The One That Didn't Get Away [100K Mile E30 325is]
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The non-optimized 3.1 L M20 w/ 288 cams I had some seat time with was every bit as good as an S52 swap but with more character and top end pull.
As you already know, its very cost-prohibitive but overall probably about the same amount of cost and effort as a properly done S52 swap.
M20’s are easy.
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My plan is to get this motor refreshed so that it’s in good operational order for the time being. But I would like to do a mild striker build down the road. I know the cost to performance is not great, but an M20 with a little more punch and grunt would be fun.
Also, this:
I realize this is a fully built motor, sounds amazing though.
Yum, that drive by reminds me of standing on the hill before turn 5 at RA.
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The non-optimized 3.1 L M20 w/ 288 cams I had some seat time with was every bit as good as an S52 swap but with more character and top end pull.
As you already know, its very cost-prohibitive but overall probably about the same amount of cost and effort as a properly done S52 swap.
M20’s are easy.
What is needed for a 3.1? I've really only seen 2.7 and 2.9 examples.
Yum, that drive by reminds me of standing on the hill before turn 5 at RA.
It's because of the T R E E S.
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With a car as clean and low mileage as yours I'd definitely be inclined to keep the original engine. There is absolutely no shame in liking an M20, they're pretty hard to hate! I'd love one to play around with again at some point.
I totally agree that M20's (and the M30) are some of the best sounding BMW engines too, anything newer has absolutely nothing on them.
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With a car as clean and low mileage as yours I'd definitely be inclined to keep the original engine. There is absolutely no shame in liking an M20, they're pretty hard to hate! I'd love one to play around with again at some point.
I totally agree that M20's (and the M30) are some of the best sounding BMW engines too, anything newer has absolutely nothing on them.
This is the plan for the foreseeable future. My only plans for it are maintenance and an exhaust.
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I know most people would opt for a different motor than the M20, but I’ve really been enjoying it. Really great for the casual cruising and still comes alive above 5k. I also have the weird dichotomy of loving fast cars, but don't really have the need for speed much.
That's exactly why I decided to spend money on refreshing the M20 rather than doing a swap. IMO, the amount of power is perfect. You can give it the beans and have a ton of fun on the backroads while not overly exceeding the speed limit. When I had my "stage 2" S60R it was too easy to go too fast. And at the end of the day, what was the point of it? In that second it was a lot of fun, but what I could have done to myself (with 3 kids) or someone else wasn't worth it. I sold it shortly after having that revelation.
Rebuilding my m20 gave me a lot of respect for the engine and its place in the car.
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That's exactly why I decided to spend money on refreshing the M20 rather than doing a swap. IMO, the amount of power is perfect. You can give it the beans and have a ton of fun on the backroads while not overly exceeding the speed limit. When I had my "stage 2" S60R it was too easy to go too fast. And at the end of the day, what was the point of it? In that second it was a lot of fun, but what I could have done to myself (with 3 kids) or someone else wasn't worth it. I sold it shortly after having that revelation.
Rebuilding my m20 gave me a lot of respect for the engine and its place in the car.
I'm going to be doing a lot of reviewing your thread down the road.
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What is needed for a 3.1? I've really only seen 2.7 and 2.9 examples.
https://www.iemotorsport.com/product/ie-3-1l-stroker-kit-m20/
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https://www.iemotorsport.com/product/ie-3-1l-stroker-kit-m20/
Yellow text on a white background is horrid.
That being said, this is very interesting. I see they suggest a WAR chip or running MS in addition to bigger injectors. If the WAR chip is an acceptable ECU tune, that would be prefer over going complete stand alone.
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WAR chip is acceptable on an OBD1 E36, but junk on an E30. The MAF conversion is very problematic. MS2 plug and play is just fine. Get it setup correctly and a dyno tune and you shouldnt have to touch it anymore and have a much better diagnostic and logging ability. The drivability and throttle response improvement are worth it alone on a stock M20
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WAR chip is acceptable on an OBD1 E36, but junk on an E30. The MAF conversion is very problematic. MS2 plug and play is just fine. Get it setup correctly and a dyno tune and you shouldnt have to touch it anymore and have a much better diagnostic and logging ability. The drivability and throttle response improvement are worth it alone on a stock M20
The war chip is junk in general. Don't bother.
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My vote is MS2 pnp. Not sure if they made an MS3 pnp for the m20?
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Here is how it will play out: you grab a bimmerheads ported and polished rebuilt head with a cam, attach some ceramic coated headers while you are at it, Drop that in sometime in June. then work on a stroker bottom end build and preparing for MS2 over the winter.
i kno, rite?
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Orrrrrrrr, k24 swap it & add cams. Better weight balance, more power, wasn’t brought to the US on the mayflower, etc.
reading this for 245hp makes my wallet cry
/roastme
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reading this for 245hp makes my wallet cry
/roastme
245hp at the crank after playing with the smoothing and correction factors, deleting the lot of 237bhp plots that preceeded it and dry-icing the intake.
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Orrrrrrrr, k24 swap it & add cams. Better weight balance, more power, wasn’t brought to the US on the mayflower, etc.
reading this for 245hp makes my wallet cry
/roastme
I honestly wonder what the cost difference would really be between building the M20 already in your car vs swapping a K24. The adapter plate is like $1500 alone.
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Oil pump location on the K motor is right in the middle of the subframe on an e21/e30. Not that it can't be done, but it's not pretty and there is some fabrication involved.
Luckily kmiata exists and takes the headache out of the swap. The e30 k swap is much simpler than the Miata k swap.
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