M42 Stroker conrods

[shady62]

hi guys just a little question with regards to my stroker build and which conrods to use.
I have the M47 crankshaft and euro s50 pistons, currently awaiting a donor engine to come from a friend. what conrods have been used/ recommend to use> I have read elsewhere Honda B18c conrods have the correct bearing dimensions however is the length ideal or not? being 2mm shorter than m44 conrods.

thanks

[Warsteiner]

Shady62...

You may have read one of my posts about the GSR rods. I found them many years ago and have them in my engine.

I've encouraged people over the years when doing a build like this to get all of your data together and measure everything before you order parts.

If you'd like to use Euro pistons then you're already one step ahead if you decide to use the GSR rods.  They are both 21mm.

It all depends on how you're going to build the engine as to which parts to use. Aftermarket GSR rods can be found. They weigh less than stocker GSR's which I think are on the heavy side.

The reason I say it depends is due to which head gasket will you use? Which rod? Those determine how much you need to shave the piston and pocket the valve reliefs and then dish the piston for proper compression. There is no easy way to throw this engine together unless you order custom pistons already made to your spec which you have calculated.

The lowest compression height that I have heard allowable from RaceTep was 28.15mm. Now that's actually designing and making the piston from scratch. Using a piston from another engine and modifying it, well that leaves questions to be answered like is there enough thickness in the top of the piston?

Lots to think about but nothing too crazy that can't be figured out!!

Keep us posted on your build so we can help guide you along your ultimate adventure!!

Cheers,
~Ralph
2.045L M42 Stroker with xxxHP/xxxTQ hahahaha

[shady62]

Cheers Ralph I have the euro s50 b30 pistons so that would be the 21mm gudgeon pins. I'm aiming for stock CR as it's just for road use and retaining the m42 is my priority. I'm sending the head off soon to have a full supertec +1mm master valve train kit fitted as well as cnc porting to cnc heads up by Manchester so while all that is being done I'm researching and getting together all the parts I need. As you well know info on full builds is rather thin on the ground so any help I can glean from you will be greatly appreciated. Thanks  mate

[Warsteiner]

Shady62,

What crank will you be using?

The experience we have had with S14's using bigger valves is they only help the upper top end flow better. It didn't change anything down low compared to the stock valve sizing. You say it's a street motor so I would think you'd want all the torque you can find. Keeping it at stock compression will limit that factor. I would think about going to 10.9:1 or 11:1 and still be good for the street. You could even go higher and get a bigger set of cams to offset but then you're moving the torque band to the upper rpm range and now defeats the purpose of a nice torque street motor.

Give us a rundown of what you think you want to do and maybe some of the smarter guys on here can chime in

Cheers,
~Ralph

[shady62]

I have a longnosed m47 crankshaft for the build, I'm keen to increase compression if you reckon it will still be alright for it ie no pre detonation. I'm keen to stay on standard engine management too in an ideal world as the electrical side of management boggles my mind. I think soon I'll be shopping for the honda b18c conrods, any manufacturers you would recommend? I'll be going to a reputable machine shop in the uk for the balancing and boring, as there is no one that can do that work on the island Ilive on. I think the base plan list at this early stage is s50b30 crowns (tick) m47 crankshaft (tick) honda b18 conrods (awaiting decision on choice) full head works (just waiting to send away next month)

would you recommend using an m44 or m42 block to build upon? Only I have one of each in the pipeline as a trade for my old m20 that I rebuilt, figured now I don't need it anymore might as well swap it for a load of spare odds and sods.

il see if I can upload some pictures when I get them transferred to my new phone.

[Warsteiner]

It's all in the tuning. You have to find someone that can still tune chips. If you get rid of your AFM then that could be worth another 10HP or more depending on everything else you're using for parts.

I'm not sure about the difference in blocks. I believe they are the same.


Cheers,
~Ralph

[shady62]

Thanks Ralph

I'll keep you posted on this build, it may take some time but I want to do it properly and take my time with it. Watch this space :-)