The following information is provided for your entertainment only!
No warranty applies, is implied or given. Proceed at your own risk!
Have fun!
 Updated 5/10/98
Performance mods 

(some mod's listed below legal for use off-road only!) 

"Establish a relationship with your local race shop and parts supplier. These people will be an invaluable source of help and information. The mistakes you are about to make are not new. They have been made before. These people have made them! Learn from them... These people have a wealth of knowledge that you can make good use of..." 

source: WINNING A Race Driver's Handbook, George Anderson 



* aftermarket chips for '85 and newer (earlier requires custom chip and cost may be prohibitive) 



see Dinan Engineering, Mountain View, CA 

see AutoSport Design 
custom chip programming on chassis dyno!

* DEVEK Performance 6-liter stroker modification - email for free catalog & parts info! 

* camshafts 

* headers - Devek or MSDS (see Nopi) or 928 Specialists 

* cat bypass - not recommended due to environmental impact but reported 10 - 12 HP gain on track use. see Europroducts 1-800-962-0911 or GPR 

* Replacement mufflers/systems 

The current rage are the muffler bypass pipes available for 86.5 - 95s.  These pipes are a true bolt-in, sell for under $200 and come in three styles - plain megaphone tips in flat black, polished tips and stainless.  David Roberts of 928 Specialists  reports a significant weight reduction vs. the stock final muffler, with the added bonus being this weight savings occur outside the 'suspension box', similiar to Honda's mass centralization weight management theory.  The bypass pipes are available from 928 International, David Roberts as well as in Panorama magazine. 

Numerous other sources for bolt-on ie. Ansa mufflers and weld-in ie. , Borla, B&B , and also Flowmaster, Powertone, Supertrapp etc.  Don't be afraid to try traditional muflers such as Thrush, Hedman, Edelbrock, etc. The catch on muffler mod's is to get the sound you want while maintaining power-curve desired. Remember, the 928 engine is a highly tuned and balanced 'system' - even a simple muffler swap will change the output characteristics, sometimes reducing power at one rpm level while boosting it at others.   These systems are also very expensive as they are custom bent & welded to fit.  For a high-horsepower 928 engine, this is your only option for max gains. 

*  5/10/98 Exciting update!   How about a true dual exhaust, twin FlowMaster bolt-in setup for $500 complete!!!    Check out the  928 Specialists!

* hi-flow fuel injectors - see DEVEK , RC Engineering, and / or Marren Motors 

(thanks Kenneth Hartley, porschefan for the info on Marren!) 

* hi-rate fuel pressure regulators - Bosch adjustable FPR .  Don't go too wild, you might blow out your injectors!  

* extrude hone ram tubes - see DEVEK for 928-specific mod's or ExtrudeHone Corp. 1-310-531-2976 for general info 

* big bore throttle body - see AJ USA

* K&N Filterchargers - never buy another air filter again! 


* Spark plugs - TorqueMaster - Bosch (use GTS spec for S4 and later) -  NGK - BERU (new quad electrode)

* Wiresets - Magnecor 1-810-669-6688 

* Ignition also see NOLOGY 1-800-NOLOGY1 

Driving out on the edge?  See Electromotive ; Motec ; or Haltec systems 

* Underdrive pulley see Unorthordox Racing 

*Turbocharging - Callaway - Turbo magazine - Protomotive - other 

* Supercharging (Procharger / Powerdyne / Vortech) 

- see Excessive Motorsports 1-816-224-8849 

- see photo & text below!!! 

porschefans excerpt: 

" I have a couple of 928s; a red one fully prepared for autocross/time-trials, and one highly modified black street machine (plus tons of spare parts, engines, etc). I'll skip my autocrosser (this one is fully sorted), and talk about the black one ("Porscheneggar"). Based on a 1986 US model, it has the full DP wide-body conversion, and a 32 valve, supercharged engine. Again, I won't waist time (bandwidth) talking about body/suspension stuff--so here's the engine/drive train: 1) Camden (Roots-type) supercharger. 

a) 7.5lbs (measured) boost. b) 15 lb pop-off valve (safety from intake backfires). c) Four 90lb injectors, running on top of SC (wet). 

2) Pistons are milled, for a static CR of 7.5:1. 

3) Custom aluminum manifold. 

4) Massively ported heads. a) Larger valves. 

5) 100mm throttle-body, breathing through 12" x 6" K&N. 

6) Electromotive TEC II, running SuperBlend=AE software. a) Crank trigger. b) TPS sensor. b) MAP sensor. c) MAT sensor. d) Coolant sensor. e) Coil per cylinder (no machanical distributor). 

7) MSDS headers, jet-hot coated. a) Dual 2.5" exhausts. b) Dual 2.5"/2.5" Edelbrock. c) Balance tube. d) No Cats. (Yes, it's pretty ferocious sounding) 

8) External oil-cooler mounted in front of the A/C condenser. ... 

Marc R." 

<Is this the ultimate blown 928 engine or what?   Maybe, see Vol.2 for the Callaway 928 TT also!  Ok I hear all the fans crying for polished valve covers - we need something to vent our jealously at! > 



* Rotrex Super/Turbocharger - Scanpower Tuning Aps, Valby, Denmark, 


* Nitrous Oxide Systems Inc. (NOS) 1-714-821-0592 

* Nitrous Express - see Excessive Motorsports 1-816-224-8849 

* The Nitrous Works - 1-706-864-2206 

* Engine Management

Want the ultimate in tunability?  Check these companies and open that wallet up wide!

-  Electromotive's TEC II

-  Motec

-  Haltec


* Engine conversions 

" Hello, 

I received this from a friend of mine. I think you 928 guys might find it interesting. I'm not on this list, so send any replies directly to me (or to the author) 

Barry "

> Hi guys, 

Well we tested yesterday at Pocono, and it was fun. The day started out with me arriving at Pocono International in the Cobra, with the team car running late, and rain starting to fall. It was a mess getting the credentials together to gain track access, but there I was; alone in the pit lane, rain falling, and starting to wonder just what the hell was going on. When the transporter arrived, my questions were answered. The Baci Racing Bodymotion Car and Driver One-Lap of America Porsche is magnificent! Full credit must go to fabricator Mike Bavarro for an incredible piece of workmanship. Bob Mazucuola stood by like a kid with a new toy, just dying to get this thing running, and Sam Wolkoff was just as anxious. We backed it off the trailor, and there it sat for my appraisal. The body is white, and fully custom. Strosek panels are perfectly aligned, and the attention to detail is evident throughout. Lexan windows, lightwieght hood, Fikse wheels, Pirelli P-Zero tires (bigger than some apartments I've lived in). Beautiful metal fabrication in the trunk covers a thirty-gallon ATL fuel cell, which peaks out from under the rear valence. Big chrome dual exhausts exit the rear bodywork, heat shielded. The interior has Recaro seats, roll bar, sound system, brake bias adjustment and the like. The car is comfortable, as needed for a non-stop cross-country jaunt. Under the hood is the meat of this project. A Donovan Chevy engine dynoed at 560bhp. The install was as clean as could be, with special Porsche valve covers made to fool onlookers. The headers are hand made and are sculptures in themselves. Bavarro suited up and anticipation was running high. The engine turned over immediately. The car rumbled out onto the wet track and some shake down laps were completed. Minor adjustments and back out. We did this for the afternoon, dialing the car in, and switching drivers. The thing just ran like stink all day. Fast, reliable, and fun. We'll test at the Bridge again on Wednesday. 

> "How fast you want to go depends on how much you want to spend." > 


For more hybrid information see 


* (manual trans) stock knob pulls off with some coaxing 

* use cut-off tool or hacksaw on rod to desired height. reinstall stock knob (aftermarket knob will require some jim-foolery to fit on).   Another hot tip is to puchase the GTS-spec knob/boot combo as the handle is larger and more ergo shaped than before.  These knobs are in short supply from Porsche and probably will not be produced in further quantities.   Dark blue is n/a and as of 4/98 there are still some black ones in stock.  Yes I have one on order and will try to get it recovered by Alan Gun Leather Accessories in Dark blue to match my interior. 


* the factory way 

Install the short-shift rod from the '89 - '91 928 GT ! Note may not fit all years, check hole spacing... 
 * Phil's tipOn manual cars, the forward shift rod pivots by way of a  plastic cup on the rod end, which is then mounted to a metal ball attached to the torque tube.  Needless to say, plastic wears out and when the the cup wears/fails you are left without the ability to change gears.  Not good at high speeds.  To provide backup safety I simply put two large hose clamps together and wraped it around the shift rod and torquetube.  So if/when  the cup wears, it will not pop off due to the straps!

This is also the hot tip on how to get a new cup back onto the metal ball - it's a real tight fit, don't forget to moly lube!

Marc Reveil re-engineered the entire cup arrangement and fabricated his own connector joint.  If you ask him real nice, maybe he'll make you one also? 

Below is a shot of Alan Ng's custom interior - hey Alan, shorten that shifter wouldja' ! 



* replacement throttle valves to allow 1st gear starts always (4-speed Daimler-Benz AT) 

(all MB autotrans start in 2nd unless kickdown switch activated by mashing the throttle) 

1st. gear start valve bodies, Precision Auto Designs, Campbell, CA. (800) 222-7253 

"Tim, the Mecedes-Benz unit in your car is controlled by and can be adjusted with A. Modulator Pressure B. Working pressure C. Vacuum from engine. There is also something called a "Bowden Cable" that is adjustable for the kickdown engagement. Your local M--Benz dealer can help you. They have equip. that connects to the trans while test driving that can read out the working pressures/modulating pressures/etc. and tell you whats happening. Barring a scud missle attack on your car by angry too-slow neighbors from Texas, this should turn out to be a adjustment by the dealer. I would not suggest that your local "transmission shop" work on your MB auto. Let a MB dealer or Porsche Dealer look at it. They have the test equip to isolate and take care of problem. Remember to service trans. each 30K miles, and "Jack will stay a happy boy.  R.S. "


Here's a less expensive and novel approach to control 1st gear: 

" ... make the mod that I "fathered" and posted... 

" Run a momentary contact, SPST foot switch in parallel with the electric kick-down button that resides under the gas pedal and mount the switch on the dead pedal. Cost ---> $10 



84 928 S Guards Red 

79 928/383 Hybrid 5-speed Silver " 



* early double disk vs. later single disk 

* earlier cars can be 'upgraded' 

* later cars can be retrofitted 

* (?) CenterForce (at least check website for other info) 



* three types of struts from factory, Boge Bilstein & Koni, check before swapping as may need adapters/perches especially if you're adding adjustable height collars.   Some have success by flipping the perches around, call it the lo-tech/lo-buck approach, I call it ingenuity!

* progressive rate, lowering springs available from Eibach (as developed by Kim Crumb, PCA 928 Technical guru and racer) 

* linear rate + koni adjustable shocks (as developed by Devek Performance).  

*  Koni adjustable shocks from 928 Specialists

* swaybar 
   - Weltmeister  28mm front bar 
   - Devek Performance 32mm front bar (two styles, lightweight or heavyweight  depends on application, please contact on your application) 

* early balljoint caveat - pre' 84 cars featured aluminum balljoints which have been known to fail. They should be upgraded to newer steel type. See your Porsche dealer or shop. 

*  factory-spec:  Many have found success by installing the suspension from the GT model - stiffer sport springs and shocks. 

*  another 'quick tip' involves putting the front springs (500 lbs) on the rears, custom springs on the front and using adjustable spring collars to set ride height and corner balance. 

* corner balancing: 

>>from Porschefans post see

" I'll be working on my suspension this weekend, including corner balancing. I've lined up a set of scales, but I don't have a clear idea of how to corner balance. Can anyone give me a basic tutorial? "

" I'm confused about how to adjust the weight without also screwing up the ride height. Won't I end up with a car higher on one side than the other? Or are the adjustments for weight balancing small in relation to ride height? << 

" First you must set the ride height to where you want it. Then the car will probably need corner balancing, as there is no way to know if two diagonally opposite ends are supporting most of the weight. 

From old posts of mine : 

Now the car must be balanced. On most cars without chassis problems or bent sway bars, there is a simple method of getting the car set to baseline levelness. Simply disconnect one end (or the 2 center mounts if easier) of the sway bars and place something in the driver's seat to approximate the driver's weight. Then try to re-attach the sway bars and you will see if one side is higher than the other because the mounts will not line up. Adjust the sides until the bars line up and you have a basically level car with no swaybar pre-load. But it is possible to have more weight on two opposite corners of the car with this method. Try jacking up one end of the car at the center-line and see if the car comes up straight and both wheels leave the ground at the same time. If so, you are probably OK. If not, or if you are a serious competitor, you should corner-balance the car. The purpose is not to get the left and right weights equal, but the proportions equal. The left side of the car almost always weighs more than the right. Fred Puhn's book "how to make your car handle" has a good explanation of this procedure, or take your car to a good shop that understands the concept. For example, if your right side weighs 1200 and the left 1300, with a 40/60 weight distribution front to rear (mid '70s 911) then the right-front should weigh .40 x 1200 (480) and the left front .4 x 1300 (520). 

The Puhn book (How to make your car handle) says "the left and right sides of the car may not have equal weights, because the CG may be offset to the side. It is only the front-to-rear RATIOS that should be identical" (copyright Fred Puhn) To quote Puhn again "if the front end of the car carries 40% of the total car weight, then the left front tire should carry 40% of the LEFT-SIDE weight." (Sorry Fred, please don't sue me). Bruce's book (old one, page 174, top right) says exactly the same thing. 

When you find which diagonally opposite corners have too much weight (they will each be high by the same amount if you calculated right!) you should lower the 2 heavy corners, and raise the two light corners slightly, all by the same amount, then drive the car and measure again. 

<<. According to at least one local shop (Autobahn = Performance) you can end up with a car that doesn't look level after the = corner balance. Their recommendation is to corner balance before the = track and level it afterward if you want a level street look. They also = suggested you weight the car with driver and fuel weight that will match = what you will have at the track. >> 

If you set the car level first, and always adjust all 4 diagonally opposite corners to correct corner weights, the car should stay level. 



* suspension settings: 

"One quick question for you before I go Adam, and one I seem to have asked |countless times here to no apparent avail and that is did you manage to |make a note of the suspension settings (alignment, caster camber etc.) |after fitting? I am having a devil of a job sorting out my geometry and |would be eternally grateful for any adice you might give (Especially as |regards camber as the car feels great though I fear for the life of my |tyres! "

"OK brought my suspension settings in today. 

My current settings vs. 83-95 928[S,S4,GT,GTS]range 
 fr caster: 4 deg 50min 3 degrees 54 min to 5 degrees
camber: -1 degree 36 min. -0deg 20min to -0deg 40min
toe(ea side): 0deg 1min 0deg 5min to 0deg 10min
rear camber: -1deg36min -0deg30min to -0deg 50min
toe: 0deg 0min 0deg 5min to 0de 15min
As you can see mine are all out of the specified range except Caster. I would not recommend mine unless you are autocrossing/tracking the car as much as you use it on the street. 

Hope this helps.. Adam" 


* Devek big brake upgrade packages ie. S4 & GTS kits 

* Devek lightweight rotors 

* gas-slot front rotors and cross drilled rear rotors only. don't mix the rotors up - proper side & direction is critical. 

* fluid recommendations - see Red Line & caveats on 928's shared brake/clutch fluid system 

* pads see HAWK Brake at (as used by 928 racer Kim Crumb!) 

Choose your pads wisely! Race pads may not heat appropriately for street use & when at proper operating temperature may (properly) transfer enough heat to boil your old brake fluid with disastrous results. Or they may be so hard as to cause undue rotor wear (not to mention noise!). Best to consult with the manufacturer to review your intended application. 


* AIR - American International Racing 1-818-504-2500 

* Strosek wide body & projector beams 

* NR Accessories 


Euro cars were equipped with 8" 'Big Bosch' lenses, while US spec cars were straddled with less efficient 7" sealed beam headlights. One of the most worthwhile upgrades is change over to the better lights & lenses. Though not a cheap conversion (8" lenses and bulbs quoted at $250 for one set) the 928 was designed for these lamps specifically and they will do wonders for your nightime driving safety. 

A lessor known and cheaper upgrade comes from all places, the pages of the JC Whitney catalog. Therein is listed an imported 7" lead crystal lens and all sorts of upgraded H4 bulbs (I'm using this exact setup with 90/130 watt H4's on the '84).  These higher wattage bulbs usually are from the UK and my next set will be 80/100's 9004 bulbs for the GT.

A more recent phenomena is the availability of 'blue ion' and 'gold ion' upgrade bulbs not unlike the latest 993.   True gas discharge lights will prove costly and probably can't be retrofitted to the 928 without extensive headlight bucket mods.  Some new, blue and/or green bulbs prove to be just that, standard halogen-spec dipped in blue dye - caveat emptor!  Another reason to stay away from colored bulbs is most won't be DOT-approved nor will you like the attention they get from passing patrol cars. 

<author note: please remember to keep your lights aimed properly and to use higher wattage lights with prudence so as not to blind oncoming drivers!> 



Seats, harnessess and steering wheels.   Stock wheels can be replaced without needing a wheel puller.  Hub extensions are available as the signal stalks can end up too close to the wheel on certain flat wheel models.  Dished wheels are another option. 

Airbag-equipped 928s please be careful performing any mods.  I have not tackled this project yet but plan to.  As a hint, to fool the airbag brain, I plan on bridging the airbag leads with resistors to trick it to think the bag is still loaded.  More than likely I will leave the passenger bag in place.  Dangerous work - YMMV!   Use extreme caution handling and storing the bag and exploisve trigger, serious burns and injury can result from mishandling! 

Recaro 1-800-873-2276 

Sparco "The Choice of Champions" 1-800-224-7223 

New Brey-Krause fire extinguisher mount , see OG Racing online 

(see also SpeedWare Motorsports

World Upholstery   -rug kits 


Missing rear luggage cover?  There is a new company offering remanufactured covers for $150!  This is a far cry from the $1,000 for a new one.  Also see 928 International these were $295 at the time of this writing.

*  Rollbar 
see Autopower 
see 928 Specialists
see Devek Performance new custom design 

* Harness bar  
sometimes, homebuilt units will appear in the classified section of Panorama 
Vendors working on it too 

* offset info - do not violate or suffer tire rubbing and possibly adverse handling.  See the archives at for info on crimped fenderwells for additional clearance.
Ray Jang demonstrates how to measure backspacing with a straightedge across the wheel rim, against ruler on inner wheel hub mounting surface...



dp Motorsport wheels 

Hart racing wheels 

Kinesis - these are really nice!

OZ Racing - are these "phat" enough!?!
I thought so - I bought 'em!  17x9 front & 17 x 10 rears... modular
rims as spec'd by Kim Crumb for Ray's ex- 928.  


Wheel Enhancement The most knowledgeable non-factory source of information, with quite fair prices for wheels of all levels of zoom-osity.  Update your older 928 rims - trade in program 

Tire Rack has a wide selection and good prices on tires, but may not know about the specifics of 928 applications... 

Discount Tire Direct ( is less useful than Tire Rack as a source of information, but frequently beats them on price. 

   Going Racing?   

Check out RACER WHOLESALE 1-800-886-RACE 

See Summit Racing Supplies 

See Pegasus Racing Suppllies 

See Truechoice Racing Supplies 

See OG Racing online 

Check out The Racer's Group 1-707-935-3999 - helmets, harnesses, race suits and more! 

Battle of the Imports - "The Finest Import Drag Race In The Country -- Period." AIRA Motorsports 1-213-980-8966.  I was usually the only 928 at the strip.  Maybe this year will be different? 

NASA - National Auto Sports Association, Pro Racing  
Autocross, enduros, bracket racing, instruction - highly recommended! 

Pony Express 100 Road Race, Nevada: 

" The Pony Express is for novice and experienced racers alike. There are speed classes and safety requirements that you can easily meet without any problem or prior experience. Although it will be a walk in the park, you could start out in the touring class, where the highest average is 110 mph (I think?). All that is required is a helmet and a vehicle in excellent condition (i.e., no leaks, good condition OEM belts, properly rated good condition tires, etc.). I think they might even give an exemption to 928s (as they do to Corvettes) for a roll bar up in some of the higher classes, but you would definitely have to have five-point harnesses to go higher than 110 average speed. 

They hold a practice session on Friday for those who have never competed before (and anyone who wants to "shake-down" their car). That gives you a feel for what you and your beast are capable of doing on race day. You can pick your speed class *after* the practice session, so that you are sure that you will be comfortable with the speeds you will be reaching during the race. 

Give them a call if you are interested...their phone number is 619-440-6043, ask for Sherri Ward and tell them we sent you!!! We would *love* to see you's not just the race event, it's a whole weekend of car-loving fun. Nice people, good weather and cheap motel rooms...what could be better than that? :) " <reposted from Devek> 


Silver State Road Race, Nevada 
Thank you for your interest in the Silver State Classic Challenge 
series of  Open Road Events. 

The dates for our events in 1998 are as follows: 

Nevada Open Road Challenge...................April 30 - May 3 
La Carrera Classica (Ensenada Mexico).....July 23 - 25 
Silver State Classic Challenge....................September 17 - 20 

The Nevada Open Road Challenge and the Silver State Classic Challenge 
events are both run on State Route #318 in East-Central Nevada from the 
Towns of  Lund to Hiko.  The course is 90 miles in length, all on a state 
maintained public highway, with straight-aways up to 11 miles in length. 
The Nevada Department of Transportation closes the roadway to normal 
traffic for the duration of these events.  These events are sanctioned and 
insured by the American IndyCar Series. 

                                         THERE IS NO SPEED LIMIT! 

Anyone can enter this most unique automotive event who is at least 18 years 
of age with a valid driver's license and who brings a roadworthy 4 wheeled 
vehicle.  You pick the speed that you would like to average from 95 mph up 
to 130 mph.  If you have entered this event previously, or if you have a 
recognized relevant competition driving license, you may select an average 
speed up to 165 mph. There is even an unlimited class where speeds are in 
excess of 220 mph for the most experienced drivers! 

There are special competition driving classes in Las Vegas on Thursday 
before the event as well as practice and qualifying at Las Vegas Motor 
Speedway.  All first time drivers are treated to special attention and 
instruction throughout the weekend to ensure that they enjoy everything 
these events have to offer. 

After four days of driving, receptions, a parade, a car show, and the 
fastest event held on a public highway in this country, there is the awards 
banquet at the Showboat Hotel & Casino in Las Vegas.  1st, 2nd & 3rd place 
trophies are awarded in each speed bracket plus many other awards such as 
Rookie of the Event. 

These events are four days of action packed fun, the most fun you can have 
in a car with your clothes on. 


For more information, check out our web site: 

To get a video of our 1994 event as aired on ESPN2 go to

Silver State Classic Challenge, Inc. 
P.O. Box 420 
Ely, Nevada 89301 
E-Mail us at: 

Closing note: 

Remember to have your car properly prepared and tech'd prior to entering any type of speed contest. You also need to be prepared by completing any medical exam or driver training / licensing required. Most insurance policies will not cover damage to your vehicle or it's occupants while participating in these types of events. A motorcycle helmet (M rating) is not acceptable - you must get an SA90 or better helmet (SA95's available now) which provide protection from multiple impacts, fire retardance, etc. If rules allow racing harnesses with stock seats, observe all race and manufacturer instructions for mounting properly to avoid injury in the event of a crash. For further details, contact the race or club organizer for their specific safety requirements. 

I hope I've whetted your apetite for more!  This section is by no means the be-all/end-all of 928 modifications - those S4 trucks from Denmark prove that.  I've only scratched the surface here.  Your particular car must be setup for your own driving style and intended use.  When you're ready, please do contact the shops and manufacturers above for their expert experience and guidance. 

See you at the races!  

ps. In case you were wondering, the lead photo features a dual-turbo 928 engine slated for marine use! Thanks to the olemiss site for use of the photo!