m20b27 basic performance upgrades

[poplars]

Hey all, I've been doing a good bit of research here and weighing my options.


Currently, I have a 1984 325e (manual) that has a make-shifted 325i intake manifold (had to have a mechanic tap a vac line for the fpr...), I've had timing belt and tensioner, water pump all that done within the last year. Not sure what to do about the intake manifold other than let it be because it works?

The engine runs great, I ran a compression test a while ago and it also scored pretty nice and even on that. A little deeper inspection is probably necessary but from what I can tell the engine itself is in great shape.

The transmission: I have a transmission output seal leak, I didn't know about it when I bought the car and the transmission ran nearly dry, causing a bearing issue that I hear at around 1800 rpms, like a metal clattering noise. I also notice 1st gear doesn't accelerate as fast as I feel like it should.

So I am planning to swap the transmission for a working one, the clutch shifts nice and smooth so I feel that shouldn't be a problem for a while. My shift linkages are going out so I need to do that as well.


The ecu has a turner motorsports performance chip in it, I run 92 octane and definitely notice a performance boost. The car is also lowered with tokiko shocks and springs. Probably a bit too low, I need to look into a skid plate.


So the main thing I want input on is, what sort of performance uprgades can I do for this engine? I've read about getting better valve springs, a better rear differential, short throw shifter, performance chip call it a day sort of thing. Is that really all I can do?

I consider the 2.7i project too much for me, and a full engine swap seems like it gets more complicated than I am willing, is my plan for this car economically viable compared to a full engine swap?

[poplars]

Also I noticed the chip I have

http://www.turnermotorsport.com/p-4116-e28-528e-e30-325e-turner-motorsport-conforti-performance-chip.aspx

says it's not compatible with 1984??? What does this mean for me?

[4x4_e30]

"i" manifold on ETA head? Haha.

[TheTacoMan]

Honestly just leave, its an e motor. Its not going to be fast unless you want a turbo. 2.7i is an improvement but still not really what I consider fast.

[Bullhead]

Yeah I have done the same research as you pop and this engine was designed to be "torquey" not a high hp engine. If it has a K&N filter a good exhaust and a conforti chip your prob set. You could do a higher ratio lsd to make it quicker. I am just doing the regz with the filter, exhaust and chip. I may slap a better injector in there just because they were made more efficiently later on and this is good for mpg and a little hp boost. The best 2 ways in all my research to make these cars fast is 1) turbo it or 2)swap a M30 or 50 variant into it. I have the 52 swap or the turbo setup in my 5 year plan.

[poplars]

yeah, k&n filter is there, good exhaust, and conforti chip. only thing missing is the higher ratio lsd.

would I be better off swapping to a 325i engine? or just buying a 325i car in general?

[SkiFree]

Is this your only car? If so enjoy it for what it is for the time being. A short shifter and chip will be fine for now.

Once you've got some time/money/secondary transport then look at going with something more involved. Basically just be honest with yourself.

[whitebulat22]

I'm in a similar situation and I've decided to leave it intake / chipped / exhaust tuned until I do my full build. Stock eta is a great money saver and it's enough to slide around at least.

I saw no point long term in doing anything before a full rebuild because every build I would do with an M20 involves the 885 I head. It's a better design that BMW deemed necessary as an update, bigger ports and domed > flat combustion chambers. It's an involved swap to toss that on as you've probably seen. That alone is perfect for boost, or constructing a high compression + long stroke rotating assembly with an I head would probably push close to 200 WHP and more if you got individual throttles.

Better valve springs are only better if you're revving past 5300 rpm; this is the redline BMW gave the "super eta" because even with power to be had past there the springs may not be able to handle the job. Adding stiffer springs to an eta which doesn't have any more power to be made up there would do no good. They would just add more energy losses and sap efficiency and power.

I don't personally understand why a diff swap would be desirable on an eta unless it really falls out of it's powerband. My chipped one drops to about 2800 rpm shifting to 3rd on my 2.93 diff and takes just a small amount of time to get back to it's happy place, stock torque peaked at 3200 rpm and the chip seems to have given me more below (MarkD chip). It would be a lot of labor and a slight loss in MPG with a hotter diff but many people seem to love the results and I haven't driven one.

If anything else I'd think about a lighter clutch / flywheel. Those are always a lot of fun but it may feel a bit silly on a cruiser car like this, dashing towards it's 5300 rpm redline.

Full I motor swap and building yours would probably be about the same price because a full build would replace part of the rotating assembly on either and rebuilding the head either way. Getting a 325i seems to be expensive as those had a 4 grand premium over the lesser models when I was searching, all for a motor that would sell for 500 bucks if it was removed.

Bottom line I've decided to get other issues sorted out which will give me an eon to ponder my engine build options.

[Bullhead]

I agree, and if your ever going to do a swap try to go S50,S52 or M30 you will get a lot more bang for your buck than a 325i engine. And I wouldn't go to high on the diff ratio a 3.73 would be quick In town but on those long back roads and the interstate you would be pushing some revs I would think.

[poplars]

I'm honestly starting to consider buying a 325i in good condition.


and yes this is my only car, I'm definitely coming to the conclusion that I should leave it be and get another car or save up for an involved engine swap.

I'm definitely leaning more towards a good condition 325i, there is a lot wrong with my car and I don't think diving into it would be cheaper than buying an e30 in good condition.


what are the prices average in the pacific northwest on a 325i in good condition? are there any particular years I should strive to get?

[Bullhead]

I may be wrong on this, but the I cars made after 8/88 were updated again I believe. So 89 on would be the ticket. I live in the SE but good cars can be had down here for $3500, and that's a good rust free car that's in real good shape. If you want a real slick car that's possible had a 52 put in it right, you can get those for 6500-10k.

[Andy.B]

I have a car that began life as an eta. I drove it for several years with a chip, ka motors intake, I exhaust, and 3.25 LSD, as well as a short shifter, lowered, etc. It was a phenomenal car in that set up, and was fantastic for autocross with its great on demand torque and low speed acceleration.

I ended up doing a BimmerHeads cam'd 885/sssquid 2.7i/motronic 1.3 swap, and while I certainly gained top speed and flat out acceleration, it came at a decrease of drivability. The car screams at 3.5k-6.5k, but anything lower and it feels worse than the eta head did.

My autocross times have lowered, since I just don't have that smooth on demand torque at any rpm.

Granted, I wouldn't go back, because speed is addictive, and in a drag race my current setup would certainly outshine the eta... But a well sorted and slightly modified eta is a great car.

Remember, it was the only 6 cyl e30 for the first few years. It is by no means a bad engine just because a higher revving engine came along later. I don't understand the hate they get.

[HennaE30]

Unless your clutch is new, you might as well swap it out while you have the trans off... That's what I did.. The piece of mind that your clutch isn't gonna take a shit is worth the little bit of cash. I'd also put a new master and slave cylinder while your at it.. Again, piece of mind.


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[poplars]

aren't the clutches notoriously hard to replace? pelican tech makes it look very intimidating.

I'm seeing pristine 325i's for around 4k, I rhink thats the direction I"m going to go, then if I ever want to do anything more with this car I'll have another car to drive around, or vise versa.

[Bullhead]

aren't the clutches notoriously hard to replace? pelican tech makes it look very intimidating.

I'm seeing pristine 325i's for around 4k, I rhink thats the direction I"m going to go, then if I ever want to do anything more with this car I'll have another car to drive around, or vise versa.

No sir they are not, I just did a tranny swap in 2 days and I wasn't full bore either. The worst part is the "bitch clip" and the top starter bolt can sometimes have a nut and not threaded. But they aren't real bad. I accomplished it solo but a team can knock it out in a day no prob. A cheap diy for when you drop the tranny down is 2 get the input and output shaft seal, they are like $6 and a good investment to keep spots off the ole driveway. Oh and one more thing, you don't have to actually take the bitch clip off. I just unbolted the rear shifter assembly and let it drop down.