M20B20 Engine what is the option to gain power? #special case

[E30DaNang]

Hi Guys,

for sure in first moment you will may think oh another guy that cant use the search function, but wait, as in my case it is a way more complicated as it looks first!

So lets start to explain a little first, have a E30 320i coupe from 1987, Automatic Transmission, Sport edition with all disc brakes, the 51mm shocks and i live in "Vietnam", the restrictions here on one hand very hard, on another ridicules easy. Major rule is "you cant swap a engine" it needs keep the engine number that is in the paper and copied by a stencil to the traffic observation department. Means in the end you can put a turbo on it but you cant swap the block! The Car will be a project as there is literally NO PARTS available, so all need to be imported and thats why it needs to be planned into detail!

Start with a good point- Thailand is just 1 hour flight near and the Thais are nuts in terms of Turbo upgrades by example.
Negative, not easy to import anything that does not fit in a suitcase or 2....Also in terms of weight....

So i break my head about what would be the best, easiest and cheapest option to make something out of this cute little 320i (iam a former E30 318is driver and know how much fun it can be)

1) I was thinking to put a turbo on it, the question is keep internals genuine or upgrade it, my seeking are about 200-300hp.
2) If upgrade the internals and stick on B20 stuff OR go for other ratios of pistons etc, if so, what would be the option?
3) what to do in terms of gearbox, as the original Automatic transmission probable not survive that long (and not fun too) and again, all need to imported, small stuff that fit in a suitcase is easy-a gearbox is not....

The other option is NO Turbo, and keep it N/A but how much power you can gain out of the B20 block, what can increase with the best value for the money a budget of lets say 5000$ plus minus. Or how can make a Stroker without changing the block by example to B25.
So my thoughts was:

1) ITBs (what brand and inlet mm you guys drive and can recommend)
2) Camshafts by example Schrick (what specs?)
3) Double Valve springs
4) Racing Valves
5) Probably any other pistons ++ than stock (as a overhaul of the engine would have been anyway my plan)
6) Maybe another Cylinder-head with big inlets etc?

So i hope everyone understand why i cant feel suitable with the regular topics and hope someone have useful thoughts!

All support and information is very much appreciated!

[martauto]

Welcome to the zone mate and we need some pics of your car please
I have moved it to the general technical help section as you will have more chance of people seeing this and boy do you need help with the restrictions you have over there.
Enjoy the forum

Mart.

[steve_k]

welcome to the mad house.

as for what you've put,

turbo route? not a clue sorry.

but the N/A route? this is where it can get just as costly & complicated as going the turbo route.

have you thought about a stroker? the 2.8 is probably the easiest to go for.

https://www.e30zone.net/e30wiki/index.p ... ding_a_2.8

have a read through that link,
but the biggest hurdle is budget, level of ability & parts available to you.

[Brianmoooore]

The M20B20 block, with the all important numbers on it, is essentially the same as a M20B25 block, but bored out less. The B20 can normally be bored out to B25 size, unless there turns out to be a thin point in the casting, and if you can get that far, a N/A 2.7 or 2.8 can be built.

[HJ1981]

According to all my research, the head is the key to making power, especially the porting/polishing as well as the chamber modification. One needs a very good chip/software tuner to really squeeze the most out of it, be it 2.5l or larger.

Personally, when it comes time to rebuild the engine in my 325i, id go for the largest stroker setup using stock 2.5l pistons, keep compression high and do some mild head work (nothing crazy, a good port and chamber, keeping the same sized valves/springs) and i know someone in Munich who does software for BMW and actually worked with BMW developing the E31 engine and software. But each of us have our own goals.

But once the head is sorted, then start looking for ITBs or bigger bore throttle and so on, the head (and cam) are really the biggest limiting factor on the M20.