Greetings !

As a short backstory back in 2019 the engine of my -00 AP1 started to make really nasty knocking noise - turned out the engine had ran very dry.
Since then it's been sitting in a garage waiting patiently for me to build up motivation and deal with the fact ill have to probably pour 5k€ into the rebuild.
Now i've finally pulled out and disassembled the engine, first time I've gone past the valve cover in disassembly - so I'm quite a virgin here and seeking for advice on the rebuild.

Disassembly reveled heavy damage on 2 of the pistons, deeply scratched cylinder walls and one heavily grinded down connecting rod bearing - photos at the end of the post. Rest of the engine seems fine.
From the research Ive done i have figured out the cylinder wall is probably beyond fixing, as the FRM coating is quite thin. So as for cylinder walls im going to go the route of stock diameter darton dry sleeves, which i have already ordered.

Pistons
Next i need to figure out which pistons to order, power wise im keeping the engine stock and just trying to build up the engine to stock standard.
There are CP forged pistons, but they don't seem to have stock compression rate, closest one seems to be 12.5 - does that matter?
Mahle ones say "For Use In Factory FRM (Fiber Reinforced Matrix) Cylinders Only" on some sites, meanings they are no go with sleeves?
Wiseco seems to have 11.1 and 11.4 compression ratio pistons, thats more than stock - but again does that matter?
Wössner has 11.7 compression rate pistons, again is that a problem?
Is there any other choice i should consider? Any advice here is appreciated, as i would like to place the order soon.

And can i use my stock connecting rods with these pistons if they are okay tolerance wise?

Parts
For which of the replacement parts should i try to go oem honda and which should i replace with aftermarket ones? i suppose ill need at least following parts;
Block gasket kit
Head gasket kit
Head bolts
Connecting rod bolts
Crankshaft bearings
Injectors flow test and gasket kit
Coils
Clutch pack with thrust bearing
Chain
Engine mounts
Intake valves (managed to ruin mine by cleaning the carbon with phosphoric acid )
Valve stem seals
TDC2 sensor (ruined while pulling out the engine with tranny - not a good idea)

Anything else i might need..?
Recommendation for an European parts site? (not UK due to customs)


Head damage
Not sure how the cylinders and pistons of cylinders 2. and 4. got ****ed up that badly (photos below), perhaps an object / parts got into the intake, but it also left some damage on the heads combustion chamber.
How bad does this damage look, and is there anything i can do to save the head?

Any advice is greatly appreciated!

 

Since you want to do a stock rebuild you should use OEM parts wherever possible. No reason reducing reliability by going aftermarket without getting extra power for it in return.
JDM F20C had 11.7:1 compression and that still runs fine on EUDM ECU and RON98 fuel, 12.5:1 is pushing it a little bit more but anything below 11.7:1 is definitely fine.

 

... higher compression can lead to pre-ignition, knock. Requires higher octane fuel to prevent. Engine will pull timing when knock sensed, which greatly reduces power in our engines.

So yeah, what he said. 11.7 ok (use high octane fuel, which should be doing anyway with these motors), higher than that for race car race fuel, for street driven stock build not so much.

You know about matching bearings to motor, right? These engines were habd assembled. Tech would measure crank and rods, crank and block, and select bearing sizes for each location. Each rod, each main. If crank isn't being machined, use bearing sizes factory used. If crank is machined, will have to try different bearing sizes in each location, carefully using plastigauge to find right bearing for each spot. That means buying lots of the different bearing sizes, and having a bunch left over.

 

Based on postings here your engine is likely non-repairable. Not sure where you can find a used engine in Finland though.

-- Chuck

 

Needs another crank,head,oil pump. ad Infinitum
Suggest costing it up,thats going to be a lot of £s and compare price with another engine.

 

For the money and time it costs I would k swap at this point. Good f20s are going for $6k usd plus labor you're looking at around 10k. Costs roughly the same to k swap.

 

Thank you! will go with the 11.7 probably; just have to choose the brand
Didin't know about the bearing matching. Will have the crank checked by a shop, dunno yet if it has to be machined; thanks!

Wouldnt really want to go the way of replacing with another used engine of which condition i cannot be sure about, as it would indeed probably have to be shipped from Germany or UK.
Im a fish on a dry land here, but the block can probably be fixed by just sleeving and new pistons. Of course might need a new crank also, but already have a source for that.
I would image the head can also be made usable by grinding the damaged surface by a professional? or a bare head without internals shouldn't be too expensive if i manage to score on? everything else on the head is fine.

If the head can be fixed by lightly grinding the surface, should all of the 4 cylinders be done? by intuition i would imagine ground up chambers would have slightly smaller compression ratio, thus the energy from the explosion in the chamber is not symmetrical with the non-ground chambers and that may cause fatigue damage in long term? of course the difference might be so marginal that it does not really matter in the real life.


Wanna keep it original for the appreciation potential


Thank you for all the replies!

 

A new used engine with kind of unknown history is probably going to be way more reliable than if you are trying to rebuild this.
Even expert shops have failed numerous times when building these engines, so keep that in mind before ordering more parts.
If you do go ahead and rebuild make sure you really trust the machine shop doing the work and read up on everything before hand.
For OEM parts from EU check https://www.a4h-tech.com/en and https://www.akr-performance.com
Some parts are probably a lot cheaper from US or Japan though, even with shipping and taxes included.

 

If you machine the cylinder head or top of the block you'll bugger the valve chain geometry and the cams and valves won't align properly. These engines are totally reliable until they break after which they rarely experience a successful rebuild.

-- Chuck

 

I would not buy a sleeved S2000.
10-20k miles max if your lucky then another cylinder bore and new pistons and another £k? expense
Cranks can not be re-ground on an S2000.
Heads can not be skimmed due to TCT issues.
Non Honda Pistons dont fit Honda rods,so allow for new con rods<pin size difference >
Good luck on your build