Hey guys, I'm in the process of building up a 2.7 stroker and thought I would document the process for those wanting to learn how to do it as well as a cost breakdown and my learnings throughout my build. I sometimes found it a little difficult to find all the information I needed, so hopefully this can be a simplified resource for those looking to build up a 2.7i
A little bit of background on the events that led me to building a 2.7i. I bought a clean title '84 eta with a bad motor that had sat for nine years prior to buying it my senior year of high school for $250. Shortly after I bought a salvaged '89 325is that had been in a rear end collision for $950, So I did what any dumb 18 year old would do and swapped almost everything from the is into the eta shell. The only parts original to the car are the tail lights, the heater core, and the doors. I spent the next year and a half working on the car on my breaks from college, and after all that time I finally got it to run. That lasted for a week before the clutch fan went bad and the small nipple on the thermostat housing broke off. Causing me to piss coolant all over the SMOG line and overheat the motor... I had a choice to either throw new rod bearings in, swap in a new motor, or push my 2.7i build up a couple years, and I decided to send it on a stroker. With that out of the way, let's dive right in.
DISCLAIMER: This is my first time ever building an engine or even taking one apart for that matter. I am a 20 year old with his first project car, so I am learning and posting my findings here. This is meant to be a helping hand to those who are looking to build a 2.7i for the first time and to show that is a very attainable build, even to a novice.
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I plan on building the car up in stages. The end goal is to have around 200+whp n/a for a fun canyon carver/daily.
Stage 1: Barebones 2.7i with new gaskets
Stage 2: Rebuild head, deck it all the way down, adjustable cam gear, hotter cam
Stage 3: Megasquirt standalone. I want to learn how to tune, and this seems to be the best route for that
Stage 4: ITB's. Pretty self-explanatory.
Some ideas I'm currently contemplating: Seta crank, seta rods, b25 pistons with decked down block. Currently going full Seta on internals but I may switch it out later on to get better compression. Either that or custom pistons.
This initial post will go over stage one. I will be adding to this thread with each stage.
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Helpful Resources:
2.7i breakdown on R3v
https://www.r3vlimited.com/board/for...de-2-7i-how-to
DBO Seta stroker parts 1 and 2
https://www.youtube.com/watch?v=vnjm1kGQ7Wg&t=273s
M20 rebuild guide:
https://nasaspeed.news/tech/engine/bottoms-up-rebuilding-a-bmw-m20-short-block-for-your-spec-e30/
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Budgeting Based on an M20b25 Base:
Seta crank, rods, and pistons: $320 shipped courtesy of R3v member E30335i
Elring seal/gasket kits, rod bearings, main bearings, rod bolts, piston rings, and head bolts: $400
Machine shop work (head decked, tested, and cleaned. Block decked and cleaned): $250
Total: $970
NOTE: The gasket rebuild kits are optional, but most everything else is mandatory. If you want to save $100, then don't get them. But why wouldn't you spend the little bit extra to have that added layer of reliability? The hope is to never do this again, so now's the best time to replace all those seals and gaskets.
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As it stands today, I am waiting on my head and block to return from the machine shop, but I have some valuable learnings that I think a lot of novice wrenchers would benefit from. These are in no particular order, just writing what comes to mind.
1. It is not nearly as scary as you would think. If you have a seta motor already, the job is even easier than what I'm having to do. Once you get the engine out of the car and onto the stand, it comes apart a lot quicker and easier than you'd expect. It's been a really interesting experience seeing how the insides of an engine look and the M20 is a great choice for the first time engine builder. It's a very simple motor and it isn't hard to see what goes where.
2. A removable core support will make your life a lot easier for removal and installation. This is the third time I have pulled an M20 out of an E30, and the removable core support makes a world of difference. Instead of having to drop the whole front end down to just barely get the engine over and out, or unbolting the trans from under the car, you just free the engine of anything attaching it to the rest of the chassis and pull it straight out.
3. Machine shops suck. I tried to find a cost-friendly shop and I'm paying the price for it. They told me it would be done this past Tuesday, but I give them a ring on Thursday and they tell me they haven't even started it yet. I've talked to my buddies about the subject, and it seems this is pretty common for small manufacturing shops. Be prepared to wait a lot longer than you expected to get your stuff back.
4. It's going to take you a lot longer than you thought it would. Delays happen, life gets in the way, and everything you do for the first time is going to take twice as long as you expected it to. Do yourself a favor and get everything you can get ahead of time, that way you spend as little time as possible waiting for parts to show up. Don't pull the motor out of your daily and say "I'll have this done in a week." It will almost definitely take more than a week, but that's okay. Patience is a virtue.
5. Get an impact gun and a u-joint for taking stuff off. Some people are against using impacts on engine bits, but as long as you're careful and always have it on loosen, you will speed things up significantly. Impact is only used for taking things off!!!
6. Loosen the crank bolt with the power of the starter. It's torqued to 300-something nm, and while you can get it loosened on an engine stand, it is a royal pain to do so. Do yourself a favor and break the bolt free while it's in the car. There are plenty of writeups on how to do it "safely."
7. Pull out the electrics with the motor unless you absolutely can't. There are a lot of small connectors that are a pain to get to in the car, so why not make your life easier and take it off when you have more space to do so?
8. You are going to dump a ton of fluid on the ground, primarily coolant. You're going to spill a little when you undo the bottom hose on the radiator, and then you're going to spill a lot when you start undoing other things like the water pump or the heater core hoses. Just seems to be that way so be prepared to clean up a mess.
9. Spend the extra time to clean everything you can while you have more space. This is a rare opportunity you will get to clean the little nooks and crannies you would probably never even see with the motor in the car. You will thank yourself later when you go to work on the car and you have a relatively clean engine bay.
10. Research, research, research! If you don't know the answer to a problem you're having, chances are someone else had that some problem. There's so much useful information here on the forum and on youtube. All it takes is a few minutes in google and you can usually find what you're looking for.
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There are a lot of people on here who would discredit the 2.7i and call it a waste of money, saying you'd be better off to swap in an M50/M52. While those motors do produce more power, I fell in love with E30's for their mechanical simplicity and I feel that swapping in a newer engine takes away from that. There's also something to be said for messing up the weight distribution of the car, but it's probably not by a whole lot. None of this is to say that doing a swap is the wrong way to go, an M20 stroker just fit my needs/goals best. To sum up my feelings on the matter, I think the 2.7i is a budget friendly option that anyone can do to get more out of their E30 than its stock form.
With that, I am going to wrap up this initial post. As I continue to progress through my build. I'll try to keep this thread updated and add any more lessons I learn. Please keep in mind that I am a broke, 20 year old college student, so updates may be few and far between. If anyone has something they would like to add, feel free to tag in and share your experience.
A little bit of background on the events that led me to building a 2.7i. I bought a clean title '84 eta with a bad motor that had sat for nine years prior to buying it my senior year of high school for $250. Shortly after I bought a salvaged '89 325is that had been in a rear end collision for $950, So I did what any dumb 18 year old would do and swapped almost everything from the is into the eta shell. The only parts original to the car are the tail lights, the heater core, and the doors. I spent the next year and a half working on the car on my breaks from college, and after all that time I finally got it to run. That lasted for a week before the clutch fan went bad and the small nipple on the thermostat housing broke off. Causing me to piss coolant all over the SMOG line and overheat the motor... I had a choice to either throw new rod bearings in, swap in a new motor, or push my 2.7i build up a couple years, and I decided to send it on a stroker. With that out of the way, let's dive right in.
DISCLAIMER: This is my first time ever building an engine or even taking one apart for that matter. I am a 20 year old with his first project car, so I am learning and posting my findings here. This is meant to be a helping hand to those who are looking to build a 2.7i for the first time and to show that is a very attainable build, even to a novice.
------------------------------------------------------------------------------------------------------------
I plan on building the car up in stages. The end goal is to have around 200+whp n/a for a fun canyon carver/daily.
Stage 1: Barebones 2.7i with new gaskets
Stage 2: Rebuild head, deck it all the way down, adjustable cam gear, hotter cam
Stage 3: Megasquirt standalone. I want to learn how to tune, and this seems to be the best route for that
Stage 4: ITB's. Pretty self-explanatory.
Some ideas I'm currently contemplating: Seta crank, seta rods, b25 pistons with decked down block. Currently going full Seta on internals but I may switch it out later on to get better compression. Either that or custom pistons.
This initial post will go over stage one. I will be adding to this thread with each stage.
------------------------------------------------------------------------------------------------------------
Helpful Resources:
2.7i breakdown on R3v
https://www.r3vlimited.com/board/for...de-2-7i-how-to
DBO Seta stroker parts 1 and 2
https://www.youtube.com/watch?v=vnjm1kGQ7Wg&t=273s
M20 rebuild guide:
https://nasaspeed.news/tech/engine/bottoms-up-rebuilding-a-bmw-m20-short-block-for-your-spec-e30/
------------------------------------------------------------------------------------------------------------
Budgeting Based on an M20b25 Base:
Seta crank, rods, and pistons: $320 shipped courtesy of R3v member E30335i
Elring seal/gasket kits, rod bearings, main bearings, rod bolts, piston rings, and head bolts: $400
Machine shop work (head decked, tested, and cleaned. Block decked and cleaned): $250
Total: $970
NOTE: The gasket rebuild kits are optional, but most everything else is mandatory. If you want to save $100, then don't get them. But why wouldn't you spend the little bit extra to have that added layer of reliability? The hope is to never do this again, so now's the best time to replace all those seals and gaskets.
------------------------------------------------------------------------------------------------------------
As it stands today, I am waiting on my head and block to return from the machine shop, but I have some valuable learnings that I think a lot of novice wrenchers would benefit from. These are in no particular order, just writing what comes to mind.
1. It is not nearly as scary as you would think. If you have a seta motor already, the job is even easier than what I'm having to do. Once you get the engine out of the car and onto the stand, it comes apart a lot quicker and easier than you'd expect. It's been a really interesting experience seeing how the insides of an engine look and the M20 is a great choice for the first time engine builder. It's a very simple motor and it isn't hard to see what goes where.
2. A removable core support will make your life a lot easier for removal and installation. This is the third time I have pulled an M20 out of an E30, and the removable core support makes a world of difference. Instead of having to drop the whole front end down to just barely get the engine over and out, or unbolting the trans from under the car, you just free the engine of anything attaching it to the rest of the chassis and pull it straight out.
3. Machine shops suck. I tried to find a cost-friendly shop and I'm paying the price for it. They told me it would be done this past Tuesday, but I give them a ring on Thursday and they tell me they haven't even started it yet. I've talked to my buddies about the subject, and it seems this is pretty common for small manufacturing shops. Be prepared to wait a lot longer than you expected to get your stuff back.
4. It's going to take you a lot longer than you thought it would. Delays happen, life gets in the way, and everything you do for the first time is going to take twice as long as you expected it to. Do yourself a favor and get everything you can get ahead of time, that way you spend as little time as possible waiting for parts to show up. Don't pull the motor out of your daily and say "I'll have this done in a week." It will almost definitely take more than a week, but that's okay. Patience is a virtue.
5. Get an impact gun and a u-joint for taking stuff off. Some people are against using impacts on engine bits, but as long as you're careful and always have it on loosen, you will speed things up significantly. Impact is only used for taking things off!!!
6. Loosen the crank bolt with the power of the starter. It's torqued to 300-something nm, and while you can get it loosened on an engine stand, it is a royal pain to do so. Do yourself a favor and break the bolt free while it's in the car. There are plenty of writeups on how to do it "safely."
7. Pull out the electrics with the motor unless you absolutely can't. There are a lot of small connectors that are a pain to get to in the car, so why not make your life easier and take it off when you have more space to do so?
8. You are going to dump a ton of fluid on the ground, primarily coolant. You're going to spill a little when you undo the bottom hose on the radiator, and then you're going to spill a lot when you start undoing other things like the water pump or the heater core hoses. Just seems to be that way so be prepared to clean up a mess.
9. Spend the extra time to clean everything you can while you have more space. This is a rare opportunity you will get to clean the little nooks and crannies you would probably never even see with the motor in the car. You will thank yourself later when you go to work on the car and you have a relatively clean engine bay.
10. Research, research, research! If you don't know the answer to a problem you're having, chances are someone else had that some problem. There's so much useful information here on the forum and on youtube. All it takes is a few minutes in google and you can usually find what you're looking for.
------------------------------------------------------------------------------------------------------------
There are a lot of people on here who would discredit the 2.7i and call it a waste of money, saying you'd be better off to swap in an M50/M52. While those motors do produce more power, I fell in love with E30's for their mechanical simplicity and I feel that swapping in a newer engine takes away from that. There's also something to be said for messing up the weight distribution of the car, but it's probably not by a whole lot. None of this is to say that doing a swap is the wrong way to go, an M20 stroker just fit my needs/goals best. To sum up my feelings on the matter, I think the 2.7i is a budget friendly option that anyone can do to get more out of their E30 than its stock form.
With that, I am going to wrap up this initial post. As I continue to progress through my build. I'll try to keep this thread updated and add any more lessons I learn. Please keep in mind that I am a broke, 20 year old college student, so updates may be few and far between. If anyone has something they would like to add, feel free to tag in and share your experience.
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