OEM Piston Ring Refresh on 1.8 Engine Build?
 

Hi all,

I'm preparing to start an engine build on a 2001 1.8 VVT engine and am looking for a bit of advice, here are the intended engine parts:

-Manley H-Beam Rods
-ACL main bearings
-ACL rod bearings
-ACL thrust bearings
-ARP head studs
-ARP main studs
-Stock pistons
-Stock rings

My question is, while building the engine is it worth refreshing the piston rings with a new set of OEM Mazda rings? I have no intention on using anything other than OEM pistons but I'm curious whether or not its worth changing the rings while the motor is apart; primarily for the sake of reliability. For reference, the engine will be used in a 250-275whp turbo build. Any advice is appreciated.

I would absolutely not reuse rings if the pistons come out of the cylinders. Buy new rings for when you put the motor back together.

Also no need for main studs, when using stock pistons

Gotcha, I'll order a new set of OEM rings, I figured this would be the obvious way to go but just wanted a second opinion.

I know it's probably not necessary but given the small cost of new studs I'd rather just replace them while the crank is out.

for FI applications on pump gas, i would find a good used set of NA OEM pistons. they have lower compression 9.0 NA VS 10.0 NB2. this will make turbo tuning easier and higher ceiling for detonation.

i am running 94 oem pistons with Mahle rings and untouched VVT head pushing 309whp at 17psi on a 6258 on florida 93 pump gas.

I dont think i could achieve this on stock NB2 10.0 CR pistons.

i do apologize if this seems as a thread jack but i just had a simple quick question for

@borka . I am planning a build in the future and I am trying to decide on if I should reuse my oem bp4w pistons (as long as they are good when build time comes). My goal would be 300hp at the max because I read that once over 300hp things get expensive. This would be a street build with maybe some short tracking here and there and most importantly this would be strictly e85 gas. With that being said I think I can get away with nb1 pistons and just re ring them do you think? I like the idea of a budget rod only build with e85 and probably refresh the head. Again sorry to sidetrack thread.

Also, ACL doesn't make a thrust washer for the NB2. You want an OEM replacement, of course 01-05.

If running strictly e85 the higher compressor pistons will be better.

thank you for the advice and yeah that is what I am seeing when researching this the last couple of days. It may be a good idea to try to build a vvt engine instead I think because the higher compression. Or maybe skim my bp4 head. I'm still reading up on what is the best route to take on an e85 build/ what I can do to get more compression without having to spend money on pistons. I think oe pistons would be fine for my goals.

I don’t think anyone here trying for a 300rwhp build is going to say higher compression is the easy button. Per several prior comments from Emilio, the only high power/E85 platform that seems to like compression is Rotrex, but it’s incredibly different from the older Eaton MP62 technology. Hell, the MP62 wasn’t even the most efficient blower when the kit was available - just the most widely available. You cannot spin a blower, nor a turbo to infinity. It would be a better use of time and money to start with the proper platform. A bigger blower, or a bigger turbo.

What? Please point to where Emilio said that. I don't see how the form of forced induction makes any difference. All else being equal a higher compression engine will be better everywhere. If you aren't knock limited there is no downside.

If I was building a 300 whp Miata with aftermarket pistons and e85 it would be 13:1+.

I am still reading up on building an ideal engine for myself but most of the literature i see in regards to e85 builds says that compression is your friend and that you can most likely use stock pistons for 300hp if you wanted. I am also seeing people claim the roots blowers love compression and this is why I am thinking about higher compression at least more than what I should have currently in my bp4w. On a side note I'm heavily considering just trying to sell my blower and convert to a turbo setup since the cost and parts I need to get 300 out of a blower is significantly more vs if I get a decent turbo build.

To clarify what I wrote

Per our experience with a variety of different forced induction methods, Rotrexes seem to tolerate the highest compression and indeed seemed to benefit from it with enough octane. E85 Is roughly equivalent to 112 AKI.

That said, F1 and WRC both run very high static compression with turbos. But yes on something decidedly lower tech like a turbo BP Miata, it's generally more effective to increase boost at it and manage det by dropping static compression.

Deviate made 300whp on corn, C30-74 @9.5psi and 10.5:1 with Tomei cams and a built 1.9L BP6D