What would you guys do with the clearances in a motor that must last 50k+ miles, but goes from the 90.7mm stroke of an H22 to 97mm stroke of an F23? Mainly concerned about the rod bearings.

Normally for longevity, one would use tighter clearances. But the load on the bearings increases significantly when stroke increases this much. To counter that, looser clearances, but that's detrimental to longevity.

Main complications are the facts that:

-H22 oem clearances were designed for not nearly as much stroke. They were designed for load created by 90.7mm at 7500rpm, not 97mm at 7500.

-F23 oem clearances were designed for narrower journals, a lot less power and 1k rpm less redline

So what do you do?

 

In to learn something. Can't really contribute anything.

With my setup we took a few precautions to ensure the rotating assembly would be as balanced as possible to avoid harmonic vibrations that might risk a rod bearing failure.

 

.017 ON THE MAINS
.020 ON #3

.016-018 ON THE RODS.
balance and clean up the crank girdle.
on oem rods you should be good to 8500 if you make power their

 

run alittle tighter on the mains say.017 on 1,2,4,5
.019 on #3 if your revving to 7500rpms
you could also go .015-.017 on the rods also.
many options will work. have fun

 

what experience have you had with this to provide the information you have given?

 

Oil viscosity should also play a factor IMO...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PyroProblem &raquo;</TD></TR><TR><TD CLASS="quote">Oil viscosity should also play a factor IMO...</TD></TR></TABLE>

Absolutely! But to what extent and how do you spec the two together?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PyroProblem &raquo;</TD></TR><TR><TD CLASS="quote">Oil viscosity should also play a factor IMO...</TD></TR></TABLE>

not really. set your bearing clearances up to make the engine last, block the oil squirters, use a good oil pump, and change the oil weight to get your pressures where you want it.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vinuneuro &raquo;</TD></TR><TR><TD CLASS="quote">What would you guys do with the clearances in a motor that must last 50k+ miles, but goes from the 90.7mm stroke of an H22 to 97mm stroke of an F23? Mainly concerned about the rod bearings.

Normally for longevity, one would use tighter clearances. But the load on the bearings increases significantly when stroke increases this much. To counter that, looser clearances, but that's detrimental to longevity.

Main complications are the facts that:

-H22 oem clearances were designed for not nearly as much stroke. They were designed for load created by 90.7mm at 7500rpm, not 97mm at 7500.

-F23 oem clearances were designed for narrower journals, a lot less power and 1k rpm less redline

So what do you do?</TD></TR></TABLE>


i take it you are using the f23 rods also,so that right there will tell
you what to set your clearances at for longevity.the r/s is i think 1.45
so your rev. limit stock is 65-6800.YOU COULD OFF SET THE PISTON
this would help,but then you start running into money w/custom parts.


the stock motor lasts 100k+ w/some pretty tight clearances.but that
r/s is your KILLER.

harv

 

just compare the h22a clearance specs to the f23a specs and go from there with your oil weight choice...thats pretty much all you can do see what will work i know they both share super similar main journal oil specs...

im in the same situation except im going to a 90.7mm from 97mm with this g23 vtec...both specs are damn close though minus the rods

i need some insight on this as well keep this thread going

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 98vtec &raquo;</TD></TR><TR><TD CLASS="quote">what experience have you had with this to provide the information you have given?</TD></TR></TABLE>

enough to give some advise. their is nothing wrong with going tight or even .015 all around but when you do a swap like this, odds are the damn thing is going to driven hard. if it wasn't then the hp and rpms from a stock h22 would have been more than adequate.
i would run 30w first and then go from their.
but other setup will work without problems

 

also the 55mm mains alow for less crank flex and less distortion on the rod journals. teamed with the bearings this allows for less needed width.
i would worry more about oil flow seeing that this is a bottom feed setup.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by I smell secretions &raquo;</TD></TR><TR><TD CLASS="quote">also the 55mm mains alow for less crank flex and less distortion on the rod journals. teamed with the bearings this allows for less needed width.
i would worry more about oil flow seeing that this is a bottom feed setup.
</TD></TR></TABLE>
&lt;3 secretions

 

here is another thing that i'll take to my grave with me believing.
h22's are notorious for #3 rod spinning on the 50mm cranks.it really
sounds like to me the crank is bowing "v shape" in the middle causing
the #3 rod journal to distort and premature wear that bearing out.
im not saying this is solid proof "JUST WHAT I BELIEVE IS HAPPENING"