jdogporsche

So I have a quick couple of questions. I need to replace the airbox in my 77 911 and have priced out the air box on Pelican $484.25. I have also seen an air box on Fabspeed for $175. Supposedly high performance with the following.

-800% more air volume through the air box and filter.
-This is the only high performance air box available for these 1974-1983 911s.
-There are now two large openings of 5.4" x 2.4" for maximum airflow.
-Rain cannot come in. Side entry airflow like a covered bridge.
-Very hi-tech carbon fiber look for your 911 engine bay.
-Simple and easy installation in 5 minutes. No other company offers a high performance air intake for these cars. This system might also save your engine airbox from backfires.

My question is if it is a good idea to go with something like the high performance airbox or to go with the OEM box from Pelican? Also, any idea on if the Fabspeed air box has everything I need to replace my air box or if I will need anything additional?

My other question is this...my car came factory ordered straight from Germany and even though it is a 77 911, it has a Euro 3.0 (yes, this is how the car came from the factory). So would I need to get the CIS Air Box (44mm Intake Port) or the CIS Air Box (38mm Intake Port)?

Thanks in advance!

Jeremy

jdogporsche

Well I have an answer to some of my question. Just spoke with Fabspeed and they said that the air box that they have is all that I would need. They said that since it allows more air flow the risk of backfires is less as well, which should help prevent air box cracking of course. Another question though. How hard is it to remove the old air box?

theiceman

oh no here we go again !!!!

some guys say you need to take the engine out, others say it can be done with the engine in. Quick do a search before the debate starts...

jdogporsche

Well, I have taken your advice and have read some of the arguments on removing the engine when putting on the new air box. I am fine with that. I do still have a question though on what air box is better to get, the Fabspeed or the OEM? The Fabspeed is cheaper, allows more air flow, etc, but I want to make sure whatever I get lasts. Any advice?

Jeremy
77 911 Targa, 3.0 Euro

psalt

Jeremy,

I think you are comparing apples and oranges. The Fabspeed item is an air filter cover, not a replacement for the OEM airbox, which is the intake manifold.

Paul

jdogporsche

Hey Paul,

Well I asked if this is the entire replacement for the air box and Fabspeed says that it is. Not just a air filter cover. Are we looking at the same thing or am I being misguided from Fabspeed? It is on this page http://www.fabspeed.com/911Carrera.html and is the second and third item from the bottom. In the description it even says high performance air intake.

Jeremy
1977 911 Targa, 3.0 Euro

Jay H

I would suspect these Fabspeed things are only air box covers. "Simple installation in less than 5 minutes" is my clue that they might only be covers.

You most likely need the entire air box from Porsche or Pelican or another Rennlist sponsor.

I've read for many years that Porsche didn't leave much on the table in regards to air box intake volumes until the 964 model. It's been my belief that modifying the SC or 3.2 Carrera air box gives little, if any gain on a street driven, fully stock car. Pulling hot air from the engine compartment via a cut up air box cover might reduce power verses a plain ol' stock air box cover.

The snorkel on the 3.2 air box does the best job of pulling cold air in from the outside of the car verses these modified boxes. I would assume that big snorkel on the SC air box is doing it's job too with pulling cool air from the deck lid grill verses pulling warmed air from inside the engine compartment.

The 964 Cup Cars did have modified air box covers from the factory and then only minute gains (1-2 hp??) were noted by the factory.

Peter Zimmermann

Well, I was going to tread lightly regarding this thread, but... "5 minute installation" makes it impossible to be anything other than the filter cover, which Paul has correctly pointed out. Now, about air flow. I'm confused as to why that matters, the air still has to pass through the sensor plate housing and throttle body, and they remain the same size orifices. Somebody has to explain why this part qualifies as "high performance." Regarding the statement that the "airbox" MIGHT save the engine from backfires is just plain bizarre. Everything that causes blown airboxes has nothing to do with the filter or it's cover, and this part isn't going to change that. Order a factory o.e. airbox, intake runner sleeves, throttle body o-ring, injector o-rings & sleeves, etc., pull the engine and do the replacement. Be aware that following the job the CO% must be set to factory spec!
Pete

jdogporsche

Ok well that does help shed some light on it and I do appreciate your feedback Peter and Paul. So I will go with the OEM Air Box. From some of the other threads I did searches on, it looks like this job with the part runs about $1200.00 and I will also want to get the following replaced right?

(1) the throttle lever bell crank bushings on top of the engine, and
(2) the crankcase breather hose (to the crankcase).

I am also going to get a new air filter, fuel filter, oil filter and oil as well as new wires, cap & rotor, along with new plugs.

The car has been sitting for 6 years so I figure all of these things can't hurt.

One last thing. I know Peter that you have said that you don't recommend the Pop Off Valve, as a good running engine should not need it, but isn't it worth the money to possibly prevent having to spend $1200 again if something were to go wrong? I am not trying to start an old thread back up, just wanted your two cents specifically Peter.

Thanks!

Peter Zimmermann

Jeremy: First, I will assume that you're going to contract a shop to do the work. If that's the case you will want to be sure that they do the breather hose and bell crank bushings (both a very good thing) and that you want the oil pressure warning light switch and thermostat o-ring replaced. Now, regarding the pop-off valve. Ask them straight up if they know how to set cold control pressure, and if they can set yours to the rich side of the acceptable range (when this is done you will get a subtle cold start surge that can last a couple of seconds to more than half a minute depending on ambient temp) as part of the job. Replacement airboxes are fitted with a fuel diffuser that is mounted inside the manifold chamber of the box, and it directs cold start fuel spray directly into the six intake runners, rather than allowing it to collect in the chamber. Basically this fixes the blown airbox problem. I personally would never put a pop-off valve on my own SC (my first airbox lasted 192K miles), and I never put one on a customer car. Other than the few exceptions that I've posted in the past I just don't believe in them.
Pete

flatsixnut

Fabspeed is a sponsor. I would love to hear their explanation.

Naitove

In the interest of truthfulness in advertising, no one has pointed out that it does say in the description " This system might also save your engine airbox from backfires."

Obviously, it is not meant to replace it.

jdogporsche

Yeah Naitove, I noticed that today as well. Yet, I asked specifically...if my air box is cracked, will this replace it completely or is there anything else that I would need to get. The tech I spoke with said, "Nope, this is all you need. You take the old cracked air box off and put this one on." I then replied, "Wow, that is great. I thought I would have to buy the new OEM air box that costs around $480" to which he replied, "Yep, it's a great deal on a great Air Box."

I am not putting Fabspeed down, perhaps we got our lines of communication crossed somehow, but it is apparent to me now that it is not the product that I am looking for. I will be going OEM, bringing it to a shop and having them change it out along with many other things.

Here is a question. If I am getting the Air Box replaced, the throttle lever bell crank bushings on top of the engine, the crankcase breather hose (to the crankcase), a new air filter, fuel filter, oil filter and oil as well as new wires, cap & rotor, along with new plugs, intake runner sleeves, throttle body o-ring, injector o-rings & sleeves and last but not least a new battery.... how much am I looking at spending? Anyone know? Just a rough guesstimate. Trying to prepare the wife :-) I was thinking around $2000-$2500.

Thanks all!

theiceman

I guess they try to differenciate air box from " engine airbox"

Peter Zimmermann

Jeremy: You're in the ball park on price - most of the items that you listed are part of the airbox replacement. I don't want to step on toes, but please permit me a couple of comments...
1. Skip trying to save a few bucks by buying an airbox, you will make your shop very happy if you allow them the small profit on the part. Who knows, they might even do that thermostat o-ring at no charge!
2. Remove the old battery and prep the battery compartment thoroughly before towing the car to the shop, even a little painting if necessary - they will love you!

Also, as an afterthought - give that engine compartment sound pad a good look. Plan on having the shop replace it, if its ugly or missing, while the engine is out, it'll be a nice touch.
Pete