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  • Dynoed.. finally!

    I'm told this particular dyno (a Superflow SF901) is considered "conservative" and using 600rpm per second acceleration rate, but jeez!

    Eric(68), I just know you're gonna have a field day with this. ;D

    454.. TQ:538.8 @ 5000 and HP:570.7 @ 6250.. (w/o the 2" spacer shown.)

    So, my chassis dyno results of 520rwhp are crap? ..and the Moroso slide rule is engine hp numbers?
    Does this also mean a completely stock ZZ502 would get my 3700lbs to a 10.9 @ 121?
    All sounds a bit fudgy to me. :-X

    Yes, I'm disappointed and not sure of any of the results now. :-\
    I am sure that I fitting a 5000 converter though. ;D

  • #2

    Re: Dynoed.. finally!

    Re: Dynoed.. finally!

    I'd expect more than 538 for the tq on your build. Also, since you lost 80ftlbs between 6k and 7k and only 40ftlbs between 5k and 6k, I'd guess maybe the valves are floating and costing you the hp number you expect? I don't have much experience with big blocks, but it seems pretty challenging getting them to rev into the 6500-7000 range. Were you able to play with any tuning during the runs?

    From what I've read about dynos, there's quite a bit of variability between units, but more so with chassis dynos than engine dynos. Might be time to tweak your trusty slide rule. ;)

    I think it's an awesome venture to try to figure out how much hp gets lost in the car. I was debating doing the same thing, but when I considered how much headache I'd get trying to figure out where the lost hp went and how much I'd spend to find out, I bailed.
    Tampa, FL

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    • #3

      Re: Dynoed.. finally!

      Re: Dynoed.. finally!

      Ye,s the old reliable slide rule is Engine Numbers
      2007 SBN/A Drag Week Winner & First only SBN/A Car in the 9's Till 2012
      First to run in the .90s .80s and .70's in SBN/A
      2012 SSBN/A Drag Week Winner First in the 9.60's/ 9.67 @ 139 1.42 60'
      2013 SSBN/A Drag Week, Lets quit sand bagging, and let it rip!

      Comment


      • #4

        Re: Dynoed.. finally!

        Re: Dynoed.. finally!

        I don't see anything that looks like valve float to me, but maybe I'm wrong. It just looks like a really low compression big block with a solid roller cam. What is your combo? Did you measure compression?

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        • #5

          Re: Dynoed.. finally!

          Re: Dynoed.. finally!

          the converter is what hurts your wheel numbers. Those are actually very impressive for a superflow in "non-dynojet" mode.

          (superflow compares nicely with mustang dynos, so if GoatRacer or CDMBill can chime in here...)
          I'd expect the car to be in the high nines or low tens.




          -scott
          www.realtuners.com - catch the RealTuners Radio Podcast on Youtube, Facebook, iTunes, and anywhere else podcasts are distributed!

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          • #6

            Re: Dynoed.. finally!

            Re: Dynoed.. finally!

            Steve, was it raining in the dyno cell you tested at? I don't think I've ever run an engine with a vapor pressure of .85. I'd also like to look at the uncorrected dyno #'s, not saying anything is wrong but depending on the altitude, temperature, and a few other things (correction factors) that should be done when testing it can give you an idea how accurate the testing was. Erroneous readings would make the test results different next time you tested. All that means is if you took the engine back in 2 months the baseline test should be the same as when you left assuming you made no other changes to the engine.

            One last thing I would point out. The last data line shows a relatively large drop in torq/hp, this could be a sign of valve float. I would work my way up to that engine speed in my car to see if it makes a deference in speed or ET. If it didn't I wouldn't run there.

            Good Luck on your project!
            There are very few people in this world who's opinion I value, you are not one of them.

            300 in 1999

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            • #7

              Re: Dynoed.. finally!

              Re: Dynoed.. finally!

              I don't remember the specifics of your setup, but that sounds a wee bit weak. As stated by Dynoroom, the dip in tq would indicate to me valve float.

              For more of an idea of what's going on, how bout some specs?

              Comment


              • #8

                Re: Dynoed.. finally!

                Re: Dynoed.. finally!

                I would want to see the other numbers, I am not a Dyno guy, but you should have a number  that shows the carbs fuel mixture trending around 49 to 50 to show how close your tune-up is.

                One of the reasons I have not taken my stuff to the Dyno's is they run it up, load it, and turn to you and say, what do you want to do now, maybe not all but the two times I have been thats what has happened. I look at the sheet and say nice print out, what does it tell us to do and I get a shoulder shrug and the clock ticks away.
                2007 SBN/A Drag Week Winner & First only SBN/A Car in the 9's Till 2012
                First to run in the .90s .80s and .70's in SBN/A
                2012 SSBN/A Drag Week Winner First in the 9.60's/ 9.67 @ 139 1.42 60'
                2013 SSBN/A Drag Week, Lets quit sand bagging, and let it rip!

                Comment


                • #9

                  Re: Dynoed.. finally!

                  Re: Dynoed.. finally!

                  Agreed, though the folks in this area with dyno's, are well versed in the tuning process. Can't all be the same though.

                  Comment


                  • #10

                    Re: Dynoed.. finally!

                    Re: Dynoed.. finally!

                    7000 seems as some one would see the outer spring is not on it. LOL (that's a joke) the spring pressure would have to be way off. Its got a 2000 rpm spread on TQ and HP, that seems really tight too. I think more than springs are going to be found. I too, with that many cubes would be disappointed. Whats in this thing, its not like we are going to copy it : LOL (sorry you got to laugh, so you don't cry) what heads, cam and wheres it in at, whats the tune set at? It can be fixed and make more than that. Stick a comp gauge in it and see what kind of pressure you have. Let us know so it can be reasoned out in a responsible way
                    2007 SBN/A Drag Week Winner & First only SBN/A Car in the 9's Till 2012
                    First to run in the .90s .80s and .70's in SBN/A
                    2012 SSBN/A Drag Week Winner First in the 9.60's/ 9.67 @ 139 1.42 60'
                    2013 SSBN/A Drag Week, Lets quit sand bagging, and let it rip!

                    Comment


                    • #11

                      Re: Dynoed.. finally!

                      Re: Dynoed.. finally!

                      7000 seems as some one would see the outer spring is not on it. LOL (that's a joke) the spring pressure would have to be way off. Its got a 2000 rpm spread on TQ and HP, that seems really tight too. I think more than springs are going to be found. I too, with that many cubes would be disappointed. Whats in this thing, its not like we are going to copy it : LOL (sorry you got to laugh, so you don't cry) what heads, cam and wheres it in at, whats the tune set at? It can be fixed and make more than that. Stick a comp gauge in it and see what kind of pressure you have. Let us know so it can be reasoned out in a responsible way

                      Well worded. Something has to be off, for sure.

                      Comment


                      • #12

                        Re: Dynoed.. finally!

                        Re: Dynoed.. finally!

                        Well since you are obviously "calling me out" Steve I guess I need to respond. ;)

                        Your engine dyno HP and ET slips line up!!! In fact your engine dyno HP is within 20 HP of what I predicted it would be back in 2005!!! Looks like you found another 20 HP since then . . . LOL. Here's what I said back then in case you forgot ;)

                        Your "chassis" dyno is ROUGHLY estimating FLYWHEEL HP but is not considering frictional losses in addition to converter slip. The reality of the matter is that your flywheel HP is probably closer to 550 (if you back out a couple percent for frictional losses) and your rear wheel HP is probably down closer to the low 400's that Luccocamaro's engine is running.
                        While the engine dyno and the ET line up, your chassis dyno numbers still do not because as I've explained before you cannot correct chassis dyno numbers for "converter slip and drivetrain losses" and claim them as rear wheel HP. When you introduce a correction for drivetrain losses you are actually estimating flywheel HP and with using only 7% for a correction it is an incomplete conversion. I think you wound up with a chassis dyno number that lies somewhere in between rear wheel power and engine dyno power.

                        I hope you find some big HP with the tuneup Steve -- maybe valve springs like the others said???

                        Merry Christmas guys!

                        Comment


                        • #13

                          Re: Dynoed.. finally!

                          Re: Dynoed.. finally!

                          Well since you are obviously "calling me out" Steve I guess I need to respond. ;)

                          Your engine dyno HP and ET slips line up!!! In fact your engine dyno HP is within 20 HP of what I predicted it would be back in 2005!!! Looks like you found another 20 HP since then . . . LOL. Here's what I said back then in case you forgot ;)

                          Your "chassis" dyno is ROUGHLY estimating FLYWHEEL HP but is not considering frictional losses in addition to converter slip. The reality of the matter is that your flywheel HP is probably closer to 550 (if you back out a couple percent for frictional losses) and your rear wheel HP is probably down closer to the low 400's that Luccocamaro's engine is running.
                          While the engine dyno and the ET line up, your chassis dyno numbers still do not because as I've explained before you cannot correct chassis dyno numbers for "converter slip and drivetrain losses" and claim them as rear wheel HP. When you introduce a correction for drivetrain losses you are actually estimating flywheel HP and with using only 7% for a correction it is an incomplete conversion. I think you wound up with a chassis dyno number that lies somewhere in between rear wheel power and engine dyno power.

                          I hope you find some big HP with the tuneup Steve -- maybe valve springs like the others said???

                          Merry Christmas guys!

                          CDMBill and Goatracer both lost somewhere around 35-40% between engine dyno numbers and chassis dyno. I am hoping they see this thread. Again, your chassis numbers aren't bad IMO. The car should haul ass. What does/should it run in the quarter? (Sorry I am not up to speed on your combo...)
                          www.realtuners.com - catch the RealTuners Radio Podcast on Youtube, Facebook, iTunes, and anywhere else podcasts are distributed!

                          Comment


                          • #14

                            Re: Dynoed.. finally!

                            Re: Dynoed.. finally!

                            I know NOTHING about your combo so I can't comment of the HP/TRQ #'s, but I CAN say that using 600RPM per second rate is way to fast to get an accurate read on anything, in my opinion.. I use 300RPM per sec., and if I REALLY wanna get serious I use a step test, but you better hold on to your seat cause it can be unnerving to the casual observer.. lol I have had a SuperFlow 901 for about a dozen years, they work well and for many years the standard in the industry that others have built by.

                            An engine dyno can be humbling, thats for sure.. When guys sit down over a few beers it seems that over time their engines make more and more power, but when they get them on the dyno they are more often then not a little disappointed..

                            As far as the vapor pressure being .85, it has been that and above around here on MANY occasions.

                            Comment


                            • #15

                              Re: Dynoed.. finally!

                              Re: Dynoed.. finally!

                              520 to the tires isn't anything to scoff at that' s for sure. With that race weight and everything set to go I don't see why mid to bottom 10's are out of the question given your short game is in the good.

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