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supercharged V12 2 stroke

Methanol burning beast!!

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dean clarke 218/09/2015 12:50:15
155 forum posts
330 photos

Well, I'm still alive and kicking just in case anyone was starting to wonder?? Um been a little while since I updated this thread so I thought I should probably get onto it. So here it is, the next installment of this build. Having gone slowly mad trying to lap and polish 12 liners I have finally been able to finish this step of the build. I have also managed to make a pattern piston from ally to figure out the final dimensions of the pistons. This was somewhat of a frustrating excercise but I'm glad to have done it now as I think I have managed to get it sort of right at last.(joys of scratch building without any drawings lol). here's a photo of the progress to date including a couple of further mods to the conrods.v12 liners and rods (1).jpg

v12 liners and rods (2).jpg

v12 liners and rods (3).jpg

This last shot shows the development of the conrod profiles to get them to rotate through the full cycle without fouling on the piston anywhere. The piston on the left was the first try and the one on the right is the final design ready for machining the cast iron pistons, which is the next step in this long drawn out saga of a build. Apoligies for taking so long but I have been sidetracked countless times with work and home demands. Also there is another slight confession I have to make..........The cylinder block at the start of this thread is actually the second attempt at said part...... the first one was almost left as scrap after i accidentally machined one cylinder bank off while milling in the valley section of the block, luckily I hadn't started on the sump side so I just put it aside and made a new one. However being the tiger for punishment and possibly slightly rattly in the head I had another look at it a while ago and prompted by the comments from some about fuel consumption I thought I'd salvage it into a flat 12 engine block and build it the same as the v12 but naturally aspirated. The flat 12 will be identical to the v12 in everything except the fact that its a flat instead of a vee design and it's not supercharged, The cylinders are setup in the same matched pairs but will be running on separate big end journals so that each pair will reach tdc simultaniously, the crankcase being sealed into individual compartments by the center main bearings. Below are some photos of the progress to date........... Once both engines are finished and running I'll be able to do a few tests on fuel consumption and power output..

flat 12 block.jpg

flat 12 block 2.jpg

flat 12 cylinder blocks and heads.jpg

flat 12 liners and conrod blanks.jpg

And yup thats another set of 12 liners to hone, lap and polish............... someone shoot me will ya.

Well thats it for now I'll try and be a bit more onto it in future

Cheers for now


Nick_G18/09/2015 14:01:18
1808 forum posts
744 photos


Totally fantastic. smiley (that is all to be said)


Michael Gilligan18/09/2015 14:38:27
15016 forum posts
644 photos

Great to see you posting again Dean

Amazing Work


Ady118/09/2015 15:24:10
3583 forum posts
514 photos

Well, I'm still alive and kicking just in case anyone was starting to wonder??

Was wondering last week. Didn't want to post a query though.

I think I have managed to get it sort of right at last.(joys of scratch building without any drawings lol)

I know. V12s can be a bit of a bugger when you have no drawings

Glad to see you're still going Dean, inspirational stuff

I thought I'd salvage it into a flat 12 engine block and build it the same as the v12 but naturally aspirated. The flat 12 will be identical to the v12 in everything except the fact that its a flat instead of a vee design

So you're doing a flat 12 AND a V12 now. I'm lost for words


Edited By Ady1 on 18/09/2015 15:44:20

Neil Wyatt18/09/2015 19:23:16
17375 forum posts
690 photos
77 articles

Welcome back


John Olsen19/09/2015 07:07:29
1017 forum posts
86 photos
1 articles

A link was just posted on the RCME site to a video on Youtube about the manufacture of RR Merlin engines. I thought it might be of interest to those following Deans build, although the gear RR use is rather larger than Dean has!


Thanks to Jon Harper who posted the original link.



HomeUse19/09/2015 12:43:08
168 forum posts
12 photos

Hi Dean - Glad to see the update - keep them coming as it is a great project wink

dean clarke 218/10/2015 05:41:29
155 forum posts
330 photos


So life it seems is never simple or easy and often fraught with danger and frustration. It seems so also is model engine building or more precisely the use of machine tools! I was working away on the manufacture of the pistons for the v12 when suddenly there was an extreme excess of machine oil in the immediate atmosphere around me. The seals on the quill of the mill decided that it was time to not do anymore sealing, consequently i have spent the last little while stripping the mill machine head down and giving it a good clean and regrease and replaced all the seals. So now it's on with the show. The photos below show the progress to date on the making of the pistons.

v12 piston blanks.jpg

v12 pistons stage 1.jpg

v12 pistons and tooling.jpg

v12 pistons and fixture.jpg

Hopefully I will get a bit more time in the shed to complete them this coming week so thats all for now folks



Edited By dean clarke 2 on 18/10/2015 05:42:35

Danny M2Z18/10/2015 06:21:29
804 forum posts
282 photos

Good to see you back on the job Dean.

Piston material looks like cast iron - excellent.

Seeing as how you have made a piston holder for lapping the pistons, and as no two cylinders ever come out precisely identical in dimensions (tenths of thou), I have found that lapping a piston to fit the largest bore first is the way to go.

If you are a little bit over keen then it might fit one of the other cylinders and by the time that you have all 12 done you shall be quite good at judging the fit.

Tallow (rendered fat) is very good for testing piston-cylinder fit.

I shot a large feral pig to obtain my tallow (.444, twice size a Dirty Harry .44 Magnum) but your local butcher might be more useful than my Marlin lever action pig hunting gun.

Keep up the good work, a lot of people are interested (check the views)

Regards from Down-Under

* Danny M *

HomeUse18/10/2015 09:19:59
168 forum posts
12 photos

This may be a stupid question but is there any reason for some of the pistons having a domed recess in the bottom of the bore and other do not (8 do 4 do not) embarrassed

Keep up the good work

dean clarke 218/10/2015 18:44:09
155 forum posts
330 photos

LOL, Um i would love to have some highly techo reason for the domes but the simple truth is they were pilot bored with a ball nose cutter which i found to be much quicker than the drill and turn option i started with. the pistons are not shown finished, just at the first stage of machining. the next stage is to machine the skirt off on the back side and then mill in the recess for the conrod to sit in. then its onto the non-expanding end of the fixture to be turned to diameter for lapping and turning the crown down to final length. Then its machine the step for the transfer into the crown and finally lapping to fit the liner. Each piston is fitted to its mated liner. I will endevour to have them all done by the end of this coming weekend.



HomeUse19/10/2015 09:51:52
168 forum posts
12 photos

Thanks Dean - “I had vision of massive calculations to adjust the weight of each piston embarrassed “ - But I really knew that it was a stupid question.

Hope the final lapping goes well

Regards Mike

dean clarke 226/10/2015 08:15:43
155 forum posts
330 photos

Well here we are at the next stage of machining the pistons, The first step in stage two was to cut the step into the piston skirt. There are three reason for this, firstly to allow clearance for the piston at BDC from the center main bearings and secondly to give a sealing skirt over the exhaust ports at TDC.Lastly just for some lightening effect. Next they were set up centered in the mill to machine the conrod little end space into the underside of the piston and then lastly, all pistons were machined at the crown end to the final overall length. Photos below show progress to date.

pistons stage 2.jpg

This photo shows the setup to machine the conrod little end recess.

piston machining 1.jpg

Don't ask about the piston on the left..................... Yea lets just not go there OK.

The photo below shows the fixture used to turn the crown down to length, which will also be used to turn the diameter to lap to the liner

piston crown machined to length.jpg

Here are the 12 pistons finished to the end of stage 2. Next is to machine the transfer advance step into the crown, the object of this is to advance the transfer timing so that it opens approx 10 deg's before the exhaust and therefore stays open 10 deg's after the exhaust. The point of this is to allow a small amount of exhaust gas into the transfer port to reduce the loss of fuel mixture out the exhaust on transfer. With approx 25 psi boost pressure there will be plenty of SUPERCHARGE in the combustion chamber on the compression stroke.

pistons ready for transfer advance step to be machined.jpg

Well that's all folks see you again soon



dean clarke 215/11/2015 07:58:54
155 forum posts
330 photos

Well here's next step in the process of fitting up the conrods and pistons. I have managed to fit all the rods to the engine and have finished and lapped 1 piston, this could end up taking a while!!!! maybee i need to just work a bit faster? photos below show the progress to date.

conrods fitted (1).jpg

conrods fitted (2).jpg

conrods fitted (3).jpg

sump fitted.jpg

That's all for now


Ian S C15/11/2015 12:16:29
7468 forum posts
230 photos

Don't rush it, or you'll get finished and have to think of what next, great work Dean.

Ian S C

dean clarke 228/11/2015 05:01:23
155 forum posts
330 photos

lol, halfway through the piston lapping and finishing at the moment, will post photos when all done. Next project is already under way.

Cheers for now


David Colwill28/11/2015 06:48:47
610 forum posts
33 photos

Dare we ask what it is?

Looking good so far. Keep up the good work Dean.



dean clarke 229/11/2015 07:14:19
155 forum posts
330 photos

Well that would be telling now wouldn't it? needless to say i will be doing some drawings before i start this


dean clarke 210/12/2015 07:46:03
155 forum posts
330 photos

Well here we are with a bit more progress, slowly but surely I am getting there. Photos below show the advancements to date..................

pistons half way there.jpg

pistons half way there 2.jpg

pistons all but 1.jpg

Yea, all there bar one, just had to be one that didn't want to play the game............. oh well better make another one.

cheers for now


Dave Powell 210/12/2015 09:05:07
33 forum posts
11 photos

What a fascinating project, can't wait to see the next bit!

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