"FRM sleeves are bad." Why? Someone please explain this.

[cb7 calling]

I believe it's the rings. I don't know because I don't rebuild engines but I'm talking about stock internals with frm vs stock with iron sleeves. The frm sleeves seem to burn oil more often. Even the Toyota motors with frm have the same issue. The Toyota frm is different than honda but still it's too hard on the rings.

My question to the engineers is are iron sleeves really the weak point in these motors to begin with? Why change? I don't see a bunch of Hondas with cracked sleeves in the junk yard, I'm guessing I see bad bearings if it's a five speed. It's an auto bad tranny 90 percent of the time. How about frm gears in those autotragic slush boxes you build?

[JDMDriver]

I wouldn't really say it's a new design... FRM sleeves were being used by Honda in 1990! It's only one year newer than VTEC (which has been largely embraced by most Honda enthusiasts.)

Not new design but new concept and therefore less grasp in dealing with FRM. FRM knowledge dissemination is relatively low, let alone the gain in common knowledge in dealing with them.

Those individuals being surprised with the nature of FRM end up having a bad experience and result in a lot of negativity because of the complexities it gives and barriers it poses with their costs blow outs, time delay and other inconveniences or trial and error made.

There were a few that posed the "FRM causes oil consumption" argument... which I normally argue with the concept of engine health and maintenance (I've never noticed any significant oil consumption in my H22A).

Higher oil consumption is due to an already worn piston ring allowing more oil to by pass the rings. This would happen after only after hundreds of thousands of kms its not like FRM causes premature wear and would wear out before the first hundred thousand.

FRM was first introduced on the Prelude from my knowledge (3rd Gen). From what I gather FRM is not as good from the stand point that as a unit the engine with FRM experiences earlier worn piston ring situation than the non FRM counterpart.

However some argue this is the intention so as to only wear out the piston ring and not share the wear and tear with the cylinder wall so that the piston and rings are the only parts need replacing making easier overhauls. A piston ring change a bit earlier than the Non FRM engine but much simpler, less risk and therefore easier. Arguable because alot simpler and easier can be from a mechanics point of view not the hip pocket of the owner who can only see themselves paying for an engine overhaul earlier. Even then from a mechanics point of view of being easier can be argued as not any easier. A mechanic lacking knowledge on FRM handling may find it more harder and confusing to deal with and expensive with lost time = lost money gaining knowledge or worse paying for ruining an engine by honing it too much or with the wrong equipment.

Some have said replacing only the piston and rings without honing is possible on these FRM engines (well the Prelude ones anyway) and can last for another couple of hundred thousand with no worries at all.

How true that is I cannot say from experience. It however holds some truth in principle, because if was applied to brakes and rotors (rotors being the cylinder and pads being the rings), softer pads mean more frequent changing but no machining of the rotors required. Harder pads last longer but causes more scoring to the rotors. I follow this rule and have yet to machine my rotors on all my vehicles.

One person did mention an interesting point, though... in regards to the H22A specifically. He said that the H22A's FRM sleeve material is thinner than the material found in other "better" FRM-equipped engines, such as the engines found in the NSX and S2000. I'm not sure how much merit there is to that, seeing as I've never even attempted to hone or bore an FRM sleeve... but it's interesting nonetheless.

Sounds right since the less sporting vehicles would naturally see less action and therefore require less durability.

To my knowledge, FRM can't really be bored, and it can only be honed very lightly... but it is also not supposed to become worn out with proper use like iron sleeves do. If it doesn't wear down like iron, then I'd have to argue that the thickness isn't an issue.

I say it still does wear out hence "can be honed very lightly" to remove the very light scratches (wear) it can experience.

CyborgGT touched on the only TRUE weakness that I recognize in FRM sleeves... the fact that if they get damaged, they're pretty much shot. Score up a sleeve with a damaged piston, and there's no bringing it back.

I imagine that will be after several piston and ring changes under normal circumstances.

Each piston ring change can last 200,000 miles (say 15 to 20 years at a time). FRM engines can go through the factory rings with no damage to the FRM. At minimum the FRM can realistically last a 3rd and even 4th set no problem without honing.

If each piston ring change can last 200,000 miles (15 or 20 years) a total of 4 piston ring changes is at least 800,000 miles (60 to 80 years) and for the most part the car or the owner will not see the end of that.

In my opinion the FRM's are destroyed by being thrown out not knowing it can be restored to factory by a mere piston ring changes, the vehicle gets into an accident, or the whole vehicle rusts away and the engine thrown out with the car or the engine experiences severe abuse that it is not worn out but destroyed through other means (lack of coolant maintenance, lack of oil, not using proper oil viscosity, too long between maintenance intervals etc).

Under normal conditions and proper maintenance these FRM engine blocks should last a lifetime with only cylinder rings being changed to bring it back to factory each time.

[Joey GT-R]

One factory piston that could be an option is the piston from an F22C. The F20C piston would work as well but it has a slightly larger dome to get the same 11.0:1 compression ratio from a much shorter stroke. Anyway, the F22C piston is FRM-compatible, it has a 30mm compression height(1mm shorter than the H22A), it's an 87mm bore and it's factory forged. The downfall to this piston is that it uses a 23mm wrist pin as opposed to a 22mm pin used by all other F/H/K-series pistons.

You told me this a year or so ago. What was the solution on the 23mm wrist pin, machining the rod to accept it?

This thread has me thinking as I rebuild my spare H22 block for next summer.

There is a Porsche shop with rumors of another shop now with the capabilities that has built some pretty potent 911s. I have reached out to them in the past and they were quite cocky about doing the job(Euro guys for ya).

This makes me want to keep my FRM Cylinders and prove once and for all these can last a long time.