2.5 Conversion

e21rana · Post by **e21rana** » Thu Jul 01, 2010 4:14 pm

Im currently in progress of installing a 2.5 engine just need a little help and advice on a few things. So here we go...

Fuel pump, i was told that i would need to change it if im swopping engines around cz e30 2.5 has electronic system and it runs at lower pressure than e21 fuel pump. but looking at certain website like...

http://forums.bimmerforums.com/forum/sh ... ?t=1045649

...says you can use the same one but need to check the pressure. the e21 runs at 5bar and e30 engine runs lower like 2bar or 2.5bar.

e21-Mark · Post by **e21-Mark** » Thu Jul 01, 2010 4:33 pm

I still run a 323 one with no problem.

e21rana · Post by **e21rana** » Thu Jul 01, 2010 4:55 pm

ok now moving to the alternator, shall i stick to the 2.5 one or shall the i use the 2.3 one?

Mobster · Post by **Mobster** » Thu Jul 01, 2010 5:08 pm

Just change the starter. The e30 one is smaller and quiter.

e21rana · Post by **e21rana** » Thu Jul 01, 2010 5:11 pm

can i do with the e30 waterpump and leave it on or should i need to change it to the 2.3 one?

e21-Mark · Post by **e21-Mark** » Thu Jul 01, 2010 5:21 pm

Leave the e30 one although as they're pretty cheap it might be a good time to fit a new one, along with a cambelt & tensioner.

e21rana · Post by **e21rana** » Thu Jul 01, 2010 5:25 pm

SWEET! cheers guys, let me connect up engine and then when it comes to the wiring il trouble you then

Mobster · Post by **Mobster** » Thu Jul 01, 2010 5:28 pm

Best person for that is Alpina aka Jimmi

e21-Mark · Post by **e21-Mark** » Thu Jul 01, 2010 5:38 pm

My car still has the 323 fuel pump in the original location.

--ALPINA-- · Post by **--ALPINA--** » Thu Jul 01, 2010 5:44 pm

You need the E21 323i waterpump which has 2 outlets to run its system!!! the 325 has 1 outlet -- look below..

323 Water pump -

http://www.realoem.com/bmw/showparts.do ... g=11&fg=35

325 Water pump -

http://www.realoem.com/bmw/showparts.do ... g=11&fg=35

And with the fuel pump the 325 is a 2.5 bar, 320 is a 2.0bar so if your having a 5 bar fuel pressure regulator and the 325 on the injector rails your gonna have fuel leakage in the injectors cos your running a total of 7.5 bar which is no good for the system and will over fuel which eventually cause issues over time, i cut my fuel pressure regulator off and direct it thru the fuel filter to the injectors upfront!!

J

e21-Mark · Post by **e21-Mark** » Thu Jul 01, 2010 5:47 pm

I remembered as I read it, Murran said about not having to run the steel coolant pipe when you swap to the 323 water pump.

Doh!

My cars definately running the standard fuel pump though so maybe I should look into swapping? I'm pretty sure Varden used the standard 323 fuel pump too?

e21rana · Post by **e21rana** » Thu Jul 01, 2010 6:19 pm

So whats the two outlets for? whats connects to them? On the bimmerforum some guy used the 325 pump how could he have got away with that if you need both the outlets?

--ALPINA-- · Post by **--ALPINA--** » Thu Jul 01, 2010 6:52 pm

325 has one outlet from the waterpump which connects to the thermostat housing, and on the 323 the waterpump has 2 outlets, one also goes to the thermosat housing and the other goes to the expansion tank!

And the expansion tank on the 325 is connected to the thermosat on the underside!!

which is why a waterpump from a 323 is needed

323i setup

http://www.realoem.com/bmw/diagrams/c/d/8.png

325 setup

http://www.realoem.com/bmw/diagrams/c/d/7.png

now you can see the difference.

tommi_e21 · Post by **tommi_e21** » Thu Jul 01, 2010 6:58 pm

alpina thats a really tidy set up for your fuel pump, much impressed, did you make it yourself or is it a kit?

--ALPINA-- · Post by **--ALPINA--** » Thu Jul 01, 2010 7:11 pm

No kit, the box was custom made for me at a company called Tate & Lyle (sugar refineries in east london) i was an on-site engineer and they custome made everything there as its a 24hour site with all machiners for repairs e.t.c. i was well impressed so i deisghed it in a way that i have my fuel gear in the boot, also easy to change the fuel pump and filter rather lying down flat under the car...

Nice eh!!

J