under hood airflow

[seniorchristo]

I read somewhere recently where due to the Elan's body shape, there can be a large build up of air pressure under the hood resulting in front end lift at high speeds. I've also seen some Elan under hood pictures with holes cut in the body on certain cars to relieve this air pressure. Most notably Jay Leno's green Elan has some round holes cut near the cowl at the base of the windshield. I also remember seeing a car with holes in the inner fender wells. What is the general thought regarding this at speeds up to around 80-100 mph. I'm not really interested in cutting up my car but I'm curious to know what other's think.
Later,
Chris

[john.p.clegg]

Isn't there a big hole at the bottom of the engine bay?..surely enoughto let all the hot air out?? Lets enough oil out anyway....

John

[Europatc]

I think you will be safe Chris
all the best
Stuart

[seniorchristo]

Let me rephrase the question. For speeds of 80-100mph, do you think it would make a noticeable difference if the under hood air pressure was reduced or eliminated?
Thanks,
Chris

[rgh0]

I get no "noticeable" front end lift up to 120 mph / 200 kmh on the track. There may be some, but it does not affect the handling or stability in any significant way

cheers
Rohan

[gherlt]

>I get no "noticeable" front end lift up to 120 mph / 200 kmh
and beyond that ???

Returning to reality ... I made two holes for getting more hot air out, especially the zone of carburators and petrol lines (car is used for rallying in Spain).

[jensmartin]

Isn' t a matter of low pressure area above the hood creating the lift? As a wing profile?

/Jens

[trw99]

Chris, have a look at this thread: lotus-chassis-f36/paint-layers-t26995.html

Tim

[rgh0]

>I get no "noticeable" front end lift up to 120 mph / 200 kmh
and beyond that ???

.

The longest straight I race on is at Phillip Island and can hit 200 kmh with no wind before the braking zone for the 150 kmh right hander . With a strong tail wind I can get to maybe 220 kmh at which point I am doing about 9000 rpm in top and I call it enough

If you have an issue with loss of steering feel at high speed in an Elan ( FHC at least) then something else is probably wrong with your set up.

cheers
Rohan

[el-saturn]

i remember seeing a pretty big hole to the left of someones collector - leading to the left wheel well (mesh covered) - however and most probably to get some hot air out of the engine bay and not to improve aerodynamics --- sandy

[mbell]

however and most probably to get some hot air out of the engine bay and not to improve aerodynamics --- sandy

My understanding is the same as Sandy's. The main purpose of the holes in the inner wings with mesh cover is to provide and escape route for hot air trap under the bonnet/hood.This is reported to help reduce engine temperature on higher speed cruises and when stationary I think.

[Sea Ranch]

As Tim suggested, check out that thread on paint layers. The discussion turns to holes in the engine bay and someone has kindly added bits from a Lotus bulletin detailing the purpose of said holes. They're for heat extraction, on the exhaust side.

Check it out.

Randy