5m-ge future engine mods?

[Mk2guy]

My pistons were made by Toyota Racing Development they are 85mm wide and give a 10.5 to 1 compression ratio. Toyota made these pistons to compete, using the 5mge, but that was eons ago. I heard reliability would tank if I installed tham...? I was just wondering how bad and if anyone new anyone else that did that. (my hp would be upgraded to about 240hp)

On mechrider89,s car, I would just replace the head gasket because it doesn't sound like he over heated the engine. It just sounds like the head gasket went. I depends on valve stem seals, last rebuild, maintanace, basically engine health. Only he would know that.

The one thing I know toyota did was make the torque specs to were you torqued the head to a certain ft lbs and then turned it so many degrees, rather than using the ft lb mark. (such as: 43lbs and then 3/4 turn) You have to watch over torquing the heads though, because I had a guy that over torqued his head bolts and he stretched the threads. (that's bad)

You might want to buy some new head bolts too, but I am pretty confident you just need a new head gasket. I hope you get back up and running soon, these cars are so fun!

[mechrider89]

thanx for the support guys, the only thing I'm leery on is the resetting the timing, everything else I'm totally fine with. I was going to do a compression test today but with 110 km/h winds thanx I think I'll pass. I really wish I had a leak down tester but being broke puts a kink in that plan.........a speeding ticket didn't help either.
Good thing is I have all the gaskets I need but the bad thing is my exhaust manifolds cracked and the bolts are so rusted I'll probably break them off.......god I cant wait till I can afford that pacesetter manifold.


Aluminum reacts with steel, you see it all the time on semi trailer rims. Steel eats the aluminum and causes aluminum to become more brittle which can lead to cracks etc...

[Mk2guy]

Ya, I heard that aluminum react with steel. something about electrons not matching and causing galvanic corrosion, which is rust I think.

Let us know how it goes though. I can talk you through the timing bit. That is easy. I would set everything at 0, on the compression stroke first, before you start the tear down. It is hard, but it's not a nightmare. I had to replace the pulley on mine. eveything was bad on mine. I spent $1500 on parts this year alone. $700 on parts the year before. Ya, your way ahead of me. Don't worry.

[mechrider89]

Originally Posted by Mk2guy

Ya, I heard that aluminum react with steel. something about electrons not matching and causing galvanic corrosion, which is rust I think.

Let us know how it goes though. I can talk you through the timing bit. That is easy. I would set everything at 0, on the compression stroke first, before you start the tear down. It is hard, but it's not a nightmare. I had to replace the pulley on mine. eveything was bad on mine. I spent $1500 on parts this year alone. $700 on parts the year before. Ya, your way ahead of me. Don't worry.

Lol well you can afford parts, I'm just trying to keep it fixed so I can do a dd swap. I'd like to push the talon out of my carport so I could work in a sheltered area, but my whole engine bays stripped paint and all and I don't want it to rust!

[CanadianBak'inSupra]

LOL don't just REPLACE the head gasket, without proper inspection...
for all we know there could be hair line fractures in the head, or it could be warped without repair...
follow the TSRM and you will be good.:http://www.cygnusx1.net/Supra/Librar....aspx?S=EM&P=1

as far as head bolts go strait edge them and inspect your threads. clean the threads in your block to insure proper torque

hate to bring it back but compression test will tell all. 14psi max difference between cylinders.

as for your pistons.
83mm is stock??
1982 5mges have 8.8:1
1984 and up get 9.2:1
i ran a quick search on ebay celicasupra.com and a few other sites and came up with nothing on trd pistons, i would say you have some rare shit, considering stock 5mge pistons are discontinued.
if your planning on using them i would go for a block and head shave and metal 7mgte head gasket.
if toyota did infact make your pistons, there quality and i would not doubt there reliability, but from what i understand stock hg with 9.2:1 pistons was designed for around 180psi, your gona be pushin over 200psi with those pistons, and a aftermarket headgasket would be the solution.

[CanadianBak'inSupra]

Originally Posted by Mk2guy

Ya, I heard that aluminum react with steel. something about electrons not matching and causing galvanic corrosion, which is rust I think.

i believe they heat a cool at different rates as well

[mechrider89]

ooh ya no worries I was planning on going and getting it hot tanked, and get the surface check, and decked if necessary. Looking at valve guides and springs to because there's no way my valve seals aren't fucked, and the stock valve springs will more then likely fail there spring rate test.

And one way you can check to see if low compression's do to a hg failure or piston rings is to do a leak down test and or a compression test with a cap full of oil dumped into each cylinder. If the compression goes up with the oil its your rings if not the rings are good then.

For aluminum I believe there's 3 or for 4 strength stages, I know that semi rims are stage 1.

[mechrider89]

wow! thanx for the link bak'in its perfect!

[CanadianBak'inSupra]

check the part about cleaning and priming your lash adjusters.
when you drop your oil if there is evidence of lots of coolant you may want to inspect your bearings if that is the case.

[Mk2guy]

http://www.celicasupra.com/forums/sh...ston-Kit/page2

Here is the only place I have seen some one with pistons like mine, but I haven't heard anyone who actually has installed them, so it makes me nervous thinking about installing them. With that high of compression I am not sure if I could use pump gas either. I know headers allow you to run a bit higher compression, the aluminum head helps because aluminum cools quicker, but really I am just guessing. If I went that far I would have to have the block sonic tested to make sure that the cylinder bores can handle it and cryogenically freeze the block to make it stronger. (See the cost is already up there) Then I would have to have the heads flow benched after I ported and polished them, and then get a math guy to help me figure out if the stock cam would would need to be replaced, or if it is ok to use. Custom cams are cheap either. (not to mention getting the crank rebalanced) It would be different if my supra was a tidy one, but it isn't.

Toyota used these piston when they first started grand prix or Le Mans or something like that. They are primitive, Toyota technology at it's Genesis. That can't be a good thing. I don't think they are a good idea, so I am looking for someone who has tried this, to spare me the expense. ( Let me know if you heard of anyone doing this, other wise I will likely get curious and throw money at this project, like an idiot, just to find out.

Also, if you wanted to check if your rings are bad you can do a wet/dry comparison. Do your compression test then put oil, a few drops, in the chamber. It you get more compression with the oil in the chamber, like a lot more, then your rings are probably bad. You might be able to change the rings with the engine in the car. (I would have but my crank was bad)