FM stroker alternative?
 

Does anyone know if someone has tried to put together a cheap alternative to the FM stroker design? I'm sure the biggest issue is the crank, since it's a custom design and can't be cheap.

Why not just go FE3 instead?

What do you consider to be cheap?

Cheaper than 5 grand.

This is the cheap option. If running a non-miata block is an option.

Isnt there some other company that has a stroker setup? But under 5k? Good luck even getting a standard boost build for that cheap if you're paying someone for assembly.

There's always DIY, have a stock crank offset ground (my gut says 4mm is a lot though), and find an off the shelf rod with the new correct big end diameter to at least order bearing from, maybe it'll be the right length, else you'll be ordering custom, and get custom pistons.

There's some company doing it for like 2 grand iirc

we discussed it last year I think

I figure I can do all the work myself. I have everything except transmission tools, I just figured someone may have already done the legwork. Sadly, a search has turned nothing up so far..

Maruha's 2044cc (not 2.1L as they advertise it) stroker is ~$5000USD. There are no other kits available that are any cheaper...yet.

you could get some custom rods from someone that is not carrillo for cheaper, and maybe talk to moldex directly about the crank, and you can get the same pistions from weisco directly without the FM tax. maybe be able to get it for 4500.

IMO the .2L of displacement doesn't justify the 5k. You are never gonna break the stock crank. No one on this forum is going to break the stock crank ( with proper tuning). You dont need a billet crank untill you start breaking 650hp maybe even 750.

And what are you gonna gain ? an extra 25-50 ftlbs? For 5 grand its not worth it.

You can drop in an FE3 for under 2 there's a handful of those on here

Thats why I suggested an offset ground stock crank. You would need to do that math (and by that I mean simulation) as the 4+mm reduction in diameter will noticeably reduce the strength and stiffness of the crank.

The gain is more for the spool. The other turbo miata I've driven has an FM stroker and a disco potato on an FMII setup, it feels like the turbo really isnt there. I havent tuned my boost control enough to really see if 'stroker 99-00 + normal turbo' is better than VVT + EFR. My gut says the better turbo and VVT is going to be better than the stroker, at the very least I will be winning in the transients.

McCully Racing Motors- Don't want a V8? How about a 2.0?

Still have yet to hear of anyone actually running one though.

yep, that's the one I was talking about.

3k for the really simple version looks like.

I still don't see how its worth it, even at 3k

Yeah F**K sleeving. Nothing but a problem waiting to happen. The whole greatness of our motor is the stout iron block. Why on earth would you put a F**king sleeve in it. Might as well buy a honda and actually make power.

Wait is your end power goal around 200? Because then you don't need to build a 1.8, you can just swap in a stock running one and boost it.

That's really subjective, though. No offense, but I know for a fact that you don't care about low-end torque - I've seen your dyno graph. :fawk: For someone who's got an EFR6258 and wants to add another 100whp without sacrificing any low-end, a stroker would let them jump to an EFR6758 or a 7163, make the same low-end torque, and add a lot of power up top. They might consider the extra ~$3k in the engine an acceptable price tag to get that mixture of characteristics. There are people out there who spend big, big bucks on naturally aspirated motors because they want a specific set of characteristics out of it. You don't have to understand or agree with those people (although I do), but you do have to at least acknowledge that they exist.

Comparing a sleeved BP block to a Honda block is just stupid. The Honda block is an open deck aluminum block, while a sleeved BP would still be a closed deck iron block.

I agree with the boring via sleeving. If the sleeving is done properly there shouldnt be any issues with it.

The fact being that increasing the displacement via bore will allow you to keep some of the engines desire to rev out like its stock but give you more power. I realize that longer stroke generally means more torque lower in the rpm range, but I prefer to have similar engine behavior to stock. once boosted the difference gap in power becomes more of a moot point.


If i were looking for more displacement for the right reasons, this would be my first choice vs a stroker or offset ground cranks. You could likely have someone sleeve it without it being the guys in the above link for cheaper. You would just have to do some leg work in sourcing some sleeves of the proper material and finding a shop thats both willing and competant enough to do this work.

Check out this thread on honda-tech to see how sleeving works in the open deck hondas.... its more or less the same process for all engines, but there would be less to worry about with the closed deck design.
Block Sleeving and parts fabrication - Honda-Tech

I kind of like the idea of bore, sleeve, and stroke personally. That is, if it were in my budget.

I feel like this would be glorious.

Did anyone else catch this?

FYI, you can't get the same pistons from Wiseco. All the pistons we sell are made for us to our specs, and the strokers in particular are unusual due to that low compression height.

Add up the same spec (ceramic tops, moly sides, uprated rings, oil ring support) and you'll discover there isn't an "FM tax". You guys have such a ridiculous view of our profit margins.

If someone comes up with a source for the crank that's as strong (they've been used in 800 hp engines) and less expensive, point me to it.

No one wants an 800hp crank when a 500hp crank would be more than sufficient.

Well, I know at least one person who would have been disappointed with a 500 hp crank...

Thanks for grouping us all together. Cause you know, we are all the same people here.

I remember Jkav's article about a long rod BP conversion on Edmunds.com using Milspec rods and JE pistons. Basically longer rods and shorter slugs. Not a stoker but altering piston speed and reducing side loads in the bore.

Long Rod BP Conversion And Nerdery - 1997 Mazda MX-5 Miata Long-Term Road Test

How about a shorter stroke for a high revving miata engine? Perhaps a 15k motor? :P

If the head would breathe, it would be fun :)

We can do a long-rod engine without too much difficulty by matching stroker rods to custom pistons. We've had at least one set of pistons made up to do it in the past. I don't really know what happened to them though. If someone else wanted to give it a try, it could be arranged.

So your saying the Weisco doesnt offer custom pistons to the public, Well just about every piston manufacturer does. And if you know what you want, you can ask them for a specific compression height, or whats the lowest you can go. Not every one needs flying miata to think for them.

Sav, obviously there are people that will pay big bucks for a specific power curve. I mean i payed big buck for top end power. Then bought nitrous for low end. My opinions greatly differ from yours because i do not care about fitting into a specific class.

And as far as sleeving goes, its all the same process, and they all can sink. I have seen v8 iron block sleeves sink, And i have seen tons of honda sleeves sink. There is always the possibility. Its not fun to chase blown head gaskets and overheating and oil mixing with coolant because of a sunk sleeve that you paid big bucks for. I think anyone with have a brain would avoid that headache.

Just been wondering how much longer stroke you might be able to get with stock pistons and crank. My '95 1.8l Roadster has I believe 9.0 comp pistons or slightly under.
Would lengthening the stroke a little mean the piston rising too much and mash the valves?? or is there a small useable clearance? or will the rings jump out the sleeves.
Reading JKav's blog he gains 7mm with the Mil-spec rods but uses specific JE pistons

your not gonna stroke it any significant amount without changing the piston compression height or the rod length. Maybe you could get away with offset grinding the crank .010" and running .010 under bearings. But you wouldnt feel a .01 stroke

Sure, design your own pistons and Wiseco will make them for you. Don't expect them to be any less expensive than ours though if you spec them out the same way. That's my point. And you can't just call up and ask for "Flyin' Miata stroker pistons", you will have to do some thinking.

It's interesting to note that Wiseco's off-the-shelf Miata pistons used to be quite a bit different than ours in small details such as the side profile of the piston. More piston rattle when cold. I think it's because they just stuck with their original design while we continued to evolve ours to improve. Even the stroker pistons have been through several running design changes over the years, from mild changes to increase valve clearance on VVT motors to fairly fundamental changes to the underside structure. When Wiseco went to the new castings, I think they updated a lot of their specs to match what we'd learned with ours. They're still decontented though.

Freaky, stroke comes from the crank. Unless you modify the stock crank by welding and grinding, the stroke won't change.

Or machining..

You'd have to be a special kind of stupid to machine a full 8mm out of the rod journal diameter in order to gain 4mm of stroke. If you're having someone like Castillo grind you a stroker crank without adding 4mm of material to the outer edge of the pin first, you're doing it very, very wrong.

I was using the term machining in place of keiths choice of word, grinding, which makes it sound much dodgier than it is.

Dann

I'd love to see you try cutting off 4mm from a hardened crank on the lathe.

I wouldnt try that at all Id give it to my machine shop to do, it sure wouldnt go to my grinder shop however.

The point of the post was that keiths post made it sound like a backyard operation with hand tools, where as it isnt, it was for the benefit of the poeple above me who clearly dont understand the process.

Offset crank grinding is a common practice, however taking 8mm out without doing anything else would not be recommended.

Last sentence again for the above people.

Dann

LOL a backyard operation eh? If you have one of these in your backyard please let me borrow it for a little while.

https://www.miataturbo.net/attachmen...ine=1372906539

I LOVE LOVE LOVE how often we talk about 500-600-800hp BP's on here and the parts required to build them when there is literally about a handful of BP's over 400....in the world

Signature material. If you go to m.net you'll see people listing all kinds of shit down to the dome light mods.

Ah, gotcha. In the US, pretty much any machining process that refers to the crankshaft is colloquially known as "grinding", no matter how elaborate the process. Rewelded, re-machined with an offset centerline, added 3mm to the pin diameter in the process? It's referred to as a "Crank regrind".

So the sleeves allow > 15 psi boost with the otherwise thin walls?

I take it too that they don't need to select a block for thick walls that don't punch the water jacket when bored to 85.5 mm like the 949 85.5 bore n/a build?

That's the idea. When you punch a BP to 85.5mm, the best you can do on wall clearance is ~0.110". That's borderline acceptable for an N/A build with an excellent radiator and oil cooler setup, but a FI setup really needs more wall thickness.

Yup, thought about it again with a clearer head and longer rods alone will just move the stroke higher up the cylinder. It does look like that it will increase compression but with stock pistons, at the risk of a collision.

what your saying is zero decking the motor by moving the stroke instead of decking the block. Like i said the most you might get is .010" more stroke, That would be if the pistons were .010" in the hole.

You could get away with elongating the rod by all of ~.015" before the squish becomes too tight. Decking the head is a much cheaper way to accomplish the same thing.

So the sleeving increases wall thickness by using space taken up by the water jacket?

That's a question for McCully, not me.

I have a receipt for my crank from Tennessee valley crank shop (I think that name is right). I think the crank work on a stock crank ran about 800 bucks. I'll try to pull the receipt and scan it tonight. They may be able to help you.

-Greer

What did you have done?

Bringing this back from the dead. Work was done by Crankshaft Specialist in Memphis TN, date was Feb '03.

Description on the work order is : 3.350 4CYL. Mazda, CK Out, Index, Lighten, STROKE 3MM. Work was 750. Shipping & handling was 33.00

I don't have an exact weight, but the below photo should give an idea.
https://www.miataturbo.net/attachmen...ine=1376274170

Work was good but they didn't turn the crank snout down to correct size. I ran my pulleys over to a machine shop and just enlarged the pulley the .00125 needed to make it all fit up right. I would have hit up the crank shop but this was 8 years after the fact (I'm the second owner of this setup).

-Greer

You run that crank yet? Curious how a regrind would work out for an n/a (no need for 800hp) build.

Am I reading this right? 3.35 liters? Would that still rev properly?

I am thinking that is the bore or stroke in inches.

And they added 3mm to the stroke by offset grinding the journals.

I would be interested in that sleeved block, longer rod, and shorter 85.5 pistons. I wonder if you could get a real 2.1 liter out of it? Might have to call Keith about those long rods for the stock crank.

your not going to get more than like 1970 cc with the 85.5 bore, so no more displacement without stroking too. I still don't like the idea of sleeving, look at how thin the webs between the cylinders are, now a normal sleeve is like .187 thick or so. that whole center web is made up of sleeve material.

They will machine out one bore and install the sleeve, then machine the adjacent bore and cut into the newly installed sleeve. I just don't trust it, to much to move and your reducing the coolant passages of the block. Maybe this would be fine to me if you were building a drag motor and filling the bottom of the block with hardblok and running methanol.

Oh if only we could get an aftermarket tall deck block with modified bores and water jackets, with room for a big swinging crank.

Now your talking, but if these k24 swaps take off I think the BP engine is a thing of the past.

The only reason I'd want to stick with a BP in a miata is in classes that require the stock block or block from the same make.

If the K swap kit isn't priced into the stratosphere than a K24a2 sounds like the best way to go.