Matt98SS

at what point are the stock lifters the limitation in the valve train?

is it related to ramp? or lift? or just plain @.050" duration

what is the best remedy for this if you are pushing the limits? that ARE Rev Kit or a better roller lifter with appropriate pushrods?

thanks

Matt

CHRISPY

That is a good question and I am wondering that myself.
The cam I am going with is
228/228 112LSA .588 lift!!
Not sure what the best choice for lifter would be?
I am going to shift at 6600rpm and probably make peak power around 6400-6500 on the dyno.
Cheers,
Chris

Matt98SS

wish solid roller set up was more affordable but its pretty exotic at this point for most of us

Pro Stock John

iTrader: (34)

I had been told by one place that alot of the folks using stock lifters don't see all of the advertised lift because the stock lifter bleed down.

I am running Comp R lifter and I have yet to prove they were worth the money. <img src="gr_stretch.gif" border="0">

steve

yea but you start getting some loft ground in the cam and really spin that motor jihn and you will see they are worth it.

the stock lifter does bleed down too.

steve frank

Pro Stock John

iTrader: (34)

Matter of fact I had heard of some cams having big lift but the theory behind it was that some of those .570-.590 cams weren't gonna see all that lift from bleeddown.

I'm actually a support of the Comp R lifters, I would not spin a hydraulic motor north of 7000 w/o aftermarket lifters...

John

Matt98SS

so the lifter limitation lies in the RPM and lift and not so much in the ramp.

what do stock eliminator cars use? stock lifters right?

Visceral

iTrader: (1)

no... the ramp of the cam and the spring pressure are what beat on lifters, IMHO. I recently had alot of problems with stock lifters. 1.8 ratio rockers and K-motion K-800s flattened the lifters, and power bailed out around 6100 rpm.

I replaced the rockers with stock, and put in Crane springs that werent nearly as hard as the K800s. Still hard, but not that hard.

By this point I had destroyed a lifter. I replaced the whole set with Comp R. I dont see that much of a difference between the stock and Comp R lifters. They were a replacement for me for a broken/abused stock set.

jmX has a few problems with the Comp R lifters not staying up when you want to pull the cam out. He solved that problem with 16 telescoping magnets, but it is still worth mentioning. Others implied that their CompRs had stayed up just fine.

The only other performace factor that is different appears to be the fact that the stock lifters have about .150-.180 bleed down plunger room. The CompRs, while I have not seen them in a vice, sound like they only have approx .080. Just an FYI for cars that dont have adjustable rockers, cam base circle changes, and people dont always use the right length pushrods or measure preload.

\chris

Pro Stock John

iTrader: (34)

But they might overcompensate for bleeddown by running a ton of lift and/or maybe running a lot of oil pressure to pump the lifters more solid?

LS1derfull

Keep in mind lifter collapse is result of spring pressure not hi lift. You need the right amount of spring pressure, but not too much. Now what is keeping people from adjusting hydraulic factory lifters with say only .010" before plunger is bottomed? I have done this with Gen. 1 small blocks, and that .010" is just enough to allow for heat expansion/contraction of engine components. This way lifter acts like a solid and cant collapse more than .010". As long as this adjustment doesnt block oil flow to pushrod this should work. What do you guys think?

LS1derfull

STEVE, do people really use lofting with roller lifters? Doesnt sound reliable.

steve

some have.
but its for high rpm stuff..as you know

steve frank

LS1derfull

Steve, what do you think of my idea in above post?

Pro Stock John

iTrader: (34)

Visceral, incorrect valvetrain geometry and too much spring pressure can cause lifters to collapse as well. Many folks do not ever measure their lifter preload.

Patrick G

iTrader: (14)

Some of you guys have the lifter preload backwards. Hydraulic lifters bleed down at low rpm, but not high rpm. At high rpm, the lifter will want to pump up and go solid. If you have the pushrod at the bottom of the lifter and the lifter pumps up at high rpm, your valves will never close all the way and you will lose mucho horsepower.

Ideally, you want to have the hydraulic lifter preload as small as possible...meaning the plunger depth should be around .010" (in a perfect world). This way, when the lifter goes solid (at high rpm), you will not be hanging the valve open. Shallow plunger depth...good. Deep plunger depth...bad.

LS1derfull

PatrickG, you are right but your explanation is accurate if loss of valve control at high rpm happens, thats why lifter pumps up because it sees slack from pushrod rocker and valve not staying on cam.The idea i have listed on this page above, would eliminate all rpm, bleed down please reread it and comment on this.

LS1derfull

Patrick G, well what do you think?

Patrick G

iTrader: (14)

In a perfect world (where the hydraulic lifter always has constant pressure from the pushrod even at very high rpm), your theory would work...however, with the typical variety of performance valve springs used on LS1s, I don't think it's possible. Once you exceed 6500 rpms, there is a very natural tendancy for a hydraulic lifter to pump up...mainly because the pressure on the lifter does not remain constant. I'm afraid for your theory to work in practice, you would have to run at least 160 lb spring pressure at the seat and over 400 lbs open to achieve this.

Sounds like we're trying to accomplish the same thing from different methods. My way would rely on the hydraulic lifter going solid from not running enough spring pressure, and yours would be making the lifter go solid by collapsing (in a way) the lifter to make it go solid by running too much spring pressure. Both methods could work...I've just found my way is a very popular way to get increased rpms without resorting to higher spring pressure.