L8BRAKN

It's been a while since I posted. Last year I spun a rod bearing in cylinder number 2 due to oil starvation. From this point forward, I will be checking my oil every time I drive the car (which isn't often) and have 2 spare quarts in the trunk. The tech doing the build will be taking photos as the assembly evolves. So here's the overview of what we discovered on the tear down:

The number 2 con-rod bearing was spun and metal fragments we observed on the initial oil drain. No other damage was noted by the tech. The machine shop that inspected the block and head noted the amount play in the wrist pins were beyond factory spec. Also, they recommended replacing all exhaust valve seats and guides. I ended up going with all new OEM pistons and connecting rods which was pricey, but I didn't want to deal with an aftermarket fitment issues or having to sleeve the block by using different pistons. My block was honed to match OEM oversized pistons from Honda. The head has been freshened, all new bearings, rings, thrust washer, ARP head studs and con-rod bolts have been sourced. The crankshaft which showed minor scoring on #2 journal was welded and the entire crank was machined, journals matched and nitride treated. The work was performed by a very reputable machine shop and it too was pricey.

Here is the advice I'm seeking. I'm thinking about ordering another chain tensioner and timing chain. I'd like to reuse my oil pump, but have concern it may have been compromised with metal bits circulating in the oil for short time the motor was running after the bearing spun. I'm not on an unlimited budget with this build, so I'm trying to be smart about it. I basically have about $4K into parts and machine shop labor. The tear down and rebuild labor is additional. So now I'm flirting with $5K in costs and have already committed financially into it. If you were in a similar circumstance, what else would you add to the build? I'm in CA and don't want to mess with "hot smog" certs and other non-compliant headaches. If I were in another state, I would be driving around in a K-swapped car. Thank you CARB for not allowing this.......and many of your other dated policies that sometime defy logic.

Chibo

I guess I get to see the other side of the coin from what I'm taking (k-swap).

I've heard from a number of people about scored cam tower journals in higher mileage F20C motors, which was said to be from worn oil pumps. I'm unsure if this is entirely true, just throwing it out there in favor of playing it safe.
Timing chains are also noted to stretch.

L8BRAKN

This motor has 95K miles before the failure. I looked into a new OEM oil pump and they too are expensive. I don't know if there's a way to bench test my oil pump, but I'll ask my tech.

Hfreak

I would investigate the use of ARP studs, I have read that the OEM studs are the best option. Good luck with the build.

L8BRAKN

I sourced them through Science of Speed in Arizona, NSX and S2K specialists. For the head bolts, they seem to make sense and really can't imagine how that would be a disadvantage to the build. I did take the con rods back to the machine shop and had them torque the ARP fasteners and check the specs of the journals. Apparently ARP can require a different torque spec (presumably higher) and can affect the circumference geometry. Would there be a disadvantage to using ARP in the con rods? I spent over $300 for ARP hardware thinking it was a better way to go.

Billman250

ARP head studs cannot match the clamping power of the oem head bolts. I have seen them first hand allow combustion pressure into the cooling system.

Monitor the torque of a stock headbolt during torque-to-yield proceedure and you’ll understand why.

Chain and sprockets are the main wear items, and you’ll benefit the most by replacing them. You could do the guides, but they have nil effect on chain geometry compared to the chain and sprockets.

Oil pump can be taken apart and inspect for scoring of the housing.

Slowcrash_101

ARP head studs get torqued to 80ft lbs. Those 2 extra 90 degree turns + 23ft lbs on the stock bolts comes out to around 200ft lbs, or 2 1/2 times the torque applied to the head studs.

Why new rods and pistons? If the wrist pins are above clearance, replace the wrist pins. The rods weren't damaged only the crank and bearings. Did they use oversize pistons to match the oversize bores? And how bad were the bores that they required boring and honing?

The exhaust guides on the head are allowed a fair bit of play .009" is the service limit IIRC. Most shops would automatically put in new guides if they were that loose. What was wrong with the valve seats? We're they pitted, ovaled?

L8BRAKN

Responding to your first comment about ARP head bolts, is 80lbs torque less than OEM? The build literally just got off the ground so the ARP hardware hasn't been installed yet.

The number 2 con rod had damage and needed to be replaced. The machine shop advised going with new oversized pistons. I opted to replace all connecting rods as well. I tried to research this build with the limited time I have and seek advice from forums and various builders who know S2000. My conclusion was to stay OEM and by replacing all of the components, I effectively have about as close to a new engine as you can get.

The machine shop describe the exhaust valve seats as having been "hammered" which I think implies valves may have not been properly adjusted, had worn excessively and wouldn't seat/seal properly. This particular shop is very familiar with F20 and F22 motors and has seen their fair share. They are also do work for all the major franchise dealerships in Sacramento and are in demand. It took over a month to get my parts back from them.

My tech used to work for one of the major Honda dealerships and has all of his ASE certs for Honda. I could only go on what I was being told and put my trust in those doing the work. Neither the machine shop nor the tech gained any financial benefit from my parts order through Honda. My source of frustration with going through this process is attempting to gain facts and knowledge as the problem was diagnosed and how to go about resolving it properly. Opinions on how to fix varied greatly. Many shops I called didn't want to take on a rebuild. Looking back, I probably should have thrown in a used motor and sold the car. I do really like my car and plan on keeping it, so piece of mind and future resale value were part of my decision to go this route. I don't think you'll have many owners willing to go through this process and expense of rebuilding a motor. Those that are willing to do so, especially not in CA, could opt for aftermarket builds that don't meet California's rules and regs.

Billman250

ARP head studs are used in engines where their strength and clamping load surpasses the OEM hardware.

The S2000 is not one of them. This is 10 year old news.

They are not an upgrade in this engine, they are a downgrade

Anyone recommending them is going off of hearsay and does not have long-term experience with their longevity, or lack there of.

L8BRAKN

That's a bummer, so vendors pushing their product are in to make a sale........ I suppose you feel the same about the con rod bolts too?