Bump for the latest update?

all the parts in except for one. it looks like it will go together easy. finally understand why porsche uses a tb smaller than the maf housing; the maf is a thin-walled plastic and the inside diameter (3") is about the same as the outside diameter (3"). the throttle body, however, is cast; the inside diameter is 2.67" while the outside is 3". that way you can use a 3" pipe to join maf and tb but have a smaller tb as a result.

so, by going to a 3" tb to match the 3" maf, the throttle body has a 3.25" outside diameter. i've got a 90 degree reducing elbow (3.25" to 3") on order to join the two; once it arrives i'll assemble.

Go TRK go !

Thanks! Would you post a few pics once done?

Blast he is ahead of me! Just have the throttle body in today! It's very shinny. 997 Diverter tee and hardware awaiting shipping. I can report that the Cayman piping is easier in that it will have only one reduction from the MAF as far as I can see. Have to pick up (if it is good) the Cayman airbox on the weekend.

....Trk thanks for the leads got an expensive tb out them

May do another version with the stock airbox

does anyone have a parts list for this mod. ? i would really like to give this a go .

Some eye candy:

http://986forum.com/forums/uploads01...1330485652.jpg
http://986forum.com/forums/uploads01...1330485670.jpg
http://986forum.com/forums/uploads01...1330485711.jpg


The 3.8 diverter tee is big! This the 74.5mm TB on it.

and one more:

http://986forum.com/forums/uploads01...1330486173.jpg

MAF and Throttle Body Diameter Increase
 

Bump to see if there are any new developments!!

Throttle Body to Airbox Angles & Clearance...
 

Hi, I came across this thread this morning while looking for a solution to my own induction problems.

A solution being put here is to use the 997 plenum. Now this does not curve unlike cayman/boxster plenums.

I currently use the engine & induction setup from a late 3.6 996. Now the plenum angle is similar to that of the 997. The issue it gives is that to connect the TB to the airbox you have to immediately use a v sharp immediate 90 degree bend in order to clear the bulkhead to the rear of the luggage compartment.

My feeling is that any gains from this plenum will be negated by this v tight 90degree turn into the TB. I can provide pics if that helps.

Any thoughts??

sure. with your setup (or a 997) you need the immediate 90 off the throttle body, but benefit from an equal 90 turn into each intake manifold. with the oem setup you get a shallower approach to the throttle body, but a resultant 135 degree bend to one of the intake manifolds - more opporutnity for delamination, turbulent flow on the inside of the curve and reduced airflow.

I see a lot of engine conversion intake plumbing with sharp 90s into the throttle body. I personally will try to avoid this with the largest radius 90 out the throttle body I can find and then a 30 deg to correct for the angle away from the intake side.....currently I am eye balling it and have not measured the engine intake diverter tee angle.

Interestly I have noted pitting on the inside of my low time cayman tb, coincident with the outside radius bend of the cayman diverter tee and intake path. This gives me the feeling that presenting the air flow straight through the tb may have some value; less turbulence

Thanks for that, I hadn't considered the problem of the tighter inside radius on the curved plenum.

My car is an older 2.5 so was a cable throttle. I can confirm upgrading to a cable 996 3.4 TB is a big increase in power. I think this starts at 76mm & tapers down to maybe 74mm-ish at the butterfly.

I do have a previously fitted cable 80mm TB. This was an aftermarket ebay Nissan GTR TB. Its a good fit just needed oversized mounting holes, & an adapted bmw iacv plumbed in to the aos take off. It did from memory lack some torque below 4000 rpm compared to the 3.4 TB.

I think I may revisit this set up as I think its a shorter length compared to the 3.4 which means a less angled pipe could be connected.http://986forum.com/forums/uploads01...1331712850.jpg

New Air Intake Options
 

Gotta Bump this up - looking for the latest from you intake enthusiasts!:cool:

The cayman uses the same 74mm TB as the 3.6 996 and early 997 3.6/3.8. The gen 2 DFI 3.8 L engined 997 uses the larger 82mm TB. Regarding the mounting tees for the 74mm TB the cayman 987 and the 996 / 997 both use a larger diameter bore on the cross section that links the two halves of the intake manifold. Whichever you fit , you need to install a silicone reducer to get it to connect to the existing 986 / 987 intake manifolds. The 2006 and later boxster/ cayman use the 74mm TB and revised intake manifolds as standard in both 2.7 and 3.4 engines. I did a little write up on the 74mm TB fitted to an early 987 3.2S here :

75mm TB and Cayman Plenum upgrade for 987 - Articles

Note : If you fit a 987 airbox and MAF to a 986 (as was standard in the 550 anniversary) the install applies though the second diverter after the throttle body would not be connected or operational on a 986. The intake manifolds of the 986 were carried over to the early 987 models up to 2006 when the M97 engine was introduced.

For you guys with 986's I guess you have the option to break out the inner wall that divides the air paths post TB and remove the diverter flap as well. The cayman diverter flap looks wrong to me , its across the airstream creating a baffle whereas the earlier 987 boxster unit had the diverter parallel to the air stream , so created no restriction when open.

So, for the mechanically impaired, where are we at now in terms of the parts and equipment necessary to complete this modification ? What are the actual specs regarding choice of TB and plenum ?

For an E gas 986 (ie electronic rather than cable operated throttle body) you need a 74 mm Tb from a 3.6 Cayenne / 3.4 cayman or boxster or late model 2.7 cayman/boxster 996 605 115 01 / 997 605 115 00 and either the 996 tee 996 110 116 01 or the cayman tee 987 110 116 01 plus shorter screws 900 385 025 04 (4 off) , and larger clamps 90-110mm 999 512 539 01. You then need to buy two silicone reducers 102mm to 89mm (ideally 99 to 89 but they don't exist) plus some fabric tape (to pack out the slack on the intake tee under the silicone hose) and lengths of silicone tube to connect the air box / maf to the throttle body intake. If you use the 987 cayman inlet it may be possible to simply use the accordian tube from the 997 or cayman 987 to join the throttle body to the airbox/ maf 987 110 222 00 or 996 part 997 110 223 00.

You can identify the parts/ options using the online parts catalogue here :

http://www.porsche.com/all/media/pdf/originalparts/en/E_987_KATALOG.pdf

Just use the M97.20/21/22 option under the 987 model or the m96.05 under the 996 for 74mm TB parts.

Though i've not tried it , the 944 airbox tube looks like it may also be worth a look as a connector between the Throttle body and airbox housing if using the 996 tee, it already has a nice radiused curve.

So, has the 76mm TB been ruled out ?

the 74 mm, 75 mm and 76 mm is just different people measuring the same thing. call it 3" and be done. similarily, for reducers use 3.75" to 3.5" that are readily available.

Bump for any new developments....

very interested in this also .. subscribed .. thanks for the great read so far TRK

sorry all. been too busy moving across the country, driving and, most recently, dealing with an (i hope) rms leak. all parts are in a box, hopefully to go in before the end of summer.

the road to hell ...

King,

Any updates on the project ?

Suscribed

TRK I would love to see some pics when installed (and hopefully dynoed)

So, what is new?

got the old stuff torn out and just putting it together now; i'll post pics and part numbers once i get it running in a few days.

Super! I am 100% sure a lot of us can't wait!

Thanks to this thread - I will have to start digging in my V8 Touareg to measure the throttle body there. Thing looks identical. and those are dime a dozen on ebay. Will post once measured.

Any new news? Inquiring minds want to know! Have been waiting for the saga to continue.

Well, I will order the parts this or next week. Only thing I have to figure out how to connect from the TB to the (stock) intake.

i'll have more soon. what i can say is that the oem rubber couplers are stretchy enough to fit the larger plenum, but you can also get silicone reducers to do the job (dimensions posted earlier in this thread). the aos line will fit, but perhaps get a hair dryer/heat gun on it to make sure it doesn't crack when repositioning.

the larger 3" inside diameter throttle body has a 3.25" outside diameter. further, the oem maf housing/airbox has a 3" inside diameter and a 3.25" outside diameter. so, you need a duct that is 3" inside diameter but will fit over something 3.25" in diameter. several options:

- you can get that spectre flex 3" duct with rubber boots on each end (the rubber should stretch to 3.25"). folks say to not use rubber, but it's good enough for porsche ...

- you can do similar to what pedro does and use the oem duct; cut the resonator box out and tie to a 3.25" long-leg elbow to the throttle body. that dog don't hunt for me, however, as the oem duct is very thin and will easily collapse if you tighten the hose clamp too aggressively.

- you can try what i'm attempting - throttle body to 3.25" elbow. saw oem maf housing off of airbox and attach to elbow (this gets the maf closer to the throttle body like on the 996/997 for more responsive readings). 3" flex duct to bmc dynamic air intake located where oem airbox once was. This is a bastardisation of what has already been done by insite and jhandy (and others i'm sure).

** edit to add that i've read in several places that using a bmw 3-series maf housing is equivalent to sawing off the oem maf housing however, having ordered one and compared the two, the bmw unit is 70 mm inside diameter and the porsche unit is 74 mm (so, i've got a bmw maf housing for sale if anybody wants one ...).

Ordered the parts! Should have tem next week.....

ok, throttle body is in:

http://986forum.com/forums/uploads01...1342585644.jpg

i used the oem rubber boots to install the plenum (otherwise use two 3.75" to 3.25" reducers). you can see the aos tube; not connected but will go on once i get some heat on it. the whole thing clears the engine cover, throttle connector plugs right in. removed the bracket that the previous throttle body bolted to; replaced the bolts that held it in place because they went straight through to the bellhousing (used washers to get same depth as previous).

so, final parts list is:

one $42.43 997 110 416 03 997 plenum
two $ 3.05 999 512 539 01 hose clamp (for the larger plenum)

four $ 0.27 900 385 025 04 bolt (larger throttle body requires shorter bolts)
four $ 0.15 N 011 524 27 washer (for above)
one $ 5.49 997 110 319 00 throttle body gasket

and one 74 mm throttle body from a 996, 987 or cayman. i bought mine used for $100 as there are lots around (996 from wreckers, cayman from guys who do the gt3 throttle body mod to their cars); find the right seller and you should be able to get the bolts, washers and gasket as well.

the final step is the connection from throttle body to maf housing. you need a 3" duct that will mate to the 3.25" flanges on the throttle body and the maf housing. i recommend the following $20 spectre 3" flexible duct because it has a rubber lip that should stretch to 3.25":

3" Dia Air Intake Flexi Ducting Air Intake Tubing Expands for Universal + CLAMPS | eBay

i haven't done that as i'm doing a custom intake as part of this project, but figure it should work ok. other options are a custom silicone build or repurpose the oem duct in some manner. regardless, all in for under $200.

and no, i've no idea if it improves power; by the time i get my car running i'll have the larger plenum and throttle body, new intake, udp, deleted AC, cleaned injectors and lighter rims; i'll have no idea where the improved performance is coming from (as long as there is improved performance ...).

Looking good! I ordered my parts already, they are on the way. Must have been hard to get those OM rubber boots on the larger Tee??

not at all; more than stretchy enough. gives it a stock appearance. what you see in that pic is less than an hour of work.

Well, I ordered silicon reducers, hope they work, otherwise I will follow your lead! Thanks for your feedback!

yeah, i'm going to keep an eye on the rubber to see how it wears; bad place for a leak. 12 years old and still supple, however; must be all the oil my aos is puking into my intake that's keeping it in good shape.

Getting there!



http://im1.shutterfly.com/media/47a2...D550/ry%3D400/

http://im1.shutterfly.com/media/47a2...D550/ry%3D400/


This Spectre air duct is not too bad! Got it at AutoZone today.... All other parts are brandnew.

Install should be fairly easy, only "worry" I have is the AOS connection, hopefully nothing will break.

the aos took me as long as fitting the plenum. get a heat gun and get the heat to it - it responds well to heat. a bit of meticulousness and you will get a perfect fit. the clips at each end of the aos tube don't like shear load (only tension) so make sure you form properly for the clips to hold.

looking good; you can be first to report perceived benefits.

Thanks for the tip! And yes, hopefully there will be some gains, let's see :cheers: