Using .060" pistons in 4g63

[joat09]

I'm looking for some guidance. I have a 91' 6-bolt that I have torn completely down. I measured the bore of all the cylinders, and in cylinder 3 the cylinder wall was already .035" out from stock. It was originally a SBR block that was bored .020" over.

What I need some help with is if it is a decent idea at all to go with .060" larger than stock pistons. I am not even sure if this is possible. The machine shop I took my block to said they would have to bore the block out and could not limit the boring to .005". I'm not sure If I should buy a crate 4g63 block or buy a built short block. I would really like to keep the block that I have. I'm trying to go the least expensive route without skipping on the important parts.

If anyone has any knowledge of anyone trying the 4g64 pistons in a 4g63 and it being reliable let me know. Any other information or help would be appreciated. Thanks a lot.

 

[whe3ls]

your going to have the block sonic tested if you want to go .060 over.

 

[GSXSixteenG]

Anything over .040 is not recommend. That's why you probably can't find any 4g63 pistons in that size. If you want to keep your block you will have to sleeve it.

 

[pneumo]

Wiseco makes .060" oversize pistons. Part# K559M865
I used a set in one of my builds. It was nice having a little extra displacement. I had it for 2 years around 400hp. I scrapped it when compression started dropping. Thin walls wore unevenly at that power level.

 

[deth2u]

I'm running .040" over on a 4g64. The walls are paper thin, but it's holding. Car has been running and JSB up and down since '05. However, I wouldn't do it again--I think it's too great of a comprimise

Considering there's more meat on the 63 block, I'd say it wouldn't be a problem.

 

[Absit]

There's no reason you can't go .060 over when the 4G64 works fine. You can't use 4G64 pistons though.

 

[joat09]

There's no reason you can't go .060 over when the 4G64 works fine. You can't use 4G64 pistons though.

Do you mean 4g63? There is a reason, and that's because I plan on having around 450hp and .060" would be cutting it pretty close for the water jackets not to crack.

 

[Absit]

No, I typed what I meant. It's commonly said here that the 4G64 is identical except in deck height and bore, shouldn't the water jackets be in the same place?

 

[deth2u]

No, I typed what I meant. It's commonly said here that the 4G64 is identical except in deck height and bore, shouldn't the water jackets be in the same place?

They are. The oil drains are the only difference. Still a mystery why they casted it like that.

I do recommend the 64 if you want to go big displacement. It's cheaper as well; just snatch an engine from a Galant or Spyder GS. They're readily available and inexpensive. It has no problem handling the revs, assuming you do a quality build.

 

[joat09]

No, I typed what I meant. It's commonly said here that the 4G64 is identical except in deck height and bore, shouldn't the water jackets be in the same place?

That is a good point, although I'm not sure if they are that identical. Also, you don't too far away from me. Do you have a silver gsx?

 

[donniekak]

No, I typed what I meant. It's commonly said here that the 4G64 is identical except in deck height and bore, shouldn't the water jackets be in the same place?

Just because the water jacket ports are at the same location at the deck of the block, doesn't mean they are the same distance from the bore center in the block.

 

[Absit]

No, I have a red 95 TSI AWD and a paprika red pearl 98 TSI AWD.

It would be kinda silly to engineer the ports to be the same but not the jacket location.. I could be wrong but I was under the impression it was the same cast.

 

[JacksonAuto]

There is some bad info in this thread. You can go to .060" although it is good practice to sonic test the cylinder walls to be sure that there are no thin spots. We've never come across a 6 bolt that was too thin although there is always the possibility of an anomaly due to core shift or other casting variances.

On a side note, I would bet that it was never decked. This means that the bores will not be perpendicular to the crank. I would recommend decking the block before boring it again to properly locate the cylinders.

 

[VTEC_THIS]

Our previous engine (2.3L 4G63) had .067 custom pistons made by Wiseco. The difference between standard bore and .060 over is one and a half millimeters or just under six hundredths of an inch. I don't think many people realize how slight the difference is between the different piston and bore sizes.

Standard bore is 85mm
.020" over is 85.5mm
.040" over is 86 mm
.060" over is 86.5mm

Just take a look at Wiseco's site:
http://www.wiseco.com/Catalogs/SportCompact/MiniMitsu.pdf

 

[williillii]

I would not worry about it at all. Like they said. The 4g64 86.5mm bore blocks are just "4g63" blocks that are machined with slight differences.

 

[joat09]

No, I have a red 95 TSI AWD and a paprika red pearl 98 TSI AWD.

It would be kinda silly to engineer the ports to be the same but not the jacket location.. I could be wrong but I was under the impression it was the same cast.

Do you ever run them at Cordova?

There is some bad info in this thread. You can go to .060" although it is good practice to sonic test the cylinder walls to be sure that there are no thin spots. We've never come across a 6 bolt that was too thin although there is always the possibility of an anomaly due to core shift or other casting variances.

On a side note, I would bet that it was never decked. This means that the bores will not be perpendicular to the crank. I would recommend decking the block before boring it again to properly locate the cylinders.

Our previous engine (2.3L 4G63) had .067 custom pistons made by Wiseco. The difference between standard bore and .060 over is one and a half millimeters or just under six hundredths of an inch. I don't think many people realize how slight the difference is between the different piston and bore sizes.

Standard bore is 85mm
.020" over is 85.5mm
.040" over is 86 mm
.060" over is 86.5mm

Just take a look at Wiseco's site:
http://www.wiseco.com/Catalogs/SportCompact/MiniMitsu.pdf

Thank you very much for the great information.

 

[Absit]

Do you ever run them at Cordova?

I have not, the 95 is for sale and the 98 isn't track worthy yet.

 

[keltalon]

Anything over .040 is not recommend. That's why you probably can't find any 4g63 pistons in that size. If you want to keep your block you will have to sleeve it.

Not recommended by whom? If you mean mitsubishi then we all have violated every rule out there from mitsubishi standpoint in modifying any part of our car whether it be the engine for performance, ecu for tuning, tire size for looks, body, ect. 60 over is hardly anything for a 4g63 engine block. I have used several 60 over pistons over the years and yet to see any adverse effect on performance or reliability

There is some bad info in this thread..

I agree with jackson! Its bad infomation with no references that leads down the road to destruction

 

[Slowboy]

There is some bad info in this thread. You can go to .060" although it is good practice to sonic test the cylinder walls to be sure that there are no thin spots. We've never come across a 6 bolt that was too thin although there is always the possibility of an anomaly due to core shift or other casting variances.

On a side note, I would bet that it was never decked. This means that the bores will not be perpendicular to the crank. I would recommend decking the block before boring it again to properly locate the cylinders.

Never decked?

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To the OP - if you email me or PM me with the original purchaser information or the PN stamped on the block - I will see what info I can provide if you need it!

Mike Huml

 

[SBR Joe]

OP, we have built .080 2.3 stroker motors for the hell of it, because we had the block and got some pistons to fit it....and they are still operating flawlessly today. I NEVER would reccomend that, but the buyers didnt care for how cheap we were selling them, just using it as some back up info to let you know that .060 is totally fine.

On a side note, do you know how many miles were on the engine you have now? What was the SBR stamp number on the block? Id like to look up the original specs from the build sheet to give you all the info on when it was built and clearances, etc.

 

[evileclipse909]

I've got a similar problem that kind of relates to this thread. I recently had a block cleaned and machined however, Im starting to think there was a mis-communication between the machine shop and I. I asked them to clean it up and bore it 20 over, however, they said there was no need to bore it and that only one of the cylinders needed sleeved. When I picked the block up they hadn't invoiced me for boring it. So I orderd standard pistons. Well now that I'm trying to assymbal the motor none of the clearances are coming out. so I remeasured the block and I'm getting 85.24mm, 3.356". And the bore seems way too large for my standard pistons. Does this mean that they did bore it and just didn't tell?

 

[SBR Joe]

I've got a similar problem that kind of relates to this thread. I recently had a block cleaned and machined however, Im starting to think there was a mis-communication between the machine shop and I. I asked them to clean it up and bore it 20 over, however, they said there was no need to bore it and that only one of the cylinders needed sleeved. When I picked the block up they hadn't invoiced me for boring it. So I orderd standard pistons. Well now that I'm trying to assymbal the motor none of the clearances are coming out. so I remeasured the block and I'm getting 85.24mm, 3.356". And the bore seems way too large for my standard pistons. Does this mean that they did bore it and just didn't tell?

did they have your pistons when they did this to check piston to wall clearance for the hone?

 

[evileclipse909]

no they didnt. I measured the pistons and the width of the widest part of the skirt is 84.94mm, 3.344. So I'm definently sure I orders the wrong pistons since that would make the clearance .3mm or .012". and acording to wiseco's specs. the piston to wall clearance should be .0025.

 

[SBR Joe]

no they didnt. I measured the pistons and the width of the widest part of the skirt is 84.94mm, 3.344. So I'm definently sure I orders the wrong pistons since that would make the clearance .3mm or .012". and acording to wiseco's specs. the piston to wall clearance should be .0025.

Usually if you order STD bore pistons, theyre a bit fatter than OEM spec to accommodate for boring....sounds like wiseco just made them on the skimpy side. If you want, i can try to find some specs for STD bore Manleys, Mahles, CP etc that would work so you can maybe hawk those wisecos off or return them, and get ones that will work, to avoid you having to spend more money on getting the block punched out .020 over.

 

[evileclipse909]

Well thats the problem. I think they did bore the block. So I'll either need to get .020 over pistons or another block that is still standard bore.