Hey guys I was reading about someone doing a destroked 7m using a 5m crankshaft and some crazy rare 85mm pistons to make a square 7m. It was a NA build and it didnt last too long but it got me wondering if it could be somewhat feasible to drop in a stock piston from another engine that is 85mm for a 7mgte build. After thinking I remembered the 4g63 engine has a 85mm stock bore. Just trying to see if anyone has tried to drop 4g63 pistons into a 7mgte (with some machine work of course) for an overbored 7m? It would give a 85mm bore and they came in two different compression ratio's 7.8:1 and 8.5:1 depending on the year which would probably be different in the 7m anyhow. Wrist pin is 22mm and I think the 7mgte wrist pin is a tad bigger so some machining there as well. Just thinking it may be a low cost option. I've got a total of 4 7m's and thought it might be fun to try and build a 85mmx85mm 7mgte. Let me know your thoughts.
4g63 pistons?
- Thread starter timtiminy
- Start date
possibly, but i do see some problems:
: finding 6 of them, as you would need 2 sets
: machineing cost making them fit.
also 85mm is a bit big for the 7m block. that 4mm of material between cyldeners missing, which could be what casued the previous build of this kind to fail.
: finding 6 of them, as you would need 2 sets
: machineing cost making them fit.
also 85mm is a bit big for the 7m block. that 4mm of material between cyldeners missing, which could be what casued the previous build of this kind to fail.
For the hassle just go with custom pistons from JE, CP, Wiseco, Arias, etc. HKS made a set of 85mm or 86mm pistons way back, but finding a set would be few and far between.
Its not recomened to go past 84mm.
Iirc it was aaron from driftmotion who was doing that build and the biggest problem was that the crank snout was too short for the 7m.
Iirc it was aaron from driftmotion who was doing that build and the biggest problem was that the crank snout was too short for the 7m.
They are as the section between the cylinder walls will be paper thin at that point. Prolly the reason why you will never find a set.
Getting a custom forged crank is going to be a couple g's. Not really worth it in the long run. Spend like 5k just in a rebuilt long block. Be better to just get a brand new long block and boost the crap out of it.
Getting a custom forged crank is going to be a couple g's. Not really worth it in the long run. Spend like 5k just in a rebuilt long block. Be better to just get a brand new long block and boost the crap out of it.
85mm is doable with a late block with minimal core shift but Sonic checking the cylinder walls is a must before trying to punch it out that large.
I wouldn't do it on a Forced induction engine though, small bore thicker walls and a touch more boost will result in a far better engine.
I wouldn't do it on a Forced induction engine though, small bore thicker walls and a touch more boost will result in a far better engine.
i am building a 85 x 85mm NA 7m with a 5m-e crank and custom pistons. i am going for 12.5-13:1 so havent bothered looking for another standard piston as i will need dome. it ends up at about 2.9lt
i reckon 85 is the max limit of the block, but should be ok.
the crank snout was a bit of a bitch, but i have fixed this, below is the full belt driven setup on the 5m-e crank:
goal is for 9000rpm and 300-350hp @ flywheel
i reckon 85 is the max limit of the block, but should be ok.
the crank snout was a bit of a bitch, but i have fixed this, below is the full belt driven setup on the 5m-e crank:
goal is for 9000rpm and 300-350hp @ flywheel
why is the 5m snout a problem? I've never seen a 5m crank in person (never worked on a 5m) so I'm a tad clueless with this
the 5m-e has a chain driven cam and smaller harmonic balancer so is a fair bit shorter in the snout:
which leaves bugger all hanging out the front, only a couple of mm engagement for the balancer:
the 5m-ge is belt driven so probably ok in the snout but runs a narrower #1 main bearing so no good. by using the 5m balancer i also save a fair bit of weight, with lots of other work i have dropped the rotating mass from about 55kg to 43kg
with the 280 deg cams its should be a real spinner!!
which leaves bugger all hanging out the front, only a couple of mm engagement for the balancer:
the 5m-ge is belt driven so probably ok in the snout but runs a narrower #1 main bearing so no good. by using the 5m balancer i also save a fair bit of weight, with lots of other work i have dropped the rotating mass from about 55kg to 43kg
with the 280 deg cams its should be a real spinner!!