So above the VIN stamp, in that slim area there? There's not much blocking air up there. The question is, what's on the cowl grille side? Is it filled with wiper motor mechanisms and so on? I've never removed mine to look.

 

Hi Vancouver

I do exactly the same as you and take the Rain Tubes off because I never go out in the Rain and even with the unmodified Windscreen Wiper Pod

A lot of Heat from the Engine Bay seems to spill out of there, which really helps to keep the Engine Cool

Not sure about Fumes from the Engine Bay but since I only go out when the Weather is Sunny enough for driving with the Top Down, I haven't really noticed any fumes

As such I would imagine that a modified Windscreen Wiper Pod with a wider opening, just like you described would make an Amazing difference to the Heat Extraction from the Engine Bay

Without those Bonnet/Hood Louvres which look great on an XKE but not so much on an XJS but having said that I don't really want to go hacking my Cars around with an Angle Grinder

Though having a Pro Body Shop modify that Wiper Pod could be a good idea

Thoughts Guys?



When I took the Tubes off the Rain Ducts, a lot of Heat Spills of the Windscreen Wiper Pod but since this Car is a Convertible that I only drive with the Top down, I can't say that I've noticed any fumes from the Engine Bay

Although I wouldn't want to risk it in a Coupe! (Don't try this at home!)

Does anyone have any comments about the Danger of Fumes getting into the Car or am I just being Paranoid as usual?

 

I've driven my coupé with the bonnet cracked open, and nothing out of the ordinary detected.
That said, I'd never remove the rain guards, as (a) I'll drive in rain if I need to or want to, especially as I live in one of the wettest parts of the country, and (b) I still have to park her outside.

 

Hi Someday

The difference is that with the Bonnet/Hood Cracked open, Fumes cannot get in the Cabin but if you pull the Rain Tubes off then the Fumes probably can

Does anyone know?

Should I put the Rain Tubes back on the Car?

 

Ah, you're probably talking about something different. Never mind--getting confused here.

 

Hmm. Might not work out that well after all. There's not a lot of room there. Not sure how you could connect the engine bay to the cowl grille space.

There's a lot of things running over the bulkhead at the top. Above the VIN stamp it's very thin, but a long thin slot might work.

 

Alex is referring to the drain tubes that run down the left and right side inside the engine bay.

Cracking the bonnet open when driving will cause air to enter the engine bay not the the other way around. If you put wool tuffs on the trailing edge of the bonnet they will get sucked into the engine bay.

Here is a test of a hood scoop, opening the bonnet will have the same effect.

 

Huh. Interesting. I suppose when you're at idle, it allows hot air to escape, but when you drive, it creates a slight vacuum and pulls air in.
Okay, I can picture the inner drain tubes. Definitely don't want to remove those in my car....

 

If you remove from the bodywork the rubber seal that seals onto on the rear bonnet edge when it is closed, in a coupe you will be semi gassed by fuel smells after a stop (eg at traffic lights) when you set off again.
On a convertible, top open, no need to worry OB!

 

Dead right, I have done this test myself. Also, about 2 or 3 years ago I experimented with holes cut in a spare bonnet - these being sufficiently far forward to ensure no inward suction. It made absolutely NO difference to under bonnet temps when on the move, at first it seemed to, but further tests showed it did not. This was to see if louvres would be worth doing.
The thing the holes DID affect was the underbonnet temperatures after a hot shutdown; temps go to nearly 90 C quite quickly in these circumstances, bonnet closed, and even more importantly, stay there for nearly an hour. With holes, or louvres no doubt, they come down in minutes. So I continued with my policy of opening the bonnet after a hot shut down!

 

i removed that rubber strip, and added this chrome piece to cover the sharp edge sticking up! it leaves about a 1/2 " gap for air flow out!

chrome strip

 

Interesting for sure, but wouldn't any increase in air flow be good? I'd imagine this is getting sucked down past the rear of the engine?

 

I have confirmed that cracking the bonnet open when temps are higher than ideal will lower them while driving. Did so going up a long slow hill last year, for example. At the time, I assumed the hot air was being sucked outside.

 

Bonnet vents just behind the radiator will aid airfow through the radiator. The high pressure across the top of the bonnet will suck air out of the engine bay. The Lancer EVO has a vent in this position.

Cracking the bonnet should in theory help cooling as cool air is being sucked into the engine bay. The reason air is sucked into the bay at the back of the bonnet is the flow travelling through the engine bay is exiting under the car, blocking air exiting the engine bay under the car can direct flow out of the back of the bonnet. New cars do this with full under trays that direct the air from the engine bay upwards which also has the effect of increasing downforce.

 

I am not entirely sure about this point Warren. As standard, with undertray and spoiler a pre facelift car has very strong downward airflow behind the radiator. When testing where to place my AJ6 intake pipes - the older type made with an extra entrance to the airbox - I placed the intakes about 1/2 and inch above the level of the undertray just behind it, fixed to the ARB pointing forwards and downwards. Then I did some air temp testing and found that, far from cold air they were intaking hot air from the rad! As a test I pointed them forward under the tray (obviously no good as a permanent place) and the temps came down to ambient.
From this I deduced that the suction under the car is pretty strong and it pulls the rad-exiting air downwards quite strongly. So whether, on an XJS, vents just aft of the rad will cause air to exit upwards I would like to test. It might be that it does enough to stall the undercar radiator-air flow and has adverse effects on high speed stability, for example.
Maybe when bored I will refit my test bonnet, cut some more holes and try it...