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    Thread: Building the Ultimate 1983 Rabbit GTI (vw mk1)?

    1. 01-19-2013 02:57 AM #1
      [Editor's note: I realize that using the word 'ultimate' in this forum heading is over stating things. The only possible 'ultimate' 83 GTI would be to go into a time machine and go back to 1983 and buy a totally stock example and drive it around. But that isn't possible and you simply can't get NOS shocks and springs. That said, you could get damn close to the original stock feel with a great deal of care and attention to detail. And that would be the modern equivalent of the Ultimate GTI. In defense of my use of the word 'ultimate', I was an original GTI owner, and I was wrenching on it from the day I bought it, and racing it, like countless other GTI owners have done over the years. These cars were meant to be modded and raced and that is the position I have come from: to keep the spirit of the original car, in a modified, but totally streetable sense, without a huge turbo system or other 'over the top' change in behaviour ....]

      I want to let the readers of vwvortex.com know that I am deep into a new project of significant personal meaning to me as an original owner of a 1983 GTI that I spent countless hours building up over the period of 1983-87. I have acquired another US spec GTI of the same build date (Nov 82) and have engaged Techtonics Tuning and a host of other vendors in the task of building the ultimate streetable GTI while keeping true to the original car.

      You can follow this project at: http://derekspratt.com/HTML/Automoti...als_Specs.html

      You can also comment on this project either on this vwvortex thread or on the blog on my web site - I want your feedback and input as this project progresses.

      We are trying to build a car with excellent street driv-ability and manners, a car that looks stock inside and out, but takes on a new dimension when you look under the hood or under the car. Think normally aspirated mk3 ABA block with a 95.5mm ABF stroker crank, custom length rods, and 83.5mm 12:1cr pistons married to a 16V 9A head that has everything done to it (oversized valves with 5.5mm stems, 288 solid lifter race cams, lots of porting, etc) - but with a focus on balancing mid-range torque and peak hp. And an AT Power ITB DTH intake system - all adding up to a targeted 240hp at or slightly above 8000rpm, plus a custom radiator, a trick 020 AGB 2Y (mk2 16V) close ratio trans with a Quaife diff, and many many more goodies including a dry flow nitrous system, all controlled by a Holley HP EFI ECU. And the suspension system, brake system, and everything else is new, top drawer, and streetable as well.

      So tell me what you think. I am in the middle of cutting out the rust from the project car, and starting to weld in new sheet metal, while I carefully design a whole series of stiffening elements to make this car structurally tight and safe at speed. The engine is coming together quickly, the trans is finished, the suspension is 'in hand' and the braking system is not far behind. But there is a ton of chassis development, bodywork, paint, interior work and final assembly ahead of me.

      Here's to all of the vw mk1 fans out there that want to build cars that embrace some new technologies while keeping true to the original car in most ways ...

      Cheers,

      Derek
      Last edited by Derek Spratt; 11-21-2015 at 03:27 AM.

    2. Member
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      01-19-2013 08:11 PM #2
      Opinions are like a$$holes, everybody has one, here's mine:

      IMO what you're describing is clearly superior, has been done in variations many times, and would not be "true" to the original GTI.

      Just the addition of more valves betrays the simplicity of the original concept. Build up a Techtonics 8 valver, those sorts of mods, and enjoy an "improved" GTI that is still a GTI: a little lacking in everything and more fun than the sum of its parts suggest it should be, which was the point.

      But OTOH, do as you wish and enjoy

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      01-19-2013 09:05 PM #3
      Sounds like a delightful midlife crises ill watch Vr eaters are always entertaining

    4. Member justin_6649's Avatar
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      01-20-2013 12:48 PM #4
      sorry man but this is definitely gonna ruin the inside of the car

      http://derekspratt.com/Images/Automo..._VZ401_540.jpg

    5. 01-20-2013 04:43 PM #5
      I thought long and hard about building another 8v motor but I was always dreaming about a 16v head, even back in 1983. The 8v heads just don't flow that well, not being cross-flow, etc. The benefit of an 8v head isn't just to be period correct, which would have been nice, but it would have kept the mid range torque feel of the mk1 GTI more accurately represented. We are going to work hard to make the 16v engine torquey though.

      In regards to the audio control unit, the idea is to have access to bluetooth for celphone use, which is the law in BC where I live and also to allow me to connect my smartphone as the source of music - which is my life these days. By having all of this functionality hidden in a pop-up LCD unit that collapses to a std 1 DIN faceplate, that is ideal for me. I can leave it hidden 90% of the time, and only need to pop up the LCD when programming is required.

    6. 01-22-2013 10:57 PM #6
      I'm really digging your plans for this one. Take everything that the mk1 gti was (the best real driver's car ever designed, IMO) and build everything to the highest level. 16v motor tuned for low-end power, same gear ratios (with a slightly higher ratio r&p to accomodate the increased power), less unsprung weight, stock unassisted steering, stiffer springs, dampers and chassis, and it will be a blast to drive! Same basic design and balance, just better everything.

      The 16v motor should be fine and I can't honestly think of a better choice (aside from maybe a super-built, all-motor 8v, which would end up being more expensive to get the same power - and probably end up having a very similar powerband to your 16v), I think the 16v gets a bad rap from its use in the heavier mk2 models, where the rush of extra power at the top end made it feel less torquey in that car. In any event, its going to be head and shoulders above a turbo'ed 8v torque-wise.

      I think your biggest challenge will be getting the suspension dialed in where you want it, but I think you're on the right track with starting out with no front swaybar. Might want to plan on moving the battery and as much other weight to the rear from the start, every little bit helps.

      Good luck, I'll be watching this one for sure!

    7. 01-23-2013 03:00 AM #7
      bpetry, thx for the kind words of support. I think you nailed it but even though my goals are lofty I am nervous about all of the design/spec decisions (similar to building a new home), and not knowing whether it will all come together to create that pure driving experience that I crave.

      I know I can create a stiffer chassis that is lighter than the stock GTI, and in some areas it will be a necessity, not a luxury, as having sturdy engine and transmission mounting points with this engine will be a must for reliability/safety alone.

      The folks at German Transaxle helps me spec the 020 2Y close ratio Scirocco 16V transmission. We decided to not mess with the stock ratios or final drive so it really should be as you describe.

      Josh at TT has been amazing to speak with. He is really hand holding me on many aspects of the vehicle design/implementation as he has put together so many mk1s over the years covering everything from street, strip, road racing and off road racing applications. And he's had his own cars. So he steered me in the direction of the engine block, crank, rods, heads, valve-train components, cams, everything in the quest for street manners, and broad torque more than HP. He's pumped about the potential with the engine as he is using every last tip and trick he's used and he gets to plumb the intake with the awesome AT Power DTH TBs. He isn't convinced that the H&R race springs are the best move but I'll just have to drive it and start to tune it from there. The struts can be custom valved by Bilstein and I can always move down one level to the H&D sport springs or add a front sway bar. My last GTI had a pretty firm ride and had huge sway bars so I'm betting I'll like the ride ...

      The choice of a bigger 16V engine is really due to the fact that I always wanted more from my 8V than we could get with head/drivetrain upgrades alone. I love free revving engines and I just know that 200+hp streetable hp in a stiffened mk1 chassis will be true to the original GTI's character, only better. But this is a very personal thing and I totally respect other people who say that I have given up a bit too much of the originality of the 1983 GTI ...

    8. 01-23-2013 03:01 AM #8
      I posted a web site project update tonight covering the start of the chassis preparation and fabrication ...

    9. Member justin_6649's Avatar
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      01-23-2013 10:27 PM #9
      Quote Originally Posted by Derek Spratt View Post
      In regards to the audio control unit, the idea is to have access to bluetooth for celphone use, which is the law in BC where I live and also to allow me to connect my smartphone as the source of music - which is my life these days. By having all of this functionality hidden in a pop-up LCD unit that collapses to a std 1 DIN faceplate, that is ideal for me. I can leave it hidden 90% of the time, and only need to pop up the LCD when programming is required.
      to each their own i guess, i just bought an original radio because i found a nice new uncut dash bezel. i dont even have speakers in the car! cant wait to put it in, good luck with your build

    10. 01-24-2013 01:43 PM #10
      Oh, I am totally jealous. The next time you find a clean dash and/or radio, I would love to buy it! One option for me would be to hide the bluetooth radio in the glove compartment. I also have the Holley Dominator ECU LCD panel which can be unplugged - it is a more convenient interface for programming the ECU and pulling up virtual gauges for tuning and monitoring purposes than having to use a laptop PC. Another thing to hide out of the way when not in use.

      I would actually love a totally stock 83 GTI but it isn't possible. Too many parts that would need replacing that aren't available OEM/NOS.

      The original 8V motor and CIS system with the early emissions control system was really messy and very hard, even when new, to get to run perfectly. By 1987 my GTI was already running rough and had some issues with the fuel control system. I am totally cheating by using a self-learning ECU with a wideband O2 sensor. It takes all the work out of programming and keeps the car running optimally. And all of the complexity of the mechnical CIS system and early emissions control systems are gone - only the Cat converter will remain (I do want to run clean).

      Best of luck with your car as well.

    11. 01-24-2013 02:36 PM #11
      with so much superior and expandable technology available, why use a holley ECU?
      TDI | GTI | Type 1 | PVW 02/09

    12. 01-24-2013 07:03 PM #12
      You may be thinking of the old Holley TBI systems. This is the new Dominator ECU, which, to my knowledge and considerable research (as well as my prior experience designing ECUs in the late 1980s - see my web site) is the most capable and intelligent system on the market today. It is certainly the most expensive with the basic ECU costing $1600 and the wiring harness, sensors and LCD unit more than doubling that cost.

      But what you get for the >$3000 is a vastly flexible, programmable system supporting up to 24 injectors, 4 stages of nitrous (progressive, linear, fixed, etc.), dual wideband O2 sensor support which enables full self mapping/tuning to any desired A/F ratio at cold/warm idle, part throttle and full throttle, etc.

      Check this link out for more info: http://www.holley.com/types/Dominator_EFI_-_ECU.asp

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      01-24-2013 07:12 PM #13
      all wheel drive. mid engine. 225hp 1.8t
      mk3 gti

    14. 02-08-2013 08:16 PM #14
      I just completed building an innovative frame to allow me to rotate my car in my garage so I can work comfortably on the underside of the car ... photos and videos at:

      http://derekspratt.com/HTML/Automoti...2_Chassis.html

    15. Member g60vw's Avatar
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      02-09-2013 03:27 AM #15
      First of all, good luck on your build.

      I also had dreams of building a torque monster 16v, 95.5, ABA block and rods, 9A head and mild cams but when I was done it still drove very similar to the 1.8 16v I was used to. Nothing like an 8v. I spent a fortune, and really didn't have as much to show for it as I had hoped. I know that tuning is my last final hurdle, but I have to say be warned. If you haven't really dug in and committed to the 'valver, consider building an 8v. Tall block, TDI crank, 11-1, big bore, the whole 9 and keep the counter flow head, albeit with big valves and real PnP and it will do 150+whp with ITBs and a professional tune. Plus, when you whip VRs and mk4 kids, you can say, "it's just an 8v."

      For inspiration, check out this thread:
      http://forums.vwvortex.com/showthrea...no+vindication
      Quote Originally Posted by wilm13 View Post
      I refuse to say anything but A1, A2 and A3. As far as I am concerned VW stopped making cars after that.

    16. Member g60vw's Avatar
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      02-09-2013 03:46 AM #16
      So I went to your page and see that you are well on your way to going 16v, no biggie.

      Since it appears that you have a hefty bankroll the only changes I would suggest would be to source a 6 spd O2O using the original 2H gears plus a .75 or .71 6th and retain the 3.94. That is the key to why the early GTi's were so great, the immediate acceleration. While we are on the subject of transmissions, look into USRT and their shift linkage kit, full rod end conversion replacing the factory plastic junk and add that amazing bearing shifter base from Jarod at SCCH, you will not be disappointed.

      Also, get the quaife quick ratio steering rack, it adds some effort, but the turn in response is amazing. I feel it's one of the better things I've done with mine.

      The only other thing would be to replace the head unit with a 3 pack of gauges and move a single DIN to the glovebox for your tunes. You'd keep the modern convenience of Bluetooth etc, and the interior would stay looking simple and correct. Otherwise, please continue on with this project and admit to no one what you spend in the end. Maybe you too can join the 5 figure club at TT. :-)
      Quote Originally Posted by wilm13 View Post
      I refuse to say anything but A1, A2 and A3. As far as I am concerned VW stopped making cars after that.

    17. Member Cushy's Avatar
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      02-09-2013 05:04 AM #17
      Quote Originally Posted by Derek Spratt View Post
      You may be thinking of the old Holley TBI systems. This is the new Dominator ECU, which, to my knowledge and considerable research (as well as my prior experience designing ECUs in the late 1980s - see my web site) is the most capable and intelligent system on the market today. It is certainly the most expensive with the basic ECU costing $1600 and the wiring harness, sensors and LCD unit more than doubling that cost.

      But what you get for the >$3000 is a vastly flexible, programmable system supporting up to 24 injectors, 4 stages of nitrous (progressive, linear, fixed, etc.), dual wideband O2 sensor support which enables full self mapping/tuning to any desired A/F ratio at cold/warm idle, part throttle and full throttle, etc.

      Check this link out for more info: http://www.holley.com/types/Dominator_EFI_-_ECU.asp
      What about Motec or Lugtronic and how does the holley system compare?
      Quote Originally Posted by SVT2888 View Post
      The car scene, much like the music scene, has a lot of genre's and even genre's within genre's. But, like those who call themselves real music fans, if you're a real automotive enthusiast you can find something in every genre that you like.
      Quote Originally Posted by vento86 View Post
      Rip the ebrake. Neutral. Get bitches
      Function is the form.

    18. 02-10-2013 04:31 PM #18
      I really appreciate your posts, especially the 8V info. I am impressed with what can be achieved with a well built 8V motor. One of the things that I wanted to work with was ITBs and felt that the 8V head would not allow me to fabricate a cold air intake (not enough room) and the 16V cross-flow with intakes at the front was a clean solution. Anyway, I am thinking about whether a future experiment might be to swap out the 16V heads with an 8V setup ...

      Your other suggestions are equally appreciated. I have heard that the USRT shifter is very hard to get setup correctly such that you get clean, precise shifts. I was going to go that route but Josh at TT suggested that I start with their kit. I do want to explore this further and it isn't a huge $ item. Maybe I can try both kits.

      I was worried that the fast ratio steering box might be a bitch in the parking lot. But if it really makes the driving experience that much better, well ...

      What is your view on bushings, engine/trans mounts, etc? Do you believe that HD rubber mounts/bushings are better? The SCCH parts are very trick but I worry about harshness, vibration, etc. - ruining the driving experience on the road ...

    19. 02-10-2013 04:35 PM #19
      I can't comment on the Motec or Lugtronic systems but will research them. I have posted detailed info on the Holley system on my web site. It is almost overkill with all of the system capabilities and options. I wanted progressive Nitrous dry flow management and also loved the wideband O2 sensor support which allows for precise control of A/F ratios.

    20. 02-10-2013 06:13 PM #20
      Quote Originally Posted by Derek Spratt View Post
      I can't comment on the Motec or Lugtronic systems but will research them. I have posted detailed info on the Holley system on my web site. It is almost overkill with all of the system capabilities and options. I wanted progressive Nitrous dry flow management and also loved the wideband O2 sensor support which allows for precise control of A/F ratios.
      without a MAF how does it meter the air for the "precise A/F ratios"?

      You'd be much better off with a system like Motec, Haltech or ViPEC running a map based tune.
      TDI | GTI | Type 1 | PVW 02/09

    21. 02-10-2013 11:30 PM #21
      A common alternative to mass flow sensors (MFS) is to use a combination of throttle position (TPS) and manifold absolute pressure (MAP), plus an atmospheric pressure sensor for altitude correction. Some race only cars just use TPS (this is called 'alpha N') but this only works well for full throttle conditions and consistent atmospheric conditions. The wideband O2 sensor provides feedback to make any on-the-fly corrections to maintain the target A/F ratio.

      The difference between a typical narrow band O2 sensor and a wideband sensor is that the narrow band sensor only can accurately detect an A/F around 14.7:1 (so called stoichiometric conditions where theoretically all fuel and air is perfectly combined to create nothing but H2O and CO2 in the exhaust) by essentially switching from a low voltage output to a high voltage output at this point, while the wideband sensor provides a fairly linear voltage output for A/F ratios from as low as 11:1 all the way up to 17:1.

      The way the Holley EFI system works is that it relies almost entirely on the wideband sensor during 'auto learn' mode and it programs the injector PW settings based on target A/F ratios for different TPS settings. During normal operation, the TPS and MAP signals are used to 'look up' the injector PW values - the O2 sensor is a fairly slow feedback loop so it is only used for after-the-fact corrections.

      Mass flow systems, while common on street cars, are not ideal for high performance engines. MAP/TPS systems are more common on high performance engines for a variety of reasons: throttle response, lack of intake system restrictions, etc.

      Since I am using individual throttle bodies I need to create a common vacuum plenum that each TB taps into for both the MAP sensor as well as the brake booster.
      Last edited by Derek Spratt; 02-10-2013 at 11:34 PM.

    22. 02-10-2013 11:32 PM #22
      BTW, as a point of reference I am an electrical engineer and designed a number of aftermarket EFI systems in the late 1980s and 1990s and have spent a lot of time fooling around with racing electronics over the last 30 years ... and I have written a number of articles in industry magazines on the subject. I am not an expert on all systems on the market but I do know my way around the theory and practice of high performance EFI systems.
      Last edited by Derek Spratt; 02-10-2013 at 11:42 PM.

    23. 02-10-2013 11:40 PM #23
      I spent the last week building the car rotation frame system and it is now working with the car suspended at 90 degrees. It was a lot of work but is already paying off. I managed to strip off the remaining suspension system components, front and rear yesterday and get going on removing the remaining seam sealer. It should take me another week to complete that nasty nasty task.

      The great news is that there is no rust on the rear torsion beam axle mounting points/studs. In fact the whole back half of the car is rust free in all critical areas. There are some holes into the interior floor, but I am starting to realize that I won't have to replace the complete floor boards - only the front portions.

      I have a problem to address where prior owners jacked up the car on the weak sheet metal and I will have to carefully re-shape those areas, but I am putting in 1x2.5" square tube connectors, front to back that will cover up most of those areas anyways.

      You can check out my web site for updated videos and photos. I'll continue to post more photos as the underside of the car gets cleaned up. The rear axle assembly was also cleaned up today. Eastwood's Fast Etch made short work of rust removal ...

    24. Member
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      02-11-2013 09:07 AM #24
      I have owned a stock GTI and a midly built 8v, but have never driven or ridden in a stroked 8v.
      I do own a stroked 2035 16v with ported head and mild Autotech cams. The current setup made between 165-170 hp. It wasn't the fastest thing but the torque was pretty good. You could light the tires up just by stabbing the gas in first gear on a roll. The car weighs 2020 lbs and 14.7's all day street tires. I have always dreamed of 200hp ITB engine. I look forward to watching this, and wish you all the best of luck in your build.

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      02-11-2013 11:23 PM #25
      Awesome website! Wish I would have read through it before I started my project. I can really appreciate what you are doing, it takes alot of work. Look forward to what will come of this

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