i head swap question.

[slo325i]

click on my 2.7i how to in my sig all answers will be answered then if you still have questions ill be glad to help!

Hey man

I've been trying to reach you, actually. I've also been reading up on your posts. I think you required to have the a different ecu (...173). But mine is a 153 ecu and i'm pretty sure it's a i ecu. So i kinda got lost from there... Too new at this.

[mooseheadm5]

OK:
You need the i head for the larger intake valves, larger intake ports and dual valve springs. That will take care of your redline. The timing belts are the same for both motors. You want the i intake for the larger runners. If you are running the i injection already (which you ought to be considering it is an i with an e motor dumped in) then you already have the correct AFM (the i AFM.) You need i fuel injectors. If the crank balancers has the toothed wheel and the #6 plug wire has a sensor on it, you are running i injection already and likely have the correct injectors and everything else you need. I milled my head 0.040", but I'd advise against going that far unless you are very good at adjusting your valves often. 0.030" is not out of line, though. Any other questions?

[slo325i]

One question, do you HAVE to mill the head? I understand the compression will be reduced a bit by going 2.7i. How bad if I left it alone??

OK:
You need the i head for the larger intake valves, larger intake ports and dual valve springs. That will take care of your redline. The timing belts are the same for both motors. You want the i intake for the larger runners. If you are running the i injection already (which you ought to be considering it is an i with an e motor dumped in) then you already have the correct AFM (the i AFM.) You need i fuel injectors. If the crank balancers has the toothed wheel and the #6 plug wire has a sensor on it, you are running i injection already and likely have the correct injectors and everything else you need. I milled my head 0.040", but I'd advise against going that far unless you are very good at adjusting your valves often. 0.030" is not out of line, though. Any other questions?

[416stroker]

OK:
You need the i head for the larger intake valves, larger intake ports and dual valve springs. That will take care of your redline. The timing belts are the same for both motors. You want the i intake for the larger runners. If you are running the i injection already (which you ought to be considering it is an i with an e motor dumped in) then you already have the correct AFM (the i AFM.) You need i fuel injectors. If the crank balancers has the toothed wheel and the #6 plug wire has a sensor on it, you are running i injection already and likely have the correct injectors and everything else you need. I milled my head 0.040", but I'd advise against going that far unless you are very good at adjusting your valves often. 0.030" is not out of line, though. Any other questions?

you said what im to lazy to say. It wll be low. Why not mill the head its only like 40 bucks.

damn .040's a lot I didnt feel like checking my clearences so I whent with .020. How close were they? did you check it with clay?

[mooseheadm5]

Absolutely not. Lower compression will be great for poor quality fuel and future turbo, so you don't have to mill it if you don't want. I think the figure is something like 8.5:1, but can't remember.

[slo325i]

I think i'll eventually go turbo anyways. Got a t3/t4 .63 turbo sitting in the garage now. But it'll be after 2 reliable years with this car. Thanks so much guys.

[416stroker]

Absolutely not. Lower compression will be great for poor quality fuel and future turbo, so you don't have to mill it if you don't want. I think the figure is something like 8.5:1, but can't remember.

I thought it was lower than that but I dont remember.

[kenika65]

Put a 173ecu in and then tell me what your redline is!

[mooseheadm5]

I think the super eta is 8.8 and the regular eta with i head is 8.5, but it could be lower.

[slo325i]

Put a 173ecu in and then tell me what your redline is!

well b4 i make this car all rev happy i wanna build up the mechanical side first. I think i'll be ok with the 153 ecu. I'll still be rev'n better than a eta anyways. Thanks for your input.

[kenika65]

my eta revs to 6800...

You dont have to put the i head on just to have a higher rev limit...

And as for compression...

http://www.bmwccn.no/rogaland/Mahle_m20.html

[slo325i]

my eta revs to 6800...

You dont have to put the i head on just to have a higher rev limit...

And as for compression...

http://www.bmwccn.no/rogaland/Mahle_m20.html

You've been pm'ed.

[mooseheadm5]

But you really ought to do the dual valve springs (which most people pull the head to add, though if you are clever, you can do it on the car.) Also, having larger valves and intake ports is good for power. Plus, the i cam is better.

[Adrian_Visser]

Ever heard of valve float? dual valve springs are to prevent the valves from floating at higher rpm's, you see springs have a natural resonant frequency at which they no longer function as springs and just sit there. The dual springs while not only providing more force to close the valves have two different resonant frequencies so one spring will always be forcing the valve closed and not hitting the pistons on your decked head.

AFAIK eta rocker arms are weaker than i ones too so you can rev an eta head to 7000rpm's but it is a time bomb.

[kenika65]

The I cam just moves the power curve up... and yes the extra valve spring is smart if you plan on revving over 6k.