My i head swap!

[ClassicScot]

A quick question, i am doing a i head on an ETA bottom end, i would like to know if i have to change the wiring harness for an eta to an I, i will have a 288 cam with eta block and i manifold.

Let me know

Thanks

Andy

[StereoInstaller1]

Andy, what management are you planning?

[ClassicScot]

explain what you mean.. i have a ECU from and 325 is and i plan on Chipping it. As far as engine management im not going megasquirt or anythin like that at this point.

[nando]

yes, you need the wiring harness too.

[StereoInstaller1]

If your ECU is from an early 325i, it should be a 153, later will be a 173.

These 2 are called Motronic 1.1 and 1.3, respectively.

They both use the same harness/sensors, but yes, you will need to swap.

Keep in mind since you are going to a low compression setup, you will lose power by using that big of a cam. Too much "overlap", meaning both intake and exhaust valves open.

[ClassicScot]

as it is i have the i wiring harness installed.. i am having mechanic friends telling me that it needs to be eta not i because of the bottom end and others saying i need the I harness due to the swap.

Andy

[ClassicScot]

ecu is from an 87 325 is

[nando]

you have to use the i harness because the eta harness doesn't have the correct sensors to use with the i ecu. it has nothing to do with what bottom end you have.

and yeah, a 288 with your CR isn't going to be that great. you'd need a good 10:1 to take advantage of that. it's always possible to shave the head & block a little, but then you need an adjustable cam gear to fix the timing.

[ClassicScot]

ive read that with an i head and eta block i get something closer to 8:1. Maybe an explanation of what i am doing..here it is!

i have an I head with a 288 cam, an eta block with 277 000 km, 3 73 lsd, light weight flywheel for an I transmission with an eta driveshaft. If the fly wheel is a problem i can get my hands on a lightened E flywheel. It has a 173 ECU in the car. It is a 325is shell.

Maybe that gives more of an insight. the reason i ask all the questions is the mechanic working on the car is saying that "because it is an eta block i will need the wiring harness from the old eta" other mechanics say " not needed, due to a I Intake".


After the responses I get off of here and some of the research i have done i should be able to convince them that it can be done.


Thanks for your patience and responses!!!

Andy

[ClassicScot]

a

[StereoInstaller1]

Tell your tech that you need the front crank trigger, build it like an i motor.

Don't use that cam until you get higher compression pistons, and some better engine management.

[ClassicScot]

whats the downfalls of not doing the pistons and the management?

[StereoInstaller1]

Big cam + high compression = out of the stock ECUs mapping ability

Big cam + Stock E pistons = less power than a stock cam on those pistons

If you really want to know more about it, check out this guys page:

http://www.wighat.com/fcr3/camtruth.htm

[MR 325]

If your mechanic thinks the wiring harness depends on which block you have, maybe look for a new mechanic?!

[nando]

ive read that with an i head and eta block i get something closer to 8:1. Maybe an explanation of what i am doing..here it is!

i have an I head with a 288 cam, an eta block with 277 000 km, 3 73 lsd, light weight flywheel for an I transmission with an eta driveshaft. If the fly wheel is a problem i can get my hands on a lightened E flywheel. It has a 173 ECU in the car. It is a 325is shell.

Maybe that gives more of an insight. the reason i ask all the questions is the mechanic working on the car is saying that "because it is an eta block i will need the wiring harness from the old eta" other mechanics say " not needed, due to a I Intake".


After the responses I get off of here and some of the research i have done i should be able to convince them that it can be done.


Thanks for your patience and responses!!!

Andy

they're both wrong - mechanics fix broken stuff, they usually don't have a clue how to build something. it has nothing to do with the block OR the intake.

aside from the head and intake manifold, you need a 325i crank wheel and all 325i sensors (including the AFM), the 325i harness, the 325i intake boot & ICV, injectors, fuel rail, FPR, coolant sensors, instrument cluster, and the 325i ECU. all the e stuff is basically useless.