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305 c.i.d. HP topic
This is in response to a thread that was discussing the limits of
naturally aspirated HP in a 305 c.i.d. engine. Well, first, I must confess I don't know too much about recreational boating engines specifically. However, there is much in common between car and boat engines. As far as reliable operation is concerned, lets look a moment (bear with me) at the Infiniti G35 VQ 3.5 liter 6 cylinder engine. Normally aspirated, it puts out 300 HP (up from 260). And it has been rated one of the top engines in a car under 50K for about 10 years. Now I realize it isn't apples to apples. The air intake might be more restricted in the boat engine without a fair about of help--I don't know. But the point is today's engines are more advanced, without the bolt-on technology enhancements. Just to get a sense of what's possible by comparison, the Nissan Skyline GT-R 2.6 liter inline 6 cylinder (RB26DETT) with twin turbos has been modified over and over again to 600HP+ with just bolt-ons and a new engine management computer as a start. Some have modified them to greater than 1000HP. That's not naturally aspirated, but that's also a 2.6 - 2.8 liter engine at over 1000HP without NOS! Incredible. Look at the Suzuki Hayabusa. 1.3 liter inline 4 cylinder motorcycle engine running about 170 HP stock. Mods take it over 200 easy, still naturally aspirated. And turbo Busa's run upwards of 400HP+ without NOS--certainly pricier. Now, there are design limitations to some engines, but the naturally aspirated 305 is capable of more than 260 HP. Using that engine block with modern components and design tweaks, it would seem that much more can be achieved. If not, use a different engine. Unfortunately, I don't have specific 305 examples on the top of my mind, and I'm not sure what some might call reliable performance either. However, take this additional example from the 2007 SALEEN S281 3V Coupe Mustang, which is a high quality built engine by Saleen. Running it moderately most of the time and hot sometimes with proper maintenance, this thing wouldn't quit on you for a couple decades or so... ENGINE Type 4.6L, 3V, SOHC V-8 Bore and Stroke 3.55 x 3.54 in. Displacement 4.6 liters, 281 cu in. Accessory Pulleys Saleen Underdrive Pulleys Exhaust System Saleen Stainless, 2.5 in. Variable Exhaust Horsepower 335 bhp @ 5200 RPM Torque 345 lb-ft @ 4500 RPM Fuel Premium Unleaded 91 Octane Intake Saleen Design Hi-Flow Inlet Tube and Air Box Granted, Saleen's Hi-Flow Inlet Tube helps air intake, and a front engine design puts the intake in position to swallow a lot of air, but this is still the naturally aspirated version of this engine, which is smaller than the 305 by 24 cubic inches. And one thing I don't see limitations on in a boat engine is exhaust. It seems that should be an advantage from a design potential standpoint. Not sure what emissions regs there are, but I would be surprised if it is more than cars in the state of California. Haven't heard any push for hybrid boat engines for example. By the way, this upfit mustang costs around 44K retail, which includes ALL of Saleen's adders. The engine itself, without the highly touted Saleen Supercharger, isn't that particularly expensive, which means it isn't simply a case of throwing money at overengineering like a Porche or Ferrari or something. It is powerful, practical, naturally aspirated and reliable--which are all criteria of this topic. And I'm not saying boats need this engine. I'm saying the same concept can be applied to many engines. Of course, this is a high volume engine (in its original configuration from Ford) which helps the base price of each. A specialty engine would have to cost more to deliver the same result when looking at amortization differences (total cost & profit / num of builds). |
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