After only 3 years of project work, I realized that I am missing the lower-most engine sheet metal parts on both sides. These are the horizontal pieces that sit even with the heat exchangers. How important are these? Any advantage in not having them?

You want them. They help with engine air flow. They aren't expensive and can be installed easily.

AA has them

Hate to say it Bob, but the boys wanted these for good reason. You can probably run without them, but cheap insurance to have them in place.

How is she running?

I have a NOS one. I'll check the part number on it later today. I think I paid $10 for it. You can have it for $10 plus shipping.

Make sure you get the right ones for your car.

The driver side has 3 different versions depending on the exhaust and transaxle shifter on the car.

Tail shifter + 70-74 exhaust. Plate goes under the shift linkage.
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Side Shifter + 70-74 exhaust. Plate goes Over the shift linkage.
This seems to be the most sought after version as early cars are converted to side shifters and late cars are converted to early exhaust.
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The passenger side only has two versions based on the exhaust 70-74 and 75-76.

There are some parts posted on vendor sites with the incorrect image per the description. First I ordered the wrong part and with my second order of the correct part the vendor sent the wrong part per the description but promptly sent the correct part once I showed the images/description from their site.
Point being the subtle difference between over/under the shifter is easy to mix up.

Running pretty good. I have a dyno session planned for next week to dial in the Megasquirt EFI tune.

Thanks, everyone. My '73 has a side shifter and "normal" exhaust. If anyone can confirm the correct part numbers, I will be eternally grateful. Or at least for a week.

Thanks, and happy to take you up on that if we can confirm the right part. BTW, which side?

Should be these, but check the images and descriptions when you buy them.

73-74 Driver side: 022 119 356 A

70-74 Passenger side: 022 119 355

When you run headers you loose the provisions to mount them, and I have run that way for 20+ years.


But if you are running stock heat exchangers you might as well run them. The Germans were not generally known for adding extra parts for no reason.

They also connect the HEs to the case. Stiffens things up. With these, not dependent on the exhaust stud nuts and rear hanger to keep the HEs secure. Extra layer of protection of the push rod tubes.

so necessary that we spent a lot of money to tool these, besides protecting the cables from the heat, they direct cooling air towards the engine.

Yep, Porsche wasted a lot of money on parts that the cars DID NOT need.

yes and no.

i agree with dr. 914. they stop the cables getting roasted.
or at least that portion of the cables.

i think they were an attempt by porsche to try and get the spent cooling air from out under the car by trying to squirt it towards the rear.
conventional rear engined VWs did not have the problem.
the heated air did not pool under the car, its just squirted straight out near the bumper and into the open air.

the hot air pools under the 914 and gets trapped - when the car is at standstill.
with the warm air guides it pools under the trunk and gets trapped in a big bubble there.
without the guides it can pool up in the front section and add to the original fuel pump vaporization woes, though to some extent that is also due to the air exiting the heat exhanger valves there.

all in all, my honest view is it was an attempt to solve a problem that they never really fully solved? the engine being so central in the car.

with the car on the move its academic whether you have them or not.
except to preserve the clutch cable and speedo cable.
which you can also do with an insulation wrap.

the important guides are the ones higher up the direct air around the cylinders and fitted closer to the cooling fins.

but there is nothing wrong with being a purist and having it all set up factory perfect.

i have not had a set on mine for 30+ years.
but now that dr. 914 is making that hard to get one as a reproduction i might just get a set now and fit them.

will report on whether it really does make any difference when stuck in traffic.
in australia.
somehow i doubt it.

I thought there was a part number sticker on it, but I guess not, so I'm not sure if this is correct. Click to view attachment
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I little bit of history about the sheet metal in question. At the time the 914 was being developed, pizza became a big hit in Germany. The Porsche design department, lead by Dr.Ing Otto Pepperoni, thought they could expand the market for the 914 as a pizza delivery vehicle.
Thus, these sheet metal additions were made to pool hot air under the trunk. The trunk was now nice and toasty allowing your pizza to arrive piping hot. The Pizza Porsche ad campaign was dropped when it was found that all pizzas arrived tasting the same-they all tasted of car exhaust;)

On type 4 powered vw bus the equivalent part is like this



Besides directing hot air out the back of the car, they also protect the pushrod tubes and the thermostat which are soft metal from stones etc. If you get a hole in a pushrod tube, you would lose a lot of oil very quickly.

@nathanxnathan . good point re thermo. never thought of that.
would also even up the air around the thermo.

now that makes sense to me as the reason for them.

more likely protecting pushrod tubes from being dented.
and causing a pushrod to be interfered with (oil flow) rather than be punctured.
another good reason making sense.

914/6s and 911s don't have lower air guides. they just blow it straight down.
no pushrods. (maybe oil return tubes, can't remember?). no heath robinson cooling flap gizmo/thermo.

i'm guessing 356s have the guides.

I'll match it up under the car tomorrow, but I believe it's the driver's side.

Thanks.

Yep,. It's the driver's side.

Hello....I have SS heat exchangers....SSI I believe...do I still have the mounting screw holes to mount these heat shields?
Thank you,
gg

Mine do. I have no idea specifically what the source of my SS exchangers was. They were on the car when I bought it in 82 or 83.

Sent you a PM.