Broken Down

[CatmanV2]

Your car does not have cats in the manifolds, I'm sure

C

 

[Wack61]

good news , you should open a shop, with customer service this good you'd make a fortune

 

[boomerang]

Here you go, this is what Benny had made up for me, £400

This is the secondary cat delete and open up the squish pipes with twin pipes.

My primary's are in the manifolds, they were moved there to stop the issue you had, putting 2 cats in this pipe.

You basically need the same with a single cat in each and if you want to keep it quiet (which I am sure you don't) have a small cherry bomb free flow silencer where the secondary cat would have been.

The cats are about £100 each so your looking at circa £600

View attachment 36338

That looks very good, better then the Supersprint units i mounted a few years ago.
And for a very good price!

Some specialist state that the squish pipes have more than enough flow and that the twin pipes will not bring any advantages.
What do we think about those comments?

 

[Spartacus]

i know they are not in the manifold . they are just before the secondaries . I just need to know how many cell they are

Your car does not have cats in the manifolds, I'm sure

C

 

[Spartacus]

On another note i have just had a chat with Meridian Modena in Lyndhurst and asked them about cat break up while i was on the phone . They said that they can break up and in some cases causing engine misfires ect and need replacing ...... But they had NEVER had a Fooked engine due to one . Infact they said the 4200 engine is near enough bomb proof mechanically ( probably not the oil pump failure though ;P ) and they have only ever had to repair 1 engine and that was due to "customer stupidity" lol


Food for thought.

 

[dem maser]

That looks very good, better then the Supersprint units i mounted a few years ago.
And for a very good price!

Some specialist state that the squish pipes have more than enough flow and that the twin pipes will not bring any advantages.
What do we think about those comments?

Good to see you back on here Luuk

 

[CatmanV2]

That looks very good, better then the Supersprint units i mounted a few years ago.
And for a very good price!

Some specialist state that the squish pipes have more than enough flow and that the twin pipes will not bring any advantages.
What do we think about those comments?

I spoke to someone that does fluid dynamics for a living. And his answer was 'it depends' It's really not very clear cut. What *is* clear cut is that splitting the flow and then rejoining it is generally a bad thing. Whether it's better or worse than squishing it would take some testing.

C

 

[CatmanV2]

i know they are not in the manifold . they are just before the secondaries . I just need to know how many cell they are

I was aiming my observation at Wack
C

 

[drewf]

I spoke to someone that does fluid dynamics for a living. And his answer was 'it depends' It's really not very clear cut. What *is* clear cut is that splitting the flow and then rejoining it is generally a bad thing. Whether it's better or worse than squishing it would take some testing.

C

That squished pipe isn't made from flattened tubing of the same cross-sectional area as the round pipe. It's surprising how fast the gases can be made to flow in such a pipe - some mainstream manufacturers are using interestingly similar flattened curved sections on induction systems.

 

[Corranga]

Wow, just read this whole roller coaster of a thread. Seems like a decent result anyway. Cost aside, a replacement engine doesn't do much for resale / value either, or at least I'd imagine it doesn't given the way people talk about missed services on here

My little old Elise destroyed it's cat. I ended up with a ball of ceramic floating around in the cat casing, which, when hot, blocked the exhaust, which in turn cause more heat and obviously stopped the exhaust flowing. I noticed as the car was spitting tiny pieces of hard white stuff out the tail pipe!!

Anyway, as a potential buyer of a 4200 (or other Maser, if I ever get my finger out and reassemble my 944 and get shot of it..), I'm looking at the exhaust layout here:
http://www.eurospares.co.uk/parts/maserati/4200-coupe-2003/exhausts/exhaust-system-20475
What do you all mean by primary and secondary cats?
I only see a single cat (per side) indicated as 1 and 2 on the diagram.
Or is there 2 sections of cat, pre and post squash pipe, but in the same unit (so to speak).

As for exhausts sucking things in, I'm no expect, but I'd imagine as the cylinder descends on a cold engine during starting, there would be no fumes being blown out, so no resistance there, but it could suck / ingest the cat materials due to them being located so close to the engine? Granted, it would probably take quite a lot of it to do any damage, but if it's happening over time, and then the ingested hard stuff becomes grit in the oil..
I'd imagine there are other answers due to pressure, temperature, exhaust leaks, other stuff...

Chris

 

[CatmanV2]

Both in the same pipe. The lump at the front of parts 1 and 2 are the primaries with the Lambda sensors fore and aft. (6 and 9) The secondaries are the lumps at the back.

As for ingestion: Try putting a small ball of rolled up paper in the neck of a bottle on its side. Then blow the paper into the bottle. Fluid dynamics makes my brain hurt!

C

 

[Swedish Paul]

I notice that Larini have a 4 cat version and a 2 cat version. Opinions?

It's just that on the FD website,

Sports-Cats (2 - De-cats) $1895 - rear lamba sensor is moved because the cat is at the back
Sports-Cats (4 - Direct replacement) $3795 - same sensor placement as original

 

[boomerang]

Good to see you back on here Luuk

Hi Demitri, how are you?
You still are the proud owner of the AC 3200 i presume?
Never sell that car, its probably one of the best investments you ever did!

Yes, it has been quiet for a while due to circumstances, but the Gransport is on the road again and that helps.
Even did a small update regarding the Gransport; just look for "cam variator pre lube" at this forum.

Good to see the large quantity of relevant posts out here, still, great!

 

[dem maser]

Hi Demitri, how are you?
You still are the proud owner of the AC 3200 i presume?
Never sell that car, its probably one of the best investments you ever did!

Yes, it has been quiet for a while due to circumstances, but the Gransport is on the road again and that helps.
Even did a small update regarding the Gransport; just look for "cam variator pre lube" at this forum.

Good to see the large quantity of relevant posts out here, still, great!

Hi Luuk

No. Unfortunately not. I had to sell the AC to fund the house purchase we made....im now on my own without her so I desperately want my AC back....

Good to hear from you Luuk

 

[Corranga]

Both in the same pipe. The lump at the front of parts 1 and 2 are the primaries with the Lambda sensors fore and aft. (6 and 9) The secondaries are the lumps at the back.

As for ingestion: Try putting a small ball of rolled up paper in the neck of a bottle on its side. Then blow the paper into the bottle. Fluid dynamics makes my brain hurt!

C

Thanks, that makes sense, and of course with the sensors being prior to the secondaries, removing the secondaries makes no difference to the ECU.

I think I can visualise the bottle example working.
The air flowing in gets past the paper blockage (cat 1).
The air then hits the back of the bottle (cat 2, and possibly even the squash pipe) which may allow some through, but slows it mostly.
The new air coming in has to go somewhere, so turns around and fights against the incoming air and eventually the resistance of the paper in the neck.
If the air wins, the paper lands in your mouth.

 

[CatmanV2]

Thanks, that makes sense, and of course with the sensors being prior to the secondaries, removing the secondaries makes no difference to the ECU.

I think I can visualise the bottle example working.
The air flowing in gets past the paper blockage (cat 1).
The air then hits the back of the bottle (cat 2, and possibly even the squash pipe) which may allow some through, but slows it mostly.
The new air coming in has to go somewhere, so turns around and fights against the incoming air and eventually the resistance of the paper in the neck.
If the air wins, the paper lands in your mouth.

Not quite, but the effect is that the harder you blow, the faster the ball comes out:

https://www.youtube.com/watch?v=5jwAnHFzj_4

(first video I found)

Oh and it's not actually impossible, just that it doesn't do what you think

C

 

[boomerang]

Hi Luuk

No. Unfortunately not. I had to sell the AC to fund the house purchase we made....im now on my own without her so I desperately want my AC back....

Good to hear from you Luuk

That is sad indeed, but on the other hand, you used the money for an even better investment i think.
Finding a good AC, will be quite a challenge i am afraid.
On the other hand, prices of a 3200GT in the UK are quite good, compared to prices at the mainland!
Hope you find a good one in the near future again!

 

[boomerang]

Back on topic; do we agree then, that the squished pipe is not the biggest problem at all, of that secundairy cat section?
Would a de cat pipe using the original squished bend, maybe even be better than the Supersprints/Larini's with the twin pipes?

 

[Gp79]

Been looking into replacing the CATS on mine more.

Spoke to an exhaust fabricator in Nuneaton - can install new sections with 200 cell cats for 600 quid. Returning the old sections to put back if I ever sell. (Mine are the euro spec / 2 cats in the same section so not messing with the manifolds.)

There is no point paying any more.

Will look at doing this over the summer.

I also have new lambda sensors to go in so can do this at the same time.

 

[GeoffCapes]

Just an update.

My car will be transported from Giallo on Tuesday by John's (Jkulin) guy to Phil's (contigo) exhaust guy Josh.
Who will then make me a set of cats using a flange made by Martyn (Spaticus) from the drawings of John(Maverick).

Power of this forum is awesome!