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mightymini

K20 swap into a R53

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Ok as some of you already know I’m starting a Honda K20 swap into a guys mini. Glad to report that the donor car came in today and to my surprise it started and ran. For the $700 plus shipping I paid for it l think I got a pretty good deal. Will start taking it apart next week, really looking forward to this project. Will post the updates as they progress. Here are some pics of both cars. b4ef07badbb0d26515370523ca7accfc.jpg

 

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Thanks Loui! Today we decided to see if the donor car was wroth it, we found that it cranked but did not start until we noticed the

fuel relay was blown. So we ran the fuel pump directly to the battery and it started on the first try!

 

So Luis took it for a spin and rev the hell out of it. Got to say it hit 8000 rpms easily. I’m very happy :D

 

Damn it! It’s not letting me upload videos but trust me it does sound sweet, here is some pictures of it running.

 

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Tomorrow I will start taking it apart and let the headaches I mean the fun begin. :lol:

 

 

 

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Some progress today, this is the fun part for me I took the engine out and started to make notes of the stuff l will need to make.

 

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Here you can see the difference in Shaft size, the Honda is Beefier!

 

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Today l was able to finish the engine removal from the R53. So,I put them side by side and took some measurements and found that the k20 is longer than the W11 by about 3â€.

 

Tomorrow I will try to install it and see if I get any other surprises. Seeing the difference in sizes It reminded me of a quote my ex girlfriend told me the first time “ it’s looks like it going to be a very tight fit so take your time and put it in very slowly†:D

 

Here you can see the difference

 

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Today we made good progress on the mini. But It was a little touch and go there for a second when I heard someone say that it looks like they may be two cars going to the junkyard cause the engine looked too big!

 

So after a few choice words in Spanish l decided it was time to use my second favorite hand tool and wouldn’t you know it fit like a glove( a O.J Glove)

 

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Still need to play with the left side to be able to use the mini transmission upper mount but it’s in baby! And the hood close with no interference

 

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Thanks Craig, the left side was a bit of a headache. Since l wanted this to be a simple low cost build and to try to use as many of the honor car parts as possible so I could to keep cost down. I met Hammer time on it and took the alternator off to make it fit but next week I will need to trim some metal off the right side so the alternator can fit just right. As you know I like my cars to have A/C so this one will be using it as well as a condenser. Luis wanted to do a new sub frame to fit the larger Honda transmission and yes it would have made it easier but also more costly and timely. For me the fab work is not what I’m worried about it the little things like the electronics and playing with the ecu to get it to run right, those are my biggest concerns. (Picture a Caveman with laptop and that is me) but the good news is that I already told Jim that I am going to be bugging him on his Honda and Emu knowledge and owing him a few lobsters.

 

 

And to answer your question Bill as to why I did not simply use the mini tranny and just make an adapter? Since you know I have already mated a few different engines and trannies before. A few reasons are Time, cost and the fact that a few people already told me that it is too large and would not fit and you know how much a like a challenge.

 

 

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Today was more about taking measurements and getting some supplies for the upcoming fab work and welding but l did managed to make the necessary cuts to fit the tranny and mods to the the subframe.

 

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Here are the templates I will transfer to steel and then weld to strengthen the brace. 82c333e7b6c794b39f78b6f2e15cc17f.jpg

 

 

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Here you go Craig, the low was cut to have access to the drain plug and the upper to clear the rear tranny, I spent a lot of time welding inserts and gusset to strengthen the subframe.

 

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The upper rails also got reinforced by reinstalling the removed piece by putting it in reverse then spot welded to add strength and Rigidness. For now I just primed it and later with finish when the final fitment

 

 

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Also to save time I decided to use the K20 exhaust flange and match it up to an old mini race header that Luis had laying around. Later after the car is running I will consider upgrading to a better exhaust or if the client will want go turbo go that route.

 

Here you can see just like the Honda B16 the K20 exhaust port matches the mini exhaust which will make it easier to match and weld the mini header exhaust runners.

 

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Good progress Jorge.

 

But honestly, after seeing how much of the Mini needs to be cut out to make the K20 fit...this isn't a project for a mini that will see a lot of track use. Not sure I would even consider it for road use, the front end of the car will be like a wet noodle. It likely wouldn't pass any safety inspection here where I live.

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Good progress Jorge.

 

But honestly, after seeing how much of the Mini needs to be cut out to make the K20 fit...this isn't a project for a mini that will see a lot of track use. Not sure I would even consider it for road use, the front end of the car will be like a wet noodle. It likely wouldn't pass any safety inspection here where I live.

 

Thanks Jose and I understand your concerns, But I have boxed welded the cut tubes by using schedule 80 steel both in the tabs and the reinforced gussets. I also welded reinforcement slots into the tubes themselves to add additional strength and to enclose them but rest assure once the engine is set in its final position. I will be adding additional sub frame braces to stiffen and strengthen the chassis as well. So in reality it will be not only stiffer but also stronger than most minis on the street or track running a stock chassis. I will post pictures on the final bracing when done.

 

As to if swapping out to a Honda engine is a good choice that is up to the individual owner. My friend Pedro's classic mini runs a b16 honda motor that I've worked on and has competed and came in second place in the 6 days of Las Carreras Panamericanas endurance races against heavily modified competitors including big time sponsored porsches. Not once in the 6 times he has competed has the engine given him problems unlike the other minis in his class.

 

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And even after a bad accident/flip not only did he survived but the engine also started and is still in use in his car.

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Honestly I personally like the W11 engine but from a race engine builder's point of view cost wise you can not beat the availability of performance parts and low cost of a Honda engine.

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I truly get the Honda Engine appeal...that's why I considered it after I blew up my last engine. BTW I am well aware of the costs of W11 engines and their shortcomings...I'm currently rebuilding my engine for 3rd time. It's always something with these W11's no mater how careful the rebuild....bad rockers/cranks that crack etc.etc.

 

For me it's just to much material to cut out of a car's front structure that was likely was engineered for a reason. If I could build a complete new subframe and didn't need to cut into the crash structure I would see it differently. The Original Mini's with Honda engines generally have a complete new purpose built front subframe (from my research) to support the swap.

 

I'm still going to follow this with interest...but it's just not for me, even thought Honda power would save me tons of money and headaches.

 

Good Job Jorge

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I hear you but something for you to think about in the future if you are still thinking of the Honda swap , you may consider trying what I originally had in mind which was to use a K20 engine with the original mini 6speed Getrag transmission and make an adapter to mate it , this way you won’t have to touch the chassis subframe. I offered and suggested that idea to the customer and/or to a make a new complete subframe but the customer wanted to used the complete Honda combo. He thought it would save time and money.

 

Thanks again for following this thread and maybe I can save some headaches for you or anyone crazy ops I mean interested in doing a Honda swap in the future.

 

 

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If you did an adapter for the Mini trans...then custom fly wheel to use the Mini clutch (for the trans input shaft)? OR??? Honda clutch/flywheel and Mini friction disc??

 

Is there a lot more room if you went this route?

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Yes more room but you will have to adapt in my case the Honda Y2M3/ DC5 bell housing to the mini transmission's main body since the Honda starter is on front and the mini is in the rear of the motor.. This way you can still a use Honda flywheel and pressure plate but you need to use a clutch with the mini spines. Honestly its a lot of machine work and that is why he did not want to pay for it. in fact if you do not have a buddy that owns a machine shop do not do it. The easiest way is to do a new custom sub frame but that is also costly.

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