Bbc 454 gen 4 overhaul
 

The first thing you will need is good exhaust with longer risers.

Here is an OLD thread with good info. https://www.offshoreonly.com/forums/...ing-griff.html
To get to 450+ hp, use a Crane 168731 roller cam, Holley 800cfm #9022 carb and some mild port work on the heads.

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So in other words I can buy any 454 rebuild kit and slap the extra suggested parts on it and meet my goals

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Reason I'm asking i was told marine wise by a local engine shop that I have to bore .60 over to meet those goals i can just bolt an equation of parts together and get it with stock bore

I made 527hp/517tq on a stock bore 454.9.5-1 compr,flat tappet cam 230/236 ls110 .575" lift victor jr w/ a 930cfm carb.my sutphen ripped w/ that combo.eventually I ended up w/ a cam in the 250ish duration.:D

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That is awesome I bet that is sweet ride I'm really glad to hear that I'm a newbie at the performance boating game but would love to do all the work my self instead of paying a shop out buying a motor

Boring .060 alone adds very little hp. Maybe 2%. You might need to bore it .030 to clean up the walls, but no reason to .060 unless its needed.

You bore it .060 and you're done. Anything else goes wrong your out a block or have pay to sleeve it. Not worth the meager performance gains. Boat motors are like any other high-performance engine, except TQ is about as important as HP, and more important for both is where they come in. Building something that make 600hp on the dyno at 7000 rpm is nearly useless in a boat. Think "how do I build as much HP as I can below 6000 rpm". I had two .030 over 454s, well massaged 049 iron heads, 9.2 compression, long tube headers and a Comp Cams "special grind" offshore cam, solid rollers, 780 cfm holley and dynoed 502hp at 5800 rpm (390 @ 6200! haha) and over 510 FT/lbs of TQ almost straight across the board. Worked good at cruise, had power out of the hole and could run top-end when needed. 450hp is doable on stock or .030 over bore.

Welcome to OSO. You have definitely come to the right place to ask questions. There's a lot of talented and experienced engine builders that hang out here. I don't claim to be one of them but I've picked up a lot of marine specific info over the years here.

My 29 Fountain has Gen-4 454 mags that were pumped up to ~500HP abt 7 years ago. Fortunately it was all done by the prev owner. Unfortunately I don't have all the specs. Having a mag eng is definitely a plus since they came with forged cranks and larger rod bolts too I believe (7/16"?). IMHO; the additional cubic inches from boring isn't much of a factor in the big picture. I would just have them take out enough to clean it up, If .030" makes the bore round again, I'd stop there. Make sure machine shop uses torque plates when boring.

A quality valve train is a must for extended high RPM operation. My valve train is all Crower and has performed flawlessly. Full roller is best but at least use full roller rockers. Stamped rockers flex and increase oil temp significantly. Exhaust valves take a beating compared to a car/truck eng so those will need to be high quality parts (S/S or inconel)..

Original oil cooler probably won't be able to keep up at WOT, so full throttle runs will be limited to a couple of mins or so until that is addressed. Definitely want an oil temp gauge if you don't already have one. A larger oil pan is a plus if you have the room.

Compression ring end-gap will need special attention since they tend to run hotter than you would see in your average car/truck.

Carb will need to be a marine version for sure. Mechanical fuel pump may or may not be up to the additional fuel flow demands, but that can be dealt with later.

Exhaust will need to be upgraded as prev mentioned to support the additional flow.

Compression ratio will determine what kind of fuel you need. If high octane is not available on the water where you run, that's something to consider. If running high compression, ign sys may need to be upgraded.

A rev limiter of some sort is highly advised since once the prop comes out of the water, there's virtually no load at all.

A wide band O2 (WBO2) is also highly recommended to dial in the mixture and ign timing. Keep that in mind when ordering/installing your new exhaust. Some manuf offer WBO2 bungs already installed in risers but may not be in the right place for your install.

Whenever possible, copy something that is proven to work well in the same/similar application. That will save you a lot of time and money in the long run. Good luck!!

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I guess I have come to the right place you all have brought up awesome points and very helpful info I can't thank u enough now would u choose iron or aluminum heads like of I rebuilt my stock heads or bought new my plan was to buy everything to do a complete stock rebuild other than cam, switch to roller top end, carb and exhaust ? Any thoughts

The stock heads with some minor porting and milling them .020-.030 for a slight bump in CR will be fine to get you to 450+hp. The same heads are used on the HP500, 500efi and 525sc.

Leak down specs
 

What is good and what is bad for my gen 4 454 for % results @ 90 psi of shop air on a cold engine engine is on stand and I am testing each cylinder i know it's supposed to be warm but its out of boat lol any hope

Your wasting your time doing it on a cold engine. Pistons are several thousandths smaller, ring gaps bigger, bore shape is slightly different. Just not a comparable situation.
I had a customer changing valve springs on a cold motor and was worried because so much was hissing by the piston and compressor runner Ng alot. When he was done we fired it and warmed to normal temp. No more hissing past the piston.

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So since engine is out already if bores look good and engine wasn't using oil keep bottom end together v other than reseal everything and freshen up top end

That is what I would do.

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Ok Griff thank u ill get apart build top end and check bottom now ill throw a curve ball what if I decided to bolt on a complete weiand blower setup that's set at 5psi would u still install the cam that u recommended and or would u change up bottom end then

The same cam will work great with a 177. I upgraded to it on my 525SC which is a 454 with a 177 and 1050 carb.

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That's awesome I guess I may go that route I found a deal on a a complete setup for my engine i really don't want to pass it up

Biggest problem with adding a blower is will it fit under your hatch. I wanted to add one when I did my rebuild and there was no way I could get it under the hatch.

subbed! was looking for similar info when i go to pull my 454mag from my donzi! is your set up already carb or efi? my set up is a 2000 efi and still up in the air if i should drop the efi and go carb.

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I do have room yes height wise is ok forward she will be tight for sure

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Nc03gt , mine is carb im sticking with carb mainly because the blower i bought is that setup and I know how to work on carbs more importantly that's what I have that's what I'm staying with that's just my opinion but look at me I'm on here asking questions just like u lol

I think the blower will help get you to your goals pretty easy. I had a .030 over 454 with iron heads and a Blower Shop 250 blower. With 8 to 1 compression it made 550 horsepower at 8 pounds of boost and no intercooler, all with a flat tappet cam. It ran that way for 14 years. This year after the motor ate an exhaust valve seat, I have decided to rebuild it with aluminum heads and bigger cam. Shooting for the 650 horsepower range. Good luck with your 454 build.

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https://cimg1.ibsrv.net/gimg/www.off...8e36be0121.jpg
these are the pistons that are in my engine right now any tips can I clean and reuse these to use with the blower setup I just bought or will these not work I bought a wieand 177 blower with 1050 carb setup to run 5psi

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https://cimg9.ibsrv.net/gimg/www.off...fc57980f98.jpg
Just another pic any help would be awesome

Those are new Sealed Sower 0.030" forged pistons. The engine has been refreshed at one time. They are the Sealed Power replacement for the TRW stock pistons. They should be good for a mild blower application. I wouldn't worry about cleaning the tops of the pistons. Just get the tune right.

Sealed Power

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What do u mean by get the tune right ?

man get a cover or tape of something over that lifter valley! a lot of hard work can be destroyed by a little bit of dirt/trash

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10-4 thanks for the heads up

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Question when u run a blower shouldn't u change pistons to like 8 - 1 ratio

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I can't find any good info stating a good blower build

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Other than being bored .030 are these pistons direct replacement for stock pistons and should I do anything special to run these with a wieand 177 blower

Generally speaking, it means getting ign timing and fuel mixture adjusted across all RPMs, load conditions and temperatures to achieve max power/best driveability while maintaining a degree of margin to prevent damage or accelerated wear.. Also includes adjustments for quick transitions from one power setting to another (similar to an accelerator pump on a carb), This is where the WB02 comes in handy.

Edit: Missed the part abt op using a carb. Either way, same principle.

Not really. It's all about building cylinder pressure. Starting with a little high compression ratio just means a little less boost to reach a give HP goal.

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So if I bought a complete blower setup off a guy on here he had it on a stock gen 4 454 365hp and I rehoned, reringed, rebearing, new oil pump and resealed bottom end went through heads completely and bolted his stuff on i should be ok theoretically speaking

Theoretically yes, but we don't deal in theoretics. It should be close. Tune it properly or don't do it. Also that engine has low-mid 8:1 ratio.
I believe you have the basic platform of the 525sc.

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That's what I was trying to figure out if these pistons were a direct replacement for stock pistons if they were id say that blower setup will work just fine on my engine

Stock compression on a 454mag/365hp is 8.75. You can run 5# of boost with no issues on 93 octane fuel.

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Ok cool thank u , Griff that's what I was looking for sorry to be a pain never built a blower motor rather be safe than sorry also what are the best head gaskets to use and any recommendations on valve springs im redoing the heads today and getting checked at machine shop