i head swap harness question

[e30onBBSs]

Okay so I'm sure some of you have read ForceFirebird's flow thread and the b27 intake mani + the b25 throttle body flows better than the b25 mani and b25 throttle body.

Could I keep the eta ecu and just throw in bigger injectors, the 885 head, b25 throttle body and call it a day? Maybe a 90A alt?

[jeffnhiscars]

The b27 ecu will not support larger injectors

[e30onBBSs]

The b27 ecu will not support larger injectors

What's it limited by?

Is there no way to avoid swapping the whole engine harness/rewiring the starter etc? Is it really that hard?

[jeffnhiscars]

ETA injectors have different impedance than the others and that has to match the ecu. The 027 ecutypical in etas is Motronic 1.0 and has a different connector.

Injectors harness and ecu have to all be 1.0 or 1.1/1.3

[modernist]

Plus, Motronic 1.3 is superior in pretty much ever way.

[e30onBBSs]

Thanks for the replies guys I've been doing lots of reading and I feel pretty prepared to do the swap! I'm going to run 5.0 mustang injectors and get as much new hardware as I can- making a list of part numbers right now. I'm excited as shit!!

[modernist]

Sweet! I've been curious about the b27 manifold on the 885 head too. Keep us updated

[e30onBBSs]

Sweet! I've been curious about the b27 manifold on the 885 head too. Keep us updated

Have you read forceFirebird's thread on it? Wicked awesome! I hope I can squeeze in the swap before winter but I may wait until it's spring. I have all the parts just need new gaskets and what not + all new hardware. I'm stoked

[modernist]

Have you read forceFirebird's thread on it?

Yup, that's where I found out about it too. Are you gonna get the intake manifold gasket port matched to the head and throttle body?

[e30onBBSs]

Yup, that's where I found out about it too. Are you gonna get the intake manifold gasket port matched to the head and throttle body?

Going to get the big intake hole cut to match the b25 t body and Forced said that's all they did

[jeffnhiscars]

Here's a b25 throttle body sitting on a b23 intake which comes with the same size TB as the b27. There is not enough meat on the bottom of the b23 manifold to open it up to fully match the b25 TB and still hVe it seal...but probably an 85-90% volumetric match.

I can't say for sure that the b27 intake is any different ialthough with the same mating flange as the b23 it seems likely they are the same, I n which case you want to think about building up the bottom of the b25 TB with JB to effectively port match it and eliminate the step.

[modernist]

I happened to have both throttle body gaskets lying around, so I traced them. There's definitely not enough meat on the bottom of the b27 manifold to bore it out all the way, unless you add material.

[jeffnhiscars]

So you build up the inner bore of the b25 TB at the bottom so it flows nicely into whichever manifold. I haven't done the math but Im guessing you lose less than 10% of the bore area and since you can't ever flow bigger than your manifold you really lose nothing but sleep trying to figure out why BMW is messing with our heads.