C.D. Heard you have/had a stroker motor?

[winstontj]

Are you running an S14 84mm crank with M10 rods? If so what pistons are you using?

Would like to try this out and I'm wondering if it was BMW OE parts or something custom.

Thanks,

TJW

[BillWilliams]

that is what my motor is in the yellow little car and it has custom JE pistons. Eric Kerman built the motor

[jerry]

that is what my motor is in the yellow little car and it has custom JE pistons. Eric Kerman built the motor

bill+others,

could you expand on your motor a bit? i've been keenly watching all threads related to S14 cranks used in 02 motors. what exactly is the custom aspect of your pistons? are they the NLA bathtubs? or a modification of an existing design?

did you have to grind additional clearances on the engine block for the rods as Schnell540 photographed during his build (little recesses at the base of the cylinder bore)?

i've been confused as to whether M10 rods were useable or whether they had to be S14 rods.

[Anthony]

There is a lot of information that can be found in the search, but the skinny is:

Stroker crank by definition means more stroke in this case 4mm which translates into 2mm up and 2mm down.

If you use the stock rods and pistons with an s14 (84mm crank) your pistons will stick up 2mm proud of the block. So you need to use pistons that have the pin height relocated up 2mm.

The stock rod (135mm) is pretty low (1.68) in the rod/stroke ratio department and when you add a s14 crank it gets worse (1.60 - considered by many builders to be the absolute minimum) , so most people elect to go with the longer 144mm rod from the s14/s38 motors. think about it why did BMW go to the longer rod? Many m10 builders also use the long rod in a otherwise stock motor (m10) and just this AM I noticed that Ireland Eng. is advocating the use of a long rod and they have some very beefy and relatively cheap (in the money department which is good!) rods for sale on their site.

Long rod, short rod, oversquare, short stroke all have different characteristics and I would suggest that anyone would do their own research to see which features are the most congruent with the intended use for their motor. In general terms a short stroke will make more torque sooner and a long stroke can help with breath up higher (increase dwell at TDC and slow down piston speed)

Now if you go to the longer rod (+9mm) the pin height needs to be relocated an additional 9mm to account for this.

Anthony

[winstontj]

that is what my motor is in the yellow little car and it has custom JE pistons. Eric Kerman built the motor

Would you mind me asking for a ballpark range of what I should expect to pay for a set of said pistons? Are these stock custom or custom custom? I don't want to have to send out my block and head. I want to be able to order parts and assemble at will.

Thanks,

TJW

[Anthony]

Tom,

All vendors I know, have designs already made to work with your stock head and Kerman is no different so if you call Ireland as an example they have an e12 design with relocate pin height. Cost is $550 to $700. No need to send you head out but you will need to bore or hone your block.

[winstontj]

Tom,

All vendors I know, have designs already made to work with your stock head and Kerman is no different so if you call Ireland as an example they have an e12 design with relocate pin height. Cost is $550 to $700. No need to send you head out but you will need to bore or hone your block.

Anthony,

You mentioned to me once about S14 'blue' bearings? I'm going to need to have my crank polished up pretty good. I have all of your emails - should I factor the polishing in or assume that it won't change the journal size and keep stock bearings?

I'll call around in the AM and order up a set of pistons. Any suggestions for CR with the 292 cam? I'm thinking 10:1 is max but could I run 10.5:1 on regular 89 crap fuel?

[Anthony]

It totally depends on what your crank measures to. You need to see what the size is before you commit to a bearing size

Here is a good post by John Aho

While their rod bearings are different, M10 & S14 mains are the same.

The red & blue sets from BMW were made to fit slight variations in crank journal sizes during production.

They would check & sort cranks by size, marking them with paint.

The Blue bearings could be used to achieve the correct clearances on a crank that was detected to be finished very slightly undersized (~ 0.0004").

BMW specs for the journal sizes need to be read & understood carefully.

The nominal main journal size is 55 mm (2.1654"), but the actual size is indicated by the dual negative tolerance, which results in a range always less than 55 mm.

For example, the standard size is 55 mm, with the RED tolerances limits of - 0.01 and -0.02 mm.

That means your 55 mm crank journal will never be 55 mm, it will be between 54.98 and 54.99 mm to fit the spec for RED. (BLUE is smaller still, std BLUE is 54.97 thru 54.98 mm)

BLUE sizes are not available in the aftermarket, which sucks, because many perfectly good old cranks would now be a good match to BLUE after a quick polish. BMWNA charges a bunch for these.

RED sizes are what the KS, Glyco and others sell for aftermarket.

One warning about RED/BLUE specs..

I've seen Federal Mogul spec books (that many crank shops use as their bible) list only the BLUE specs (which probably won't match your new bearings.

If you are getting the crank work done, be certain you know & can explain to the shop what the factory specs are for your setup. Xerox the spec page from the manual & show it to 'em.

[winstontj]

Tom,

All vendors I know, have designs already made to work with your stock head and Kerman is no different so if you call Ireland as an example they have an e12 design with relocate pin height. Cost is $550 to $700. No need to send you head out but you will need to bore or hone your block.

Hey qucik follow-up if you're still lurking around.

What is the best way to address the front seal? Ireland said that it's better to turn down the crank than to bore the timing cover. I'm weary of that because of how well the S14 crank is hardened. Not that the front cover really matters - but I'd rather bore the cover and run the S14 front seal. Thoughts on this? Additionally on the front seal topic - M10 or S14 pulley?

Thanks all for your input, especially Anthony for putting up with my antics!