FormulaIntegra

If this is an easy search, I apologize in advance, but I've spent about 2 hours searching, and can't come up with anything at all.

Did a compression test on the ITA race car, and first pass, dry, cylinder #'s 1-4 were 160, 140, 127, and 60 psi, respectively.

Poured a little oil in each cylinder, and the wet pass was 240, 197, 190, and .... 60 psi.

Obviously there's a number of issues. I'm pulling the head tomorrow, but I'm guessing there's a valve issue on #4, and/or a head gasket issue. The decrease in pressure from one end to the other has got me puzzled.

With the way the pressures shot up across the board on the wet test, I'm figuring a re-ring and honing is in order as well. My biggest problem at the moment is trying to find new rings. The engine is a D16z6 overbored by 0.020", so 75.5mm. I didn't build the engine myself, so I'm just going on specs from the guy I bought it from, and don't have any exacts until I open it up and take measurements myself. I'm having a hell of a time, though, trying to find 75.5mm replacement rings on the internet. Can you guys point me in the right direction of where to look, or recommend a manufacturer or website?

If I search 75.5mm rings, I get a bunch of non-vehicle specific sets, and am not sure which ones would work. Searching by vehicle or engine gives me stock oem replacements, which won't work with the overbore. And there's a ton of ebay stuff that I'm less than enthusiastic about. Would rather buy from a reputable webstore. Any help will be appreciated.

TIA

Greyout

My guess is a majority of the guys in here avoid opening their motor as much as possible

Have you tried the engine machining & assembly forum?

jdblock

I'd do a visual check to see if rings are all you need, before ordering anything. For all you know the cylinder walls are FUBAR'd.

Machine shops can get rings, and they tend to stick with brands that work. Go talk to a shop and get a real idea about what you're getting into. Certain rings need a certain hone so they break-in correctly. Honing at home is one of the worse things you can do, it is easy to get wrong.

raceEG

Like jdblock mentions. I would check and start tallying up costs. It's one of those risk and reward scenarios when it comes to racing if you want the engine to be reliable, Once you open it up it's a rabbit hole (it won't just be rings that needs replacing or machining...) - it won't live a street engine life.

Have you looked at JEpistons for rings?

FormulaIntegra

I pulled the head and checked the sealing capability of the valves, and there wasn't much. Flipped it upside down and poured rubbing alcohol into the combustion chambers with each set of valves closed, and it came pouring into most of the ports, so it went to the machine shop to get a valve re-grind.

The guy at the machine shop said he didn't think there was enough oil residue in the combustion chambers to be too worried about the rings, so I'll install the head with a new head gasket and re-run the compression test this weekend, as well as do a leak down test. Hopefully, it was just the valves.

I did check JEPistons, and they do not carry anything for D series engines, or any Honda bores below 81.0mm, so they're a no go anyways.

raceEG

Ferrea Valves I believe would carry D16 valves.

gtpilot

https://www.ebay.com/p/?iid=35100593...pp=true&chn=ps

https://www.hondapartsdirect.com/oem...I9MiZhPWhvbmRh

FormulaIntegra

Got the head back from the machine shop. Seats and everything else were good, just needed a regrind on the valves themselves. They're all holding vacuum now.

Unfortunately, after putting the head back on the block, another compression test showed #4 will only pull 70psi (#1-3 are pulling between 172-182psi). Did a cold leakdown (I know you're supposed to do it hot, but I didn't want to refill all of the fluids only to have to dump them again), and #4 clearly was leaking into the crankcase. The dipstick "puffed" when I pulled it out and you could clearly feel air coming out of the hole. I'm not sure at this point if it's the cylinder walls, worn rings, or a broken ringland, but I've cancelled going to this weekend's race at Buttonwillow, and will spend the summer tearing apart both this engine and the bone stock one that was originally in the car to build/rebuild them up. My machinist will be able to tell if I need to rebore the block or if it will just require a re-hone.

gtpilot, both hondapartsdirect, as well as majestichonda list the 75.5mm factory pistons/rings, but they are discontinued parts. I've sourced a set of factory ones that are in singapore, but there's really not much factory stock left available. Per ITA rules, I can go aftermarket if sourcing stock parts is difficult, so long as the properties are same as stock, so same dome/dish, valve relief, etc. I have found Wiseco and JE Piston sets, but they are significantly more expensive that the Honda ones. It's going to be a fun summer in the garage.

jdblock

Have you checked Rockauto.com?

I'm not sure if I'd want to try and use their pistons in a race car, but the prices are much better than the performance aftermarket. They also have ring sets available if all you need is a hone.

FormulaIntegra

jdblock,

I did check Rockauto.com, and they only carry stock diameter (75mm) pistons for this engine. This engine is already bored to 75.5mm, and depending on my machinist's inspection, may need to go to 76mm (which are almost impossible to find in a stock dome/dish and valve relief configuration).

FormulaIntegra

UPDATE: So, after completely stripping the engine down, turns out the ringlands on the #4 pistons were completely destroyed, hence the complete lack of compression in #4. My machinist said with damage like that, the cylinder was definitely toast, so the the block got bored up to 0.040", we installed a block guard, and I bought a set of new Arias forged 76mm pistons. A bit more expensive of a repair than I was hoping, but such is life. Can't wait to get it all put back together and see the 1-2 HP increase with the new overbore. Thanks for the help and insight.