320 ported and polished head?

[tom_johnston]

gota replace the head gasket on my 320, was thinking of having the head ported and polished while its off. will there be a noticable difference?

cheers

tom

[mrLEE30]

for the money you pay for port and polish could be better get a 325 engine and guarenteed results.

but to (try and) answer your question..

IIRC the 320 suffers from inlet ports which are sized incorrectly for the engine, causing poor gas flow at low RPM and hence why they are gutless below 3K, porting may make it worse down low but better in the upper RPM range but unless you change the inlet and outlet portions of the engine (fuel/air delivery system and the exhaust plus a remap of the fuel injection control system i doubt polish and port will make very much difference.

either enjoy the engine for what it is or swap it for a 325.

FYI the best ''cheap'' mod for the 2.0 engine is to fit a 2.5 throttle body and modify the inlet manifold, its a home job and covered in the articles section.

mrlee

[StuBeeDoo]

No point porting a 731 'head on an M20B20. The ports are too big already.

[tom_johnston]

cheers thanks for the advice, want to keep the 320 in, an engine swap is a hefty job. i think it goes quite well already for a 2 litre. maybe further down the line ill do a conversion.

[e30bmlover]

you wont look back when you get a b25 in there trust me.

[handpaper]

2.5 throttle body and a decent chip will make a noticeable difference - letting the engine rev more freely at the top end makes the most of the oversized ports. Add a six-branch manifold for even more fun and nicer noises - and you can swap it onto a 2.5 later if you decide to go that route

[fuzzy]

you wont look back when you get a b25 in there trust me.

no you wont look back because everyone your racing will be way out in front

[Rav335uk]

I just did a chip change and that altered the low down grunt a bit and ran a lot smoother too.Thats before i tookm it out and replaced it with a m30

[Madhatter_]

731 Cylinder Head Work might be of some use if you want to have a look. But I agree with the others, you need the added capacity to go with it.

[bmwsport]

Id get yourself a dremel and smooth the port castings down but don't actually enlarge the ports, just get rid of the 'roughness'.

[Brianmoooore]

, an engine swap is a hefty job.

No more work than a head swap, and not so many 'critical' jobs involved.