more.

Am tempted by the Malian 200 cell sports cat. Comes as part of a downpipe so no fabrication and it's only £175. It would also allow me to keep the old pipe and cat intact so if there are MOT issues (notwithstanding a good, hard ragging before handing over for the test) it could always be swapped back.

One of the ideas I was working on was to take a decat pipe and cut out the section where the cat should be and have v-band flanges put on. This would enable swapping in and out of your desired cat level or no cat quickly and easily.
i.e. off to track day or off to the MOT etc..

[househead]

Nice idea that @jvanzyl did you get a price on having a pipe modified in this way?

[jvanzyl]

Nice idea that @jvanzyl did you get a price on having a pipe modified in this way?

Not yet... basically it's a max 2 hour job to swap over a cat pipe without the v-band idea... the current plan is to schedule in 4 hours a year for this work :-)

[Petrus]

Not yet... basically it's a max 2 hour job to swap over a cat pipe without the v-band idea... the current plan is to schedule in 4 hours a year for this work :-)

I found that with the car on the bridge I can quite easily get the cat and/or the muffler in out from underneath. Only need to take the nappy off.

As to the sound level househead you will hear it at jvanzyl but imo you will be unpleasantly surprised if you think the TTE is loud enough. The cat really muffles.

For mé a sports cat is not a route I go as maybe yes maybe no on the MoT emission means I would drop in the OEM cat anyway for MoT and I réally do not like the heat radiation of the cat.
The set up on our MR2 is enclosed ín the engine room, not like front engine cars in the cool air underfloor.
The heat behind the car at a road side restaurant is shocking:
With the OEM set up the lid gets pretty hot and the hot air really hits you. It also takes a lóng time for the rising air to get noticebly cooler.
The cat gets HÓT and the rising heat, heats up the hot muffler even more.
Whatever the muffler set up, deleting the cat will significantly lower the temp. because there will be 5 kilo less heatsink ánd the exhaust gasses have less time heating up the rear.

That observed I am at the moment a bit stumped as the decat & bike muffler combo I had is simply too loud and I´d rather fit the cat and bike pot than no cat and OEM muffler.

[househead]

Only need to take the nappy off

That's about 30mins (25%) of the job! I'm actually thinking of leaving mine off the next time it comes off. Which will probably be really soon if I'm going to commit to oil changes every 3k miles. Feels like I only just changed the oil, but a trip up to Scotland and back added some serious mileage!

[jvanzyl]

Yeah if I had car lift it would be nice and quick... but I don't unfortunately! Oh well..

My setup is fully heat wrapped from exhaust header till the exhaust muffler.
On a plus side, I got 39mpg as an average on the last tank, and that's with country laning and motorways and stop start etc... so I reckon there a slight economy to it.

But yeah noise can be dealt with my turning the music up louder as well..

[househead]

But yeah noise can be dealt with my turning the music up louder as well..

My neighbours are gonna LOVE me!

[Petrus]

But yeah noise can be dealt with my turning the music up louder as well..

I did a delete on the sound system as I mostly drive top down which very effectively drowns all sound quality so why bother?!

Opening up the exhaust indeed increases fuel economy. The say 10% power gain is the engine not using power in pushing the gasses out. Using the same engine power to drive it means less fuel burned to flush the gasses. It also means less CO2 produced.
There is a direct link to fuel burned and CO2 pumped out.

[Petrus]

Btw. the complete exhaust system; manifold w. cats, cat, muffler, shields, assorted hardware, weighs a whiff over 30 kilos.

Muffler is 12.5 kg.
Cat is 7.6 kg.

[MannyUK]

10 minutes at 6000 rpm the engine´s head might start to hurt too ;-)

Its my head/ears that hurts, it really does.  I used to drive a 500mile trip to work once a week and I used a noise cancelling headset designed for a helicopter to make it bearable.  On short fun trips no problem but the drone on a motorway for 6 hours is horrific.  Bear that in mind before you do it or maybe be a passenger in someone elses with a similar setup.

[Nvy]

10 minutes at 6000 rpm the engine´s head might start to hurt too ;-)

Its my head/ears that hurts, it really does.  I used to drive a 500mile trip to work once a week and I used a noise cancelling headset designed for a helicopter to make it bearable.  On short fun trips no problem but the drone on a motorway for 6 hours is horrific.  Bear that in mind before you do it or maybe be a passenger in someone elses with a similar setup.

I meant some spirited driving but not constantly being on 6k rpms We have speed limit, if we were in Germany that would be another story Now I have OEM muffler and im happy.

[Petrus]

I might test her without power steering some time soon though.

The ´00 tech info doc. on the new MR2 mentions that in case of failure the electric assitance is switched off and the steering functions as manual. Imo this means the power assist is designed to not hamper manual function.

I actually run with the spare wheel in the frunk because I'm hesitant to drop weight in the front without balancing it in the back somehow.

I´ve started a thread on that.

You will reduce understeer.
Mind; I have seriously lightened the front, upped tyre pressure a whiff, gone 195 and at lower speeds it will still understeer on sharp turn ins into tighter corners even on AD08Rs.

Stabilty at speed is an aero issue. Weight up front is only massaging the symptom.

Though not addressing the real cause either, deleting power steering has the side effect that the car appears more stable at speed because it respons less twitchy on driver input.

[househead]

That's good to know @Petrus understeer is indeed the work of the devil!

For me, removing the power steering will be more about improving the road feel, with the added benefit of losing some mass if I went the whole hog and ripped it physically out. Also need to check on the legality of that too. It's just an idea at this stage rather than something I'll definitely do.

[Petrus]

That's good to know @Petrus understeer is indeed the work of the devil!

For me, removing the power steering will be more about improving the road feel, with the added benefit of losing some mass if I went the whole hog and ripped it physically out. Also need to check on the legality of that too. It's just an idea at this stage rather than something I'll definitely do.

No need to: It is not allowed unless you have a declaration of the manufacturer and a certificate of the work from a registered garage.

Still more than is possible for a decat manifold a decat midpipe of a non homologated muffler. The létter of the rules do even not permit the so called ´cool air inlets´ replacing the OEM filter housing.

[McMr2]

That's good to know @Petrus understeer is indeed the work of the devil!

For me, removing the power steering will be more about improving the road feel, with the added benefit of losing some mass if I went the whole hog and ripped it physically out. Also need to check on the legality of that too. It's just an idea at this stage rather than something I'll definitely do.

No need to: It is not allowed unless you have a declaration of the manufacturer and a certificate of the work from a registered garage.

Still more than is possible for a decat manifold a decat midpipe of a non homologated muffler. The létter of the rules do even not permit the so called ´cool air inlets´ replacing the OEM filter housing.

Is the universal joint (joints) up to the task of running without assistance? Particularly considering that some may well have endured many years of use already.

[Petrus]

Is the universal joint (joints) up to the task of running without assistance? Particularly considering that some may well have endured many years of use already.

Dunno. If it has/develops play then replace it. Should be easy to check/replace if you have the vanity cover out.

Now I have easy talking as I hardly do any slow traffic nor parking manouvring and at the farm the parking is hardpack crushed gravel.