Sorry if this is a repost but what is the best rod/stroke ratio in your opinion. Also what is the Equation to find the ratio?

thanks
mike

 

in my opinion it is not about the rod/stroke ratio but how well the engine is balanced before it is put together. a b20 can rev to 11k if the top end has the right components to allow it. the bottomend just has to be built to work like a sewing machine, an almost perfect balance a perfect sizing combo. then the bottomend is fluid and the ret is whp

 

There definitely is no "best" ratio.

-Dynamically speaking, when considering the load generated by differing r/s ratios within the engine, the higher the better would be the rule.

-Packaging wise it depends completely on how tall the engine's deck height can be relative to a given stroke while still fitting in the engine bay.

-Performance wise higher ratios will show more linear torque output over large RPM ranges, but this is just slightly so and still much more strongly influenced by everything else on the top end of the motor than r/s ratio.

-Tuning wise the only thing that is at all strongly affected by r/s ratio is the nuances of cam timing, but this can be optimized easily enough for any r/s ratio.


In other words, it's a compromise of many factors and different engines with vastly different r/s ratios can both perform very well in a variety of circumstances. As I've always said, r/s ratio is about the last thing your average performance junkie should be concerned about, as there is little one can do to significantly alter it anyway.

Ps- You calculate r/s ratio by dividing the connecting rod's center to center length by the crankshaft's stroke.

 

1.75 R/S

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by indomotor &raquo;</TD></TR><TR><TD CLASS="quote">1.75 R/S</TD></TR></TABLE>

Care to explain?

 

I figured if the bottem end was balanced and was built properly the engine would prrrrrrr. One other question... have you guys with balanced bottem ends noticed the diff. ? does the engine sound different?

thanks
mike

 

does anyone know where i can find a complete list of all honda motors for thier R/S ratio?

B16a
B18b
B17
B18c
B18c5
B20
LS
H22
F22
F23
D16a6
D16z6/y8
ZC
--
H23
D15

I'd really like some numbers so that i can just kinda referrance and compare off of. thanks guys

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by infamousLSVTEC &raquo;</TD></TR><TR><TD CLASS="quote">Sorry if this is a repost but what is the best rod/stroke ratio in your opinion. Also what is the Equation to find the ratio?

thanks
mike</TD></TR></TABLE>

The best rod stroke ratio is the one that makes the best use of the cylinder head
for a given displacement. 1.75 is not always the magic number as some would
like to believe.

 

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

The best rod stroke ratio is the one that makes the best use of the cylinder head
for a given displacement. 1.75 is not always the magic number as some would
like to believe.</TD></TR></TABLE>

Exactly...

1.75:1 is generally accepted as the best 'compromise' . I would never take a higher R\S Ratio over more Displacement tho, unless we are talkin extremes.

1.58:1 1.8L &gt; 1.75:1 1.6L

1.54:1 2.0L &gt; 1.58:1 1.8L

1.58:1 2.2L &gt; *

Suprdave

 

The equation is:
Rod Lenth (C to C) divided by the Stroke = R/S Ratio.

Dart B20 Tall Block + LS/B20/Eagle 89mm crank = 2.0L + 1.69 r/s ratio.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Charlie Moua &raquo;</TD></TR><TR><TD CLASS="quote">does anyone know where i can find a complete list of all honda motors for thier R/S ratio?</TD></TR></TABLE>
I found this awhile back, but I cant remember where.
<u>ENGINE HP SIZE DECK BORE STRK ROD C-H PIN H-D BEW BEB R/S VA VS D-S V-N MODEL</u>
B18C1 170 1797 8.347 3.189 3.433 5.429 1.181 21 41.6 .858 48 1.58 26 33/28 D-V 94-97 GSR
B18C5 195 8.347 3.189 3.433 5.429 1.195 21 42.7 .858 48 1.58 27 33/28 97-98 TYPE-R
B18A1 130 1834 8.347 3.189 3.504 5.394 1.181 21 48 .935 48 1.54 25 31/28 D-N 90-93 INTEGRA
B18B1 140 AS ABOVE 94-97
B17A1 160 1678 7.998 3.189 3.205 5.208 1.181 21 42.7 .935 48 1.62 27 33/28 D-V 92-93 INTEGRA
B16A3 160 1595 7.998 3.189 3.047 5.290 1.181 21 42.7 .935 48 1.74 27 33/28 D-V 93-97 DEL-SOL
B16A1-A2 AS ABOVE J.D.M
H22A1 190 2200 8.655 3.425 3.571 5.630 1.222 22 53.8 .935 51 1.58 29 35/30 D-V 92-97 PRELUDE
H23A1 160 2300 8.655 3.425 3.740 5.571 1.203 22 50 .935 51 1.49 25 34/29 D-N 92-96 PRELUDE
H23A4 195 AS ABOVE 97-98
D16Y8 127 1590 8.347 2.953 3.543 5.394 1.154 19 32.8 .892 48 1.52 30/26 S-V 96-99 CIVIC
D16Y7 106 1590 8.347 2.953 3.543 5.394 1.181 19 34.6 .892 48 1.52 30/26 S-N 96-99 VARIOUS
D16Z6 125 AS ABOVE 30/26 S-V 92-95 CIVIC
B20B4 1973 8.347 3.307 3.504 5.394 1.181 21 45 .935 48 1.54 25 31/28 S-N 97-UP CRV
D16A6 8.347 2.9

ENGINE = engine code
HP = factory horsepower rating
SIZE = engine size in c.c. cubic centimeters
BOR = standard engine bore in inches
STRK = engine stroke in inches
ROD = engine rod length center to center in inches
C-H = compression height of piston in inches
PIN = wrist pin outside diameter in millimeters
H-D = cylinder head volume in c.c. cubic centimeters
BEW = connecting rod big end width in inches
BEB = connecting rod big end housing bore diameter
D = double overhead cam
S = single overhead cam
N = non v-tec
V = v-tec 1 millimeter = .03937 inches
DECK= deck height in inches
R/S= rod to stroke ratio
VA= valve angles in degrees
VS= valve sizes intake/exhaust diameter in millimeters
53 3.543 5.394 1.161 38

 

haha thanks bro

 

thanks JEFF C that is a great piece of info...

 

No prob. I have not checked it or anything so I am not sure of its accuracy. It will probably be earier to copy and paste it into Excel and put the info in a chart format.

 

There actually IS a best rod ratio. And that is an INFINITE rod ratio. But since such a rod ratio is not practical, all I can say is that the higher, the better.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by StorminMatt &raquo;</TD></TR><TR><TD CLASS="quote">There actually IS a best rod ratio. And that is an INFINITE rod ratio. But since such a rod ratio is not practical, all I can say is that the higher, the better.</TD></TR></TABLE>
all i can say is...

 

I'd take an infinite rod ratio if it was practical...