Muffler / turbo shield

[kolies]

Should there be a shield above the hot parts of the exhaust system / turbo and the bumper and the rear sheet metal. I don't have one there, and everything in the back of the car is very hot after driving, like the rear fenders, bumper, and even the license plate.

I was also thinking of cutting vent holes in the rear bumper to let some of the hot air flow out from underneath the car. I've read some threads where this was done, and it seemed to help. Any experiences with this?

Thanks

Karsten

[WinRice]

On my 1986 there's a heat shield that extends from the top of the bumper to the bottom of the valence, about the width of the rear reflector.

Not sure about your year.

[billjam]

Karsten,
Here's a few pics to ponder as an option.
I removed the heat sheild, the rubber seal between body and bumper and the rear valance. The bumper also picked up some slots behind the turbo.
It gets pretty hot here in summer so I worked on the principle of getting as much air through that area as possible, as opposed to trying to keep it in with shields and seals. Euro-style bumper rubbers helped make space for the slots and the number plate.
It works for me.

[equality72521]

Damn, Bill. You have your O2 sensor wire right there on the turbo! BTW, how did you cut the slots?

[billjam]

Mark,
The O2 wire isn't as exposed to heat as it might appear above. I made up a small sheild for it. It is also very easy to get at the sensor for recalibration. I can undo it using a spanner through the slots.
I marked out the slots on the bumper, drilled four corner holes for each slot (1/2" I think) then jig-sawed between the holes inside the lines. Final shaping with a couple of files was followed by a repaint in my carport. Don't you just love plain simple colours like GP white!

[kolies]

Bill,
I like that option a lot. You did a great job. You must notice a big difference in temperature. Thanks for sharing the pictures to the heat solution. Moving the plate off center will definitely help as well

Where did you find the Euro style bumperettes? It would be great to get the big ones off the car.

Cheers,

Karsten

[equality72521]

Nice work Bill. I though you had a machine shop do the work. Very nice.

[billjam]

Originally Posted by kolies

Bill,
Where did you find the Euro style bumperettes?

Right here - PP Porsche 911 Used Parts For Sale & Wanted

[equality72521]

That bottom bolt looks like a *****!

[billjam]

Originally Posted by equality72521

That bottom bolt looks like a *****!

You guys don't miss much, do you!

When I replaced the 3LDZ with a 7200 type, it pushed the muffler about 15mm to the right which made it hit the body (top right of muffler in first pic above).
To get some clearance back, I had to cut 15mm out of the the muffler inlet pipe (note the weld). Then to get proper access to that bottom bolt, I had to sacrifice half a horsepower and put a dent in the pipe.

[Mark Mcgarry]

My bumper ...idea from another Pelican.

[hoyabear]

Billjam,

Any data on temperature reductions as a result of your mods (oil temp or otherwise)?

[billjam]

I didn't notice any difference to engine operating temps. No data.
I recall that I was having a problem with coking of oil for a while. I fixed that by changing oil type, but as a bit more insurance, I decided to get more airflow around the turbo as well.

[kolies]

Bill,
With the slots cut into the bumper and the other changes that made, how much of a difference in temperature did you see on the rear fenders, bumper,...?

Karsten

[Highway-Star]

hello, I have put some 30 meters (+30 yards) of exhaust wrapping around the exhaust.
- in between layers I have put aluminium foil, same stuff people use in cooking around kitchen.
- one does need to remove the exhaust for adding the wrapping... without removing I don't think it is going to work.

Rear bumper... I have put aluminium foil in layers to the side facing exhaust. (needs bumper removal ideally) Glued together with polyurethane foam. Polyurethane perhaps is not the best for really hot places, however seems to work fine for me (not burning). Air is a good insulator, anything that keeps the aluminium layers detached, and does not burn, and glues aluminium foil, should be ok. Polyurethane expands quite a lot after applying, I did not put that much between layers, and kept pressing with hands so that there is perhaps only 1-2mm between aluminium foil layers. On a hot weather (in Finland), at nearly 90 degrees Fahrenheit, the rear bumper feels warm like it has been taking sun, but it is not hot.

My reasoning has been, there is "industrial scale" energy coming from exhaust, maybe it is just best to insulate and lead heat out from the tip of the exhaust, rather than ventilation.

Perhaps ventilation is a good an idea, just wrote these thoughts, in case someone does not want to cut rear bumper.

Greetings from hot Finland, around 90F (30C) (hottest for decades this summer)

[A930Rocket]

Even without a valance, mine has gotten hot enough that I thought I get 3rd degree burns touching the bumper after a track session. It melted the left bumperete to the point it was melting and dripping. That's when I threw them away and went bare bones back there.

I'd try the slotting, but I'm afraid it was look like Fido's a$$ when I finished it...

[billjam]

Originally Posted by kolies

Bill,
With the slots cut into the bumper and the other changes that made, how much of a difference in temperature did you see on the rear fenders, bumper,...?

Karsten

Karsten,
I don't think my mods made much difference to rear bumper temperature one way or the other. My sole aim was to get heat out of the area around the turbo, so I wasn't really concerned about bumper temp.
It does get hot, and I certainly wouldn't sit on it, but it is not that hot that it causes any problems or paint burning.

[bkreigsr]

with all the slots, the temp of the bumper itself came down about 120 deg, the exhaust came down about 200 deg, and the oil came down about 40 deg. (after a session of spirited use) - I used a cheapo laser temp gauge from Northern Tool.
that area holds a significant amount of heat in the absence of any ventilation.

I'm of the opinion (I could be wrong) that any kind of wrap or foil will only increase the exhaust temp by keeping all the heat in, and decrease the efficiency of the turbo. - especially if you have no intercooler, like NO RSR.
Bill K

[hoyabear]

Bill,

Interesting to see that all of those slots have reduced oil temps as much as 40 deg! I like the look of the stock rear, but I am definetly considering going towards some kind of slotted/vented bumper now.

I'm installing a fan on the carrera cooler this weekend (hopefully), we'll see how much that helps with the temps on my car (runs really hot ~ 250+ on a hot day), I might have to start poking holes!

[Miguel Antonett]

Clever ideas!