320i/323i Intake differences

[Justlikemusic 0]

I have bought an '86 325e four door, 5 speed, and have access to a 320i motor and gearbox for like $350, or another person selling a 323i engine for $500 (Australian dollars)

I have read everywhere about the 325i heads and that the manifolds and TB are good to put on the 325e's.

I can't really purchase a motor since I have nowhere to sit it for now.

So far I have cleaned it up a bit. I have some 205/65/15" tyres that will go on some rims too.

Then differential gears changed would be good also. 3.73:1 will really improve the cars driving. I only do 60km/h to work, and when I'm doing 100km/h or so its not for very long... either dragging in the 60 zones, or 10 minutes max to mate's places.

However here is my main question. I would like to initially do the following mod:

* Larger intake manifold and TB...

Need info on 320i and 323i differences. It's hard to find the 325i stuff around West Australia, and I'll be happy to get a larger MFD/TB even if its slightly smaller for cheap. Plus my injectors are noisy and rubbish, and I want to paint the intake manifold to make it look a little nicer.

[will 169]

You are likely to have a small port head on the 325e motor so I don't know how much benefit you will get from changing the manifold/TB/afm, best check what inlet port size you have first. Bolting a large port manifold onto a small port head will just cause flow problems and you might end up worse off than with the standard manifold etc. This conversion is normally done as a complete head/intake manifold/TB/AFM/exh manifold swap for it to work efficiently.

The 325e motor should be better than the 320 motor from a power perspective and also will be far more fuel efficient. Not a swap I would consider.

The 323 motor will be a better swap for the 325e motor, but it will also have less power than the 325e motor but will rev quicker and be more responsive than the 325e motor. Again I think I would stick with the 325e motor and put my funds towards a complete head swap or a 325i motor complete.

The 325e probably has a 'long' diff, check what ratio it has and then possibly swap it for a 'shorter' ratio, this will give you a lot more get up and go from pulloff and while cruising, but don't make a radical change to the ratio though or you will just ruin the cruising and fuel economy.

Will

[Justlikemusic 0]

Ahhh... so really I need the full 323i top end if I want to do anything. Or the 325i top end if I want turbo and cheap way of lowering the compression without touching the bottom end. The car has nearly 300,000km's on it, but it has been well looked after by the female owner I bought it from.

The problem with the beema engines is that most of the stuff is really expensive. I can get a "1988 BMW E34 M5 ENGINE (S38B36)" with bent valves for $3000. That has been the best thing I've seen so far. Its like 220kw or something like that, stock. But to rebuild the thing... then it will probably need new pistons and all sorts, I dunno, havent seen it. Otherwise, the S14 motor and other options are really expensive, but I guess thats what you get when owning a prestige vehicle lol.

Ow, "The head is off motor as it has bent valves"

Edited February 11, 2008 by Justlikemusic

[will 169]

You need to be really careful when considering a head swap as the various motors have different piston crowns which will only work with a specific head.

Will

[Justlikemusic 0]

Welcome Nathan, enjoy your stay.

Nice e30, I look forward to seeing what you decide.

Ok Will, Ill make a note of that. For that info as far as head swaps go I can search. I got an 86 325e so I think thats the 'earlier' e30 eta engine. I dont feel confident in doing a head swap with a OHC engine... as I mostly have worked on V8's, and gotten the bottom end done by shops. What I might do though is fix a cold air intake into the car, and source another diff.

Im currently trying to cruise in 60km/h zones and have to keep it in fourth. If I drastically up the ratio, then I should be able to cruise in fifth, and I dont care about economy so much, engine longevity is probably higher on the list. Doing 2200rpm or so (i forgot, i just bought the car) at 100km/h is ok, and Id tolerate 2800rpm at 100km/h if need be. I normally just do 70m/h driving max.

The thing with the eta though, is that I can drastically feel that it wants to breathe. The exhaust system looks pretty good for a stock vehicle. Twin pipes to cat then relatively decent out from there. Could I just swap the TB to a larger unit and port the stock intake manifold out if need be? Also, I wouldn't mind knowing what is needed to be done to the factory ecu if anything to accomodate the different TB.