blower compression hight (1 Viewer)

[Mooseman]

I was just reading an article on the setback blower , and about how before the setback blower they would run different rod lengths on the front cylinders and the middle and back . And how they did it to even out compression and allow them to run fuel nozzles of equal sizes . Now this is a silly question but do you have to run different sized rods in a blown carburatered engine? Oh and does anyone have any pics or info on larry meyers shoe device that he invented ?

 

[Mooseman]

Anyone know?

 

[Just Paul]

The reason they came up with the set back blower, is becasue they realized that the blower pushes out a lot more air at the front of the blower, then in the back. They now put the front of the blower over the center of the motor to try and even things out a little better.

To answer your question though, I guess it depends on the application and what kind of blower it is. It's probably not worth the hastle.

 

[Nitrohaulic]

They also use a plate with a small opening to control where the compressed air and fuel enter the manifold. Before the set back blowers they experimented with things in the manifold (think some were called "shoes") to keep too much air from going into the front cylinders.

 

[Big Sexy]

Some teams might have used rods to change Compression Height, and others just changed pistons. I know I ran some 110 out on 1 and 2, 130 out on 3 and 4 and 150 on 5,6,7 and 8. Kept the rods the same.

The shoe is another way of accomplishing the same thing as the setback.

Justin

 

[TF CREW]

Some teams might have used rods to change Compression Height, and others just changed pistons. I know I ran some 110 out on 1 and 2, 130 out on 3 and 4 and 150 on 5,6,7 and 8. Kept the rods the same.

The shoe is another way of accomplishing the same thing as the setback.

Justin

basiclly #1 & #2 rods are .020 shorter than the rest

 

[.]

If you ever get the chance to chat with Norm Drazy of PSI be sure to take advantage of the oppurtunity! I chatted with him for a while at Seattle in 2004 and it was the most interesting and informative chat I've ever had with anybody about superchargers and fuel/air flow. You'll come away with a whole new appreciation for waht these engines are doing and how they're tuned.

 

[Tom]

What about back driving( reversing) the rotors? Will a blower put out as much air? This would put the air where it needs to be without blower set back. Has anyone tried this?

 

[Big Sexy]

basiclly #1 & #2 rods are .020 shorter than the rest

Left the rods all 7.003". Just have different Compression Height on the pistons. So much easier than mixing up different sets of rods.