> And for more on that, GPASC says that for maximum engine life, the max > > should be 8 to 1 on the 2180 and 8.5 to 1 on the 1835. >
I did a bit of stuff with turbos about 20 years ago on car engines, and a lot of research. A lot of the problems faced in fitting turbos to 1950/60 designed cars are exactly the same probs that you face today with bolting a turbo on to a beetle engine. The first question is blow or suck:- Blowing. The simplest way to bolt on a turbo is have it blow into the carb, the problem is the carb then has to be pressure tight, and if you have a suitable carb, you have to then go thru lots of pain to get it jetted correctly - not so difficult on a car that generally lives it's whole life at one altitude, not so easy on a plane. The carb runs hot which makes vapour lock a serious issue, as much as for this reason as for charge density reasons an intercooler is vital. Sucking. So you decide to suck - ie put the carb in front of the turbo, from the carb point of view that is easy, getting the correct carb is simple, a 1600 engine will need a carb suitable for a 2300 engine job. Now the turbo becomes the problem, when you close the throttle the turbo oil seals see negative manifold pressure, and all the oil gets sucked into the inlet manifold. This leads to badly gummed up valves or total loss of oil. A further problem with sucking is the long inlet tract, this makes starting difficult and hand cranking pretty well impossible. Common Issues. Turbos get very hot, they glow red hot. obviously they need good ventilation. Pretty well all cars with turbos have electric fans that continue to cool the turbo after it stops spinning. Without cooling, the oil in the turbo gets turned into coal, and the oil seals also get completely destroyed. This is the main cause of turbo failure. Most turbo race engines have a BIG red light that comes on for low oil pressure!!! If a turbo seizes, you get a dramatically reduced flow of air thru the turbo - perhaps insufficient to maintain level flight. Just a few little things to think about... Pete
