Gransport - Euro or US manifolds?

Zep

Moderator
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3,161
What is the difference between the manifolds bar the bolt pattern?
Have a read of the threads. The short answer is that the US spec have Cats in the manifolds and the Euro spec has the Cats in the first section of the exhaust.
 

Mr S

Member
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260
What made you decide to switch out the manifold? Were you having problems with the cats?

I’m 1/2 tempted by your Larini H-pipe, but think I need to wait and see how mine sounds with the decat pipes and unbranded h-pipe... I’m also still unsure whether I will eventually switch over to an x-pipe
It is resonated, so gives a nice throb to the exhaust. All depends what sort of sound you want. Iv got an unresonated X pipe now, and for me it sounds great
 

mjheathcote

Centenary Club
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6,751
cool thanks... so is one better than the other or is it 6 and two 3's?
You only have to look at the two manifold types side by side, and it is obvious that the US manifold with the built in cats is going to be more restrictive than the Euro manifold.
As well as more potential for the US manifold to sustain impact damage, cat damage etc I simply don't believe how Maserati can claim the same power output.
Maybe because I think the US cars, certainly the Gransport, had unsilenced X pipes. The UK Gransports didn't have unsilenced X pipes though, and mostly US manifolds too. They are probably in reality less powerful than the early Euro 4200 as a result!

59706

59705
 

Zep

Moderator
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3,161
Indeed. I think that US spec cars had a different map and are a bit more peaky than a Euro spec car. So they might well have the same power output but less throttle response.

But if it is 20 bhp different then it is barely noticeable. My GS had Euro spec manifolds as have a few others I have seen. But it does seem to be a rarity.
 

mjheathcote

Centenary Club
Messages
6,751
Indeed. I think that US spec cars had a different map and are a bit more peaky than a Euro spec car. So they might well have the same power output but less throttle response.

But if it is 20 bhp different then it is barely noticeable. My GS had Euro spec manifolds as have a few others I have seen. But it does seem to be a rarity.
I think only the very early UK Gransports had the Euro manifolds.
 

JonW

Member
Messages
2,346
You only have to look at the two manifold types side by side, and it is obvious that the US manifold with the built in cats is going to be more restrictive than the Euro manifold.
As well as more potential for the US manifold to sustain impact damage, cat damage etc I simply don't believe how Maserati can claim the same power output.
Maybe because I think the US cars, certainly the Gransport, had unsilenced X pipes. The UK Gransports didn't have unsilenced X pipes though, and mostly US manifolds too. They are probably in reality less powerful than the early Euro 4200 as a result!

View attachment 59706

View attachment 59705
I’m confused by this.... and genuinely interested.

Don’t both the US and Euro Spec cars both have two sets of cats that the exhaust gases have to go through? I know they are in different places, but wouldn’t the net effect be the same?

Also, my car is a late GS with US spec manifolds, and it had a silenced x pipe on as stock...
 

TimR

Member
Messages
1,155
I’m confused by this.... and genuinely interested.

Don’t both the US and Euro Spec cars both have two sets of cats that the exhaust gases have to go through? I know they are in different places, but wouldn’t the net effect be the same?

Also, my car is a late GS with US spec manifolds, and it had a silenced x pipe on as stock...
Mmm...I’m inclined to agree. Not sure it’s expert opinion that’s being put forward here, to be frank. Yes. Both systems have two cats per bank. Gas dynamics vary between seemingly identical engines. Just ask any engine tuner..Back pressure is likely pretty similar between US and Euro spec cars. Tuning may vary as noted, but this can be done with any motor & a dyno desk, too...
Neither do I agree with the comments about the US spec being struck. Sure, they are vulnerable but so too, elements of the earlier cars from what I’ve been told, ride height etc all considered....
All that aside - the density of the cats was clearly an element that Maserati need to address with updated emissions regs & the need to pass new vehicles for sale. Why else would they change the set up,I wonder...This may be the deciding factor, which with respect, you can’t see by looking at them...
 

MAF260

Centenary Club
Messages
6,676
You only have to look at the two manifold types side by side, and it is obvious that the US manifold with the built in cats is going to be more restrictive than the Euro manifold.
As well as more potential for the US manifold to sustain impact damage, cat damage etc I simply don't believe how Maserati can claim the same power output.
Maybe because I think the US cars, certainly the Gransport, had unsilenced X pipes. The UK Gransports didn't have unsilenced X pipes though, and mostly US manifolds too. They are probably in reality less powerful than the early Euro 4200 as a result!
I presumed the same, Mike. Aftermarket manufacturers also claim their manifolds to be better flowing/less restrictive. The work I did on my GS a few years ago disproved all of the claims made as I rolling road tested after each mod to see the difference.

I think only the very early UK Gransports had the Euro manifolds.
All GranSports were subject to a lottery fitting of manifolds, there is no pattern, age, spec that determines what was fitted. Both early and late GS have the Euro-spec manifolds.


I’m confused by this.... and genuinely interested.

Don’t both the US and Euro Spec cars both have two sets of cats that the exhaust gases have to go through? I know they are in different places, but wouldn’t the net effect be the same?

Also, my car is a late GS with US spec manifolds, and it had a silenced x pipe on as stock...
My experience is that your assumptions are correct. I changed my manifolds to Euro-spec, fitted Larini sports cats, Larini H-pipe, and Larini valved rear boxes. I have a BMC air filter and also had the ECU mapped to reflect the mods listed. Net effect is 442bhp, barely 10% up on standard.
 

JonW

Member
Messages
2,346
It is resonated, so gives a nice throb to the exhaust. All depends what sort of sound you want. Iv got an unresonated X pipe now, and for me it sounds great
I hadn’t realised the Larini H-pipe was resonated... I’m pretty sure the forum special I have on my car right now won’t be resonated, so that may be a reason to switch if my new set up doesnt quite hit the mark.

I had a Larini X-pipe on my Granturismo, and it sounded epic. I’m not trying to replicate the exact sound, but I do miss the experience a little bit, and would like to create a similar sense of theatre....
 

Zep

Moderator
Messages
3,161
From my perspective there is little doubt that the longer primaries should be better for power. It is not for nothing that you don’t see race engines with 2 inch long primaries going into a large can. This should give more scope exhaust pulse tuning where the cylinder scavenging and inlet charge retention as expanded upon by the likes of David Vizard. The gains from such exhaust tuning are generally in the low single figure range anyway.

Whether in this case the difference is significant or noticeable is another matter, the US spec cat appears larger than the standard square cat in the Euro exhaust. The transition on the US spec from the cat into the squish pipe is less abrupt. It is unknown if the primary length on the Euro manifold is actually of a suitable length for the cam timing on the engine.

In the end you pay your money and take your choice. And if the difference was 2 or 3% would you notice.
 

Evo Cymru

Junior Member
Messages
534
Emissions Update!

Just for those who may be considering similar mods - my GS passed the emissions today easily with plenty of wiggle room if needed. I have the US spec headers with Larini secondary decat pipes (so effectively just primary cats), x pipe and slightly modified rear boxes. Sounds great and no warning lights either! Car is on 97k so pretty old/worn cats too.

Olly
 

JonW

Member
Messages
2,346
Emissions Update!

Just for those who may be considering similar mods - my GS passed the emissions today easily with plenty of wiggle room if needed. I have the US spec headers with Larini secondary decat pipes (so effectively just primary cats), x pipe and slightly modified rear boxes. Sounds great and no warning lights either! Car is on 97k so pretty old/worn cats too.

Olly
Good to hear... would be great to hear your car, and to see how big the difference is between an x and an h-pipe.