Does anyone regret getting their K04?

[Grouch]

I have the itch for more power and been reading up on every K04 thread I could find. Although 99% of people seem to love theirs, I'm curious if anyone regrets or wishes they just stuck it out stage 2 and save the few thousand bucks?

[A4 Centaur]

Not sure how many folks will be unhappy, but I can say with out a doubt, I am extremely pleased with my JHM K04-R. Would do it all over again. Understanding the folks who got the "genuine" Borg Warner are making a few more HP, the K03 should never have been specd with a 3800 Lb. car

[ps2cho]

Not sure how many folks will be unhappy, but I can say with out a doubt, I am extremely pleased with my JHM K04-R. Would do it all over again. Understanding the folks who got the "genuine" Borg Warner are making a few more HP, the K03 should never have been specd with a 3800 Lb. car

I don’t think that’s a fair comment - for fuel economics and the average driver, the KO3 performs more than adequate. Putting a KO4 simply bastardizes the S and RS models.
Makes no sense in my head at all to use it.

[Chatchie]

A stage 2 A4/allroad is a fast car. This era of cars making 500+ hp off the showroom floor makes us a bit jaded. I think we are in the golden age of cars right now. Back in 2000 you'd have to spend quite a bit on a car to dip into the 13's. Now we can do it with just an ECU tune and no hardparts.

The tuned K03 makes about the same torque as a K04 but Im looking for some more fun up top. I think 2-3k is a bargain for the performance gains and driving experience.

[djo7]

The jump between ko3 and ko4 wasn’t enough jump for me. Had I known I the slight power gain I got I would have just saved the money and stuck with the ko3 on stg2. I needed the car to run and there was a ko4 for sale in my town. It was a reasonable swap but not a huge jump.


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[whats77inaname]

Nope.

[Grouch]

The jump between ko3 and ko4 wasn’t enough jump for me. Had I known I the slight power gain I got I would have just saved the money and stuck with the ko3 on stg2. I needed the car to run and there was a ko4 for sale in my town. It was a reasonable swap but not a huge jump.


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That is what conflicting me right now. Dropping 3000 on minimal gains. Esp considering E85 is out of the question for me and only have 91oct in my area.

[A4x]

The jump between ko3 and ko4 wasn’t enough jump for me. Had I known I the slight power gain I got I would have just saved the money and stuck with the ko3 on stg2. I needed the car to run and there was a ko4 for sale in my town. It was a reasonable swap but not a huge jump.

This. Also K04 gets you more turbo lag which kind of offsets the gains you get up top. Sure, it is crazy fun to wind out this little engine with K04 power, but I would have a hard time saying it is worth $3000. Depends on many factors like your financial situation, your DIY skill level, you future car plans for the next 3-5 years, etc.

I know the mod bug can bite hard and make you long for the K04 power. I would say it is 50/50 if it is worth it or not. Most people who have taken the plunge will be too biased to tell you it is not worth it.

The best advice I can give is to find a local K04 car that can take you for a ride, or better yet, let you drive it and feel it out.

K03 is a lot of fun with the torque down low. Don't underestimate that. But it sure leaves you wanting above 4000 rpm. K04 is a lot of fun above 4000 rpm, but it leaves something to be desired with low-end torque.

[Nano909]

A stage 2 A4/allroad is a fast car. This era of cars making 500+ hp off the showroom floor makes us a bit jaded. I think we are in the golden age of cars right now. Back in 2000 you'd have to spend quite a bit on a car to dip into the 13's. Now we can do it with just an ECU tune and no hardparts.

The tuned K03 makes about the same torque as a K04 but Im looking for some more fun up top. I think 2-3k is a bargain for the performance gains and driving experience.

I wouldn't say a stage 2 B8 is a fast car, not at all. Too heavy of a car for the power it makes. Can it get off the line quickly? Sure, but then it quickly falls flat. That's where the K04 comes in.

If you want to have more fun on the freeway with other cars, then the K04 is ideal. The K03 simply lacks top end. I on the other hand do not mind sacrificing some torque for some horsepower.

[A4 Centaur]

I don’t think that’s a fair comment - for fuel economics and the average driver, the KO3 performs more than adequate. Putting a KO4 simply bastardizes the S and RS models.
Makes no sense in my head at all to use it.

This isn't an opinion response, and it's a fair response.

The K04 is the same size externally, and many of us here on this forum have beat this point home a billion times. The K03 is not as powerful and certainly not as reliable as the K04 from Borg Warner or even the Hybrid crowd.

I didn't speak of "adequacy" the OP's question was to a "regret" which I answered no. Again, I wasn't talking about an average driver either.

The K04 is a better piece of kit and certainly for an A4 doesn't "Bastardize" an S4 in any way.

Many on this forum have been working on "improving" the B8 since it came out, again thousands of threads about updating, upgrading and improving upon what many feel is an under performing engine in a 3800 Lb car. You are entitled to your opinion. The facts are the K04 builds better power and makes much more power, and stage 2 is LAME compared to a tuned K04.

The K04 will possum stomp a K03. Period

[Perry01]

The facts are the K04 builds better power and makes much more power, and stage 2 is LAME compared to a tuned K04.

+1

[bb-tt]

This is like the third thread on this subject, and nothing has changed. There are a couple people who regret it most of us are very happy with the upgrade. My own experience was after switching from the TT to the Avant I was disappointed as it was almost anemic in comparison. After installing the k04 the car puts smiles on my face. The fact remains if you want a really fast car don't buy a b8, if you like the b8 and want to have more fun and have the money then the k04 is a great upgrade.

[seanvines1]

The facts are the K04 builds better power and makes much more power, and stage 2 is LAME compared to a tuned K04.

The K04 will possum stomp a K03. Period

I mean, isn’t this expected? A proper K04 setup would cost anywhere from $3.5k-5k and a stage two setup would be around $1200. When you’re spending 3 times the amount i’d sure hope you’d possom stomp them. When it comes down to it, a tuned K04 does not make an A4 a “fast” car. Quick sure but not fast by anymeans.


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[Grouch]

Thanks for the replies. I'm more or less set on getting it sometime in the future. Just basically trying to justify the cost of it.

[bb-tt]

Thanks for the replies. I'm more or less set on getting it sometime in the future. Just basically trying to justify the cost of it.

Buy the k04 when it is on sale, and if you have ie tune upgrade cost is minimal think it was 150. IIRC I was just under 3k for k04 hfc and tune.

[Perry01]

I mean, isn’t this expected? A proper K04 setup would cost anywhere from $3.5k-5k

I purchased my CTS K04 for around $2k and installed it in my garage. The software upgrade from Stage 2 was $50.

[cuda2000]

What is quarter mile time stage 2 k03 vs k04? Thats all I need to know to determine if its worth it.

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[Chatchie]

I purchased my CTS K04 for around $2k and installed it in my garage. The software upgrade from Stage 2 was $50.

Who did your TCU tune? I definitely want it but it seems HPtuners is the only way.

[Shane Horning]

What is quarter mile time stage 2 k03 vs k04? Thats all I need to know to determine if its worth it.

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Apr on 93 fuel will run around 13.2 @ 102. That's what mine runs

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[Shane Horning]

Stage 2 that is

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[A4x]

What is quarter mile time stage 2 k03 vs k04? Thats all I need to know to determine if its worth it.

https://www.audizine.com/forum/showt...1-4-mile-times

In general:
stage 2: low to mid 13s
K04: mid 12s

0-60 times between the 2 should be similar, maybe a few tenths better on K04. The increased turbo lag on K04 offsets the gains you get above 4000 rpm in a 0-60 mph run.

[bb-tt]

Buy the k04 when it is on sale, and if you have ie tune upgrade cost is minimal think it was 150. IIRC I was just under 3k for k04 hfc and tune.

Apparently my memory is crap just looked it up, paid just over 2k with tax and then 50 for the tune upgrade.

[BMWManiac]

I thought my 2013 Audi A4 was horribly slow. The Stage 2 setup is a huge improvement. If/when my KO3 fails, I'll upgrade, but I don't think I need to go that route just yet....cost to hp ratio just isn't there to me

[Perry01]

https://www.audizine.com/forum/showt...1-4-mile-times

0-60 times between the 2 should be similar, maybe a few tenths better on K04. The increased turbo lag on K04 offsets the gains you get above 4000 rpm in a 0-60 mph run.

Turbo lag is something you may experience during everyday driving but can be offset by changing your driving style. On a WOT 0-60 run, there is ZERO turbo lag when launching using AMAX. I even get wheel spin on all 4 tires. I rev my motor to 3600 RPM and launch without a trace of lag and reach 60 MPH in 4.2 seconds. This is over a second quicker than Stage 2 which is a huge difference.

Who did your TCU tune? I definitely want it but it seems HPtuners is the only way.

I tuned it myself with HP Tuners software.

[Stazi]

I’m just sitting here....waiting.... for IE to put their stuff on Black Friday sale so I can join the K04 club. Already have all the other mods on the car; full exhaust and HFC, intake, ECS IC.....etc.

Bought my K04 and upgraded the CHRA with a $200 Melett unit, so new turbo set me back <$900 and it’s the same exact thing the big boys are flogging for $1200-1500.

[Chatchie]

APR just launched a sale. Saving me $400 on the K04 + intercooler combo. Not bad. My shop is a an APR dealer and they do a K04 flat rate install for $300. How can you beat that.....

[Perry01]

If you are going to upgrade to a K04, it’s best to get the real thing. This is what IE has to say about it,

“Majority of non genuine k04 or hybrids make less power and are not properly adjusted on the wastegate. Seen around 50+ customers try and do it. I’d definitely recommend getting a genuine K04 for the B8/8.5 platform.”

[EvolutionArmory]

People who are disappointed by K04 numbers probably don’t realize that peak power is kind of meaningless next to how long it makes that power for in the power band.

If 2 turbos make 300 peak wheel torque but one holds it for 2K longer, what turbo would you want?

The only thing I’m disappointed with about my K04 is that I bought a hybrid JHM and not a CTS Turbo K04.

[EvolutionArmory]

If you are going to upgrade to a K04, it’s best to get the real thing. This is what IE has to say about it,

“Majority of non genuine k04 or hybrids make less power and are not properly adjusted on the wastegate. Seen around 50+ customers try and do it. I’d definitely recommend getting a genuine K04 for the B8/8.5 platform.”

This is so true. I have the only JHM K04R car in the B7 section that actually runs right and all the CTS K04 cars are faster. So this statement also applies to B7’s as well as B8’s.

[Chatchie]

Also this whole argument that the K03 makes the same torque as a K04 is silly. It makes the same torque for a very short amount of time compared to the bigger turbo.

Look at the area under the line, it's not even close. The spool time isn't that far off either. Aaaaand the K04 makes more power longer. Why is this even an argument?



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[Grouch]

I thought my 2013 Audi A4 was horribly slow. The Stage 2 setup is a huge improvement. If/when my KO3 fails, I'll upgrade, but I don't think I need to go that route just yet....cost to hp ratio just isn't there to me

This is basically my dilemma. Here in LA, I only have 91oct option and can't run E85 because manual transmission. The cost to hp ratio for that small of a HP increase makes me very hesitant to get it. If I want to add a water/meth kit to run 100oct, that will set me back another 800+.

[EvolutionArmory]

Also this whole argument that the K03 makes the same torque as a K04 is silly. It makes the same torque for a very short amount of time compared to the bigger turbo.

Look at the area under the line, it's not even close. The spool time isn't that far off either. Aaaaand the K04 makes more power longer. Why is this even an argument?



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Because like I said, people see a peak number and don’t look at the powerband as a whole. Thanks for the graphs to drive it home.

Some of them probably think that a K03 making 22 PSI is faster than a K04 making 20. They just don’t realize that the K04 is still making 20PSI at 6K when the K03 is making 12 🤣

Peak PSI and peak HP and TQ numbers don’t say a lot about anything. Its just a tiny section of the powerband.

[A4x]

Here's the APR charts overlayed. You lose power below 4000 rpm. It gets even worse with 91 octane.

[Stazi]

If you are going to upgrade to a K04, it’s best to get the real thing. This is what IE has to say about it,

“Majority of non genuine k04 or hybrids make less power and are not properly adjusted on the wastegate. Seen around 50+ customers try and do it. I’d definitely recommend getting a genuine K04 for the B8/8.5 platform.”

I’m not the first to run this combo, so I’m not too worried. I know how to adjust the wastegate, if required. This isn’t my first rodeo with turbo charging, just my first Audi. What I thought was surprising was that when I asked IE what crack pressure they tune for, they said they didn’t know. How can you not know?

I will set it for 5psi crack pressure and adjusted upward if required.

What crack pressure is everyone else running?

[Perry01]

Here's the APR charts overlayed. You lose power below 4000 rpm. It gets even worse with 91 octane.

Above 3800 RPM, the graph shows that the K04 produces much more power than it gives up below 3800 RPM.

Who drives below 3800 RPM anyway 😏

[EvolutionArmory]

Here's the APR charts overlayed. You lose power below 4000 rpm. It gets even worse with 91 octane.

but from 4K to redline you’re making way more power.

And look at how much longer you’re actually making torque. Who cares if you’re making more earlier just to start losing it right away. The K04 torque band is way flatter.

If you tried to argue that K04’s aren’t worth it by using that graph overlay, I think it backfired on you honestly.

[EvolutionArmory]

I’m not the first to run this combo, so I’m not too worried. I know how to adjust the wastegate, if required. This isn’t my first rodeo with turbo charging, just my first Audi. What I thought was surprising was that when I asked IE what crack pressure they tune for, they said they didn’t know. How can you not know?

I will set it for 5psi crack pressure and adjusted upward if required.

What crack pressure is everyone else running?

JHM sets theirs to 10 PSI so that’s where I’m at now. They sent out a shit load of turbos that were set to 6 and mine was one of them. Made adjustment and did logs and my boost is dialed in now.

[Stazi]

JHM sets theirs to 10 PSI so that’s where I’m at now. They sent out a shit load of turbos that were set to 6 and mine was one of them. Made adjustment and did logs and my boost is dialed in now.

Thanks for that info!!


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[EvolutionArmory]

Be careful with that eBay turbo. What is the wastegate spring rated for? You kinda need that info.

[Stazi]

Be careful with that eBay turbo. What is the wastegate spring rated for? You kinda need that info.

EA, the most important part of the turbo has been replaced with a known high quality Melett CHRA with EXACT specs of a K04-0064.

The exhaust/compressor housings look IDENTICAL to what JHM, USP and ECS are selling. AFAIK, only CTS took a Transverse K04 from an S3 and welded a different compressor outlet to suit the Longitudinal layout for our cars. Please correct me if I’m wrong.

Spring rates of the wastegate are questionable. That I can agree with. But do we know the actual spring rate of the CTS/BW K04 wastegate?

I’m going to try and measure it today; but even if I have that info, no one seems to know WTF the BW spring rate is, so the info is almost inconsequential.

I have not been able to find anyone post the kg/m or lb/in spring rate of another K04 wastegate spring. I assume that when they talk about aftermarket wastegates like Mambatec or Forge that the “5lb spring” in those case is 5lb/in...or is it 5psi for crack pressure? I would think the former.

That’s the problem with people abbreviating units of measure, you don’t really know what you’re comparing against.

So far only info I have seen posted is crack pressure. Some varying answers here. I have seen 5psi, and now the latest info says it should be 10psi.

At the end of the day, I would have thought that with an ECU solenoid (N75) controlling boost pressure (through controlled bleeding), it will adjust duty cycle of the N75 to get what it needs unless the required duty cycle is outside of the envelope due to too high a spring rate in the wastegate (which will cause over boost spikes), or the wastegate spring rate is too low and you run out of duty cycle for bleeding off boost signal to the wastegate (can’t reach max requested boost).

ETA: from responses posted on the forum, the eBay wastegate seems to work fine with the IE tune, so long as the crack pressure is set right.

ETA2: Found this post were APR says 6psi on K04 cracking pressure: https://forums.vwvortex.com/showthre...System-Coating


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