crankshaft question
#1
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Car: 1987 irocz28
Engine: 305 tpi
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crankshaft question
I was looking at summit today just dreaming. I was looking at crankshafts and now that I am actually looking at building something i would like to understand what i am building. Most of the cranks for my 305 were 3.48 stroke. But there was one that was 3.00. What is the difference?
I am still up in the air to what engine i would build part of me wants to keep the 305 part of me wants mega power 350.
My understanding is short stroke higher rpms? If thats right would my max hp be reduced versus a long stroke?
I am still up in the air to what engine i would build part of me wants to keep the 305 part of me wants mega power 350.
My understanding is short stroke higher rpms? If thats right would my max hp be reduced versus a long stroke?
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Re: crankshaft question
I hate to put it like this cause so many people all ready says it... BUT Don't waste a single dime on building a 305 engine... You are shooting your self in the foot before you run the marathon race.
The bore and stroke of an engine is what makes it's cubic inch size (displacement)
Displacement means how many cubic inches of air the engine can move with 1 full revolution of the crankshaft .
Displacement = Bore squared (bore X bore), X Stroke, X Pi (3.14), X # of cylinders, / 4
The 305 has a 3.736" bore and a 3.48" stroke
The 350 has a 4.000" bore and a 3.48" stroke
A 383 stroker would be a 4.030" bore and a 3.75" stroke
The 3.00" stroke was used on the old 265, 283 and 302 sbc engines
The 307 and 327 used a 3.25" stroke
The whole short stroke higher RPM thing was true at one time, but with today's parts you can make a long stroke engine rev just as good as a stroke short one. Use the cam, intake and heads to set your power band.
Plus for high RPM you need engine to breath... Small bore reduces more air flow through cylinder.
Building a small bore gen 1 sb is the same as building an engine with asthma. It can not breath good enough
Nothing "mega power" about the 350 really. In stock form some of them had 155 HP, but it is one of the best bases to start with due to the bore size. You can build a 350 from 150 HP to 600 HP, but with a small bore engine like the 305 you will never get that type power out of it and it will cost you more to get power out of it. (mostly the heads, only 1 good set of aftermarket heads are made to work with the small bore size)
The bore and stroke of an engine is what makes it's cubic inch size (displacement)
Displacement means how many cubic inches of air the engine can move with 1 full revolution of the crankshaft .
Displacement = Bore squared (bore X bore), X Stroke, X Pi (3.14), X # of cylinders, / 4
The 305 has a 3.736" bore and a 3.48" stroke
The 350 has a 4.000" bore and a 3.48" stroke
A 383 stroker would be a 4.030" bore and a 3.75" stroke
The 3.00" stroke was used on the old 265, 283 and 302 sbc engines
The 307 and 327 used a 3.25" stroke
The whole short stroke higher RPM thing was true at one time, but with today's parts you can make a long stroke engine rev just as good as a stroke short one. Use the cam, intake and heads to set your power band.
Plus for high RPM you need engine to breath... Small bore reduces more air flow through cylinder.
Building a small bore gen 1 sb is the same as building an engine with asthma. It can not breath good enough
Nothing "mega power" about the 350 really. In stock form some of them had 155 HP, but it is one of the best bases to start with due to the bore size. You can build a 350 from 150 HP to 600 HP, but with a small bore engine like the 305 you will never get that type power out of it and it will cost you more to get power out of it. (mostly the heads, only 1 good set of aftermarket heads are made to work with the small bore size)
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Car: 1987 irocz28
Engine: 305 tpi
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Re: crankshaft question
Well iguess that settles it building a 350 but if i want to turbo it what would be the best stroke. And yes it will most likely be bored to 383
Last edited by racereese; 10-04-2015 at 03:53 PM.
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Re: crankshaft question
you cant just bore a 350 to a 383. you need a longer stroke crankshaft as well like Night Rider327 said. as for a turbo.... there is no "golden stroke crank" that works better then others. build a 383, slap a turbo on there and make sure you are running a forged steel crank, h beam rods, pistons and you will be good to go.
#5
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Re: crankshaft question
you cant just bore a 350 to a 383. you need a longer stroke crankshaft as well like Night Rider327 said. as for a turbo.... there is no "golden stroke crank" that works better then others. build a 383, slap a turbo on there and make sure you are running a forged steel crank, h beam rods, pistons and you will be good to go.
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