Gransport - Euro or US manifolds?

philw696

Member
Messages
8,497
The left hand one isn’t too bad, the right hand one, oh mama.

But it is doable, with plenty of tools and patience and at the very least a vehicle lift. And yes, you have to lift the engine, but only a little bit.
Blimey you lot are spoilt when I had mine off to do the oil water pump I did it on my back on the floor and no fancy crawler board plus I was 52 back in 14 and the engine crane was in there too.
I was offered a lift at the garage opposite my house but I knew the car was going to be out of action for a few days.
 

mjheathcote

Centenary Club
Messages
6,751
Time for a change as I've had her almost 7 years and done everything I want to do with her. Time to create some new memories in a new toy.

Not a Lamborghini (yet, at least), and not yellow!




The car will be sold as is. It's so well-known it would be pointless to change it. I have removed the stripes though.
Fully understand.
I usually have an itch every 7 or 8 years too.
 

Zep

Moderator
Messages
3,161
Blimey you lot are spoilt when I had mine off to do the oil water pump I did it on my back on the floor and no fancy crawler board plus I was 52 back in 14 and the engine crane was in there too.
I was offered a lift at the garage opposite my house but I knew the car was going to be out of action for a few days.
This is probably because you are better at spannering than us mere mortals! :)
 

FIFTY

Member
Messages
1,760
Just leave them stock. It's just not worth the hassle with potential CEL for cat efficiency and MOT failures.

If it ain't broken and all that. My 4200 had upon purchase failed cats so it was necessary however it has been a lot of hassle
 

jasst

Member
Messages
1,026
Just leave them stock. It's just not worth the hassle with potential CEL for cat efficiency and MOT failures.

If it ain't broken and all that. My 4200 had upon purchase failed cats so it was necessary however it has been a lot of hassle
Disagree entirely I'm afraid, (sorry Fifty) US style have the first cats in the headers, even more prone to breaking up and being ingested into the engine, do you want to take that risk?
 

Gp79

Member
Messages
999
Just leave them stock. It's just not worth the hassle with potential CEL for cat efficiency and MOT failures.

If it ain't broken and all that. My 4200 had upon purchase failed cats so it was necessary however it has been a lot of hassle
Agree 100% mate, there is no / not a lot of performance gain so leave well alone unless the cats are knackered.

Luckily I got the Euro ones on my GS do swapping the cat sections was easier but still a pain in the a$$

59479
 

FIFTY

Member
Messages
1,760
Disagree entirely I'm afraid, (sorry Fifty) US style have the first cats in the headers, even more prone to breaking up and being ingested into the engine, do you want to take that risk?
I have not heard of the US style cats being prone to breaking up in a similar way to the Euro spec ceramic cats...
 

Zep

Moderator
Messages
3,161
I have not heard of the US style cats being prone to breaking up in a similar way to the Euro spec ceramic cats...
Emtee formerly of this parish had US cat breakup on his MCV which resulted in a new engine.

It used to be accepted wisdom that the US spec was more prone to breakup - and because it is much closer to the exhaust ports more likely to be ingested, but Jasst’s experience suggests this can happen with either type.

F430’s also suffer and they have the cat close to the ports too.

In any event, the likelihood seems to be fairly low, but the consequences significant. In the end you have to make a choice based on this equation.
 

FIFTY

Member
Messages
1,760
Would cat failure have something to do with spanking the car about when the cats are close to the end of their lifespan?

You say it is uncommon @Zep but it seems fairly prevalent in these cars. I am guessing it has something to do with the power and heat generated by the engine. Compared to a "normal" car which often achieves in excess of 100-150k miles before the cats start to become less efficient... With these it seems like anything after 45k miles it becomes a lottery on how badly they will fail

Anyway I still stand by my comment. If you have a low mileage car the cats are likely to be fine so just save yourself the grief and spend the money on a road adventure to enjoy the car. Doesn't seem unreasonable!
 

Zep

Moderator
Messages
3,161
Would cat failure have something to do with spanking the car about when the cats are close to the end of their lifespan?

You say it is uncommon @Zep but it seems fairly prevalent in these cars. I am guessing it has something to do with the power and heat generated by the engine. Compared to a "normal" car which often achieves in excess of 100-150k miles before the cats start to become less efficient... With these it seems like anything after 45k miles it becomes a lottery on how badly they will fail

Anyway I still stand by my comment. If you have a low mileage car the cats are likely to be fine so just save yourself the grief and spend the money on a road adventure to enjoy the car. Doesn't seem unreasonable!
I think we agree on pretty much everything apart from US spec cars not suffering from failures.

I believe it is uncommon. In my reckoning there have been around 15 instances, and some of those in EU spec cars haven’t resulted in engine damage (Geoff Capes being and example). This is out of maybe 500+ cars of the type owned by members. Say 2%.

Cats don’t have a life as such, they are mean’t to be changed after a period, but the ceramic core can crack - usually due to mechanical damage - and then start to break up. Emtee’s failure was very early to my understanding, but it would be conjecture to say if this was a manufacturing defect or damage related.

In any event, what you say is true, we shouldn’t all rush out and buy metallic cats. Perhaps the best advice is that if you don’t have evidence of mechanical damage, rattles when cold or your car is low mileage you are unlikely to have a problem. But it is still a good idea to keep an eye on it as the results of a failure are likely to be bank balance changing.
 

conaero

Forum Owner
Messages
29,784
Miles/Emtee was another, Cats broke up, the ceramic ‘sand’ got sucked back into the engine, mixed with the oil and wore the engine out of tolerance, sort of active grinding paste.

I would say it’s uncommon and only know of 3 or 4 instance myself. Considering I’ve been on here from the start/10 years that is a good sign.

Of course, the older the cars get, the more chance of it happening I suppose.
 

philw696

Member
Messages
8,497
Likewise my 4200 didn't ingest any of the cat material
That's the joy of the race style euro manifolds with blowing the broken up debris straight out of the back also porting and polishing the internals of the rest of the system ;)
 

JonW

Member
Messages
2,346
I’m not considering replacing the US style manifolds, but am tempted to replace the squish pipe and secondary cats section with Larini sports cats.

Would this still release plenty of noise and help the engine to breathe better, even though there would still be one OEM catalytic converter in the manifolds?

If I did this, it would mean I had US spec manifold, Larini sports cats, an unsilenced H-pipe, and stock GS valved back boxes. Any on here with experience of what this would sound like?

I’m hoping this means the car could be nice and noisy when I want it to, but still be able to take it out of Sport and reduce the volume to a gentle V8 rumble.. It also means I could return the car to completely stock should I decide to sell.
 

rockits

Member
Messages
6,234
I’m not considering replacing the US style manifolds, but am tempted to replace the squish pipe and secondary cats section with Larini sports cats.

Would this still release plenty of noise and help the engine to breathe better, even though there would still be one OEM catalytic converter in the manifolds?

If I did this, it would mean I had US spec manifold, Larini sports cats, an unsilenced H-pipe, and stock GS valved back boxes. Any on here with experience of what this would sound like?

I’m hoping this means the car could be nice and noisy when I want it to, but still be able to take it out of Sport and reduce the volume to a gentle V8 rumble.. It also means I could return the car to completely stock should I decide to sell.
I reckon that would be a good set up Jon. Why don't you go straight through secondary decat sections though? Must be a fair bit cheaper than CAT versions. Would also a bit more free flowing.

I might put my back boxes back on and replace the silenced xpipe with an unsilenced one. Mine is too loud for me.

I understood the primary cats to be a different sized cat to the secondaries maybe 600 cell to 400 call. I have never had an mot issue with secondary cats deleted.
 

jayblue

Centenary Club
Messages
413
I’m not considering replacing the US style manifolds, but am tempted to replace the squish pipe and secondary cats section with Larini sports cats.

Would this still release plenty of noise and help the engine to breathe better, even though there would still be one OEM catalytic converter in the manifolds?

If I did this, it would mean I had US spec manifold, Larini sports cats, an unsilenced H-pipe, and stock GS valved back boxes. Any on here with experience of what this would sound like?

I’m hoping this means the car could be nice and noisy when I want it to, but still be able to take it out of Sport and reduce the volume to a gentle V8 rumble.. It also means I could return the car to completely stock should I decide to sell.
I have US spec manifolds, Supersprint decats in place of the secondary cat, unsilenced X pipe and stock GS rear boxes. The car is loud when in sport mode but not obnoxiously so, out of sport mode I would say its around as loud as the stock exhaust is in sport mode. There are of course more snaps and pops between gears. There is a small amount of drone in sport mode when cruising, never really bothers me and its easily suppressed by reverting to normal mode. Generally it seems a good compromise, particularly if you want to keep the "gentle V8 rumble" when not pressing on.

On the subject of MOT's in my experience you will need sports cats (such as the Larini ones you mention) in place of the secondary cats. My car has both narrowly passed and narrowly failed on emissions with the secondaries totally removed. Needless to say removing the decats and refitting the stock secondary cats each year is a little frustrating. I know other cars pass no problem with this configuration however. Maybe my primary cats are not operating at peak efficiency any more?