HaxbySpeed

"Superchargers are for people who don't know how to build engines" - I can't remember who's quote that was but if you look past the obvious jab that was intended it's based on the fact that it's a lot easier to make power with a blower. It'd be hard not to make 600-700hp with almost any supercharger and a BBC with mediocre heads and exhaust manifolds to boot. To make 700hp NA takes some better components. That being said if you're building your own engine and you want 650-750hp it's a no brainer with todays technology and components. Lots of people like using the xx1 cams that are 15-20 years old and although they make good power there are much better lobe profiles available that are waay easier on your valvetrain, there is also much better spring technology available today as well as various coatings and treatments that really extend top end refreshes. A modern cam, good cylinder heads with a good quality spring package and a well executed valvetrain along with 540-557 cubes, you're lookin at an easy 700+hp package on 89 octane and a long long life. It takes a little more planning and a more careful selection of top end bits but you'll end up with a lighter, more efficient engine with less belts, pulleys, parasitic losses, etc. Once you get past 800hp the supercharger becomes a much cheaper option for making the power.

MILD THUNDER

iTrader: (3)

Good post dude. I remember talking with Bill Lawson from ateco on the phone a few months ago. He was discussing the 540CI packages he is using now. He made some good points when I was considering ditching my blown 454 based engines. He thought I would be really impressed with how a pair of modern N/A 540's would run in my boat.

He said that his 540 marine package has came a long way in the past 10-15 years. Mainly thru cam selection, cylinder head selection, and so on. The old 540's that maybe made 600hp 10+ years ago, are now making 730HP and just as if not more reliable than the old ones..

I had a 540CI marine engine years ago. Nice stuff for the time, dart blocks, merlin marine heads, crane 741 cam, dart single plane intake, dominator carb. On the dyno it made about 590HP, 610FT lbs. I can see where newer better designed heads and cam could have woke them up.

I decided to stick with the setup I have, mainly based on budget, and I do like the roots blower look/sound.

HALLETT FAN

A supercharged / turbocharged engine has a nice flat torque curve , good for all around boating ...

JasonSmith

Technology is so much better today than it was even 5 years ago. I don't think a supercharger is any more work than a big cubic inch engine. Both are going to require special attention on the valve train at regular intervals and both are going to use "x" amount of fuel.
I think the supercharger has an advantage because it is not always making atmosphere. Most folks don't run around with their hair on fire in the boost. Those that do change oil the hard way more than those that don't.

Raylar

+1 Could not agree with Haxbypeeds post more!
With good head, intakes, camshafts, exhausts and a good build its very easy to make these numbers at usually less cost than for a more expensive supercharger system.
As for fuel milage the marine superchargers that are in the market today, most use more fuel at cruise speeds and higher rpms than an equivalent N/A engine of same power. If you do huge amounts of running at idle where fuel milage may be important for you, DON'T BUILD OR BUY A MARINE HIGH PERFORMANCE ENGINE!
As for longevity and such the well built N/A engine will outlive most supercharged engines by a large factor.
As we see in the sport and hear about here on OSO the incorrectly or poorly built N/A and supercharged engines are disasters in equality!
Best thought here is don't buy or build any performance marine engine that is not done right and will not support reliability or longevity - PERIOD!
That being said, if you like the low rpm kick, noise of a supercharger and the bigger HP numbers from higher boosts, then there are excellent systems out in the market today - so enjoy!

Best Regards,
Ray @ Raylar

A.O. Razor

Just remember, that when saying x abount of hp takes x amount of fuel no matter what, not so. It needs a "minimum" of fuel, but sometimes some setups are less efficient and use more than needed. It depends on several factors, to sum it up it's about who utelizes the fuel the best. Modern high compression N/A motors and turbo motors that don't waste power driving a belt driven SC, has the advantage. Just look at the numbers for the Ilmor MV-725 vs. the 700SCI. 50 gal pr. hr vs 70 gal pr. hr. Numbers are more alike lower down, but the problem with running an SC motor with "mediocre" heads, to re-use the expression", is that when in the low boost part, flow is bad and efficiency is down. As Jason said, it takes just as much attention to detail to build a good forced induciton engine, as it does to build a good N/A motor. I know we should not talk about milage in this sport, but fuel consumpsion tells just as much about how well and efficient a motor runs and is a sign of a good combo.

Kurt Hamilton

Thanks guys. Eases my mind a bit. Have already spoken to Eddie Younge in pm's and I believe he is one of the most genuine people I've ever dealt with and has an excellent rep to boot. Unfortunately I live in australia so will most probably use a local builder (eddie has offered to consult with him.) I will definitely use the very best in parts for the build. I believe in doing things once and right.

Panther

They typically don't start sucking down the fuel until you get into boost. But, they do burn more fuel than a NA engine, that I can attest too!

Also, a blown engine makes much more torque than the same cubic inch NA engine that makes the same amount of power. The mid-range power of a blown engine is higher in a blown engine from what I've seen.

In a boat, I'd rather have the torque to keep the revs down than make the HP of a NA engine and have to spin high revs.

For instance, take a 750 hp 502" cubic inch engine. The NA engine will need to have high compression ratio with good heads and large camshaft, spinning 6500 rpms, maybe even more. The same engine, with a blower can make the same power @ 5600 rpms with stock heads and a mild camshaft.

I think it all depends what you want. This is all my opinion, I'm no expert.

mike tkach

iTrader: (3)

but you are right,most people who run supercharged boats are not worried about fuel consumption,i know im not,you have to pay to play,thats the bottom line.

Panther

What I found interesting going from my Scarab Panther to the Apache was this;

The Scarab had 502's, NA, roughly 550 hp a side. It burned 30 gph @ 50mph (3600-3700 rpms).

The Apache has 580's, blown, 830 hpa side. It burns 40 gph @ 60 mph (3600-3700 rpms).

So at the end of the day, it's not a huge difference in cost of fuel because the cruise is that much faster at the same RPM. I can back down to 3200 (50mph) and burn about the same fuel as the Scarab.

Now maintenance on the other hand, the two boats are worlds apart in cost to run year in and year out.