<br /><br />Anyway, I'll brief it up a bit:<br /><br />I pulled the motor from my boat last week, after a long, dogged period of diagnosis (to which the usual suspects on this forum contributed great chunks of knowledge and expertise - thanks Don S, Bondo, et al.!) revealed that I was experiencing bearing failure (mains or rods or both - I just know there was a LOT of metal in the oilpan and in the lifters and in the....well, you get the idea!) I have taken the motor to a machine shop near where we are set up in Oregon; Virgil (www.hansonautomachine.com) is a master engine builder and will be performing a complete reman and upgrade for me, with some "special treatment" items that I have specified that should result in a boost of between 15 and 30 percent of normally-aspirated output which, for my 3.0L means a bump to nearly 150 hp. I don't want to go much higher, as I want to preserve the reliability and maintainability that makes these little 4-bangers such favorites with us boatheads. There are more 3.0s powering marine applications than any other engine - more, I've been told, than all other engines combined. Whether or not that is true, there are more than enough that need one or more of the modifications that I've been working on to address some of the performance and output issues that plague smaller-displacement powerplants, such as high-altitude operation.<br /><br />Before I had to divert my attention to this complete engine reman, I was working on a forced-induction solution that will maintain sea-level manifold pressure, allowing generation of rated horsepower with high-altitude operation. I got the idea from the good experience I had with the turbo-normalization of the engine in my airplane. It is able to maintain sea-level MP up to about 20,000 feet, and I can't even fly over ~12,000 feet without supplemental oxygen!<br /><br />I've designed and custom-fabricated a belt-driven supercharger based on the Garrett turbocharger unit from a 7.3L Powerstroke (International Navistar) turbodiesel engine. It's a blow-thru system, and I'm still fiddling with the design of the carburetor airbox. The number-one design goal I set was reliability, driven by the twin attributes of simplicity and user-friendliness. I do not intend for this system to be used to produce obscene amounts of excess horsepower but, rather, to allow the engine to breathe normally at varying altitudes. That's how turbo-normalization differs from straight turbocharging or any other forced-induction scenario: you're just trying to help the engine generate its usual output by helping it get its usual input charge.<br /><br />I'm testing the blower system on a test engine my buddy and I set up for this purpose - I have no desire to test it on the motor in my Stingray, even after I get it back in and buttoned-up, as we all know about the contortionist positions we have to attain in order to work on anything installed in a boat!<br /><br />Anyway, I will, naturally, share the love with my fellow 3.0 engine owners and, perhaps, even make available a forced-induction package solution to guys like us, who hit the water wherever it may be found, even at over a mile high. 
<br /><br />I am thinking about a TBI conversion, too, but I have a greater desire to explore the forced-induction potential. Fuel injection and a good performance cam can make a difference but, at the altitudes we're dealing with, you're still behind the ball with either because you're dealing with lower ambient atmospheric pressure - less air to mix with the fuel - resulting in a reduction in horsepower regardless of the cam or how well-tuned the fuel injection system is. Besides, a TBI conversion, running upwards of $1500, is little more than a somewhat more precise method of metering fuel than a carburetor; I am waiting to see how well the Mercruiser 3.0 MPI measures up, performance-wise, and how it affects the rated output of their base engine. Word is it's up only 10 hp from the current 3.0's 135 hp to 145. For my dollar, I'll spend less to get more, and I mean more air, more power, more options and more money left in my pocket.<br /><br />BTW, Tailgunner - we're hanging out in the Albany/Corvallis area just down I-5 from you! Actually, I don't really understand how essentially (no, ACTUALLY) the same engine can produce LESS power with a higher compression ratio - the calculation is NOT rocket science, and it's pretty simple to see that a drop of 0.1 on the ratio should not equate to a gain of 5 hp, but a nominally perceptible DROP in output. The configuration of the pistons has a great deal to do with it, but THESE ARE, ASSUMABLY, THE EXACT SAME MOTORS!<br /><br />I'm leaning toward Sealed Power piston hardware, as it is readily available for my application and offers the precision and specificity I am looking for(I am, at heart, a scientist; my chief career has been in medical science and technology); I could put more money into it by using stuff like Keith Black or Federal Mogul/SpeedPro hypereutetic pistons (Mercruiser uses hypereutetic pistons in some of their high-output engines), a clearance crank and Scat rods and such, but I'm not looking to race this motor, only boost the output by ~30%. I'm going to try to achieve the perfect balance of power, reliability and servicability without spending more than a similar boat with a bigger engine would cost - every man's vision quest when it comes to his machines. Besides, flat pistons yield better flame travel than domed, so I'll likely stick with flat-tops.<br /><br />I'm not sure about the cam yet. Obviously, I want something hotter than stock, but remember - I'm looking to balance higher performance with this motor's renowned "little engine that could" economy and bullet-proof servicability (properly maintained, of course). Talk of seamless bearings, HP lifters and alloy rods is being tossed around, and I'll pick and choose the best mix for my targeted goal.<br /><br />The head will definitely be treated to upgraded valves and seats and we'll do some porting work to smooth out the flow. Roller rockers to replace the stamped originals are a must, and the rest of the moving hardware (springs/bearing/etc.) will be considered with their contribution to the whole.<br /><br />Sorry I can't be more specific, but I haven't finished ironing out my shopping list, and I keep batting away the nagging urge to splurge. I want to build up a motor that is stronger, more powerful and as economical to run as a stock 3.0, yet is accessible to any guy on this forum who wants MORE POWER (nod to Tim Allen, there) without having to spend the kids' tuition money to achieve it. In other words, I'm trying to end up with a motor that puts out ~150-160 hp, normally aspirated, that costs less than $3500 to build from the 3.0L GM L4 you already have in your boat. This niches it neatly between the stock 3.0L's 115-135 hp and the 190 hp output of the stock carb'd 4.3L V6.<br /><br />Now, about the forced-induction version, that's another story..... <br /><br />Did you have to use a gasket spacer with the domed pistons? You don't apparently have any clearance issues - do yo know what your clearance is with the hypereutes?<br /><br />I seem to remember some fellows on this forum indicating that you need an additional 10-15 hp to achieve each additional mph at WOT. Adhering to that range of power, you apparently have upped the ante by 40-60 horses! My own opinion is that the number is much lower, like 5-7 hp/mph, so you may only have a 20-30 hp improvement, but, HEY! - it's all good! <br /><br />We're planning to be back on the Western Slope sometime in August, if we don't head down to Texas or New Mexico first. I'm a technical consultant for Medicare, so I've been traveling around the country for a couple of years; this year the whole family came along, but we're about ready to be back home in Colorado. My wife is entertaining an assignment somewhere in the south Denver area and I'm looking at a contract just north of C'Springs, so we may yet end up just up the road from you. If you want to exchange e'mails, we can keep in touch and I can look you up when we come out to the Front Range!
