Pauerman

Doesn't seat pressure play a big role in the overall boost you can run?

I just measured a set of used stock springs and they exert approx 90 lbs of seat pressure at 41mm spring height. The engine builder I deal with recommends going to a spring that makes 120 lbs of seat pressure if you're looking to run higher boost. He feels that this is the maximum you can go with a hydraulic setup cause above this seat pressure, the hydraulic lifter will most likely collapse before moving the valve. Of course, the ramp angle(s) on the cam also plays a roll in the lifters performance, but as a general point the 120 figure is what he's usually run on high output engines.

As a reference, I'm running 150 lb springs in my solid lifter head.

What does modding the stock lifters involve? I'm guessing that you must cut down the "skirt" area of the lifter to accomdate a higher lift cam - no??

Laust Pedersen

It does require more tools and time than I have to go through a full analysis of the max safe boost for the OEM valve train, but as seen in my signature I do routinely run 25 psi boost, which maybe 21-22 psi at 6000 rpm and I have not heard or seen any signs of valve float (OEM valve train, the springs may have been refreshed, but not “upgraded”).

Florensic?? There is not much flora in a forensic investigation.

Laust

RKD in OKC

It is not like you go over 16 psi once and the lifters are immediately cratered. Especially if you have the original factory lifters which are much harder than the replacements available today. And even though you are running boost of 20-21 psi, how many actual driving miles is spent in boost above 16psi.

tick tick tick.

Jon Moeller

F(l)orensic

I have no doubt that the factory lifters were being hammered in the application that Lindsey used them in. However, trying to equate the failure of the lifters to a given level of boost is a great attempt at arguing against the laws of physics. Regardless of what you're being told, the amount of pressure in the intake manifold had jack **** to do with the failure of the lifters. The lifters failed due to the aggressive cam that was being used.

Greater levels of boost in a turbo-charged car will not have any impact on the amount of pressure being placed on the back of the intake valve.
-Jon

Porschefile

Damn! Can I have another serving of reality waffles please?

Chris White

Yeah, sure- just you wait until I get the 50 psi manfold pressure engine running, then I will be able to lift those valves....

Jon Moeller

Chris,
Just because you're trying to defy the laws of physics with your engines, doesn't mean you actually are.

I apologize for never getting back to you on the MID block. With my usual scatter-brained nature, I decided to go with Bret's pistons. If I focus on building the damn thing, you might actually see the results at GVC's WGI event.

-Jon

RKD in OKC

Oh yeah, right. The stock cam on my 89 is really freakin aggressive...3 failed lifters after 13,000 miles running higher boost levels and one of them a brand new INA replacement. Thankfully it was caught before the lifters completely cratered and pitted the cam. It will be interesting to hear the waffling after a couple more years of people running higher boost levels. tick tock tick tock...tick tick tick.

florensic - yes I do typo, and no I do not spell chck.

Chris White

You've seen me drive....!

Laust Pedersen

Three years with 25 psi and no sign of valve float audibly or visibly (on the lifters or cam). How many more years do you want to wait?
Of cause I don’t run max boost all the time, but do get up there quite often just because it is fun.



You better check your lifters, they appear to be quite noisy.

Laust

RKD in OKC

I did mention miles under boost over 16psi in my car, my reference to years should have been miles...

Continued good luck to you sir.

Porschefile

There are plenty of other people around here that seem to be running anywhere from ~16-21psi (18psi seems pretty common) on stock valvetrains, and I've rarely ever heard of lifter problems, except for those associated with the lower quality INA stuff. Maybe your motor is the exception or else maybe you just have bad luck.

RolexNJ

Going OT here, but, I think I'll add my own experience to this. I've had "3" brand new sets of INA lifters be bad right out of the box as Richard said. LR and I tested and saw them when we were building my old 3.0L 8V. We found Travis over 80% of brand new INA lifters to be soft, hence bad. I actually have photos from engine with only 2K on the rebuild, and you could see how badly damaged the lifters were. Anyway it was this discovery that prompted them to look into the development of a solid lifter conversion kit. So you will hear more and more about lifter issues with newer production INA lifters. Maybe you're one of the lucky ones who just hasn't had to buy new lifters and had issues yet.

Porschefile

I'm lucky I never had any issues with lifters, even up to ~220k miles. I hear about this more and more, so it certainly sounds like it's a serious issue. Seems like there is less and less of a reason to not go with solid lifters.

RolexNJ

Youre right, stay with what you have and in the Maxima too baby!