1990 300ZX NA tune-up

Discussion in 'Technical' started by ztothebone, Aug 27, 2018.

  1. ztothebone

    ztothebone Member

    I have a 1990 300ZX Auspec NA which is running well, but I would like to improve the gas flow through the engine without major expense.
    The engine is basically stock, except for a Fujitsubo 2.5" cat back exhaust system which I had fitted some time ago.
    I have now acquired a set of new Advance headers which I propose to get ceramic coated before fitting them. I will also fit two new oxygen sensors while everything is easy to get at, as well as a cold air intake cone air filter under the front panel.

    I would appreciate any advice on whether it is it necessary to get the engine retuned once all this fitted.
    Is there any benefit in testing this on a dyno?

    Thanks
    Paul
     
  2. East Coast Z

    East Coast Z Well-Known Member

    Here's a tip.
    BEFORE you do any of the proposed mods, run it on the dyno & get a printout of the results.
    AFTER the mods have been completed, take it back to the same dyno & rerun it again.
    Upon completion of the above, compare the two results.
    I'll bet you'll be disappointed...................
     
  3. Martin Williams

    Martin Williams Well-Known Member

    Great mods to do if all you want to do is talk about them over a couple of beers with mates! Gas flow limitations on these engines is in the heads, so unless you are going to upgrade camshafts/valves, clean out ports etc, you are wasting your time and money, in my opinion.
     
    East Coast Z likes this.
  4. ztothebone

    ztothebone Member

    Thanks for the feedback. So in addition to getting a port and polish done, what would you be suggesting for upgrading cams and valves? I appreciate that I have an NA, so I am only looking for modest performance improvements.
     
  5. East Coast Z

    East Coast Z Well-Known Member

    Why are you looking for performance improvements in your NA?
    What are you trying to achieve?
    Honestly, if you want an increase in performance, sell your NA & buy a TT.
    It may seem a harsh statement, but you will be better off choosing that route, rather than modifying the NA.
    The expenditure on getting a TT could work out similar, or maybe even a bit cheaper, than modifying the NA.
     
  6. harty

    harty Member

    East Coast is spot on. Either appreciate the NA for what it is or if you’re determined for more power go get a TT.

    I started off with a NA and still enjoy it for what it is despite my TT making roughly double the power, they are two different beasts accept the NA limitations and be happy powering through corners or sell it and get a TT.
     
  7. scottyoz1962

    scottyoz1962 Active Member

    I agree with Martin & Harty, unless your prepared to spend some serious $, by getting the engine out, port, polish and blueprint the heads, cams etc , exhaust upgrades , pod filter , etc the improvements are only going to get you maybe 5-10% increase. If you only want a bit of an increase, but a noticeable one get a stock as a block TT motor.
     
  8. stumagoo

    stumagoo Active Member

    I would add - if you are on your P's save the money and buy a TT when you are on your full..... as others have said the NA is all about the style and is pretty much spot on for what power can be made easily out of them. unlike the TT which has a fair amount of potential that is easily unlocked
     
  9. stumagoo

    stumagoo Active Member

    if you want more detail have a look here >>http://www.pexcom.com.au/images/dynolist.htm << sure much of it is out of date links but the worst TT's are only just worse than the best NA's there. There are bound to be worse TT's out and about and maybe there are some better NA's but I bet a fair amount that the NA's at the top of the list have a lot more in them dollars wise than the TT's at the bottom
     
  10. Martin Williams

    Martin Williams Well-Known Member

    The question you have to ask yourself is.....What am I going to do with any extra power that I get? If you are only going to use it legally on public roads you have more than ample power already. If you want to put one on the track, get a TT and be prepared to spend over $30K on improvements just to be at the rear of the field. The NA is a great fun car to drive. Instead of looking for more power, why not look at improvements to tyres, suspension and braking giving you better roadholding not just straight line speed. Put a TT front bar on it and a couple of TT stickers and 99% of people wont know the difference. You sound like you have a good car, just enjoy it, don't make it a money pit.
     
  11. East Coast Z

    East Coast Z Well-Known Member

    The guys replying to your questions have been on the forum for quite a while.
    A lot of people have come & gone over the years & when you've been involved with these cars you learn a few things along the way.
    There are a couple of ways to learn about these cars.
    By making mistakes yourself, or learning through the mistakes of others.
    One is significantly cheaper than the other.

    NA's Z32's are a great car, sure they may not accelerate as hard as a TT, but they'll do everything else just as well.
    Martin's correct, spend your money on a good set of tyres & enjoy your ride.
     
  12. ztothebone

    ztothebone Member

    Thanks for all the replies above. I really appreciate you all taking the time to respond and I hear your collective wisdom.
    I certainly don't want to over-capitalise on my NA and I don't want to go down the TT path either. I was really just exploring what I could do to improve acceleration off the line without major outlay.
    I have to admit I was thinking back to the days when I had my first sports car, an MGB. I loved driving that car and to give it some extra zing I put a 3/4 cam, competition valve springs and nitrided pistons in it and ran it on 50% methanol. This was back in the day when methanol was readily available from Shell service stations. Not an expensive upgrade but a significant improvement in performance.
    I will take your advice on tyres. I am currently running Falken Ziex ZE912 225 R16 tyres on oem rims. However, I don't put large mileage on my tyres, so although my existing tyres still have plenty of tread, they are getting on for 10 years old. Any thoughts on what new tyres to put on original 16" rims?
    Again, many thanks for all the constructive feedback.
    Cheers
    Paul
     
  13. scottyoz1962

    scottyoz1962 Active Member

    Steer clear of directional tyres, as you can't do proper rotations. Any half decent good year, or bridgestone, even the falkens are good.
     

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