Potential Engine Lid modification

[MattAlpha]

Hey guys,
I was thining about doing a modification to my existing engine lid. I have a tea top ontop of a standard engine lid (three holes were drilled by the previous owner or his mechanic to attach the wing). I'm going to replace the gasket for the tail because the current gasket is slipping under the wing in a few places. I have the new gasket and I'm thinking while I'm in there, I might as well modify the lid so that I can get more air flow into the engine.

The following pic (hi-jacked from a previous post) has the two ideas that I was thinking of cutting out of the lid.
The red lines show the two areas that I'm think about cutting out leaving the center support member in there with the engine light.
The blue line area is the single piece I might cut out to get the most out of the wing's increased area.


Concerns:
After I cut the lid in the red line areas, is the lid going to vibrate? If so do you guys think I could support the center member to prevent/stop the vibrations?

If I cut out the blue line area, with it significantly weaken the lid?


So is this modification a bad idea?
I do not want to buy a turbo lid if I do not have to.

Thanks for you inputs,
Matt

[afterburn 549]

well I am a amateur enginmneer.....this is the deal, you will be unable to get any more air in there then the fan will pump no matter how big the whole is...

[MattAlpha]

afterburn 549,
thanks for the reply.

I should have stated this before. I put a K&N on the intake. Its pulling hot air from inside the engine compartment. So I figured that if I made a few more openings or widened the opening in the lid, I would be able to run an intake pipe back there so that my filter could be placed into the tea top to pull cold air in. I guess that is similiar to the turbo's intake.

-Matt

[911pcars]

My guestimate: Installing the spoiler will help add rigidity to the lid that is lost due to the planned deleted metal.

OTOH, the engine flows a lot of cooling air. At speed, the inlet air temp. will be close to ambient, that is, the same as the outside air. Is an A/C condenser going to be installed?

Sherwood

[Jack Olsen]

Are you concerned about oil temps, or horsepower?

Sherwood is correct, of course. Hot air in the engine compartment of a 911 is a persistent myth. When you're using your air-cooled engine, the intake air is effectively ambient temperature.

[RSBob]

A couple of clear plexiglass panels with round holes cut out on the top half would be very cool. Have a nice view of the motor - if its spanking clean, and get the air in too.

[MattAlpha]

To answer Jack first:
I'm more concerned about HP.
If you guys tell me that its ambient at the intake, than I believe you and I won't waste my time potential screwing up my lid.

Thank you for your advice Sherwood.

I already have the tea top installed (it came with the car as well as the other body work to make my P-car look like a turbo).

RSBob,
That would be cool to see the engine from the outside, but I'll leave that for someone else who has detailed their engine properly.

Thank you guys for your inputs. It will save me some time tomorrow not mod'ing the lid.

-Matt

[rnln]

I attemped to do the similar, leave a little edge around the exiting hole. The intention is more cool air blow to the fan/eninge and fresher air to the intake.

[kach22i]

If anything, after shut down the heat will be allowed to rise out and cool the engine more quickly.

[89911]

I don't think it is a bad idea. At the least, your taking weight away, always a good thing. It is very difficult to cut sheet metal and leave it looking like a factory part. The edges are going to rough. If your ok with this, go ahead. It most likely will look bad just from the inside.

[kach22i]

Originally posted by 89911
It is very difficult to cut sheet metal and leave it looking like a factory part.

Round holes would be easier, but I don't think it would look "factory" either.

[JBO]

I looked into this a few years ago, and the consensus seemed to be that it was a bad idea and could actually hurt airflow. Something about that extra sheet metal helps direct airflow where it needs to go, and something to do with air pressure. I ended up not doing it, and my car doesn't run hot anyway.

[widebody911]

I did that exact mod when I ran a 2.7L with a turbo tail, and the engine ran a little cooler.

Please note: this is a bad idea if you have A/C - you must force the air thru the condensor. If you do not have A/C, then cut away.

[rnln]

I wonder why it's a bad idea with AC condensor? How the turbo lid opening and tail design anyway?

[Wil Ferch]

It's a bad idea with A/c condenser because the incoming air will find the path of least resistance...and will go AROUND the condenser instead of THROUGH it ......

- Wil