Min assembly weight effect on ET
 

If you were able to lose 100 grams off your rod/piston weight. How much ET difference would you see? I’ve looked all over trying to find an answer with no luck.

Re: Min assembly weight effect on ET
 

Zero.

Re: Min assembly weight effect on ET
 

100 grams * 8 = 800 grams / 1.7637 lbs

Let say that weight is at a 4" radius with an acceleration rate of 2500 RPS.

Stan

Re: Min assembly weight effect on ET
 

It sure won’t hurt …l

Re: Min assembly weight effect on ET
 

That depends on where and how much weight was removed. Is the part now no longer as strong as it needs to be, and it is flexing which will cost you more HP than the weight saving gave you?

Stan

Re: Min assembly weight effect on ET
 

I have to disagree Stan. I believe the OP is referring to his LT 1 stocker and he is blueprinting the piston/rod combo to achieve the minimum weight spec set by NHRA. I dont believe he is in any danger of weakening or flexing any stocker parts…

Re: Min assembly weight effect on ET
 

The bulk of the weight reduction would come from a lighter rod. Production GM rod that has had small end bushed and ARP rod bolts installed vs significantly lighter Manley Rod thats on the approved list.

Re: Min assembly weight effect on ET
 

Then you should be fine. I took it as you were going to lighten the parts you had.


Stan

Re: Min assembly weight effect on ET
 

On our small block Mopars less than a hundred.

Re: Min assembly weight effect on ET
 

I was hoping for a better outcome. Im about 120 grams per assembly heavy. Thats basically running a ninth piston assembly

Re: Min assembly weight effect on ET
 

I dont know about horse power but it should help the engine accelerate quicker.

Re: Min assembly weight effect on ET
 

When I produced that graph I just used the weight stated and picked a distance from the center line and an acceleration rate.

How much does that weight change reduce the needed bob weight, or it other words how weight can be removed from the crank also?

Stan

Re: Min assembly weight effect on ET
 

When we were looking at this back when piston rod assembly weights were enacted the thought was to remove as much weight as possible from reciprocating components and bring it toward the center rotating mass. This would be just one place to work.

Re: Min assembly weight effect on ET
 

With that in mind. Remember when looking at rod weights that only the small end weight is reciprocating and big end weight is rotational.

Stan

Re: Min assembly weight effect on ET
 

Depends
Rotating weight IE: crankshaft Counter weight and rod big end act like flywheel weight.
Reciprocating IE: upper rod, piston and pin and rings are a start & stop motion and absorb energy in the start and stop.
100 G off each upper reciprocating only lightens the crankshaft counter weights 100 G.
100 G. off the big end of each rod lightens each rod journal 200 G. (2 rods per journal) The end crankshaft counter weight is lightened a corresponding amount. The total effective loss of rotating is 400 G.

Re: Min assembly weight effect on ET
 

The thought was that reducing weight close to the center of rotation does not produce gains as would further out from center.

When thinking about flywheel weigh with large and small diameter which has more effect? On old machines have seen had large flywheels which stored energy better than smaller diameter. Those things driven by leather belts were effing dangerous started slow and slow to stop.