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  • recommendations please

    Ok I'm looking for some tips/recommendations here. My car runs great except it falls flat above 6,000 rpms in 3rd / 4th gears & even 2nd gear sometimes. My dyno chart shows how power just drops off the map at 6,000rpms.

    1. where should I attach some ground cables to ensure my car is grounded well??

    2. My OEM Nissan plug wires have 27,000 miles on them. Bought them new when I rebuilt the engine. Should I replace them? Stick with factory wires or do you recommend something better??

    3. JWT told me to run z32 NA plugs with my set up. Should I keep those or are you guys running something that works better. My gap is .28 right now.

    4. JWT told me to run fuel pressure at the stock 36psi. Should I or have you guys found it better to run a different pressure??

    Anything else I haven't thought of??

    I have 3 races next weekend. Drag racing Fri. night, road course Sat., & autocross on Sun. I'm running with a 300hp Miata, 450hp TT 350z, turbo MR2, turbo Elise, 200hp CRX. Some fast cars. We are adding all 3 times together. Lowest overall time wins. I need/want all the power I can get.
    378whp 445wtq
    http://mark86t.zmobiledetailing.com/.../v/Black+Hole/


    Z Mobile Detailing, Las Vegas, NV

  • #2
    if you can go around the engine bay and check/clean every ground strap there is.... secondly run a bunch of new ground wires from those locations back to the transmission where the battery ground goes (behind starter)

    the key point here is to spread the main ground point (engine) to the rest of the car (body) as much as possible, and as close to the existing points where the harness is grounded to give them a sort of highway without congestion/resistence back to the battery

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    • #3
      I can't think of ANY ground wires on the engine except for the battery to starter. I have had my engine out a couple of times. Where are the other ground straps?
      378whp 445wtq
      http://mark86t.zmobiledetailing.com/.../v/Black+Hole/


      Z Mobile Detailing, Las Vegas, NV

      Comment


      • #4
        There are a couple others on my 84. Just off the top of my head, one behind the battery, 2 off the wiring harness to the upper engine. I believe one grounds to the plenum and the other to the rear firewall?? There are probably a couple other smaller ones I am forgetting right now. :?

        Upgrading to some large grade + wires for the charging system/battery and large grade - wires for the grounding points cant hurt. The wire isn't cheap but I'm betting that it will be worth the money. (20 year old cables vs new and improved???)

        I havent done it yet but I have the wire and connectors to do it this winter. :wink: It isn't cheap if you get quality wire but I am guessing that it will be worth it in the long run.
        Just stand back and throw money.
        Performance costs money.
        Reliable performance costs more.

        Comment


        • #5
          I was into telecoms the past couple years, paging systems, phone stuff... you'd be surprised how cheap it can be....

          run a 4awg for the main trans ground to somewhere convenient out front, run a bunch of 18awg 600v 2 conductor from there to all the other body grounds.... probably the cheapest wire you can get shielded no less... all the 70v paging systems use it

          Comment


          • #6
            Mark, I think your primary issue might not be where you are looking. To begin with, your valvetrain and cam timing have the most to do with the overall shape of your powerband. You could be encountering valve float with stock valve springs. What tends to happen on boosted engines is the boost pressure will actually tend to make intake valves a little more bounce-happy, and higher pressures can make them float at even lower RPM. You should be able to figure if you have a boost-related valve float issue by revving the engine out at something like 8PSI and your set 17PSI to see if there is a difference in the end shape of your powerband.

            Are you getting any miss or breakup around 6K? If power falls off and that's it then your ignition system is probably fine.

            The stock engine grounding was enough for me to make 418rwhp, but I recently added a grounding strap from the drivers side head to the body. I noticed absolutely no difference. You can see it in the post I made about the MSD install.

            Our engines also like a fairly rich mixture and a lot of timing in the top end, if you're not meeting those requirements the power will fall off quickly. This is still where I think most of your problem lies. Not engine grounding, or ignition related.

            How thick are those copper head gaskets you are using? If anything but stock then your cam timing is off and you will need to individually degree them before making timing adjustments.

            G-E wrote: I was into telecoms the past couple years, paging systems, phone stuff...
            Heh, funny because I work for a telecommunications company.

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            • #7
              Heh, funny because I work for a telecommunications company.
              really, doing what? I was an onsite installer, fixed some huge jobs by myself for them, govt buildings and such.... good thing wires and dirt don't scare me

              Comment


              • #8
                G-E wrote:
                Heh, funny because I work for a telecommunications company.
                really, doing what? I was an onsite installer, fixed some huge jobs by myself for them, govt buildings and such.... good thing wires and dirt don't scare me
                I'm in network engeneering, so I work the backend and am primarily what most people call a "data tech" for onsite installs. Servers, wireless bridges and access points, VPN, web appliances, etc. I also handle all of the companies internal support items for all of our locations. Tehpopa is a lead telecom installation engineer, or "phone tech" onsite. He also handles a good portion of our Cisco installations. We used to sell everything from Avaya to Comdial, and MAC/service anything under the sun... but our company has recently gone Inter-Tel exclusive for new sales.

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                • #9
                  Jason84NA2T wrote:
                  Are you getting any miss or breakup around 6K? If power falls off and that's it then your ignition system is probably fine.

                  Our engines also like a fairly rich mixture and a lot of timing in the top end, if you're not meeting those requirements the power will fall off quickly. This is still where I think most of your problem lies. Not engine grounding, or ignition related.

                  How thick are those copper head gaskets you are using? If anything but stock then your cam timing is off and you will need to individually degree them before making timing adjustments.
                  No break up or miss, power just falls off. Car will still rev past 6k but power is gone.

                  When you say timing in the top end, what do you mean?

                  Copper head gaskets are stock thickness.

                  I really appreciate you taking the time to help me sort this out. I am going to another dyno next Thursday. Mustang dyno. Was there today with my friend's CRX on the dyno. (197whp) Guy asked me a lot of questions & seems to know a lot. He agreed that my car should dyno more than the 274whp I got. He too wants to get a base run & see how far off his & the other dyno are. Then it's more tuning. He mentioned that advancing my cam timing would move my power band up in the rpm range. I only retarded my cam timing as I didn't know what else to do & neither did the first idiot I took it to. I'm hopeful that this guy will get even more out of my car. Thanks again for all the help.
                  378whp 445wtq
                  http://mark86t.zmobiledetailing.com/.../v/Black+Hole/


                  Z Mobile Detailing, Las Vegas, NV

                  Comment


                  • #10
                    He mentioned that advancing my cam timing would move my power band up in the rpm range.
                    the opposite

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                    • #11
                      G-E wrote:
                      He mentioned that advancing my cam timing would move my power band up in the rpm range.
                      the opposite
                      Guess I got that wrong. I should either listen better or take notes.
                      378whp 445wtq
                      http://mark86t.zmobiledetailing.com/.../v/Black+Hole/


                      Z Mobile Detailing, Las Vegas, NV

                      Comment

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