LS Hydraulic lifter limitations
 

I am running the GM perf LS7 hydraulic lifters in my stocker. It hits a wall in high gear at 7K which occurs between 1000ft and the finish line. Just stops pulling and sometimes has 2-3 light misfires ( banging) . I know the lifters should easily handle 7K ..but is that the limitation? I am running 10-30 oil so staying pumped shouldn't be a problem. I am going to do compression,leak down test and valve spring test as part of off season maintenance. Should I just go ahead and change to solid lifters?... Thanks!

Re: LS Hydraulic lifter limitations
 

I can't speak for the LS7 lifter, but I wouldn't even try them in a Stocker motor.

I have had good success with the racing hydraulic rollers (88958689) to 8,000 rpm with a beehive valve spring. Currently, I am running a Johnson hydraulic roller lifter in my 302 and turning it to 8,600 rpm without issues. Both are full hydraulic, not limited travel.

Re: LS Hydraulic lifter limitations
 

The best guy to field your question is Robin Wright and he is a member here.
He was the guy in charge of the COPO program, a valvetrain expert and also in charge of the engine development for the Corvette and Cadillac LS road racing engines.

Re: LS Hydraulic lifter limitations
 

Yes .I have heard Darren speak of him . Thanks!

Re: LS Hydraulic lifter limitations
 

I currently have LS7's in my bracket 6 liter that we drove with a turbo on the street for 4 years. I've run them up to 72-7300 and haven't run into any issues as of yet. That being said I have two other engines we are doing that have the Johnson hydraulics like Darren along with one that is a low lash solid roller setup.

Rick Ryan

Re: LS Hydraulic lifter limitations
 

Stock LS7 lifters have the best dynamic stability out of any I've tested, and the earlier-version LS7 lifters with circlip axle retention are the ones to have.

Differences in stability of stock vs aftermarket brand "M" and aftermarket brand "J" is not incredibly significant.....Best to worst (stability-wise) is listed in order and again, they are not vastly different. All of this assumes plunger at mid-travel for preload.

Actually in my experience the WORST performing hydraulics (stability, , on a given cam/spring/rocker/pushrod combination) were limited travel units.

If you're hitting a wall at 7000 RPM, you should look at whether you have TOO MUCH spring force (compressing the lifter plunger isn't necessarily the problem.....), too heavy retainer, spring, rocker, or all three, and more often than not the cam lobe geometry itself.

Proper lobe geometry shouldn't require tons of spring force to run well past 8K RPM if it is packaged with light valves (like stock LS) a light rocker (like the stock LS), retainer (again, stock LS), and spring (like beehive or well thought out dual like PSI LS 1512 ML), along with a pushrod that is stiff enough to avoid deflection/energy storage/energy release. This sequence causes bounce at closing and that's when stuff breaks.

Re: LS Hydraulic lifter limitations
 

Mmmmm........to be fair & honest, not really true for those specific programs.

Re: LS Hydraulic lifter limitations
 

ON the short travel hydraulic roller lifters what is the best valve adjustment to get the best performance out of the lifter. Assuming not too much spring rate or valve train weight

Re: LS Hydraulic lifter limitations
 

The GM Performance marketing video seem to imply so when "Bad" Robin was pulling the dyno lever... :D

Re: LS Hydraulic lifter limitations
 

Yo've got that backwards amigo. I'm the good one, the other guy is the evil one, according to his own staff. :)

But - after a week with me they did say the lines between good & evil were very blurry. :D

Re: LS Hydraulic lifter limitations
 

I honestly cannot answer that. I followed the supplier's recommendations and it wasn't as good as a normal full travel lifter with plunger set half-way down.

Someone somewhere may have found a way to make this all work out but it was complex and risky enough for my situation to cause me to stop looking at it once I saw worse dynamics in an otherwise stable setup that would spin clean-clean to well above 8000 RPM.

Re: LS Hydraulic lifter limitations
 

Thanks everybody. To be honest..Ive never even had a valve cover off.
I will get it apart..see whats going on with rockers,springs,etc. check spring pressures and...probably ask for more help.
Rob,Darren .what should I do with the coils? Theyre still on the valve covers.

Re: LS Hydraulic lifter limitations
 

That's where I have all mine.

Re: LS Hydraulic lifter limitations
 

Unless you have a packaging concern I suggest you leave them on the covers.

I've heard some dreamed up "imagineered" reasons to move them but there really isn't any good functional reason why it would be better to put them anywhere besides where GM put them.

Re: LS Hydraulic lifter limitations
 

The best reason I can see to leave them where GM put them is the shortest possible plug wire with less chance to arc to something and with less voltage drop.

Re: LS Hydraulic lifter limitations
 

Yes after further study under the hood,I think you guys are right. No big thing just unplug the harness and plug wires to remove valve covers. I need to stop trying to outthink those G.M.engineers.
Thanks again

Re: LS Hydraulic lifter limitations
 

It's an LS. Why would you have to take the valve covers off?

Al Corda

Re: LS Hydraulic lifter limitations
 

I don't have the budget for that!

Re: LS Hydraulic lifter limitations
 

Robin where is a good source for the PSI LS1512ML? What about a beehive?

Re: LS Hydraulic lifter limitations
 

Ken Juszczyk at Motorsports Unlimited

https://www.motorsportsunlimited.net/

or

Brian Benson at Dakota Parts Warehouse

http://dpwferreavalves.com/

Re: LS Hydraulic lifter limitations
 

I just saw this post... most likely you need more spring and that may fix it,if does'nt have any bent valves... If it was mine, I would throw the hydraulics away, put solids in with .003-.007'' lash...
strongest pushrod,adjustable rocker and enough spring pressure..
I know saying things like that I will have LS'ers telling me how stupid I am.....but thats OK....

Re: LS Hydraulic lifter limitations
 

Agreed with you Mike. If a solid roller lifter is an option in a performance based combination - I would never choose to run a hydraulic.

Re: LS Hydraulic lifter limitations
 

The valve springs on the car were conventional spring with damper non adjustable rockers. The springs were a little weak...I wanted to go with single conical spring like the hemis have,but my engine guy said they're too tall for your valve stems, so I deferred to his judgement and going with new PAC springs with dampers. I only need to get another 4-500 RPM to get to the finish line. I plan on buying a "good" set of heads in the hopefully near future and will set them up with better stuff.