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.060 Overbore

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95TalonOwner

15+ Year Contributor
1,313
27
Oct 18, 2005
Milwaukee, Wisconsin
Anyone ever gone 60 over? My block is already 40 over and it needs to be cleaned up to 60 since there is no 50 option for our motors. Otherwise I'm also trying to source another block soon.

Thanks.
 
Those walls will be mighty thin. If you do it keep us posted idk if has ever been talked about with our cars.
 
Yeah, you are starting to push the service limit on that.... I'm sure it would be ok if the car was in stock trim, but not sure how it would hold up under more power. Seems like the thin walls may become a problem.
 
Find a shop that can sonic check the block, this will tell you the thickmess of the cylinder walls. That should tell you if you are ok to go .060 over.

But the cost, about $100, you may just want to get another block.
 
Do the,4g64s come with thicker walls? standard bore on those are .080 larger than the,63. Mine, friend just bored is,.020 which would be 87mm bore.
 
Walls should be fine in terms of strength, I would be more worried about in terms of heat dissipation. If it was a track only car, I'd say go for it, but with a daily driver, and possible heating problems i dont know. Also You would need customer pistons, whether you go .050 or .060 over. Why not go .045 if you can get away with it?
 
The problem with those sizes is I cannot find rings to fit. I don't want my machinist to get into all of that if I just find another block to punch to .040 instead.
 
custom rings isnt that hard to find or get made. All depends on the money you want to spend.
 
Or if he has good forged .040 pistons, get another block and take it .040 and reuse the pistons
 
One of the pistons in question.... LOL

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Last edited by a moderator:
That ^^^^ is NOT a good resuable piston.

New block and .020 over for you.
 
I'm not questioning the pistons because I'm not retarded. I'm either boring the block .020 more and calling it a day or finding a bare one and having it punched out .040 again for my 2.2L.
 
I'm not questioning the pistons because I'm not retarded. I'm either boring the block .020 more and calling it a day or finding a bare one and having it punched out .040 again for my 2.2L.

I didn't think you was.,, was, just stating some carnage there LOL. Ill ask my brother what he thinks he is turbo car guy majoring in chryslers. Though imo I'd say, you could get away with it. You could do .045 .050 depending on how much bring is needed. You can contact nippon racing or maybe cp and maybr wesico and have them, make a custom piston. I'm sure if they will make, the piston they can do the rings as,well.
 
Do the,4g64s come with thicker walls? standard bore on those are .080 larger than the,63. Mine, friend just bored is,.020 which would be 87mm bore.

No, the 4g64 isn't made with any thicker walls. 4g64 stock bore size is 86.5mm which is only 1.5mm (.060 over) from 4g63 pistons (85mm stock). It's not recommended to bore the 4g64 much larger unless you have had the cylinder walls check very thoroughly. Plus, I only know of forged 4g64 pistons going to 87mm so any larger and you would likely need custom pistons.
 
Custom pistons.

So I did ask my brother about this and he said that he wouldn't go that far. He told me .040 would be as large as he, would go. He knows,more, about it than me as I said he majors in turbo_n/t chryslers and has been working on cars for close to ten years now. he, is very knowledgeable in the turbo side.

So even though I thought .060 might be doable I don't recommend it now. Amd have,to agree with svo. New block and .020.

No, the 4g64 isn't made with any thicker walls. 4g64 stock bore size is 86.5mm which is only 1.5mm (.060 over) from 4g63 pistons (85mm stock). It's not recommended to bore the 4g64 much larger unless you have had the cylinder walls check very thoroughly. Plus, I only know of forged 4g64 pistons going to 87mm so any larger and you would likely need custom pistons.

ok cool thats what I thought. Yeah I knew the bore, sizes I just didnt know the streetable bore limit. Thanks bro.
 
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