gooner1 wrote:
Sureley the M30 engine is only 26KILOS heavier than the M20 one.?
M30 212kg, M20 171kg so it's ~40kg heavier + bigger gearbox etc..
In cabrio it's easily balanced by relocating battery to trunk.
Don't use M10 gearbox if you want to cruise big speeds with sensible revs. You'll also have problems with flywheel, clutch and starter, so use 535 box.
Original 325 fuel pump is good enough. E28 535 radiator should also be used, fits straight without any problems
And then to M20 vs M30 power-debate (shame that multi-quote doesn't exist on this forum).
M20 produces 170-180hp with little mods and power comes 4500 - 6000.
M30 makes 220hp with little mods, power comes 1000-6000. 200Nm @ 1000rpm, 320Nm @ 4000rpm vs. M20 230Nm max @ 4000....
0-100km/h M30 with 3.6 differential ~6,5s vs. M20 powered E30 7,8s.
Top speed M20 powered cabrio 218km/h, M30 powered cabrio 235km/h.
And the list just goes on and on. M30 is easily the best option if making "budget-power". It just pulls the car so effortlessy - just what you need in cabrio. No big "power-jump" @ 4000rpm, just linear powercurve 1-6krpm.
Low budget: M30 - you can turbo it if you want more power later. Nothing big with the swap and M30 lasts 1 000 000 miles when serviced correctly.
Medium budget: M52 - better fuel consumption, 230hp / 300Nm easily. EWS and wiring are problems.
Big budget / project: M60 is "the thing" in E30 cabrio, 300hp / 400Nm and that V8 sound. Not easy swap, costs alot but it has bullocks (or however you say that in english

)