M37 and M56 exhaust differences?

[biggie]

Anyone know the exact difference between the 2 cat back systems. Is it just size? Or are there mounts/bends that are different.

Trying to work on a possible other option for cat backs for our cars. But need to be sure we can make the same one work for both engines.

Thanks

[Ilya]

As far as I can tell, the stuff after the cats is identical. This is for RWD though, X might be different (from RWD) but the same between M56x and M37x.

M56 parts list:

http://www.infinitipartsusa.com/2011-In ... earching=Y


M37 parts list:

http://www.infinitipartsusa.com/2011-In ... earching=Y




Can someone confirm?

[BlackCat81]

I've had both of them off cars and I can't tell a difference either. I can't say for 100% certain though.

[CRV_33]

Please excuse my exhaust terminology. LOL

Visually the V8 and V6 exhaust systems look very identical but there are some variations. The V6 has a flange at the top of the "Y-pipe". The V8 on the other hand, is welded directly to the last pair of cats.. In terms of the piping diameter I have no idea if they are the same or now.

[biggie]

Please excuse my exhaust terminology. LOL

Visually the V8 and V6 exhaust systems look very identical but there are some variations. The V6 has a flange at the top of the "Y-pipe". The V8 on the other hand, is welded directly to the last pair of cats.. In terms of the piping diameter I have no idea if they are the same or now.

Should they both fit on one another though? Anyone tried to mount a M56 cat back to a M37?

[armybrat]

Please excuse my exhaust terminology. LOL

Visually the V8 and V6 exhaust systems look very identical but there are some variations. The V6 has a flange at the top of the "Y-pipe". The V8 on the other hand, is welded directly to the last pair of cats..

That's because the V6 does not have the second pair of cats like the V8. The front tube assembly bolts directly onto the cats coming off of the exhaust manifold, hence the flanges. On the V8, a second set of cats was added to the front tube assembly and flanged to match the first pair of cats coming off of the exhaust manifolds. Also, the gaskets are different. The V6 uses a flat type gasket shaped like a flange, while the V8 is a ring style gasket that looks like an O-ring. From the front tube assembly back, the parts are the same for both engines.

[biggie]

Please excuse my exhaust terminology. LOL

Visually the V8 and V6 exhaust systems look very identical but there are some variations. The V6 has a flange at the top of the "Y-pipe". The V8 on the other hand, is welded directly to the last pair of cats..

That's because the V6 does not have the second pair of cats like the V8. The front tube assembly bolts directly onto the cats coming off of the exhaust manifold, hence the flanges. On the V8, a second set of cats was added to the front tube assembly and flanged to match the first pair of cats coming off of the exhaust manifolds. Also, the gaskets are different. The V6 uses a flat type gasket shaped like a flange, while the V8 is a ring style gasket that looks like an O-ring. From the front tube assembly back, the parts are the same for both engines.

So your saying cat backs would fit either correct?

[armybrat]

So your saying cat backs would fit either correct?

Not exactly. The front tube assembly that connects to the cats are different for the V6 and V8. Although both have flanges, they are orientated different (according to the exploded drawing on the Infiniti eparts store website) and also take different gaskets. However, the resonator/muffler part that connects to the front tube assembly is the same for both motors.

[twostep361]

a chop and a weld will fix that problem real quick. 100-150 bucks at a muffler shop