Exhaust pipe builders dream - calculator

[neil_cb125t]

I found one of these tuning gurus from UK who has sadly passed away. Apparantly he specalised in twins and the like but the page has allot of cool links and calcs like compression and squish etc.

The link for his site is here: http://mez.co.uk/mezporting/ but the exhuast calculator is found here http://www.mez.co.uk/mezporting/exhaust_length.html

All you need to do is input the Exaust cam timing and your ideal max RPM your away. If only we had found it before we built the ER pipe.:facepalm:

[imdying]

In case it disappears in the future:



var mydeg;//Enter as test 74 deg open
var myexdur;//enter exhaust close 36
var myrpm;//6500 rpm
var mycc; //324 cc
function howlong(form) {
a = (mydeg +180);
b = Math.round((850*a)/(myrpm)-3); //length length of priamary pipe
c = Math.sqrt((mycc /((b+3)*25))); //inside diameter of priamary pipe
c = (c *2.1);
c = Math.round(c*1000)/1000;
d = ((228*a)/(myrpm-500));//induction length of carburator
d = Math.round(d*1000)/1000;
e = Math.sqrt((c *c)*2)*.93;//two secondary pipe inside diameter
e = Math.round(e*1000)/1000;
f = 15; // fours primary length always 15 inch
h = b-f; //length of secondary pipe
g = Math.sqrt((mycc *2)/((b+3)*25))*2; //tailpipe inside diameter
g = Math.round(g*1000)/1000;
j = (((c*2)-g)/2)*12.115; //collector length was 7.115
j = Math.round(j*1000)/1000;
k = (b+3.4)-j;
l = (myexdur+a)
m = l; // Ehaust Duration
n = (l /2) -myexdur ; //valve corecttly timed
p = (myexdur *2); //overlap



form.overlap.value =p; //overlap
form.fulllift.value =n; //valve corecttly timed
form.duration.value =m; // Exhaust valve duration in Degrees.
form.ind.value = d; //Carburetor induction Length in Inches .
form.length.value = b; //1, Tuned length From the Valve Head.
form.outside.value = c; //2, Primary inside Diameter is in Inches
form.secondary.value = h; //3, Secondary Pipe Length in Inches .
form.inside.value = e; //4, Two Secondary pipe inside diameter. .
form.primary.value = f; //5, Fours Primary Pipe Always (15" Inch)Long.
form.collector.value = j; //6, Collector box Length in Inches.
form.tailpipe.value = g; //7, Tailpipe inside in Inches.
form.taillength.value = k; //8, Tailpipe Length in Inches.

}

function Fmyover (lap){
myover = parseFloat(lap.value); //overlap
}
function Fmydeg(degrees) {
mydeg = parseFloat(degrees.value);
}
function Fmyrpm(myrevs) {
myrpm = parseFloat(myrevs.value);
}
function Fmycc(myceecee) {
mycc = parseFloat(myceecee.value);
}
function Fmyexdur(dur){
myexdur = parseFloat(dur.value);
}
function Fmyind(induct) {
ind = parseFloat(induct.value);
}
function Fmyinside(twoo) {
inside = parseFloat(twoo.value);
}
function Fmyprimary(prima){
primary = parseFloat(prima.value);
}
function Fmytailpipe(tail){
tailpipe = parseFloat(tail.value);
}
function Fmysecondary(sec){
secondary = parseFloat(sec.value);
}
function Fmycollector(coll){
collector = parseFloat(coll.value);
}
function Fmytaillength(tail){
taillength = parseFloat(tail.value);
}
function Fmyfulllift(lift){
fulllift = parseFloat(lift.value); //valve corecttly timed
}

function clearit(form){
form.mydeg.value = "";
form.myrpm.value = "";
form.mycc.value = "";
form.myexdur.value = "";
form.duration.value = "";
form.length.value = "";
form.outside.value = "";
form.ind.value = "";
form.inside.value ="";
form.primary.value ="";
form.tailpipe.value ="";
form.secondary.value = "";
form.collector.value ="";
form.taillength.value ="";
form.fulllift.value =""; //valve corecttly timed
form.overlap.value = ""; //overlap
}