Lifter Collapse and Boost Levels

**shownomercy** · 06-29-2015, 12:47 PM

Lets say lifters were getting the crap kicked out of em, and were collapsing *, then, new fancy lifters were installed... nothing changed in tune, but, 5psi more now.

Logical theory?

*removed under boost for clarity*

***SSlowBoat*** · 06-29-2015, 12:57 PM

Originally Posted by shownomercy

Lets say lifters were getting the crap kicked out of em, and were collapsing under boost, then, new fancy lifters were installed... nothing changed in tune, but, 5psi more now.

Logical theory?

Same valve springs? Seems legit

**blackbirdws6** · 06-29-2015, 12:59 PM

Why would a lifter collapse under boost? Boost would help the valves open which is why you run higher spring pressure. I'm sure in general with the new lifters you have better valve control which may have attritbuted to things leaking prior.

**shownomercy** · 06-29-2015, 02:09 PM

Originally Posted by blackbirdws6

Why would a lifter collapse under boost? Boost would help the valves open which is why you run higher spring pressure. I'm sure in general with the new lifters you have better valve control which may have attritbuted to things leaking prior.

I edited my original post, more boost would mean less spring pressure AFAIK.

**blackbirdws6** · 06-29-2015, 02:13 PM

Originally Posted by shownomercy

I edited my original post, more boost would mean less spring pressure AFAIK.

You need more spring pressure with more boost to help keep the valves closed.

**shownomercy** · 06-30-2015, 12:16 PM

Should I title it "why my LT1 is puttering and running crappy, is it the opti???"

Meh.

**firebird_1995** · 06-30-2015, 04:29 PM

So is it still running bad? As far as picking up additional boost, you can't rule out the fact you changed the intake gaskets (could have been leaking) and adjusted the rockers (could have been too tight)

**BIG CAT** · 06-30-2015, 06:16 PM

boost is volume with no where to go. if you picked up 5 psi i would have guess your new lifters are lighter(lessening valve float) than the old ones or the old ones were pumping up and holding the valves slightly open. i run a rev kit with mine set at basically zero lash so even if they pump up it will not hang a valve open.

**joelster** · 06-30-2015, 08:26 PM

Or the old ones were adjusted improperly. They might have had too much preload on them and they were pumping up causing a valve or valves to stick open.

**gmpowered** · 07-01-2015, 12:21 PM

Originally Posted by joelster

Or the old ones were adjusted improperly. They might have had too much preload on them and they were pumping up causing a valve or valves to stick open.

Yuppers, having rockers too tight will collapse lifters, and bleed cyl pressure.