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Repower 454 Crusaders

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sawade

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I have a 92 Silverton Aft Cabi

I have a 92 Silverton Aft Cabin. I need to repower it because of a cracked head etc. Problem is Crusader doesn't make the carbed 454 anymore. My mechanic says the 8.1 won't fit into the current footprint. Has anyone run into this before - can I go with the 350's or would the boat be underpowered. Current engines are 454XL 320HP - Issue with the tight fit is the way the gas tanks sit on the outboard side. I do not want to modify them. Suggestions?
 
"The 8.1 will bolt right in.

"The 8.1 will bolt right in. You will need to reroute the fuel line, but that's it. Also, if you were carb., you may not have return line fittings in your tank. If this is the case you will need to go with Crusader's returnless fuel system. The motors are sold as return system or returnless systems.

Keep in mind that the 8.1 requires 2" more of exhaust height than the 7.4 this is to keep the water out of the engine. I would add as many 3" riser kits as you can get under the floor.

The bell housing will bolt up as well so there is no need to replace the gears. Buy the motors as "Bobtail" versions. I would recommend you have the gears gone over while you have the boat apart.

You may need to have your props tweaked also due to the change in HP, but I would wait until you run the boat first.

Good luck
Rick"
 
"Maybe I didn't state it c

"Maybe I didn't state it clearly enough. Because of the limited space in this particular boat (Silverton 34 Aft Cabin), the newer motor is a bit too wide at 33". With the 454 the outboard manifolds and exhaust were very close to the gas tanks - I really have no room to spare. the 8.1 is wider - I have to believe that these very popular models are being repowered - if so how?"
 
"The manifold on the 8.1 will

"The manifold on the 8.1 will be .69" closer to the fuel tank than the 7.4. That's less than 3/4". As long as they are not contacting the tank a heat shield could be fabricated to protect the fuel tank. I have repowered the Silverton 37C as well as the Mainship 37 aft cabin with 8.1s. The Mainship is very similar to the Silverton and I have had no problems on either one.

If you don't have 3/4", go with the 6.0L engines. The 6.0 is 27.6" wide and produces 375 hp. It is lighter and more powerful than your original 7.4."
 
You might want to consider goi

You might want to consider going with another 454 retrofitted with a more efficient roller cam and aftermarket roller lifters. This combo works good with the stock oval or rect. port heads.
 
Will the 6.0L be strong enough

Will the 6.0L be strong enough - some people have told me its the torque I need to worry about not the HP. I would prefer to go that way rather than modify the tanks or the boat in any real way?
 
"Sure. The 6.0 is a 5300 RPM

"Sure. The 6.0 is a 5300 RPM engine. You will most likely be reducing the prop size to get the RPMs up where Crusader wants them to be. This change will give you the thrust and the low end torque you are looking for. The new Silverton 36C comes with 6.0s standard and that boat runs great with them. The 35MY (aft cabin) does use the 385 hp 8.1 as standard but that boat is 40'2" long and weighs 22,000 lbs.

If you're unsure, you can still buy a new 7.4 longblock from Crusader. It will be a GenVI, so you will need to add the electric fuel pump kit and make some other minor updates, but it will work using your old bolt-ons. Rick"
 
"I like the idea of fuel injec

"I like the idea of fuel injection and am not really interested in going back to the older style carborated engine if I am spending all this money on an upgrade. My boat weighs 16,000 lbs and is a shade less than 40' LOA including the pulpit. I guess I will try the 6.0L engines. You wouldn't happen to know the torque specs on the 454/320 vs this new engine would you?
And thanks for the help"
 
"Be darned if I'd run an e

"Be darned if I'd run an engine that has to be reved at 4,400 rpms, like that 6.0 Vortec, to achieve its peak mid-range torque! Fine for a muscle boat but little else.

Jeff"
 
Don't disagree- what I am

Don't disagree- what I am going to do is have my gas tanks redone to give me the 2" I need on both sides of the boat and then install the 8.1's. As it works out anyway the 6.0's are taller than the 454 or 8.1 and would require some boat reworking to fit anyway.
 
"Steve,

Do yourself a favor

"Steve,

Do yourself a favor and have new tanks made. Florida Marine Tanks still has the drawings for your original tanks and can make you a new pair modified to meet your needs.

Your tanks are 15 years old. When your welder cuts them apart to modidfy them he will see that they have started to corrode from the inside. They were only .125" when new and he will have problems with burning through, especially at the bottom. You will need to remove them anyway and I feel going new is a wise move and well worth the extra money."
 
Thats the plan - actually it w

Thats the plan - actually it was only $1K difference between the labor of cutting or replacing - What's $1K after replacing both engines.
 
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