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Discussion Starter · #1 · (Edited)
The purpose of this thread is to give my take on the best way to put together a simple, reliable, relatively powerful Naturally Aspirated Vr6 car. I’m trying to make my explanations as simple as possible, so if anything is confusing, shoot me a message, and I’ll try to revise the thread as best as possible. The same goes for inaccuracies. I’m always learning, and I’m willing to bet there’s more than a few assumptions in here that are inaccurate, so shoot me a message.
I've got a goal to grow the VW performance aftermarket. There’s so much potential in many of these motors to go fast, cheaply. So, the the best way I can think to do it is by getting info out there.
Through the engine, this will more or less follow the path of air.
1. Air Intake(Stock-cai)
A Vr6 car is equipped with a stock airbox from the factory. It is popular to replace the stock paper filter with a K&N. This is nice as it can be washed and reused. However, it has been tested that a fresh paper filter actually flows better than a K&N. There are minimal gains to be had by cutting the lower portion of the box and grinding the webbing from the upper portion.
Cold air intakes need to be the type that goes down into the fender/bumper to be advantageous. Many have discomfort with the filter being so close to the ground for fear of sucking up water and hydrolocking. These intakes will make more power than a cut airbox, but I do not feel that they are a cost effective way to gain power until further modifications make the airbox increasingly inefficient.
Because of the nature of the stock Bosch Mass airflow sensor(MAF), simply putting a filter or a ‘short ram’ intake onto the end of the MAF is not effective. This sensor requires a flow of air devoid of turbulence, which is taken care of with a ‘turn2‘ style cai. I lost a significant amount of power on a dyno going to a filter on the MAF.

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1.8t IAT(Intake air temperature) sensor-This has been proven to give 2whp on the dyno by Paul, need_a_vr6. The stock Iat sensor is closed element, and prone to heatsoaking in the vr manifold. The 1.8t sensor plugs directly in, and when wires are extended to a location that gets proper airflow, away from hot engine parts, proper Iat's are achieved. The ecu interprets this data, and gives a tick more ignition timing.
1.8t sensor:
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2. Upper intake elbow
This is not an overly problematic component. I have made 204whp with a stock upper intake elbow. The oem PCV valve is a problem. A PCV valve’s function is to vent positive crankcase pressure back into the intake, while restricting oil from passing through. This valve seeps a large amount of oil, and makes the vr6 motor a very dirty running motor. For this reason, it is important to routinely remove the elbow to clean it and the throttle body. Some choose to run a ’catch can’, which allows for crankcase ventilation, and catches excess oil from being cycled into the intake.
The only aftermarket replacement is the ABD big bore intake. These sell for entirely too much in the classifieds, but they do eliminate the banjo section. Gains are minimal. I would not recommend doing this as a preliminary modification, and it's a stretch to be worth it in any situation.
3. Throttle Body

The oem throttle body is not overly problematic. The obd2 throttle body(96-99) is slightly larger than the obd1 throttle body. They cannot be simply swapped as the bolts are different sizes, and the TPS(throttle position sensor) is wired differently. I have read that the wires can simply be swapped around for the obd2 tps/tbody to be used on an obd1 car. Porting should be kept to a minimum, especially on obd2. A gutted, or ‘deramped’ throttle body oftentimes causes idling issues on stock engine management.
I ran the OBD2 TB on my car (on 95 OBD1 and standalone). I was using an OBD2 Schrick VGI at the time, which still has the port for the idle valve, so that wasn't effected at all. You need to use the full range tps on the OBD2 TB:

1 IAC +12v - not used
2 IAC ground (to ecu) - not used
3 Not used
4 Ecu to TPS +5v
5 TPS signal 0-5v to ecu
6 Not used
7 Tps ground
8 Not used

Pretty sure that's how I did it, but it was a few years ago.. check throttle angle with Vag-Com, if it's high at no throttle and low at high throttle swap 4/7.

The OBD1 computer won't like the OBD2's internal idle valve, so don't even try.

4. Intake Manifold
This is in my opinion, one of the most problematic parts of the VR6 engine. The stock intake manifold has an upper and lower portion. The throttle body inlet is about as restrictive as restrictive gets. It transitions from the circular throttle body to the flat plenum area with a steep ramp, and multiple internal parts sticking out directly into airflow. The plenum, or the open area before the runners is not a major problem in stock form, but the transitions into the runners are very restrictive. The plug wire holes are directly in the airflow, the dividers between runners are thick, and rigid in construction, and there are multiple internal bolt holes directly in the airflow.
Modified/aftermarket options
Ported lower intake This largely contributes to having a complete, matched intake and head. It doesn't really need a whole lot of opening/reshaping, but it can be smoothed, and mated appropriately with the upper intake and the head.
The 2.9 Manifold- In Europe, some vr6’s were 2.9l instead of the usual 2.8l. These had a different upper intake manifold in which the entire space under the manifold is used as a plenum, allowing for more airflow, and slightly more power band. Many choose to cut the middle channel from a stock 2.8 manifold in an effort to clone the euro 2.9. The important thing to remember here is that all 2.9 clones are not created equal. There is much work to be done in smoothing the dividers and transitions into the different runners. The throttle body inlet should be modified. Again, this is not something that should be a preliminary modification as there are parts further down the line that need addressing first.
These are of my ported 2.9 clone. The corner that restricts cylinders 5 and 6 is toward the left in the first picture.`
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Precautionary: In the stock lower intake manifold, there are ciruclar dowels that are designed to help the upper and lower manifolds seat together. Remove these and throw them out. Sometimes, they come out unexpectedly and go down an intake runner, causing valvetrain damage. Ask me how i know.

This dowel is in the lower right of this picture:
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Short runner intakes- In general, shorter runners and a bigger plenum promote a higher power band and less torque. That is, the majority of the car’s power will be shifted to a higher rpm given other components promote this. The basic short runner, ‘log manifold’ has been used to some success on n/a drag cars, but this is in limited numbers and accompanied with supporting mods such as large camshafts, and large diameter exhaust. The gains are difficult to quantify as this has only been used as ‘part of a setup’, and not simply an addition to stock.

There have been a few equal runner length short runners built custom. These are ideal as the runners in the intake compensate for the varying lengths in the cylinder head. With just an intake swap from a 2.9 clone to this type of staggered sri, i gained 30whp at 7k rpm, however, i lost 15ft/lbs of torque and a significant amount of hp through my midrange. Think of a more honda like powerband than a vr6 powerband. These gains occurred with no tune change, or cam change.
5. Cylinder Head
This is the root of the problems in this motor. This is a 15degree 6cylinder engine with staggered cylinders and one cylinder head.
The vr6 has a FLAT cylinder head. The majority of cylinder heads in the world have recesses in the block side called ‘combustion chambers’. This motor, with the head being flat, has the combustion chamber in the piston itself. On cylinder heads with combustion chambers, it is possible to ‘deck’ the head, removing material from the bottom of the head, making the combustion chamber smaller, and raising the engine’s compression. Raising compression adds power, but is not possible in this way, on this motor.
Head with combustion chamber:
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Flat Head:
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The engine functions as a 'bent' straight 6 in that There is one intake side, and one exhaust side to the motor. The camshafts are not in control of independent banks(intake/exhaust). Each cam takes care of intake AND exhaust, so the runners for intake and exhaust sides vary in length to reach their respective cylinders. On each side there are short runners and long runners, each carrying their own problems in terms of port shape. The varying length also makes the harmonic balance of airflow in this motor very difficult to master. In an ideal world, all intake runners should be the same exact length and volume, head through intake manifold. The same goes for exhaust ports through exhaust manifolds. The world isn’t perfect, we’ll work with what we’ve got unless you’re looking to build varied length runner manifolds, which have been done to great effect. However, for the purposes of this thread, that won’t be covered.
Porting- This section is really general, and possibly pointless. Some say that headflow can only be measured on a machine called a flowbench. Others say that headflow can only be tested at the track. So, i'll just give you some ways to look at it.
The best way to learn is to grab a spare head, and get at it. There is MUCH that can be done to shape these ports better. Again, I’m no pro when it comes to porting, but I can give a couple areas of interest.
For materials, I use mainly sanding rolls on aluminum and a straight die grinder. These can be found on Eastwood. The valves must be out of the head.
Intake ports should be a bit larger than exhaust ports, but not too large. Size can help flow, but maintaining a small enough volume to maintain air velocity is just as important. One way of thinking about a port is as a siphoning hose…in order to maintain constant, fast flow, it cannot have too much volume, nor can the volume change throughout. “Bowl” areas should be focused upon. This is the transition down to the valve seat, and where most losses on stock heads occur. Long VR6 ports are misaligned with the center of the valve seat. Short ports have waves in the walls that can be smoothed.
DON’T SIMPLY ‘GASKET MATCH’. This is changing one area of the port’s volume, and hurts flow. It is important that a port’s entrance not be smaller than the outlet that precedes it, but that does not mean that it is effective to ‘hog it out’. I put a considerable amount of work into the head on my race motor, and I’m nowhere near gasket size in most cases.
Mildly Ported short intake runner:
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Valvejob-This is how the valve seat is shaped. The smoother, or more cuts that are taken(3 angle, 5 angle, etc) the less restrictive it is on airflow. This is widely considered to be the most important aspect of performance headwork. Being a delicate, skillful process, this is something I trust a machinist to handle for me. I have made as high as 210whp on stock valves with a quality valve job.
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6. Valvetrain
There isn’t a whole lot wrong with the stock valve train(valves, valve springs, retainers, keepers, lifters). The main precaution to take is to upgrade to a set of performance valve springs, serving two purposes.
A. To prevent the spring from binding because of aftermarket camshaft lift.
B To keep the valve from ‘floating’, or hanging open too long, and being struck by a piston.
For Motors with aftermarket cams(except for low lift cams such as autotech 262’s) or forced induction, this should be looked at as a mandatory item.
Except in extreme builds, I don’t see a reason to upgrade any other component. Having a machine shop back cut stock valves offers some power, and what I consider a ’might as well’ if you have the head there.

It is debatable in my opinion whether bigger valves actually make more power. BVH are not worth all the hype and cost associated, especially dealing with a stock sized bore. There is a concept of headflow called "shrouding" that basically says when a valve is too close to the edge of the combustion chamber(pistons in our case), or cylinder wall, flow is restricted. The fastest 12v vr6's have stock size valves. I also believe that this is made more dramatic as a result of our head being flat. Google "valve shrouding" for more info. FWIW, dynos of some of the old school uber desirable bvh's have shown little to no gains over stock heads.

Titanium retainers are available to be used to lighten stock valve train, but I don’t feel that these are a good place to spend money unless again, you’ve got a highly built race motor, and looking to find that extra little bit of insurance against floating a valve(valve hangs open and gets struck by a piston) at 7500k rpm. The same goes for ‘lightweight lifters’, which are simply mk4 lifters.
7. Camshafts
There is actually a pretty good variety of cam profiles available for VR's. Most of them are very very small, which i don't really get, but i'll lay out the key players. These cams are listed by their advertised duration.(how many degrees the valve is held open for)
Autotech 262's: These are nice mild cams with a low lift. This low lift allows for stock valvesprings to be kept. This saves a bunch of time and money if you're not looking to get into paying somebody to tear into it. A slight shift in powerband will go on, making a little up top.
Schrick 268's: The best all around cams for these motors. There are considerable gains between these cams, and the Autotechs. Powerband gets a bit nicer as well, making power above 6k
. There are several brands that replicate these fairly closely. Then, there are other branded 268's which have different specifications, particularly when it comes to lift(how far the valve is being pushed open). Schrick lift is .4488". DRC has the best and closest match with their 268's at .450" lift.
276's-298's: There are a number of larger duration hydraulic cams available. These cams idle pretty rough, and make power to the low 7k rpm range. They're usually best if paired up with an aftermarket intake manifold, and engine management beyond chip tuning to get them running right. Many of these size cams will not work with a mk4 headgasket, as their duration makes piston contact.
8. Headgasket/Headbolts
Headgasket- The oem mk3 head gasket is paper. It gets the job done, however there’s an easy, cheap upgrade here. The mk4 12v vr6 is the exact same engine internally, and uses a thinner, metal head gasket. This raises the vr6’s stock compression of 10:1, to 10.5:1. This is worth 5-7whp on a stock motor.
Headbolts- The oem ones will suit just about any N/A application. Just remember that these are stretch bolts, and ONE TIME USE. ARP makes headstuds for these motors, which are nice if you’re planning on pulling the cylinder head on a regular basis as they are reusable.
9. Exhaust Manifolds/Downpipe
You've probably read it a million times, headers don't work on vr's. There's got to be a way to make power with them, i don't doubt that, but nobody's had great success with them. So, this brings me into grinding up stock parts...
Exhaust Manifolds: These are just hell inside. They're super restrictive, usually nowhere near gasket or exhaust port size, and can be made to flow much much better. It's a dirty job, and i use grinding stownes or carbide bits on my straight die grinder to port them. It takes quite awhile, but i believe average gains on a modified engine are in the 7-10whp range when paired with a modified downpipe.
Downpipe: The inlets are tiny! They've also got a big weld on the inside of the inlet flanges! AHH! Solution, have the flanges welded from the outside, and grind out the inner weld. I also usually grind a good bit out of the flange itself....one part i do gasket match.
If you do these things, get fresh gaskets. They're cheap, and exhaust leaks are no fun, or good for solid o2 sensor readings.
Paul made a diy on this: http://forums.vwvortex.com/zerothread?id=3603731
10. Exhaust
I feel that if you have a stock car with some bolt-on's, you can’t beat the Tectonics 2.5” with a borla. The price is reasonable, the quality is solid, and they make good power.

Once cams or headwork are added, I suggest a 3" exhaust system. I gained 7whp and 5ft/lb going from a 2.5" system to a 3".(specifics shown in the link below) Mandrel Bending solutions produces the only bolt on 3" exhaust system for our cars. Nice, quality stuff here.

2.5" vs. 3" dyno thread

Testpipe-This replaces the stock catalytic converter. Honestly, our stock cat isn't horrible for what it is. 42draft designs makes a great piece. Evan is the man http://****************.com/smile/emthup.gif
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· Registered
13,626 Posts
Discussion Starter · #2 · (Edited)
Re: How to build a relatively inexpensive, reliable, powerful Vr6. (root beer)

Timing chains! These will go bad anywhere from 80-200k. Sooner if maintenance hasn't been up to par. The only thing i've got to make clear here is how to properly intall the upper hydraulic chain tensioner. This looks like a 27mm bolt on the back of the upper timing cover.

1. Submerge tensioner in oil, i like to use a clear cup.
2. Pump it a couple times to get the air out.
3. Once your cam gears are on, put your upper timing cover, and install the tensioner.
4. Turn your motor over a bunch of times by hand, and triple check timing before reinstalling your intake and starting. This builds some oil pressure up, and lets your chains get jiving in the right direction.

Timing is always the last thing i do before starting an engine. If you time it, and let it sit, it can very easily hop a tooth on one cam overnight.

11. Engine Block
“The Miracle Stock Block”
The majority of the best power on N/A Vr6’s has been made on stock blocks. They’re very stout, and take a ****load of abuse. Stock, they have Forged Crank and Rods, and Cast pistons. None of this limits power to the point that anything on top of the motor does. Most don’t mess with it whereas the norm in other car communities. This is normally a very costly part of building a motor. One reason stock blocks make good power is that oem vw bearings were of high quality. They hold up well, and at a higher mileage, their wear simulates a ’loose’ motor. Oftentimes, when race motors are built, clearances(rod/bearig/crank, and main/bearing/crank) are kept larger, or ’looser’ than what might be used on a street motor in an effort to help everything rotate easier and with less restriction.
Cliffs: If your rings are holding compression, leave your block alone
Pistons-A bigger, higher compression piston will always make more power. Forged piston sets for these motors are usually 7-800 dollar range before the required machine work. Stock bore is 81mm, and 83.5mm can be had using a stock head gasket, bringing it out to a meaty 3.0l. Oem cast 2.9l vw pistons are also available at 82mm. In terms of compression, there haven’t been many high compression vr builds to my knowledge. Higher compression makes more power, however I believe that there are valve clearance issues to be considered when beginning to bump compression beyond 11 or 11.5:1 depending on the exact design of the piston, and how much the block and head have been decked. This avenue is fairly unexplored.
Stock 81mm piston vs. Wiseco 83mm

Rod bolts-If a VR6 ‘blows up’, it most likely spun a rod bearing. This is mainly due to oem rod bolts being a little cheesy. They are stretch bolts, and simply wear out over thousands of miles. The best option here is to install arp rod bolts into a stock motor. There is info out there advising to clearance the rod caps for these bolts but I have experience running these bolts in stock motors/rods with no work done. Simply remove 1 bolt at a time, replacing with the arp hardware and torquing to ARP’s specifications(very important). I have seen stock blocks with arp rod bolts hold up for a long period of time on VRT’s in the 500hp range. There's one doing 150 in the 1/4 mile and making 700+ horsepower.
12. Flywheel/Pullies
This is the first thing bolted to the engine’s crankshaft between the engine and the transmission, and is what the clutch bolts to. The lighter it is, the more power it should make in theory. Having experience with the range of weights, I currently run the Autotech 7lb piece. For my purposes, it is best. However, for a daily, I’d stick to the 10-13 lb flywheels as they offer a little more feel, and ‘umph’ when starting off or shifting. Many have claimed that light flywheels cause clutch chatter, but I have never had this experience. I believe this is a sign of junk components.
Flywheel bolts
Oem works fine for the most part. The Stock bolts are stretch bolts, and SHOULD be replaced every time the flywheel is replaced. If you really want to get busy with it, Arp flywheel bolts for a mustang work. A VR6 needs 10. 10mmx1.00. http://www.summitracing.com/parts/ARP-254-2901
Lighter is better. How much performance is it worth? I don’t know. Less stuff spinning, more efficient. If it’s a issue of whether or not it’s worth the money, the crank pulley is the most effective as the stock one is very heavy. The stock pulley offers some harmonic dampening, but not enough jump up and down about a lightweight crank pulley. There are some performance harmonic dampeners out there being developed for the VW market, but even if these to become available for VR6‘s, I wouldn’t worry about it except on a turbo car.
13. Clutch
For most purposes, especially on a n/a street car, the stock sach’s clutch is great. When getting into shifting hard, or when a lot of wheel hop is present, the first thing to break are the straps and rivets on the stock pressure plate.
If an upgrade is necessary, at one time i would have recommended Clutchnet. However, recently it seems as though the company has lost a key player. Quality and customer service have suffered.

People are all over the place when it comes to what clutches are reliable. I know of some running Bully clutches. I'm currently having great luck with a Competition clutch Stg3 with a kevlar segmented disk. Others are having luck with various stages of Clutchmasters. The big thing you're looking for is upgraded straps and rivets in the pressure plate. Also, for a street car, don't get a pucked disk.....look for something full face or segmented, and with a sprung hub. Do not buy a solid hub disk.

Just don't get a SPEC. SPEC is garbage for our cars for whatever reason. They do great things for other makes from what i hear, but they routinely fly apart within a few hundred miles.

Clutch safety switch bypass Your clutch saftey switch is located behind your dash support, at the top of the clutch pedal. This is a 2 pin plug that plugs in toward the firewall. Unplug your clutch safey switch, and jam a regular old fuse in the plug to jumper the two sides together. This allows you to start the car without pressing the clutch down.(early cars start without the clutch in anyway) If you upgrade your clutch to an aftermarket pressure plate, you should not be starting your car with the clutch depressed. With this much spring pressure, it is very stressful on your engine's thrust bearings, particularly when the car isn't running. Thrust bearings keep the crank centered in the engine, front to back. So this can lead to problems in the bottom of the motor....crank walk. So, you're going to have to remember to knock it out of gear from now on.

Upgrade clutch forkWith a stiffer pressure plate, many have bent their clutch forks. This is the piece that the slave cylinder pushes to release the pressure plate. Flipside customs makes a nice reinforced clutch fork that’s hard to beat in terms of price and quality. http://www.flipsidecustoms.com
Pressure plate bolts: I like to replace these every 2nd or 3rd time i put a clutch in a car. I torque them to 20ft/lbs, and use blue loctite. These tend to back out, so do this right.
14. Cooling System
Precautionary: Thermostat/Fan switch
Except in particularly cold climates, on any vr6 that is modified, I recommend at least a low temperature thermostat and/or a low temperature fan switch(in the radiator). These are hot running motors, and they run well like that. However, when timing is advanced or when compression is raised, they can ‘ping’ or detonate when hot. These are cheap, and function as maintenance items anyway.
Coolant-Many swear by and only use g12 for coolant. I see no problem with that. Personally, it’s easier for me to obtain regular old dexcool, so I run that. I haven’t seen any issues running it in my 7 years of vr6 ownership, and in large amounts of side work. Even if it has whatever properties in it that cause whatever properties in vw aluminum to wear over time, it’s not enough to get all fired up about.
Water pump-The stock one is plastic impeller, and it’s FINE. Vr’s can have the same problem that 2liters have here with the plastic impeller, but it's more often tied to some old funky coolant. If you really want a metal one, that’s cool too.
Crack pipe- This is the coolant pipe that goes across the front of the motor, from the water pump housing to the thermostat housing, with a nipple in the center for the oil cooler/heat exchanger. Waste money on a billet one if you really want to. But if you can follow, if your stock plastic one survived 1xx,xxx miles with your previous owner putting garbage coolant in it, why spend $80 instead of $8?

15. Ignition System
Spark Plugs- NGK BKR5E.(Or the bosch equivalent Bosch FR8LDC) Dual or single electrode, they both work well. These are the best plugs for these motors imo. They’re some of the cheapest as well. If you forget the part number, go into the parts store and say, “Hi, I need 6 of the cheapest copper NGK plugs for a 97 Jetta VR6, please”. Even if you have a gti, just say Jetta, and even if you have a 98, just say 97. I've come to understand parts guys.
Plug wires- oem bosch. I like the mk4 wires because of the pull tabs they have.
Coilpack- The oem coil pack is great. The general opinion of them is bad as overtime the plastic deteriorates, and cracks, allowing water to get into them. This happens with all vehicles with coil packs, ours cracking isn’t unusual. It’s just one of those things that you’ve got to buy sometimes.
Many people have been running MSD coil setups. I feel that this is pretty unnecessary. I had an msd setup that I bought off a buddy who was parting his f.i. setup and ran it on my old motor. I would say that the car ran a little smoother, but I don’t feel that it added any power. All that, for a hit on reliability. The external wires are going to come off at some point, and leave you on 4 cylinders. Many are having no problems on high hp vrt’s in the 500hp range with stock coil packs.
16. Lubrication
Oil-Everybody uses everything. It doesn’t really matter. Synthetic is basically….synthetic. I run 5w30 Amsoil. Just don’t run 20w50, that’s stupid.
Filter-I use oem from Germanautoparts. At least you know they’re of good quality, and it’s actually cheaper than the purulators or whatever you can get at the local parts stores.
Oil pump-I’ve seen very few fail. If you’re having pressure issues, replace it. The biggest thing is to keep the pickup screen from becoming clogged. Parts of timing chain guides tend to come off, and get stuck up in there.
17. Engine Management
The VW market is the only one I have ever seen to be so behind on technology. Other makes almost all go to some form of standalone ecu, or chipped/tunable stock ecu as a preliminary modification. Talk to a Honda guy who knows what he’s doing sometime….you’ll get “You’ve NEVER tuned your car?”. We don't HAVE to, because our mass airflow sensors, as much of a crutch as they can be, allow our ecus to compensate for anything but extreme variances. This lack of tuning has been a long trend as there has never been a large VW performance aftermarket. There are no chipable tuning programs available to us.(such as Hondata)
There are many ECU’s available to us, however most require a wiring harness to be built, which is a daunting task for many. Lugtronic, I think is one of the best options here. Kevin makes plug and play harnesses for the majority of VW harnesses.
Paul made a post after installing Megasquirt:
Which brings me to…..chips.
They all work, but I’ve found GIAC to make the best power. I’ve run a GIAC non-cam chip on everything from a bone stock motor, to a bolt-on motor, to a 3liter 11:1 compression motor. It has run all of those fairly well, and reliably.

Tectonics tuning also makes good chips.

C2's chips are cool because they remove the ecu's need for a second o2 sensor, and secondary air injection. However, i have heard that they do not allow misfire codes to be stored. I don't like them....too many issues across the board.
18. Fuel
Run 93.
Your stock fuel pump will work for everything but extreme cases.
Your stock injectors(19#), will work for everything but extreme cases
Fuel injector cleaner- The absolute best 'dump in' cleaner is B&G 44k. It is a little pricey at $20 a can, but is the only product that i've seen make a difference. If you really want to get serious, there are some companies such as witchhunter.com that flow, balance, and rebuild injectors. However, aftermarket 19# injectors are so cheap that it might be worth getting those if you're having fueling problems.
19. Transmission/drivetrain
This is a weakspot in a vr6 car, but a few small changes make a big difference.
Ring and Pinion: There are multipe ring and pinion options that can be taken from various o2a's to change up the car's gearing. A higher ratio ring and pinion makes for shorter gears. This is the same as changing the rear end gears in a muscle car. The ring is bolted to the differential. It changes the final drive of the transmission. 3.39 and 3.65 are both fairly mild. 3.94 is starting to get a little aggressive, whereas, 4.24 is really short. I'm talkin, start in 2nd short.

3.39-all mk3 vr6's,
3.65-Corrado vr6's and some 4cyl o2a's
3.94-Some 4cyl o2a's
4.24-mk4 2liter o2j's and others

Shorter 3rd gear We have a LOOOOOONG 3rd(1.308) in all mk3 vr6 transmissions. If you go to http://www.vwtransaxles.com/code.html, you can find the ratios for all vw transmissions that are important here. This long 3rd makes the 2-3 shift fall a bit further out of powerband than what is best, and makes the 3-4 too far into the powerband. If you swap your 3rd for a 1.345-1.47, i think you'll like it. If you'd like to play with gearing options, check out Team mfactory calculator loaded with vr ratios

Differential: Internally, the weakpoint in an o2a is the stock differential. A differential allows for one wheel to move faster than the other and still have sufficient power given to it. When you go around a corner, the outside wheel moves faster, and your differential is working. The problem with using factory differentials and performance driving is that when one wheel starts spinning, it continues to spin. This applies for straight line traction as well as pulling out of turns and unloading the inside wheel. This also happens to be the part that usually flies out the back of the transmission when it blows up.. Popular LSD, or Limited slip differntial replacements such as Quaife, Peloquin, and Autotech are expensive, but will last you forever. When one wheel begins to spin with these differentials, the other wheel continues to get power, limiting spinning. Not necessary, but a must for exceptionally hard driving.
Transmission fluid: 75w90 GL-4 fluids must be used. Best all around, cheap, easy to obtain, is Pennzoil syncromesh. I usually drain this through the 17mm Allen bolt on the rear, bottom of the transmission's differential housing. I fill through the vehicle speed sensor hole at the rear of the top of the transmission. This requires a transmission funnel. The transmission is full when fluid runs out of the 'fill hole' on the front of the transmission, another 17mm allen.
Axles: I like Empi axles, and Mobil 1 grease.
Alternative shifter options: The best short shifter for the o2a was the dieselgeek piece. The rest of the shifters on the market are pretty lame imo. Nothing's really wrong with stock. I really like those verdict motorsport bushings.
Mk4 o2j shifter swap: By swapping the shifterbox, cables, and shift tower(in the transmission) from a mk4 5spd car, shifts will be much smoother and precise. Putting the Mk4 shifter box in only requires that a few holes be drilled in the floor, and some extended studs bolted into the box. This is a great shifter, and oem upgrade, and i'm suprised more people don't try it!
Motormounts: You should run upgraded ones. At least bfi .5 inserts. They don't vibrate at all. Stock mounts allow for too much engine/transmission movement, which is a big cause of drivetrain issues. It also makes the car much nicer to drive and shift.
Transmission brace: Corrado's and early passats came with an extra brace on their transmission, between the back of the case, and the rear trans mount. This should be run on anything that's getting driven aggressively. A thread i made awhile back: http://forums.vwvortex.com/zerothread?id=3981073

This is a part of your friendly mk3 drag racer invasion

Modified by root beer at 3:53 PM 2-15-2010

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5,166 Posts
Re: How to build a relatively inexpensive, reliable, powerful Vr6. (root beer)

just curious as to why you think running 20w50 synthetic is a bad thing? especially if the car is tracked?
Also include some tricks to lower intake temperatures. Phenolic spacers, heat shielding under the intake manifold, and relocating the IAT into the intake pipe using an Mk4 1.8T sensor.
And there is 1 header proven to make power. S2 metalworks. Theres a thread on it here http://forums.vwvortex.com/zerothread?id=4458534
But as always the cost of it can be offsetting especially since you can make the stock stuff flow pretty well with some work
Good write up considering there are a million threads a year asking whats the best way to make power out of a VR in N/A form

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Re: How to build a relatively inexpensive, reliable, powerful Vr6. (root beer)

Quote, originally posted by root beer »

Coilpack- The oem coil pack is great. The general opinion of them is bad as overtime the plastic deteriorates, and cracks, allowing water to get into them. This happens with all vehicles with coil packs, ours cracking isn’t unusual. It’s just one of those things that you’ve got to buy sometimes.
Many people have been running MSD coil setups. I feel that this is pretty unnecessary. I had an msd setup that I bought off a buddy who was parting his f.i. setup and ran it on my old motor. I would say that the car ran a little smoother, but I don’t feel that it added any power. All that, for a hit on reliability. The external wires are going to come off at some point, and leave you on 4 cylinders. I know of lots of people having no problems on high hp vrt’s with stock coil packs.

I ended up with this MSD when I bought Tim's motor and the MSD finally crapped out after about a year of me driving with it. In running a coilpack, I notice no tangible difference between the two. Yes, the MSD looks really, really cool...but if you ain't worried about looking pretty, spend your money elsewhere.

Oh, and that Corrado trans brace may be the single-most easy, cheap insurance you can give your car if you like romping on it.

Modified by son of planrforrobert at 9:21 AM 2-13-2010

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Discussion Starter · #6 ·
Re: How to build a relatively inexpensive, reliable, powerful Vr6. (WannabeVWguy)

Quote, originally posted by WannabeVWguy »
just curious as to why you think running 20w50 synthetic is a bad thing? especially if the car is tracked?
Also include some tricks to lower intake temperatures. Phenolic spacers, heat shielding under the intake manifold, and relocating the IAT into the intake pipe using an Mk4 1.8T sensor.
And there is 1 header proven to make power. S2 metalworks. Theres a thread on it here http://forums.vwvortex.com/zerothread?id=4458534
But as always the cost of it can be offsetting especially since you can make the stock stuff flow pretty well with some work
Good write up considering there are a million threads a year asking whats the best way to make power out of a VR in N/A form

This oil pump simply isn't geared for something as heavy as 20w50. Nor are the lifters designed for it, more imporantly. Talk to road racers, they run light oil....oftentimes straight weight.
I was actually thinking about adding the 1.8t sensor stuff. I'll put something in there on that. I'm not big on phenolic spacers, i'll put something in there about it, but they're just pretty expensive for the gains you get.
That s2 metalworks header has only been proven by s2 metalworks. I haven't known of anyone who's opinion i trust running it successfully, so i don't consider it to be proven.
Thanks for the input! http://****************.com/smile/emthup.gif http://****************.com/smile/emthup.gif

Modified by root beer at 9:21 AM 2-13-2010

Modified by root beer at 9:24 AM 2-13-2010

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3,480 Posts
Re: How to build a relatively inexpensive, reliable, powerful Vr6. (son of planrforrobert)

Quote, originally posted by son of planrforrobert »

I ended up with this MSD when I bought Tim's motor and the MSD finally crapped out after about a year of me driving with it. In running a coilpack, I notice no tangible difference between the two. Yes, the MSD looks really, really cool...but if you ain't worried about looking pretty, spend your money elsewhere.
I went with MSD. I can say that the car definitely runs a bit smoother, but I did it for a different reason. I figured in the long run it will be cheaper. If one of the coilpacks goes bad I 'll only be spending $42 instead of having to buy an entire coilpack. Even if all three went bad all at once it would still be less expensive than the cost of a new "oem" coilpack.

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3,067 Posts
Re: (pop&lock)

when putting my mk4 vr6 together i opted for a paper head gasket.. ya.. i was being cheap and I needed it then and there..
my jetta is SO slow.. it just doesnt make sense.. ive never really looked into it as i didnt really care... but im getting annoyed lately. I think it has alot to do with the HG. Im gonna try and do some of the stuff you mentioned..
As for a gutted or cloned 2.9 mani.. that **** works.. i swap a mani on my old mk2 on the dyno. The car made 7whp and 12wtq on the motor and 15whp and 35wtq on spray.. the biggest difference was the powerband on the street... i revved that car down to the clock.. so much fun.

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34,572 Posts

Quote, originally posted by root beer »
Thanks guys. Figured i should put it in one spot before i start forgetting things

You got plenty of time to get old and forget
You know it's bad when you start doing the same things over 5-10 years later and then go "oh ****, THAT's why I did what I did"

You got PM with my comments. http://****************.com/smile/emthup.gif

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15,657 Posts

GREAT write up!! I really enjoyed reading it.
My opinion: I found the MSD setup to be a very nice upgrade. Might have just been a mental thing, but I felt that it gave the motor a little more pep and it revved a bit faster.
Also, the short shift options, I have had the B&M short shift kit in my car since 2005 and have loved it since it went in. I also took about an inch off of the shifter shaft. I also have the Verdict Motorsports aluminum bushings in as well. I love how all of these things work together.

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2,988 Posts
Re: (root beer)

Good write up. http://****************.com/smile/emthup.gif
I have followed your's and paul's threads for some time now and commend you both for your knowledge and willingness to answer questions in the 12v community.
I do have a question regarding the porting in the head. You stated that you are not gasket matched and wonder why?
I understand the 12v head has a few issues to overcome and am interested in the best way to do this. I did start on one over the summer knowing that I still had a back up if needed. That being said, I needed it because I went too far.
I was wondering if you could elaborate on the key points you focused on? As well as how close you did get to gasket matching the intake and exhaust ports? Also, did you polish the exhaust ports?
Sorry for all the questions.

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Discussion Starter · #14 ·
Re: (92jetta9a)

Hah, we were actually discussing this. I could go into what all i worked on, but i don't actually have flow data, just track times that i like to think are partially a result of what i did there. Try to read up on headflow a little before you start, and take your time.

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Re: (top fuel)

Awesome write up, with some of the names in here you know the thread is good

As an aside, I have a set of Cat 268's in my car, a good friend of mine did the installation, he's a very trusted source of knowledge for me and upon his suggestion I went W/O valve springs with the cams. His theory was the stiffer springs are likely to impede the drivetrain a little bit and it was unlikely I was going to get valve float unless I was REALLY hammering it. I've been running them like this for 6 months and have zero complaints. A good friend with an R32 is running Schricks in the same manor. http://****************.com/smile/emthup.gif

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Re: :)skribble:)

this definitely needs to be sticky'd to the top of the mk3 forums.
i read this completely, and agree with everything, only exception i would make is about the billet "crack pipe"; the oem plastic ones break the stupid bottom nipple with ease, and the $80 billet one may be expensive, but ive wasted nearly $80 on gas, time off at job, and overall aggrevation breaking a plastic one at 6:30 on a sunday evening.
that, and to add about short shifters, the RSD unit from tmtuning is nearly identical to the dieselgeek, and can be purchased brand new still

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Re: How to build a relatively inexpensive, reliable, powerful Vr6. (root beer)

Good Read! It's great having reputable 12v knowledge on the forums. Your's and Pauls opinions/pointers are some of the few i truly value http://****************.com/smile/emthup.gif

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Re: How to build a relatively inexpensive, reliable, powerful Vr6. (Andras.R)

Regarding the MSD coilpack setup.... I had a intermittant misfire that wouldn't go away.. changed out coilpacks, plugs, wires, nothing made a bit of difference.
Installed the MSD coilpacks, and the MSD wires and viola, misfire was gone.
I remember reading somewhere that the stock coilpack is ~ 10kv, where as the MSD is ~ 40kv. I run mine with a ford ballast resistor @ 9v or so as to not fry the coils with full juice.
If yours works, then great stick with it, but this is another option.
Regardless, the cost of a stock coilpack + wires far exceedes the cost of the MSD setup.
I'd have to say the single biggest thing thats transformed my car is a LSD + 3.94 R+P - It REALLY wakes the car up.
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