Hi Guys so I have a 1999 miata (with nb2 nose) and I have happened upon another 99 motor to build. It has overheated and needs a top end rebuild but since its a second motor I planed to strip it all the way down to the crank and do every bearing and gasket on the motor. So my question to you induction guys is what's the best rod and piston combo I've heard a lot
of chatter about running over bore sizing causes damage to cyl walls and piston slapping which I'm trying to avoid as it will be my daily still. Also note I plan to slap a m45 on the motor with a IC and MS and push around 11psi hoping with a built motor and SC to push 220whp probably less. But I digress, if anyone has any experience with the rod and pistons on a daily miata some advice would be appreciated. Really any daily boosted mods or need to knows frankly.
Thanks, Paul

 

Where did you hear this chatter?

Surely it wasn't here on this site.

 

BRB getting my spoon. Open wide

 

it was on a post here and then some local boosted ls guys and even a couple mustang guys. I will admit that the whole concept of over sizing to standard pistons and the perks to them and disadvantages get lost in translation to me. I gather compression rates and what have you but the over boring aspect I don't understand why or why not that would be an issue if measured and done right with quality parts

 

What have your preliminary searches on this site shown?

 

you spoon feed me the info, and I'll then tell you

 

ls guys tell me it can cause a piston slap

the forum here mentioned something about strain on the pins but I do not exactly follow as the thread seemed to be between people have better knowledge and where more arguing about brands and not so much the bore size.

Mustang people said something about getting quality piston rings which I planned to buy the same brand as the piston. Wisco or eagle or st. Thought it would probably be best to keep within the brand for best results.

 

rotary guys tell me to replace my apex seals

I think they mean muffler bearings cause my engine is clearly a boxer

 

no need to be condescending the whole idea is to ask questions. Sorry if they are dumb to you I admit my ignorance and I'm just relaying the info I've been told.

 

Why would anyone build an engine for an m45?

 

more Na power is why I am building it plus I am running a m45 for now until I get a second car and can find a mp62. Yet to find one and you can grab a m45 for so cheap I planned to toss one on for giggles while I waited

 

also have to take the top End off so I planned to go ahead and do the bottom too. I have everything sorted besides sizing on the pistons and what brands. Lots of back and forth arguing it seems across forums and really just wanted some direct input instead of reading people's conversations confused as hell most of the time. Probably end up running standard sizing to be safe since I can't really get a clear answer if it over sizing has any real negative effects

 

Show me the threads you've read on this site, Miataturbo, about pistons and bore. Not GM, Mustang, Nissan, Honda, Nabisco, VWVortex, Opel hearsay.

What have you read here. Just to understand where you've looked for your information.

 

I wont spoon feed paul but I would recommend you take the subtle hints psyber is giving you and use the search funtion of the website. Each section on the site has stickies. Maybe go to the section you think applies and find a sticky. Might just have what you are looking for. I love slapping pistons when they make boost for me. Also do you have any cats?

 

what gave you that idea?

 

In the build section, there are several cars that are daily driver capable, perhaps you can see if there's something there that matches your goals and what that setup entailed.

 

TBH most cars here have piston slap, but thats just the gaggle of owners.

 

what is this piston slap that you all speak of?

 

I don't know if I have that much piston slap.

 

A M45 will never hit more then 200whp. I would not spend any money on building a motor if planning on using that long term. Even with a MP62, I would be hard pressed to build a motor.