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Guys

I need some advice on the best injectors to go for as I'm building a fast road 2.7 m20 engine, 525e crank, decked block short rods, early high compression pistons, 885 head, Schrick 284 cam, fritz 6 branch manifold, possibly gas flow the head (looking into that at present any advice would be much appreciated) currently going down the motronic 1.3 ecu with a 2.7 alpina replica chip.

My concerns are that the engine now thirsts for more fuel compared the standard 170hp m20b25 the injectors were designed for however I'm in noway qualified to make a call.

And any help would be greatly appreciated, i'd like to keep things looking fairly subtle under the bonnet so I'm trying to steer clear of independent throttlebodies and standalone ecu's etc.

Standard E30 325i injectors will be fine as long as they are good and clean.
Thats all Alpina used on their 2.7's, and it looks as if your engine will have a similar demand.
The only thing you may want to consider is a fuel pressure regulator. You can tweek the system pressure for the injectors up to provide more fuel if required.

Using a basic calculation for 210bhp and an injector duration of 80% you would need:
210bhp x 5 / 6 (cyl) / 0.8 (dur) = 219cc/min

I think the std 325 injectors are ~19lb/hr or ~200cc/min at 3bar which should be good for 192bhp at 80% duration and 240bhp @ 100%
Running the std injectors at 3.5 bar should make them good for 207 @ 80% duration and 259bhp @ 100%

Note: a lot of E30 325 regulators run at 2.5 bar - so 80% duration gives 175bhp (see how the maths works here)

Hope this helps

Ben

PS. The only other easy thing I would add to that engine spec would be a big bore throttle body (BBTB). A think its a guy called Maggspower on E30zone who currently machines then and can make them from your std throttle body. Basically they are bored out with a larger butterfly in them, so externally they look standard.

That's what I heard as well, injectors should be up to the job. Some M20 B25's and most M30's use a 3.0 Bar FPR and these are interchangeable with the 2.5 Bar version. That 3.0 Bar version is being used on M30B35 and M88B35 as well so I'd say it should be good enough for your M20 plans as well. But if you check with your local Bosch specialist, they may have a 3.5 Bar version of this model as well.

Agree with Ben, the throttle body will be the bottleneck in the intake so I'd defo consider a bored version. Already works miracles on fresh stock engines like the M20B25.