Full undertray ? | Page 2 | 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

    Thanks - are those cut-outs for the sump pan and exhaust manifold ? And angled upwards from the engine to allow space for the steering rack etc ? I was thinking it would have to be cut out each side there too......
  2. twoforty

    twoforty Well-Known Forum User

    I would havve thought a decent front spoiler would help sort the front out, its the rear valance acting as a scoop that I'd like to sort out.
  3. SeanDezart

    Z Club Member
    Official Trader

    Valid points Ben and ones that make one weigh up if it's worth it but as I think it is.......I shall continue.

    Yes, I too am afraid that it might lighten the front end at speed which is what I was used to in my previous Z. Mine now suffers much less and I'm considering a front spoiler (I've bought and rejected a few already) to combat any ill effects.

    The other thought is that as air might be running under the car faster than above it would creat a 'ground-effect', actually 'sucking' the car into the track......no ?

    Rob - funnily, I don't have any brake problems :p and no cooling ones either but if it's an advantage, I won't begrudge it and who knows if I don't mod the engine some more revs.......
  4. Sylv1

    Sylv1 Well-Known Forum User

    take care to carb air induction :rofl:
  5. SeanDezart

    Z Club Member
    Official Trader

    It won't be as tight as a wetskin ! Besides, I can always fit one of those leaky airboxes......

    Count - did (does) the PZ-R tray fit up until the rad. support panel or go all the way up 'til the front skirt ?
  6. Rob Gaskin

    Rob Gaskin Treasurer Staff Member Moderator

  7. grolls

    grolls Well-Known Forum User

    Nope your missing the point, a well enginerred and tested spoiler will aid air flow over and under the car, im talking getting hot air away from the engine bay.....althogh we may be at cross purposes ....lol
  8. twoforty

    twoforty Well-Known Forum User

    Ok lets call it an Air dam instead of a front spoiler....if it's rigid enough and designed in a way to push air to each side instead of under the car it should help with underside aerodynamics, it should also restrict lift.
  9. SeanDezart

    Z Club Member
    Official Trader

    I don't want to see the thread develop into a spoiler this, airdam that BUT I do see that an undertray might benefit from something extra at the front.

    Is an S30 really going to have air pushed over the car considering the aerodynamics at the front, bonnet overhang, bumper, huge gap for the radiator........?

    For info, a Renault Laguna MKIII with an undertray is - 0.2 drag coeff. with one as opposed to being without - that's not inconsiderable !

    Rob - brakes slow you down........:driving:

    Grolls - this is what I'm thinking about more efficient cooling and I don't like the idea of the current airflow through a fussy engine bay and hitting the baulkhead head-on !
  10. grolls

    grolls Well-Known Forum User

    Thats why you need that "suck effect" lol.....:eek:
  11. Sylv1

    Sylv1 Well-Known Forum User

    Yes, full undertray on Lag-III let get minus 0.2L/100km compared to classic simple engine bay undertray... kind of things very usefull to match to120g CO2 taxes!
    My Z have nothing at all... so I can imagine that would be more usefull.

    OK gas milage is not the purpose but Vmax for the Hunaudires :driving:

    In parallel, I don't expect and don't want ground effect because it is another range of engineering that I cannot afford... just a bit SCx for me !
    Danger is to upgrade underhood temperature... but thanks to Skiddel magic box, that is not a problem for me :thumbs:

    I was imagining alloy panel fitted like Albrech shared with us about Z432
    Next step is the rear axle ;)
  12. Rob Gaskin

    Rob Gaskin Treasurer Staff Member Moderator

    Joking apart re brakes, you must consider what else the air under the car does. So don't restrict brake, gearbox, diff cooling. On short runs it may be ok but on a trip across France things MIGHT get too hot. Just a thought.

    From a practical viewpoint I would find an undertray a pain in the arse (no I don't sit that low) when working on the car and it would catch on my drive.
  13. SeanDezart

    Z Club Member
    Official Trader

    Ok :

    brake cooling (helps to have 'open' wheels) - needs to be looked at from underneath the car but either a less large tray or ducts but ventilated discs are an enormous advantage already.

    Gearbox - the tray wouldn't cover that so I don't see any negative effect.

    Diff - ditto but if really necessary, a diff cooler ?
    A tray would (I think) increase air-flow underneath so cooling of these parts should be likewise increased - no ?

    And as the airflow is increased underneath the car (Grolls' suck-effect), so the car is held down. It's the complete opposite of the way an aeroplanes' wing works.

    This idea can actually use the S30s poor drag coeff. in it's favour and probably even aid braking and avoid understeer.

    I don't see that it should be a hindrance to work on a car as it attached with the right equipment, it could be detached in less than 2 minutes. It shouldn't have to be lower than the sump pan and I don't know about yours but my middles section exhaust pipe is VERY low already....a small secondary effect of a tray might be as that of a skid to avoid unpleasant 'knocks' against low cement gate-post holders, curbs etc.

    I'm going to see about having something fitted this winter in metal after a thorough examination of my Z on a ramp. Will keep you posted and in the meantime any and all reflections on the subject are VERY welcome.
  14. grolls

    grolls Well-Known Forum User

    Metal? wtf! your engine will never pull the car up a driveway as it is. Why not make a template and make it from fibreglass or even better carbon....it aint hard!
  15. GZ32

    GZ32 Well-Known Forum User

    Completely agree, Did this to a spitfire years ago with some thin ply, car went over a bump at about 40 and tried to backflip. Needless to say, it came strait off.

  16. SeanDezart

    Z Club Member
    Official Trader

    Perhaps Spitfires are more aerodynamic than a Z and therefore more air passes quicker over than under.........?
  17. grolls

    grolls Well-Known Forum User

    The question is, did you go over the same bump at the same speed to check? Ply and steel is not a good idea as it has no flex, I would use a composite or plastic. One can only try it and see. I would still go on the forums in Japan or where else that under tray was sold to seek information. Perhaps the count could tell us when that pic was created or for what year of car and why it never went in to full production on other 240/260 ....oops, gr30 grs30..;)
  18. GZ32

    GZ32 Well-Known Forum User

    I took it off, hit the same corner without it and it stayed on teh ground. I was going to put the car up to full chat, but it was so unstable at low speeds there was no point.

    I have since learned that you need to create a negative preasure beween teh wheel to suck the car down more and funnel teh air around absticles so it flows out the rear easily.

    Not as easy as it seems, you need a smoke device and a fan to see if it works. All in all, you can make things a lot worse for a lot of effort.
  19. Rob Gaskin

    Rob Gaskin Treasurer Staff Member Moderator

    I was at Mallory Park on Sunday with my lad MotoXing but managed to watch a few circuit races too. Even the MG Midget/Sprites were using ground effect with diffusers instead of a boot floor! - full race cars of course not road cars.
  20. grolls

    grolls Well-Known Forum User

    I think Shaun has to go back to the counts post and ask ;

    Why was the tray developed?
    Why was it not used on other cars?

    Was is cost?
    Did it cause instability?
    Are they still available?
    Did it aid cooling etc?

    Good luck in your search Sean....:)

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