The Cal-look Lounge

Cal-look/High Performance => Technical stuff => Topic started by: george4888 on December 03, 2019, 12:04:42 pm



Title: Deck lid grills and what they do ?
Post by: george4888 on December 03, 2019, 12:04:42 pm
Do the deck lid grilles on the 1972 Beetle suck in cool air or let hot air out ?  I always thought VW added them to let in more cool air to the engine but someone told me the hot air from the engine compartment is exhausted through the deck lid stock vents ?  Seems to me they only bring in more cool air for the larger engines and larger cooling fan ? What is the air flow going to them, either it sucks in or exhaust hot air ? What is the verdict on this ?  Thanks.


Title: Re: Deck lid grills and what they do ?
Post by: mikko k on December 03, 2019, 12:14:07 pm
Hot air goes under the car. Grills gets more cool air. And that is why you should use all tin in engine, to separate hot and cool air.


Title: Re: Deck lid grills and what they do ?
Post by: Martin S. on December 04, 2019, 00:10:03 am
There’s plenty of heat coming out the vents with the turbo under there. But only after I stop. I used to prop the engine lid open to let it out when I got home. Now I have the Jason707 retractable decklid hinges and love how the heat can escape easily when I park.


Title: Re: Deck lid grills and what they do ?
Post by: WhiteTrash on December 04, 2019, 19:01:27 pm
Do the deck lid grilles on the 1972 Beetle suck in cool air or let hot air out ?  I always thought VW added them to let in more cool air to the engine but someone told me the hot air from the engine compartment is exhausted through the deck lid stock vents ?  Seems to me they only bring in more cool air for the larger engines and larger cooling fan ? What is the air flow going to them, either it sucks in or exhaust hot air ? What is the verdict on this ?  Thanks.

As Mikko K said above, the vents help to get more cool air into the engine bay for the fan to suck it in and blow it out below the engine (and through the heat exchangers if you have a stock exhaust system.
That's the reason why cabrios had them in the engine lids first. They have no air vents below the rear window so need to get the air from somewhere.


Title: Re: Deck lid grills and what they do ?
Post by: Neil Davies on December 04, 2019, 19:23:59 pm
Think about a cabriolet - they have vents in the decklid because they don't have the vents under the rear window. It's the only way to get air into the engine bay.
Adding vents to an already vented system simply allows more air in to bigger carbs and a fan turning at higher rpm. As Mikko says, there should be no hot air that side of the tinwear.

Edit: dammit Frank, I stop for a McDonald's and you go and beat my post!


Title: Re: Deck lid grills and what they do ?
Post by: Martin S. on December 04, 2019, 23:44:15 pm
Unless there's heat coming OUT of those vents, your car is too slow!  :o


Title: Re: Deck lid grills and what they do ?
Post by: JeeWee on December 05, 2019, 19:14:40 pm
There’s plenty of heat coming out the vents with the turbo under there. But only after I stop. I used to prop the engine lid open to let it out when I got home. Now I have the Jason707 retractable decklid hinges and love how the heat can escape easily when I park.

Hi Martin, do you have a picture of the 'Jason707 retractable decklid hinges'? Where are they available?

Thanks in advance!


Title: Re: Deck lid grills and what they do ?
Post by: Martin S. on December 05, 2019, 19:34:16 pm
Everyone needs these. The only downside is that the spring can’t be used anymore.

https://youtu.be/jjRQb97zrTQ