I'm having a little trouble understanding the differences between a couple things.

I picked up an unassembled built h23vtec setup from someone on my florida lude forum. Here are the specs of what i have right now:

h23 block with Darton Liners, 89mm bore.
- bored and honed to piston spec / decked
wiseco coated pistons with 1.218 compression height, Dome cc = 6.00
Custom crower rods with rod lengths center to center of 140.38mm (5.527 inches)
- stock h23 rods are 5.572 inches

the crank i want to run is the 95mm h23.

With this setup, my compression will be around 11.5:1 and my r/s ratio is about 1.48

Missing Gears told me that his was a horrible r/s stroke ratio for daily driving and that i should run an h22 rod with a different compression height piston.

so....i went back to the calculator and entered the specs of the h22 rods (5.633) with pistons of 1.122 compression height and it netted 11.75:1 compression and 1.51 r/s.

Is .03 bump in r/s really going to determine the life of my motor that much?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 98vtec &raquo;</TD></TR><TR><TD CLASS="quote">

Is .03 bump in r/s really going to determine the life of my motor that much?</TD></TR></TABLE>

No.

I know youve read alot on these forums and you already know that r/s ratio determines max piston accel. and sidewall loading. Once you have tossed some decent pistons and rods into the equation, (providing quality install) the numbers dont mean as much.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Combustion Contraption &raquo;</TD></TR><TR><TD CLASS="quote">No.

I know youve read alot on these forums and you already know that r/s ratio determines max piston accel. and sidewall loading. Once you have tossed some decent pistons and rods into the equation, (providing quality install) the numbers dont mean as much. </TD></TR></TABLE>

thanks for the reply steve. Yes i have been reading alot on this stuff. I never really intended to use an h23 block as my platform but this deal was just too good to be true and i had to pick it up and i would like to get it working correctly and safely without having to send the block back out to get spec'd to another set of pistons.

I've got a friend of mine (mmuller) that is going to be assisting me while i assemble the motor. He knows his stuff and i know he wouldnt let me do anything "stupid."

From what i have read, this combo will net a greater acceleration of the piston while traveling away from TDC. Also there is a shorter dwell time over TDC which would keep me safe from hot spots...etc.

With the cams (JUN III) and compression of this motor, it should see power to atleast 8k (being easy) and i want to make sure that i'm not going to be grenading my motor without knowing it.

I have intentions to get rotating assembly balanced so i think that should alleviate some of my worries.

 

I like short rod motors over long rod stuff in every high-perf. street Honda just because most of us will put about 40-50k on our setups before a rebuild, this is usually before the bores start to become excessively (key word excessively) egg shaped.

Short rod motors USUALLY benefit a bit more from well ported heads than their long rod counterparts due to the more acute pressure drop at the onset of the intake stroke. You can also run a tad more compression on them for this same fact.

The long rod stuff usually shines with low piston speed combo's. I am becoming very generic now and will end my post here.

 

well, the head is going to eventually get sent to belben (key word eventually, LOL). and yea, i understand the egg shaping, mostly by the thrust of the piston into the thinner cylinder wall correct? My plan is to have a beater by the time this motor is done so i dont have to put so many miles on it. But then again, my stock H only has like 50k on it so if anything happened, i would always have a reliable backup motor.

appreciate the help steve. Doing my best trying to learn this stuff

 

Sending your head to Belben is a good first move. I havent heard any flow number directly or inderectly from him, but his attitude/demeanor on this forum and others speaks volumes about him.


Plus the pics of his work arent too shabby either.

Youre absolutely correct on the reasoning behind the egg shaping of the cylinder walls. But theres more to that than just R/S ratio. Component weight, amount of TQ factor in to that as well. If you have two 2 liter engines with 1.5:1 r/s ratios , one produces 150 ft/lb of tq with a 300 gram piston, and the other 400ft/lb with a 600 gram piston, which one do you think will start eating oil and leaking compression first?

 

i'd take bets on the latter being that its twice as heavy and the thrust against the walls is more than doubled that of the lighter piston undergoing less work.

Belben sold me just by reading about his history and his outlook on life.

I just got off the phone with Randy as well. He assured me that i would be fine with this r/s ratio ("r/s ratio doesnt mean ****" - randy LOL) and that if anyone tried to tell me i would grenade the motor by revving it, just simply doesnt know anything, lol.

Theres not too many people on these forums that i trust with this kind of information so i was glad that you were one who helped me with my misconceptions.

 

good call now get to it!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Rosko &raquo;</TD></TR><TR><TD CLASS="quote">good call now get to it!</TD></TR></TABLE>

might want to grab some popcorn, prolly be awhile

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Combustion Contraption &raquo;</TD></TR><TR><TD CLASS="quote">I like short rod motors over long rod stuff in every high-perf. street Honda just because most of us will put about 40-50k on our setups before a rebuild, this is usually before the bores start to become excessively (key word excessively) egg shaped.

Short rod motors USUALLY benefit a bit more from well ported heads than their long rod counterparts due to the more acute pressure drop at the onset of the intake stroke. You can also run a tad more compression on them for this same fact.

The long rod stuff usually shines with low piston speed combo's. I am becoming very generic now and will end my post here.</TD></TR></TABLE>

I cant figure out when the term long rod and short rod become applicable. Are these terms simply used for comparisons sake? So with the comparison of H22 vs H23 crank and rods "long rod" ie stock crank and rods from an h22's r/s ratio = 1.58 vs "short rod" ie stock crank and rods from an H23's r/s ratio = 1.49. Is that correct or am i missing something?

 

long rod and short rod in their relation to the crankshaft stroke.