Although I'm strongly considering the Greedspeed/Neuspeed 250hp (K04) upgrade. I can't help but wonder whether it would be worth it to go to 300 or 350 hp. We all know that TAP and AMS/ABT offer such upgrades. I hoped that someone here has done such an upgrade, at what cost, their impressions, etc.<p>Thanks<p>Rob B.<br>A4 1.8TQM Silver, Neuspeed chip, Neuspeed race springs, Neuspeed front & rear sways, Bilstein front & rear shocks, RamAir filter, Ronal R28's, Pirelli 225/45, clear corners and side markers. Future mods: Cat-back exhaust, K04 turbo, AvantGarde "S" body kit, surface to air missiles, etc.

Start thinking about your choices in terms of practicality, not horsepower. The modern automobile, much like the modern highway and the modern personal computer, is really more of a system engineering problem than an internal combustion puzzle. You need to start examining your choices, and start examining systems that will be stressed and/or overloaded by your upgrade choices. For example, beyond 235 horsepower, the binding mechanicals inside the Tiptronic torque converter begin to bind at designs more than 10% outside design parameters. Transmissions are, in general, overengineered, but not infinitely so. The manual can go up to 260 hp. That's HP and not BHP. When you think of transmissions, the relevant numerical values appear at the plate and the interlock, not at the wheels. Next is your exhaust and failsafe valving and throughput. Engine breathing, especially in the 1.8T, is extremely important and directly linked to usable hp output (and, to a lesser degree, linked to torque reaching the road). The failsafe valving both before and after drivetrain interchanges (the gearbox is the only drivetrain interchange that is hp/torque limited in the A4, it seems) will ensure that your engine, transmission, and driveline are not overpowered or quickly asked to absorb positive or negative load through the system. In the 1.8T sequential (or, in one setup I saw recently, bi-route serial) valving seems the system of choice. It's cheap to set up, never fails, and saves your engine in overspin and overrev conditiosn. Overspin is not as large a problem with the K03 and K04 as it seems to be with larger turbos, which may not spool down in time to match engine output. Spool-up is never a major concern, but because of the peaky engine output of larger turbochargers during a negative change in speed of turbo mechanicals, this could become a problem if you went to more extreme turbo units. The next problem is braking. I, like many people on this board, believe that the order of performance ranking is this:<p>1) 5 to 100 to 0<br>2) Quarter mile<br>99) 0 to 60<p>What is your braking concept? The A8 brake kit seems the most reasonable, possibly with the Brembo discs if needed. Remember, faster-cooling brakes warp more quickly if not used in succession and given warm and cool stages. Brake ducting may or may not be a good idea. Is this a track dedicated car or a street car also?<p>Getting back to the most important part of this from a driving point of view: where do you plan to go with the transmission? The six-speed from the S4 is a good choice, and the ratios are well chosen for that power range. Above 300hp the 1.8T has a narrower power band, so you'll need six gears to keep it in a balanced range. Worse comes to worse, one can swap Porsche gearsets into Audi transmissions for almost any combination of ratios imaginable.<p>Good luck with your upgrades, and I hope this helps.<p>Cameron

300 hp A4? The TAP pricing of stages approximately doubles every stage for about a 20-40 hp step. I would like to have a lot more power than stock but can't imagine putting 300 hp to reasonable use unless you are racing the car. <p>Go buy stocks, go on a 2 month vacation or do something reasonable with the money you would spend on going beyond 250 hp.<p>Sorry, I know it is not my business, just MHO.

Great writeup, Cameron. Just thought I would add something else, and that is the effect of higher boost on effective compression ratio. I have seen some general rules of thumb on this, but can't remember them (every 3 psi boost increases compression ratio 1 point, or something like that - anybody seen something similar?). I tend to think that boosting much beyond stock can result in effective compression ratio exceeding a value that can be comfortably accommodated with gasoline available on the street (have always seen large line of Turbo cars at gas pumps at Mid-Ohio race track trying to get the 105 octane racing fuel - at about $5 a gallon, as I remember - during the race track driver's education events I have participated in). I don't really know if the knock sensor and cumputer electronics can totally counteract this.<br>

I looked in to the 290HP kit. Not available yet and no one can even quote a price. We found one in England (the price), from pounds to dollars, about $14,000.00! installed! Best guesstimates for the US is around $8000.00 to $9000.00. I have the 250 kit, but I would wait for the biturbo for that much money.

I have done the TAP Stage 7 upgrade so maybe I could give you a little bit of advice. If you search the archives, you'll see the big debate that went on back in April regarding issues such as fitment problems that I experienced, burnt valves, etc. This time around, I'll give you MY OWN opinion in terms of reliability and performance. Let me start by saying that I've returned my cylinder head (valve, valve seats) back to original Audi specs instead of TAP's stage 7 specs. Since then, the engine itself has been trouble free. Performance wise, there is a substantial difference for every 2-3 psi of boost you increase/decrease. Usually, I set the wastegate at around 15-16 pounds max for everyday driving. This is the same setting I use on the track and I've done two full-day, all-out, track sessions in the past month. The current problem I'm experiencing has to do with the Turbonetics wastegate. My unit keeps coming loose therefore causing the boost to be unstable. If it becomes very loose, I will be left with around 10 psi only. This isn't such a big problem, as I plan to replace the unit with a different one.<p>Lastly, I'm sure everyone would like to know the performance though I haven't got aorund to measure 1/4 mile times with the G-Tech. Here are some comparisons, which may give you guys some ideas:<p>'97 M3 3.2<br>- supercharged by ERT (5 psi max boost)<br>- 3.46 differential<br>- Sachs sport clutch, Turner lightened flywheel<br>- Hamann Euro M3 exhaust<br>- dynoed at 282 hp at wheels (around 330-340 flywheel)<p>From a standing start, the A4 (12psi 1st gear, 14 psi 2nd, 18 psi boost in 3rd 4th and 5th gears) has a slight advantage (the clutch definitely can't hold the power to get a decent launch) and around the 1/4 mile mark, the M3 is pulling ahead by around 1 and a half car lengths. <p>96 Mercedes C36<br>- stock<p>At the end of 4th gear, the A4 is ahead by 1 and a half car lengths.<p>92 Eagle Talon<br>- TDO5- 16G (stg 3)<br>- large side mount intercooler<br>- ACT stg 3 clutch<br>- HKS VPC, EVC<p>No comparison here. If we are both running 17 psi, the Talon gets ahead by around 2-3 car lengths around the 1/4 mile.<p>If you would like more info, you can E-mail me direct or post a reply.<p>Sincerely,<p>Jon

Some questions about the TAP 7 kit..<p>1) What turbo did they use.. T04E/Stage III turbine, what A/R ratio is the turbine housing?<p>2) Are you running CAT's in the car?<p>3) Injector size (how many cc/min are u running?)<p>4) Did you address the compression ratio issue?<p>5) Race gas? or Street gas.. <p>Well it seems that the biggest problem about getting high boost into the A4 is the compression ratio.. I bet if you run race gas the car would run alot stronger... Almost seems like you need 2 chips.. 1 daily driver (low - mid boost) 2 high boost program (race gas).. Getting new pistons for the car is really easy I would image just send a factory one to J&E and bingo.. for a few hundred dollars you get forged low compression pistons.. Next thing todo is get a custom head gasket made... drop the static compression down to around 8.5 - 8.9 .. You may loose some bottom end.. but what you gain in boost will more than make up for it.. hehehe It will be hard to beat the Mitsubishi cars because they are running around 8.9:1 or 8.5:1 compression and at 17 psi they motor is not pulling back timing like mad to fight detonation.. If you were to take a Fluke scope meter and watch the detonation sensor output while making a pass you will see that at 9.5 and 17 psi WE are pushing it for a turbo car.. It just shows that the 1.8T is a excellent motor! to run 17 psi on a car with 9.5:1 compression..AMAZING!!!! image if you drop the compression down to 8.9 and goto 19-22 psi!!!!<p>

Wow! Impressive response. I will thank you even more once I get an interpreter. Just kidding. At the very least, your response has made me realize that much more needs to be taken into consideration if I intend to go beyond those 250hp kits offered by Greedspeed/Neuspeed and Wett.<p>Nothwithstanding, I would imagine that those aftermarket tuners (i.e., TAP and ABT) that offer 300+ hp kits have taken into consideration what you have stated in your reply.<p>Thanks again.

I wish I could tell you what the A/R ratio of the turbine housing is but I'm not too sure about the specs myself.. The turbo looks like a K24, not the hybrid RS2 unit but I might consider using a K26 when I do upgrade the bottom end. (pistons, rods, etc hopefully when someone besides ABTcomes out with a 2.0 conversion) The injectors are uprated Bosch units and I could find out what the cc/min rating is if you are interested. In connection with this, I'm actually concerned with whether the fuel pump is up to the task. Does anyone know if the stock fuel pump is sufficient?<br>In terms of the cat, it is a sport cat from TAP. By the way, it there is any detonation, I can't seem to detect any. Neither can I feel any retardation of timing... Under full throttle conditions, my Halmeter AF30 shows that the engine is running at the extreme side of rich, constantly. In passing, it may be worthwhile noting that I have an ABT front mount intercooler plumbed into the system along with the stock unit, which may in some ways decrease the chances of detonation.<p>Sincerely,<p>Jon

Slap a external fuel pressure guage on the car and make a pass at full boost watch the pressure as you reach redline.. Take your static fuel pressure reading (remove the vacum line going to the fuel presssure regulator and then add 1psi fuel pressure for each psi of boost.. thus if you are at 40 psi then at 17 your car should hold a steady 57+ psi.. if you see it drop then below the 1 to 1 mark then you know fuel pump is starving out on the big end.. BUT if you are running pretty rich already then maybe you are ok.. Hmm have you tried to monitor timing while making a pass? Hmm interesting run some street gas 93 octance or so and then make a pass with some race gas (unleaded of course around 108 octane sunoco (here in Houston)).. See what your timing curve does... It would be a good experiment .. oh also hook up a EGT guage another good indicator of what is going on.... Hmm.. I have not looked at the Air flow meter for the A4 yet.. any flow ratings? oh well man only if I can win the lottery and stay home and tune my A4 all day long .. hehehehe..

I have a 250HP Kit and I can tell you I believe more mods are needed thank any tuner is currently offering.<br>Heat is a problem in the A4, I challange any one that can produce a constant 250HP for more than 2 minutes!<br>Insufficiant Intercooler air flow to keep it cool, Air Box ducts heats up as insufficient<br>sheilding and close positioning to "HOT" turbo and poor air flow across turbo.<br>If these where not the case 250HP would be ample for most people.<br>I bet many people who have gone to 300HP kits are only getting 230-250HP reliably anyway becaust of the above mentioned proplems.

Stocks? Where do you think I got the money to pay for this? Thanks to the technology stocks experiencing a meteoric rise after having bought in at or near 52 week lows, I have some "extra" money to have fun with.<p>Vacation? No time ... oh well.<p>Thanks for the advice though.