Discussion
caduceus said:
As a new Chimaera owner, I feel obliged to partake in the customary practice of decatting 
As I understand, there are pre cats and main cats. Pre cats in the manifolds? Main one in that metal dustbin in front of the rad?
As far as MOT issues go, does only taking out the pre cats out mean it will still pass emissions?
I don't want it too loud, like a tug boat. Just a deeper growl/burble.
Replies with pics are welcome
Cheers
Cad
I am also very interested in this as a new owner - would also quite like to remove the pre cats at least as I've read about the heat reduction benefits under bonnet.As I understand, there are pre cats and main cats. Pre cats in the manifolds? Main one in that metal dustbin in front of the rad?
As far as MOT issues go, does only taking out the pre cats out mean it will still pass emissions?
I don't want it too loud, like a tug boat. Just a deeper growl/burble.
Replies with pics are welcome
Cheers
Cad
hi, mine used to pass the mot with just the main cat still in place, ive got a feeling the precats were just for keeping emissions down on cold start up? if you kept the standard exhaust & fitted an act/clive f y piece its still a nice noise without being too loud. im sure others will be along shortly with their own favourite set up, mines fully decatted with an act cherrybomb exhaust & sometimes its a bit much tbh.
Edited by loud430 on Wednesday 2nd April 17:26
As above, pre-cats for cold start only and are not required for MOT, but main cat will be needed. Some people remove all the cats and just replace the main cat at MOT time, but not sure if insurance company would be very obliging if a claim is made.
Manifolds are a pig to get off, you need several different tools to remove them due to clearance issues.
Under bonnet temperatures are reduced by taking out pre-cats which is what I need to do on mine when I find the time and/or money to buy some nice ACT ones
Manifolds are a pig to get off, you need several different tools to remove them due to clearance issues.
Under bonnet temperatures are reduced by taking out pre-cats which is what I need to do on mine when I find the time and/or money to buy some nice ACT ones
My 450 has pre cats out and an ACT Y piece which is also decatted.
I have the standard Y piece for MOT time and all the mods are fully declared with insurers.
Taking out the cats lowers under bonnet temps, let's the engine rev quicker, make more power (some claim upto 25hp for all out), be more economical and sound better.
What are you waiting for?
PS - if you're near Gloucestershire, come and have a listen. I always think the You Tube clips are never true to life.
I have the standard Y piece for MOT time and all the mods are fully declared with insurers.
Taking out the cats lowers under bonnet temps, let's the engine rev quicker, make more power (some claim upto 25hp for all out), be more economical and sound better.
What are you waiting for?
PS - if you're near Gloucestershire, come and have a listen. I always think the You Tube clips are never true to life.
+1 for full decat with Clive F Y piece. Precats can be removed in situ, without removing exhaust manifolds bt it is a b#####d job to do. If you have a really clean running engine it can still just pass MOT emissions test with all cats removed, or find a recommended testing station / tester.
Richard 858 said:
+1 for full decat with Clive F Y piece. Precats can be removed in situ, without removing exhaust manifolds bt it is a b#####d job to do. If you have a really clean running engine it can still just pass MOT emissions test with all cats removed, or find a recommended testing station / tester.
Never in a month of sundays will an RV8 pass through a Cat test with no cat fitted 
if it did then I suggest that the testing stations gas analyzer is either faulty or is in need of calibration or both 
just a heads up 
Richard 858 said:
+1 for full decat with Clive F Y piece. Precats can be removed in situ, without removing exhaust manifolds bt it is a b#####d job to do. If you have a really clean running engine it can still just pass MOT emissions test with all cats removed, or find a recommended testing station / tester.
how does that work then, removing the precats with the manifolds in place? can anybody explain the process?mattgtd said:
Richard 858 said:
+1 for full decat with Clive F Y piece. Precats can be removed in situ, without removing exhaust manifolds bt it is a b#####d job to do. If you have a really clean running engine it can still just pass MOT emissions test with all cats removed, or find a recommended testing station / tester.
how does that work then, removing the precats with the manifolds in place? can anybody explain the process?This is how i did it:
1. REMOVE the Lambda sensors! 17mm deep socket with a grove kindly from the angle grinder biggrin
2. Electric drill with a large masonary drill bit...drill around the outside ensuring you go straight through
3. Then using a chisel I cut quarters out.....eventually they work loose and just pull out... trust me thumbup
4. When they are out...RUN UP YOUR ENGINE! It will sound like a Merlin Spitfire engine but you MUST blast the debris out...make sure you cover the wings with a suitable cloth; I was amazed how much came out...
My engine seems so much more responsive since these were removed...well worth the effort IMHO!
- copied from JenkoTVR after a quick google. Google, you should try it sometime.
Sardonicus said:
ever in a month of sundays will an RV8 pass through a Cat test with no cat fitted if it did then I suggest that the testing stations gas analyzer is either faulty or is in need of calibration or both just a heads up
^^^^This^^^^ if it did then I suggest that the testing stations gas analyzer is either faulty or is in need of calibration or both just a heads up Most MoT testers these days have never seen the sort of figures an RV8 shoves out.
My young tester krraped himself when he saw my fully de-catted Chim on petrol at 13:1 AFR on idle, way better when I flick her to gas but to be honest even sniffing propane she's still not winning any environmental awards
But I the truth is what comes out the back of even the heaviest polluter pales into insignificance when you compare it with the environmental impact of building a car in the first place.
As such the longer you keep a car the greener it becomes... even if it is an horrific stinker like ours.
Your TVR is greener than you think
OleVix said:
mattgtd said:
Richard 858 said:
+1 for full decat with Clive F Y piece. Precats can be removed in situ, without removing exhaust manifolds bt it is a b#####d job to do. If you have a really clean running engine it can still just pass MOT emissions test with all cats removed, or find a recommended testing station / tester.
how does that work then, removing the precats with the manifolds in place? can anybody explain the process?This is how i did it:
1. REMOVE the Lambda sensors! 17mm deep socket with a grove kindly from the angle grinder
2. Electric drill with a large masonary drill bit...drill around the outside ensuring you go straight through
3. Then using a chisel I cut quarters out.....eventually they work loose and just pull out... trust me
4. When they are out...RUN UP YOUR ENGINE! It will sound like a Merlin Spitfire engine but you MUST blast the debris out...make sure you cover the wings with a suitable cloth; I was amazed how much came out...
My engine seems so much more responsive since these were removed...well worth the effort IMHO!
- copied from JenkoTVR after a quick google. Google, you should try it sometime.
OleVix said:
I left my manifolds in situ...2hrs to do the first as I wasnt sure how to go about it...15mins for the second..
This is how i did it:
1. REMOVE the Lambda sensors! 17mm deep socket with a grove kindly from the angle grinder biggrin
2. Electric drill with a large masonary drill bit...drill around the outside ensuring you go straight through
3. Then using a chisel I cut quarters out.....eventually they work loose and just pull out... trust me thumbup
4. When they are out...RUN UP YOUR ENGINE! It will sound like a Merlin Spitfire engine but you MUST blast the debris out...make sure you cover the wings with a suitable cloth; I was amazed how much came out...
My engine seems so much more responsive since these were removed...well worth the effort IMHO!
This is how i did it:
1. REMOVE the Lambda sensors! 17mm deep socket with a grove kindly from the angle grinder biggrin
2. Electric drill with a large masonary drill bit...drill around the outside ensuring you go straight through
3. Then using a chisel I cut quarters out.....eventually they work loose and just pull out... trust me thumbup
4. When they are out...RUN UP YOUR ENGINE! It will sound like a Merlin Spitfire engine but you MUST blast the debris out...make sure you cover the wings with a suitable cloth; I was amazed how much came out...
My engine seems so much more responsive since these were removed...well worth the effort IMHO!
- copied from JenkoTVR after a quick google. Google, you should try it sometime.
- *FACEMASK***
- *VENTILATION***
caduceus said:
Replies with pics are welcome
Cheers
Cad
I really hate posting pictures of beastie Cheers
Cad
but seeing as no one else has posted a picture I guess it's down to me. Yes yes I know it's really good of me to take the time to do it, but if pictures of beastie help others, then who am I to deny them Full decat, Clive F 'Y', box put back to standard (was previously sleeved), sounds awesome
Well in my humble opinion anyway Shiny 'Y' just visible
ChilliWhizz said:
I really hate posting pictures of beastie but seeing as no one else has posted a picture I guess it's down to me. Yes yes I know it's really good of me to take the time to do it, but if pictures of beastie help others, then who am I to deny them
Full decat, Clive F 'Y', box put back to standard (was previously sleeved), sounds awesome Well in my humble opinion anyway
Shiny 'Y' just visible
NICE ! but seeing as no one else has posted a picture I guess it's down to me. Yes yes I know it's really good of me to take the time to do it, but if pictures of beastie help others, then who am I to deny them Full decat, Clive F 'Y', box put back to standard (was previously sleeved), sounds awesome
Well in my humble opinion anyway Shiny 'Y' just visible
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