PISTONS/BLOCKS

[TANTO]

Looking to follow the lines of MotorMouth93/Honcho/Mac Attack/Track Addict/Stuntman/Doc and others for my higher CR NA build. Thank you all. Purchased a couple of bad 3.2’s thru the years to upgrade my 92, one with a badly broken block(that I trashed) and one I still have with badly spun mains/badly damaged crank thrust surfaces. I understand this block could possibly be saved with the chevy small block mains/machining thicker thrust shims, but I’m not thrilled about that route, so when I got the chance to purchase a new 3.2 block at cost I jumped at it. While I could likely put my two sets of slightly used OE pistons in this block and save a BUNCH of money, of course I HAVE to get the CR up to 11.25 to 11.5. When Honda did the CFR thing, like so many likely thought, why CFR? Why not Nikosil at least? But we all know Honda can be a bit “thrifty” at times he-he. So my question is - what is the actual problem with having say JE pistons make me custom pistons a thou or so big and then hone? Are the CFR bores that bad? I do understand piston “slap” and that is not something a want to tolerate as I do take many short “sorties”. So If the CFR thing is bad please just hit me with it. I’ll have an adult beverage and move on to the sleeving train, just have to go thru the thought process. I see that Darton that does all kinds of Honda sleeving, but not the C32(?) Has block integrity been an issue? I understand that any mods we do involve some risks and since my car is a “toy” I will accept a lot of risk if needed. Certainly just about all of these “smallish” engines require sleeves that happily accomodate multiples of HP increases, just want to know what I’m getting into. Sleeve installer recommendation’s/cautions appreciated. Growing up in the home town of JEG’s drag folks, there were several excellent trusted machine shops. They are all gone. Since I “have” to do my own engine builds, I don’t feel like I can call Shad H for advice and I know many of you have been thru this. Thanks!

 

[MotorMouth93]

After many hours of research and phone calls to various shops and manufacturers I determined that the only viable option for using FRM cylinder walls are OEM pistons. I looked at what people have tried in other Honda FRM blocks (F series and H series) as well as what has been attempted with alusil blocks in German vehicles. I was actually trying to buy an OEM C32 block at one point before fully researching the subject, and ended up buying a used C30 block and having iron sleeves fitted.

What it ultimately boils down to is if you want aftermarket pistons and a reliable engine, you need iron sleeves.

The problem with dropping in JE/CP/Wiseco pistons is one of metallurgy. FRM cylinder walls are aluminum infused with fiber for strength, when you put an aluminum piston next to that and slide it up and down really fast it starts to gall even while well lubricated, and eventually destroys both the cylinder wall and the piston resulting in loss of ring seal and copious amounts of oil burning.

Honda got around this by plating the OEM piston skirts with iron, and the only aftermarket company offering anything like this is Mahle (but with mixed results it seems).

The real fun is there are companies out there claiming that just a thin piston skirt coating will allow you to run an aluminum piston in an aluminum bore, but that turned out to be false in all the real world examples I could find, the story typically was that you might get a few thousand miles out of the motor before it starts burning oil and losing compression. Then when you call them up they'll tell you you must have set the piston clearance incorrectly.

 

[Honcho]

John pretty much covered it above. The FRM is the problem and it doesn't make sense to machine that block when you can do the same thing to a less expensive 3.0. It's probably worth selling that new 3.2 block and OEM pistons to someone who wants to run the OEM setup and sleeving a used 3.0. My understanding from John is that the Toda pistons are the best you can buy for NA. The T3TEC units also are supposedly very good (and made by Toda). The US ones like Wiseco, JP and others are at a lower level of tech.

 

[MotorMouth93]

I wouldn't really say Toda are necessarily better or worse than anything else available...it sort of depends on the application.

You have to be careful with the Toda pistons for 3.2 blocks though, they call out the clearance for an aluminum block but if you ask them they'll tell you you need more if using iron sleeves. They actually intend for them to go in the FRM bores, but I was able to find exactly zero success stories of using Toda pistons in FRM blocks and a few horror stories so I decided not to do that. I believe it was an S2000 shop that told me they tried Toda pistons in an FRM S2000 block, the bores got torn up as you'd expect, and Toda blamed piston to wall clearance for their issues. You just can't expect a spray on coating thats 0.0003" thick to provide enough protection long term. I'm of the opinion that for built motors, stick with the tried and true ductile iron sleeves, they have worked really well for decades and will continue to work well, and leave the fancy materials to OEMs where they can build and torture test hundreds of the motors, and then they still screw it up. (See all the bore scoring issues early water cooled Porsche motors have, the BMW nikasil disasters, alusil scoring, etc.)

If I could do it again I would probably have just had Carrillo make me a custom set.

 

[TANTO]

I wouldn't really say Toda are necessarily better or worse than anything else available...it sort of depends on the application.

You have to be careful with the Toda pistons for 3.2 blocks though, they call out the clearance for an aluminum block but if you ask them they'll tell you you need more if using iron sleeves. They actually intend for them to go in the FRM bores, but I was able to find exactly zero success stories of using Toda pistons in FRM blocks and a few horror stories so I decided not to do that. I believe it was an S2000 shop that told me they tried Toda pistons in an FRM S2000 block, the bores got torn up as you'd expect, and Toda blamed piston to wall clearance for their issues. You just can't expect a spray on coating thats 0.0003" thick to provide enough protection long term. I'm of the opinion that for built motors, stick with the tried and true ductile iron sleeves, they have worked really well for decades and will continue to work well, and leave the fancy materials to OEMs where they can build and torture test hundreds of the motors, and then they still screw it up. (See all the bore scoring issues early water cooled Porsche motors have, the BMW nikasil disasters, alusil scoring, etc.)

If I could do it again I would probably have just had Carrillo make me a custom set.

I totally missed the iron piston coating thing which seems to be the critical issue making the OE 3.2 setup acceptable. Makes sense, i do remember when you could get a sexy bmw 850 for almost nothing. I certainly wouldn't be comfortable relying on a piston coating. While i'm sure we are all here huge aluminum fans - iron is still required. Where would you rather live? the earth (iron) or the moon (aluminum)? I digress. Thanks for the education! I'll draft another post on sleeves after i sober up!

 

[Honcho]

I wouldn't really say Toda are necessarily better or worse than anything else available...it sort of depends on the application.

You have to be careful with the Toda pistons for 3.2 blocks though, they call out the clearance for an aluminum block but if you ask them they'll tell you you need more if using iron sleeves. They actually intend for them to go in the FRM bores, but I was able to find exactly zero success stories of using Toda pistons in FRM blocks and a few horror stories so I decided not to do that. I believe it was an S2000 shop that told me they tried Toda pistons in an FRM S2000 block, the bores got torn up as you'd expect, and Toda blamed piston to wall clearance for their issues. You just can't expect a spray on coating thats 0.0003" thick to provide enough protection long term. I'm of the opinion that for built motors, stick with the tried and true ductile iron sleeves, they have worked really well for decades and will continue to work well, and leave the fancy materials to OEMs where they can build and torture test hundreds of the motors, and then they still screw it up. (See all the bore scoring issues early water cooled Porsche motors have, the BMW nikasil disasters, alusil scoring, etc.)

If I could do it again I would probably have just had Carrillo make me a custom set.

Isn't the other nice thing about Toda that they are 4032 alloy? NA friendly for less expansion/slap?