The honing instructions from Honda for the F20C don't list any 'black magic'. Just a specific machine with special stones.

The machine is actually quite common, a Sunnen CV-616. It's much older and you can likely find a machine shop that has one (if not, call small machine shops and ask if they know anyone with a CV-616). The CK-21 might work as it's 'just a newer version' I'm told, but not sure what stones you'd want to run on them. Get the mandrel/toolholder part number, call Sunnen technical department and ask for equivalent stones for it.

The stones that Honda calls for, 'GC-600-J', aren't really listed anywhere. Inference tells us it's a 600 grit stone, and honing weird composites (back in 1999) like this probably rules out diamonds (and GC likely stands for 'green silicon carbide' anyways).

Matching parts? C30-C05. Will only fit on a CV-616 fit with the CK-3045 "Master Holder" kit. These should be functionally identical to the stones Honda calls for in their service manual.

Currently evaluating the condition of my motor, but keeping the FRM liners is absolutely possible as H22 boys have been doing it for years. I'm not sure how effective this honing method actually is, but if Honda was willing to warranty engines rebuilt like this, I'd imagine it isn't bad.

I'd appreciate any feedback. Could save a lot of blocks if this method is effective. Attached is the honing instructions from the factory service manual.

 

When the stones were available it wasn't a big deal. This has been discussed quite a lot over the last decade. We have more or less moved on to other methods of recycling these blocks now.

 

You use a diamond hone stone now. You rough out at 400 grit, then finish with 600. You need a very strong very expensive set of stones to hone the block. Honing a normal engine would run you ~$120 tops, these engines expect to pay ~$450-500 for a good hone with a torque plate.

 

honing is not going to fix scored cylinders, which is the issue that has ruined many of these engines. There is an option now for that but it is not cheap. Fix the bores, recoat with NSC, then build. Charper offers that service if interested.

 

You can hone out a cylinder .125 mm safely. The FRM coating is .25mm, so if the vertical scores don't catch a nail(around .125mm) you can hone the block to like new. The question becomes, is it worth doing? Considering the effort and cost, a replacement engine used to be an easy alternative. As costs surge and availability becomes scarce, then other options start to make more sense.

Its now to the point that buying a used transmission and rebuilding have hit a crossover point.

I remember 10 years ago you could get a used diff for $500 impossible now.

 

Yep but that is it. So for a refresh sure. But if you have any issues related to the bores that prompted tearing it down, you likely are dealing with scoring that cannot be repaired by honing alone. I dont think there has ever been much concern about honing for a refresh if done properly, it is significant scoring that tends to be the thing that has traditionally made them paperweights. But hopefully with people doing the NSC coating (about $2k just for that last I heard) and Honda maybe starting to build parts again we will have more options. Likely not cheap ones but options nonetheless

 

No wonder many folks end up going with a K-Swap rather than the cost of a rebuild and the prices that entails. I know it isn't quite the same as the S2K motor, but do what you can with the money you have.

 

Especially for track cars. The Kwap is spendy up front but the idea is that if you blow up a motor, your options are better to replace the K24

 

These days, you just send the block to Charpers to get it NSC treated. It's expensive as shit but better than FRM, and at least you know the integrity of the block. It can also apparently be done indefinitely. Urge uses Charpers, too. You just need a good crank which is the hard part. No fixing a scored crank, unfortunately.

 

I called Millennium Coatings and they quoted me $1,604 before shipping to Nikasil plate and bore the F20C. Nikasil plated sleeves are $3,700.