Posts Tagged ‘big block’

Mouse Block that roars

What happens when a knowledgeable marine engine builder starts down the waterway towards a High Performance Go-fast small block “mouse” marine engine? 570 horsepower at 6,000 rpm from a mouse engine block that roars.

ilmor 570 engine marine image sport boat race, pleasure, go fast, offshore

Side profile of Ilmor 2014 small block 570 HP marine engine

Chevy (GM) makes lots of blocks just like they make lots of engines. They make a LS-series small-block V-8 that is the basis of an engine that makes 750 horsepower at 7,100 RPM. But, it is only intended for short-burst runs. Think 12 seconds at a time. Question, can one start with that small block and modify it for marine use where a run down the lake may take 25 minutes or longer?

Paul Ray decided that it could be done. He is president of Ilmor. Ilmor started in 1983. Seabuddy believes that the seed money for Ilmor was provided by Roger Penske.

Seabuddy attended a charity roast for Roger in Palm Springs, CA a long time ago. Unfortunately, the racers on the dais that night cared that Mr. Penske did not really want to be roasted, so they did not say a lot of dirt. And Roasts are about good-fun dirt. Only, Augie Pabst, who had raced against him in the late 1950s to middle 1960s, told the stories that we, in the audience, carne to hear. Augie is heir to the Pabst Blue Ribbon Beer Company, and basically stated that he was beyond any future blackmail pay-back from Roger, so he let it rip. Good fun and a great story about a rental car left in a swimming pool after one race. Seabuddy will say no more.

Back on topic, Ilmor built engines for Mercedes Benz, Chevrolet, Oldsmobile, Honda, Me Laren and Indy Cars, among others. Within CART races their engines won 64 out of78 races in five years. Ownership of Ilmor has changed over the years and Paul Ray got more ownership of the company each time from Penske, Chevrolet, and Mercedes Benz. Also, Ilmor Engineering has since expanded to facilities in NC, MI, and the UK.

Marine engines began with a racing presence with Skater for catamarans and Fountain for vee- bottoms in 2002. These were often with an Ilmor V-I 0 engine set that started with a Chrysler Viper block. By 2010, Paul Ray expanded his pleasure boat line-up with a 5.7 liter 320 horsepower at 5,000 RPM, a 6.0 382 HP at 5,200 RPM engine, and a 430 Hp at 5,400 RPM engine. All with Chevy blocks and all are catalyzed. These engines are used by Mastercraft and are considered tow boat water sports engines. To top off that line up, for 2012, Ilmor made a 454 cubic inch mouse motor small block (also catalyzed) which is good for 522 horsepower at 5,800 RPM. This is the most powerful CAT engine and it runs on 87 octane gas. This CAT converter engine runs 70% cleaner in emissions testing than a non-CAT would.

These 2010 engines were first used by boat builder Mastercraft in their water ski tow boats, wakeboard boats and family tubing usage. See their 2014 Prostar, for example. The last engine (522 HP) was developed for use in their over 25′ and their heavier family ski boats (see their X-55 model). They have sold at least 300 of these 522 engines now.

Ilmor engineering tow boat engine for Mastercraft

Ilmor 522 Hp small block marine engine for Mastercraft boats

Now, the Mouse block motor that roars! Hey, 570 horsepower at 6,000 RPMs is a roaring mouse.  They used the Chevy (GM) Racing LS-X block as a starting point. That block has a 4.185 bore and a 4.l25 stroke. That makes it a 454 cubic inch displacement in a small block V-S. Then Ilmor modified the block in house, primarily in taking steps to keep up good oil pressure while running very fast down the bay.

This is a cast iron engine part that uses a 6-bolt cylinder head attachment pattern. GM makes a drag racing 6-bolt head that matches up to this block that takes 2.25 inch intake and 1,625 exhaust valves. Again, Ilmor modifies this part, too. Let’s just say, a lot of longer wide- open throttle running durability improvements is tied to special oil circulation and engine temperature control. These are hand built engines with many parts custom-fabricated to Ilmor’s design specifications- including forged cranks, rods, and pistons. This last engine does not have CAT Converters.

Ilmor engineering small block chevy 570 Hp marine engine

Another view of the Ilmor most powerful, 570 Hp small block chevy


Ilmore engineering 570 small block chevy

Green finished 570 Hp small block chevy by Ilmor Marine Engieering

Mercury Marine 8.2 engine, First Boat / Engine Test

Push the throttle down from idle speed in a 7,500 lb. boat in South Florida and feel the surge. She gets going quickly. It’s the camshaft profile, the 502 cubic inch big block size, the Bravo III x, and the Mercury Racing XR prop set, all working together to provide the family boater with the newest engine from Mercury Mercruiser Marine.

Take the tach up to 2,500 – 3,000 rpm and let the boat settle down to a speed at that rpm. Now push that throttle down again and feel the biggest difference between the now out-of-production 496 Mercury big block and the newest Merc big block engine.

The surge that pushes you back in your seat at 3,000 rpm is the biggest seat-of-the-pants experience that most boaters will feel the first time they get to try a 8.2 Mercruiser inboard outboard.

Yes, the 8.2 is quiet, smooth, and even pretty to look at. The Catalytic Converters (one for each cylinder bank in a V-8) in the exhaust make it quieter than a big block without them. Next, its so pretty to look at for a boater than we had to stop to just gaze at it in the engine compartment and how Mercury laid out everything on this boat engine. They make this one from scratch, unlike the now out-of-production GM Mercury Marine 496 engine.

See this Mercury Marine engine for yourself here…

or, here from 3/25 – 3/28 at the Marina Del Ray Cobalt booth…

ask for Patrick, in either case.

More about the boat and engine test on the next page.

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