Argos wrote:Well it's like this Del Old Boy. Firstly you never mentioned anything about skimming heads or blocks so please don't come here shouting the odds about your pointless project. Secondly a B20 does not have domed pistons - they have flat tops - any fool knows that..........well, except one fool.....
Thirdly unless you own some old chrome bumper relic your compression is 8.8:1. The 9.4:1 you quoted (from your owner's manual?) is misleading - that is for ECE cars without a cat but not UK cars - they (like plastic bumper 325i's) are still 8.8:1 without a catalyst. It's called a 'cat prepped' engine in case you didn't know. Both of my F plate 320i's were 8.8:1 engines.
As for them being 'the same engine' well no they are not. A 2.5 has bores which are 4mm bigger than the 2 litre and 323i. The distance across the valves on a 325i head is 78mm so please tell me how these will clear the smaller valve cutouts on a B20 piston where the valve cutouts are 74mm across - when you've mullered 60 thou off a 325i head?
Please come back when you have an inkling of what you're on about - it will doubtless be a most engrossing epistle. Oh, and stop pissing about with a 2 litre and buy a proper engine (that'll be a 2.5!). If you or anyone you know owns a boat, your B20 would make a rather splendid anchor.
first off i didnt come here shouting about my project i answerd what was being asked, their are many other other things which i am doin to my second project engine, i have photos of my 2.0l block which has got domed pistons if you want il post em, a little turbulance is required on the inlet side but you still remove rough areas and sharp edges to suit the required amount of flow BUT that depends on what the engine is being tuned for some do some dont, an the quoted compression ratio is from the bmw technical information disk (TIS) so maybe bmw got it wrong? im begining to doubt youv had one of these engines apart or if you have had a 1988 320i engine apart (thats what i have by the way) your one was shit cos mine has got domed pistons which may count for the higher compressoin, lucky me aye
.What makes you think thier differnt engines does the same engine code not give it away oh yea their an incredidble 500CC BIGGER OH MY GOD! Thats not gona make much difference when you tune an engine by the way, valve cut outs? mine has no valve cut outs? Mullerd? Skimmed to raise compression. Inklin what im on about? I,ve been a mechanic for 8 years i still have a job an my private customers come back so maybe their very polite understanding people, and i dont want to tune a 2.5 if i wanted to tune a 2.5 i would everyone does 2.5's its about time someone done anouther 2.0 i like being different.
My girlfriends dad has a boat il ask him but i thing he,s got one
But if you dont think itl work or if its not worth while i couldnt care less, my mates dad who worked at a bm dealership most of life has this mix match stupid idea as you say it an it was rapid so i think il go with him
Ps the intake outside dwell of a 2.0l cam is 38.6mm
the exhaust outside dwell is 32.6mm
a 2.5 intake outside dwell is 43.15 g6 - 43.00 h7
an the exhaust outside dwell is 37.65 g6 - 37.50 h7
note i duno what the g6 an h7 is all about
Your turn
In case you didn't know, the smaller the port, the faster the gas speed = the faster it arrives at the valve, the more gets crammed in on one stroke. This is how four valve per cylinder technology came about.............
