Returntrip
Contributing Member
Good morning, I havent had time to be on the Forum lately,
Rick, I have been on the phone with 9 different machine shops in the last 2 weeks, 7 of them specializing in marine engines. Im trying to figure which way to go with this engine build (especially piston profile).
I have explained to them in detail the varied information I have gotten about piston profile vs. comb.chamber profile, location of peak cylinder pressure, cam dynamics & and quality and types of rotating assembly components.
7 out of 9 totally are for the LCQ style build (one of them automotive machine) 1 said either way would work O.K. (whats O.K.?) and 1 shop said he has used flat tops or relieved cut pistons because thats what he has seen when disassembling marine engines.
After much research and consideration I will be going with your suggestion with the piston design you have laid out in detail to hopefully build a durable, efficient engine with very good torque. I have also opted out of the Bowtie Vortec heads & went with the AFR 195 cylinder heads, whth added inconnel exhaust valves installed. These heads have a 77% flow rate which is much higher than most and will give me a better choice on setting up the correct cam profile i want. Here is a list of some of the parts I will be using if it helps anyone at all. (Noting 1st. of all, this is not a low budget build.
(1) Mahle phosphorus coated forged pistons. (9.1) comp. Explanation, hypereutectic pistons would have been strong enough, BUT... if one fails, a hypereutectic piston will shatter like glass and surely lead to catastrophic engine failure. Whereas a forged piston will most likely stay together.
(2) Scat pro comp forged 7/16 connecting rods. (already are designed with clearance in mind for stroker application.)
(3) Forged internally balanced cross drilled crankshaft. (Lighter weight for rotating mass)
(4) High volume oil pump ( not high pressure)
(5) Roller camshaft, & valvetrain (specs to be determined) cyl. head flow #s and lift specs. will dictate final camshaft selection.
(6) Closed cooling system (extremely important for longevity, especially with any aluminum components)
(7) Many hours of oil clearance and porting work to improve & re-direct oil flow, even on pump main cap and pump. Always check, even new pump rotors were slightly out of spec. like mine. Must do serious reading on pump mods to be done correctly.
(8) Time, patience & cleanliness.
(9) Listen to everyones suggestions, and research.
I truly appreciate everybodys input. I am fortunate I dont have a strict budget to stick with. I have been laying on my back and been on my knees (Dont take that the wrong way) in the engine room, bilge or deck of boats for decades (mostly diesel), Im in my late 50's and do not particularly care to do a job more than once. I know there is a multitude of things I didnt mention or list. I am also sure there may be people that dont agree with some or any of my decisions. Upon completion of this build I will provide a detailed list of components used, and this spring and throughout the summer will give updates on performance of this build.
Im sure i will have many more questions along the way, building the engine is only one component of safe, reliable, enjoyable boating. I not only enjoy boating but I use mine for transportation. Im sure we are all on this forum because at one time or another, we had an allure to the water, a passion for boating and working with our hands.
I want to thank everybody so far, especially Rick for all your input. I look forward to hearing from people with comments & suggestions. Thanks, Johnny V.
Rick, I have been on the phone with 9 different machine shops in the last 2 weeks, 7 of them specializing in marine engines. Im trying to figure which way to go with this engine build (especially piston profile).
I have explained to them in detail the varied information I have gotten about piston profile vs. comb.chamber profile, location of peak cylinder pressure, cam dynamics & and quality and types of rotating assembly components.
7 out of 9 totally are for the LCQ style build (one of them automotive machine) 1 said either way would work O.K. (whats O.K.?) and 1 shop said he has used flat tops or relieved cut pistons because thats what he has seen when disassembling marine engines.
After much research and consideration I will be going with your suggestion with the piston design you have laid out in detail to hopefully build a durable, efficient engine with very good torque. I have also opted out of the Bowtie Vortec heads & went with the AFR 195 cylinder heads, whth added inconnel exhaust valves installed. These heads have a 77% flow rate which is much higher than most and will give me a better choice on setting up the correct cam profile i want. Here is a list of some of the parts I will be using if it helps anyone at all. (Noting 1st. of all, this is not a low budget build.
(1) Mahle phosphorus coated forged pistons. (9.1) comp. Explanation, hypereutectic pistons would have been strong enough, BUT... if one fails, a hypereutectic piston will shatter like glass and surely lead to catastrophic engine failure. Whereas a forged piston will most likely stay together.
(2) Scat pro comp forged 7/16 connecting rods. (already are designed with clearance in mind for stroker application.)
(3) Forged internally balanced cross drilled crankshaft. (Lighter weight for rotating mass)
(4) High volume oil pump ( not high pressure)
(5) Roller camshaft, & valvetrain (specs to be determined) cyl. head flow #s and lift specs. will dictate final camshaft selection.
(6) Closed cooling system (extremely important for longevity, especially with any aluminum components)
(7) Many hours of oil clearance and porting work to improve & re-direct oil flow, even on pump main cap and pump. Always check, even new pump rotors were slightly out of spec. like mine. Must do serious reading on pump mods to be done correctly.
(8) Time, patience & cleanliness.
(9) Listen to everyones suggestions, and research.
I truly appreciate everybodys input. I am fortunate I dont have a strict budget to stick with. I have been laying on my back and been on my knees (Dont take that the wrong way) in the engine room, bilge or deck of boats for decades (mostly diesel), Im in my late 50's and do not particularly care to do a job more than once. I know there is a multitude of things I didnt mention or list. I am also sure there may be people that dont agree with some or any of my decisions. Upon completion of this build I will provide a detailed list of components used, and this spring and throughout the summer will give updates on performance of this build.
Im sure i will have many more questions along the way, building the engine is only one component of safe, reliable, enjoyable boating. I not only enjoy boating but I use mine for transportation. Im sure we are all on this forum because at one time or another, we had an allure to the water, a passion for boating and working with our hands.
I want to thank everybody so far, especially Rick for all your input. I look forward to hearing from people with comments & suggestions. Thanks, Johnny V.
