Louvers on the Decklid?

[greggearhead]

Don't have my R-Rs-RSR book yet, so will have to be the annoying newbie.

Were there any 911s raced with extra louvers in the decklid? Just curious.

Thanks.

[kenikh]

I've never seen it. I think it is a VW thing, like decklid standoff hinges, etc, in pursuit of extra cooling. Wasn't needed on the 911.

[John Z Goriup]

You won't find any photos or stories about 911s with additional louvres in the engine lid in Starkey's book......in fact I can say with a fair degree of certainty that no book about 911s I have ever seen or read had any mention or pictorial evidence of louvers in the lid of any 911.

I have seen a couple of hot rod 911s with additional louvers cut into their lids but they were strictly backyard projects for looks only. 911s, when built sensibly and correctly simply do not require additional open area for more air (whether it's for cooling or for combustion). Just think of the number of 3.0, 3.2, 3.6 and even 3.8 liter engines in early chassis with stock lids that are running around.......without louvers. There are even a few Torbos ( albeit without intercoolers) and they work fine. In fact, I'd recommend thinking long and hard about cutting louvers: without knowing or having the information to accuarately calculate the required cfm of cooling / intake air for your specific engine set-up, how can you be sure that you wouldn't disturb the airflow required and actually reduce efficiency.

What purpose do you want the louvers to serve, and what makes you think you need them.....( other than looks)?

1. are you experiencing elevated oil temepratures, is your engine overheating ?

2. Is your engine starving for air ? What's the evidence, if any ?

3. Are you planning to have the louvers face forward or open to the rear ?

4. Is there a ducktail on your car ? That would introduce another set of questions altogether.

The engine compartment of a 911 is designed to be a virtually sealed cavity, forcing the available air through the (correctly sized) fan so that air can be delivered where needed at the designed rate to take away heat, the rest of it goes into the carburetors or injection to support combustion. This entire assembly was designed as a package, with the size of the opening in the lid, the fan, fan RPM, shroud, cylinder & head fins and the engine metal hardware / ducting and sealing rubber all interacting. (Turbos with intercoolers are an entirely different kettle of fish and should not be part of this discussion)

I respectfully submit that we need to give the engineers who came up with the 911 and subsequently developed it into a unique and extremely effective device much more credit that they indeed knew exactly what they were doing. There may be areas where hot-rodding and making cosmetic changes is perfectly acceptable and occasionally may even results in an improvement, but again, with all respect, I submit that the matter of airflow to the engine should not be one of the areas subject to indiscriminate alteration.

No offense intended, just a reminder that function must always come first, with looks and cosmetics playing supporting roles. Having delivered myself of a lenghty, unsolicited opinion, I am attaching the only photo if have ever seen of a 911 with a louvered lid. I did not take it, I don't know anything about the car or how well is works ( or doesn't), I am just posting it for your review.

Regards

JZG

[greggearhead]

That's exactly why I asked. The engine isn't even running yet, but I am just toying around with ideas for performance and cosmetics. The louvers was just an idea for mainly cosmetics, but the last thing I want to do is something to *sacrifice* performance (and in most instances reliability).

Appreciate your input - not saying I wouldn't do it, but would at least play around with temp probes, manometers and tufts of yarn first!

[letsrollbabe]

Here is another solution to get heat out of the back end, and it provides a 'cool' look. I would sell this if anyone is interested. The exhaust cut out areas are reinforced so that the panel can still be bolted to the bumpers with integrity.

Gib

[curtisaa]

Hi Gib...where did you get that ? I have one of those that has a factory part # on it. I bought it like 10 years ago and now it's on my 1970 911S. That is how many of Vasak Polak racing cars were done. One small difference is that mine only has a left side cut-out for the exhaust.

[72targa]

Long ago and far away, I had a 1982 Chevy Silverado P/U that I customized with a hood that looked like this. Amazingly, I never took a picture of it. Wish I still had it...

[letsrollbabe]

Hi Gib...where did you get that ? I have one of those that has a factory part # on it. I bought it like 10 years ago and now it's on my 1970 911S. That is how many of Vasak Polak racing cars were done. One small difference is that mine only has a left side cut-out for the exhaust.

Curt:

I looked at the back and can't find a P/N...where did you find it? The louvers are very uniformly done...not individually cut for sure, had to be an original stamping when the panel was made. They are perfectly centered and all dimensions and clearances are very consistant on both sides. But I have never seen a picture with one installed...do you have a shot of one on a VP car?

Gib

[boba]

Curt, Gib,

I have seen a few of the licence plate panels with louvers and in every case the owners have had them cut. So no conformation of factory parts. The stated reason was to vent heat from the muffler, none of the owners had any hard numbers of reduced temps but it made them feel like they had accomplished something.

One owner had paint blister on his LPP so this was done prior to repaint and he no longer had burnt paint.

And it did look cool.

[MarkS]

Any old time hot rod shop can do the louvers uniformly. I did this 10++ years ago and it increased top MPH at the end of a 110 MPH straight 2 MPH. I can only guess it may also rear reduce lift.