454 Mag Intake Manifold Questions...
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Are you building the engine yourself? Talk to Dean over at Gellner Engeering if your looking for a builder. It's amazing how much HP he can extract out of a NA 454. The setup works well, Their work is like no others. I have roughly around 230 hard hours on her and It is still running solid. Recently did a compression check, still running 150PSI each cyl.
My Setup:
454 Block
Stock Bore
JE 9.6:1 Compression
Stock Rods
Blue printed & Balanced
CMI Headers
Roller Rocker Lifters
Hdyro Cranscam
Holly 850CFM Carb
Dart Hi Riser intake manifold
Dart 454 Heads
Dyno 514hp (conservative tune)
My Setup:
454 Block
Stock Bore
JE 9.6:1 Compression
Stock Rods
Blue printed & Balanced
CMI Headers
Roller Rocker Lifters
Hdyro Cranscam
Holly 850CFM Carb
Dart Hi Riser intake manifold
Dart 454 Heads
Dyno 514hp (conservative tune)
#12
Emerald Coast of Florida
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#13
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[QUOTE=Senza Spectre Man;2062242][QUOTE=PatriYacht;2061014]
How much hp do I give up using the RM's vs dry headers? Isn't engine compartment heat an issue with dry headers? The additional money needed for headers I'm planning on using to buy hydraulic steering.
I'd say about 50hp lost due to lost scavenging and other inefficiencies of the manifold. I'd guess good for 2 mph.
"Dry" headers are still water jacketed and cooled, just the water doesn't mix within the exhaust gas stream. That can cause reversion with the right combo of parts.
You are doing things in the right order; steering first then more speed. I went the other way and am lucky to have dodged a bullet or two. Add on hydraulic external steering is going on now.
If this is your first performance boat engine, take a little advise and install an oil temp sender and guage.
BT
How much hp do I give up using the RM's vs dry headers? Isn't engine compartment heat an issue with dry headers? The additional money needed for headers I'm planning on using to buy hydraulic steering.
I'd say about 50hp lost due to lost scavenging and other inefficiencies of the manifold. I'd guess good for 2 mph.
"Dry" headers are still water jacketed and cooled, just the water doesn't mix within the exhaust gas stream. That can cause reversion with the right combo of parts.
You are doing things in the right order; steering first then more speed. I went the other way and am lucky to have dodged a bullet or two. Add on hydraulic external steering is going on now.
If this is your first performance boat engine, take a little advise and install an oil temp sender and guage.
BT
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It will definitely negate the brass. I'm worried that the inserts might move around from the heat cycle during ceramic coating. No worries though, I'm buying an automotive version. Thanks for your help!
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If you don't mind me asking, what where the bullets? It's good to know what to look out for. Thanks for the advice about adding an oil temp gauge. That makes sense, a marine engine is under constant load, so I would think you'd get some hot spots and elevate oil temp. I've also built quite a few 911 engines. Oil temp is critical on those.
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Several years while flying thru the air off a cruiser waker at wot one engine stopped mid flight (metering rod jumped out of jet on qjet). Hard right turn on landing plus small scary fire.
Two years ago huge wave again. Hit at wot with too much positive trim. Got huge bow high air and came down slightly crooked which resulted in a wicked right hand turn. This one nearly pitched me out but my bolsters held and my steering held under extreme load. Definately a turning point for me there!!
Last year I twisted off a prop shaft in rough seas at wot. That one was fairly uneventful in fact I never lost plane and used the tabs to run it level the 10 or so miles back to port.
I run way too hard to not have hydraulic steering!!
Most important tip I would have is at 75mph + use positive trim conservatively off large waves. Too much bow air can result in a barrel roll on reentry if you are off keel a little and skip first off your transom. Boat can do a bit of a piroette. Only thing that can help at that point is good steering and solid bolster seats when she comes down.
BT
Two years ago huge wave again. Hit at wot with too much positive trim. Got huge bow high air and came down slightly crooked which resulted in a wicked right hand turn. This one nearly pitched me out but my bolsters held and my steering held under extreme load. Definately a turning point for me there!!
![EEK!](/forums/images/smilies/eek.gif)
Last year I twisted off a prop shaft in rough seas at wot. That one was fairly uneventful in fact I never lost plane and used the tabs to run it level the 10 or so miles back to port.
I run way too hard to not have hydraulic steering!!
Most important tip I would have is at 75mph + use positive trim conservatively off large waves. Too much bow air can result in a barrel roll on reentry if you are off keel a little and skip first off your transom. Boat can do a bit of a piroette. Only thing that can help at that point is good steering and solid bolster seats when she comes down.
BT
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