987 v 986 Air box

[BYprodriver]

Originally Posted by KRAM36

Hard to tell by reading through all this, but did this end up being successful mod?

Reread if necessary! Additional post make it worse for everyone doing the right thing & searching for answers.

[KRAM36]

Originally Posted by BYprodriver

Reread if necessary! Additional post make it worse for everyone doing the right thing & searching for answers.

I've read it several times trying to figure it out. Telling me to reread it is not the answer to my question. A stock 3.2 engine with this air box. There are people with MAF issues, AFR's concerns and if done does the car need a custom tune?

[Bfan]

If we are looking at 986 S 3.2 you have two options with this airbox.
1. Saw the original MAF tube off the original airbox and plumb it ont the new airbox or

Use a MAF tube for 987 airbox that can take the original MAF and
2. a) Remap the ECU with tune from a P-car with the same diameter MAF tube and the same type of computer (i.e. 996 from the same model year for the most part but you might want to research this further) or
2. b) get a remap from some tuner with good reputation that knows what he is doing.

I myself have chosen to go with alternative 2 a) and got the so called rest of world tune from a 01 996 on my Box 01S. That way I got rid of the eternal CEL that I had for two years after catless performance header install. I first tried to move the downstream O2 sensors by lengthening the wires with thick wires to no avail, then tried so called O2 simulators but they did not work either. A good tuner would do the same but I like to be in some kind of control over what is in my car and also the original Porsche remap is much cheaper than a complete professional remap.
And there is no question about it; these engines can use the improved breathing, but I think you should do both the intake and exhaust at the same time. Hope this helps.

[KRAM36]

Originally Posted by Bfan

If we are looking at 986 S 3.2 you have two options with this airbox.
1. Saw the original MAF tube off the original airbox and plumb it ont the new airbox or

Use a MAF tube for 987 airbox that can take the original MAF and
2. a) Remap the ECU with tune from a P-car with the same diameter MAF tube and the same type of computer (i.e. 996 from the same model year for the most part but you might want to research this further) or
2. b) get a remap from some tuner with good reputation that knows what he is doing.

I myself have chosen to go with alternative 2 a) and got the so called rest of world tune from a 01 996 on my Box 01S. That way I got rid of the eternal CEL that I had for two years after catless performance header install. I first tried to move the downstream O2 sensors by lengthening the wires with thick wires to no avail, then tried so called O2 simulators but they did not work either. A good tuner would do the same but I like to be in some kind of control over what is in my car and also the original Porsche remap is much cheaper than a complete professional remap.
And there is no question about it; these engines can use the improved breathing, but I think you should do both the intake and exhaust at the same time. Hope this helps.

Excellent, thank you!

Yes I intend on headers, cat delete pipes and Borla exhaust, but that will be late spring, early summer.

Spent my current car fun funds on new bumpers, front, rear, body shop cost, new wheels, tires and a Euro Suspension Kit (ROW M030).

I still have car fun funds to do the air box change out right now. The tune deal, can that be held off until I get the exhaust done?

[Bfan]

Just go with Alternative 1. You will toast the engine if you run it for more than a few minutes with the big MAF tube as it will be runing in lean condition

[KRAM36]

Originally Posted by Bfan

Just go with alternative 1 You will toast the engine if you run it for more than a few minutes with the big MAF tube as it will be runing in lean condition

Is there a good benefit doing Alt 1?

Would buying a high flow air cleaner be just as good? Like this one?

Pipercross Air Filter Porsche Boxster 986 2 5L 2 7L 3 2L All Years | eBay

EDIT: I can wait to do the air box change too, just have some free time (February off) and looking for something to do.


.

[Bfan]

I almost say "This has been beaten to death her". But I say this: It is a well known fact that Porsche choked the Boxster engine on purpose. Just do a search on that. A high flow air filter will help to open things up but will it do what it is supposed to do as well as the one it replaces? To filter the air and stop all small particles from entering the engine? Maybe if you use the type that you oil but then you get a lot of issues with the oil getting on the MAF and messing up every thing. So I will not have one of those on my car/engine as I am concerned that it gets proper clean air. The 987 air box has proper filter with much larger surface area than the original 986 filter and that is only one of the benefits. The piping is also more open, the box has bigger volume (and bigger MAF house as mentioned). And it is a proper "cold air intake" as opposed to some aftermarket intakes that claim to be, but in fact get some of the air from the hot engine bay.

One thing that I failed to mention is that you should also do the 996 throttle body upgrade and 997 plenum at the same time as you do the 987 airbox and do something to open the exhaust. You don't want any weak links or bottle necks (as we say in my native language) in your stream of air through the engine. I think all these things work together and you only get full benefit from each, when you do them all. What you do to your exhaust depends on the state you live in, I am firm believer in performance headers, but they are down right criminal in some states, as known. And don't forget that exhaust can be tricky you can rob the engine of power with some expensive aftermarket systems.
If you are not aware of this tread her about 997 plenum and 996 throttle body, I suggest you spend half a day of your life reading through it. You will enjoy it, it is fundamental and real interesting reading.

And to answer your next question, my gussimate based on my 0-60 tests with an g-meter is that all these mods togeter give the S-engine about 30-35 extra horses. Worth it? I don't know. But it is dam fun process doing them all.

[KRAM36]

Originally Posted by Brad Roberts

From the other end, how far up is the screen located inside the 987 MAF housing?


I missed the picture, and it answers my question.

[KRAM36]

Also can the intake manifold gaskets be reused or do I need to get new ones?

[Bfan]

Well it depends.........they could or could not. I would believe they could, but you have to evaluate them after you open things up. It is not a yes or no question and not an yes or no answer

[KRAM36]

Originally Posted by Bfan

Well it depends.........they could or could not. I would believe they could, but you have to evaluate them after you open things up. It is not a yes or no question and not an yes or no answer

Thanks, I'll order some in.

I'm going to do your Option 1 for now. Got the complete air box assembly for $75 shipped. When I get ready to do the exhaust system, plenum and throttle body upgrade, it will be in there already.

I have this planned out pretty good I think. Only thing that will be larger is the air box itself. So the car won't run lean, correct?

Thanks for your help Bfan.

[edc]

Originally Posted by KRAM36

Only thing that will be larger is the air box itself. So the car won't run lean, correct?

Just for comparative purposes my old S was running a little lean with just stainless manifolds and a 2-box exhaust.

[The Radium King]

how could you tell - via the narrow band o2 signal to the ecu, or aftermarket wideband? if aftermarket, was the sensor placed before or after the cats? if using the afr from the ecu, did the ecu not correct the lean condition? also, at what rpm were you seeing a lean condition - part throttle, wot, or both?

[edc]

Wideband exhaust lambda probe on the dyno.

[The Radium King]

if the probe is in the exhaust post-cats then I've read that it will read a bit lean compared to actual products of combustion pre-cats (which is where the ecu gathers its data from) so your actual afr might be where it is supposed to be.

remember, regardless of what you have done to improve airflow (larger airbox, bigger plenum, bigger throttle body, better exhaust) the air still has to flow by the maf and be measured, and the computer just adds fuel based on the amount of air measured. so, as long as you are measuring air properly (ie, proper diameter maf housing) then things should be pretty much ok.

[edc]

I understand what you are saying and have similar thoughts. However, that car had 5 or 6 dyno runs on the same dyno with different mods over a period of time and the car in the configuration above was the only one to show lean running. Of course, that doesn't neccessarily mean its correct! Ironically, after the fitment of the 996 throttle body the AFR was back to 'normal'. You could interpret it as a spurious reading or that it indeed was running lean as the other 5 or 6 runs all seemed ok.

[The Radium King]

that is odd. I understand that at low and medium rpms the 'tuning' aspect of the exhaust and intake come into play (ie, using restrictions in airflow to time pressure pulses with valve opening) but fuel trims should react and fix any of that. did the ecu have time to compensate between exhaust install and dyno? was the lean condition present throughout the rpm range, or just at max rpms?

[jaykay]

Am very confused myself......

[edc]

I can't remember all the details as this was back in 2012. I still have the printed dyno plots but can recall it was leaning out towards the top of the rev range, perhaps the last 1.5k. The mechanical fitting had been done some weeks previously so the car had plenty of run time in between.

[The Radium King]

ok. my understanding of ecu operation is that during normal driving (part throttle) it is in closed loop mode - the engine senses the amount of air in, looks it up in a table, and adds fuel as per the table. it tries to maintain the magic air:fuel ratio of 14.7:1 for best power and efficiency of combustion. the o2 sensors in the exhaust monitor the products of combustion and provide feedback to the ecu - this feedback allows the ecu to trim fuel levels in order to maintain an afr of 14.7:1.

when the engine is working hard, ie in the higher rpm range, the ecu starts to worry about heating and detonation (the ecu can't control what kind of gas you put in, and can only modify timing a little bit). to address the issue it adds more fuel in an effort to cool the engine. this richens the afr to 12.5:1 or so. the o2 sensors only work in the 14.7:1 range, however, and can't provide any feedback to the ecu when operating outside of this value. as a result the ecu operates open loop and provides fuel based only on sensed air intake and fuel maps. my understanding is that, in open loop, it also ignores any fuel trim information compiled while operating closed loop.

so, my next question to you would be if you recall actual afr values when you encountered the lean condition at high rpm. I ask as this may not be a bad thing. in fact, this is the standard trick used by ecu 'tuners': they can't change ecu performance during closed loop operation (any modifications to the fuel maps would just get trimmed out) nor would they want to because the engine is already at 14.7:1. instead, what they do is lean-out the fuel maps during open loop operation to get closer to 14:7:1 (ie, set the engine to run at 12.7:1 instead of 12.5:1). you lose the benefits of the additional fuel cooling the engine, but gain power (more efficient combustion) and efficiency (less fuel used). this is why they often require that only high octane gas gets used with their tunes.

so, provided that the lean condition you encountered wasn't way out of whack, it wasn't necessarily a bad thing.