THE OFFICIAL Offset Grind thread (offset grinding H/F crankshafts explained)
05-13-2005, 07:46 PM
#1
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THE OFFICIAL Offset Grind thread (offset grinding H/F crankshafts explained)
I get asked questions about offset grinding the H/F crankshafts via e-mail, AIM or PM on a pretty frequent basis. So I’ve decided to put up a "answer all" informative post covering everything you need to know about offset grinding the H22/23 and F22 crankshafts.
What is offset grinding?
An offset grind is a term used to described the act of decreasing the outside diameter of a rod journal by removing material from either the top or bottom (stroke or destroke) while keeping its opposite to grind end untouched. This changes the centerline of the journal increasing or decreasing the actual stroke.
I know that may have been a bit confusing so heres a visual explination:
What advanteges does my H/F crank have when considering offset ground journals?
The advantage of the H/F cranks is the fact that the rod journal diameter is fairly large compared to the rest of Hondas 4 cylinder offerings. You are starting with a diameter of 1.888 as apposed to the B series jorunal diameter of 1.771. You can have the H/F series rod journals offset ground down to the B series journal diameter to increase or decrease stroke by +/- 3mm. Being that the H/F rods (excluding F23) share the same BE width as the B series rods (.935) this will allow you to run any off the shelf or custom length B series spec rod and OE or aftermarket b series rod bearings.
You can take it a step further and increase or decrease stroke by as much as 6mm by going down to the D series (D15) rod journal diameter of 1.654. Being that Hondas D15 uses a rather narrow rod, a custom rod with a BE bore of 1.772 and BE width of .935 would be required along with a set of aftermarket or custom rod bearings.
Here is a break down of the offset grind stroke options and journal diameters for the H/F (excluding F23) crankshafts:
<FONT COLOR="red">H22 crank:</FONT>
84.7 (1.654 journal diameter - destroke) 1.772 BE bore (rod)
87.7 (1.771 journal diameter - destroke) 1.890 BE bore (rod)
90.7 (1.888 journal diameter - stock stroke) 2.008 BE bore (rod)
93.7 (1.771 journal diameter - stroke) 1.890 BE bore (rod)
96.7 (1.654 journal diameter - stroke) 1.772 BE bore (rod)
<FONT COLOR="red">H23/F22 crank:</FONT>
89 (1.654 journal diameter - destroke) 1.772 BE bore (rod)
92 (1.771 journal diameter - destroke) 1.890 BE bore (rod)
95 (1.888 journal diameter - stock stroke) 2.008 BE bore (rod)
98 (1.771 journal diameter - stroke) 1.890 BE bore (rod)
101 (1.654 journal diameter - stroke) 1.772 BE bore (rod)
What are the costs involved with having a crank offset ground?
Your typical crankshaft specialist will charge you on average, around $150-$250. That will usually include micro polishing and balancing however you should not expect the additional services to be included. It is always best to ask prior to bringing your crank in to avoid any surprise expenses later on.
Also, being that the honda H/F series rod journal has a heat treat depth of about .002-.004 it is required that you re heat treat the journals following the offset grind. Heat treating gives the surface and the .004 depth a level of hardness that is a must have. If you are thinking of skimping out on the heat treating I strongly suggest you re think your approach. Taking a short cut on this will ultimately cost you a great deal more than the $100-$180 it will cost you to re heat treat the journals.
What are the downsides to offset grinding my H/F crank?
There are ABSOLUTELY NO DOWNSIDES to offset grinding a crank when done right. Just be smart with it and keep the journals at least the size of the D15 (1.654) rod journal or bigger. Anything smaller is kinda asking for trouble, especially with a motor you plan on beating on.
<FONT COLOR="blue"><FONT SIZE="2">Conclusion</FONT></FONT>
This is a great option for anyone looking to take their build/project a step further than what Honda has given you to work with, all at an affordable price.. Be it FI or NA you are able to take advantage of stroke sizes rangine from 84.7mm all the way up to 101mm (depending on crank and final journal diameter)
I hope this can be of help to you guys
What is offset grinding?
An offset grind is a term used to described the act of decreasing the outside diameter of a rod journal by removing material from either the top or bottom (stroke or destroke) while keeping its opposite to grind end untouched. This changes the centerline of the journal increasing or decreasing the actual stroke.
I know that may have been a bit confusing so heres a visual explination:
What advanteges does my H/F crank have when considering offset ground journals?
The advantage of the H/F cranks is the fact that the rod journal diameter is fairly large compared to the rest of Hondas 4 cylinder offerings. You are starting with a diameter of 1.888 as apposed to the B series jorunal diameter of 1.771. You can have the H/F series rod journals offset ground down to the B series journal diameter to increase or decrease stroke by +/- 3mm. Being that the H/F rods (excluding F23) share the same BE width as the B series rods (.935) this will allow you to run any off the shelf or custom length B series spec rod and OE or aftermarket b series rod bearings.
You can take it a step further and increase or decrease stroke by as much as 6mm by going down to the D series (D15) rod journal diameter of 1.654. Being that Hondas D15 uses a rather narrow rod, a custom rod with a BE bore of 1.772 and BE width of .935 would be required along with a set of aftermarket or custom rod bearings.
Here is a break down of the offset grind stroke options and journal diameters for the H/F (excluding F23) crankshafts:
<FONT COLOR="red">H22 crank:</FONT>
84.7 (1.654 journal diameter - destroke) 1.772 BE bore (rod)
87.7 (1.771 journal diameter - destroke) 1.890 BE bore (rod)
90.7 (1.888 journal diameter - stock stroke) 2.008 BE bore (rod)
93.7 (1.771 journal diameter - stroke) 1.890 BE bore (rod)
96.7 (1.654 journal diameter - stroke) 1.772 BE bore (rod)
<FONT COLOR="red">H23/F22 crank:</FONT>
89 (1.654 journal diameter - destroke) 1.772 BE bore (rod)
92 (1.771 journal diameter - destroke) 1.890 BE bore (rod)
95 (1.888 journal diameter - stock stroke) 2.008 BE bore (rod)
98 (1.771 journal diameter - stroke) 1.890 BE bore (rod)
101 (1.654 journal diameter - stroke) 1.772 BE bore (rod)
What are the costs involved with having a crank offset ground?
Your typical crankshaft specialist will charge you on average, around $150-$250. That will usually include micro polishing and balancing however you should not expect the additional services to be included. It is always best to ask prior to bringing your crank in to avoid any surprise expenses later on.
Also, being that the honda H/F series rod journal has a heat treat depth of about .002-.004 it is required that you re heat treat the journals following the offset grind. Heat treating gives the surface and the .004 depth a level of hardness that is a must have. If you are thinking of skimping out on the heat treating I strongly suggest you re think your approach. Taking a short cut on this will ultimately cost you a great deal more than the $100-$180 it will cost you to re heat treat the journals.
What are the downsides to offset grinding my H/F crank?
There are ABSOLUTELY NO DOWNSIDES to offset grinding a crank when done right. Just be smart with it and keep the journals at least the size of the D15 (1.654) rod journal or bigger. Anything smaller is kinda asking for trouble, especially with a motor you plan on beating on.
<FONT COLOR="blue"><FONT SIZE="2">Conclusion</FONT></FONT>
This is a great option for anyone looking to take their build/project a step further than what Honda has given you to work with, all at an affordable price.. Be it FI or NA you are able to take advantage of stroke sizes rangine from 84.7mm all the way up to 101mm (depending on crank and final journal diameter)
I hope this can be of help to you guys
08-18-2005, 02:30 AM
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Re: THE OFFICIAL Offset Grind thread (Innovation)
i hav got an h22a crank wot rods do i use my standard h22a or do i have to get b series rod??i can also get a h23 crank which is better to use??will the h23 crank fit using the h22a rods??if does will that turn it 2 a 2.3L
Modified by myh22a at 3:54 AM 8/18/2005
Modified by myh22a at 3:54 AM 8/18/2005
08-18-2005, 06:07 PM
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Re: THE OFFICIAL Offset Grind thread (myh22a)
so, you could potential use any b series rod/cast piston combo and alter compression on a stock sleeved motor?
if this is true, i'm suprised i don't hear of this more often.
if this is true, i'm suprised i don't hear of this more often.
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08-18-2005, 08:45 PM
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Re: THE OFFICIAL Offset Grind thread (yOnKiNaToR)
based on this and the specs page Innovation made, if i stroked a h23 crank to 98mm then i could use use the accord f23 rods if the bore was 88mm. that is a rough estimate. i have not done the actual math yet. i could also use modified h23 or h22 pistons probably. at stock compression (of course oversized)
08-19-2005, 09:27 AM
#10
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Re: THE OFFICIAL Offset Grind thread (tarheelsoldier)
You cannot run a shelf F23 rod on an offset ground H-series crank. The H rod journal is .935" wide the F23's is .780". A difference of .155". But you can use various B-series shelf rods and a short piston and end up with decent compression and rod ratios.
and for reference the stock F23 rod is 141mm.
Pirate
and for reference the stock F23 rod is 141mm.
Pirate
08-19-2005, 09:29 AM
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Re: THE OFFICIAL Offset Grind thread (Rosko)
I found it, its 5.551, too long for a 98 mm stroke, and besides that it isnt wide enough on the big end width or pin width.
Custom rods might be the way to go.
101mm stroke and a 88mm piston = 2456 cc's
101mm stroke and a 89mm piston = 2512 cc's
101mm stroke and a 90mm piston = 2569 cc's
I believe this would take a 5.452 long rod and probably some clearancing on the piston skirt.
Custom rods might be the way to go.
101mm stroke and a 88mm piston = 2456 cc's
101mm stroke and a 89mm piston = 2512 cc's
101mm stroke and a 90mm piston = 2569 cc's
I believe this would take a 5.452 long rod and probably some clearancing on the piston skirt.
08-21-2005, 12:14 PM
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I am considering doing the offset grind on my h22a4 crank because its going off to the machine shop anyways.
With a +/-3mm stroke and b-series rods, can I use the stock h22 piston?
Better yet, can I use JDM H22 pistons with 11:1, or is that too large for the deck height.
I am trying to avoid sleeving the block.
Finally, what is the preferred method for heat-treating the crank after grinding and do most machine shops offer this?
Thanks!!
With a +/-3mm stroke and b-series rods, can I use the stock h22 piston?
Better yet, can I use JDM H22 pistons with 11:1, or is that too large for the deck height.
I am trying to avoid sleeving the block.
Finally, what is the preferred method for heat-treating the crank after grinding and do most machine shops offer this?
Thanks!!
08-21-2005, 03:59 PM
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Re: (berkshire40)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by berkshire40 »</TD></TR><TR><TD CLASS="quote">off topic indeed.
Innovation last posted at 4:56 AM 7/18/2005
Really stuck here with the pistons, any help is greatly appreciated.</TD></TR></TABLE>
I think you'll have a problem with wrist pin diameters. If you check out crowers website and look at their rods it will give you the lengths and sizes of all the honda rods.
This might also help:
say your stroke is 95 (stock h23) and your rod length is 5.630 (stock h23)
now you add 3mm of crankshaft stroke, your rod length will need to get shorter by half this amount (1.5mm or approx. .059 in.) so you would need a rod 5.571 long. So basically anything you add to the stroke you will need to subtract half of that from the rod length.
Innovation last posted at 4:56 AM 7/18/2005
Really stuck here with the pistons, any help is greatly appreciated.</TD></TR></TABLE>
I think you'll have a problem with wrist pin diameters. If you check out crowers website and look at their rods it will give you the lengths and sizes of all the honda rods.
This might also help:
say your stroke is 95 (stock h23) and your rod length is 5.630 (stock h23)
now you add 3mm of crankshaft stroke, your rod length will need to get shorter by half this amount (1.5mm or approx. .059 in.) so you would need a rod 5.571 long. So basically anything you add to the stroke you will need to subtract half of that from the rod length.
08-21-2005, 05:28 PM
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Re: (Yield)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Yield »</TD></TR><TR><TD CLASS="quote">off topic - but what happened to innovation anyways. One day he's talking about all this stuff that's getting made for the prelude, next thing he's disappeared.</TD></TR></TABLE>
He got banned again...
He got banned again...
08-21-2005, 06:35 PM
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h22 block blueprint (so far)
stroke: 93.7mm ~3.689in
main journal: 1.771in
rod BE: 1.890 (b-spec)
rod length (c2c): 5.636-0.059 = 5.577 *
Pin End bore: .866 USDM, .864 JDM *
PE width: ?
*unsure about the specs used this calc
Basically im having trouble finding a piston to fit this application. Do I have to have one made or modified?
Modified by berkshire40 at 4:28 AM 8/22/2005
Modified by berkshire40 at 2:22 PM 8/22/2005
stroke: 93.7mm ~3.689in
main journal: 1.771in
rod BE: 1.890 (b-spec)
rod length (c2c): 5.636-0.059 = 5.577 *
Pin End bore: .866 USDM, .864 JDM *
PE width: ?
*unsure about the specs used this calc
Basically im having trouble finding a piston to fit this application. Do I have to have one made or modified?
Modified by berkshire40 at 4:28 AM 8/22/2005
Modified by berkshire40 at 2:22 PM 8/22/2005
08-22-2005, 04:27 PM
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i still cant figure out what piston to run. the b-series spec has a 21mm PE bore from what ive found, and the h22 runs 22mm! i think i need to have a piston made, or over-bore the rod 1mm, but that doesnt sound like a good idea!?
08-22-2005, 06:50 PM
#21
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Re: (Yield)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Yield »</TD></TR><TR><TD CLASS="quote">off topic - but what happened to innovation anyways. One day he's talking about all this stuff that's getting made for the prelude, next thing he's disappeared.</TD></TR></TABLE>
Yeah, kind of interesting.
I'm still waiting for answers in this thread
https://honda-tech.com/zerothread?id=1304279
Yeah, kind of interesting.
I'm still waiting for answers in this thread
https://honda-tech.com/zerothread?id=1304279
08-22-2005, 07:54 PM
#23
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Re: (Sam1am26)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Sam1am26 »</TD></TR><TR><TD CLASS="quote">
He got banned again...</TD></TR></TABLE>
You sure about that?
That would be the what, fourth time for him?!
He got banned again...</TD></TR></TABLE>
You sure about that?
That would be the what, fourth time for him?!
08-22-2005, 08:05 PM
#25
Member
Re: (vinuneuro)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vinuneuro »</TD></TR><TR><TD CLASS="quote"> why exactly does he get banned?</TD></TR></TABLE>
Without delving into much of it, at least once it has been over a bunch of political BS on this site between him and the moderators/sponsors. Not sure about this time...
Without delving into much of it, at least once it has been over a bunch of political BS on this site between him and the moderators/sponsors. Not sure about this time...