hackish
06-04-2010, 03:53 PM
One of my customers has an Elise turbo. It came factory calibrated with a unichip. I've been working on a reflash for said vehicle for a long time and complaining that it would not be reliable with the piggyback computer. 11.5:1 compression ratio and boost can be reliable but it gives you about 0 margin for poor tuning.
So I got the call this spring that the engine was sick and something was needed. The car arrived and we set to work removing the block. The toyota 2ZZ-GE is actually designed by Yamaha and from what I've read shares some of the features of their sport bike engines.
Tearing the engine down I immediately saw that the block is very well re-enforced with a 2 piece crank girdle. Like many performance engines it has oil squirters.
http://www.psituned.com/projects/3/images/lotus1.jpg
http://www.psituned.com/projects/3/images/lotus2.jpg
The rods were one of the most impressive parts. Forged and as beefy as any crower I-Beam rod.
http://www.psituned.com/projects/3/images/lotus3.jpg
The failure on this engine was caused by detonation and 3 of 4 pistons had failed ring lands. Although the pistons are very beefy as seen above they are a high silicon content which make them very thermally stable but brittle. Tight tolerances, good emissions but not detonation tolerant.
http://www.psituned.com/projects/3/images/lotus4.jpg
The little bits of aluminum from the broken pistons unfortunately made their way through the oiling system and the rod bearings show some signs of this.
http://www.psituned.com/projects/3/images/lotus5.jpg
Fortunately the bores were OK so we're planning to do a set of mahle forged pistons, all new ACL bearings and an upgraded oil pump (another weak spot on this engine).
I would like to do a little work on the cylinder head but looking at it I suspect it already flows pretty well from the factory. It also won't fit on my flow bench so it would be a bit of a PITA to build a new fixture just for curiosity.
-Michael
So I got the call this spring that the engine was sick and something was needed. The car arrived and we set to work removing the block. The toyota 2ZZ-GE is actually designed by Yamaha and from what I've read shares some of the features of their sport bike engines.
Tearing the engine down I immediately saw that the block is very well re-enforced with a 2 piece crank girdle. Like many performance engines it has oil squirters.
http://www.psituned.com/projects/3/images/lotus1.jpg
http://www.psituned.com/projects/3/images/lotus2.jpg
The rods were one of the most impressive parts. Forged and as beefy as any crower I-Beam rod.
http://www.psituned.com/projects/3/images/lotus3.jpg
The failure on this engine was caused by detonation and 3 of 4 pistons had failed ring lands. Although the pistons are very beefy as seen above they are a high silicon content which make them very thermally stable but brittle. Tight tolerances, good emissions but not detonation tolerant.
http://www.psituned.com/projects/3/images/lotus4.jpg
The little bits of aluminum from the broken pistons unfortunately made their way through the oiling system and the rod bearings show some signs of this.
http://www.psituned.com/projects/3/images/lotus5.jpg
Fortunately the bores were OK so we're planning to do a set of mahle forged pistons, all new ACL bearings and an upgraded oil pump (another weak spot on this engine).
I would like to do a little work on the cylinder head but looking at it I suspect it already flows pretty well from the factory. It also won't fit on my flow bench so it would be a bit of a PITA to build a new fixture just for curiosity.
-Michael