Piston Swap

mkIIIdrifter

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#1
Ok, I have 2 supras. I have a 86.5 7m-ge and a 88 7m-gte, well i kind of melted of destroyed pistons 2 and 5. Well I hardly drive my 86.5, I had plans to make it a show car but yea... I was wondering if it would be possible to take the pistons out of my 86.5 and put them in my 88. Is that possible or would I have to buy new pistons? If I have to buy new pistons, where would be the best place to buy some?
 

Fletch124

2jz swapped!
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#2
Theres a good change that you will have bore your cylinders in order to clean them up. So new pistons will be manditory.
 

Boost_happy

breakin it sideways!
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#3
I would just get new pistons, just over a $100 for stock nippon pistons with rings off ebay, plus they look pretty decent and you can get them .020 over. Good replacement if you jsut want to get it running again and have good reliability under light mod cnditions... Anyone else have luck with these pistons?
 
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#4
Ok, I have 2 supras. I have a 86.5 7m-ge and a 88 7m-gte, well i kind of melted of destroyed pistons 2 and 5. Well I hardly drive my 86.5, I had plans to make it a show car but yea... I was wondering if it would be possible to take the pistons out of my 86.5 and put them in my 88. Is that possible or would I have to buy new pistons? If I have to buy new pistons, where would be the best place to buy some?
I know your on a tight budget so the best thing would be to swap the hole bottom end from the GE when wiring up the Knock sensors on the new block,

Take both the sensor wires and wire em to one but get a MHG to bump down the compression a little bit,(GE's have higher COMP) make sure everything things properly prepped.

You may want to use the head on the GE (There Identical other then the intake cam) as well if you got it hot enough to melt a couple of pistons I'm sure the head is warped
 

Motofool

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#6
if you dont run alot of boost and dont push the limits of the stock fuel system much, you can run GE pistons and benefit from the higher compression for offboost and low boost condidtions it will make the car much more responsive and a tad more powerful, but you have a greater chance for detonation to occur because your have raised the compression or pressure in the cylinders before you add boost,

if your going to try n fix your turbo block get new pistons and bore it out make it right you dont want to do this twice it will cost more then doing it right the first time.
 

Dan_Gyoba

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#7
As stated... The NA pistons = hoigher compression.

Mounting the 2 knock sensors to the GE block is going to be tricky, but can be done. There are 3 bosses on the block for the sensors. The GE used the middle one, the GTE uses botht he front and rear one.

Also, the GTE block has the oil squirters to help cool the pistons. The GTE block would be a better choice, and easier in the long run, most likely more reliable.

First off, though, look at WHY you mented a piston. If you did that with the 8.4:1 compression, it'll only happen sooner on 9.2:1 compression if you don't identify and resolve the original problem.
 

86_sports_1jz

slow 700hp build...
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#8
just rebuild the block and do it right the first time. don't waste your money
 

D-Dayve

Still in pieces...
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#9
You CAN change pistons like that, and it will run. I ran into a problem on an engine and until I figured it out, I was going to keep blowing pistons, so I didn't want to fork out big cash until the problem was fixed. So, I grabbed a spare motor and every time I blew a piston, I'd just pop off the head and slap in another piston and re-use the head gasket (this whole idea is not a very good and is a very crappy band-aid fix that should NEVER be used to fix an engine).

The problem is that when you hone your block, you put a cross-hatch on it similar to a file. As the piston travels up and down the bore with new rings and a new hone, the hone files the rings into the shape of the cylinder (no cylinder, freshly machined or old is properly round). This makes the rings conform to the slightly improper shape of the freshly bored cylinder so they seal nicely. This crosshatch that acts as a file is usually only good for about 500 or so miles. After that, if you have an oil burner, you're stuck with it.

The point I'm trying to make is that NO used rings that you have will perfectly match your cylinder's bore since it will be worn. That coupled with the fact that you won't have a cross hatch to seal the rings properly means that it will ALWAYS be an oil burner with low compression on that cylinder.

Unfortunately, the cylinder wall is naturally hardened by running hot and having oil splashed on it. This is called the glaze. You can't just hone a cylinder because this hardened layer has to be bored out before you can re-hone the cylinder.

So, I hope that helps you make your decision on what to do. You CAN just slap a used piston in there (I've done it knowing the consequences), but you run the very real risk of having an oil burner and a crappy engine.