Discussion
just in the process of doing some exhaust mods like sleeving and decatting exhaust has been removed for sleeving i now want to know how you decatt i noticed a y peice on front of engine with 2 lamba sensors with a bin on the bottom and if its done without removing the manifolds from the engine trying to keep the costs down ive been told clive f does one, any advice and photos would be appreciated
Pre-cats live just after the 4-1 joint on each manifold.
Removing them made very little difference to the way my Chim performed, the only change in sound was a bit more under bonnet noise.
The third cat is the one that does the work and resides in the big dustbin forward of the two manifolds.
I removed this whole section (commonly known as the Y piece) and replaced it with a de-catted one from ACT.
The ACT Y piece is not only de-catted it is also shaped better.
After fitting it I could feel the difference, obviously the main cat was causing quite some restriction on my car.
Along with a noticeable increase in performance the ACT Y piece had the effect of massively improving the sound of the engine.
Not a huge increase in volume as such (I retained the standard rear box) but more a significant improvement in the quality of the sound.
It now sounds like a proper V8 should.
Clive Ford also offers a de-catted Y piece, some report this is easier to fit than the ACT one.
I can confirm the ACT Y piece does require you use a ratchet strap to pull the manifolds in sufficiently to meet up with the Y piece.
However this is no different to the factory catted Y piece, my guess is the people that make the ACT one took their measurements from a standard Y piece, whereas Clive did a better job and made it fit the car properly.
Either way it's not a big issue, I only went with the ACT one because it came up second hand at a good saving.
TBH I have been extremely happy with it.
In my opinion, although you don't need the pre-cats to pass the MoT emission test (mine passed with only the main cat no problem), removing them gives such negligible benefits I would focus your attentions and money on that big main cat.
I can see only one real disadvantage to fitting a de-catted Y piece and that's at MoT time.
Without that big main cat the car will surely fail the emission test.
You then have two options:
1) Find a friendly MoT tester that will put the pipe up something else to give you a pass (highly naughty)
2) Swap your original cat back in for the test then put your de-catted one back afterwards (hassle, but very doable)
Option 1 is getter harder, as I understand it the new MoT rules now state if a cat was originally fitted and the car is presented for test without one, it is reason alone for a fail irrespective of the results of an emission test.
Personally I wouldn't bother de-catting your original dustbin, it's the shape of the ACT & Clive ford Y pieces that is as important as removing the cat itself.
De-catting your original dustbin would also leave you without the option of swapping in a catted Y piece for the test.
In summary I advise leaving the pre-cats where they are and fitting either the ACT or Clive Ford Y piece.
As long as you are comfortable with the MoT issue (which is not insurmountable) there are only benefits to fitting a de-catted Y piece.
You know you want to
Removing them made very little difference to the way my Chim performed, the only change in sound was a bit more under bonnet noise.
The third cat is the one that does the work and resides in the big dustbin forward of the two manifolds.
I removed this whole section (commonly known as the Y piece) and replaced it with a de-catted one from ACT.
The ACT Y piece is not only de-catted it is also shaped better.
After fitting it I could feel the difference, obviously the main cat was causing quite some restriction on my car.
Along with a noticeable increase in performance the ACT Y piece had the effect of massively improving the sound of the engine.
Not a huge increase in volume as such (I retained the standard rear box) but more a significant improvement in the quality of the sound.
It now sounds like a proper V8 should.
Clive Ford also offers a de-catted Y piece, some report this is easier to fit than the ACT one.
I can confirm the ACT Y piece does require you use a ratchet strap to pull the manifolds in sufficiently to meet up with the Y piece.
However this is no different to the factory catted Y piece, my guess is the people that make the ACT one took their measurements from a standard Y piece, whereas Clive did a better job and made it fit the car properly.
Either way it's not a big issue, I only went with the ACT one because it came up second hand at a good saving.
TBH I have been extremely happy with it.
In my opinion, although you don't need the pre-cats to pass the MoT emission test (mine passed with only the main cat no problem), removing them gives such negligible benefits I would focus your attentions and money on that big main cat.
I can see only one real disadvantage to fitting a de-catted Y piece and that's at MoT time.
Without that big main cat the car will surely fail the emission test.
You then have two options:
1) Find a friendly MoT tester that will put the pipe up something else to give you a pass (highly naughty)
2) Swap your original cat back in for the test then put your de-catted one back afterwards (hassle, but very doable)
Option 1 is getter harder, as I understand it the new MoT rules now state if a cat was originally fitted and the car is presented for test without one, it is reason alone for a fail irrespective of the results of an emission test.
Personally I wouldn't bother de-catting your original dustbin, it's the shape of the ACT & Clive ford Y pieces that is as important as removing the cat itself.
De-catting your original dustbin would also leave you without the option of swapping in a catted Y piece for the test.
In summary I advise leaving the pre-cats where they are and fitting either the ACT or Clive Ford Y piece.
As long as you are comfortable with the MoT issue (which is not insurmountable) there are only benefits to fitting a de-catted Y piece.
You know you want to
Don't de-cat the original dustbin, IMHO the sound is bloody awful, more tractor than V8 sportscar. If you decide to fully de-cat then spend some money and buy something like the ACT Y-piece, it's much smaller as obviously theres no dustbin left over that used to house a CAT and as such is sounds decent.
Zippee said:
Don't de-cat the original dustbin, IMHO the sound is bloody awful, more tractor than V8 sportscar. If you decide to fully de-cat then spend some money and buy something like the ACT Y-piece, it's much smaller as obviously theres no dustbin left over that used to house a CAT and as such is sounds decent.
When I removed my cat in the bin, it gave a 20ish bhp gain!thanks very much for your advice so far but just looked at the price of the replacement y piece from act and cant jusify spending £724 plus vat(£868) i could by my missus a cheap runnaround for that sort of money where do these people get there prices from unless there a lot cheaper way or something second hand i will stay with the standard set up by the way what sort of job is it to do should something cheap come along is it just a case of undoing those brackets and replacing with something else and where do the 2 lamba sensors go
Edited by v8kev on Wednesday 21st March 12:46
v8kev said:
thanks very much for your advice so far but just looked at the price of the replacement y piece from act and cant jusify spending £724 plus vat(£868) i could by my missus a cheap runnaround for that sort of money where do these people get there prices from unless there a lot cheaper way or something second hand i will stay with the standard set up by the way what sort of job is it to do should something cheap come along is it just a case of undoing those brackets and replacing with something else and where do the 2 lamba sensors go
There are often original Y pieces up on Ebay for £100.00 or so.Edited by v8kev on Wednesday 21st March 12:46
http://www.ebay.co.uk/itm/tvr-chimaera-exhaust-y-p...
Offer him £100.00 and see what he says, it's been up for ages with no takers.
Just cut the complete cat section out of an original & make up a tapered connection pipe where the cylindrical dustbin was.
You can use the car itself as a jig by connecting the upper half to the manifolds and the lower half to the down pipe.
Tack your new tapered middle section in place and finish the forming & seam welds off the car, when it goes back on it it will fit perfectly at both ends.
It's a bit of fab, but will save you hundreds.
You are looking to go from this:
To something more like the middle section of this:
haircutmike said:
Zippee said:
Don't de-cat the original dustbin, IMHO the sound is bloody awful, more tractor than V8 sportscar. If you decide to fully de-cat then spend some money and buy something like the ACT Y-piece, it's much smaller as obviously theres no dustbin left over that used to house a CAT and as such is sounds decent.
When I removed my cat in the bin, it gave a 20ish bhp gain!My ACT pipe felt like it gave my humble 4 litre another 10 - 15 ponies.
Without the cat it idles better, revs better and of cause sounds so much better too.
I paid £280.00 for mine, and worth every single penny.
The last one sold on E-Bay went for £300.00, so I think you can say thats the going rate for a used ACT Y piece.
http://www.ebay.co.uk/itm/TVR-Chimaera-Griffith-50...
Remove that big cat one way or another, you wont regret it.
By the way, you are well out with your prices, the ACT Y piece is actually £313.00 plus VAT.
Because of the value you get free postage too.
So that's £375.60 all in & delivered to your door.
Look again....
http://www.actproducts.co.uk/shop/ms04-griffith-50...
Edited by ChimpanLucky on Wednesday 21st March 13:45
i am right in asuming the lambda sensors still sit on the top also is it possible to use my existing y piece to convert rather than spend £100 on that one as it looks the same as mine it appears all i need is a man that can weld especially on exhausts or am i barking up the wrong tree
Edited by v8kev on Wednesday 21st March 13:52
v8kev said:
i am right in asuming the lamber sensors still sit on the top also is it possible to use my existing y piece to convert rather than spend £100 on that one as it looks the same as mine it appears all i need is a man that can weld especially on exhausts or am i barking up the wrong tree
The Lambda sensors sit in the manifolds not the Y piece so don't worry about that aspect, you are doing nothing with the manifolds.I still think the £375.60 ACT are charging is a good deal for the power gains & other benefits.
Remember if you remove the cat from your existing Y piece you could end up in a difficult situation come MoT time.
Much better to always have a catted Y piece as a spare, you then have the option of putting it back to catted if needed.
If £100 is still too much for you the quite honestly I would leave it standard.
Use the money to fill up your tank and go for a drive.
v8kev said:
are you saying the one on ebay at £175 is already decatted/converted, by the way i can afford £100 but i,m particular what i spendit on
The £175 one on EBay may or may not be de-catted already, you would really need to ask the vendor about that.To me it looks like the cat still resides, but you would need to confirm this with the man who owns it, there is nothing in the description to suggest it's been removed.
It's not a big issue to remove it, but unless you create a taper between the upper Y and the lower down pipe you are not getting the full benefit.
Mind you HCM seems to suggest he just removed his cat for the big empty dustbin effect, and still got 20hp in doing so.
Plenty of options and info above for you to make your decision.
I hope you've found it helpful?
Like I've said a few times now, getting shot of the cat (however you choose to do it) is well worth it.
Good luck and let us all know how you get on.
Kind regards, Dave.
ChimpanLucky said:
haircutmike said:
Zippee said:
Don't de-cat the original dustbin, IMHO the sound is bloody awful, more tractor than V8 sportscar. If you decide to fully de-cat then spend some money and buy something like the ACT Y-piece, it's much smaller as obviously theres no dustbin left over that used to house a CAT and as such is sounds decent.
When I removed my cat in the bin, it gave a 20ish bhp gain!My ACT pipe felt like it gave my humble 4 litre another 10 - 15 ponies.
Without the cat it idles better, revs better and of cause sounds so much better too.
I paid £280.00 for mine, and worth every single penny.
The last one sold on E-Bay went for £300.00, so I think you can say thats the going rate for a used ACT Y piece.
http://www.ebay.co.uk/itm/TVR-Chimaera-Griffith-50...
Remove that big cat one way or another, you wont regret it.
By the way, you are well out with your prices, the ACT Y piece is actually £313.00 plus VAT.
Because of the value you get free postage too.
So that's £375.60 all in & delivered to your door.
Look again....
http://www.actproducts.co.uk/shop/ms04-griffith-50...
Edited by ChimpanLucky on Wednesday 21st March 13:45
Chimpman - you went for the ACT replacement which if you read my initial post is what I recommended to do, you get the benefits of de-catting along with a much better sound.
TVR Beaver said:
if you do yours will it still pass the MOT?.. there are new rules coming also about CAT's removed and exhausts being messed with...
I'd buy another and do it that way... at least you've got the orig one to bolt back on if it becomes an issue??....
I've said that twice now, not sure he's listening I'd buy another and do it that way... at least you've got the orig one to bolt back on if it becomes an issue??....
One last time...
"Make sure you have a spare Y piece with the cat still in it so you can slip it on for the MoT test if need be"
If not & you de-cat your existing Y piece you will fail the MoT.
So your next post will likely be:
"Can anyone lend me a catted Y piece so I can pass my MoT"
The advice is here, but you do have to listen.
Good luck, we are all here to help each other
TVR Beaver said:
well i think that is more than clear now 
I know some will scrape past the MOT with no CAT's but most won't.....
All depends it you want to be bolting it in and out once a year....
You could fit a door on the dustbin thing and just remove the CAT??... Didn't someone do that??....
Like this?I know some will scrape past the MOT with no CAT's but most won't.....
All depends it you want to be bolting it in and out once a year....
You could fit a door on the dustbin thing and just remove the CAT??
... Didn't someone do that??....
Gassing Station | Chimaera | Top of Page | What's New | My Stuff