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  • Hydraulic v. Roller lifters

    Holdener did a low v. high compression test (which is interesting) but he said something that defies what I was taught.

    the quote starts about 5:30
    he said that hydraulic lifters create more lift then solid rollers due to lash. I thought that one of the big downsides to hydraulic lifters was that the plunger would compress a bit under load thus reducing the true lift at the valves. With hydraulic, you pre-load the lifter (which creates its own problem at high rpms in losing valve control), thus his statement simply doesn't seem to jive with what I already think I know.... (and it's also why I rarely watch him, most times I catch myself throwing popcorn at the screen because he says dumb things (e.g. the Cadillac builds)

    I also think that by not making the cam/lifters the same in both tests that this is information but not the best information....

    What say you?
    Doing it all wrong since 1966

  • #2
    Thinking about it after what you've said there a a lot of variables, oil viscosity in a hydraulic, how could you measure vale lift on a hydraulic at 5000rpm. Do the cam companies take lash in a mechanical into the final lift figure.
    I've always believed, from what learned, the same cam grind in a solid will make more HP than a hydraulic grind will. The hydraulic may have more lift but the solid more HP. Also a solid RPMs better than a hydraulic.
    Last edited by 65RHDEER; August 14, 2021, 01:33 AM.
    Tim
    Melbourne Australia

    65 Hardtop Impala, 70 GTS Monaro, 93 "80" Landcruiser

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    • #3
      never mind, was gonna post but i dont want to get sh@t on by superbuick.
      Last edited by fatguyzinc; August 13, 2021, 09:14 PM.

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      • #4
        I can only speak for Comp - on their cam cards they publish lobe lift which is then multiplied by rocker ratio. Therefore, they do not publish a net lift (theoretical lift - lash).
        Additionally, it is my understanding that their hydraulic rollers tend to have softer ramps than their solid rollers. I checked this in their master lobe profile catalog for one High Energy grind with the same advertised duration. Finally, I am a big fan of mechanical cams as you can vary lash to hide duration at idle which can help its street manners.

        I would think that a hydraulic lifter would have more variability (good and bad) than a solid.

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        • #5
          What happens to solid lifter lash when the engine is warm vs. what happens to preload on a hydraulic when the engine is at RPM (why do we need anti-pump up hydraulics), how much travel is in the hydraulic being used, and what is the bleed rate? How much preload did it start with? Does oil viscosity have any play here?

          Then again, how much deflection are you seeing in the rocker / pushrod? I'd be more worried about that with a gorilla springed head. Unrelated, I know, but if we're splitting hairs over lift... Seeing that I don't have a Spintron and a 50,000 FPS camera, none of these things keep me up at night poring over an Excel spreadsheet.




          Flying south, with a flock of bird dogs.

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          • #6
            Originally posted by fatguyzinc View Post
            never mind, was gonna post but i dont want to get sh@t on by superbuick.
            I'm such a meanie. Here's a labrador puppy picture to make you feel all better


            Originally posted by cstmwgn View Post
            I can only speak for Comp - on their cam cards they publish lobe lift which is then multiplied by rocker ratio. Therefore, they do not publish a net lift (theoretical lift - lash).
            Additionally, it is my understanding that their hydraulic rollers tend to have softer ramps than their solid rollers. I checked this in their master lobe profile catalog for one High Energy grind with the same advertised duration. Finally, I am a big fan of mechanical cams as you can vary lash to hide duration at idle which can help its street manners.

            I would think that a hydraulic lifter would have more variability (good and bad) than a solid.
            the other elephant in the room is all of those pulls were done between 4k and 7k - basically anything after 5200, at least in my experience, is where hydraulics have trouble with valve control.

            Originally posted by Beagle View Post
            What happens to solid lifter lash when the engine is warm vs. what happens to preload on a hydraulic when the engine is at RPM (why do we need anti-pump up hydraulics), how much travel is in the hydraulic being used, and what is the bleed rate? How much preload did it start with? Does oil viscosity have any play here?

            Then again, how much deflection are you seeing in the rocker / pushrod? I'd be more worried about that with a gorilla springed head. Unrelated, I know, but if we're splitting hairs over lift... Seeing that I don't have a Spintron and a 50,000 FPS camera, none of these things keep me up at night poring over an Excel spreadsheet.
            but that's kind of the point - solid rollers have better valve control (because you can run more spring pressure and stiffer pushrods), yet he's claiming that at speed, hydraulics are better....

            again, it's why I don't watch him - he makes puzzling statements... much like FGZ.
            Last edited by SuperBuickGuy; August 14, 2021, 08:09 AM.
            Doing it all wrong since 1966

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            • #7
              My issue with Rich is that he pretty consistently compares two things (say, a Chevy BB vs a Ford BB) when one has aftermarket heads and the other doesn't or some such. Apples and mangoes. Having worked in dyno testing and sometimes doing A/B tests to evaluate the effect of a change I know you change one thing at a time and keep the test subject as consistent as possible (for example, you only run data when the test cell has the same temp and humidity and the oil temp is the same at the start of testing). He throws 15 variables in there and as a retired pro I can tell you that you cant pick the flyshit out of that pepper.

              Dan

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              • #8
                Originally posted by DanStokes View Post
                My issue with Rich is that he pretty consistently compares two things (say, a Chevy BB vs a Ford BB) when one has aftermarket heads and the other doesn't or some such. Apples and mangoes. Having worked in dyno testing and sometimes doing A/B tests to evaluate the effect of a change I know you change one thing at a time and keep the test subject as consistent as possible (for example, you only run data when the test cell has the same temp and humidity and the oil temp is the same at the start of testing). He throws 15 variables in there and as a retired pro I can tell you that you cant pick the flyshit out of that pepper.

                Dan
                Some of it borders on clickbait, but it's Reduce, Reuse, Recycle. The BBF / BBC vid released recently were salvaged data from tests most likely done years apart. They were not originally made to be a side by side comparison, and even now what he is saying that similar changes make similar HP differences on similar displacement engines. The BBF had some very well ported factory castings, probably better than oval port BBC Edelbrokes or whatever it had entry level aftermarket. With a smaller cam, the BBF made more HP but less torque, not enough to make me very concerned either way. That wasn't the point though. They both wound up pretty close with similar parts. That BBF is long gone, and I doubt the BBC is around any more either unless it was Westech's. You can see the test dates when he pulls up the changes... they can be years, decades almost apart. The SBF head extremes comparo, for example, was done in the very early 2000's for MMFF and was the best SBF head test I've ever seen... he released it on video earlier this year, but it doesn't change the results... at least that's how I look at it. If I remember correctly, they even went so far as to put E7TE's on a 393 to start with the same baseline.. that's dedication, I wouldn't have wasted the gaskets. haha. I don't think they ran that mill with a 192* truck cam though... there's only so much dyno time available.

                SBG, if you listen to him very long at all you'll hear him say (well, he'll say he's repeating Brule) that a hot BBC needs a Solid Roller... although they routinely run LS's up to and over 6500 with what are really pretty mild hydraulic roller cams on a stock bottom end . I think you have to flycut the pistons to put a gnarly cam in one. I'm one of those guys who thinks a smaller cam, less RPM and more cubic inches solves the worlds problems though, as I've had pointed out to me multiple times.

                As usual, my opinion may be exchanged for it's exact cost and shipping is always free.
                Last edited by Beagle; August 14, 2021, 11:19 AM.
                Flying south, with a flock of bird dogs.

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                • #9
                  It is a great mystery of auto mechanics. As soon as you think you have it figured out, you hear people only go a half turn after zero lash instead of a full turn because they say it gives them more lift.

                  But I can round off the #6 lobes on a camshaft no matter what engine I put together. I have even gone to the point of putting a dial indicator on the lifter as I am spinning a pushrod to verify what zero lash feels like.

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                  • #10
                    Originally posted by DanStokes View Post
                    He throws 15 variables in there and as a retired pro I can tell you that you cant pick the flyshit out of that pepper.

                    Dan
                    truth and

                    as I commented on the video - beside him being wrong about the lift - he made the comment that you should do 10:1 compression with blower motors because they dyno said it was better. It's not better, no one races a dyno - on the street, you build in some area where, if you run out of fuel, you can run the local swill and not have the expensive motor melt down in 20 miles....

                    sad, though, it seems that most people never think it through - "Sure, X, is great in a perfect world, but this isn't a perfect world so Y is better (even though it's not perfect)"
                    this is such a common thing these days - people believe the book when not even the author believes what he put in that book
                    Last edited by SuperBuickGuy; August 14, 2021, 01:53 PM.
                    Doing it all wrong since 1966

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                    • #11
                      Your comment about being better on the dyno, is exactly what I was thinking after watching this. The first thing I do when planning an engine, is figure out what it's going to be used for. That determines everything about it.

                      Also he said that higher compression works great with boost...but no dyno test showing this to be the case, nor mention of what it takes to make it work in a real car for a real application.

                      My fabulous web page

                      "If it don't go, chrome it!" --Stroker McGurk

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                      • #12
                        well, i totally get where hes going--remember the old duntov 30-30 cam?
                        used .030 lash both sides. so, using that lash (ridiculous, we used to
                        lash them at 16 cold/12 hot and they ran better...maybe because more lift? )
                        and a theoretical .500 lift cam, you would have .470 lift.

                        a zero or 1/4 turn down hydro might lose .005-.010 with the preload,
                        so .490-.495 lift at the same theoretical .500 ?

                        all i know is-- i run hydro flat tappets because i like them, and they work
                        for me. the new grinds pull WAY farther than 80's tech (a 292/.625/108
                        isky mega hydraulic pulls cleanly past 6500rpm, i can testify to that)
                        and theres the ease of use once broken in properly (set it and forget it)
                        and daily driver reliability. and trust me, a 292/.625/108 idles like a
                        prostocker, and made a TON of hp and torque.

                        plus from what ive heard only the factory or isky redzone roller lifters
                        will live with extended idling/low speed use. i havent run a roller so
                        i cant confirm that, but i know several people who have had lifter
                        problems with roller setup-- enough to scare me off of them for at least
                        a few years untill they work it out.
                        Last edited by fatguyzinc; August 14, 2021, 02:31 PM.

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                        • #13
                          Originally posted by DanStokes View Post
                          My issue with Rich is that he pretty consistently compares two things (say, a Chevy BB vs a Ford BB) when one has aftermarket heads and the other doesn't or some such. Apples and mangoes. Having worked in dyno testing and sometimes doing A/B tests to evaluate the effect of a change I know you change one thing at a time and keep the test subject as consistent as possible (for example, you only run data when the test cell has the same temp and humidity and the oil temp is the same at the start of testing). He throws 15 variables in there and as a retired pro I can tell you that you cant pick the flyshit out of that pepper.

                          Dan
                          I'm with Dan on this one, having built a test cell with him at our old place of employment. It only really sucked when it rained as there was a leak in the ceiling and our controls kept getting soaked. But nevr mind that...

                          one variable at a time and either control temperature and humidity like the diesel cells did, or measure and record the variables and make your important a-b-a tests when the conditions are similar. Oh and no one ever seems to worry about the barometer. To control that requires more$$$ than even the government was willing to spend.

                          And guess what? It's really worth paying attention to...

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                          • #14
                            heh...the barometer will determine whether or not the front wheels go up in the air on my Chevy II.
                            My fabulous web page

                            "If it don't go, chrome it!" --Stroker McGurk

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                            • #15
                              Originally posted by fatguyzinc View Post

                              plus from what ive heard only the factory or isky redzone roller lifters
                              will live with extended idling/low speed use. i havent run a roller so
                              i cant confirm that, but i know several people who have had lifter
                              problems with roller setup-- enough to scare me off of them for at least
                              a few years untill they work it out.
                              I'm thinking about pulling the 427 out of my Corvette this winter to be sure everything is still fine inside the motor - while I'm at it, I may swap the redzone rollers out because the internet rumor (and one I attempted confirm or deny by contacting Isky) is their race version lifters put more oil on the cam - but that makes for low oil pressure at idle. I was trying to avoid a problem someone else had where a roller lifter came apart and filled the oil pan with needle bearings... but we will see, it's running fine now, and 18 psi at idle isn't optimal but it is enough.... I'm not sure I'd ever chance another flat tappet cam - it just isn't worth it. That said, now that the top is lashed correctly, it's been really reliable and I really like it.
                              Doing it all wrong since 1966

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