What is the difference and pro's and con's of short travel lifter's and ls7 lifter's for drag racing?

 

LS7 lifters ARE std. travel lifters

 

Short travel lifters are designed with less lifter plunger (piston) travel which results in less oil volume under the plunger. This is beneficial because the more oil under the lifter plunger the more chance for that oil to become aerated.
Aerated oil can compress and lead to loss of valve lift.

Circle track/dirt track racers became aware of this at some point and as a way to cheat the strict rules of classes that required hydraulic lifters they would add spacers under the lifter plunger to create a short travel lifter. This was before short travel lifters existed.

Short travel lifters can be noisy and hard on valvetrain parts if they bottom out. They are more prone to bottom out since they have less oil under the plunger.

The regular travel lifters and LS7 lifters have enough travel to almost completely compress (allow the cam lobe to come to the top) before they bottom out, which under normal operation will never happen. But since they have over .200 travel that leaves a lot of oil under the plunger to potentially become aerated and reduce valve lift under certain conditions.

One thing a lot of people don't realize is that you don't have to stick exactly to the recommended lifter preload with standard or LS7 lifters. The total plunger travel can be measured and you can make these a short travel lifter in a sense. The only problem with this is they aren't designed to bottom out like the short travel lifters are.

As an example you can measure a regular lifter and say you get .200 plunger travel from zero preload to fully compressed. Most preload recommendations I've seen are around .080.
At .080 preload you have .120 space under the lifter plunger for oil, this is a lot more than a short travel lifter. So what can be done is run a longer pushrod so you have .150 preload and .050 space under the plunger. This reduced amount of oil volume is much less prone to getting aerated and reducing lift. One exception might be a cheap lifter that can't hold the hydraulic pressure, these could bleed down, bottom out, and cause noise and lifter damage since they aren't designed to run bottomed out like a short travel lifter.

The short travel lifter is close to a solid lifter with 'some' oil to cushion the lash.

 

Hmmmmm

 

https://www.enginelabs.com/news/vide...on-horsepower/

An article I bookmarked quite some time ago. I don’t recall it getting much discussion. But it says what Black just posted.