Piston Ring Gap [Merged 5-7] gapping rings pistons end filing

[99gst_racer]

quick question--> me and a friend just put my shortblock together and i gaped the top to 31 thousands, and the bottom to about 27 thousands.. i was told by the machine shop that its probally not going to hurt it. . "is this true?

block is 30 over. 6 bolt
weisco coated pistions
eagle rods
knife edge crank
no ballance shaft.
everything balanced

You need to replace those rings. .031 is a huge gap for a top ring, and your 2nd should be looser, not tighter than the top. The loosest gap I would probably recommend would be what sb7775 stated above. Anymore gap than that and you will have low compression and alot of blow by.

Is this motor going to see very high boost?

 

[BrokenTsi]

holy geeze. Thats def no good. Id go .019 on top, and i usually see .021-.023 on the bottom. I dont think id go any looser on anything street driven.

 

[china]

well the thing is that , when i did the ring gap, the paper that comes with the pistons, that has the math formula for the ring gap .004 times 1 inch of bore.. .or whatever it is.. .. . anywayz, what im trying to say is that , i was told that more boost will help seat the rings... i plan on seeing like 30-35 psi.. so this way at that boost pressure, the rings will def. seat... and it says on the paper. use a higher number for RACE APPlication. .. the only thing im worried about is noise. kinda like piston slap.. .. well. i duno.. this is my first 4g63 build. I have no prior experience with these engines------------ a little history about the car...--------- i have not even seen the car run. i bought the car (2g) and 1 day later crank walk. . so i pulled the the motor out 1 year ago, and im finally getting it back 2gether. ... looking to make 500hp ... no juice.... ... . and one other question that someone can answer.. where do i get the oil feed for the turbo. it was a year ago i took this thing apart, and i kinda dont remember where it all goes.. .. 1g bottom, 2gen head. .. a little help. thanks. ---

 

[china]

one more thing.. since its that big of a gap, how long do u guys think it will last being driven every day... maybe track twice a month. thanks

 

[sb7775]

First of all 500 whp is a very high number to shoot for, you are going to need all the supporting mods and some very good tuning. And back to the ring the gap is still to big weather it a street or race car. Its going to make a lot of noise especially on cold start ups. I would buy a new set of ring and set them up like i mentioned before. I'll have to double check my numbers but the bore(use the number on the side of the piston box) 3.8 X .004 should be around .016 not the .031 your coming up with. With the number you are talking about we would almost have a 6in bore. To much time and money to tear it down later just because you didn't want to spend a few extra bux's now.

Thanks Steve

 

[99gst_racer]

China - The more boost you run, the bigger gap you should have. As cylinder pressure insreases, the gap will start to close. You do not want the ring ends to touch and exert pressure on each other. That is how you get broken rings and ring lands. Even at 35 psi, I feel you gapped them too much. Especially if the car will be street driven. I would recommend dropping in a new set and gapping them at .019 on the top and .024 on the 2nd.

but the bore(use the number on the side of the piston box) 3.8 X .004

The factory bore on the 4G63 is 85mm (3.346 inches) not 3.8".

 

[diamondstargsx]

well i got my wiseco std bore 8:31 pistons today.i have a vr-4 motor with very low miles and the bore is good checked but i need to know what ring end gap is recomended.mine are top ring is in.015 and mm.381 and second ring is in.021 mm.533.

FACTORY SPECS BELOW

ring in bore is top first ring 0.25 to 00.45 and mm.0098 and .0177.second ring end gap is .35 to .050 and mm.0079 to .0276.

 

[BISHILVR]

This is a common subject, here is a recent thread for you:http://www.dsmtuners.com/forums/showthread.php?t=189875&highlight=ring+gap

 

[TSIfreek]

I would get the bores lightly honed to remove the glaze off the cylinder walls so the new rings will fully seat. Unless it has 5000 miles on it I would get it honed or at least ball honed by a professional with the correct stones.
Also with your gaps .018 on top and .020 on the bottom work very well for moderate boost levels. 25+psi daily requires slightly larger gaps than above because of the added heat placed on the pistons and rings.

 

[blue1]

Diamondstargsx i think you better your Factory ring gap specs! you will have people gapping their rings with a power saw

 

[BrokenTsi]

You have to hone those cylinders to get rid of the glaze or those rings will never seat. Keep an eye on wall clearance tho, id recommend minimum .003 for wiseco's personally if this car is gonna see any type of decent boost/power. Id also recommend going .018 on top, and leaving the bottom .021. Bigger than that isnt necessary, but i wouldnt suggest smaller unless this motor isnt going to see much boost.

 

[diamondstargsx]

street will be 21 psi on my scm 50 like befor and 26 psi on race gas.

 

[BISHILVR]

Wiseco has a 800 number, honestly I would give them a call and tell them your plans and ask them for clearances, we have to do that once and a while at work. Its free, you have nothing to loose.

 

[90turbotsi]

I was installing new OEM Mitsubishi rings on a set of 2G pistons and I noticed that the OEM service manual has a different diagram then the instructions included with the OEM rings. I have included 2 pics below of each of the diagrams. Let me know what you think of this and which I should go with. Ive always seen the Books orientation but figured Id ask before its too late

Book specs are first and the instructions that came with the rings are 2nd:

 

[gsxtacy]

Both of those look to be useable. I noticed that the second one shows the 1st and 2nd on the same side of the piston.
I have always been told the 1st/2nd should oppose each other and that all the piston rings are set the same.

I took a Sharpie (medium point) and put A, B, C, D around each cylinder on the block in accordance with the first drawing that you supplied.

I made sure that each pistons' rings' corresponded with A, B, C, D.

This is a good topic.

I highly recommend that everyone who rebuilds their own engine, buy, borrow or steal a set of piston ring spreaders. Spiraling the rings on is dangerous to the ring and the pistons, and more importantly dangerous to your fresh engine.

Follow the instructions on the rings in accordance with a Service Manual, there is a UP and DOWN on most compression rings.

Most of all good luck.

gsxtacy

 

[power=dsm]

I highly recommend that everyone who rebuilds their own engine, buy, borrow or steal a set of piston ring spreaders. Spiraling the rings on is dangerous to the ring and the pistons, and more importantly dangerous to your fresh engine.


Most of all good luck.

gsxtacy

Whats wrong with installing the rings by hand? When i rebuilt a 6 bolt i installed the rings by hand. Motor has 160 compression? Is it just a security measure.

 

[huafist]

Whats wrong with installing the rings by hand? When i rebuilt a 6 bolt i installed the rings by hand. Motor has 160 compression? Is it just a security measure.

What's wrong with installing the rings by hand is exactly what gsxtacy mentioned - there's a chance of spiraling the rings, which will kill them and possibly the pistons.

 

[90turbotsi]

I agree...and used all the right tools with it including ring spreaders. Id much rather do it right, plus this was not the 1st and im sure wont be the last motor I will have on my bench to assemble so its good to have the tools. Tools are the key (as you im sure agree).

I have them all set at this point like the factory book says mainly due to being taught many years ago by a mitsu tech that the rings needed to be 180 degrees off from eachother well 1-2 especially. Just figured Id see what everyone here thought about it since both my printouts OEM say differing things. In regards to the up and down, yes the book and papers said any markings or numbers on the rings(1R & 2R for these OEMs) go up.

I got my head all together today and the last few parts and plastigauge for the bearings...Hope to get the bottem end together tomorrow When I get a little more progress ill post pics of my build.

 

[FastGS-T]

Alright, I ordered .020 over Ross 8.5:1 pistons for my 6bolt build. I did some researching and pretty much see that .019 is good for the top ring gap but what should the second one be?

I plan on running my evo3 at 20psi

Searches showed a ton of different ring gaps you guys recommended so I couldn't decide on anything. Should I just use whatever Ross recommends?

 

[-Stroked-]

Always use whatever the manufactor recommends. Those pistons are made specifically to handle boost and the rings are set to be a certain gap. Just put them in the cylinder to double check there specifications.

 

[FastGS-T]

Got the .020 over Ross pistons for my 6bolt. Do the rings come already gapped?

 

[TSIfreek]

No they dont come gaped. Use the search on this board.

 

[FastGS-T]

Well don't think I was asking a stupid question, I just wanted to lead up to this one. The instructions said to add .004 to the gap on the rings for every 30hp per cylinder that is planned to be added. But when I searched, I found people saying "Use OEM spec" and "Use manufactuerer Spec" I don't know what to gap them too. I have a built 6bolt and will be running a 50 trim with fp2 cams. Probably in the 350-400 range. Is the stock ring gap sufficient for my setup?

 

[power=dsm]

ya i checked with ross and they said to use the stock gap. You should call them and ask for their info.

 

[steve-o_95_GST]

When I called Ross about my ring gaps, I told them what my goals were with the motor and all (450hp and ~26psi) and spoke to 2 people there. They told me to do a .005 wall clearance but I cant remember off the top of my head what the gaps were, but I will post them up when I get home.

-Steve