BMW E30 K20 Swap
Discussion
BMW E30 K20 build – 100% ordinary
This swap has been done countless times in the past, there is literally nothing ground-breaking about this build, it’s not going to be 1,000hp, it’s not going to be the fastest car to ever set alight the strip, nor will it feature scene wheels or stanced alignment, massive body kits or stupid aero, functionality and OEM levels of quality, fitment and driveability are the name of the game, and learning a whole ton in the process. Honestly, once I get fixated on something, there is literally never enough time in the world to spend researching and finding out everything there is to know about the subject. Doing a project like this gives me absolutely tons of related subjects to research into and I am having a blast doing it!
So the intention is to combine a few of my favourite things, the E30 with an iconic 4 cylinder engine; the Honda K20. It doesn’t need to the fastest thing going, it just needs to sound bloody good! All we need here is a quiet exhaust and an open cone filter for the induction noise. Job done.
My donor car is a recent acquisition, I’ve been keeping an eye out for something as low mileage as possible and came across this 51k mileage 316 auto, the least desirable spec of powertrain but to be honest its been quite a pleasure to waft around in something smooth and quiet, and most of all, not diesel!
For the gearbox I am going with the S2000 box, not only to keep it in the same family, but it is also arguably one of the nicest RWD gearboxes I’ve ever used. For a 6 speed it is also quite light weight and helping to keep the weight increase down to a minimum. Before I had the car I had bought a gearbox off of eBay and began scanning it in, the first ever part to arrive was the adapter plate followed very much later by an incorrectly machined flywheel… doh! We're still in the process of getting this sorted out but hopefully have a finished flywheel in the new year that we can start testing.
For the engine, I am trying to keep it is a minimalist as possible, and will be using one of our own electric water plate kits with a Pierburg electric water pump, this really cleans up the accessory side of the K20.
The next item I am working on is a billet RWD sump, unfortunately the pickup sits where the cross member otherwise sits, and so the plan is to pretty much replicate the OE BMW forward facing sump. I ordered up a brand new K20 oil pump and scanned this in and fitted it up to the engine ready to design a pickup. Rough mock-up of positioning can be seen in the image below and it also shows how space we have to play with. Until I scan the engine bay in and position the engine I won’t know for sure.
Updates to follow…
This swap has been done countless times in the past, there is literally nothing ground-breaking about this build, it’s not going to be 1,000hp, it’s not going to be the fastest car to ever set alight the strip, nor will it feature scene wheels or stanced alignment, massive body kits or stupid aero, functionality and OEM levels of quality, fitment and driveability are the name of the game, and learning a whole ton in the process. Honestly, once I get fixated on something, there is literally never enough time in the world to spend researching and finding out everything there is to know about the subject. Doing a project like this gives me absolutely tons of related subjects to research into and I am having a blast doing it!
So the intention is to combine a few of my favourite things, the E30 with an iconic 4 cylinder engine; the Honda K20. It doesn’t need to the fastest thing going, it just needs to sound bloody good! All we need here is a quiet exhaust and an open cone filter for the induction noise. Job done.
My donor car is a recent acquisition, I’ve been keeping an eye out for something as low mileage as possible and came across this 51k mileage 316 auto, the least desirable spec of powertrain but to be honest its been quite a pleasure to waft around in something smooth and quiet, and most of all, not diesel!
For the gearbox I am going with the S2000 box, not only to keep it in the same family, but it is also arguably one of the nicest RWD gearboxes I’ve ever used. For a 6 speed it is also quite light weight and helping to keep the weight increase down to a minimum. Before I had the car I had bought a gearbox off of eBay and began scanning it in, the first ever part to arrive was the adapter plate followed very much later by an incorrectly machined flywheel… doh! We're still in the process of getting this sorted out but hopefully have a finished flywheel in the new year that we can start testing.
For the engine, I am trying to keep it is a minimalist as possible, and will be using one of our own electric water plate kits with a Pierburg electric water pump, this really cleans up the accessory side of the K20.
The next item I am working on is a billet RWD sump, unfortunately the pickup sits where the cross member otherwise sits, and so the plan is to pretty much replicate the OE BMW forward facing sump. I ordered up a brand new K20 oil pump and scanned this in and fitted it up to the engine ready to design a pickup. Rough mock-up of positioning can be seen in the image below and it also shows how space we have to play with. Until I scan the engine bay in and position the engine I won’t know for sure.
Updates to follow…
Austin_Metro said:
What sort of power will you get with that?
With a few tweaks about 240-260hp n/a, however with the stock S2000 diff I plan to install and smaller rolling radius tyres the effect will be like a lower final drive. I don't want crazy power in this car as it will be scary, the plan is about 250hp/ per ton, and close ratios 
Mudgey said:
Austin_Metro said:
What sort of power will you get with that?
With a few tweaks about 240-260hp n/a, however with the stock S2000 diff I plan to install and smaller rolling radius tyres the effect will be like a lower final drive. I don't want crazy power in this car as it will be scary, the plan is about 250hp/ per ton, and close ratios B'stard Child said:
I'm not up on Honda Engines but why a K20? surely the S2000 engine and box would have negated the need for an adaptor plate and flywheel mods - it's 240 bhp isn't it out of the box?
Interested in what is so special about a K20
Also curious about this. Electric water pump looks cool, what are the advantages there? Other than a good bit neater?Interested in what is so special about a K20
Jhonno said:
300bhp is a nice number in these.. My old S50B30 E30 was nice at that number. Could have taken a bit more.
I've not driven one with that amount of power, the most is my old 1.8 litre with about 110hp about 15 years ago that I sold for £300!! Imagine what £300 buys you in the E30 world these days..... hahahaB'stard Child said:
I'm not up on Honda Engines but why a K20? surely the S2000 engine and box would have negated the need for an adaptor plate and flywheel mods - it's 240 bhp isn't it out of the box?
Interested in what is so special about a K20
Well Sir, the K20 is arguably the best 4 cylinder anyone has ever made, the reputation is a product of the low cost accessibility afforded to it from mass manufacture, the Japanese reliability, and an aftermarket that has sprung up to support the engine and pushed the platform to the lofty heights we see today. Perhaps the right engine at the right time? I think it is the perfect balance of accessibility and cost to obtain serious power.Interested in what is so special about a K20
I am undertaking this build to showcase the level of quality and detail that we put into the parts that we provide for this platform and would like to show this car off at shows and events. My absolute passion is R&D, learning, designing, and testing and I have been fortunate to build a business doing so, I don't want to use this as a plug for my business at all but my day job is not doing dissimilar to what we see in this thread. In one sense this shows what we can do as a business, but also it's something we are extremely passionate about and I couldn't imagine doing anything else! This is THE thing I live for!
Edited by Mudgey on Wednesday 28th December 22:03
Mudgey said:
B'stard Child said:
I'm not up on Honda Engines but why a K20? surely the S2000 engine and box would have negated the need for an adaptor plate and flywheel mods - it's 240 bhp isn't it out of the box?
Interested in what is so special about a K20
Well Sir, the K20 is arguably the best 4 cylinder anyone has ever made, the reputation is a product of the low cost accessibility afforded to it from mass manufacture, the Japanese reliability, and an aftermarket that has sprung up to support the engine and pushed the platform to the lofty heights we see today. Perhaps the right engine at the right time? I think it is the perfect balance of accessibility and cost to obtain serious power.Interested in what is so special about a K20
I am undertaking this build to showcase the level of quality and detail that we put into the parts that we provide for this platform and would like to show this car off at shows and events. My absolute passion is R&D, learning, designing, and testing and I have been fortunate to build a business doing so, I don't want to use this as a plug for my business at all but my day job is not doing dissimilar to what we see in this thread. In one sense this shows what we can do as a business, but also it's something we are extremely passionate about and I couldn't imagine doing anything else! This is THE thing I live for!
Edited by Mudgey on Wednesday 28th December 22:03
I have fond memories of seeing an MG midget absolutely smash all timings set on a sprint event - it had been fitted with an S2000 engine and box - rapid and sketchy as f
k doesn't come close to describing it The E30 you have found looks like a great example to start with - right number of doors too
shalmaneser said:
Also curious about this. Electric water pump looks cool, what are the advantages there? Other than a good bit neater?
Oh yea, a hell of a lot neater! I am going to be using a Pierburg CWA200 for this build with PWM control, this will allow the programming of flow vs temperature instead of flow vs engine speed as they are mechanically driven. The downside is cost, most manufacturers opt for mechanical pumps due to the fact they are significantly cheaper.B'stard Child said:
Ahhh OK so in a nutshell you already know everything you need to do to the K20 (based on experience)
I have fond memories of seeing an MG midget absolutely smash all timings set on a sprint event - it had been fitted with an S2000 engine and box - rapid and sketchy as fk doesn't come close to describing it
The E30 you have found looks like a great example to start with - right number of doors too
It is a great starting point, however has owned it previously has looked after it and am greatly appreciative! The bodywork has less rust and dents that my 2014 daily driver! You could say it is a perfect starting point, I won't be needing to treat much rust or repair much, that is for sure I have fond memories of seeing an MG midget absolutely smash all timings set on a sprint event - it had been fitted with an S2000 engine and box - rapid and sketchy as f
k doesn't come close to describing it The E30 you have found looks like a great example to start with - right number of doors too
As a serial BMW owner I'm a bit sad to see a Honda engine getting fitted to an E30, but anything has to be better than a 316i Auto!
But if you fit a Pierburg electric water pump make sure you can monitor water temperature. I've had 4 BMWs with those pumps and when they die overheating happens in a couple of minutes.
But if you fit a Pierburg electric water pump make sure you can monitor water temperature. I've had 4 BMWs with those pumps and when they die overheating happens in a couple of minutes.
Mudgey said:
Jhonno said:
300bhp is a nice number in these.. My old S50B30 E30 was nice at that number. Could have taken a bit more.
I've not driven one with that amount of power, the most is my old 1.8 litre with about 110hp about 15 years ago that I sold for £300!! Imagine what £300 buys you in the E30 world these days..... hahahaOver the past couple of days we have managed to get a good few hours in on this project, we have got the engine out, the engine bay and chassis dotted up with targets, a quick laser scan at a low resolution, and then a quick alignment in CAD to see whether we can indeed fit the K20 engine with S2000 box in place of the original engine. Straight off it looks like we may have to angle the engine up at the front a little to get some extra sump clearance, and also the gear stick end down. The next step is to start scanning in the subframes so we can check engine clearance here. More to follow!
We use a metrology grade Handyscan 700 made by Creaform, it has incredible accuracy and detail, they also develop a fantastic suite of software for use with the scan data, this allows you to extract all the information needed for reverse engineering such as hole positions, surfaces, extrusions, profiles etc which can then be imported into CAD. Consumer stuff is at that point where it looks good in photo's but is not really accurate or high enough quality for reverse engineering or at least the things that we get involved with.
They are incredible tools and we wouldn't attempt half the CAD & Engineering jobs we get without one!
They are incredible tools and we wouldn't attempt half the CAD & Engineering jobs we get without one!
So a couple of minor updates over the past week or so, and unfortunately a couple of snags, but then it wouldn’t be a good project without some spanners thrown in the works for good measures now would it!
We have scanned in an S2000 header and also the E30 steering rack and cross member. The first issue thrown up is with the steering UJ clearance for the exhaust and the rack pinion area that sits so close to the K20 engine. The original BMW engines seem to be far narrower at the bottom of the block than our K20 does and so have ample room. We may be able to raise the engine but atm we don’t know how high we can move the engine before we run into bonnet clearance issues. Currently the crank position is roughly the same as OEM. Next we need to scan the bonnet and then position it in CAD to get an idea on how much height we have to play with. Another potential issue is keeping prop shaft angle straight and not knowing how far of an angle we can get away with without causing vibration issues. Loads to look into but this is half the fun of projects like these
To resolve the steering UJ issue we are going to have to get really creative by making a full-blown block hugger header, or just go turbo so that we only have to pass a single 2.75 or 3” exhaust pipe down through the small gap available. I would much prefer to stay N/A for the sound however!
Oh, and i've found the Solidworks Render buttons which is why the images have some nice polished finishes!
More to follow!
We have scanned in an S2000 header and also the E30 steering rack and cross member. The first issue thrown up is with the steering UJ clearance for the exhaust and the rack pinion area that sits so close to the K20 engine. The original BMW engines seem to be far narrower at the bottom of the block than our K20 does and so have ample room. We may be able to raise the engine but atm we don’t know how high we can move the engine before we run into bonnet clearance issues. Currently the crank position is roughly the same as OEM. Next we need to scan the bonnet and then position it in CAD to get an idea on how much height we have to play with. Another potential issue is keeping prop shaft angle straight and not knowing how far of an angle we can get away with without causing vibration issues. Loads to look into but this is half the fun of projects like these
To resolve the steering UJ issue we are going to have to get really creative by making a full-blown block hugger header, or just go turbo so that we only have to pass a single 2.75 or 3” exhaust pipe down through the small gap available. I would much prefer to stay N/A for the sound however!
Oh, and i've found the Solidworks Render buttons which is why the images have some nice polished finishes!
More to follow!
Edited by Mudgey on Sunday 8th January 20:44
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