decatting

[verminator]

going to have the cerb serviced soon, and just wondered if it was worth asking them to take the cats off. they are the originals on a standard system. will it make any difference or can you only make the small gain if you fit a sports exhaust?

[BCA]

What is the spec of your Cerb??

I reckon the cats are a reasonably big restriction for the remapped/inductioned cars out there - though as far as I know, we're the only ones who still run cats whilst being in this state of tune?

[Peasantplucker]

The only difference you'll notice is a better rasp and a few more pops and bangs, but it makes me smile i don't think a few more (disputed) horses will be noticeable unless coupled with a remap etc.

[alinton]

Au contraire - When I decatted my previous Cerb, even without a remap the power increase was very noticeable.

Don't forget the ECU is adaptive, so will adapt itself to the increased flow.

Andy.

[thegreengoblet]

alinton said:

Au contraire - When I decatted my previous Cerb, even without a remap the power increase was very noticeable.

Same here - although I'd replace "very noticeable" with "unbelievable difference" in my case.

[Peasantplucker]

thegreengoblet said:

alinton said:

Au contraire - When I decatted my previous Cerb, even without a remap the power increase was very noticeable.

Same here - although I'd replace "very noticeable" with "unbelievable difference" in my case.

You're telling me you can notice a handfful of ponies amongst 360 odd!! Think you're being fooled by the extra noise!!

[BCA]

Peasantplucker said:

thegreengoblet said:

alinton said:

Au contraire - When I decatted my previous Cerb, even without a remap the power increase was very noticeable.

Same here - although I'd replace "very noticeable" with "unbelievable difference" in my case.

You're telling me you can notice a handfful of ponies amongst 360 odd!! Think you're being fooled by the extra noise!!

I've known of a blocked cats causing a car to be over 100bhp down in the past (now decatted, mapped and a healthy 391bhp I believe...)

I reckon they are a restriction on the more tuned cars out there, ours certainly makes very average power considering the mods its had done - I think if it was decatted it'd be alot more powerful, especially with a better exhaust. We'll have to wait and see about that though, other areas of the car need development first before we chase more power.

[thegreengoblet]

BCA said:

Peasantplucker said:

thegreengoblet said:

alinton said:

Au contraire - When I decatted my previous Cerb, even without a remap the power increase was very noticeable.

Same here - although I'd replace "very noticeable" with "unbelievable difference" in my case.

You're telling me you can notice a handfful of ponies amongst 360 odd!! Think you're being fooled by the extra noise!!

I've known of a blocked cats causing a car to be over 100bhp down in the past (now decatted, mapped and a healthy 391bhp I believe...)

I reckon they are a restriction on the more tuned cars out there, ours certainly makes very average power considering the mods its had done - I think if it was decatted it'd be alot more powerful, especially with a better exhaust. We'll have to wait and see about that though, other areas of the car need development first before we chase more power.

Nail. Head.

My Cats had been rattling around for quite some time and upon removal one was indeed blocked. She always felt quick even with the knocking cats. She was just a bit hesitant high up in the revs when you dumped your right foot. But I guess I wouldn't really of noticed the gradual decline in performance. Having said that, she's now an animal. Defo increase in power over the old performance before the cats ever began to knock. A lot more aggressive and twitchy too with wide throttle movements. She was always progressive with the power delivery albeit a little lumpy down in the revs. Now it's just full on and the noise increase adds to the drama!

However she maybe a little too loud now - I have sports pipes. Reckon I'll upgrade to an SP rear box next year, along with a remap and maybe, maybe a short induction kit (I'm still not totally convinced that the induction is worth the cost. I reckon she'd be well up in the 300's just with a remap).

[volospian]

thegreengoblet said:

...in the 300's...

lol, I hope so, after all that work

[Peasantplucker]

BCA said:

Peasantplucker said:

thegreengoblet said:

alinton said:

Au contraire - When I decatted my previous Cerb, even without a remap the power increase was very noticeable.

Same here - although I'd replace "very noticeable" with "unbelievable difference" in my case.

You're telling me you can notice a handfful of ponies amongst 360 odd!! Think you're being fooled by the extra noise!!

I've known of a blocked cats causing a car to be over 100bhp down in the past (now decatted, mapped and a healthy 391bhp I believe...)

I reckon they are a restriction on the more tuned cars out there, ours certainly makes very average power considering the mods its had done - I think if it was decatted it'd be alot more powerful, especially with a better exhaust. We'll have to wait and see about that though, other areas of the car need development first before we chase more power.

Obviously if there's a serious blockage in the cats then that will stifle the engine My 4.5 went on rollers with cats fitted and made 366bhp. My cats stay locked away in a box now and i'm hopefully booked into TCS sometime next month for a remap, but i'll bet a pound to a penny my engine will be within 10bhp of that pre-remap!! I also refer back to the OP who makes no reference to his car being remapped, so there

[thegreengoblet]

Peasantplucker said:

Obviously if there's a serious blockage in the cats then that will stifle the engine My 4.5 went on rollers with cats fitted and made 366bhp. My cats stay locked away in a box now and i'm hopefully booked into TCS sometime next month for a remap, but i'll bet a pound to a penny my engine will be within 10bhp of that pre-remap!! I also refer back to the OP who makes no reference to his car being remapped, so there

So 366bhp... is that from a standard untouched car i.e. never mapped, standard induction, standard exhaust?

[Peasantplucker]

thegreengoblet said:

Peasantplucker said:

Obviously if there's a serious blockage in the cats then that will stifle the engine My 4.5 went on rollers with cats fitted and made 366bhp. My cats stay locked away in a box now and i'm hopefully booked into TCS sometime next month for a remap, but i'll bet a pound to a penny my engine will be within 10bhp of that pre-remap!! I also refer back to the OP who makes no reference to his car being remapped, so there

So 366bhp... is that from a standard untouched car i.e. never mapped, standard induction, standard exhaust?

Yes, the only change from when the car left the factory is the removal of the cats. 366bhp is fairly typical for a standard 4.5, which also displayed the classic 'camel' hump which a remap should address. Peak torque was around the 320ft/lbs mark.

[BCA]

Peasantplucker said:

My 4.5 went on rollers with cats fitted and made 366bhp. My cats stay locked away in a box now and i'm hopefully booked into TCS sometime next month for a remap, but i'll bet a pound to a penny my engine will be within 10bhp of that pre-remap!!

You're probably right - but I dont reckon you'd be anywhere near the end figure once trackcar is done if you left your cats in - thier limit of flow must be around 380bhp I reckon... Just like the standard intakes limit appears to be (when decatted) around 390bhp. If you see what I mean?

[trackcar]

BCA said:

Peasantplucker said:

My 4.5 went on rollers with cats fitted and made 366bhp. My cats stay locked away in a box now and i'm hopefully booked into TCS sometime next month for a remap, but i'll bet a pound to a penny my engine will be within 10bhp of that pre-remap!!

You're probably right - but I dont reckon you'd be anywhere near the end figure once trackcar is done if you left your cats in - thier limit of flow must be around 380bhp I reckon... Just like the standard intakes limit appears to be (when decatted) around 390bhp. If you see what I mean?

If it makes 366 on my dyno pre map it's one of the very best .. most are 30hp shy of that as std ..

[Peasantplucker]

trackcar said:

BCA said:

Peasantplucker said:

My 4.5 went on rollers with cats fitted and made 366bhp. My cats stay locked away in a box now and i'm hopefully booked into TCS sometime next month for a remap, but i'll bet a pound to a penny my engine will be within 10bhp of that pre-remap!!

You're probably right - but I dont reckon you'd be anywhere near the end figure once trackcar is done if you left your cats in - thier limit of flow must be around 380bhp I reckon... Just like the standard intakes limit appears to be (when decatted) around 390bhp. If you see what I mean?

If it makes 366 on my dyno pre map it's one of the very best .. most are 30hp shy of that as std ..

Ooops, i wrote that from memory when at work, it actually made 360bhp, sorry about that folks, but it was on your dyno

[thegreengoblet]

[quote=trackcarIf it makes 366 on my dyno pre map it's one of the very best .. most are 30hp shy of that as std ..
[/quote]

So how much variation is there between different dyno's and runs on the same dyno? Obviously a before and after on the same dyno is a reasonably accurate measure of the difference gained or lost, or can even this be manipulated?

[BCA]

Peasantplucker said:

trackcar said:

BCA said:

Peasantplucker said:

My 4.5 went on rollers with cats fitted and made 366bhp. My cats stay locked away in a box now and i'm hopefully booked into TCS sometime next month for a remap, but i'll bet a pound to a penny my engine will be within 10bhp of that pre-remap!!

You're probably right - but I dont reckon you'd be anywhere near the end figure once trackcar is done if you left your cats in - thier limit of flow must be around 380bhp I reckon... Just like the standard intakes limit appears to be (when decatted) around 390bhp. If you see what I mean?

If it makes 366 on my dyno pre map it's one of the very best .. most are 30hp shy of that as std ..

Ooops, i wrote that from memory when at work, it actually made 360bhp, sorry about that folks, but it was on your dyno

Its still a very strong performance either way.. however my points are that if you had your car mapped and it made say 390-400bhp without cats - I reckon there would be more than 10bhp loss if you put the cats in and did a comparison... its what I believe is currently holding our car back from the 400club.

As I said before though, we're going to have to throw money at the car in other areas first before we chase more power and as we've proven post-Trackcar fettling, this absolute monster can still scare the hell out of the latest and greatest supercars out there. Its just nice to know theres still further potential without going mad...

[verminator]

thanks guys, very interesting. guess whats going in the bin at service time? well maybee the back of the gararge.