Engine swap: what choice of (recent) engine?

[bosun73]

Hi All,

First of all, my apologies if this has been discussed a million times before, and feel free to point me towards previous discussion threads...

I am the proud owner of a 1989 325i, it's my daily driver, and loads of fun to drive. But it's got over 337,000km on the clock. Although I don't have any major problems with it at the moment (touch wood), I can imagine that one day it might, and something will go wrong that will simply be silly money to get repaired.

So, I am considering an engine swap in the not-too-distant future. However, searching the internet, including the E30 zone, all the engine swaps that have been written about and described thus far are for engines that are now becoming quite old themselves...

Therefore, my question is which engine swaps are there that use relatively recent engines? (By that I mean in the last 10 years or so). And of these, which are more "straight-forward" to do, and which have been done a bunch of times? Just for info, I'm not looking for a "high performance" engine, but something that delivers a little more oomph than I am currently getting would be nice. Also, both BMW and non-BMW engines can be suggested... The only stipulation is that the donor cars need to be fairly easy to get hold of.

(I've seen the bloke on youtube that has put a Tesla engine into an E30, but going electric is not really my thing...)

Thanks.

[flybynite]

Just keep the 325i M20B25. Nothing that cannot be fixed on that engine, still plenty of bits around. Will be cheapest and least bother in the short term, keeps the M20 sound and your car will be worth more in the end.

[reggid]

you are worried an engine with no real problems (other than high mileage) might get expensive to fix so you think that swapping in a more modern engine that is almost certain to cost more than a m20 rebuild (one of simplest engines ever made) is the most cost effective solution?

On a serious note wait until there is a problem and do a 2.8/2.9L m20 build its only a small differential over a stock rebuild but will produce some nice power and torque gains and should make 200/200

[bosun73]

you are worried an engine with no real problems (other than high mileage) might get expensive to fix so you think that swapping in a more modern engine that is almost certain to cost more than a m20 rebuild (one of simplest engines ever made) is the most cost effective solution?

On a serious note wait until there is a problem and do a 2.8/2.9L m20 build its only a small differential over a stock rebuild but will produce some nice power and torque gains and should make 200/200

Hi, and thanks. Of course when you put it like that, it does sound kind of ridiculous! In any case, it's not something I am planning to do in the near future, and I may end up not doing it at all.

I suppose that my question was more of a general interest question, rather than a technical question: I am just interested to know which recent engines are a good fit, and not too complicated, swap into an E30, as there doesn't seem to be an up-to-date discussion on the choices available.

Thanks again.

[reggid]

The n52b30 would be a great engine for an e30 though it’s not as straight forward as the m54 and m52 but it’s leaps and bounds ahead. I’m sure there will be some off the shelf solutions in the next couple years

[flybynite]

I suppose that my question was more of a general interest question, rather than a technical question: I am just interested to know which recent engines are a good fit, and not too complicated, swap into an E30, as there doesn't seem to be an up-to-date discussion on the choices available.

The problem is anything past the M52 era has the added issue of all the emissions paraphernalia and the newer the engine the more it has. That makes it all the more difficult to get it running in an older and smaller shell. The engines are run with ever more integration into the car sensors that need either transplanting into the E30 or coding out on the ECU for the new engine to run correctly. There is nothing new that is "not too complicated".

As you say the existing swap candidates are getting old themselves and the benefit over the original engines gets less as time goes on. Factor in originality and car value and it makes even less sense.

As above a properly done 2.9 makes a good engine out of a worn 2.5 and is tried and tested.

Modern engines have been fitted, like N54 etc and Non BMW engines like LS and K24 but they become a matter of time and money, enough of both then anything is possible.

[bosun73]

I suppose that my question was more of a general interest question, rather than a technical question: I am just interested to know which recent engines are a good fit, and not too complicated, swap into an E30, as there doesn't seem to be an up-to-date discussion on the choices available.

The problem is anything past the M52 era has the added issue of all the emissions paraphernalia and the newer the engine the more it has. That makes it all the more difficult to get it running in an older and smaller shell. The engines are run with ever more integration into the car sensors that need either transplanting into the E30 or coding out on the ECU for the new engine to run correctly. There is nothing new that is "not too complicated".

As you say the existing swap candidates are getting old themselves and the benefit over the original engines gets less as time goes on. Factor in originality and car value and it makes even less sense.

As above a properly done 2.9 makes a good engine out of a worn 2.5 and is tried and tested.

Modern engines have been fitted, like N54 etc and Non BMW engines like LS and K24 but they become a matter of time and money, enough of both then anything is possible.

I fully understand your point that absolutely any engine can be made to fit inside an E30 if you throw enough money and time at it... which is why I'm asking that of the swaps that have been done before, which of these are the more straightforward ones?

I hadn't really considered that most of the electronics from modern engines would need to be made redundant somehow before swapping them in... I guess that this in itself would make many of the swaps less attractive propositions, or unfeasible.

You end by saying that "Modern engines have been fitted"... and this is exactly the thing that I am asking. So far, the list is quite short (N52 and N54, and non-BMW LS and K24). Are there others (that have been successfully swapped)?

[onthames]

M88 maybe!

[flybynite]

You end by saying that "Modern engines have been fitted"... and this is exactly the thing that I am asking. So far, the list is quite short (N52 and N54, and non-BMW LS and K24). Are there others (that have been successfully swapped)?

Although I said they had been fitted, personally I have not seen one that I would consider as "successfully swapped" Most never get past the 'work in progress' stage with compromises in finish, reliability, how they drive or a long list of bespoke parts compared to a well sorted original. For even the easiest of swaps the issues and cost outweigh what it takes to get the M20B25 back running well.

[bosun73]

You end by saying that "Modern engines have been fitted"... and this is exactly the thing that I am asking. So far, the list is quite short (N52 and N54, and non-BMW LS and K24). Are there others (that have been successfully swapped)?

Although I said they had been fitted, personally I have not seen one that I would consider as "successfully swapped" Most never get past the 'work in progress' stage with compromises in finish, reliability, how they drive or a long list of bespoke parts compared to a well sorted original. For even the easiest of swaps the issues and cost outweigh what it takes to get the M20B25 back running well.

It looks like you're not a huge fan of swaps, which I can kind of understand.

I, myself, am a complete newbie: this is my first E30 (had it 4 years now), and I've never been in anything that's been swapped. Mine is still completely original, and I love how it drives and handles. So I can appreciate that there is still something to be cherished about an original version...

Still, it's an interesting discussion to be had, about the ease of swapping of more recent engines, even if suitable candidates are few...

[Blanca]

Nothing after1995 is any good, made to last 12 years, tops.

[flybynite]

It looks like you're not a huge fan of swaps, which I can kind of understand.

Far from it I have a 325i with no engine as it was used for another car. I have an E46 330i that is a perfect donor if I go that way. If there was a better option I would do it. For me it has to be N/A straight 6, BMW origin and no heavier than the M20.

More recently there have been parts spring up for the M20 (like the 2.9 piston) it makes the bother of swapping (or developing custom made parts) for swaps less common.

Most of the money now is in keeping the car as close to original and that is where most parts are.

I, myself, am a complete newbie: this is my first E30 (had it 4 years now), and I've never been in anything that's been swapped. Mine is still completely original, and I love how it drives and handles. So I can appreciate that there is still something to be cherished about an original version...
Still, it's an interesting discussion to be had, about the ease of swapping of more recent engines, even if suitable candidates are few...

An engine that shared a car with an M20 has advantages of OEM parts to swap. The last one of those was the M52, parts coming from 5 and 7 series. M54 is similar enough to benefit from most of those parts.

Everything later will need the sump/oil system hacked to clear the e30 subframe or subframe hacking to take the new sump. Most often both. Not a fan of that myself unless done properly and not seen one yet that was.

Modern turbo engines would have to be run on a severely re-programmed ECU or more likely a stanadalone like a Megasquirt. Either way a lot of time and money and getting further away from what an E30 is.

[flybynite]

M88 maybe!

Nice engine, one of my favourite but not in an E30. I already have a boat-anchor I could swap in if I wanted to.

Personal view but don't see the point in swapping in a lump that destroys how it goes round corners. I know I'm in the minority given what is on the FaceAche pages these days. Clearing a kerb seems optional.

Now something built along the lines of an M12, that would fit well!

[DanThe]

The n52b30 would be a great engine for an e30 though it’s not as straight forward as the m54 and m52 but it’s leaps and bounds ahead. I’m sure there will be some off the shelf solutions in the next couple years

This is one of the most interesting engine conversions to me just lately, they are great as they are, 260 odd hp standard, easily 280hp or so with an exhaust/tune, get rid of the EGR nonsense and its a lightweight lump of happiness

[bosun73]

The n52b30 would be a great engine for an e30 though it’s not as straight forward as the m54 and m52 but it’s leaps and bounds ahead. I’m sure there will be some off the shelf solutions in the next couple years

This is one of the most interesting engine conversions to me just lately, they are great as they are, 260 odd hp standard, easily 280hp or so with an exhaust/tune, get rid of the EGR nonsense and its a lightweight lump of happiness

Are these conversions (the N52) being attempted more often now? Would you say that they are becoming more straightforward to do now, or still a big faff?

And what are they like to actually drive? This is probably the most important consideration...

[reggid]

I think issue is the sump and subframe tequires some custom stuff though not been following closely as I’m not a swap kind of person . A few people on r3v limited have done it.

[flybynite]

Are these conversions (the N52) being attempted more often now? Would you say that they are becoming more straightforward to do now, or still a big faff?

Have a read through this and see if you think it is worth it over a nicely running 2.9 M20 where everything fits as it should

https://www.r3vlimited.com/board/forum/ ... 2%A0/page3

And what are they like to actually drive? This is probably the most important consideration...

Will all depend on how much butchery is done to the subframe and how up with steering angles the person doing said butchery is. Lift the bonnet and it looks good, it may drive but look closer and you have things like this:

(another N52 swap courtesy of R3V)

[Blanca]

KISS, nuff' said.

I had to look under the bonnet of a X5 yesterday, (none starter) and I wouldn't put that plastic covered crap in my E30, the M20B20 is fine and does just what I need, a sweet, smooth trouble free ride all day long and easy to service.-

[martauto]

(another N52 swap courtesy of R3V)



Mart.

[bosun73]

KISS, nuff' said.

I had to look under the bonnet of a X5 yesterday, (none starter) and I wouldn't put that plastic covered crap in my E30, the M20B20 is fine and does just what I need, a sweet, smooth trouble free ride all day long and easy to service.-

Indeed! There is much to be said for keeping things simple... And that seems to be the general consensus here! So in that case, I am happy to accept that some things are better left untampered with (or only slightlytampered with).

Having said that, I'm surprised that not more pro-swappers have added their 2 pennies worth on this topic...

[Be30]

Imo, BMW dont make any engine that is truly suitable for the e30 (minus the s14)
The four cylinders are asthmatic unless you plough thousands into an m42
The six cylinders hang too far over the front axle and generally weigh too much.
V8s are the same and drink too much fuel

[DanThe]

Having said that, I'm surprised that not more pro-swappers have added their 2 pennies worth on this topic...

They are busy with engine conversions taking over their lives

You may have noticed hardly anyone posts on here, thats why they are not replying.

If you want reliability then you leave an engine in standard form, it will always last longer. If you want to get another 100hp out of an M20 its not as simple as ording a few custom parts off the net and a weekend in your garage, far from it! The same goes for an engine conversion, I have a customer that is well into 20k on an M20 3.2 after several fuckups by a so called 'specialist'

Either route can cost fortunes and leave you without a useable car for months/years if you dont make the right decision

[flybynite]

Personally I would put getting 100bhp extra from an N/A engine in the same category as swapping from a modern canbus car, It is a different calibre of time, skill or money required.

But if you have a very high-mile 325 (like the OP) with a generally worn engine maybe needing re-bore and new oversize pistons, maybe regrind on crank and cam then a 2.9 could be built with off-the shelf parts for comparatively little extra cost. It would get about +30 or 40bhp, more torque and I would say would be just as reliable.

Bang for buck, I would build one of those without hesitation, but for the fact I have a low-mile FL E46 330i sat here that I have owned and driven for a while now and know well.

It is the latest and lightest engine that will pretty much bolt-in using the OEM BMW parts bin. More power and torque than is easily had from an M20 or S14 and if looked after can achieve moon miles (like the one I sold 10 years ago with 270K)

Only other engine that I think would be more suitable is an Eaton-supercharged M44 or a KKK turbo M10 on carbs, but that is well in first category of time/skill/money.

What you do for an engine comes down very specifically to what you want to achieve and why. That can often be the hardest question to answer and a lot of money can get washed down the drain in the process.

[bosun73]

Thanks for the great replies!

I think it all depends where you would place yourself on the scale: "Bad boy" to "Purist"... AND how much money you are willing to spend. As for me, I'm not really looking for silly amounts of hp (maybe just a slight increase to what's there already) and I wouldn't ever dream of spending £20k + to make ANYTHING "a little bit faster"!!

Flybynite, I find myself agreeing with you! (particularly your very first reply).

Just to clarify though, your E46 330i engine, that's an M54B30, correct? And you're saying that these swap into an E30 quite nicely, is that right? Thanks.

[flybynite]

Just to clarify though, your E46 330i engine, that's an M54B30, correct? And you're saying that these swap into an E30 quite nicely, is that right? Thanks.

Yes M54B30. There are a couple of in-depth swap guides on R3V, It is not the right engine if you want a high-revving machine or want to get more power out of it. That engine is best used as-is, make the most of the torque from vanos and disa and leave it alone.

Still a lot of work/time/money but fewest fabricated parts to make/find/buy compared to ANYTHING later

If you want high-revving power then you are best with an M50/52 and many on here will say they are the best choice anyway and in many ways they are right.

If the car still had its M20 engine and I did not have a defunct 330i sat here with a good engine, I would rebuild it as a 2.9 no question, I still may source a dog of a B25 engine and do it anyway

[bosun73]

Thanks for all the info! It's been v useful.

[martauto]

I have had two e46 330 coupes and they are a cracking engine likewise my M54B25 I am driving now but I would still have the 330.
Put into an e30 ? WOW

Mart.

[DanThe]

a 2.9 no question, I still may source a dog of a B25 engine and do it anyway

I seriously think you need to get crcking with this, you have been on about it for years

[flybynite]

a 2.9 no question, I still may source a dog of a B25 engine and do it anyway

I seriously think you need to get crcking with this, you have been on about it for years

Nah you are getting confused Dan must be old age The M20 I am building is going in the 323i chromie and it is 2.7 not 2.9. Can't put a 2.9 in a chromie C1 !!!! not the done thing Almost as bad as CR24v . That is where said M20B25 went from the 325 and deserving cause it will be when done (it is being done as we speak but everything is slow now)

Gaping hole under the facelift 325 bonnet is what I can't make my mind up about. heart says 325i should have an M20, leave swaps for 316s. Head says M54B30, six speed, torsen LSD Mk60 ABS etc etc done REALLY well would be a good car. Not a matching-numbers car to start with so no great loss.

I have all the parts, just need you to build me a proper mandrel-bent exhaust

If I build another M20 for that I have to find another donor engine and loom, another good 885, another set of custom pistons, rebore & balance, get another BTB3 and end result won't be that different to the 2.7 in the chromie. Fitting the plastic engine I have here already seems easier.

Thinking time is never wasted ! 4 other cars to do first and barely on No2