13173

So last week I started filing the rings for my K24 engine that I am putting together. The rings are CP Piston rings. I used their spec sheet to figure out what I should gap the rings. Most that have built an engine know the formula. They suggested a wall clearance of .0035" for the pistons. I went with a P2W clearance of .0040" after doing some research and talking to a few experienced engine builders that had more experience with CP Pistons than me.

So here is the deal, from my calculations my top ring gap should have been somewhere around .022 - .024" and the second ring gap should have been around .024 - .026" as per my calculations using the CP specs. I am using the 87.5mm shelf pistons in the K24A1 stock sleeves. The engine will get pushed to whatever it can hold at some point, but will be more of a street engine and not one that is going to be raced on a regular basis. It will also be ran on gasoline since ethanol is not really an option for me. This is what my ring gaps looked like with the rings placed approximately 1" into the bore using the piston to level them out in the cylinder. Some rings were simply placed into the bore and not filed, others were slightly filed to achieve a wider end gap.

cylinder 1 = .025" for the top ring and .028" for the 2nd ring
cylinder 2 = .024" for the top ring and .027" for the 2nd ring
cylinder 3 = .023" for the top ring and .025" for the 2nd ring
cylinder 4 = .027" for the top ring and .030" for the 2nd ring

From my research, these gaps should probably be alright considering they will be in a turbocharged gasoline engine. They seem to be a little on the loose side, but should work I think. However, I am concerned that I will get too much blow-by. I have sent CP an email and should hear something maybe tomorrow. I did also talk to an experienced engine builder. He said that they sounded too loose for stock sleeves, but might work just fine for me. He does not like to run them that loose, and said that I may need a new set of rings.

What do you guys think?

turbohatch96y7

iTrader: (15)

Why is each cylinder a different ring gap? The gaps seem really loose.

wantboost

iTrader: (2)

What he said

Who the hell honed that block? You shouldn't have a different ring gap for each cylinder, they should be fairly even across the motor and not .030 loose

13173

If either one of you read my post you would notice that I said "Some rings were simply placed into the bore and not filed" I did not mess with some of the rings as the end gap was already pretty dang big.......

Also, me and a friend that is also a member of this board and who has showcased his build checked each thing that needed to be checked/measured not long ago. The bores were honed and the machine shop who did it, did a pretty dang good job. There was some slight variation on the dial bore gauge, but nothing out of the ordinary.

bgdriver

You'll be fine. Ring gaps on my Vitara SOHC DD are quite a bit bigger than that..

wantboost

iTrader: (2)

Whether they were filed or not, the gap shouldn't be that big

So the machine shop apparently did a **** job of honing

SpokaneSpeed

Regardless of the discussion on end gap size - ALL cylinders should be running the same gaps across the board

Muckman

iTrader: (2)

What is the EXACT bore? And what multiplier are you using for the gap (bore x .00??)?
Im confused why some are filed and some are not? Are you filing them with an angle grinder? You have a spread of 5 thousanths on some of them.

Those ring gaps are all way too big already (unfiled or not). Buy 4 new ring packs.

13173

Keep calm and troll harder......."There was some slight variation on the dial bore gauge, but nothing out of the ordinary" or that one would typically see when checking out the engine before putting it together.

I totally understand that the ring gaps need to be the same across the board. I can make them all equal as best I can with what I was supplied with. I stopped filing when I realized that some of the rings were bigger than my end gap calculations when they were brand new out of the package.

Also, I have heard of end gaps bigger than this. Not necessarily for a Honda engine, but I do not build several engines a year nor do I really build anything else other than Honda engines. But obviously some people do.

13173

Bore size is 3.4455" and the multiplier I was going by is bore x .0065/.007" for the top ring and .007/.008" for the second ring.

I stopped filling rings when I saw that the second ring was already at .030" and had never touched my filer. From that point I just stuck the rings in and measured. These are the measurements I got.

Seems to me whoever made the rings for CP had a bad day at work. My cylinder bores are not that out of whack. Cylinder #3 are for sure two of the rings that I filed and they are smaller than the rest. The 2nd rings on the rest of the cylinders were never touched other than to be measured.

I read a lot on another forum, more than I post anyways. On there I have read where guys have gotten bad packs of rings and I have also seen where guys run really big ring gaps, however, that was not on a Honda engine. It seems that may be what happened to me. With this build that does not surprise me.....

wantboost

iTrader: (2)

Try moving rings around to different cylinders. If the measurement changes the hone is fucked. If they stay the same you have a bad ring pack and need a new one

As stated the ring gaps need to be uniform. And .03 is rather large. You'll have issues with blowby, poor cylinder sealing, etc.

And don't try and troll the master :p
I troll hard lol

13173

Yeah, I did that. End gap measurements stayed the same..........then I snapped an oil ring in half right as I was about to install it in the cylinder. That flippin blows, but was going to have to get new rings anyways. Going to see what CP says about this tomorrow. Might just give them a call instead of waiting for an email reply.

wantboost

iTrader: (2)

I would definitely call, they get slammed with e-mails

Also I think your multiplier is off (don't quote me though lol) I always go by info off endyns site www.theoldone.com

Muckman

iTrader: (2)

Ok if the top ring UNFILED is bigger than the ones you have alrady filed then thats a problem. If you move it other cylinders and the gap stays the same then the bores are consistent obviously.

Get new ring packs and start over.
And pick a single multiplier. bore x .0065 for top and .0070 for second is good for a big power turbo engine. Sometimes the second ring is large out of the box which is OK just make them consistent.

tepid1

You'll see some people order larger rings so that you can get the gaps you want, not what they give you by default.

Also, gaps and PTW are dependant on fuel type and power. If you're using ethanol then I'd run gaps and PTW on the tight side, but gas is a different story. If you are using gas then you want to open up your PTW quite a bit. I'd shoot for at least .005 PTW depending on power.

Almost all of these comments are null and void until we know your fuel and power goals.

13173

Fuel will be gasoline and power on pump gas I am shooting for 550whp or so. On race gas i have enough fuel system for something around 750whp based on what I have seen other cars make by the same tuner. The engine is not going to be a full race engine, so street miles are more important than making maximum power.

I just talked with CP, the guy I talked too also said that the gaps were too big for what I was going to be doing with the engine, which is what most people would say. He offered me another set of rings from them with the same part #, but I am a little leery of that and do not want to waste money on them and end up with the same results. I talked with some other guys and someone suggested using Hastings Rings. They were V8 guys though.

tepid1

Get 88mm rings and file them down to what you want.

That's pretty high for pump gas and really close to the margin for even 93oct, but to each their own.

The numbers you came up with .022-.024 and .024-.026 are what I would do for a street driven motor. The tighter side of the spec will give you better performance. Looser than desired, you need to make sure your PCV system is up to par. Personally I'd go with .022 on top and .026 on the second ring. .015-.018 for the oil guide rings.

13173

You got a part # for any specific 88mm rings or what do you suggest using? Anything specific?

I really have no clue what the engine will make on pump 93 octane, just going from what I have seen the 550whp is just what I was shooting for. If it makes over 500whp, I am cool with that. It is a rod/piston K24 using a PTE 6765 and .82ar. Has ID1000's, bosch 044 and walbro 255. I wished E85 was an option for me, but it isn't. Closest ethanol pump is around 70 miles away, if it is still there.

tepid1

I'm not familiar with CP's part numbers. If they offered you new rings just have them send you the next .5mm size bigger. Can't hurt to ask.

wantboost

iTrader: (2)

Yea 550 on 93 is brave. That's basically the ragged edge or a bit over for only straight 93 octane. I would highly recommend a water/meth injection system with a high methanol ratio (70/30) to help dop IATs, bump fuel octane a bit and help eliminate any signs of detonation

Your tune has to be dear nuts accurate for those power goals on 93, detonation is a serious risk ane at that level the slightest bit will kill your motor in no short order. Also if you ever get a bad tank of gas you can kiss your bottom end goodbye.

I don't know what you're doing for a tuning solution but I hope you employ numerous failsafes to protect your motor and I'm hoping you're incorporating a knock sensor as well so you can have various failsafe measures like wideband o2 monitoring that either lowers boost, pulls timing/fuel etc and have a knock count threshold so the ecu can pull timing and other things I mentioned. You'll have to keep an eagle eye on various things like lambda, fuel pressure, knock, IATs, etc

If e85 is plentiful in your area I would ask that you seriously consider that as a safer alternative to 93. You'll have a much greater knock threshold and can make 550 plus with a much larger margin of safety and error should an issue present itself

blackeg

see i hate this crap. it seems from my personal experience that there is always 1 ring that comes way too big of a gap to use right out of the box and i wind up having to order another set.

.004 might be a tad tight but tune it well and i think you will be ok. i used .0045 for my cp's at about 500hp no problems.

your gaps can be up in the mid to upper .020 range for the 2nd ring, but id keep the top ring around .023-.025 max

13173

Wantboost, I am not sure if you have really read any of my posts in this thread, or just randomly post to make your post count bigger than it already is, but I have already stated that e85 is not an option for me. I am also not installing a meth kit on this setup. Reason I said 550whp on pump 93 is because two friends of mine with B series engines and and smaller turbos have both made between 475 - 501whp on pump 93. And on top of that the one that made 475whp was with B16 cams and a PTE 6262 with an E cover. One was just taken on a good 10 hour road trip. Neither of them have a meth kit on it and both were tuned by a good reputable tuner. I have faith in my tuner as he has made over 800whp on a few stock bottom end K20's, not on pump gas of course, and they were obviously on the absolute ragged edge, but he did it just to prove a point.

I have been posting on this message board since 2001, I have also been messing with Hondas since around 1997. If I am in here checking and posting about the gap of piston rings on a K series engine, wouldn't you think I would already know what I would need to do to monitor knock and air fuels? My oringinal post about the ring gaps I found could have been confusing and I could have probably worded it differently, but I know a little about tuning and what is needed to keep the engine happy.

Yeah, now your post sounds like others that I have read. I have read that it is almost normal for some to get rings that are oversized right off the bat.

2k.civic.si

how about no ring gap...total seal rings

13173

Not sure how I feel about that. Do not really know anything about it.

13173

Hey tepid, just talked with CP and ordered a set of rings that share the same part # as my pistons except for one number. I asked him about some for an 88mm bore and he suggested that I not do that for fear that the rings may not be completely round in the bore once I got them down to the correct size that I would need to run. While looking he did run across the rings I just ordered that are slightly bigger than the original part # I had problems with.

So we shall see what comes of this.