400 HP not possible? Project car thread, need advice

[twentyeggs]

Hey people. I am new to Audi and forced induction in general. I’ve always been into modding cars as a hobby.
The list of vehicles I’ve owned in order are as follows:

Daily drivers: 1994 Acura Legend (sold), modded 1996 Nissan Maxima (totaled), 1987 Jeep (destroyed on purpose doing a dukes of hazard type jump off a dirt mound/jump), complete bolt on 2006 Nissan Maxima (still own), modded 2006 G35 (still own)

Toys: 2007 Kawasaki ZX-6R (sold), 2006 Yamaha R1 (sold), 2008 Honda CBR 600-RR (sold)

Project cars: 480HP 1996 Corvette race car (blew up, caught on fire after shop failed to secure the fuel return line), 2009 Audi A4 (new project car).

So I have been in contact with some performance shops and right now I am talking to GMG racing in California. My goal is to get around 400AWHP/TQ. Money is not a factor. The audi I want to mod is a B8 A4 2.0t Quattro. However, I am finding it very difficult to get any straight answers. Looking at APR’s stage two numbers they claim they can get 70 HP and 90TQ out of their tube/downpipes ect.. I live in the Nazi state of California where you can’t smog cars unless you know someone or swap it all back to stock for inspection. So I got this email from one of APR’s dealers.

“Thanks Andrew, but 400 HP at the wheels (528 HP crank) is not do-able on a 2.0T. A stage 3 upgrade with K04 turbo, FMIC, down pipe, injectors, tune, exhaust system, intake, fuel pump, etc., is going to be right at about 290HP at the wheels. I can give you a quote for this if you like? You would be looking at about $2600.00 in labor to install these components, which is $5200.00 every time you need to smog it to remove everything, smog the car, then re-install.”

So forgive my ignorance, but that doesn’t seem right to me. APR claims they can get more than 290 with just a tune. I am used to v6 v8 cars. My corvette was making almost 500hp N/A. I thought forced induction cars were much easier to make power out of. I am very knowledgeable about American muscle, I built my motor from top to bottom with the best of what is out there. And there are hundreds of options and ways to go about building an LT1. But the A4 seems to be like pulling teeth in terms of getting a respectable amount of power out of its little engine. I just want something close to my corvette. I can be happy with 0-60 time under 5 seconds, quarter mile in mid 12’s. As far as suspension goes, I’ve got a handle on that.

Just wondering what your guy’s thought are on this email reply and if you have any suggestions on what I can do to get to my goal.

[hyperunion]

Ko4 setups are around 12.5 quarters.... Upcoming efr kit has yet to be determined hp or tq numbers.. But recorded a 12.1 in quarter with a Manual transmission... An efr equipped car with a zfhp8 speed could potentially break into the 11s.....

[o1turbo30v]

The problem will simply be the stock fueling, there is no good/doable way to increase the volume of fuel in these engines. If you look at APR's stage 3 EFR World Record turbo thread, Arin does a really good job explaining the limitations of the stock fueling and how the ecu controls it. To me, trying to get 400hp out of this engine with "money being no object" is a fruitless en devour, you would be way better of selling the a4 and getting a S4 (since $ is no object) with the massively better 3.0 supercharged engine, those engines make over 400hp with just a chip and pulley upgrade. Big turbo A4's never work out well $ wise.

[lettuce]

lol. "Spend $13,000 buying and installing everything we sell for your car and you'll max it out at 290hp."

Gotta love APR.

[van462]

Big HP numbers often come at the expense of low end toque numbers. You could have a custom exhaust manifold built to hang a huge turbo off of. Extra injectors could likely be fitted. But it would be a 4000 lbs car that wouldn't produce usable boost until around 5K RPM. So it would be this car that would be a slug until it comes on line unless you like driving in 2nd gear all day. SMOG relies on CARB approved parts so that makes it a CA track car. Give 034 motorsports a call and basically buy a time attack setup (they are selling their B5 a4 for $60000). Likely an R8 will be cheaper.

[Smellie]

Wtf? APR Stage 3 isn't even K04.

APR's Stage 3 is still in development with an EFR 6758, which i believe will make high 300's whp/wtq figures


Fueling is definitely the worst part about these cars if you wanna go for big power.


I'm currently making 329 whp/348 wtq on k04 + meth setup running APR's 100 oct tune.


Sucks that Jerry didn't dyno his EFR 6758 setup, wouldve been awesome to see the numbers

[twentyeggs]

The problem will simply be the stock fueling, there is no good/doable way to increase the volume of fuel in these engines. If you look at APR's stage 3 EFR World Record turbo thread, Arin does a really good job explaining the limitations of the stock fueling and how the ecu controls it. To me, trying to get 400hp out of this engine with "money being no object" is a fruitless en devour, you would be way better of selling the a4 and getting a S4 (since $ is no object) with the massively better 3.0 supercharged engine, those engines make over 400hp with just a chip and pulley upgrade. Big turbo A4's never work out well $ wise.

Interesting... considering the s4 is just 10k more than a similar a4 maybe I'll just do that before I start shelling out money... gotta think about this one. I just don't know if I can get the s4 without getting the v8. Seems like there is so much potential there with the v8. I am trying to keep the cost down, because my dream car is the Nissan GTR. I started a second savings account literally titled "GTR Savings" about a year and a half ago, but at the rate of putting in just a quarter of my monthly income, it will take another 3.5 years to buy it. I am really trying to be responsible on not financing a car because I am still paying off student loans. Financing an alpha 9 package on the other hand

I think spending around 30k is enough to keep me happy until I can afford what i really want. The reason I went with the A4 is because I like the whole sleeper thing. Pick up the a4 for 15k, throw another 10-15k on upgrades and be happy, but it looks like hitting the 400 mark is out of reach.

So If I go with the S line should I get the SC3.0 or V8. I imagine I'd be very tempted to F/I the V8.

[hyperunion]

B6 b7 v8 has almost no potential with out a 10k or more supercharger kit.... Factory supercharged v6 has quite a bit.... 12.1 to 11.5 second quarters with smaller pulley stg 2 kits ....

[Darksol80]

Interesting... considering the s4 is just 10k more than a similar a4 maybe I'll just do that before I start shelling out money... gotta think about this one. I just don't know if I can get the s4 without getting the v8. Seems like there is so much potential there with the v8. I am trying to keep the cost down, because my dream car is the Nissan GTR. I started a second savings account literally titled "GTR Savings" about a year and a half ago, but at the rate of putting in just a quarter of my monthly income, it will take another 3.5 years to buy it. I am really trying to be responsible on not financing a car because I am still paying off student loans. Financing an alpha 9 package on the other hand

I think spending around 30k is enough to keep me happy until I can afford what i really want. The reason I went with the A4 is because I like the whole sleeper thing. Pick up the a4 for 15k, throw another 10-15k on upgrades and be happy, but it looks like hitting the 400 mark is out of reach.

So If I go with the S line should I get the SC3.0 or V8. I imagine I'd be very tempted to F/I the V8.

I had a 99 WS6, I get the V-8 love. With that said, forget the older V-8 S4 or RS4. Get a B8-B8.5 S4, or get a C7 S6, mod it and call it a day. You said money was no object!

http://www.goapr.com/products/ecu_up...tfsi_s6s7.html

http://www.goapr.com/products/ecu_up...tfsi_b8s4.html

http://www.goapr.com/products/ecu_up...fsi_b85s4.html

No one notices the S-car Audi's really. They are really understated looking when the looks are left stock. BTW not trying to be a APR booster but their site was easy to nab links too. Use whatever tuning company you feel comfortable with.

[Darksol80]

. A stage 3 upgrade with K04 turbo, FMIC, down pipe, injectors, tune, exhaust system, intake, fuel pump, etc., is going to be right at about 290HP at the wheels. I can give you a quote for this if you like? You would be looking at about $2600.00 in labor to install these components, which is $5200.00 every time you need to smog it to remove everything, smog the car, then re-install.”

What is that about? Injectors and fuel pump to run the KO4? Since when? Their site doesn't mention that.

[earhythmic]

It's sad to see the B6/B7 S4 page flooded with "this broke" and "that leaks" threads when it used to be as active as this B8 forum with fresh builds and new mods. Buuuutt: http://www.audizine.com/forum/showth...old-air-intake

[B44]

Even if you do a frikkin ls7 swap with crazy hp the question always comes to the fueling system and components and tune which is very limited.

[twentyeggs]

I had a 99 WS6, I get the V-8 love. With that said, forget the older V-8 S4 or RS4. Get a B8-B8.5 S4, or get a C7 S6, mod it and call it a day. You said money was no object!

http://www.goapr.com/products/ecu_up...tfsi_s6s7.html

http://www.goapr.com/products/ecu_up...tfsi_b8s4.html

http://www.goapr.com/products/ecu_up...fsi_b85s4.html

No one notices the S-car Audi's really. They are really understated looking when the looks are left stock. BTW not trying to be a APR booster but their site was easy to nab links too. Use whatever tuning company you feel comfortable with.

Yeah, there is definitely a lot to fall in love with in a nice throaty V8. I had a triple cone cold air intake, 510 comp cams, long tube headers, and straight pipes in my vette that made it sound beastly. When I was in school I lived in an apartment complex. While it was always music to my ears (most of the time preferred listening to the car than the radio) I am sure my neighbors hated me. I sometimes parked outside the complex when I had to leave at 5am for 6 o'clock clinicals. Especially with a light weight flywheel and stage 3 clutch I had to give it a little blip on cold starts to get going. once it warmed up i could release the clutch without any gas to get going.

Hey your sig mentions you have the professional series BCA muffler Bearings... sweet mod! I was thinking about getting some muffler bearings to compliment my high flow canooter valve, but I need to get a set of metric screw drivers for the instal first so it is done right.

[RW12]

Gotta say, why not just sell the Maxima, G35, A4 and at least one bike then get a GTR. Seems like pissing away money to me, especially with student loans...that is, assuming you actually own those vehicles...

[twentyeggs]

Gotta say, why not just sell the Maxima, G35, A4 and at least one bike then get a GTR. Seems like pissing away money to me, especially with student loans...that is, assuming you actually own those vehicles...

woops i forgot to add that i sold the all the bikes. I sold my Kawi 6 years ago, and the other two last year. ill go edit that. I am without a bike at the moment and with the vette gone, hence my itch for speed...The G35 is technically mine but my wife drives it, it's her car now lol. She had a truck that kept breaking down so I told her to get rid of it take over the insurance and use the G. So I just have the Maxima and Audi. I had a friend fall on hard times and bought his Altima with the intent to sell it back to him when he had the money again, but he ended up getting a new job and financing a newer altima. So I fixed up the problems in the Altima and sold it for almost a $1,000 profit, sold the R1 and CBR and put it all in the GTR savings.

[RW12]

woops i forgot to add that i sold the all the bikes. I sold my Kawi 6 years ago, and the other two last year. ill go edit that. I am without a bike at the moment The G35 is technically mine but my wife drives it, it's her car now lol. She had a truck that kept breaking down so I told her to get rid of it take over the insurance and use the G. So I just have the Maxima and Audi. I had a friend fall on hard times and bought his Altima with the intent to sell it back to him when he had the money again, but he ended up getting a new job and financing a newer altima. So I fixed up the problems in the Altima and sold it for almost a $1,000 profit, sold the R1 and CBR and put it all in the GTR savings.

uh huh - well good luck with the modding

[Slick_B8]

If youre really serious, i would suggest you give integrated engineering a call. They seem to know more about what theyre doing then anyone else out there. Its laughable that people think it isnt possible to achieve that much power but none of them have even looked deep into it because they rather, and i qoute, 'just trade in your a4 for a s4'. Lmao gtfo id rather sport a 4 banger that makes more power than a v6 with a few bolt ons. And if anyone really wants to discuss how much it will take to make a 4 banger even compete with v6, im open for a discussion, not an argument.

[twentyeggs]

If youre really serious, i would suggest you give integrated engineering a call. They seem to know more about what theyre doing then anyone else out there. Its laughable that people think it isnt possible to achieve that much power but none of them have even looked deep into it because they rather, and i qoute, 'just trade in your a4 for a s4'. Lmao gtfo id rather sport a 4 banger that makes more power than a v6 with a few bolt ons. And if anyone really wants to discuss how much it will take to make a 4 banger even compete with v6, im open for a discussion, not an argument.

Well I mean I am all for making sleepers out of cars. My Maxima runs circles around the G35, and head to head will outrun an srt8 charger, wrx sti, and similar cars. my corvette was just a little c4 that everyone though they could outrun, but surprise surprise I would outrun new mustangs, porche 911's, many modified cars like 350-370z's civics (you would be surprised how fast they can be with 30psi on slicks) Challengers c5 zo6's ect.. the drag strip was my weekend home lol I haven't been since the vette died.

So yeah I am serious about it. But it's gotta be within reason. I mean, people build twin turbo AWD fox body mustangs but that doesn't mean its worth the investment. If it takes 20 grand for an a4 to compete with an s4 that only needs a pully and a tune what's the point? what do you know that I don't? From what I've seen and heard now, the limiting factor is the fuel delivery. I hear people talking about upgraded fuel pumps but are they not enough? Can't tuners modify the ecu to ignore the fuel cutoff or whatever it does to limit fuel?

[Slick_B8]

The way i see it, think about how much your saving buying a a4 vs an s4. Its a 10-15k difference usually. Not sayying thats always correct. Now that you have 8-10k that you saved from buying an s4, an engine rebuild with forged internals is gonna run you about 4-5k, that usually includes rods, pistons, springs etc And labor. Now with the remaining 5k or even less, you can get your own aftermarket turbo and push it till theres no tomorrow aswell and fuel delivery parts. My only understanding is how difficult finding a good custom tuner. But if you search deep, theres always people out there with the capacity of doing so. And yea, if you find the right tuner, im almost 100% sure that he can work with the fuel delivery. I believe anything is possible, whether you have an open amount of money or a budget, all it takes is just taking your time and doing your homework on the topic.

[xpoweruk]

The other thing to consider is the S4 will always be worth more come sale time

[Project Quattro]

So yeah I am serious about it. But it's gotta be within reason. I mean, people build twin turbo AWD fox body mustangs but that doesn't mean its worth the investment. If it takes 20 grand for an a4 to compete with an s4 that only needs a pully and a tune what's the point? what do you know that I don't? From what I've seen and heard now, the limiting factor is the fuel delivery. I hear people talking about upgraded fuel pumps but are they not enough? Can't tuners modify the ecu to ignore the fuel cutoff or whatever it does to limit fuel?

I think the issue with fueling is the injectors, which APR alluded to in the (lengthy) stage 3 thread. I think their 290hp figure in the email was a typo, because the K04 exceeds that and the stage 3 kit should be in the upper 3s. Another thing to factor in is that the A4 weighs 500lb less than the S4, so you need a higher power output from the S4 to achieve similar results. I would say that you could buy and build an A4 which performs as well as a stage 2 S4 for less than you'd spend to buy and tune the S4. The only hiccup is that you're in Cali, so you might need to do some workarounds or tweaks to make the car smog-compliant. If they don't do a visual inspection, or if a high flow cat will pass a visual inspection, it should be possible to get the car to pass at stage 2. If they require all factory parts or do a sniffer then I have no idea how that would go.


Sent from the Pedal Responce boardroom

[twentyeggs]

I think the issue with fueling is the injectors, which APR alluded to in the (lengthy) stage 3 thread. I think their 290hp figure in the email was a typo, because the K04 exceeds that and the stage 3 kit should be in the upper 3s. Another thing to factor in is that the A4 weighs 500lb less than the S4, so you need a higher power output from the S4 to achieve similar results. I would say that you could buy and build an A4 which performs as well as a stage 2 S4 for less than you'd spend to buy and tune the S4. The only hiccup is that you're in Cali, so you might need to do some workarounds or tweaks to make the car smog-compliant. If they don't do a visual inspection, or if a high flow cat will pass a visual inspection, it should be possible to get the car to pass at stage 2. If they require all factory parts or do a sniffer then I have no idea how that would go.


Sent from the Pedal Responce boardroom

Well so far I have been able to find a smog shop to pass my cars in this ridiculous nazi state. But if worse case scenario occurs i'd just swap my stock parts back on for the test. Its a price to pay but for me its worth it.

Is the s4 really 500lbs heavier? what about the s4 adds that much weight? That's crazy. Edmunds says the difference is 320lbs but again the engine itself can't make up that much extra weight so I wonder what else it is. I wonder if the exhaust system or rims are heavier. I was able to drop 280 lbs in my maxima, by switching rims and doing exhaust work among a few other things... made a significant difference. Because the maxima has 290HP stock and FWD it purposely comes with heavy 55lbs rims to reduce torque steer (with a full size spare). So going to 16lbs rims, getting rid of the spare, replacing the heavy piping from the y-pipe to the muffler eliminating the HUGE 40 lbs resonator and 2nd un-metered cat did some serious weight reduction.

[twentyeggs]

Something to consider when comparing the A4 and S4 is reliability. In order to get an A4 to the power of a Stage 2 S4 requires significant modification vs simply tuning and adding a pulley. It's been my experience the more you mess with on an engine, the more can go wrong. So would a complete engine build, big turbo A4 be as reliable as an S4 with a tune and larger pulley? When my vette blew its engine, snapping pushrods and popping off rocker arms, it was all down hill from there even though I did a complete bottom and top end rebuild. I was a bad experience until it finally caught on fire.

Check this out.. how many of you have seen snapped in half push rods? lol


Those were the ones I could get out, another two were snapped in half and stuck in the right side valley. I had to remove the heads to get to them.

[Project Quattro]

Well so far I have been able to find a smog shop to pass my cars in this ridiculous nazi state. But if worse case scenario occurs i'd just swap my stock parts back on for the test. Its a price to pay but for me its worth it.

Is the s4 really 500lbs heavier? what about the s4 adds that much weight? That's crazy. Edmunds says the difference is 320lbs but again the engine itself can't make up that much extra weight so I wonder what else it is. I wonder if the exhaust system or rims are heavier. I was able to drop 280 lbs in my maxima, by switching rims and doing exhaust work among a few other things... made a significant difference. Because the maxima has 290HP stock and FWD it purposely comes with heavy 55lbs rims to reduce torque steer (with a full size spare). So going to 16lbs rims, getting rid of the spare, replacing the heavy piping from the y-pipe to the muffler eliminating the HUGE 40 lbs resonator and 2nd un-metered cat did some serious weight reduction.

It depends on what trims and configurations you're comparing but the difference can be in the ballpark of 500 lb. the S4 has the bigger motor, dual exhaust, different suspension, and I think the DSG is heavier than the A4s manual or automatic trans.


Sent from the Pedal Responce boardroom

[A4 Centaur]

The EFR kit will be around 400 CHP?

[Allowencer]

As someone stated here, the limitation is fueling. Since the Audi 2.0T motor is a direct injected motor, the fuel delivery is a whole different animal.

OP, your LS* series motor - its fuel is port injected; meaning the fuel is sprayed into the intake port and 'swirled' into the combustion chamber on the intake stroke. It's not a cleanly balanced A/F mixture, but works as we all know. In general, you jam in more air, you'll need more fuel. To achieve more fuel, the computer leaves the fuel injector open longer (called IPW - injector pulse width). The issue there to monitor is the fuel rail pressure. By having the injectors stay open longer, don't forget to keep all cylinders in mind (firing order), pressure could drop. As long as the fuel pump can keep supplying volume and pressure to the rail - no issues. At some point you will max the IPW of an injector (based on firing order) and a higher flow injector will be needed. This will allow you to lower the IPW's (since more volume is releasing per pulse); however, you need to make sure the rail can supply enough volume, the fuel feed and the fuel pump. A fun cycle throughout! I think you all get the picture now.

On a direct injected motor - you do not have the luxury of just spraying fuel and allowing the intake to swirl it in. The fuel injector fires during the compression stroke as the piston is coming 'up' but before ignition (spark) occurs. Since that is the case, you have a VERY limited time to inject the proper amount of fuel. Not only to that point, you have to exceed the pressure that is being created within the combustion chamber during the compression stroke; otherwise, the fuel will not actually spray but maybe dribble out. This is where the High Pressure Fuel Pump comes in. Its job is to compress the fuel mixture within the rail so that when the computer commands the injector to open (which is a MUCH smaller IPW), the few milliseconds of window that is available to spray fuel, the necessary amount of fuel is supplied. There is also a standard fuel pump that is in the tank; that pump supplies the fuel to the HPFP. That is something that could easily be upgraded; however, that's only 1 part of this equation.

When you add more air - you need more fuel right? At some point you will crest the capability of what the HPFP can provide because it can, physically, only provide 'x' amount of fuel within the 'y' amount of time under 'z' amount of pressure. Going to a larger injector only increases your capability window by a mere marginal gain since the root of the issue is at the HPFP.

Now you might be saying - "well can't someone make a new, bigger HPFP?" Sure... but it isn't cheap! ARP has stated it would take like +10k to do this... I have no comment on that since I've never really investigated what that route could theoretically cost to R&D. However, what I can provide is how the HPFP works. There is a "follower" that rides on an extra lobe on the exhaust cam (4 sided lobe). This follower operates a spring and piston like diaphragm. Each lobe's side represents each cylinder and the apex of each lobe is where the fuel is compressed, supplied to the rail so then it can be injected into the combustion chamber. If anyone understands fluid dynamics; how can you achieve a higher pressure ceiling with a liquid (gasoline!) and maintain stability under peak RPM load along with higher cylinder pressures (remember, more air in the form of boost, will dynamically increase cylinder pressures).

Hope that explanation helps everyone understand.

[bluetori]

I love and very much enjoy reading about all these threads that people want more out of there A4 and a lot of people tend to tell them to buy an S4, and it does seem more enjoyable to take a car that's not as fast as say a Toyota FWD. I think that eventually this 2.0 will be a beast with such continued interest. I sadly will be probably leaving my car basically stock as I am more interested in modding the old 20v instead, and my motorbikes.

[shaunm82]

Well so far I have been able to find a smog shop to pass my cars in this ridiculous nazi state. But if worse case scenario occurs i'd just swap my stock parts back on for the test. Its a price to pay but for me its worth it.

I may have to PM you on this one~

[b6onboost]

IMO, upgrading a 2.0T to 500chp (~400awhp) is outside of reason. This isn't specific to the A4, but even more mod friendly and tuner supported cars like an Evo or STI require major modification to reach that power level. Built motor, big turbo upgrade, fueling, tuning, intercooling, exhaust, ect. You're left with a car that isn't that reliable and a powerband that isn't that useful outside of a drag strip. If you want a race car there are plenty of better options. A 4cly luxury sedan simply isn't one of them.

So yeah I am serious about it. But it's gotta be within reason.

[twentyeggs]

Yes, I also really like the whole making a slower car fast. If I did go the S4 route, I'm sure a lot of people would face palm but I'd seriously consider debadging it. When your first car is a sleeper, and you grow up owning nothing but cars people underestimate, the joy that follows when they look over at you like keven hart as you pull on past them can't be explained.

As far as bikes though, I never got into modding them. I mean, i'll throw a KNN filter, power commander, couple extra teeth in the rear sprocket -1 in front, and exhaust but really... that is all you can do unless you wanna start shelling out more than you paid for the bike. I had a buddy with a turbo Hayabusa the long swingarm ect.. I took it down the track a few times and it was more than I could handle. It's impossible to go full throttle until you're in 4th gear and even still the front wheel feels like its floating. It got me into the 200mph club in the standing mile.

[twentyeggs]

As someone stated here, the limitation is fueling. Since the Audi 2.0T motor is a direct injected motor, the fuel delivery is a whole different animal.

OP, your LS* series motor - its fuel is port injected; meaning the fuel is sprayed into the intake port and 'swirled' into the combustion chamber on the intake stroke. It's not a cleanly balanced A/F mixture, but works as we all know. In general, you jam in more air, you'll need more fuel. To achieve more fuel, the computer leaves the fuel injector open longer (called IPW - injector pulse width). The issue there to monitor is the fuel rail pressure. By having the injectors stay open longer, don't forget to keep all cylinders in mind (firing order), pressure could drop. As long as the fuel pump can keep supplying volume and pressure to the rail - no issues. At some point you will max the IPW of an injector (based on firing order) and a higher flow injector will be needed. This will allow you to lower the IPW's (since more volume is releasing per pulse); however, you need to make sure the rail can supply enough volume, the fuel feed and the fuel pump. A fun cycle throughout! I think you all get the picture now.

On a direct injected motor - you do not have the luxury of just spraying fuel and allowing the intake to swirl it in. The fuel injector fires during the compression stroke as the piston is coming 'up' but before ignition (spark) occurs. Since that is the case, you have a VERY limited time to inject the proper amount of fuel. Not only to that point, you have to exceed the pressure that is being created within the combustion chamber during the compression stroke; otherwise, the fuel will not actually spray but maybe dribble out. This is where the High Pressure Fuel Pump comes in. Its job is to compress the fuel mixture within the rail so that when the computer commands the injector to open (which is a MUCH smaller IPW), the few milliseconds of window that is available to spray fuel, the necessary amount of fuel is supplied. There is also a standard fuel pump that is in the tank; that pump supplies the fuel to the HPFP. That is something that could easily be upgraded; however, that's only 1 part of this equation.

When you add more air - you need more fuel right? At some point you will crest the capability of what the HPFP can provide because it can, physically, only provide 'x' amount of fuel within the 'y' amount of time under 'z' amount of pressure. Going to a larger injector only increases your capability window by a mere marginal gain since the root of the issue is at the HPFP.

Now you might be saying - "well can't someone make a new, bigger HPFP?" Sure... but it isn't cheap! ARP has stated it would take like +10k to do this... I have no comment on that since I've never really investigated what that route could theoretically cost to R&D. However, what I can provide is how the HPFP works. There is a "follower" that rides on an extra lobe on the exhaust cam (4 sided lobe). This follower operates a spring and piston like diaphragm. Each lobe's side represents each cylinder and the apex of each lobe is where the fuel is compressed, supplied to the rail so then it can be injected into the combustion chamber. If anyone understands fluid dynamics; how can you achieve a higher pressure ceiling with a liquid (gasoline!) and maintain stability under peak RPM load along with higher cylinder pressures (remember, more air in the form of boost, will dynamically increase cylinder pressures).

Hope that explanation helps everyone understand.

Nice writeup. Thanks for explaining this.

[b6onboost]

There's much easier and cost effective ways to get a sleepers. Most people just see an Audi sedan and have no idea the significance between an A4/S4. If you de-badged a tuned S4 and left it visually stock, you'd still get the 'WTF look' when you destroy people who think their lightly modded Mustangs, Camaros, STIs, etc are fast. Heck if you threw a set of dorky A4 17in wheels on you'd confuse a bunch of euro enthusiasts too.

Yes, I also really like the whole making a slower car fast. If I did go the S4 route, I'm sure a lot of people would face palm but I'd seriously consider debadging it. When your first car is a sleeper, and you grow up owning nothing but cars people underestimate, the joy that follows when they look over at you like keven hart as you pull on past them can't be explained.

[Frinkferta]

Get a 2.0T A3 Quattro, throw on APR's ERF kit. There is a 500HP car for much cheaper.

[A4 Centaur]

Yea, what would be nice is something like VW built for the A4 Tdi: http://www.myturbodiesel.com/wiki/vw...-1996-present/

Is there nozzle upgrade the Loba Kit comes with? Or larger nozzles for the APR kit which are 980cc very similar? The Gen3 E888 would be the platform.

The idea of nozzles, and pumps, rail etc for the Gen 3 E888 engine is $1400 from APR for this platform.

We can probably look to the Germans for a solution first potentially. If not why not get a TDI?

You could just get a TDI in say the Q7 or A7 and get busy: https://www.youtube.com/watch?v=Jxw1aOsJfOQ

Broos Engineering is claiming 421 PS and 634 Ft. Lbs. Try that out!

[Darksol80]

Yeah, there is definitely a lot to fall in love with in a nice throaty V8. I had a triple cone cold air intake, 510 comp cams, long tube headers, and straight pipes in my vette that made it sound beastly. When I was in school I lived in an apartment complex. While it was always music to my ears (most of the time preferred listening to the car than the radio) I am sure my neighbors hated me. I sometimes parked outside the complex when I had to leave at 5am for 6 o'clock clinicals. Especially with a light weight flywheel and stage 3 clutch I had to give it a little blip on cold starts to get going. once it warmed up i could release the clutch without any gas to get going.

Hey your sig mentions you have the professional series BCA muffler Bearings... sweet mod! I was thinking about getting some muffler bearings to compliment my high flow canooter valve, but I need to get a set of metric screw drivers for the instal first so it is done right.

Don't get the metric screw drivers from Harbor Freight. They are junk. Get them from Sears at least. They have a lifetime warranty.

[twentyeggs]

Get a 2.0T A3 Quattro, throw on APR's ERF kit. There is a 500HP car for much cheaper.

why doesn't APR do this with the a4? The only turn off with the a3 is the aesthetics and size. I like mid size cars and the A3 is more of a compact. Plus the B8/8.5 is such a nice looking car compared to the A3.

[twentyeggs]

There's much easier and cost effective ways to get a sleepers. Most people just see an Audi sedan and have no idea the significance between an A4/S4. If you de-badged a tuned S4 and left it visually stock, you'd still get the 'WTF look' when you destroy people who think their lightly modded Mustangs, Camaros, STIs, etc are fast. Heck if you threw a set of dorky A4 17in wheels on you'd confuse a bunch of euro enthusiasts too.

This is beginning to be an attractive idea. I wonder what the difference in insurance is between the two cars.

[twentyeggs]

So I am noticing that you can't get an S4 convertible with the 3.0t? Why is that? The only ones I am seeing have the V8...

Also the only thing about the 3.0t that I am having a hard time getting over is for so long I've wanted to get a car with turbo and slap on a big loud blow off valve. Call me boy racer but I am in love with the sound of blow off valves. But the supercharger only offers pulley whine. I've heard mustangs with loud bypass valve whooshes, but I think that is unique to prochargers, whipple ect.. superchargers. Is there any options out there to get the whooshing sound out of the 3.0t that I have not seen yet?

[Project Quattro]

So I am noticing that you can't get an S4 convertible with the 3.0t? Why is that? The only ones I am seeing have the V8...

Also the only thing about the 3.0t that I am having a hard time getting over is for so long I've wanted to get a car with turbo and slap on a big loud blow off valve. Call me boy racer but I am in love with the sound of blow off valves. But the supercharger only offers pulley whine. I've heard mustangs with loud bypass valve whooshes, but I think that is unique to prochargers, whipple ect.. superchargers. Is there any options out there to get the whooshing sound out of the 3.0t that I have not seen yet?

After 2009 they discontinued the A4/S4 convertible and released the A5/S5. Automatic only, thoigh, IIRC.


Sent from the Pedal Responce boardroom

[b6onboost]

The A4 has a different motor. The A3 has always used a GTI/Transverse motor which is different and being a VW twin there is a lot more demand for it.

why doesn't APR do this with the a4?

How can you care about insurance cost if you're saying money is no object and about to do a major build? (Starting to think TROLL)

I wonder what the difference in insurance is between the two cars.

Now really thinking TROLL. But no, you won't be able to boy-racer around with a blow off valve if you get a 3.0T

Also the only thing about the 3.0t that I am having a hard time getting over is for so long I've wanted to get a car with turbo and slap on a big loud blow off valve. Call me boy racer but I am in love with the sound of blow off valves. But the supercharger only offers pulley whine. I've heard mustangs with loud bypass valve whooshes, but I think that is unique to prochargers, whipple ect.. superchargers. Is there any options out there to get the whooshing sound out of the 3.0t that I have not seen yet?