2.5 head on 2.7 block= how many HP?

[bmwarrior]

Hi, wassup guys?

I have read a lot of the 2.5 head on the 2.7 block conversion, but how many power do u get out of this conversion?

the 2.5i came with 168hp and the 2.7 came with 121hp, but how much do I get out of this conversion? what ECU should I use the 2.5 or the 2.7 ecu??

thanx in advance

[maxfield]

Depends how far you want to go with porting cam exhaust etc.

But you need the pistons machining when using 2.5 head i think or the head needs machining.

2.5 tb and inlet.

You should get a 2.7 chip from the zone shop.

[dazleeds]

185 to 230bhp depending on what you do to the head and block

read the engine swaps section for more details

[bmwarrior]

ok, thanks guys!

if anyone know something more please tell me.

BMWarrior

[daveo]

Ive been collecting info for the conversion my self. what i have found out is there is two types 525e engine the early engines before 85 uses a type 200 head and has domed pistions a 325 head 885 casting will not fit without maching the block and replaceing the pistions. The later 525e engine after 85 uses a type 200 head and dished pistions (concaved) and ive been told a 885 casting head will bolt straight on with no problems.

Dave

[Gunni]

www.e30.de says about 170hp with a 731 head on a 2.7 using 325i electronics.

wich is reasonable enough, smaller valves. smaller cam, bigger size works that back up.
More aggressive cam and you got yourself a winner,.

[daimlerman]

325 head really needs 325 pistons.Snag is that 325 pistons are shorter from the pin to the crown than 525e pistons.The skirt shape on the 525e piston is shaped to clear the long throw crank.So to use 325 pistons the skirt of the piston needs modifiying,the piston at TDC is too low in the bore so the top of the block needs machining to match.This makes the cam too close to the crank so affects valve timing.To correct this,you require a vernier cam sprocket....I used a stock eta short motor with the crank reground,new shells,new piston rings,320 type sump,320 head with 325 cam.I have an engine with lots or usable torque just where I can make use of it without needing to rev the arse out of it.The 2.7 conversion is all about torque,not max BHP.Before you commit yourself,have a good search and think about the 2.8 way,it may be a cheaper option than rebuilding an eta bottom end...

[snoops]

id say about 200 or up to 220/230 bhp if done properly

[maxfield]

id say about 200 or up to 220/230 bhp if done properly

It is very hard to get 230 out of a 2.7 without spending mega bucks

[tomze30]

I agree with the comment about the conversion being about torque...mine lights up at 4000 rpm and takes a lot of catching.
It's a LHD silver tourer with a 525e bottom end, original crank and dished pistons. Head is straight off a 325i.

Cheers, Tom.

[Jhonno]

you can fit the 2.5 head on the 2.7 block no probs without any machining, however if you want to restore some of the compression that is lost you need to deck the block and use an adjustable pulley

[bmwarrior]

Ohh, ok,
thanks guys this info helped me a lot because me and a friend are donig this conversion thats why I wanted 2 know more.

bmwarrior