Debating...I head swap on e motor/full i swap

[Bmwman92]

Uhhh what all did you do? because I can pull those #'s with $50 worth of work on my Super e. At the moment I have a motronic 1.3 chipped ecu swap and a cone filter. I'm in the process of swapping the auto out to a 5 speed. Than I will be figuring out if i'm going to build a boosted 2.7i or boosted 24v. I can get the 24v with trans for $250

[e30trooper]

Noobs , thats WHEEL HORSE POWER!!! Not at the crank durrr.

170bhp(crank) minus (20% for drivetran loss) est is 139whp ....

[Bmwman92]

o.O Shut up hoe! lol just kidding i get it

[e30trooper]

o.O Shut up hoe! lol just kidding i get it

Its ok...

It all depends how much you want to spend and what you have available..

I decided to go I head swap since it was easier. The way I drive I should have pulled the block and rebuilt it. I got lucky #6 cyl has bad rings. Car still pulls hard but can burn a qt of oil in a week easy if im on it 24/7 (typical) lol

i head swap stock with a chip. Still had the open 2.93 diff ( eta ) reason why I could hit 70 in 2nd gear at 6500rpms

[Bmwman92]

Not bad what all did you put on? Im going for I head eta manifold and I throttle body. eventually cam and cam gear

[e30trooper]

Not bad what all did you put on? Im going for I head eta manifold and I throttle body. eventually cam and cam gear

everything! Only thing eta is the block w/trans and exhaust now.
:D

[strang3majik]

So what does a stock I car make at the wheels? I thought the factory ratings were wheel horsepower...thought the germans were better than to tease us with crank ratings...lol


But, if a stock I car makes 160 at the crank then its actually making a wee bit less than the I head on a 2.7 block...in which case I'd be happier with the 2.7i.


Ugh...decisions decisions...lol

[mulletman]

So what does a stock I car make at the wheels? I thought the factory ratings were wheel horsepower...thought the germans were better than to tease us with crank ratings...lol


But, if a stock I car makes 160 at the crank then its actually making a wee bit less than the I head on a 2.7 block...in which case I'd be happier with the 2.7i.


Ugh...decisions decisions...lol

I've never heard of any manufacturer publishing whp numbers. It's always crank numbers.

[strang3majik]

I'm an American car guy who usually spent his time with muscle cars. They were rated at the wheels as underrated at that. Lol. That's what I'm used to.

Also any newer fwd stuff I've dealt with there isn't a big difference between the two unlike rwd.

But either way, I hear people say 160, 170 etc. never knew I it was crank or wheel hp.

But anyway...what's a I motor rated at at the wheels?

[e30trooper]

stock m20b25 should make about 145 whp/ 148lb/ft

heres a thread about it.

http://forums.bimmerforums.com/forum/showthread.php?t=1471732

a head swap might make a tad bit lower but will have more tq at a lower rpm. Power falls off after 6200 rpms.

[strang3majik]

stock m20b25 should make about 145 whp/ 148lb/ft

heres a thread about it.

http://forums.bimmerforums.com/forum/showthread.php?t=1471732

a head swap might make a tad bit lower but will have more tq at a lower rpm. Power falls off after 6200 rpms.

In that case it sounds a 2.7i would be about the same, just a little torquier.

So if I do a cam swap (I know a guy with a 323i cam), and a chip, I'd be higher than the I motor?

Sounds like a top end swap is happening then...lol

[richard.bratton]

Stock M20B25s that we run in Spec E30 make around155 WHP (wheel horsepower) on a Dynojet. Fresh and very well prepared, I've seen numbers in the low 160s with all stock bits. A very high mileage M20B25 wilth mediocre compression (150ish psi) will make 145ish WHP.

The posted dyno plots for the 2.7i are very much on the low side when compared to 2.5i motor. Engine condition is a large factor, but its my opininion that a 2.5i motor will out perform a 2.7i motor of equal condition. Increasing the compression ratio on the 2.7i would make a big difference, but is difficult without aftermarket pistons.

[phenryiv1]

It has been a LONG time since I researched a 327i/2.7i build, and even then I had an '88 325 with the Seta motor, so everything was different fo rme.

I read a few threads as I debated swapping my '87 325 (with the B27) for an M20B25 from an '89. I was under the impression (and still am) that just swapping the 885 head from the 325i onto my otherwise stock M20B27 bottom end will result in both lower compression AND interference between the valves and the OEM eta pistons. Did I recall that information incorrectly?

[Chriskbmx]

i pearsonaly thing you will be happier with the 2.7i because i know how much you like tourqe lol. and with the plans to boost its the smart way to go. you just have to ask yourself. is that motor gonna hold the boost with that many miles?

[DetailAddict]

lower compression, yes, and excellent for FI. not sure about interference between the valves. however, you don't get the matching head to head. I am running 87 325e with i head (and just about everything else).

Leo

It has been a LONG time since I researched a 327i/2.7i build, and even then I had an '88 325 with the Seta motor, so everything was different fo rme.

I read a few threads as I debated swapping my '87 325 (with the B27) for an M20B25 from an '89. I was under the impression (and still am) that just swapping the 885 head from the 325i onto my otherwise stock M20B27 bottom end will result in both lower compression AND interference between the valves and the OEM eta pistons. Did I recall that information incorrectly?