Eric2004

The new novarossi long stroke engine having a stroke of 14.25mm and bore of 13.75mm seem to exceed the displacement of the standard (MR.NR. NSR) 13.8x14.0= 2.1cc
So the new long stroke engine creates more power is because it has bigger displacement?
The MT12 having same piston/sleeve set as the NS version but just with a longer conrod still has the same stroke (14mm)? Or does it have different stroke? Longer conrod seem to just effect the timing but didn't change the stroke value.

Help me please?

EdwardN

iTrader: (1)

This engines you are refering to is still 2.11 cc.
The difference in strok that small, so it is not a reason to be more powerfull. Actualy longer strock-is more torq, but less top RPM ( it is in general).
Longer conrod is changing the angle of pressure to cranckpin, but it also required lift up sleeve and it brings crancase volume higher. So everything has t + or -. Conrod elenght has very little impact on timing. 1 mm longer conrod create less then 1 degree exaust and transfer timing ( please don't get mistaken that use of longer conrod in the same case isn't possible, so in aasumtion that longer conrod-longer case).
Just for insatnce 25 mm conrod, with exhaust height 4.5 mm and strok-154.41 degree. 26 mm conrod 4.5 mm exhaust height, 14 mm strock -is 153.74 degree.
In case what we call long strok engines-timing will have following # strock 14.25 mm, exhaust height 4.5 mm, conrdo lenght 25, so timing on exhaust come up to 153.31 degree. It will required to have little bit shorter pipe to have the same top RPM.
Conrod lenght, strock, timing are different things, even they affect each other.

Eric2004

What is the formula to calculate displacement?

EdwardN

iTrader: (1)

3.14 multiply on squire of piston diameter, devide on 4 and then multiply on strok.

Eric2004

So what is the purpose of having a NS and a MT version of the engine. Since both have same piston and sleeve set. The stroke is still 14mm.
The factor that change the stroke value is the distance between the center of crankpin to the center of the crakshaft, which equals 1/2 stroke. So a 14mm stroke will have the center of crankpin to center of crankshaft of 7mm. one complete revolution will move the conrod up and down 14mm. Am I right.

So in order for the new long stroke engine to have longer stroke, the distance bw crankpin center to crankshaft center must be change although the conrod may remain the same length!!

EdwardN

iTrader: (1)

yes in order to have longer strok-needs to move pin out on 0.125 mm of center why it was done, realy good question!!!!
it doesn't change tramendosly anything, that changes which happened are nothing.
strok and conrod length is changing conrod ratio, it is very important value, but again, on tht particular engine it is so small, so it will not change anything. I was thinking about it, for while and it come to my calculation, that only one thing can be realy impacted vacuum value on induction cycle, but again, I didn't find to much difference ( but it was greatest change on that design)

Eric2004

So do you think there is a real significant difference in terms of power output between the old and new engine? Or was the effect only placebo ( you know, nova produce a new engine, people think it is "new" and must be more powerful, so when they run it, they think it is more powerful where in fact it is the same. or the difference is insignificant.)

By the way what is the conrod length and stroke ratio? Haven't heard of it? How does it effect the performance?

Phatkat

iTrader: (14)

It's actually bore x stroke.

EdwardN

iTrader: (1)

We start mesure displasment in squire not in cubic?
So it is come up to 13.76x14.00=1.926 sq. cantimeters-is this our displacment? So, we are undersized ( It is allowed to use 2.11 cubic cantimeter).
GO BACK TO SCHOOL!!!!!!!!!!!!!!!
LEARN THE DIFFERENCE between squire and cubic!!!!!!!!!!!!

EdwardN

iTrader: (1)

I am sure it is placebo ( first time hear this word).
This value is also called conrod ratio. It is very important number and it was banch of theories about it, but so far good number is between 1.78 to 1.83. it is actualy related very close to power band and depend of aplication is changing. Bigger # move power band to torq side, smaller # move power band to RPM side ( it is simple answer, actualy it is much more complecated and realy don't want to go further and will not).
Our engines aren't that easy and realy complecated ones you start design something. I wasn't do any calcuations for more then 10 years, till now. And now luckely all my old notes are with me.

teammpp

In technical terms there is no conrod length to stroke ratio. Basically, providing you are within the 2.11cc anything can go.

As was already mentioned a longer stroke will produce more torque because the rod moves up and down at a slower pace over a fixed rotation due to having to rotate a larger distance.
With short stroke the vertical movement is much faster on the same given rotational speed as it doesnt have as far to travel to complete a full circle.
The myth of the long and short stroke engine is mainly hype. All the current engines on the market are longstroke because the stroke is greater figure than the diameter of the bore. An engine only becomes short stroke once the stroke length becomes smaller than the diameter of the bore. When both are equal we usually call this a box engine.

Now, rod length is a different issue. A shorter rod means there is a more acute angle of the conrod in relation to the piston at TDC and BDC. This places excess wear on all the moving components as the conrod at first is wanting to push the piston through the side of the sleeve and then pull it back through the same side on the way down. Making the rod longer decreases the acuteness of the angle and helps the engine work less effortlessly.

The problem here is that everyone is continually striving for lower CG's in the car to better the performance. One of the biggest gains is in the engine. Make the engine as low as possible and you vastly reduce the CG. At the same time you make the sacrifice of rod length and longetivity of the engine.

Eric2004

Very good point, thank you.
So everyone watch, don't get caught with Novarossi's trick in marketing.

Phatkat

iTrader: (14)

Where'd you learn to spell? That stuff is a headache to read. And I need to go back to school? Whatever.

EdwardN

iTrader: (1)

Yo homez u stay in ur crib i stay in mine.
Is this better?

Phatkat

iTrader: (14)

Uh, I guess......