QikQbn's 98 Porsche Boxster Story

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The Journey: 2.5 Liter to 3.4 Liter Engine Conversion

20,000 plus visitors!  Thank You very much for visiting! My name is Bill Diaz and I created this website many years ago to share my passion for Porsche cars. I also wanted a forum to share the struggles and joys I have had owning several different models, modifying, maintaining, and working on Porsche cars over the last 16 years. I am honored that you have stopped by to take a look.  Be sure to check out my other Porsche Projects in the links to the left. Thanks!!


Check out Matt Farah's Review of my 3.4L Boxster on the Smoking Tire Youtube Channel !!  


Boxster Blasting through the canyons Sites and Sounds video:


 Wheelwell.com:   https://www.wheelwell.com/profile/54eb78e310875dd35821214d/vehicles/54eba03110875dd358212260/specs/

Qik Qbn = Quick Cuban (A license plate I have had since High school) I know, I know.... my friends still bug me about it too! 

These pages are dedicated to my passion and hobby. The need for speed, driving and working on Porsche cars. In particular is a highly modified 1998 Porsche Boxster. This is the 1st Porsche I owned and I purchased this 1998 2.5 liter Boxster in the year 2000. It came with a nice sport package option which included 17inch 5 spoke twist wheels 17x7 front and 8.5 rears with 205/50 and 255/40 tire sizes, upgraded suspension, traction control, trip computer, aluminum door sills, wind deflector, aluminum shifter, sport exhaust tip, and cd changer.

One of the first big upgrades I did was add on 18 inch Carrera lightweight wheels along with clear front headlights, sidemarkers, and rear tail lights. Although I had a history of modifying and upgrading all my previous cars to go faster and handle better, it was the Porsche mid engine Boxster that changed the way I look at the sports car world.  By upgrading the power and suspension on this car I have acheived an amazing driving experience. One that, in my experience of driving lots of sports cars, has become a bench mark in handling and overall driving experience for all others to meet. 

Porsche "Excellence" Magazine did a wonderful article on my Boxster in April 2010. There are many great details about the conversion process written in the article along with a wonderful driving review by Zachary Mayne.  It was an amazing honor to be in Excellence Magazine. See link in the left column or go here to see article:


To See photos done By Zachary Mayne for the Excellence Magazine article go here


Rolling on some new "Spyder" wheels. 19x8.5 front 19x10 rear.

Shortly after getting the car I started looking for go fast parts and upgrades. At first they were small additions like K&N intake and Powerchip upgrade. I had the car dyno'd and it made a respectable and fun 220 hp at the crank. I added aluminum colored interior parts for center console, center vents, door handles, shift knob with silver horse shoe, and tequipment silver and black 3 spoke steering wheel, and B&M short shift kit. The body kit consists of a 2004 Boxster rear bumper and the front bumper and side skirts from Tequipement Porsche Aero kit 1 from model year 2000. Part number is:
Boxster part no.   000 044 800 80
Boxster S part no. 000 044 801 66

For the first 7 years and 90,000 miles of ownership I enjoyed the 2.5 liter engine slightly modified with intake and ecu upgrade.  Here were the dyno numbers at the wheels:

Stock 2.5 liter: 170 hp 152 tq @ wheels x1.2 =  204 hp 182 tq @ crank                                                           Ecu + intake : 183 hp 165 tq @ wheels x1.2=   220 hp 198 tq @ crank

Gtech pro times for 2.5 liter engine making 220 hp:

0-60 mph 5.7 secs, 0-100 mph 15 secs. 1/4 mile 14.2 @ 97mph


The heart transplant. 3.4 liter 911 motor modified to about 324 hp 280 lbs torque

After 6 years and 90k miles of enjoying the 2.5 liter sound and power it was time for a big change.I had modified the intake and computer chip on the 2.5 to make about 220 hp at the crank. (183 hp and 165 tq on the dyno)  and I enjoyed it for a long time that way, But the boxster chassis could handle so much more.

For a majority of my conversion parts I contacted and became friends with Todd Dakarmen who owns LA Porsche Dismantlers (818-767-7243) http://www.ladismantler.com .They specialize in stripping out the good parts from Porsche's that have been crashed and not had happy endings. But their good parts live on making other owners happy. They are located about 15 minutes from my work and I used to stop by there atleast a few times a week looking at the latest engines and parts to arrive. I got a call from Todd one day asking me to come by to look at a great find.  It was a great 996 3.4 (300 hp) motor with only 18k miles on the odometer.  The Engine Donor car was a beatiful black 996 Carrera that from the doors back looked immaculate.  Someone had run a red light and smashed right through the whole front end.  I was able to sit in the car and start her right up.  The odometer only showed 18,000 miles. I purchased the 996 3.4 engine, wiring harness,996 ECU, 2004 Boxster S muffler, and Boxster S front mount center radiator.  Besides supplying engine parts Todd has been a tremendous help to me. LA Dismantler has been an incredible resource for my porsche parts need. I also got upgraded 996 front calipers, rotors, tequipment front bumper, 2004 rear bumper, xenon head lights, updated porsche stereo, and so many other parts that I have lost track.  Todd Dakarmen has been an incredible source of Porsche wisdom for me through that whole process.

For brand new parts I call the guys at Sunset Porsche in Oregon. 800-346-0182. They have the best prices around for new parts.  Cost plus 15%... I got great prices on the RoW (Rest of World..non-USA) M030 Sport Suspension.The "ROW" M030 adds lower/stiffer springs (front lowered 20-25mm, rear 10-15 mm) A set of tuned front and rear Biltstein shocks, and thicker front and rear sway bars. This System was tuned by Porsche and is best installed as a unit rather than ordering parts serparately. This in combination with 7 mm H&R spacers all around and 18 inch light weight Carrera rims is a very nice compromise between sporty aggressive driving and daily commuting.

For all the engine and suspension installation I contacted Claudio Szyszkowski's shop...Foreign Sport Technicians in Santa Monica. 310-394-0369. Claudio has been written up in Excellence Porsche Magazine (June 2000) doing this same conversion back in 2000.  So Claudio has great experience working on both Porsche and Ferrari's.  His work is meticulous and he was very helpful in answering all my questions and making great suggestions for a more bullet proof installation.. He fabricated and modified many parts to work with the conversion.  Fuel lines and rails had to be modified to work with the 180 degree engine turn around. Spacers were created to drop the motor 1 inch so it would clear the engine cover.  The ECU wiring harness was modified as well to work with the 3.4 liters additional signals and sensors needed to control intake manifold valves, vacuum lines and plenum that were not part of the 2.5 liters original ecu wiring. Claudio had the car for close to 3 weeks. It could have gone faster, but many times we were wating for parts to arrive for the things we found that looked a bit tired and needed replacing while we were already in there.

ECU Tuning was a break through for me, but not how you may think. I originally had "powerchip group" reprogram my ECU with their 996 3.4 liter sport program, but for some reason I was still running very rich.  I then contacted a dyno shop in Gardena and met Steve Rogers, owner of SR MotorCars (310-516-1003).  After doing a few dyno pulls and seeing very rich air fuel ratios I discovered Steve has some amazing experience with tuning import cars and was in the research and development department for APEX electronic tuning products for 5 years. He has great insight into tuning air fuel ratios.

After discovering that I was running very rich and my Air fuel ratio readings were around 10:1 under wide open throttle it became very clear that my car was down significantly on power.  The basic idea we discovered is that the MAF housing diameter for the stock 3.4 liter 996 intake is 3.5 inches.  For the stock 2.5 liter Boxster airbox the intake MAF housing is 3 inches. A 20% difference in size and readings.  When the 3.4 liter motor is drawing in air it is pulling air in "faster" through the smaller stock boxster 3 inch MAF housing instead of the stock 996 3.5 inch housing it was oringinally programmed for. This  20% difference in "faster/higher" voltage signal sends a reading to the996 ecu that calls for more fuel and therefore richens everything at wide open.The opposite can happen if your MAF housing gets too big, which could lead to a lean situation.

We wanted to be able to fine tune as needed so Steve recommended the "APEX AFC-SELECT" for german cars. This unit is a Mass Air Flow voltage controller.  They are hard to find these days, but they are out there. I found some on ebay.  I also installed an AEM wideband Air fuel ratio gauge to monitor AFR's from within my car: 



The APEX AFC-Select allows the driver to control the voltage reading of the MAF signal at any designated rpm before it gets to the 996 ecu. By doing so the 996 ecu takes the new voltage reading and adjusts the fuel injectors as required.  Thus we were able to fine tune my AFR to read a conservative 12 all across the board.  From this tuning alone I gained 20-30 lbs of torque and horsepower across the mid rev range from 3500-7000 rpm.  I was stunned and amazed at the difference!  The whole process of installation and tuning took about 3 hours.  Now I have a system that I can fine tune to my unique modifications.  I would highly recommend this procedure over any "ecu rom tuning" in a heart beat because everyone's car mods are different. This eliminates wondering if your "reprogrammed chip" needs to be adjusted if you ever ad anymore bolt ons.

Steve's knowledge of the product and ease of use was paramount to making it happen so smoothly..Now granted this is not adjusting timing and other parameters that rom chips do, but for most bolt on mods that deal with faster air flow this is a great solution.

We wanted to start out conservative and tuned the air fuel ratio to hold 12:1  across the entire rev range at wide open throttle.  We will later be raising it to an AFR of 12.5-13 which should result in a gain of another 10-15 hp and tq. For this test we will keep it conservative and safe at 12 for a few 100 miles to make sure no check engine lights or problems show up..   

**My before and after dynojet peak dyno readings at the wheels were as follows:

Rich AFR=10: 255hp @ 6300 and 215tq @ 4600 (wheels) X 1.2 = 306 hp and 258 tq at crank

new AFR=12  :270hp @ 6300 and 235tq @ 4600 (wheels) X 1.2 = 324 hp and 280 tq at crank

vehicle weight 2750 


**compare this to dynojet readings of stock 996 below:

 2001 996 3.4 liter factory crank hp 300hp and 258 tq:

Dyno =  251hp and 213tq  X 1.2 = 300hp and 256tq  at crank

AFR=13                    vehicle weight 3000 lbs.

**2002 911 3.6 liter Factory crank Horsepower 320hp and 273 tq:

Dyno = 265 hp and 228 tq X 1.2 =320 hp and 273 tq.

 AFR=13 vehicle weight 3100 lbs.


Car has now been dyno'd with approximately 324 hp at the crank and weighs only 2750 lbs.

Gtech Pro RR g-force accellorometer performance run:

0-60 foot launch 1.9 sec

0-60 mph in 4.4 sec

0-100 mph in 10.6 sec

0-130 mph in 17.3 sec

0-150 mph in 27 sec

Quarter mile time 12.8 sec @ 110 mph.  

see on youtube:

0-100 mph in 10 seconds ;^)


0-130 mph in 18 seconds on track.



Videos of my pcars while at PCA event. 19x8.5 + 19x10 Carrera sport wheels on Boxster  (2010-2014)










**2009 Update to intake maf housing....

I recently replaced my stock 3 inch Maf housing with a Cayman S 3.5 inch maf Housing.  Now I know for sure that I am getting the proper fuel maps from the 996 ECU without any voltage correction. Now I have a better starting point of reference on the maf signal that was designed to work with the 996 ECU. I then fine tuned the AFR signal just a little bit with the Maf voltage controller to smooth out some dips. Overall I have a much better peace of mind with my current setup and my Air Fuel Ratios at wide open throttle are dialed to stay between 12.5-13:1..


3.4 liter engine installed... IPD Plenum, Cold Air Intake


List of upgrades and engine modifications:

--996 3.4 Liter engine

--boxster S front center radiator

--Sport headers, B&B TriFlow

--modified cats, original cats with larger diameter tubing

--upgraded powerchip computer,

--IPD throttle plenum,

--2004 boxster S exhaust.

--Highflow Cold Air Intake and 3 inch tubing to throttle body

--Apex AFC-Select --Mass Air Flow Controller

--AEM "UEGO"  Wideband Air Fuel Ratio Gauge 


Suspension and brake modifications:

--Updated 2003- 996 Carrera light Weight Wheels 18x7.5 front, 18x9 rear 

--Tires Continental ContactSport N2  (225/40/18 front, 265/35/18 rear)

 --**2010 Update Wheels:  Carrera Sport 19x8.5 et 55 front, 19x10 et 42 rear

-- 2010 Tires Hankooks V12  235/35/19 front  275/30/19 rear

-**Update Tires. 10/2013  Michelin Super Sports 235/35/19 front 265/35/19 rear added to Carrera Sport wheels.

275/30 rears were great, but some angles looked a hair wide.. 265/35 look great from all angles ;^) 

have Michelin Super Sports on all my cars now.  Highly recommend this tire ! 

**Update 11/2014.    Boxster Spyder 19 inch wheels. 19x8.5 et 50 front + 5mm spacer, 19x10 et 42 rear.  Michelin Super Sports 235/35/19 front 265/35/19 rear  


**WHEEL AND TIRE PAGE    http://www.qikqbnboxster.mysite.com/photo2_3.html 


--996 Carerra Front Brake Calipers and Rotors

--996 Carerra Rear Brake Calipers and Rotors

--Steele Braided Brake Lines

--RoW (rest of world) M030 european sport spec suspension

made by Porsche specifically for the Boxster, which improves handling and lowers car

about 1 inch. Suspension kit included 4 new springs, 4 shocks, and  front and rear sway bars..

--H&R DR Series 7mm wheel spacers and extended bolts all around used with 18" Wheels

--**Update 2013 . For 19' Carrera Sport 19x8.5 et 55 front wheels using 11mm Brey-Krause Hub Centric-Extended wheel spacers front axle only. no spacers needed on rear axle

--**Update  2012  H&R Adjustable Rear Anti-Roll Sway Bar 22mm diameter.  M030 rear sway bar was great, but H&R 22mm added a bit more stiffness in rear.  Handling Understeers less now.  By widening the front track with tires and spaces and also a stiffer rear sway bar have changed the handling to a bit of a oversteer characteristic. Fun!


Body modifications and interior:

--Tequipment body Aero I body kit (front bumper, side skirts),

--Cayman style rear wing 

--2004 Boxster rear bumper.

--Upgraded canvas top with glass rear window by "GAHH"

--Porsche 996 Short Shifter.   000-044-700-26-OEM  (similar to B&M Short Shifter)

--UPDATE 4/2015  Got the 997-424-983-00  Short Shifter with Blue plastic shift cover.  Tried it out on the Boxster and it was better than the 996 short shifter 000-044-700-26-OEM, but still a bit notchy. 3rd to 2nd downshifts still took some effort.  Decided to put that 997 short shifter in the Cayman S and took the Cayman S shifter 997-424-010-00 and installed it in the Boxster. Feels really nice.  Definitely still shorter then the stock boxster shifter, but not as short as the B&M style. The 997/987 stock shifter works great in the 986 Boxster.  Smooth and precise.  Still wished it was a bit shorter in throw, but a really nice upgrade still. 

--Tequipment Aluminum 3 Spoke steering wheel

--Aluminum Pedals

--Aluminum look interior accents

--Silver hard back and heated Sport Bucket Seats

--Tequipment Spyder 550 Oval Split Exhaust Tip... Using double barrel style tip more often ;^)

324 hp 3.4 liter Boxster with Aero body kit and RoW M030 euro spec sport suspension

Lots has changed, an amazing sports car. Gtech Pro results below

Gtech Pro is an accellerometer unit that hooks up to the windshield and measures

g-force in order to calculate speed and time.  Very similar to what the car magazines

use to test all of there vehicles performance. 

Gtech PRO-RR Pass program displays results on your computer at home. Here are A couple

of runs done prior to the AFC-Select tuning: Notice how the "60 foot" Launch makes

all the difference in elapsed times. Spinning tires or bogging engine on the launch ruins your times.

Porsche's are not really meant for the drag strip, but it is still nice to get a good 0-60 mph and 

qtr mile time to see how it compares with other cars and power to weight ratios...


Any comments or questions? 

Email:  qikqbn77@hotmail.com

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