Cool decat

[Petrus]

Have the decat midpipe and motorbike no-muffler fitted.
For one I thínk it revs easier, secondly it is noticably lighter, thirdly it is more than noticably LOUDER and fourthly (is that a word?) it is cóól. I mean líterally cool, as in lower temperature.
Way beyond expectation cooler.

Mountain girl has the day off so we went for a spin. Looked very iffy with dárk skies all around us but hey, if you have it; fold it down.
First a tank/coffe stop; Belle some 98 superfuel and a bottle of fuel system cleaner, Mountain girl a colacao, me a coffee.
Back on the road the sky broke and on the south slope all sunny, warming up nicely to short sleeved driving.

We did just over 200 km. of which 180 over comarcales; C-roads. Just one up from dirt roads.
At the beach popped the rear lid open and ... no hot wave. None at all! So put a hand above the black heat shield and ... nothing, so laid my palm on it; not even luke warm!!
Ok, but that is dówn the mountain.

Back up the mountain I did not flog it but did push it enough to slide the Yokos on the nicely warmed up tarmac.
Near home some over the highway up the Pedrizas pass; 6 km. of 8% at 160 km/h.
The next and last 10 kms over B-road I did flog it.
At the farm popped the lid open and... Same thing. Sóme warm air rising but not warranting the tag ´heat´. The heat shield was warmer too, but could still press my palm on it comfortably.

Oh, I also left the nappy off. That will no doubt make a difference too but the biggy is the catalist.

Again, I had not expected it to run thís much cooler.

[jvanzyl]

If you wrap it all up in heat wrap it gets even better :-)

But totally agree that it revs easier. Does yours throw the p240 code occasionally as well?

[Petrus]

If you wrap it all up in heat wrap it gets even better :-)

Could be but:

- wrapping the header may stress the limits of the quality of the header I have. I thus have the OEM shields fitted.
- wrapping the midpipe would see it rust a lot more, imo looks bad from behind and ... see below
- wrapping the muffler would stress the rivets (it´s repackable)

But totally agree that it revs easier.

Don´t know if there are any dyno charts about it, but it should equal hp increase.

Does yours throw the p240 code occasionally as well?

It did.
With the sensor extension is sofar has not.
Wrapping the midpipe would increase that tendency.

[jvanzyl]

I need to look up on that sensor extension then...
I have a lightened flywheel as well and I find the decat reduces the amount of revs needed to pull away.

[Petrus]

I need to look up on that sensor extension then...
I have a lightened flywheel as well and I find the decat reduces the amount of revs needed to pull away.

Makes sense as the scaveging is better, i.e. less tendency to stall at low revs.
I find that the engine accepts more throttle at lower revs, which is basically the same thing.
If you realise that the cat has a muffling effect because of surface ´friction´ as the gas needs to pass over a large as possible surface of catalyst it makes sense that without it the scaveging improves.

It also effectively stops cat theft ;-)

[thetyrant]

I was amazed how much hotter it was in engine bay when I refitted nappy recently!  I wont be putting it back now its off for turbo install that's for sure, also will look to open up the fake venting around the numberplat area to let some heat out.

[Petrus]

also will look to open up the fake venting around the numberplat area to let some heat out.

Thought about that. Does it pop out easily?
Am a bit loath about removing any of the pop in plastics as the tabs have not become more flexible over time.

[Nvy]

also will look to open up the fake venting around the numberplat area to let some heat out.

Thought about that. Does it pop out easily?
Am a bit loath about removing any of the pop in plastics as the tabs have not become more flexible over time.

I dont think that the area is that huge behind the number plate because of the crash bar or w/e is called. If we go tubular and then replace the plastic with mesh it would be a great upgrade.

[Petrus]

I dont think that the area is that huge behind the number plate because of the crash bar or w/e is called. If we go tubular and then replace the plastic with mesh it would be a great upgrade.

Good point.

[thetyrant]

I dont think that the area is that huge behind the number plate because of the crash bar or w/e is called. If we go tubular and then replace the plastic with mesh it would be a great upgrade.

Its not huge area no and as you say crash bar is behind but any extra air flow is a bonus, i guess optimum for cooling flow at least would be open out the whole rear area with mesh and relocate the number plate with a stick on version above on bumper, might look a bit poor though will think about that in future

[cptspaulding]

Mountain girl a colacao, me a coffee.

Mmmm. Colacao y churruscos. El desayuno de campiones!

[Petrus]

Mountain girl a colacao, me a coffee.

Mmmm. Colacao y churruscos. El desayuno de campiones!

Lo sé, pero para mi es tostado con tomate y aceite.
Toast with freshly grated tomato and olive oil.
First the oil on the toast so the tomato pulp does not soak into the toast, than a sprinkling of coarse salt hmmmmmmm.... With cappucino ofcourse; all for 2 € 50 on a terrace in the sun.

A photo of the pre MoT decat install.
Currently without the plastic tray.
See why I prefer it unwrapped ;-)




The cross flow non-muffler exits on the rhs so tha leaves the lhs hanger free to hook something fun up. I´ll think of something typically JDM yet ;-)
If the HelloKitty tip would be cheaper I´d go for that too :-)

[Joesson]

@Petrus, It would cost £2.50 for a cappuccino only in the UK where currently you can sit inside looking at the gently falling rain!

[Petrus]

@Petrus, It would cost £2.50 for a cappuccino only in the UK where currently you can sit inside looking at the gently falling rain!

Seen the road trip we did yesterday?
Stopped at a Venta (roadside restaurant) for a drink and a bite. Mineral water, a cola and two rather large tapas; 4€.
At the coast, in a fashionable restaurant ón the beach, live music in front, lunch for 2 was 24€ and we think that ´expensive´.
Mountain girl said she´d pick me up for lunch in the village today. Our son may drop in too. Will be something like 18€ for the three. A ´plato combinado´, say fish&chips is 2.50.

Oh and the empty roads; don´t forget the well maintained, empty roads snaking through wonderful views under the sun.

It réally is affordable driver´s paradise; a great idea for a spring break. Outside of the summer season there is no need to book hotels or what. Just drive into the mountains, lunch where you fancy a stop, ask for lodgings late in the afternoon, have diner (late!) a the local restaurant at town square around the corner.

[Petrus]

Lunch was 13.80    for the three   

Just collected the cat, muffler and nappy; by jóve that is heavy. Rather satisfactory too; having reduced the bulk of that weight.

[Petrus]

If you wrap it all up in heat wrap it gets even better :-)

I'm a noob at this, but what does wrapping up the no-cat manifold (like from Toyosports) achieve?

Wrapping = insulating, meaning the exhaust gas does not cool, goes faster = better scavenging. This only works though if the rest of the system flows at that speed otherwise the gas will simply back up and go as fast as it can pass the slowest part.

A secondary effect is that it reduces heat radiation from the wrapped bit.

The downside is higher thermal load on the part wrapped.

[Petrus]

Thanks for the answer! So if I understand this correctly it works only if you also have a decat midpipe and a non-stock silencer?

Or at léast a sports cat and indeed a better flowing muffler.

[Petrus]

From what I hear the car needs to be really warmed up to pass MOT with a sports-cat, right?

Íf it passes.
I am not risking it.

[Ardent]

Or at léast a sports cat and indeed a better flowing muffler.

Okay, thanks!

From what I hear the car needs to be really warmed up to pass MOT with a sports-cat, right?

I generally believe that too be good practice regardless. Certainly not detrimental.

[Ardent]

This had me thinking the other day, is the unsightly stainless steel cat heat shield there to keep the cat hot, or protect those from the hot cat, even though the heat shield will be hot itself?
Which leads on to would it be detrimental to remove the stainless steel cat heat shield and run without, purely for aesthetic reasons if nothing else.

[Carolyn]

This had me thinking the other day, is the unsightly stainless steel cat heat shield there to keep the cat hot, or protect those from the hot cat, even though the heat shield will be hot itself?
Which leads on to would it be detrimental to remove the stainless steel cat heat shield and run without, purely for aesthetic reasons if nothing else.

The heat shield (like a wrap) keeps more heat in the cat and protects the car.  I wrap after-market cats for that reason.  Personally, I quite like the OEM heatshields, they are well made from quality metal.

[Petrus]

Personally, I quite like the OEM heatshields, they are well made from quality metal.

Ditto.
That is why I retained them for the decat manifold.
Looks totally OEM as a bonus:

[Ardent]

I totally agree re the cat shield. Shame the fixings are not.
Still, easily remedied.

Thanks for answering the question.
Taking the wrap as a lead in.
As an alternative, is there merit in ceramic coatings. Or just more snake oil?
Again, looking at it primarily from an aesthetic perspective.

Edit
Just for clarity. I am only talking about the  cat the bit visible from the rear under the car and not the pre-cat manifold area.

[Carolyn]

I totally agree re the cat shield. Shame the fixings are not.
Still, easily remedied.

Thanks for answering the question.
Taking the wrap as a lead in.
As an alternative, is there merit in ceramic coatings. Or just more snake oil?
Again, looking at it primarily from an aesthetic perspective.

Edit
Just for clarity. I am only talking about the  cat the bit visible from the rear under the car and not the pre-cat manifold area.

There is merit in ceramic coating.  It can be surprisingly effective.  But would you spend say £200 on coating and after-market cat?  Being a tight-wad, I stick to wrap!

[Petrus]

and be dóne with it