What can you expect Bhp/Torque wise from a 731 head 2.7

[Alex]

What power can i expect from a 2.7 (525e bottom end) using the 731 head (320i)

in the e30 bible it says 150bhp but ive heard some people mention 190bhp with a 731 head

Anyone got any proof ????

Does the 2.5 inlet manifold bolt straight to the 731 head?

Also would a 731 head make it a lazy motor ?

[clarko74]

Have you read Daimlerman's wiki page on his 2.7?

http://www.e30zone.net/e30zonewiki/inde ... an%27s_2.7

There's a fair bit of info there.

[Simon13]

180bhp if your lucky

[chu346]

A 325 manifold will fit fine, and the ports on the 731 head are about the same size a a 325i head just a different shape.

My old car had a 2.7 Eta block fully rebuilt, 320i head (731) with 325i valves and 3 angle grind with a 272/272 dbilas camshaft, 325i manifolds, zone 2.7 chip and BBTB. This done 193bhp on the rolling road. I feel the chip let it down as it was running very rich in places and as every 2.7 is a slightly different spec. no off the shelf chip will be perfect. I think if I had a 6 branch and a remap it would of made 210bhp+.

http://www.e30zone.net/modules.php?name ... highlight=

[Alex]

i would prefer a 325i head but have got a 320i for nothing, would a 325i head give low compression though ?

[chu346]

Use the correct head for the pistons that you are using

325i pistons = 325i head
Eta pistons = 320i head

[Alex]

so basically i need b25 pistons and a 885 head along with the eta bottom end for a decent combo.

also where can you get heads skimmed?

[Simon13]

a 2.5 head is always the best option, it will always flow more than a 731 head

[chu346]

The problem is that using the 325i pistons, getting the block skimmed and vernier cam etc, cost money and you might aswell throw in an M50.

[Alex]

so 885 head, 2.0 con rods, 2.5 pistons, and motronic 1.3, i take it motronic 1.3 is the system fitted to facelift cars that can be mapped

[Alex]

The problem is that using the 325i pistons, getting the block skimmed and vernier cam etc, cost money and you might aswell throw in an M50.

The car i'am getting is staying m20, mainly for insurance reasons

may just rebuild a 2.5 with lightened flywheel and a few bits and bobs.

Whats the vernier cam mallarky ?

[Alex]

back to original question, Would a 2.7 with 731 head be as quick as a normal b25 & will it be quite lazy

[chu346]

Mine was quicker, not really lazy.

Do you think 193bhp without tuning isn't good?

[Alex]

it is good, i want to know if a 731 head and 2.7 bottom end would be lazy and boring

[chu346]

No reason why it would be.

[Alex]

Just read daimlermans wiki page, quite interesting ^^^^^

[AlpineAde]

Alex, have you had a read of this thread?

http://www.e30tech.com/forum/showthread.php?t=48288

And do have a look at Daimlerman's thread.

[daimlerman]

731 head on eta short motor gives plenty of torque,torque fires you out of a corner...
885 head/325 pistons/decked block/vernier campully etc etc costs big money but can give a big bhp fiqure to boast about down the pub.
To get above about 180bhp from the 731 head,you can get your engine machine shop to cut the valve seats out to take 325 size valves,but this costs lowdown torque in favour of more topend power.
Cam choice is critical as well,standard 325 cam gives a good spread of torque,see the graph in the wiki for my engine.On swapping my 2.7 into project cabbie I have swapped to a 323 cam,this is the most aggressive of the standard BMW cams,this has shifted the 'on cam' point up the rev range from 2000rpm to 2500rpm,with an extra shove above 3500rpm,the power now starts to drop off at about 5500rpm,up from 5200rpm.This engine is far easier to drive quickly than my M50'd touring!

[Alex]

old thread

i will be keeping it as a b25 with some bolt on mods, i would like a Miller Maf Conversion, 6 Branch, BBTB etc

firstly i will be doing water pump, oil pump, gearbox filter, timing belt, dissy cap + rotor arm, thermostat and blue temp sensor, pas and aux belts and a general service, filters and plugs etc etc