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Replacing Turbo engine with NA engine

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  • Replacing Turbo engine with NA engine

    Advice needed.

    I have owned a 1986 300zx Turbo for around a year now. And would like to say they are by far my favourite Japanese car. Not to mention (at least where im from) absolutely unbeatable in terms of massive value for money. One day I plan on Building The Australian version of the z31, Using an RB30DET... but yeah, that will never happen. And I like the earlier vg30 equally as much.

    The car has never ran properly since I have owned it. It has always had a misfire and ran lean under boost. It also Idles high.

    I recently Changed the timing belt and installed new stock turbo injectors among other things and noticed that the left hand side cam seemed to have an amount of play before the gear actually revolved the cam. I think its because It has been driven so long misfiring on that head (6th cylinder was not firing).

    Anyway although it made a huge difference it still has the underlying leaning out/hesistation. I have put it down to the fact that the previous owner obviously has driven it unkindly etc, and thought that it could really do with a complete rebuild.

    Anyway to the point, I need to drive the car, and after looking around have found a VG30E which appears to be out of a Nissan Gloria (Judging by the intake manifold) and have thought of taking the current engine out and installing this engine, bolting the existing turbo exhaust manifolds, intake, oil lines ect to it while the original engine is getting rebuilt.

    Now after some research i found that it has been done, being realistic Im not expecting 2000 horsepower out of it, but how does the car drive with a turbocharged NA engine??

    I just want it to be reliable untill the other engine is ready.
    Thanks for any help.

    Oh yeah, just thought Id add Id be running Premium fuel, which is 98 octane. Hopefully it helps with the higher compression.

  • #2
    I really don't see why not, but don't listen to me.

    Terrible idea putting those wheels on...


    • #3
      Have you checked the current engine's compression? How about the MAF?

      Lots of people are running 9:1 NA blocks with stock turbo equipment now. As long as you run good gasoline (I ran US rated 93 octane) and set the timing properly you should not have any knock issues. It's really the best of both worlds in my opinion.


      • #4
        Yeah, When i very first got the car I had a workshop go right over it, they said that the compression was fine. They pinpointed the injectors to be the problem, and I have since had the full set cleaned and as i stated found that the wiring to the sixth cylinder was broken. Its not misfiring anymore but its still running really bad. I got a replacement AFM and it made no difference. I was watching the timing with my timing light and it drops out irratically. I'm really sick of trying to find the problem which is why Ive considered rebuilding it.


        • #5
          Ran codes yet?


          • #6
            Yeah the only code that was out of place was the ignition code, But ive checked all the things i thought it could be, someone suggested to me to check the Crank Angle Sensor, But i would think it wouldnt run at all if that was the problem. And there was no fault code for the crank angle sensor in the diagnostic mode. The manual says that the ignition code means, "The ignition signal is not entered during engine cranking/running" WTF? I dont understand it.


            • #7
              Code 21, this is definately your problem. Someone with a little more experience on this will help you out better than I can, all I'd suggest to do is replace the perishables relating to the ignition such as wires, plugs, cap, rotor etc

              By the way, there's no Z31's here in Australia with the RB30DET, infact there's no Australian Z31's with the RB at all only the 200ZR which is imported from Japan. And more importantly, no car period came with the RB30DET from the factory as it technically doesn't even exist.

              No official version exists but it is referred to by tuners as the engine can be bored to 3 liters. Also refers to a turbocharged engine featuring an RB30E block with a twin-cam head conversion. Common hybrid in Australia using a RB30E bottom end mated to a RB25DE cylinder head and turbo. The RB25DE cylinder head from the R32 Skyline, A31 Cefiro or C33 Laurel can be used. The RB25DET (from the R33 Skyline or C34 Laurel or Stagea) head is also used, however an external oil feed must be fabricated for the variable cam timing on the RB25DET which further compicates things.


              • #8
                Ive checked the wires from the crank angle sensor to the ECU, and theyre fine, The Manual suggests the Primary Circuit which is the larger of the two. Is there any that go to the ECU other than the Crank Angle Sensor wires which would cause an ignition fault?.

                Yeah im not totally stupid :roll: lol no offence. I meant an "Australian" version (which doesent really make any sense because the engine was manufactured in Japan as was the Z31). But what i was getting at was that Australia was one of the only countries to recieve the RB30. And im very familiar with the 200zr as a friend of mine has one. And yes, the RB30DET was never a nissan engine. As you said, its just a name given to the engine when a 20/25/26 twin cam cylinder head is installed. And come to think of it its really not even worth the money seeing as the 2 valve heads have been proven to be able to make equal or more power than the twin cam heads for less money. Who needs twin cams?

                I WAS BEING STUPID lol

                Anyway getting away from the matter. Thanks for the correction.

                :lol: :lol:


                • #9
                  don't be silly, an rb30det would own your pants

                  consider some equal length turbo header and a high flowing intake on the other side.... perfect for i/c piping etc....

                  that thing would scream "beat me"


                  • #10
                    Sorry I should of been more clear, spark plug wires/leads I was referring too...

                    The RB30 was never in any Z's either, that's a dog slow engine in stock form used in non turbo Skylines here in Australia. My Mums Skyline Ti has an RB30, it goes "ok" once you get the rpms up there but that takes a good while! And the 200ZR used an RB20DET which is a different monster yet again.

                    Anyway back to your problem, replace the spark leads... We call them leads here, in the US most people refer to them as wires, why I dont know. Lots of things like that dont translate well here, like downpipes are on the side of a house, not in an exhaust system lol And the "02 housing" is really a "dump pipe" which contains a "waste gate" lol Can't really call it 02 housing when most cars have the 02 sensor in the cat? lol I'm just being stupid now...

                    Ignition perishable replacement, at least to count them out as issues...


                    • #11
                      Well I was serious. Ive had the idea for a long time. But the fact i havent got enough money to waste on all the little things id need means it will stay an idea for now. It would be sweet though you are right. Modified VG30s are far rarer here, the average guy doesent know what one is. Unless hes into older Zs.At least one thats not out of a Z32 and can actually be worked on. The Rb30s dont have the seemingly constant torque of the VG30 though, ive been in some pretty fast RB30 powered cars, and the power is not there untill there revving real hard. Not that thats bad at all, I love the Rb30 with a passion, but VG30s are new to me. And from what ive sen so far the two engines seem to have different ways about making power.


                      • #12
                        I have a friend running 12's with a highly modified RB30ET in a Holden VL Commadore but with that said, stock vs stock the VG30E Z31 is faster than the RB30E Skyline mainly due to the power to weight ratio from my understanding. But you're right in the fact that they're totally opposite styles of engines with the VG being more torquey and the RB red lining far later.

                        I wouldn't bother converting a Z31 to an RB here in Australia, forget what the yanks say. To them it's real special, here's it's straight up dull and boring! There's no easy way to put it, RB's are just too common. Spend the money on your VG, forget about the RB unless you import a 200ZR directly. It's seriously not worth the trouble if you ask me because at the end of the day all you have is another boring RB powered car on the road to match all of the thousands of others out there.


                        • #13
                          Yeah thats exactly how i think, Its so original over here. People have no idea of the kind of power produced from such a potent engine as the single cam VG30. Far different from what theyre used to in their RB26s.

                          This is what ive done. to clarify...

                          Replaced Timing Belt and Timing belt Tensioner
                          New Plugs
                          New Leads
                          New Distributor Cap
                          New Rotor button
                          Removed All six injectors and had them cleaned and the flow tested. Reinstalled them with new Fuel injection hose and clamps
                          Repaired broken Fuel injector wires
                          New Throttle Position Sensor
                          New Air Flow Meter
                          New Water Pump
                          New Thermostat

                          Still runs like a dog.


                          • #14
                            If you've done all that and you still get code 21 i'd be leaning towards a screwy distributor although I'll leave it up to the more expert users on here to troubleshoot that exact problem further for you. One thing though, what timing do you have it set at?

                            *Here's my mates RB30ET VL for what it's worth, it actually runs 10's @ 700HP on pump fuel now he tells me since the Nizpro intake upgrade and some other new gear...

                            Lots of money spent on this thing, and I mean LOTS! lol



                            • #15
                              Jason84NA2T wrote: Have you checked the current engine's compression? How about the MAF?

                              Lots of people are running 9:1 NA blocks with stock turbo equipment now. As long as you run good gasoline (I ran US rated 93 octane) and set the timing properly you should not have any knock issues. It's really the best of both worlds in my opinion.
                              What timing would you recommend? I just finally completed this swap last night. :lol: