E30 M20 how much power would I make if I turbo my built motor

[Obito22]

So I have 1989 E30 325i that has been stroked to a 2.7 I’ll add all the engine info at the end but it’s all built mostly , I want to make the most power I can out of the M20 and my goal is to keep the original motor . As of right now I have a 325is intake , throttle body and ecu but I plan to get itb combined with some throttle actuators and well a stand alone ecu , I have low compression positions so that combined with a turbo I should be making a good amount of power ? Or would I make more power buildings a high reving 3.0 stroker m20 ? My goal is to make the most power I can from the M20 turbo or NA and well I’m willing to dump some money into it

here’s my engine info

Engine info:

. 2.7 Stroker
. 9:01 Compression Pistons "New Rings"
. 133mm Rods
. 135mm Crankshaft
. 885 Head, refurbished, new seals, valves, 3 angle valve job, new rokcker arms.
. 272 Cam from Irland Engineering
. 325Is Intake, Throttle body , ecu and wiring harness.

[AWDBOB]

IMHO ITB's plus turbo is a terrible idea. The ITB plenums are not at all designed for boost and you'll have constant issues sealing the plenum for minimal gains.

I would not change a single thing about your setup outside of maybe oringing the block should you blow a head gasket in the future.

It's more about choosing a quality turbo kit (kangaroo e28goodies twin scroll cast mani) and pairing it with a great turbo (something like a G25-550 or G30-660, or a Borg Warner EFR Series).

Ad boost to your liking until you inevitably run out of fuel system, clutch, and head gasket

[varg]

Or would I make more power buildings a high reving 3.0 stroker m20

If you want the cool factor and engine bay eye candy of a high rpm ITB musical instrument of an engine, that's one thing, but for power turbo is the only way to go. A reasonable turbo setup on an otherwise bone stock B25 will make more power than the most full-race high revving ITB equipped big wallet M20 build and it will do it easily and with no complaints. A smallish turbo like mine, or a slightly larger ball bearing offering on your engine will be beautifully torquey from 3,000rpm up and do 400whp until the cows come home, which is really quite a large amount of power for an E30. It all depends on what you really want.

[digger]

i'm not sure why you have the goal you have but it sounds like a engine swap would be better as you dont build an m20 NA or turbo to make the most of anything. Its just a period correct engine that is about as simple as it gets to work on and challenge to optimise due to its flaws which is fun for some but not if you just want to make some numbers.

[Obito22]

varg If I make 400whp I’ll be more than satisfied with that , what size turbo do you have on your e30 ? I was thinking of going with the cxracing turbo kit which comes with a T4 GT35 Turbocharger and the option to upgrade to a TRB-GT35-T4-68-RR Ceramic Dual Ball Bearing Turbo Upgrade GT35 T4 0.68 A/R. I will probably keep my stock IS intake and throttle body then , what fuel injectors are you using? I was thinking of going with 450cc

[Panici]

I agree with skipping the ITBs altogether.
Their advantages with sound and throttle response in an N/A engine are mostly from running in free air. Once you put a plenum on them (like you would with a turbo setup), you might as well have kept the stock induction.

IMO if you size a modern turbocharger correctly you can start making boost at 2500rpm and keep a pretty flat torque curve with a standalone using electronic boost control. They've come a long way since the 80s

Don't get caught up on numbers. Your modern commuter car makes as much power on paper as an old sports car.
It's more about how it feels, which is why the E30 chassis is so great.
Even 300whp is plenty in a car that is under 2800lbs.

[varg]

varg If I make 400whp I’ll be more than satisfied with that , what size turbo do you have on your e30 ? I was thinking of going with the cxracing turbo kit which comes with a T4 GT35 Turbocharger and the option to upgrade to a TRB-GT35-T4-68-RR Ceramic Dual Ball Bearing Turbo Upgrade GT35 T4 0.68 A/R. I will probably keep my stock IS intake and throttle body then , what fuel injectors are you using? I was thinking of going with 450cc

I'm not following, willing to dump some money into building a high revving 3L stroker (a build that would cost $10,000+) but you're looking at cxracing chinabay turbo kits? I only use 400whp as an example because it's more than any NA BMW 6 will ever make, no matter what someone spends on it. Realistically even 300whp NA is not likely to happen short of S54s and S38s. It comes down to what you really want from the car. As for what I have my build thread has a full list of what my car consists of in the first post, but it wasn't a kit, it was a project that evolved over time.