just1crazye

If it requires a new turbo cuz its connnected then what is the biggest turbo I can bolt on (no sarcasem needed). The more boost the better starting around 4000rpm. Is the TO4 the best for the car or can I go bigger?

Phil type 951

yup.... see pic poster

Audi2ptzero

you can run high boost in any turbo, it is air volume that changes with turbo size.

A T04 will not make boost till 5K rpms on a 1.8t so forget about that. If you want boost by 4K then go with the APR stage 3 or the PES T28 kit.

johnAWD

You can't run 'extremely' high boost on a teeny tiny turbo. Physics comes into play once the compressor wheel is spun outside of its efficiency range. After that it turns into a cavitating heat pump.

True - it's all about flow. But if a guy wanted to run 25+ psi of substantail flow on a regular basis, then the tradeoffs have to be made.

Audi2ptzero

but it is only going to do that at low rpms since you will hit full spool real fast and that is when the boost will fall off fast. The more boost you ask for the faster you hit full spool which also means the boost will fall of even sooner in the rpms.

I just had my k04 dyno'd and when I turned up the boost my tq readings went up fast down low and the tq/hp peaks dropped further down in the rpms.

The test was on my 2032cc K04-15 running 14.5psi and 18psi on a standard K04 chip, 91 octane for a standard 9.5:1 compression motor, but I have 8:1 compression so the adv timing is about 5-8 deg too low. Looking to get the car tuned in about 2 weeks right after the new year.

johnAWD

Yeah - making the boost vs holding it is a whole 'nother story. These teeny turbos might be able to make 25psi for a second, maybe 2. The parts are just too small to build & hold big boost.

I was able to make & hold 30psi to redline in my last car, but there was the spoolup lag penalty to pay...

Audi2ptzero

The main problem is that the K03 spools up so fast and makes more boost at lower rpms and for that it is only going to hold 20psi for about 3k-3500 before it starts to drop off. Same goes with a larger turbo like the GT25 or T28, it does not hit full spool up till about 3500 rpms and if you could run 30psi and run your rpms to 9K rpms you would find that it would start to die off by 7k rpms.

Turbo size is a give and take, too big and your dead in the water at low rpms but makes alot of power at high rpms, with a small turbo you get great bottom end and midrange but no top end. It is all about finding where your going to live in the rpm range and knowing when a turbo is going to be too big for the rpm redline you have. This is one reason we dont put T04E's on a 1.8t since you have a 8K rpms max and that means if you wish to push it that far the T04 is only going to make real power from 5500-8K rpms, not really ideal is it.

johnAWD

Wow - that's impressive. Were you watching EGT and/or IAT? And I'd have to guess that you've got a front mount as well. Pushing the K03 that hard just seems wrong to me.

The car in which I ran 30psi was a supra. I used a turbonetics T66 which started making boost around 3600-3800 and was at 30psi by 4600 or so. The volume of exhaust gas was sufficient to get it spooled up early enough, but I also paid a top end penalty for using a smallish (.70 A/R) turbine housing.

I'm thinking that a t3/t4 setup would be ideal for the 1.8t motor, given that the exhaust is opened up and flows well..

What are the stock cams good for? Is anyone having luck with head work on the KO3?

Audi2ptzero

was done with tuning for 100-104 octane fuel. At this time I am pushing a K04 on my race built 2032cc motor which I also just dyno'd at 191 at the wheels on a standard K04 chip for 91 octane even though the chip does not have enough timing to burn that 91 octane right because of my low compression on the new motor, I am able to run 87 octane on that chip. The 191hp/207tq was done with 18psi of boost but I should get another 20 hp/tq once the chip is tuned for 91.