Does anyone know where one is at on the web w/ pre-entered fields such as c-speedracing's compression calculator?

is there a "perfect" rod/stroke ratio?

 

No and No.

Unless you feel like spending hundreds of dollars to get a VERY slight improvement on rev speed, don't bother worrying about the R/S ratio.

 

okay...settles that then.

 

Well.. the biggest challenge is getting the actual numbers, not performing simple division! However, 10 minutes with a good search engine will find you all the data you need for rod lengths and stroke unless you have a very strange engine.

Here's one source that has brought a lot of the information together:

http://www.hstuners.com/news/wmview.php?ArtID=6

As far as 'perfect', one group says 1.74... while others say you can throw it out the window. Truth is.. probably somewhere in between. I don't think it is that simple, but R/S could be a factor. Most people bulding the B's aren't going for 200k miles between oil changes, so longevity may not be the biggest factor. That's one area where a poor (1.4x or less) R/S might cost you downline. Especially if you wind it up a lot (RPM).

There is an article here: http://www.theoldone.com/articles/badtothebone/ where Larry builds a B20 (89mm stroke), and uses rods which are .137" longer than stock (stock is 137mm). The conversion from inches to metric (2.54mm / inch) is 3.4798 (conversion calculator is here http://www.twcac.org/Tutorials/dista...calculator.htm).

So, 137 + 3.4798 = 140.4798mm Rod length, and the stroke is 89mm, so...

140.4798 / 89 = 1.578 R/S

And *he* plans to rev the thing between 9400 and 10,000 RPM! Not bad for a B20...

Have fun.

Mark

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by msilbernagel &raquo;</TD></TR><TR><TD CLASS="quote">
Well.. the biggest challenge is getting the actual numbers, not performing simple division! However, 10 minutes with a good search engine will find you all the data you need for rod lengths and stroke unless you have a very strange engine.

Here's one source that has brought a lot of the information together:

http://www.hstuners.com/news/wmview.php?ArtID=6

As far as 'perfect', one group says 1.74... while others say you can throw it out the window. Truth is.. probably somewhere in between. I don't think it is that simple, but R/S could be a factor. Most people bulding the B's aren't going for 200k miles between oil changes, so longevity may not be the biggest factor. That's one area where a poor (1.4x or less) R/S might cost you downline. Especially if you wind it up a lot (RPM).

There is an article here: http://www.theoldone.com/articles/badtothebone/ where Larry builds a B20 (89mm stroke), and uses rods which are .137" longer than stock (stock is 137mm). The conversion from inches to metric (2.54mm / inch) is 3.4798 (conversion calculator is here http://www.twcac.org/Tutorials/dista...calculator.htm).

So, 137 + 3.4798 = 140.4798mm Rod length, and the stroke is 89mm, so...

140.4798 / 89 = 1.578 R/S

And *he* plans to rev the thing between 9400 and 10,000 RPM! Not bad for a B20...

Have fun.

Mark</TD></TR></TABLE>


WOW

I just read that whole article. That thing is going to be a beast. Imagine if, or should I say when, these guys get a hold of a K24 for a project motor.

 

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

Unless you feel like spending hundreds of dollars to get a VERY slight improvement on rev speed, don't bother worrying about the R/S ratio.
</TD></TR></TABLE>
yes, there is a perfect rod/stroke ratio, it is 1.75:1, and the guys who think 1.74:1 is perfect are b16a builders. most engine builders say anything between 1.7-1.8:1 is acceptable. anything less will cause unwanted sidewall loading, creating more friction and a loss of power. anything more will cause a narrower torque curve.

i am blueprinting a b16 for increased stroke, longer rods, smaller c/d for a boosted application where i will still retain a near 1.74:1 rod/stroke ratio. the stroke will be increased 1.6mm, rod length will be stretched to 137mm and piston c/d will be reduced to 25mm, running a 2 ring setup. im also sleeving the block for an 85mm bore, with Endyn Soft Head pistons that will be able to handle 10psi with 10.8:1 static compression. this is going to be my K-Killer engine.

article found on this site, detailing larrys (the old one) buildup of a d16;
https://honda-tech.com/zero...age=1
not what he did to the bottom end of the d16, and why.

another article by t.o.o.;
http://theoldone.com/archive/motor-geometry.htm

browse around the archives at http://theoldone.com/ to learn even more.