Miata Gets a MARUHA STROKER Crankshaft From Japan!

I just can't put things back together the same way they came apart. The quest for power under the curve continues. Also slight correction, when I spoke about rod/main bearing clearances I should have been speaking in "ten thousandths" rather than "thousandths." Another slight correction - when you bore up, you do actually gain a small amount of compression rather than losing it. You're pulling in more air to begin with (left side of the ratio i.e. "9:1") and compressing it down into nearly the same space. The combustion chamber in the head remains the same size, but technically the overall area where the air is compressed grows slightly with bore-up due to larger head gasket and volume between the deck and piston (right side of the ratio) so the bump in compression is very small, usually about 0.1 or less. Changing the stroke from 85mm to 87mm however, raises compression by about 1 full point. So this thing is going to be REAL rowdy.

My requested specs:
Rod = 0.0020 - 0.0022"
Main = 0.0018 - 0.0020"
Thrust 0.0060 - 0.0090"
Top ring = 0.0170"
Second Ring = 0.0190"
PTW = 0.0030"

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0:00 Intro
0:53 Unboxing
3:08 Raising Displacement On BP's
5:19 Maruha Crank vs. Stock
5:53 Machine Shop Plan & New Parts
9:00 Build Specs/Clearances For Rebuild
12:50 I Get Peer Pressured Into Sending It Even More

[TheCarPassionChannel]

Slight corrections to the video - when I spoke about rod/main bearing clearances I should have been speaking in "ten thousandths" rather than "thousandths."

My requested specs:
Rod = 0.0020 - 0.0022"
Main = 0.0018 - 0.0020"
Thrust 0.0060 - 0.0090"
Top ring = 0.0170"
Second Ring = 0.0190"
PTW = 0.0030"

Another slight correction - when you bore up, you do actually gain a small amount of compression rather than losing it. You're pulling in more air to begin with (left side of the ratio i.e. the "9" in "9:1 compression") and compressing it down into *nearly* the same space. The combustion chamber in the head remains the same size, but technically the overall volume where the air is compressed grows slightly with bore-up due to larger head gasket and increased volume between the deck and top piston ring (right side of the ratio, i.e. the "1" in "9:1 compression") so the bump in compression is very small, usually about 0.1 or less. Changing the stroke from 85mm to 87mm however, raises compression by about 1 full point. So this thing is going to be REAL rowdy.

[hashematassi]

“It’s going to be tuned for a bit less power than the last set up…”

~ 2 months later ~

“Oh my God boys we just made 600 whp. The turbo is on fire but I’m going to leave it as is for the street cred.”

Love you Krayg🙏🏼❤️

[mmavcanuck]

Glad to see more regular miata dad videos again. You make the YouTube car community better!

[MidnightMiata]

I definitely endorse the high comp pistons! I'm running 10.5:1 in my 1.6 with a GTX2860R and it runs fantastic on pump 93oct. You'll definitely like the broad powerband it gives!

[mtbiata]

LMAO I literally called you out in the last video for that first statement (0:00)! 😂 I knew you couldn't stop yourself Greg and we love you for it!

[andrewjutras]

I honestly think backing it down a notch is what's best for the car. You're basically building an even more bulletproof version of it's previous state, and you should be able to enjoy driving the car. Keep it in a safe, reliable power range, and enjoy having another pair of jackstands freed up for whatever your next project is :)

[daniel]

In my opinion keep it on the safer side of spec. Dyno queens are cool and all but I think you should enjoy driving it more. We need to see this thing embarrass some v8’s asap 👌

[codegreen]

Bofi are so great, called up and spoke with the guy who does their youtube videos about a frankenstein engine build, was happy to chat with me and super helpful! Love that you're using a repping them, peace from the UK ✌🏻

[TheeCrazyblackman]

Love being surprised by the new details you give us on builds!

[TwinTurbo]

I appreciate you, Greg. Living vicariously through you right, now
You gotta say no to peer pressure (sometimes) Send it, bro!!!

[ldsiverling]

Maruha makes some of the best stuff. I have their extended top hats for my coilovers.

[tehpillemannerator]

Craige, you rock. What I would really love to see someday would be a "budget engine rebuild from start to finish". Toughen it up where reasonable and going the budget route where ever possible. What to do yourself and what an engine shop has to do. I know you've made great engine rebuild videos before but with the goal of extreme power. Most people run around 250 whp and would love to be on the safer side engine wise :)

[richardpeterson]

Nice pic in the Flyin' Miata flyer that came in the mail today! It seems they really enjoy your support in your channel.

[someoneelse]

We love you Buddy. Thanks for letting us live vicariously through your Miata lifestyle.

[dil]

High compression pistons seem to make more sense in the pursuit of a broad power band. Mazda's cars these days are all running ridiculous compression and they have great low to midrange torque for being small 4 cylinders. Plus, making more power by improving thermal efficiency seems like a win-win to me.

[RyanRoadReaper]

This has got to be one of the fastest street Miata's out there on YouTube

[jasonwassman]

Picked up my car from AED and saw your bundle of goodies ready for the machine shop, very nice stuff, glad to see what you do with it!

[Miatafication]

Awesome channel and you pushing to the limit videos are teaching me a lot 👍 thank you for your time

[ludesit]

High compression for the win, anything to get that turbo to MBT as fast as possible.I still wager you need some sort of advanced traction control system that can properly manage wheel slip. Otherwise big power numbers do you no good. Not sure what you have access to in the miata world, but there is some nice stuff out there that can read front and rear wheel speeds and pull timing and boost to allow you to reach a set wheel slip percentage, 10% seems to be optimal for best acceleration.

Anyhoo its been fun following along the build and I'm about to dive head first into building a high response RB26 myself. I've got some tricks up my sleeve since RBs are super lazy on the low end. I'm hoping for a pretty flat torque curve from 3500 to 8500 with a turbo capable of 650 horse. We'll see where I get.

[Squirrel]

Go with the 84mm and higher comp pistons route! I'm not a pro engine builder, but I'd rather have more meat in the sleeve on a boosted car. The more on the major thrust side the better. That's why anyone sane who builds 85mm> BP motors sonic tests theirs blocks.

Weisco's 84mm "10:1" pistons have a 7cc dome on them FYI. I have a set waiting to be put into a very similar build to yours (84mm, same pistons, but NA for the time being) I've yet to cc them to figure out the exact dome size, but I'll do that if you're interested.

Anyway, I'd first figure out your piston to valve clearance on your head before you shave it. Then get fancy and incorporate all the math (cc your chambers, figure out theoretical piston to deck height, etc) and then shave your head what you can (you should have enough...), or until you get to a static compression of 10.5:1 or 11:1.

Obviously you'll have to live in ethanol land permanently with that dynamic compression ratio.

Looking forward to the build!!