325i Exhaust system on 320i is it benifical?

[DelaneyG]

Hello iv got a 1988 320i an iv just done the head gasket and rebuilt the head but im thinking of tunning it further i know the 325 exhaust system will fit as they have the same lump externaly but i dont know if the 325 exhaust has enough back pressure for it to be worth it?

Grant

[Brianmoooore]

Complete 325 exhaust will fit, but if there was any advantage in usung it, don't you think BMW, who spent millions of marks developing the exhaust, would have fitted it in the first place?

[e30-320i]

wasn't the 320 built to be under 130 bhp for insurance purposes though could the exhaust be part of the restriction

[liam012]

Have to disagree with bmw i'm afraid.... I found the complete manifold back 325i exhaust sytem to be a marked improvent from the standard 320i setup - no scientific proof mind just the old arse dyno. I could be completely wrong maybe my 320i system was damaged but i certainly could feel the difference.

[Brianmoooore]

It's true that the 320 only exists to satisfy some European tax break, but I always thought it was a capacity limit, or standardised power output rather than "real" power output.
There's no restriction on a 320 that can be dealt with to perform miracles, like the inlet manifold on the E36 328.
320 bhp/cc is similar to 325 bhp/cc.

[e30-320i]

tbh i don't know much about it but the guy that rolling roaded mine reckons that the centre section on mine would be restrictive as its the 2 into 1 system

[Strawb]

it does seem a bit strange that the 320 has only 130 BHP and the 325 has 170 BHP thats quite a difference

[Gt6s]

tbh i don't know much about it but the guy that rolling roaded mine reckons that the centre section on mine would be restrictive as its the 2 into 1 system

If you have the two into one GET RID OF THAT use the twin pipe system its twin pipes for a reason, that being exhaust pulse tuning an ideal 120 degrees between each pulse. Into one screws this fine work up.

[e30-320i]

thats the plan.will a 325 centrebox go onto 320 downpipes as i already have a 325i system to go on when i find a backbox but would rather not change the manifold knowing the likleyhood of studs snapping

[Strawb]

tbh i don't know much about it but the guy that rolling roaded mine reckons that the centre section on mine would be restrictive as its the 2 into 1 system

If you have the two into one GET RID OF THAT use the twin pipe system its twin pipes for a reason, that being exhaust pulse tuning an ideal 120 degrees between each pulse. Into one screws this fine work up.

mine goes from two pipes to one as well? i have a 320

[Brianmoooore]

320 Tourings have twin pipe systems.

[Strawb]

320 Tourings have twin pipe systems.

i think i need to change mine, must be some sort of restrictor

[e30-320i]

320 Tourings have twin pipe systems.

will a touring system fit mine then

[Brianmoooore]

Touring floorpan is the same as a saloon, so I can't see why not, except for the cutout in the rear valence.

[stevetigger]

Touring floorpan is the same as a saloon, so I can't see why not, except for the cutout in the rear valence.

Would an M3 exhaust say like fit a car like mine??

[fuzzy]

wouldnt you have a custom exhaust steve?

[stevetigger]

wouldnt you have a custom exhaust steve?

Yes, but I need to get it rolling! So a bodge job would need to be done until then!

[DelaneyG]

Thanks evryone i finished putting it back together yesterday an its running well but it looks like im gona have to get my on some more 325 parts!
Has anyone chiped their 320i?

[Brianmoooore]

Thanks evryone i finished putting it back together yesterday an its running well but it looks like im gona have to get my on some more 325 parts!
Has anyone chiped their 320i?

Don't waste your money tuning a 320. Either enjoy it as it is, fit a complete 325,or attach the head to a 525e 2.7 bottom end.

[DelaneyG]

i know what your saying but i dont want to dramaticly change the power im still getting used to drifting as it is but if i can get an exhaust system and throttle body of a 325 for cheap enuf that should make it more responsive but since iv done the head its alot quiker anyway, thanks thou

[Gt6s]

A couple of years ago I had to replace the front section on my late 320i and hunting motor factor catalogs it seems that only two types of manifolds are fitted to both 325's and 320's with lots of different variations in the systems either twins or singles. The difference on the manifold is that one uses two seperate pipe flanges the other (as mine) single double pipe flange with twin system this appears to be the late manifold, twin systems are available for either type manifold.
As I found out the single flange twin system front pipe is expensive !
£90 trade / aftermarket.

[Brianmoooore]

i know what your saying but i dont want to dramaticly change the power im still getting used to drifting as it is but if i can get an exhaust system and throttle body of a 325 for cheap enuf that should make it more responsive but since iv done the head its alot quiker anyway, thanks thou

325 throttle body seems to be an effective upgrade, but the 320 manifold has to be opened up to match the TB. This has issues, in that it doesn't leave a lot of gasket area.

[Brianmoooore]

A couple of years ago I had to replace the front section on my late 320i and hunting motor factor catalogs it seems that only two types of manifolds are fitted to both 325's and 320's with lots of different variations in the systems either twins or singles. The difference on the manifold is that one uses two seperate pipe flanges the other (as mine) single double pipe flange with twin system this appears to be the late manifold, twin systems are available for either type manifold.
As I found out the single flange twin system front pipe is expensive !
£90 trade / aftermarket.

OEM E30 exhausts are expensive, but they're good. There're still E30s out there on their original exhaust systems.
I tried to fit a 320 touring back box to a 325 touring about a year ago.
I had both systems side by side on the floor, and they appeared identical.
When I tried to fit it, however, the male bit where it goes into the female bit, at the join, wasabout 0-75mm to big to fit together. Close, but not close enough.