Full undertray ?

SeanDezart

SeanDezart

Well-Known Forum User
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 ?
 
johnymd

johnymd

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.
 
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.
 
SeanDezart

SeanDezart

Well-Known Forum User
grolls said:
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.
Click to expand...

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.....
 
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2

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.

Chris
 
Albrecht

Albrecht

Well-Known Forum User
SeanDezart said:
.......served to pass air underneath....
Click to expand...

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......
 
grolls

grolls

Well-Known Forum User
SeanDezart said:
So 1/3 air intake and 2/3 exit ? Not sure that I follow correctly here Paul......:unsure:

quote]


Yea after re-reading I see your point, so here we go again..... you should have 3 times exit volume to intake volume. This cause's an "air suck effect" out the back. All modern cars have full undertrays.....have you never wonderd why?
Click to expand...
 
SeanDezart

SeanDezart

Well-Known Forum User
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 ?
 
Albrecht

Albrecht

Well-Known Forum User
SeanDezart said:
Pretty please may I see a photo of said........
Click to expand...

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:
 

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Rob Gaskin

Rob Gaskin

Treasurer
Staff member
Site Administrator
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.
 
SeanDezart

SeanDezart

Well-Known Forum User
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.
 
ben240z

ben240z

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
 
grolls

grolls

Well-Known Forum User
SeanDezart said:
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 ?
Click to expand...



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?
 
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
 
Rob Gaskin

Rob Gaskin

Treasurer
Staff member
Site Administrator
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.
 
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