best way to go about boosting a 325e?

[sofargone561]

started my build thread tonight. next update will be Wednesday more pics coming!

http://www.r3vlimited.com/board/showthread.php?t=231612

[The Humjet]

Hmmm... I sent you a pm anyway :)
Many guys use stock eta bottom ends with the 885 head its not as bad as some of these guys say. And its barely an issue when your going forced induction. If you don't wanna go replacing pistons then staying stock is fine.

[euro2fast4u]

Bolt on yes, but wiring and other items are needed from an i motor.

Great write up here:
http://www.strictlyeta.net/technical/328i_1.html

if you are going to go with a standalone you will be able to choose what parts you want and dont want to use

^^^^^^^^^^

Great thank you. Luckily for me my dad is a total gear head and amazing at wiring and electrical work so im going to ask him to help me with that part. I dont know is i mention this but i do want to keep power windows, power locks, power steering and A/c. i will be getting tid of the washer fluid system and cruise control.

The only raw wiring part is adapting the fuse box plug and there's a wiring diagram for that.

not even the fuse box, theres a plug called c103 that connects the engine harness to the car harness. this is where you will doing modifications to the run a standalone. as the body harness shouldnt be touched.

In that post it said the 325e pictons wont work with this head? i thought they didand the iunternals where good for like 400whp? im confused now?

if the head was shaved multiple times to either a) get the compression ratio up or b) its been warped twice then you might have some clearance issues. when you assemble the motor make sure your checking for clearance as any engine builder should.

^^^^^^^^^^^

Ok thats whata i was told to do but for some reason the build thread posted above said i needed to grind the pistons or something and this link works i copy and pasted it before and it didnt work

EDIT: thats the same link someone just posted



2.) What parts are needed?
For a complete and detailed list, see page 2. But generally speaking, for an 84-87 325e you need the entire fuel injection system from a 325i as well as the intake manifold, throttle body, and complete cylinder head (with cam, valves, and dual valve springs. However, the stock 325e pistons will not work with the 325i head because of the different design; the 325i has a domed cylinder chamber to match the domed pistons while the eta has a flat cylinder chamber to match the flat pistons. Throw the flat 325e pistons into a 325i head and you have a mismatch that causes a lower compression ratio, and this for this procedure, lowering is a bad thing. So that leaves you with 3 choices:

#1 is to use the pistons from a 1988 528e or 325 (Super Eta), which works fine but has a less than ideal compression ratio of 8.8:1. The good thing is that they are cheap if you can find them, but then again, they are used pistons and they aren't very commonplace since they were only available for one model year.

#2 is to use the 325i pistons and shave the top. 3mm is supposed to be the accepted tolerance with stock 325i rods, though I have also heard 2mm as well. Pete McHenry of Precision Performance Services in Winston-Salem, North Carolina (333) 761-0643 is the pioneer of this conversion and would know this information firsthand, as would Jim Rowe of Metric Mechanic in Richland, Missouri (573) 765-1269. There may be other BMW tuners, technicians, and machinists in your area who know this, so ask around.

#3 is to order a set of custom made pistons from companies such as JE, Arias, Kolbenschmidt, and Wiseco. While this is probably the most expensive route, you can customize exactly what type, compression, and size of piston you want. They can be ordered through a variety of vendors, including Ireland Engineering, Top End Performance, Metric Mechanic, and Redline Racing.

See it says i need to replace them with other ones, grind them or get custom ones made? =/

ill try to answer all the questions here but im kinda confused. for a boosted application you truely want a lower compression ratio bc this reduces the ability of knocking.

this site is just full of bad information. for a na car your right you want a higher CR because then you get some power back.

the reason for swapping the head is for the higher rpms honestly and better flowing heads.

From what I have been reading you can use eta crank, rods, and pistons basically the whole bottom end. This does lower the compression because of the flat top pistons and the domed chambers on the 885 I head. This combination will work but its been said that it has a hard start and rough idle.

For the head swap link go to the search bar in this section (M20) and search 1.3 motronic up grade. It is were I have been getting my info

it has a hard start and bad idle bc the ecu there using isnt made for this combination.

best FAQ

http://www.e30tech.com/forum/showthread.php?t=3237

[sofargone561]

if you are going to go with a standalone you will be able to choose what parts you want and dont want to use

^^^^^^^^^^








not even the fuse box, theres a plug called c103 that connects the engine harness to the car harness. this is where you will doing modifications to the run a standalone. as the body harness shouldnt be touched.





if the head was shaved multiple times to either a) get the compression ratio up or b) its been warped twice then you might have some clearance issues. when you assemble the motor make sure your checking for clearance as any engine builder should.

^^^^^^^^^^^



ill try to answer all the questions here but im kinda confused. for a boosted application you truely want a lower compression ratio bc this reduces the ability of knocking.

this site is just full of bad information. for a na car your right you want a higher CR because then you get some power back.

the reason for swapping the head is for the higher rpms honestly and better flowing heads.





it has a hard start and bad idle bc the ecu there using isnt made for this combination.

best FAQ
http://www.e30tech.com/forum/showthread.php?t=3237

thanks for all the info! i will ask more questions in a little i just wolk uo all i can think about right now is what i want to eat lol

[nickflic3]

.

I was addressing his concerns more from a straight head swap point of view, but in the case of standalone, your very right. I've done the i swap in my car using that website, but they do seem to be wrong about the stroker part and not being able to use eta pistons.

[sofargone561]

I met a guy who sells 885 heads with upgraded rocker arms and ports and polishes them and also with grind my cam for me. I think im going to buy one of his heads soon

Also what cam do you guys recomend? I was thinking maybe a 280? hat do you guys thing? also are there after market springs and what not? I want to rebuild everything with quality parts and have a seriously bad ass ETA, even if it takes longer to rebuild it and make it cost more.

[euro2fast4u]

you still havent determined the power you want to make. after you do then youll be able to decide what parts you want. a 885 isnt an eta its an i head, it gives you the ability to increase the redline from 5k to 7k. they also have a better flow rate then the eta head.

[devon.818]

So much bs in here it's ridiculous!!!!

You can have a redline of 7k+ all day with stock I head! anything over 7500 maybe upgrade rocker arms

You seem real tenative, not trying to get you down but hold off on this

[sofargone561]

you still havent determined the power you want to make. after you do then youll be able to decide what parts you want. a 885 isnt an eta its an i head, it gives you the ability to increase the redline from 5k to 7k. they also have a better flow rate then the eta head.

I know thats why i want to switch this. and i do know the power i want to make i just dont know shit about bmw motors. i want about 300whp but i want to be able to make more if i wanted.

[sofargone561]

So much bs in here it's ridiculous!!!!

You can have a redline of 7k+ all day with stock I head! anything over 7500 maybe upgrade rocker arms

You seem real tenative, not trying to get you down but hold off on this

ive heard this from over people. the head i want to buy has some machine work and i will be purchasing upgraded rocker arms for it as well. i was just wondering is upgraded springs and a new cam should also be purchased. i am holiding off. i have a lot of other work to the car i need done before i even pull the motor. Also i wont be purchasing any parts for a little bit i have some bills and obligations i need to take car of so if its not something free or something i already have it wont be done to the car right now. i have plenty of time to learn

[DTMbimmer07]

If you want upgraded valve springs check out Vac Motorsports. thats where i got 80% of my parts for my build.

[sofargone561]

if you want upgraded valve springs check out vac motorsports. Thats where i got 80% of my parts for my build.

tnank!

[euro2fast4u]

but for 300whp you wont need upgraded valve springs

[sofargone561]

but for 300whp you wont need upgraded valve springs

but like i said eventually i would like to make more so wouldn't it make more sense to build the head while i have it out and im doing other things with it?

[sofargone561]

Never mind i found the answer im looking for =) im going to keep the head relatively stock just some machine work and the upgraded rocker arms. Also im going to keep the bottom end stock like everyone else said. now what about a HG? should i buy the one from ireland racing or just replace it with a new OEM one? now its on the the ecu this will probably be the hardest part for me and the most confusing. also if i get a stand alone wich i want to do, can i get rid of the stock ecu??