454 "Crate" HO to Marine

Ford built a 352 "FE" Big Block back in the 50,s and 60,s

Never saw or heard of a 350 "Big Block". Could you be more specific?

356 cu in Chevrolet "Small Blocks" have been used for years by Nascar. These Engines produce over 700 Hp and are operated at 8000 rpm+ for Hours on end, the time it takes to travel up to 600 miles. That sounds like high RPM relialibility to me.
Obviously they are built with components to withstand these Extreme conditions as well a Boat Engine could Be.

 

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marathon river racing jet boats in "B" class use 350ci chevs commonly..
450 to 750hp is common and they run at full hp and rpm during up to an 1 hour race including countless times when the engine bounces of the rev limiter when air born or pumping gravel at full hp. they hold together (mostly!) bit you are spending serious money.

we run crate chevs at load on about 4500 to 5200rpm with no issues..
the cheap crate motors with chinese copy parts etc will not last.

 

They are built with a 454 block but have sleeves to bore them down. The main bearings are a single cast unit that is also structural to prevent the block from twisting.

 

Interesting, How do they fit the intake and exhaust valves inside the cylinders when they're opening?

 

I'm not sure what you mean by fitting the valves. Also, they have needle bearings like an outboard. The oil pump is very high volume and runs with no pressure.

 

When the Valves open in a Big Block Head, I believe, they take More space than the Bore Dia of a Sm block, keeping in mind the valves protrude slightly into the Cylinder Bore when open. i.e. that's why there's valve reliefs cut into the pistons

 

Again, I have to call BS here. Gonzo, you don't have a clue about automotive racing and you need to stick to what you know - because you're throwing out a lot of really bad information. No, let me rephrase that - you're spitting out a lot of crap that has no basis in reality, and I'm tired of you misleading people who are just looking for honest info.

1) You do not de-bore a big block to meet displacement rules for a racing class. Doing that will cost you the race - the smaller bore interferes with airflow into the cylinder. Instead, you de-stroke it. That way, you retain the superior airflow of the larger bore, can run bigger valves as well, and thus can run higher rpm, making more hp than you would if you de-bored it.

2) Smallblocks can be had that hold together for hours at 1200 hp and 8,000 rpm. There's no need to pay the weight penalty for a big block if all you want is reliability. I can go down to my local GM dealer, in fact, and order a block that is rated BY GM for 850 horsepower. These are the exact same blocks used by NASCAR in 3 hour, 500 mile races. For that matter, I can buy the exact same LS7 block used by GM race teams to run and win the 24 hours of Daytona, the 24 hours of Le Mans; or I can buy the same Rocket blocks used by the offroad rallyers for races like the Baja 1000. You don't have to be a racer, or a member of the good ol' boy network, or have any special credentials. All you need is cash.

3) Mercruiser engines are simply automotive blocks marinized for corrosion resistance. They use the exact same blocks, they use the exact same cast cranks, they use the exact same cast pistons as the cars do. They don't even use 4 bolt main truck blocks. The only thing they do use from the truck engine is the cam - it's designed for low rpm torque, which, as it turns out, works great for boating applications.

4) The reason boat engines have lower horsepower ratings than automotive crate motors is because they actually produce less horsepower. Nothing else. Boat engines need lots of torque down low, and for that you need a truck cam. The sacrifice for lots of low end torque is less horsepower up top. It has nothing to do with cooling capacities, or different test parameters, or anything like that. It's just the sacrifice you make to get the best cam for your needs. The LT1 engine in my impala went through thousands of hours of testing on the dyno when GM developed it, including a 100 hour full throttle, full load test. That's 4 days at full throttle and maximum load without a rest. And that engine isn't even a race engine - it's in every 92-96 corvette, LT1 camaro, and impala ss on the road. The new 505 hp LS7 available in the current Z06 corvette went through a 300 hour full throttle dyno test.

5) The idea that marine engines are some sort of super duty mega tough behemoths is just not supported by the facts. GM's marine engines are based on their Vortec series of automotive engines. When I look at the page for GM's vortec 5700 marine engine, I don't see anything about special block alloys, or high performance bearings, or special .080" ring gaps for marine use. In fact, they don't even use forged cranks or pistons - they're cast, as are the main caps. The connecting rods are forged, but even they've been replaced on the automotive side with powdered metal - stronger, lighter, and better balanced than the old forged rods.

Judging by the obvious LACK of heavy-duty parts on these engines, it's easy to see that the performance demands made of marine engines just aren't that severe.

 

Stonebreaker: to start with, you keep on insulting me. Not just on this but other threads too. I don't know what you problem is but I am reporting this to Jeff. Your attitude has no place in this forum. Boat engines have more HP than car engines of the same displacement. Just look at the specs in a Chilton. As you said in the past, you are not a mechanic. Sonny Miller built 350 from 454 blocks to win many offshore races in the 80's. I never said they were car racing engines.

 

My attitude is fine. What I'm trying to prevent is some newbie who is on here looking for information from getting bad info from your posts. You may be a good mechanic, or you may not, I don't know; but I DO know that YOU don't know SQUAT about performance engines. Your above statement "Boat engines have more HP than car engines of the same displacement" merely proves my point - how the heck does the engine know it's in a boat and not a car? What pieces are in the boat engine that makes it better than a car engine? And which car engine are you comparing it to?

The reason I'm being so vehement is because if no one corrects you, then newbies assume what you said is right, and misinformation - bad misinformation - gets perpetuated. I'm not a mechanic, I'm a racer. What that means is I do what I do not for money, but for love of the sport. I don't seek to get paid, and I only post what I know to be true based on my own experience. My own experience tells me that, assuming you're an honest guy, you've bought the factory rep's sales pitch hook, line and sinker; but you don't really know how to judge on your own whether an engine is good or not. For example, your statement in the auto engine marinization thread about running a .080" ring gap is a good illustration about your lack of real knowledge. Despite a link to a racing piston manufacturer PROVING you were wrong, you refused to admit your mistake. Well, I guess you CAN'T admit you're wrong about that, come to think about it - or else you'd owe an engine rebuild to every customer whose engine you rebuilt with those ring specs.

STOP POSTING about things of which you have no knowlege.

PS - I noticed you gave me demerits. I guess that goes hand in hand with tattling to the boss.

 

Stonebreaker: writing in capital letters mean you are yelling at me. Those are really bad manners. There is no proof in the links you provide. They are a manufacturer's claim which according to your recent post are unreliable. I have many years of rebuilding and repairing engines. My customers, with few exeptions, are satisfied and willing to recomend my services. At this point your posts are constituting libel and I request you stop them.

 

No. Any time I see something I know is wrong, I will shoot it down. If you don't want me to shoot down your posts, all you have to do is check your facts first.

 

Stonebreaker: While I sympathize with your intent, your last few posts have indeed been awfully rude and yes, they are starting to sound libellous. Your post history indicates similar things have occurred elsewhere on the forum too. You claim that you are not a mechanic or racer, yet see a need to ream out a professional engine builder? Please be a bit more civilized in future and read your paragraphs over a few times before you click "PostQuickReply".

 

No, I AM a racer - that's why I know what I'm talking about. I've expedrimented with different combinations till I determined which one works best. As far as libel, exactly what was libellous? Point to it. I've been on the car forums long enough to know that the bad info gonzo and others are propogating will be accepted by newbies as gospel if it's not corrected. I tried being nice, he didn't take the hint, so I did the same thing I'd do to a puppy who kept crapping in the house - I rubbed his nose in it. I will continue to do so until he learns. I don't understand why it bugs you to see someone corrected.

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I don't try to tell people how to design hulls - that's why I joined this forum, cause I want to learn how to do that. However, if the hull info has as many bad posts in it as the engine posts, and people are discouraged from correcting the bad info as I have been when correcting bad engine info, how am I supposed to be able to tell which is good info and which is crap?

You guys want some good engine info from guys who have actually dropped automotive engines in their boats, go here. I found them last night when I was surfing for other forums who are more interested in determining actual facts instead of stroking the egos of the forum good ol' boys.

 

You want to find out just how full of crap some of the stuff on this forum truly is, talk to these guys: http://www.bankspower.com/on_the_water.cfm

I'm sure the tech guys would be glad to talk to you, especially seeing as how they are an OEM for GM.

 

Your jawbone?