OEM Piston Weight - Re-Balance?
 

Hi all,


I'm planning on rebuilding my 2013 FRS engine soon with all OEM parts except for pistons. I want to go with 13.5:1 compression and 87mm diameter to get a tiny bit more NA power with E85.


My question is: When I get aftermarket pistons that are a different weight from OEM (I cant find OEM piston weight info anywhere) will I have to re-balance the engine in any way?


Thanks,


Joe

No.

Why not swap out for stronger rods while everything's apart?

Not to mention lighter for maximum revs and NA goodness!

Lighter rods don't seem to be a thing for the FA20

No need for stronger rods when NA and apart from one fella with custom Ti con rods the OEMs are plenty light.



If anything maybe make sure the current or new OEM rods are all of equal weight and balanced since the new pistons will be.

Get some head work done while the heads are off. oversized valves, springs, port/polish etc... maybe even a cam. Rev her out to 7800 with the 13.5 compression, and get an ace 150 header for that top end. Maybe toss in some ITBs. you could Probably have The highest WHP non stroked NA FA20.

Just throw $15k at it. NBD

It is only money. :iono:

That way the rocker arms come out at higher velocity :party0030:

Why stop at $15k? Mortgage interest rates are at historic lows.

Probably not worth it unless you can address oiling issues. All that money just to watch a bearing spin before your first oil change.

Yup the only ones that seem to have it figured out are Element Tuning and after you add up all the stuff mentioned, you are well over $15k... Smarter to wait for the KMiata K24 swap in reality.

If you are rebuilding it to gain performance, why not spend a little extra and get it fully balanced regardless?

Element Tuning Pro Comp 13.5:1 NA Engine Build with Big Valve Heads $7363

$7362 - Element Tuning Pro Comp 13.5:1 NA Engine Build with Big Valve Heads
$1,495.00 - Ace 150 header
$2900 - Greddy ITB
$1250 - Piper Cams
$1645 - EcuTek w/t Flex fuel
$600 - Any oil cooler..


Total $15K+

I believe it was @86_IT who called ET about a big valve NA build using stock pistons. They told him it is not worth it NA. I'd imagine the NA pro comp build is if you are trying to maximize everything within a rule set.

Stock K24 with swap header and intake manifold with a tune is making 220-230whp.

:bonk::cheers:

I'd never do it, but it would be cool to see someone else do if they wanted max effort NA FA20 build.

worth it is very subjective. to me touching an FA engine without boost is a waste of time. but to others it might be exactly what they want.

bang for buck or more effective methods of achieving something aren't always what motivates someone to do it.

Sometimes doing something unique no one has done, or everyone says is not possible, not worth it, bad idea etc... is just the very reason someone might want to do it.

Sometimes the journey is more fun than the final destination.

Oh I agree. When I finish remodeling and selling my last rental I will be calling Pure and plunking down the 6k for harness and motec ecu for my K swap. I could easily sell the car as is and buy something that fits what I want more closely, but this car is mine :burnrubber: Plus if I wreak the car on track I can just buy a salvage title one and reuse those parts. Can't say I would be in the same position if I went out and bought an Elise or 4C.

Might want to wait until KMiata finished their kit. They plan to use a Halltech PNP kit $1800 and mate the K24 to the OEM transmission not that the S2000 transmission is that expensive used... In theory engine management alone $4k could be saved and dumped into a built K20 head. :thumbup:

I wouldn’t want to use our stock trans. It’s too flimsy and too far forward. I’d likely go E46 6 speed with the KMiata adapter. Will the Halltech retain full capability like the motec setup?

No idea man. We'll have to wait and see.

I spoke to Element about this same type of NA build, using either stock or JE pistons at stock 12.5:1 CR. They said the same thing, unless you want to build a motor for a ruleset. For me it's more about reliability, since my class's hp/wt ratio won't change. I just wanted a motor with the better oiling, upgraded bearings, valve springs, rods, rocker lockers, etc. etc.

I'm kinda purist with this car. At first I set out to prove it can be a front running car in GLTC, which at 200whp, I did. But the problem is you don't have the luxury of being able to make 215-225hp without a big money build, so then you can't detune to have a flat power curves, which is what all the K-swap miatas I race with have.

That said, I still really don't want to K-swap, simply because that's literally what everybody else is doing. But for guys who want big NA power (or FI), with a MUCH easier motor to work on, that you can buy from salvage yard for $700, it's hard to argue with the K24 swap, fo sho!