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motor advice

stclairriverblaster

stclairriverblaster

Member
ok so as some of you know i have a .60 over 454 block that took a dump.. two gouges in the back cylinders... also i discovered trashed bearings so the crank isnt too hot..

main question is... is it safe to go 1.0 over? also is it safe to get the crank repaired or am i better off getting new..
theres no discoloration on the crank.. just some uneven wear.
also whats the max power i can make on a stock 454 block without worrying about the block splitting or cracking.... lets say .20 over bore


plans are to get new pistons 13.1 run e85 keeping the cam i have since it will be fine with higher than the 7.1 compression i had.
 
OK now it will be on the right post! lol Jazzy has a 502 procharger motor take out . You might want to see what he wants for it.
 
I think you can safely go .100 over on a 454 but would not go more than .060 over myself. Sonic testing can determine wall thickness. Also CR of the engine would effect my final bore size. I could be wrong but each series and engine dates are different.
 
Since you asked, My opinion is you are working with junk and trying to patch it back together, with sleeving the block and boring it to the max your wasting your time and money. if you want to run a 13:1 motor on a repaired crank,It will be a short live engine. I take it you would have it welded and ground. And if it's a 4340 crank it needs to go in the trash if it's that bad.
My advice is to build a marine engine and get away from the automotive mentality.
Find a good used block, a new crankshaft and start from there.
 
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i was planning on getting a new block.. and keeping the bore small .20 over max..

the crank i had no clue about. i know with the mitsubishi motors the crank is hardened and cannot be turned or repaired. otherwise failure is immenent ..

so my shopping list is new block crank and pistons..

oh i forgot it will be a closed loop cooling system. and will be machined tighter i see that being beneficial to longevity at high rpm useage..
 
The same advice I gave Gimmefuel, buy a used stock drop in motor, they can be found on Craigs list often, get a 454 or a 502 and go boating. You will save money in the end and actually have time in the boat instead of beating your head aginast the wall in the garage. It will also help with the resale of the boat not having a Franken-motor. Just my $0.02
 
I agree with Red, A high rpm engine is machined much looser. A high rpm engine is set up loose in order to gain the rpms and power but don't have the longevity of a normal engine. That is why Nascar and other racing engines only last for short distances before being torn down and gone over.
 
stclairriverblaster said:
my understanding of loose machining tolerances on marine motors is because of the cooling system.. the block doesnt fully expand.

am i wrong?
Click to expand...


Your right about that, piston to wall clearance should be no less than .004 no more .006. the bigger the engine and rpm limit the more clearance I put in them up to.006.
I think the term is closer tolerances. The crank and rods should be checked close to make sure they have all the same oil clearances I like to see .002 no more than .003 on both.
I like to see my rod side clearance at about .018" this keeps the oil in the rods and maintains good oil pressure. crank end play is overlooked by a lot of shops. long as it spins its good they think. I like to see .004 to.006. This also helps maintain oil pressure and reduce side load on the rods. It's more work to get all these tolerances right that's one of the reason a Marine engine cost more to machine if it's done right.

Your right the crank can't be welded because of the hardening,

So new block and crank is the way to go. and no more than 10:1 compression, unless you want to run race fuel all the time and pay up the a$$ for it. There are other draw backs with that kind of compression That I won't go into. With the right Marine cam it will run just as good with 10:1
 
the fuel i am gonna be running is e85 has a knock rating of around 108 octan iirc and is cheaper than premium. also burns cooler.
the boat will be trailerd to the lake.. ran for a few hours and returned home and tank will be basically empty.. no excess fuel sitting around soaking up water..
 
so can someone explain to me why a slightly tighter bore machining process and closed loop cooling is a bad idea? i really dont see any downside to it.. all these high hp cars i see built are built with tighter than marine tolerances and they last quite awhile..
the only reasoning i see for the looser bore tolerances is because of the variances you can have in water/block temp.
the max rpm i plan on running is 5800-6000 i mean obviously until lately boats have been way behind in technology compared to cars.
 
stclairriverblaster said:
the fuel i am gonna be running is e85 has a knock rating of around 108 octan iirc and is cheaper than premium. also burns cooler.
the boat will be trailerd to the lake.. ran for a few hours and returned home and tank will be basically empty.. no excess fuel sitting around soaking up water..
Click to expand...


First e85 is not USCG approved, It runs hotter in a marine engine not cooler.
If contaminated it' mixes with water and does not separate,gums carburetors,eats rubber fuel lines, burns valves due to constant wide open running ,eats fiberglass, It is designed for flex fuel vehicles that are designed to use it, not Marine engines. They don't sell it everywhere. and not at fuel docks.
So why would you want to spend the money on a nice engine then gamble with inexpensive
fuel not formulated for marine use.

Like I said you have to get off the automotive mentality,
 
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