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Fabulous Modification for 987.1 3.2 liter engines

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16K views 16 replies 10 participants last post by  omarvelous  
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#1 ·
About five weeks ago I installed the throttle body and plenum from a Cayman in my 2006 Boxster S (which is equipped with the 3.2 liter engine). The installation instructions for doing so are given in the following fine article by berty987: Boxster Performance Modifications - Articles. I added a few comments to the article that I thought might help ease the installation. In short, I swapped the 68mm throttle body and plenum from my Boxster S for the 74mm throttle body and plenum from a Cayman—thanks prodgers for the parts.

To put what I have to say in perspective, note that I installed the following performance modifications on my car prior to the above: impact absorber plate delete (aka de-snork), EVOMS V-Flow intake, NHP race headers, and FVD flash. My month-long seat-of-the-pants judgement is that the throttle body and plenum swap is the equivalent of the sum total of all my prior performance modifications—it is that good!

The torque increase is very evident starting around 2500 rpms and it never lets up. The car pulls in a hard and linear fashion right up to the engine cutout at 7400 rpm. If you examine the dyno graph in the article you will see that over some rpm ranges the torque increase is approximately 25–30 foot-pounds, and just as important, it never dips below the torque produced by the OEM throttle body and plenum.

One can purchase the IPD plenum and 74mm throttle body from FVD for over $1200, but the Cayman throttle body and plenum swap has to be the best bang-for-the-buck modification for the 2005-2006 Boxster S, as I spent $1000 less for the OEM parts!

Congratulations on a well-researched modification and article berty987!
 
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#2 ·
Professor MSP

WOW!! so you got this project completed ! I was wondering when I would hear from you :) that is just fantastic that you pulled this off ,I cannot believe what a difference it made in your cars performance ,amazing!

And we both discovered before you started this project the 2.7 and the 3.4 Cayman share the SAME SIZE PLENUM from the porsche factory .
I am glad this worked out for you ,you have paved the way for any 3.2 liter owners that will want to do this mod as well.
was the installation hard ?

Great job -Professor MSP I am happy to have helped you ;)
 
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#3 ·
Re: Professor MSP

Thanks prodgers. I am really happy with the way it turned out.

The installation was time-consuming (5 hours) and a bit fussy. There is not a lot of room to fit the larger plenum in there, so having a friend of mine help was crucial to my success—four hands are better than two! berty987 gets the credit for this modification, however, as he did the research and the initial installation on his car.

Regarding the PM you sent me, I received the following: "prodgers has exceeded their stored private messages quota and cannot accept further messages until they clear some space." In any case, go ahead and send me the part you found.

Thanks.

prodgers said:
WOW!! so you got this project completed ! I was wondering when I would hear from you :) that is just fantastic that you pulled this off ,I cannot believe what a difference it made in your cars performance ,amazing!

And we both discovered before you started this project the 2.7 and the 3.4 Cayman share the SAME SIZE PLENUM from the porsche factory .
I am glad this worked out for you ,you have paved the way for any 3.2 liter owners that will want to do this mod as well.
was the installation hard ?

Great job -Professor MSP I am happy to have helped you ;)
Click to expand...
 
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#4 · (Edited)
Good to hear that you are pleased with the result. I took inspiration for this mod from the GT3 , IPD throttle body mod which is well publicised on this forum elsewhere , though sadly demonstrates a slight loss in torque over stock as a result of removing the split intake distributor. With so few tuning parts available for the 3.2S , I decided to do some research and develop my own solution. Personally I like the idea that this mod is DIY and uses standard porsche parts , making it excellent value for money , particularly if the parts are sourced used.

The 2.7 and 3.2 M96 engines (987 versions pre 2007) both use a 68mm Throttle body , the 2.7 and 3.4 M97 engines (from 2007 on) use the 75mm throttle body. The 75mm throttle body is identical to that used on the earlier 996 carrera and also the cayenne 3.6.

All 987 engines use a split intake distributor tube downstream of the throttle body. I researched the purpose of this design and its function , which is to increase low and mid range torque , therefore ideally it should be retained on any upgrade.
Unlike the SRP or IPD plenum and throttle body mod , this mod uses the original porsche split intake distributor from the 75mm TB, so there is no loss in torque mid range , this was a key issue for me when researching this mod.

It would be interesting to see what a power and torque curve would look like if a simple adapter plate was coupled to a Gt3 TB on the original 80mm ID split intake distributor on a 3.4 engine. Though there will be a restriction (80mm ID versus 90mm ) by using the original intake distributor , there is still a gain over the original 75mm throttle body by using the 82mm unit.



A few more "budget" tuning mods are in the pipeline , keep a watching eye on the technical articles section for updates.
 
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#6 · (Edited)
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#9 ·
These are the exact numbers on the parts I installed. Best of luck with the installation, and please report back with your impressions once you have had some seat time with the modifications in place.
 
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#11 ·
Unfortunately, I cannot confirm that the 987.1 Cayman S 3.4 plenum and throttle body will fit a 986 Boxster S 3.2.

I recall that the 3.2 M96 in the 986 Boxster S is much the same as the 3.2 M96 in the 2005–06 987.1 Boxster S, but they are not identical. For example, my engine number begins as M96.26, whereas the 986 Boxster S has different numbers after the decimal point. I do not know if the differences between the two M96 engines would matter for the installation of the 987.1 Cayman S plenum and throttle body, however. If I were to guess, I would say the 987.1 Cayman S plenum and throttle body can be fitted to your M96 engine in the 986 Boxster S. The couplers from the throttle body to the intake manifolds would need to be carefully measured to ensure you purchased the correct sizes.

Sorry that I could not be more helpful.
 
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#15 ·
Is this a mod that people still do? I have a 987.1 boxster s and am planning my intake upgrades. If a 3.4 cayman plenum and 74mm (is that correct) tb is an upgrade that would be nice. I like factory stuff. Do you need new couplers and things of that nature? I searched around and didn't find much on this everybody seems to use IPD but it's expensive and I don't like the idea of sacrificing low end for some hp up top..
 
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