Full undertray ? | The Z Club of Great Britain
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Full undertray ?

Discussion in 'S30 (240Z / 260Z / 280Z)' started by SeanDezart, Oct 6, 2009.

  1. SeanDezart

    Z Club Member
    Official Trader

    What might be the advantages (disadvantages ?) of a full under engine tray ?

    Better airflow to drag hot air away from the engine = better cooling ?
    Better airflow for less drag around the baulkhead = more aerodynamic ?
    Keeps engine bay cleaner ?
    Protects sump and accessories from knocks, stones etc ?
    Looks better ?

    In what material ?

    Plastic ?
    Fibre-glass ?
    Metal ?

    Obviously quick and easy to take off for servicing etc. perhaps with certain cut-outs ?

    Mounting where and how ?

    Mounting points susceptible to rust ?

    What do you think ?
  2. johnymd

    Z Club Member

    There is a fair bit on the HybridZ site about this..........I've been looking and thinking about this as well. Along with a rear diffuser. The main reason cars have these is for ground effect. Cutting holes in it to extract air from the engine bay will have an adverse effect on the ground effect you are trying to create........I think.

    But I could be wrong. Very interesting subject though.
  3. grolls

    grolls Well-Known Forum User

    mmmmmm interesting. What I can confirm is with engines be it cars, aircraft or bikes,
    1/3 air intake to one part( 3 thirds) air exit would equal the perfect air flow.
  4. SeanDezart

    Z Club Member
    Official Trader

    So 1/3 air intake and 2/3 exit ? Not sure that I follow correctly here Paul......:unsure:

    Going back to openings for air exit etc, the standard stray that we've all taken off and not put back served to pass air underneath (I believe ?) so something must be better than nothing.......no ?

    What if a tray was as wide as the space between the two front chassis legs and up to and around the radiator but then as each side went towards the baulkhead, each side slimmed inwards towards the engine so that when the tray was attached to the baulkhead, there are just two 'arms' each side of the gearbox ?

    Looking at mine up on the ramps, I now wonder if one can have anything larger than the radiator with (again) two 'arms' running each side of the engine to attach to the baulkhead.....
    Last edited by a moderator: Mar 13, 2010
  5. 2fast2z

    2fast2z Well-Known Forum User

    Sounds interesting, i'm going to follow this topic.
    It's not to jack this topic, but i don't have the original tray so if anyone got a spare, please let me know.

  6. Albrecht

    Albrecht Well-Known Forum User

    Gazundheit! :p

    Meanwhile, back in 1969, the 432R model had a full engine and trans under tray ( aimed at addressing 'air flow' ) made from FRP.

    Quite a lot longer, and with a different set of functions, than the pressed steel 'splash pan' on L-gata engined models......
  7. SeanDezart

    Z Club Member
    Official Trader

    Ooh arrh !

    Pretty please may I see a photo of said, my Count ?:bow:
  8. grolls

    grolls Well-Known Forum User

  9. SeanDezart

    Z Club Member
    Official Trader

    Yes, that's why I'm asking here.

    So, a wide tray at the front running from the rad. support panel to just behind the steering/suspension (with cut-outs of course) might suffice to produjce a 1 - 3 ratio ?
  10. Albrecht

    Albrecht Well-Known Forum User

    This is not a photo ( don't have one to hand right now ), but an illustration from the Japanese parts manuals. Gives a good indication of the difference in size compared to the ordinary steel 'splash pan'.

    The PZR's ( FRP ) front valance was specially shaped to accomodate this.

    Part number 14:

    Attached Files:

  11. Rob Gaskin

    Rob Gaskin Treasurer Staff Member Moderator

    I would think the main benefit of a large flat undertray would be to do with aerodynamics. But to be honest are our 240s going to gain much from this?

    Surely you would need to make radical changes to notice any difference e.g. Ben and DJs Modsports race cars. Better to experiment with a G nose, front/rear spoilers and ride height.
  12. SeanDezart

    Z Club Member
    Official Trader

    It'a also cooling, Rob. And Z432-Rs didn't (all ?) have G-noses and spoilers etc........;there must have been a good reason. I like the idea so I'm gonna look closer at doing something on mine.
  13. ben240z

    Z Club Member

    Be careful playing around with this. You do not have to get the angle or shape of the under tray too far wrong before it all goes horribly wrong. If too much air goes under the car then an undertray can act as a wing and then the front goes very very light and scary.
    Look at flat bottomed cars on the race track and see what happens when the air gets under them. I know that race car undertrays are more extreme than a road car under tray but the principle is the same.
    Aerodynamics will start having an effect after about 60mph(shoot me down in flames with maths and calculations but in the real world I have had it happen)
    What are you going to do with the air that you have dragged out of the engine bay with your undertray?

    It has to go somewhere and leaving it to find it's own way out from under the car can be interesting and certainly keep you focused.

    I watch with interest and bated breath
  14. grolls

    grolls Well-Known Forum User

    I guess you would have to get your ruler and calculator out. I can only guess that as Nissan did do this at some point we can safely assume the researched it first. Perhaps some research, perhaps a search of the japanese forums may shed some light?
  15. Rob Gaskin

    Rob Gaskin Treasurer Staff Member Moderator

    I don't have an engine cooling problem, tbh I'd rather spend time on brake ducting. Good luck!
  16. datsun dave

    datsun dave
    Z Club Member

    If it aint broke don't fix it.
  17. johnymd

    Z Club Member

    Sorry Dave but I couldn't disagree more.

    I believe everything is "broke" to a certain degree and can be fixed by modifying/improving/developing and this is what makes things better.
    Makesy and strugrat like this.
  18. Sylv1

    Sylv1 Well-Known Forum User

    It is one of my secret projects to beat the Cobra at LeMans Classic ;)

    and keep engine bay clean :D
  19. Rob Gaskin

    Rob Gaskin Treasurer Staff Member Moderator

    I bet PMac will be selling full undertrays soon at a 'bargain' price made out of the remains of 'cut-up' Z bodies :smash:
    A well researched undertray MAY offer benefits but the time and money would be better spent of trackdays :driving:.

    However some people just love projects :bow:

    Good thread Sean - things were getting a bit quiet on here.
    Last edited by a moderator: Oct 7, 2009
  20. SeanDezart

    Z Club Member
    Official Trader

    He said after having a very nicely sorted L-gata removed........:rolleyes:

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