4g61t.org

as the subject states... what is the max safe bore size for the 61t block.... i have read that people here have 63t pistons. 61t stock bore is 82mm. what is the 63t bore? 85, 86?

oh yeah, i have read that the combustion chamber bore size of the 61t head is the same as the 63t head... is this true at all... or am i dreaming up some BS?

thanx. looking to build a nice powerful 61t....

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89 turbocan, 63t, GT30-13 (laaaag monster), tubular manifold by me, maf-Trans, phil-tuned ecu, bla bla bla.... you get the drift...

well its the same block as the 4g64 and it has a stock 88mm bore and mitsu even sells pistons that are 1 mm over so I think safe is 89mm

What beserko said + make sure you read this thread about attaining a decent static CR:

http://www.4g61t.com/forum/viewtopic.php?t=5102

excellent info xlr8! Do you by chance have the name of the company that made those custom pistons for you? Maybe you have the dimensions?

thanx again!
phil

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89 turbocan, 63t, GT30-13 (laaaag monster), tubular manifold by me, maf-Trans, phil-tuned ecu, bla bla bla.... you get the drift...

Call Wiseco they'll build you anything you want...

Hello 9 year old post.

Well, I have some answers to the question of "max safe bore in 61T"

I have bored a 61t to 84mm, and had the cylinders sonic tested to make sure there is enough material left in the cylinder walls. At this bore, there was a minimum thickness (cylinder 1) of 0.160", which is plenty of meat. 85mm bore would be possible, and this would be a max bore for a street engine. If you were to go all out race only, i believe my machinist says minimum cylinder wall thickness would be 0.080".

88mm? race only.

As a side note, cylinder 1 was the thinnest, possibly due to a shift in casting.

There's your answer, mrgreengenes.

phil (mrgreengenes)

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89 turbocan, 63t, GT30-13 (laaaag monster), tubular manifold by me, maf-Trans, phil-tuned ecu, bla bla bla.... you get the drift...

Seems how the engines are all cast as a 2.4L deck with 1.6L bores and then machined down from there, you should be able to accomplish the same things you could with either a 4G63 or 4G64. FWIW Golden Eagle Mfg.'s sleeves they sell for a 84mm honda B series engines are 7.55mm/.297". And those have been proven to take as much power as anyone has ever been able to make with them.

I am 99% certain on the original size of the casting. I will have to try and source a broken 2.0L or 2.4L to verify the thickness again, but I am sure that is how things came from the original castings. I could be wrong and they had multiple size casting molds however.

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1985 Mitsubishi Cordia
Build in progress

Is there somewhere that this is a published fact? I have my 1.6L hyundai block out for sonic check as I type. I would love to go to 85mm or even 89mm, just to say that I did it... I think I read somewhere that if I use a 85mm flat-top 10.0:1 piston with the short stroke, I get 9.0:1. that would be fun. Does anyone know if I will have to deck the 2.0L pistons to make deck height 0.000"? Would a turbo piston have enough material before the ring lands to accomplish this? (I am N/A and have little desire to bolt on the boost.) any help would be appreciated, I'm not a big fan of surprises...

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DD: 98 Park Avenue
Project: 92 (E)Lantra J1 G4CR 1.6L N/A
[Bucket of 4G63 parts from ECMLink to turbo cams, 450cc injectors, GM 3" MAF Sensor, on and on and on...] to pour into it. Keeping the 1.6L though.

Not that i have found. But after tearing down and rebuilding nearly 100 4g6x engines, I just don't see how it could have been any other way. I do know that each size up in bore does reduce the cylinder wall thickness compared to the next smallest engine. I have had one of every size apart with major damage and have seen all the wall thicknesses. And it is very clear when you see the engine decks how thin the bore separation is on the 2.4L block.

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1985 Mitsubishi Cordia
Build in progress

Sounds Promising.. When I see the results of the sonic check, I will post them here. Thanks for the info. Now to find pistons that will work without breaking the bank.

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DD: 98 Park Avenue
Project: 92 (E)Lantra J1 G4CR 1.6L N/A
[Bucket of 4G63 parts from ECMLink to turbo cams, 450cc injectors, GM 3" MAF Sensor, on and on and on...] to pour into it. Keeping the 1.6L though.

Good deal, I would also be very interested in the final results and please post about the piston you choose.

Hyundai may have bought the plans for the motors from Mitsubishi, but they didnt get their castings... My G4CR (4G61) is only .50mm oversize and there is one point in one bore that has a wall thickness of .088" I seem to have misplaced the printout, but when I find it, I will put up the whole thing for all to see Does anyone know if there are wet sleeves available to accomplish putting 85mm pistons into this block? Does Darton make custom wet sleeves?

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DD: 98 Park Avenue
Project: 92 (E)Lantra J1 G4CR 1.6L N/A
[Bucket of 4G63 parts from ECMLink to turbo cams, 450cc injectors, GM 3" MAF Sensor, on and on and on...] to pour into it. Keeping the 1.6L though.

Which flat top piston did you have in mind, I believe that turbo pistons have about a .200 crown thickness.

best bet is to call darton or any other sleeving machine shop

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89 turbocan, 63t, GT30-13 (laaaag monster), tubular manifold by me, maf-Trans, phil-tuned ecu, bla bla bla.... you get the drift...