Half The Cylinders, Twice The Fun: The M5-Powered 836CSL

It’s a sad fact that BMW never made a road-going ‘M’ version of the original 8 Series coupe. Sure, they teased the public with a skunkworks M-division beauty, but it never made it past the accountants. For most BMW fans this leaves a gaping wide opportunity to reimagine what could have been if an E31 BMW M8 were to exist.

‘But there is a production M8,’ I hear you scream.Well yes, technically you are right. But for the purpose of this article we’re not talking about the slightly bloated (but incredibly powerful) grand tourer. And that’s not a dig at the G15 platform; it’s just a totally different breed of car compared to its ’90s predecessor. We’ve skipped a few generations of BMW since and, in my opinion, it sits in an entirely different sphere to any E31. We’ll save that for a future discussion; let’s enjoy E31s for a second.


BMW’s vision of a hot ‘M8′ followed the oh-so-’90s tuning rulebook of more is more. They absolutely embraced the world of carbon fibre, making just about everything that wasn’t bolted down from it. The pumped-up wide arches, mirrors, wheel covers, intake plenums and ducting were just some items made of the good stuff.

The engine for the M8 concept was based on BMW’s M70 12-cylinder that grew to 6.1-litres, sprouted a couple more cams and individual throttle bodies. Couple this with deleted headlights (to clear the S70/1 V12’s air boxes) and an Alcantara-clad interior and you’ve got something that wouldn’t be out of place in a ‘dream car’ discussion down the pub. Unfortunately only one car was built, although a ‘watered down’ 850CSi was available. If you can call a 375bhp 5.6 V12 coupe watered down, that is.


But that’s enough of the OEM history book. Let’s kick off the shackles of marketing feasibility and brand perception in favour of something much more interesting. What happens when you build your own sporting 8 Series, using nothing but your favourite parts free of anyone looking over your shoulder? Unsurprisingly, a man in Japan has done just that, and he goes by the name of Masahiro Ito.


Starting out with an 850i as a base you’d assume Ito-san would travel down a V12-shaped rabbit hole. After all, that’s what the M8 concept did. But he’s thrown a fantastically Japanese curve ball into the mix, one that takes the shape of an S38B36. If you’re a BMW nerd (like me) you’ll recognize this string of numbers and letters as being the six-cylinder lump BMW crammed into their E34 M5.


This engine was chosen because of Ito-san’s fondness of his old M5, helped by the fact he casually had a spare lying around. “Before buying the E31 I had an E34 M5 that I used for drifting,” Ito-san explains. “I preferred the look and style of an E31, but there was no sporty option available. So I decided I would make my own version instead.”

Considering the replacement engine boasts half the cylinders, it looks right at home in the front of the big coupe. In fact, BMW never offered an E31 with anything smaller than a V8.


With the mixed intentions of street use and drifting, it was obvious that a manual gearbox and locking rear differential would be essential to the build. While a manual 8 Series was available, one thing to factor in is weight. By swapping over to the S38 engine and 6-speed box, Ito-san has saved 100kg over the V12 and auto box it replaced. That’s a whole me (after Christmas) of weight evaporated into thin air without sacrificing too much horsepower in the process.


But the weight saving doesn’t stop here. Harking back to the M8 concept, Ito-san has extensively used carbon fibre throughout, including the roof panel. On the back the 8 Series wears a CSL badge as a cheeky nod to the E46 M3 CSL that spurred the composite roof idea. Maybe this 8 Series has more in common with the straight-six CSL than even the M8 prototype?

Either way, Ito-san’s creation tips the scales at a respectable 1,590kg (3,505lb). That’s mighty impressive when you consider a road-going 850i could be anywhere between 1,855 to 1,975kg (4,090 to 4,354lb) depending on engine and spec. This is all thanks to the engine and drivetrain swap, but also lightweight body panels including both bumpers, bonnet and of course the roof. Those titanium tips aren’t just show; the entire system is made from it, shaving an additional 25kg (55lb). How about the removal of the stock leather arm chairs? That saved a whopping 80kg (176lb)! In their place are a pair of Recaro buckets; a recliner giving the passenger some comfort while a fixed back driver’s seat makes the whole thing feel very Japanese. To complete the diet, Ito-san removed the ABS system and swapped out the stock battery for a lightweight motorsport one.

Ito-san is absolutely talking my language in the way he’s been able to shed masses of weight without making the car look like it’s trying too hard. That’s how you make something ultra cool in my eyes; it’s effortless.


It’s not all form over function, however. Nobody can argue that the pearl white paintwork is anything but a pure expression of Ito-san’s style. Originally Alpineweiß II, which is a rarity in itself, the added pearl accentuates the muscular arch lines that are often lost in dark, understated colours on an 8 Series. Close down Google before you waste too much time searching for that front bumper; it’s handmade and totally bespoke.

I can help you on the wheel and tyre front, though; it uses Enkei RS05RRs in 18×9.5-inch with 265/35R18 tyres all round. 8 Series fans reading this won’t need to worry about asking the embarrassing ‘specs please’ question.


Flicking through Mark’s images of Ito-san ‘s 850i (nicknamed the 836CSL) triggers that familiar desire to create something similar myself. That is until I learn that it’s taken Ito-san a decade of ownership, development and enjoyment to get to this point. It’s the sort of car that carves its own path with love and use and ends up ‘real’ because of the lifestyle and choices of the owner. It is really a reflection of Masahiro Ito.

DSC00665 2

With this in mind, it leaves just one question left to ask: How would you build your ideal E31 8 Series? Let me know in the comments and we’ll see if we agree.

Ryan Stewart
Instagram: 7.nth 

Photos by Mark Riccioni
Instagram: mark_scenemedia



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Once again the shots are trully amazing, and the article is well written ! Love from France.


TY Gabriel, glad you enjoyed!


I am not the biggest BMW fan but I like this build. I would just swap in a turbo engine though.


As an owner of S54 and an S55 powered BMWs, it's NA all day!


Love this engine to the moon and back. Love the E31 aswel.Make $6,000-$8,000 A Month Online With No Prior Experience Or Skills Required. Be Your Own Boss And for more info visit any tab this site Thanks a lot…Start here>→→




Individual throttle bodies not your thing?


Love this engine to the moon and back. Love the E31 aswel.
But, if you don't mind, I'll take a V12 850CSI. S70B56 (L)


Bloomin' lovely that. I like the idea of one with the V10 from the F10 M5......


Oops, I think I mean the E60 M5....

Jay Soh Tsu Chung

We're in the same boat mate!


Since this chassis definitely doesn't match the ideology of a road-legal track car, I would try to modernise it with interior parts and systems from recent BMWs while keeping the special E31 features such as dashboard turned towards the driver and a bodykit similar to the hero of this article. As for power, I would keep swap the engine for a newer and lighter V12 or the S85B50 V10 from the M5 E60 spiced with a supercharger kit. Another idea is really weird but impressive: turn it into a drift car and install the 9.5 V12 LS engine, recently developed by Australian tuners.


I would really like to see a S85 under the hood of the beautiful E31. Full leather and alcantara interior with maybe some new navi system from a newer gen car and a full suspension reevaluation, maybe air ride? (not the stancy but the practical one)


And, Happy.



I've seen a few videos on swaps like this on YT and they were all japanese, one of the cars might have been Ito-san's, because I remember seeing a white one!
I absolutely love this build (and the pics too, Mark never disappoints). I like the V12's sound a bit too much to swap it out, but for the weight you save on using a 6 cylinder, which sounds just as good and makes "about" the same power, it's an ideal swap. I love the S38 (the E34 M5 is my dream car) but I'd go with an S50B32. Peak torque is much lower and the power figures aren't all that different from the S38B36. Maybe in the future I'll get to building of for myself ;)


An S54 would also be an interesting option but might look a little too modern...


I'd rather go with an S50 than an S54 anyway, the S50 has more torque down low and doesn't need so much revving to make an heavier car move ;)


There are definitely some cool videos of it on youtube from 10 years ago.


BMW boss : How do ve make ze BMW car more cool?
BMW engineer: Ve cud add pop-up headlamps.


Damn that drivers its LOW.... :) thumbs up!!!!


BMW V12 from the F1, the ultimate 8 series needs the ultimate V12. manual box, similar weight removal to the '836' custom suspension from Exe-TC, get it riding well and handling even better and a big brake kit.


Fantastic engine choice! I truly love the E31 exterior styling I just wish the interiors had aged as well. Gone back and forth over getting one for years but I will say that this is one of the best/coolest E31 builds I have seen.



The interiors have aged well I think, they have a slight air of Supra 'flight deck' about them.


I hate to type this as I generally don't like to post negative comments but I am and always have been so torn over this issue with the E31. I feel that the exterior is arguably the most beautiful BMW ever created. The E31, 34 and 38 are just gorgeous examples of exterior design. But the interior of the E31 has always been too close to the Ford Probe to me. If you pull up photos of both online, you will see what I mean. But please make no mistake, I still love the cars and particularly this example. I have built quite a few BMW's and have always/and still do want one of these but the interior is where you spend most of the time in a car and I just wish it had more style cues from other BMW's of the era. That also didn't stop me from searching out E31's for sale again after reading this feature and it helped re-ignite my love of the exterior design.


I'll preface my comment by saying, I'm a self admitted Koenig fanboy.

If I had one, I'd go full Koenig Specials with it.. The Koenig KS8 (I think it was based on either an 850i or 850CSI?) is one of their most tasteful kits/cars, with just a bit more added aggression from the wider front/rear fenders and OEM style rear spoiler, that still manages to retain an OEM appearance at the end of the day. But, I'd also put it on a diet where I could.. Wheels, seats, exhaust system etc.

Brennan McKissick

I had to google the Koenig Specials KS8. Damn, that is some 90s goodness right there. That's damn near perfect.


To all you people dreaming of an S85 V10, there's a very good reason BMW stopping making it. The S85 V10 engine had a nasty habit of eating its own camshaft bearings after 35k-50k miles. This then causes the engine to self destruct. BMW doesn't build these engines anymore, and professionally rebuilt ones are in the $40k to $50k range.

Obviously, BMW has found much better ways of building high horsepower numbers without requiring more than eight cylinders. A shame all of those options today incorporate turbos, but if you're willing to settle for slightly lower horsepower to get more reliability and simplicity, other options exist too.


The S85 is a fantastic engine and the noise is hard to beat. The biggest downfall of the V10 is it's lack of torque though.


Also, BMW didn't stop making these engines due to the inherent problems they all share. Emissions regulations in the EU forced these engines out of production. Turbo-charged engines make more horsepower more efficiently, even with regulatory emissions control equipment fitted.


It's not the camshaft bearings it eats. It's actually the rod bearings. This problem is also shared by the S65 by virtue of the fact the S65 is literally an S85 with 2 cylinders chopped off. The S54 also has known rod bearing failure problems (I know - I own a 90k km e46 m3 which spun a bearing recently). The rod bearing issue on all of these motors is due to an engineering design flaw where the crank journals are too narrow for such a high revving engine, and the tolerances between the rod bearing and crank journal are extremely tight; therefore after X km of use, oil starvation causes one or more bearing/s to spin. Contrary to what you've said, you can actually still buy brand new S85/65/54 complete engines from BMW. Idk the price of the S85/65, but an S54 is ~$40k AUD brand new from BMW. S54's run ~$15k AUD second hand, while S85/65's run ~$20k+ AUD second hand.


Thanks so much. Your reply pretty much proves my point. When I read about these fantasy engine swaps with S65/S85 engines, please imagine me staring back at these people as if they were dumber than a box of rocks. Not trying to kill anybody's dreams, but BMW engine swaps are probably the easiest way to go broke other than to go professional racing without sponsors. Anyone willing throw acres of cash into the BMW money incinerator is either already in the top one percent income bracket, or has completely lost your mind. Anyone who thinks it takes more than eight BMW cylinders to propel a BMW quickly has no clue what they're doing.

Let me tell you why. BMW engine blocks are virtually useless for any kind of cost effective horsepower enhancement. The blocks are made of silicon alloy that is almost impossible to hone, overbore, or modify using conventional block enhancement techniques. Don't waste your time or your money.

Price a rebuild on BMW engine anywhere you want. I promise you it will almost never be cheaper than low five figures minimum. Anyone who claims they can is either lying to you, scamming you, or is planning to cut corners somewhere to ensure your high dollar joyride is as brief and expensive as possible.

For less money than one of these low five figure rebuilds, which will rebuild only to stock horsepower numbers, you could get a new LSx or Coyote swap V8 and be knocking on the door of 500hp, with a transmission, for $10k to $12k. Heck, you could even splurge on Chrysler's Hellephant engine (a 7.0L. 1,000 hp version of the Hellcat) for $30k. Think about it. One thousand horsepower for $30k. Or you can pay BMW MORE money for just half the horsepower and two cylinders more than you need.

Think about it.

Car enthusiasts can either applaud your ingenuity or laugh at your stupidity.

As for those who shudder at putting a non BMW engine under your hood, I ask, who's going to be checking under your hood at 60 mph (100 kph) anyway? Who's the more important person to impress? Yourself, or some anonymous troll on the internet?

Just my $20.02.


Wow, I bow to your superior technical knowledge as I am dumber than a rock. Lighten up a bit sunshine....

Jay Soh Tsu Chung

If it were me, I'd still go with a BMW engine. I'm very much a purist. I mean, sure, a 6-cylinder may do the job as well as the S85 does, but they just doesn't have that high-revving characteristics and wailing exhaust note that the V10 has.


Not all BMW "S" engines are alloy of some kind. The S85/65 yes, but S54 is an iron block.

I'll keep my reply short, and while I agree with you 100% about being able to get a shitload of horsepower out of LS engines among others for a relatively small sum of money, there is nothing that can match the BMW "S" engines out there for pure naturally aspirated and small capacity performance, design and sound. Yeah they are very expensive and a big task to maintain correctly, but the scream of a naturally aspirated inline 6 with ITB's is just divine.

I'll stick with my iron block ~300rwhp S54 all day every day. Much rather that than an LS or similar making double the power.

Just my $0.02 :)


S52 is an iron block. I have one in my Alpina B10, and guess what... I put a hole in the piston. With that said I can accept that it's my own fault for supercharging it. You can't always blame the engine designers. I hear everyones comments on the 'BMW bearing problem' but people forget these are highly strung engines with a huge NA output. It's impressive they are in widely available consumer cars at all. Sure a road car should be 'turn key' durable but don't forget engine bearings are an item that wear. They will not last forever. I've owned an S65 V8 M3 for a wonderful few years and driven it very aggressively. If you look after these engines they will look after you, if your swapping an S85, S65, S54 or even S50/52 just budget for bearings and enjoy them. They are all incredible engines.


Now this is the type of stuff I like to see on Speedhunters. Great build and some real good inspiration to keep going with the pretty complex plans I have for my own project.


Tell us about your project!

Spencer Slaughter

Well I actually just hauled home my engine swap candidate 20 minutes ago - an AAN 20v turbo inline 5 cylinder that came out of either a first generation Audi S4 or S6, known as the UrS4 and UrS6 among Audi enthusiasts. I'm not sure exactly what engine this car came from because I bought it from a guy who bought it from another guy who had it in a shed, but I'm going to rebuild it so I'm not too worried about that.

Anyways, my project car is a 1988 Audi 90 Quattro in Almond Beige Metallic with a tan on black leather interior and a 5 speed. This car has the 10v naturally aspirated 2.2L 5 cylinder known as the 'NG'. 5 cylinders is cool and all but 130 horsepower isn't all that cool lol, so that's why I'm doing the swap. And also because it would be a lot more expensive to try and build up the NG. In terms of complex engine swaps, this is not the most difficult swap ever but for someone who has never done an engine swap, it is pretty intimidating. My plan for the build is to restore everything on the car that needs it and get it looking like it did when it first drove off the lot, and to also get the swap integrated as nicely as possible; end horsepower goal is ~400 but we'll see if I'm able to stop there for good once I get there.

Like I said, it's nice to see builds like this 8 series on Speedhunters. I wish it was easier to find builds like these so that there'd be more on here but I understand speedhunting isn't easy. The build itself is pretty close to flawless, but it's the amount of time Masahiro has owned and worked on this car that is the real inspiration. It's not often when you hear someone say they've owned their project for 10 years and have also been building it and perfecting it that whole time. That takes real dedication. Can't wait to see more builds like this and thank you Ryan for bringing this beautiful build onto Speedhunters.

Now I'm gonna go get started on stripping down my AAN!


Very well sorted. Great build!


blow off valve no more


Once every few years, I see a build that stops my heart and then restarts it with a happier beat than before, and this is one of those very special few. Is this the car that once sported a Mitsubishi GTO front spoiler? That’s the white car on YouTube with the s38b36 swap.

That carbon roof and custom titanium exhaust would cost more than installing the s38 and getting the two wiring harnesses to play nicely. To say the “CSL” diet is impressive is a massive understatement! If I could do my own, cost no object, I’d want a built S62, like the crazy 550-600hp motor Dinan stuffed in a clown-shoe M-Coupe, or the driveline out of a certain, Godly E38 “M7” feature car, running a blower. Once I was hooked on BMW V8 sound, there was no going back!


Thank you! That white supercharged S62 E38 was the car I built and then sold on BAT.



Incredible build, BMW fan very satisfied right here. Front engined M1 vibes (especially with the custom bumper). The paint does look killer on the rear fender arch. Just WOW


I also thought about the parallels with the M1 but thought the engine placement a little too abstract to mention it. Glad I'm not going mad and someone else thought the same.


Super Unique Car Super Nice


850 CSI not CSL))


The 850CSi is the top tier factory 8 series from BMW. This one is a 'CSL' because of the owners inspiration for the weight saving.

Brennan McKissick

I'd definitely have one of these set up as a GT car. I think the S38 is a great motor for this car along with the 6 speed. I love the wheels but I'd probably go with some AC Schnitzer Type 2s. An adaptive suspension similar to the Mag Ride that comes in newer top trim cars would suit the build as well. For the interior, just some updates similar to what a Clarion build would get along with some reclinable Recaros. Weight savings all around would be nice too with painted carbon on the body where available.


Pop up headlights. That is all.


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I'd probably leave the ABS intact, dump stuff like AC instead.


Ive seen pictures of this thing from like 10 years ago, blown away that its been M5 swapped and is still around and kicking