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Big cubic inches or blower for 650-700 hp? Carbed or fuel injected?

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Big cubic inches or blower for 650-700 hp? Carbed or fuel injected?

Old 10-27-2017, 10:02 AM
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The boat came with a 177 blower and has holes in the back of the seats for those tiny pulleys. So someone tried. No way was I wasting time with that small of a blower on a 540.
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Old 10-27-2017, 02:01 PM
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Blowers get my vote.

Only reason blowers are labeled problematic , is not because of the blower sitting on top. It's because of the builder. Sorry, but if you have blower engines and they are constantly breaking, it's time to find a new builder.

I have 468s making over 800hp , that idle all day long at 700rpm in gear, and scream to 6200rpm without as much as a hiccup. Basic Mark IV 454 blocks, GM forged cranks, hydraulic roller, etc. Nothing fancy. Try making 800hp with a NA 468, and you'll have a race fuel, non idling, 7500rpm untamed beast that will launch valvetrain pieces after a few passes across the lake. I am pushing the envelope a bit , but I'm good with that. If longevity was the goal, I know I could turn the boost down to 4lbs, make 675-700hp, but what fun is that
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Old 10-27-2017, 02:16 PM
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Did someone say scorpion rocker failure ?
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Old 10-27-2017, 02:19 PM
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I thought scorpions were one of the best.What is the next alternative
jessel?
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Old 10-27-2017, 02:26 PM
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..

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Old 10-27-2017, 02:32 PM
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Originally Posted by turbos230
I thought scorpions were one of the best.What is the next alternative
jessel?
I don't know about all that ....being "one of the best "....crower makes a great steel rocker and comp cams Ultra XD rockers...crane retooled their gold rockers , but I haven't seen the new versions yet
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Old 10-27-2017, 03:15 PM
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Originally Posted by cdail28590
Not quite the 650hp as asked for but my 454 with good internals, hyd roller cam, 177 blower and stainless marine manifolds make 610 hp and starts and runs like a fuel injected motor. I would say not a high dollar if you already have the parts like I did but with better heads and a 502 you could easily hit the 700 hp and be very reliable.
Which cam are you running? Exhaust wet or dry? I got 572 hp with stock 454 mag longblocks, 177's, single 800dp, flat tappet cam and wet emi exhaust.
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Old 10-28-2017, 09:37 AM
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My advice to you is to get a dyno program and punch in some normal specs with a cam that will not revert and see how much torque you will be making at the top rpm you want to run it.

Then switch the program to a supercharger with 8 lbs and lower your compression and see which will do what you need it to do.

Ps Forget about hp numbers and concentrate on the torque in the rpm you want to rev it to..Hp is a formula of torque and rpms.
You could have an engine that makes 800hp but makes torque to low to get on plane and in the range you would be using it.Which is worthless.
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Old 10-28-2017, 05:50 PM
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So!

opinions are not all the same!! Good points to both recipe!

Still not clear to me!

guess it depends on what the engine builder you work with prefers!

thanks for talking about all those good opinions!
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Old 10-28-2017, 09:56 PM
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Originally Posted by Warship2k15
My advice to you is to get a dyno program and punch in some normal specs with a cam that will not revert and see how much torque you will be making at the top rpm you want to run it.

Then switch the program to a supercharger with 8 lbs and lower your compression and see which will do what you need it to do.

Ps Forget about hp numbers and concentrate on the torque in the rpm you want to rev it to..Hp is a formula of torque and rpms.
You could have an engine that makes 800hp but makes torque to low to get on plane and in the range you would be using it.Which is worthless.
Also, factor in the type of boat. A 35 Fountain, might not like the same engine as a single engine 29 fountain.

We must remember that we have an outdrive and prop that acts like a gear ratio. Let's say you build an engine for max low and midrange numbers. And setup to spin 5000rpm. You turn a 30p prop to 5000rpm with a 1.5 gear ratio.

Now you build another version of that same engine, that trades off some low rpm power, for upper rpm power, and can rev to 6000rpm. Can turn a 26p prop say, to 6000rpm. Even though you gave up some midrange or low rpm power, you may find the boat accelerates and planes better, with the 26p prop setup, vs the 30p low rpm stump puller engine.

It's like comparing a car , say with a LS small block and a 4.10 rear end, to a big block with a 3.08 rear end. Just because you're making more torque at a lower rpm, doesn't always equate to faster acceleration, or even more efficiency . In semi truck world, for getting an 80k lb rig from 0-60, I'll take a 350hp with a 13spd and 4.30 rears, over 450hp with a 8spd and 3.55 rears any day of the week.

Take a look at Bob teagues amsoil boat with its 500 inch Supercat engines that rev to 7k plus, certainly not low rpm stump pullers, but they have no problem coming out of a corner ,putting it on the limiter and coming up to speed in a hurry.

If fuel efficiency is a big concern, focus on the hull . A cat or efficient vee bottom, is gonna get much better fuel mileage than a heavy old deep vee. A pair of 750 carb engines in a cat cruising at 65mph, is gonna get better mileage than a heavy straight bottom deep vee with a pair of 525s. It takes HP to push a boat thru the water at xxx speed. It takes x amount of fuel to make x amount of HP. I've seen guys spend tens of thousands on custom efi setups and super efficient engines , chasing fuel economy from their boat , when they should have just got a modern stepped boat for what they spent.
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