F20B build r/s crank and piston question
02-28-2014, 12:28 PM
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F20B build r/s crank and piston question
Alright guys, Im 18 and building my first turbo motor. i have built several D/B/H motors for N/A, but for this i need a little help. I am building an F20B for boost. shooting for around 400+ hp. now, i will be using a stock F20B block (85mm cylinders). i am going to be using an H22a4 crankshaft and forged rods. along with F22A forged pistons. now i need a little help determining what the compression is going to be, and what the rod/stroke will be,and if everything will work. ive already tried searching this but there is no definitive answer as far as i can tell. all i know for a fact is i can put an a4 crank in an f20b block. here are as many specs as i can find
F20B Deck height- 8.643
F20B bore - 85mm/ 3.346
H22a4 rod length- 5.633
F20B rod length-5.709
compression height on stock F20B - 1.221
H22a4 stroke - 90.7mm/3.570
F20B stroke - 88mm/3.464
assume im using a stock head gasket and like i said i am boosting this engine. and i am doing it on stock sleeves. and what F22A pistons will i need to make sure i will have low compression?
thanks guys!
F20B Deck height- 8.643
F20B bore - 85mm/ 3.346
H22a4 rod length- 5.633
F20B rod length-5.709
compression height on stock F20B - 1.221
H22a4 stroke - 90.7mm/3.570
F20B stroke - 88mm/3.464
assume im using a stock head gasket and like i said i am boosting this engine. and i am doing it on stock sleeves. and what F22A pistons will i need to make sure i will have low compression?
thanks guys!
02-28-2014, 03:33 PM
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Re: F20B build r/s crank and piston question
Using a stock compression F22a piston you will get around 7.7-8 compression when using the parts you have stated above. So you may need something around a 12:1comp F22a piston to get a 9ish compression ratio with you set up. I use this site for a basic idea of how to calculate http://www.zealautowerks.com/hfseries.html
03-01-2014, 11:14 PM
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Re: F20B build r/s crank and piston question
Awesome thank you very much! and is there like a perfect rod/ stroke ratio? and with this set up, do you think revving it to 8000 will be fine for the motor? it will have a built head as well.
03-01-2014, 11:27 PM
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Re: F20B build r/s crank and piston question
stop focusing so much on r/s ratio, unless this is a race car it doesnt matter as the motor wont spend enough time t high rpm levels for it to matter
just build the motor however you want and enjoy it.
another option instead of f series pistons is to use k20 forged pistons, they are a direct replacement aside from being 1mm larger (86mm vs 85mm). this is also a good option because k20 pistons are shelf stock whereas most f series pistons are made on an individual order basis (normally)
you may want to consider an f22 head if possible, in stock form they flow more than a street ported b series vtec head and parts are cheap (delta sells cam regrinds for less than 100 dollars) the f20b head isn't all that great IIRC
ultimately the cam and intake manifold will limit you, look into a k20 intake manifold (direct bolt on replacement for f series motors)
just build the motor however you want and enjoy it.
another option instead of f series pistons is to use k20 forged pistons, they are a direct replacement aside from being 1mm larger (86mm vs 85mm). this is also a good option because k20 pistons are shelf stock whereas most f series pistons are made on an individual order basis (normally)
you may want to consider an f22 head if possible, in stock form they flow more than a street ported b series vtec head and parts are cheap (delta sells cam regrinds for less than 100 dollars) the f20b head isn't all that great IIRC
ultimately the cam and intake manifold will limit you, look into a k20 intake manifold (direct bolt on replacement for f series motors)
03-03-2014, 08:47 AM
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Re: F20B build r/s crank and piston question
stop focusing so much on r/s ratio, unless this is a race car it doesnt matter as the motor wont spend enough time t high rpm levels for it to matter
just build the motor however you want and enjoy it.
another option instead of f series pistons is to use k20 forged pistons, they are a direct replacement aside from being 1mm larger (86mm vs 85mm). this is also a good option because k20 pistons are shelf stock whereas most f series pistons are made on an individual order basis (normally)
you may want to consider an f22 head if possible, in stock form they flow more than a street ported b series vtec head and parts are cheap (delta sells cam regrinds for less than 100 dollars) the f20b head isn't all that great IIRC
ultimately the cam and intake manifold will limit you, look into a k20 intake manifold (direct bolt on replacement for f series motors)
just build the motor however you want and enjoy it.
another option instead of f series pistons is to use k20 forged pistons, they are a direct replacement aside from being 1mm larger (86mm vs 85mm). this is also a good option because k20 pistons are shelf stock whereas most f series pistons are made on an individual order basis (normally)
you may want to consider an f22 head if possible, in stock form they flow more than a street ported b series vtec head and parts are cheap (delta sells cam regrinds for less than 100 dollars) the f20b head isn't all that great IIRC
ultimately the cam and intake manifold will limit you, look into a k20 intake manifold (direct bolt on replacement for f series motors)
03-03-2014, 05:00 PM
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Re: F20B build r/s crank and piston question
this is a race car, and It needs to be perfect as it will be daily drivin, I am using a sheepey tubular manifold and a Holset H1C turbo looking for around 450-500whp (with a small shot of nitrous that I already have in my car) to spool the turbo. I would like the leave the cylinders stock bore as I will not be sleeving the block. and using an f22 cylinder head on a dual over head cam block is completely pointless. the f20B head flows much better than any single cam head. and it will be port and polished with valves, springs, retainers and turbo cams. also I will be utilizing a k20 rbc manifold that I picked up yesterday as my intake manifold of choice along with the k to h adapter plate to make it compatible with the cylinder head.
You dont want to put stock sized pistons in any block, always get true cylinders with a .5mm over. I ve seen a handfull be ok, most of them smoke horribly. Any real engine builder knows that.
Also, 500whp isnt fun for street cars, spin city. I tried it for a while in my 1.8, eventually turnd it down to 330-350 for street, 500-525 at the track.
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03-03-2014, 08:33 PM
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03-03-2014, 08:36 PM
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Re: F20B build r/s crank and piston question
Hes right about a certain f22 cylinder head, they do flow better than b series.
You dont want to put stock sized pistons in any block, always get true cylinders with a .5mm over. I ve seen a handfull be ok, most of them smoke horribly. Any real engine builder knows that.
Also, 500whp isnt fun for street cars, spin city. I tried it for a while in my 1.8, eventually turnd it down to 330-350 for street, 500-525 at the track.
You dont want to put stock sized pistons in any block, always get true cylinders with a .5mm over. I ve seen a handfull be ok, most of them smoke horribly. Any real engine builder knows that.
Also, 500whp isnt fun for street cars, spin city. I tried it for a while in my 1.8, eventually turnd it down to 330-350 for street, 500-525 at the track.
even when going forged at stock bore sizes normally enough material has to be removed for proper p2w which normally trues the bores... if you don't run a lot of p2w then you don't remove enough material
however I would never run a forged motor with less than 40thou p2w
03-04-2014, 07:51 AM
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Re: F20B build r/s crank and piston question
Ok so what about this option? What if i call weisco and order custom pistons that will be about 9:1 c/r for the stroke and rod length i have. And get it at 85.5mm and can a macheine shop bore it out only .5? To make it a true straight cylinder? And would it be a good idea to get the pistons made and then take the piston to the machine shop so they can match the bore perfectly? And we shall see what this turbo will make, like a said. Hopeing for 450 but we will see what it acutally makes
03-04-2014, 08:19 AM
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03-05-2014, 09:47 AM
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Re: F20B build r/s crank and piston question
Ok so I'm just going to have weisco make me some custom pistons for my application. Do i need f20b main bearings? Or h22a4 mains?
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