I'm planning a type 4 turbo build for a 912.
I'm looking for three things: (1) reliability, (2) decent power (160-200 HP), and (3) affordability.
I'm a physicist as my day job, and in the past, I've worked in German car shop, and have built a number of T1, T4 and Porsche flat 6. This combination basically means three things:
- I'm poor
- I know physics, so I can talk about things like thermodynamics, fluid dynamics, heat transfer, heat capacity, all that fun stuff.
- I'm not bad with a wrench and TIG, and I can easily fabricate a turbo manifold.
I'd like to go turbo because under non-boost, the engine is less stressed than a comparable high-compression NA engine, and under boost, the engine's cooling system has to dissipate less heat than a NA engine producing the same HP. Plus, with a turbo, very fancy headwork is not nearly as important as an NA engine.
I'd also want the engine to look reasonably period-correct, I'd like to build a 912e turbo as Porsche would have done it in 1976.
So, here's my list of components that I'm considering:
- start with a builder 1.7 from a 914, but when I install it, I'll use the 912e engine tins.
- I'll mount the turbo down low, in the 930 location, air cleaner in the engine bay, and use the 911 engine mount holes for the turbo air inlet/outlet.
- Heads: AA Pistons ported 1.8 heads, with plugs at the 2.0 location, 44X36 valve size, $ 1,755.90. Seems like a good choice because of the extra material around the exhaust port, and the small-ish valve sizes.
- Cylinders / Pistons: AA Pistons biral 98 mm cylinders with forged JE pistons: $850. Nickies would be nice, but WAY out of my price range. I've worked some very rough calculations, with a 200 HP engine, I'm not sure the Nickies are required in terms of heat transfer.
- Crank: JE Pistons 78mm forged, chrome moly crank, ~$600
- full dynamic balancing by a reputable shop.
- oil system, undecided, might go dry-sump with a 911 oil tank and CB performance pump??? ($50 - $1000)
- piston oil squirters -- definitely case installed style.
- turbo: used Mitsubishi probably, I prefer the internal waste-gate style, electric scavenge pump.
- intercooler: Subaru WRX.
- injection system: Megasquirt full-sequential, wideband O2, boost control, with coil-pack spark control (engine management electronics is something I know extremely well, I've modified D-jetronic fuel maps in high school, and I work a LOT with control systems).
- rods: forged H-beam
Any experience with the AA pistons biral cylinders? Are these the spun-cast or sleave press-fit style. Any experience with the AA pistons forged chrome-moly cranks?
I've looked at the QSC nikasil cylinders, but can't seem to find much info on who's used them, what pistons/rings to use with them. The nikasil coating process is not that hard of an industrial process to do. Just not sure why I can't seem to find much info on who's actually used these in practice.
Any advice on who to use for a machine shop, to install the oil squirters, balancing, etc... I'm in Indiana, so local would be better, but I'm perfectly fine mailing the parts somewhere else.
Note, I do have access to the university machine shop, so I can easily check all of the specs on every part, and can do some machining myself.