[brian eiland]

..thought this might be of interest to those that have gas engines on board

"In addition to employing lightweight design, hybrid drives, and optimized injection systems, automotive industry development engineers are designing smaller internal combustion engines in order to achieve their ambitious targets of significant reductions in vehicle fuel consumption, and thus of carbon dioxide (CO2) emissions, in the next few years. Early market analysis by Continental led to the conclusion that almost all European and Asian engine manufacturers were focusing on developing small turbocharged gasoline engines, and that there were excellent opportunities for growth in this segment in the next few years"

...more HERE

[Blair]

Strange way of scritping this advert blurb perhaps - bit stale perhaps to talk about car manufacturers only now focussing on turbocharging. Surely a relatively high proportion of European and Asian car manufacturers offer gasoline powered cars amongst their model range with turbocharging already? I reckon turbocharging of gas engines in certain production models has been around for a good 20 years or so but I guess the trend is to extend its advantages more broadly than the Subaru Sti type of rocket ships and other performance related models to achieve the power, extra torque and efficiency offered. I know there are after-market turbochargers for most gas engines (plus the magic chips of course!) these days as well but I suspect, like anything on a boat, adding 50% to the output means looking at transmissions and shafts and props too!

Maybe engineers can offer wiser comment but it does seem inevitable that small turbocharged high torque gas engines will replace the big capacity but old technology vehicle-sourced V8s common in fizz boats as well, just like cars. Mind you, apart from scary prices by comparison, hard for any marinised gas engine to compete with modern supercharged/turbocharged diesels that offer similar performance results - with better inherent safety and less to go wrong - maybe.

(useless info: I do recall hearing some time ago that those turbocharged Seatec(?) diesels then used by the top teams in offshore power boating (in their outrageous 1400HP race form) had a rebuild life span of about 6 hours! At around 600 HP with the boost wound way back when spec'd for more 'normal' marine use rebuild spans increased to several thousand hours.)

[AMG]

My Corvair Corsa was delivered with turbo already in 1966. In cars they are a good option and almost all manufacturers have used them today.

In boats however, they are a bit scary. A friend had two high performance V8 alu engines fitted with turbos and besides all other problems they finally caught fire. I doubt the insurance companies would like to see a glowing turbo in the engine room of a boat running on petrol...

[Blair]

Yes, I've notice that sprint boats mount their twin turbos and dry exhausts very high indeed - with no engine covers of course! I guess that engineering solutions will reduce risk but......

[Grecko]

Colin Campbell in his classic book "The Sports Car, It's Design and Performace" (when I first read it in the mid 1960's) said "As a means of finding the weakest point in an engine, supercharging has no equal."

That is as true today as it was then. Turbocharging or supercharging crams more working fluid (air) into an engine. The net effect is that you have more and heat released, and thus higher temperatures in the combustion chamber and exhaust system. This makes it harder on things like exhaust valves and you have to remove more heat from the cylinder head. Exhaust valves run sufficiently hot that a 25 degree F increase in temperature can cut the life in half (stress rupture life at temperatures above 1800 F). The net result is that trying to get too much power from any particular engine will trash it in short order.

Cars are being pushed by fuel mileage regs and that favors a small engine. The customer wants more power, so they hang a turbo on it to get the best of both worlds. That works for the duty cycle you see in cars, but not for boats.

Boats can run at high power for long periods, and if you try to get too much out of it you are not going to see much life. Better to get power from more displacement than trying to boost it with a turbo.