Yet Another stroker M42

[cecotto]

Nice! The TB's look like DCOE's to me.

aren't dcoe's craburators?

These er decicated for fuel injection. If you look close they have provisions for further machining for a extra set of injectors. For when i'm going with staged injection..... :cool: ... Well perhaps not.. :p

[Tor Arne Kaasen]

Hei steffen otto jensen. nice project. i am also using an m47 crank. But cant deside on pistons. any suggestion? you talked aboute peugot model year etc?

[cecotto]

Hei steffen otto jensen. nice project. i am also using an m47 crank. But cant deside on pistons. any suggestion? you talked aboute peugot model year etc?

Hi' Tor.

I saw you got your Crank from Koed, It looks like a really good deal. I was wondering where that crank went, i could have sold that a few times :-)

I suggest you have some JE's made, you can get those at Koed as well. (I work there, but i'm not trying to be here as a sales man :-) )

About the pegeuot pistons, that is what Lund8200 is doing, i think it requires shawing about ,5mm off the top, and the use of 135mm rods. But perhaps that discussion is best taken in a seperate and dedicated therad for future refrence.

Anyway Tor you should start a thread outlining you thoughts on your project, i love reading about what people are doing.

Cheers

[Tor Arne Kaasen]

i think i have found suitebl pistons at http://www.bavauto.com/shop.asp these are for the m44 85 mm but over sized to 85,485 mm for a nice price.
do you think this will work whit 13,5 rods?

[kowalski]

why not just get custom made pistons?

[cecotto]

M44 Compression height: 30.40mm

M42 Compression height: 31.65mm

You need the Compression height to be 3.5mm shorter than the M42, but the M44 pistons are only 1.25mm shorter, I guess you could shave 2.25mm off the top. The pin is also 22mm so you will be okay there. The M44 has a compression ratio of 10:1, but using the shaved pistons(less volume in piston) will give you a compression ratio increase, Also you're stroked 4.5mm compared to the M44 engine from which the pistons come from, this extra cylinder volume will further bump the CR up. You could compensate with the +0.3mm head gasket. But I have no idea where your CR will end up. Sounds do-able though.

Using 135mm rods will position your pistons a couple of millimeters down the bore, and ruin your squish effect. I wouldent cut that corner..

I also looked into some suitable pistons to use for my project, but i ended up having some custom made.

A moderator should seperate this discussion from my thread, this subject is interesting enough on it's own!

[kowalski]

Well i have a the set of s52 pistons that have the head shaved 1mm already if somone wants to pick them up. it involves boring .20 over, but after that its plug and play. I'm going to need different pistons for my project... so if i've got them if you want them. i believe they give a 10.5:1 compression with the m44 crank and stock rods.

[steve321]

what sort of power do you expect to get??

steve
________
COACH PURSES

[cecotto]

what sort of power do you expect to get??

steve

Hmm..

I hope for approx. 200hp, but i really dont know.. This whole project emerged from my wish for more experience in engine building.. So wi'll see how it ends up.

A little update:
--------------
I ripped a second spare engine apart i had standing in a corner (The doner for the ITB), and it had 6mm valvestems, so i'm thinking about using that head instead.. Only catch is that i will need new spring retainers... The 6mm valves will save me another 140g as i remember.

By budget is kind of overheated at this moment in time, so i'm keeping a low profile in my buying...

This is what i need:
 * Balancing crank
 * Gasket set top + bottom
 * Steel rods
 * Make decissions on the head
 * Engine management
 * Check clearances..
 * Assemble..

[stuartgallafant]

cecotto, your project sounds amazing!

i myself have just found an M47 crank, with the 88mm stroke to use. can you tell me exactly what i need to do to get this to work. i was also going to use custom pistons, but if i can get S50 pistons to work, what con-rods will i have to use?

i just need some ionfo on this, as i feel im a little in the dark!!

any help from anyone would be much appreciated

[tim_s]

aren't dcoe's craburators?

These er decicated for fuel injection. If you look close they have provisions for further machining for a extra set of injectors. For when i'm going with staged injection..... :cool: ... Well perhaps not.. :p

the dbilas TBs use a DCOE manifold to the m42 head and then DCOE-fitment throttle bodies. DCOE can refer to the flange style, not just the carbs themselves.

[cecotto]

the dbilas TBs use a DCOE manifold to the m42 head and then DCOE-fitment throttle bodies. DCOE can refer to the flange style, not just the carbs themselves.

Okay.

They also sell the manifold as a single part, so you could use that if you were to install craburators instead of fuel injected if i understand you correct.  Or use some throttle bodies from another manufacturer instead... Right.

[cecotto]

cecotto, your project sounds amazing!

i myself have just found an M47 crank, with the 88mm stroke to use. can you tell me exactly what i need to do to get this to work. i was also going to use custom pistons, but if i can get S50 pistons to work, what con-rods will i have to use?

i just need some ionfo on this, as i feel im a little in the dark!!

any help from anyone would be much appreciated

Hi Stuart

Good luck on your own project, how about starting a thread on your rebuild. I'm interested in what you're up to...

Have a look at the two poor quality images i have attached.

This image is of my REWORKED crankshaft, This is what has been done to it.

1: Diameter of the shank has been reworked, i cant remember by how much(~0.5mm i think). But the sprocket has a loose fit, so give that to the machinist and he'll figure it out for you.

2: An extra woodruff keyway has been machined in it, as the original is positioned in a way that it has very little contact with the groove in the sprocket. So as a safety measure you should have an extra machined. The angular position of the new one is the same as the existing.

I hope this makes sense.

[cecotto]

I was also going to use custom pistons, but if i can get S50 pistons to work, what con-rods will i have to use?

I'll try and help you out with this. But sorry i dont have any illustrations to back the explanations up....  Even though this is simple stuff, try and go through it slowly, and try and visualize this in your head...

M42 Technical data:

Block height = 212mm
(Distance fron the center of the mainbearings to the deck of the block.)

Rod length = 140mm
(Distance from the center of the large rod bore to the center of the small rod bore)

Compression height = 31.65mm
(Distance from the center of the piston pin to the top piston deck)

Standard Stroke = 81mm

New Stroke = 88mm

Using this data you can do some math and see if the pistons you're looking at will be suitable for your needs, and you can see how different rod lenths will affect your options.

To see how far the piston is from the block deck height:
Position = (Stroke/2) - rod length - compression height
|
212.15mm = (81mm/2) + 140mm + 31.65mm

This means that on the standard M42 the piston at TDC protrudes 0.15mm above the block deck.

Desired Compression height = Block height - (Stroke/2)  - rod length
|
28mm = 212mm - (88mm/2) - 140mm (provided you want the block deck to be flush with the piston)

This tells you that your target compression height is 28mm

All though you might be able to find some pistons that fit this metric, how about your compression ratio??, how about valve pockets??  I looked for a long time for some cheap stock piston, but ended up with some custom ones from JE-Pistons. I think you should seriously consider some custom to, and retain the long 140mm rod.

I hope this helps you,.. Actually on Mahles website you can find piston data.

[stuartgallafant]

i was thinking of going custom pistons and remain using the 140mm rods. so if i have the M47 crank, i just get the machinist to make the woodruff key to fit on it, and all will be fine?

also, i think i have found a company that will produce some fast road cams for me. should i buy the cams, fit the crank, and then get the pstons made to suit the rest of the spec of the engine?

i will start my own thread soon, once i've got everything i need!!

thank you for your help