Cause my machine shop messed something up with my bore I had to let buildt some custom pistons from JE.

84.51mm Pistons on B16.

Now my ring gap is 0.023" on Topring and 0.033" on the Second ring without any filing.
Usually I buildt my engines with 0.019"Top and 0.023"Second.

I asked JE about bigger rings but the only rings they could offer were for a 85.00mm bore. That fears be to be not round in the bore.

Other rings are not!! available.

What are your oppinions on that gap written above? Still accapable? What could this big gap cause?

 

If you ask me, ring gap is over-rated, especially on turbo cars. My opinion is that you will be just fine. Remember, that top ring gap is about what I would set as a hot street/strip car ( approx .007" per 1" of bore / 20-30 psi and approx. 600 - 800 whp on gas) and the second ring is mainly oil control, so no worries there, in fact most endurance engine builders set the 2nd ring larger like that to control heat.

 

If I take your 0.007"gap per inch of bore than I would be fine. Ok that sounds good.
As I first said I also usually set my second ring gap a little larger than the top ring.

You said that most builders make it to control heat.
Can you or somebody explain the technical background for that?

 

you could look at getting the next sized rings up and gap them down.

I am really suppriused you would allow a machine shop to get away with screwing up your bore and not either replacing the block or going to 85mm. Either wy it's your project, I jsut htink your letting a machine shop walk aoo over you. custom ordering pistons to fit the bore is wrong in my books. they should have stepped up to the place and made things right. I think you have a lto of thinking to do. now your stick with off sized pistons, rings that cannot be made to fit easly, and tons of extra $ spend for some else's goof.

anyway, good luck.

FYI ringgap is NOT over ratted. there's ar eason there's limits, it's to help you keep compression into specs. too much gap and it allows too much blow by to occure, too little and when the ring gets hot and expands, it will hit bind and could damage the cyclidner walls.

good luck man, your in a VERY tuff situtation.

 

IF THEY ARE DIFFERANT PER HOLE. PLACE THE LARGEST GAP IN TEH 1ST SLEEVE. IT STAYS THE COOLEST.

 

Custom pistons seemed to be a good idea because before I let JE build the custom pistons I asked if there rings are big enough to fit into the bore.

The problem is that the guy we build the engine for didn´t accept a 85.00 bore because it would give him room for a later buildtup.

Now JE suggests me to take theire 85mm rings and file it down to the gap I desire.
But I fear that the rings could not be enough round????
Hope you understand what i mean - I can´t find better words for that

Thanks

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by meanEG &raquo;</TD></TR><TR><TD CLASS="quote">IF THEY ARE DIFFERANT PER HOLE. PLACE THE LARGEST GAP IN TEH 1ST SLEEVE. IT STAYS THE COOLEST.</TD></TR></TABLE>

Not always. Number 4 gets to use the transmission as a big fat heatsink, and in a number of cases has run the coolest on cars I've tuned. A lot of that depends on how cyl 1 is breathing.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by oscarmayer &raquo;</TD></TR><TR><TD CLASS="quote">

FYI ringgap is NOT over ratted. there's ar eason there's limits, it's to help you keep compression into specs. too much gap and it allows too much blow by to occure, too little and when the ring gets hot and expands, it will hit bind and could damage the cyclidner walls.

good luck man, your in a VERY tuff situtation.</TD></TR></TABLE>

I agree, but I was stating that most people are way too focused on trying to get the ring gap as close as possible. 9 out of 10 times there is a problem with ring end gap, it's because the builder was too ambitious and tried to get the rings as close to butting as possible, and 9 out of 10 times they do just that, they butt. I am a fan of a little looser end gap, only because I have built so many motors now to think otherwise. I will retract my statement, and correct it by saying that having too loose end gap is not always a bad thing. Hell, just as an example, I ran .035 - .040 end gap in Ed Bergenholtz's engine, and that thing sealed up like a charm, never had blowby and makes well over 1400 HP!!!

 

What the ring is made out of means as much as gap, IMO. A lot of the guys in this forum are running moly when you should be running a steel ring with DLC or titanium nitriding, and a napier bottom ring. You blow out a tiny chunk of moly coating in a big power engine and you start losing ring seal fast.

 

My personal opinion on ring gap is that I like to run a tighter second ring and a loose top. First, your top ring is seeing more heat from the piston crown, and from combustion itself. In addition you want a top ring gap to allow cylinder pressure to get behind the ring and create your seal.

The second ring sees less heat, therefore will expand less. The second ring is also going to be your secondary backup to sealing the cylinder and controlling oil consumption. For that reason I like them tight yet safe from butting each other.

Running a real loose top ring, with an even looser secondary ring wouldn't float with me all that well.

Like stated above though, materials count. Your top ring may be a typical steel ring, while your secondary ring is made out of some other material. Expansion rates should be considered in those cases.

I'd personally look to resolve the problem instead of just going with it. Sure, it may work fine on an engine that will run the track 7-10 times, but longevity is going to suffer on a street engine.

 

Do you go with a finer or coarser hone with that sort of gap arraingement?

And, yeah, the OP needs to get his ring gap correct or he'll be unhappy.

 

Here's what I got out of the box from JE.

New Rings Gap
&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt; Top Bore Gap / Bottom Bore Gap
Cyl # 1 = Top Ring - 0.021 / 0.020
Bottom Ring - 0.020 / 0.019

Cyl # 2 = Top Ring- 0.025 / 0.024
Bottom Ring - 0.024 / 0.023

Cyl # 3 = Top Ring - 0.026 / 0.025
Bottom Ring - 0.025 / 0.024

Cyl # 4 = Top Ring - 0.025 / 0.024
Bottom Ring - 0.024 / 0.023


Old Rings Gap
&gt;&gt;&gt;&gt;&gt;&gt;&gt;&gt; Top Bore Gap / Bottom Bore Gap
Cyl # 1 = Top Ring - 0.030++ / 0.030+
Bottom Ring - 0.03+ / 0.030