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Many options there, your final biggest option is probably worth more than my whole car  :grin:

Up to you what path you go down, but as the HP increase the money required to get more HP exponentially increases, if you get what I mean.

If you're talking about upgrading pistons, keep in mind how much time and money that that full engine rebuild will cost too. Factory pistons are fine up to 350hp according to others on this forum.

If I do go down the route of forged piston rods, I might as well get the pistons themselves. My other mechanic pal who I collaborate with recommended that I replace my pistons if I do take the engine apart. A set of forged pistons should only set me back somewhere between 800 and 1k while I've seen rods as low as 700. But this is very far away tbh. I just want to get the car back up and running, putting down that 300-310hp.

And yeah, the more HP I want, the more I need to invest, which is why I think the K04 basic might be a good middleground. I'll get better middle and top end, more HP but will lose low down responsiveness all for under 1.2k, the price of an OEM K03. Anything more than this will turn this car into a money pit. I'd be fine with injectors and the fuel pump if I can safely push the engine to 350hp that way but I've heard a lot of mixed opinions. Some say stock rods should not be pushed beyond 330hp but I think it's the torque we need to limit. 500nm might be too much on stock rods. Maybe they can take 450?

On another note, I wonder if the S3, ED30 or other k04 engine's pistons and rods fit a BWA cause I can get a complete ED30 engine from the UK for under 1k

You don't necessarily need the S3 intercooler upgrade, but performance will suffer if you're doing more than just 1 pull from traffic lights, due to heat soak. Essentially as the heat from the extra fuel being burnt can't dissipate fast enough, the car automatically reduces power to contain the heat. E.g. the first dyno run will get you a high number, but the second much lower. Or on a race track the car will lose performance after a few turns. I wonder what @breeze thinks about this. He also has a good point about torque, you may have to start revving higher when driving after upgrading. But that's down to personal preference whether you prefer balanced torque through the whole rev range or more high end torque and less low end.

Summers we get upwards of 35c here so I'll deffo make good use of the intercooler. My general driving style keeps the engine above 2.5k at all times so I should be good. Spoke to my tuner who says he drove in both k03 and k04 tuned cars and that there isn't that much difference down low. I'd want a turbo that is balanced throughout the power range but I think that's what the K04 is. If I want instant response, I might as well get a diesel  :grin:

Downpipe costs money, but it's a good HP value upgrade after the turbo. It normally gets 15hp extra on stock cars (on high octane maps), it got me 10 extra hp on 95 octane. Not to mention my 200 cel cat really improved the exhaust note of mine even with the rest of the exhaust being stock, it sounds like a fancier raspy race car engine rather than the boring 4 cylinder that it is  :grin:. Mine is from MPDevelopments UK, €600. It does cause a check engine light which has to be coded out by your tuner though. Haven't put it through an emissions test yet, but I've kept the original downpipe just in case.

I've read that 200 cell cats wont trigger a check engine light but that's the least of my worries, we'll code it out. Passing emissions is the important part to me! I'm hoping for the same result; Improved sound, something more sporty, not your generic 4 cylinder family car but not as loud and as much drone as a full sports exhaust. Plus at 1/4th of the cost.


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Many options there, your final biggest option is probably worth more than my whole car  :grin:

Up to you what path you go down, but as the HP increase the money required to get more HP exponentially increases, if you get what I mean.

If you're talking about upgrading pistons, keep in mind how much time and money that that full engine rebuild will cost too. Factory pistons are fine up to 350hp according to others on this forum.

You don't necessarily need the S3 intercooler upgrade, but performance will suffer if you're doing more than just 1 pull from traffic lights, due to heat soak. Essentially as the heat from the extra fuel being burnt can't dissipate fast enough, the car automatically reduces power to contain the heat. E.g. the first dyno run will get you a high number, but the second much lower. Or on a race track the car will lose performance after a few turns. I wonder what @breeze thinks about this. He also has a good point about torque, you may have to start revving higher when driving after upgrading. But that's down to personal preference whether you prefer balanced torque through the whole rev range or more high end torque and less low end.

Downpipe costs money, but it's a good HP value upgrade after the turbo. It normally gets 15hp extra on stock cars (on high octane maps), it got me 10 extra hp on 95 octane. Not to mention my 200 cel cat really improved the exhaust note of mine even with the rest of the exhaust being stock, it sounds like a fancier raspy race car engine rather than the boring 4 cylinder that it is  :grin:. Mine is from MPDevelopments UK, €600. It does cause a check engine light which has to be coded out by your tuner though. Haven't put it through an emissions test yet, but I've kept the original downpipe just in case.
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What about going for stage 1 K04? Injectors and turbo with the pipework but retain intercooler and existing downpipe. To me that is quite a good value route.

So what you're saying is, ditch the downpipe in favor of the injectors? I'll have to check but brand new replacement injectors shouldn't cost that much as I have a few contacts to source them from.
Tho I feel like the downpipe might allow the turbo to breathe better and in return spool faster so I wont feel that torque loss quite that much.

On K03 vs K04… I think you will definitely notice the loss of low down torque. It is quite obvious. Not terrible but you do feel it. The K03 engines have slightly higher compression which will offset this but also limit the top end if you want big power.

From the R-Tech site:
All the factory k04 engines use a compression ratio of  9.8:1,  the AXX is 10.5:1 and the BWA 10.3:1.

Huh I heard the exact opposite. Because of the higher compression rates, these engines (BWA) will hold power better at higher rpm's. Tho I could have heard wrong cause I havent really looked into it, just saw it mentioned here or on vortex somewhere.
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What about going for stage 1 K04? Injectors and turbo with the pipework but retain intercooler and existing downpipe. To me that is quite a good value route.

On K03 vs K04… I think you will definitely notice the loss of low down torque. It is quite obvious. Not terrible but you do feel it. The K03 engines have slightly higher compression which will offset this but also limit the top end if you want big power.

From the R-Tech site:
All the factory k04 engines use a compression ratio of  9.8:1,  the AXX is 10.5:1 and the BWA 10.3:1.
5
Yeah I've used the same calculator. 215 to 225 is what I'd say it feels like. I can definitely feel that low end instant torque surge of the K03 but due to it being faulty, it dies off quite fast and proceeds to pull slightly better than a stock GTI. My money is on the wastegate actuator but we'll see when I pull it off and inspect it.

Now as far as options go, I've been thinking about them for the past few weeks and it's very hard to decide.

K03 - €1100
CHRA is most likely faulty as I and my mechanic both think there's too much oil in the intake, and the exhaust manifold appears to be cracked but could just be a streak of rust cause if that crack was real, it would already be in 2 pieces. Repairing the turbo would cost no less than 400 euros. Turbo repair/refurbish shops here only provide 1 year warranty and their reviews are evenly split between either 1* and 5*, I dont really want to take a chance. Getting a turbo from another car costs aprox 240 euros and nobody guarantees that it works, it isnt cracked internally, it isnt eating oil or that it'll last, so that's also out of the question. Getting a replacement turbo is pretty much the same deal as getting a refurbished one. Opinions are very split between mechanics but the general consensus is that you either go OEM or you go home. And they cost around 500 to 700 euros. OEM turbos cost upwards of 1k euros.

K04 - €1300
What I said about the K03 also applies here, however, I'm much more confident about a 2nd hand K04 than I am about the K03. Problem is, people know how much potential these turbos have and they are so rare that you can barely ever find them at any reseller. After searching for a week, I only found a single yard selling one for 500 euros. Now I did find brand new Borg Warner K04's for sale locally but they cost anywhere between 1200 and 1500 euros.

Downpipe - €300
Now as far as running the K04 will go, I'll be getting a downpipe with a 200 cell cat anyway to help turbo longevity since OEM I have 2 cat's and they are quite restrictive, but I wont be getting a full performance exhaust because I want my car to stay relatively quiet. Sports downpipe is imo the perfect middle ground between keeping the sound relatively stock, no drone, and providing room for power. Found an Aliexpress kit for 300 euros incl shipping which I'm fine it. At the end of the day it's just a pipe and if the cat lasts 2 years, I'm happy, given that just a sports cat is half the price of that downpipe here and they dont last any long either.

Intake - €200
Found an Aliexpress intake but dont quite like that due to the way it mounts so I'll be going with a German one, Ta-Technix, for 200 euros. It secures onto the vacuum pump so it doesnt bend in the middle like the Chinese ones do, has a heat shield and a filter. What more do I need?

DV relocation kit - €50
Aliexpress, 50 euros for the whole thing incl shipping.

Injectors - €400
With just the turbo, I can get tuned for 305-315hp. No injectors, no fuel pump, no pressure valve, or sensor. however, I will look into this when the time comes and get them all fitted. In all fairness, I don't estimate these to cost more than 400 euros, brand new (excluding the pump).

Upgraded fuel pump internals - €600
If I go down the K04 line, I'll get this. Didnt really research brands and prices cause it aint a priority right now. Between 500 and 800 euros.

Forged piston rods - €900
Arguably the second most expensive part of the whole process right after the turbo. If I'm serious enough about the K04, this will have to be done in order to safely reach 350HP. I'll probably slap in cams and pistons too.



TLDR
So in the end I really only have 3 options

K03 - €1100
Get my turbo replaced with an OEM one and know that I'll be set for life and that the car will have great low rpm torque and acceleration but will lack past 100kph and wont have any room for more power

K04 basic - €1200
Get a used OEM K04, downpipe, intake, DV relocation kit and remapped, making 310 or so HP with room for improvement. Car will probably lack low-down, wont have the same kick, but middle and top end should feel vastly different. Should be quite good when accelerating past 100 and I'll also have a much more reliable and better built turbo.

K04 all out €3000 to €4000 ontop of K04 basic
Gonna cost a lot but would max out the car. 350 to 360hp and over 500nm torque before hybridizing the turbo. Will get everything from above plus boost pipes and a twincooler setup with an S3 intercooler. Should be quite fun honestly and a pretty decent sleeper build. Not quite sure if worth it tho so I'll continue to think about my options for a while longer.

As things are right now, I'm split between K03 or K04 basic. Even if I stay K03, I'll be getting the downpipe, intake, S3 cooler and likely boost pipes too cause those were leaking. I've fixed them temporarily but I want a proper setup. So all in all my K03 plans might as well turn into a K04 job since I'll be running 70% of the required mods anyway.


This brings me to my original post and why I made this thread. K03 or K04? 03 pulls stronger down low and it's great for city driving that I do a lot but 04 provides more middle and top that comes in handy when I go on longer roads. Not quite sure about the low end but I dont think it'll be as punchy as the 03.
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Mk5 General Area / Re: What did you and your MKV do today?
« Last post by probedb on March 26, 2024, 10:01:57 pm »
Car just rolled over 216,000 miles  :grin: No plans to sell at all.

I'm at 122k and can't bring myself to sell. I look at MK7s and then just think I will miss my old girl.

Me neither, the fact it just went through it's MOT today and passed with one minor advisory for a swollen brake line and another for a screw in the middle of a tyre also makes me not want to sell. Seriously thinking maybe a Stage 1 at R Tech might be on the cards this year...at last, only taken 5 years 😅
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Mk5 General Area / Re: Wheel Color Ideas
« Last post by OllieVRS on March 26, 2024, 04:54:24 pm »
The most common colours for Monzas are black or gunmetal/anthracite, with the latter being my favourite.

I have silver Bola B1s on my black MK2 VRS, so I'd be biased to keeping your Monzas the original chrome colour  :happy2:
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EDIT: Oops I put the values in the wrong way around, but it still calculates the same hp  :grin:

I'll use https://www.omnicalculator.com/conversion/torque-to-horsepower for a conversion to metric hp.

I took the values from the first log at 5760RPM and 274Nm, as I think they're the most reliable from your log:



Horsepower can also be estimated by multiplying the MAF g/s reading by 1.25, as the engine aims to burn 1.25g of fuel for every 1.0g of air taken in, creating 1 horsepower.

So at that same RPM point it's using 172g of air, 172*1.25 = 215hp. So your real hp number (I estimate) is somewhere around 215-225hp.


Your boost is definitely too low, that the first thing to investigate. Are there any engine error codes? But if you've smoke tested and replaced the DV there's only thing left it could be.

If your planning on going K04 instead of just replacing or repairing your K03, remember you need to think about the additional costs. A K04 upgrade needs S3 injectors, HPFP upgrade (I think) and S3 intercooler. As well as supporting mods like DV relocation kit and tune.
9
Members Rides / Nimal's Shadow blue gti
« Last post by madnemo on March 26, 2024, 03:25:07 pm »
It's my 1st post and I've been a silent member on here gathering info etc. Ive bought my 1st mk5 gti last November using the ulez scrappage grant scrapping my old passat for 2k and adding my own money on top buying a mk5 gti. It's all standard apart from a res delete which the previous owner didn't even know. It's not fully speced out, but has a decent spec. factory xenons, washers in the bumpers, highline clocks, dsg, mfsw, rain sensors, auto headlights, cruise control. hasn't got sunroof, rear sensors or e/folding mirrors which I'm not fussed about. Long term plans is a major service belts, water pump, cam chain, vvt seals etc. Ive Already changed the oil, filter, oil pick up pipe and cam follower.








Tinted my fog lights with some glass spray tint and fitted some new open air grilles









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Members Rides / Re: Graphite Blue GTI Build Thread
« Last post by mk1_dave on March 26, 2024, 10:37:14 am »
Another update..

Have never liked the look of the original pole style aerial so picked up an original mk5 shark fin, sanded it and painted to match the lc5f paint. Came out pretty good and colour match is good.

I also bought a flip badge reversing camera as I knew I would have some of the trim off to fit the aerial. The reversing camera is really good quality and was pretty easy to install. You have to take off the boot trim, rear door card, some parts of the dashboard and of course the radio. I took the rear bench out at the same time so I could clean under them and would give me better access to get the door card out. The wiring was easy once you get the wires through the rubber grommet in the boot. I taped the wire to a cable tie then once I got a small section in I used some spray grease to help as the grommet doesn't have much space for the extra wires.

The badge looks much cleaner and has a drain hole that lets the water and dirt get out of the badge recess also comes with a rubber pipe to allow you to direct the water to the drain hole in the boot, if vw done this from the factory I doubt there would be as many rusty boot lids!

Decided to delete the rear wiper when I had everything off as I never use it. Ended up blocking off the screen wash pipe but I'm planning on buying one of the wiper stalks that came on the cars that don't have a rear wiper then this will solve the issue of accidentally hitting the screen wash.

Next on the list is new speakers, an amp and a new front bumper if I can find one in Scotland for a decent price.

Still not a fan of gloss black wheels but here's a couple of updated pictures of how the car sits at the minute.












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