GtI IHI turbo onto Polo Gti 1.8T

[sambb]

Hi all,

I'm getting all the bits together to fit a Golf Mk6 Gti IHI K03 to my 1.8T 20V in a Polo 9N3. To do so there are a few little things I need to do to the turbo itself to get it ready to go in. eg blank off the electric DV, fit a turbo muffler delete and because I'll be running a custom tune i'll be uprating the wastegate actuator.
I was surprised to see that the actuator spring seems to be only 5psi which is really light. So I was wondering for the guys that are running say stage 2 tunes on their GTi's, what kind of peak boost you are at and what does the boost curve look like as you move towards redline - holding steady'ish or dive bombing to half its peak? Also if anyone has gone past staged tunes and has fitted stiffer wastegate springs I'd really like to hear what you've experimented with.
thanks for any insights

sam

[Lucas_R]

My old Mk6 GTI which was stage 2 - peak boost was around 15-16psi @ 3000rpm and then it tapered down to around 12psi @ 6000rpm. This is with the stock K03 turbo.

Below is a snapshot of some VCDS logs i did not long after it was tuned. This was DNA Tuning stage 2 and i asked them for a tune that wouldn't fry my stock clutch so my peak boost is likely to be a bit lower than some other tunes.

[sambb]

Nice. Thanks very much mate. It does seem to hold its boost plateau quite well. Was that on a stock wastegate actuator or did that tune use a stiffer spring?
And what is the stock boost peak with these turbos?
I think on the 1.8T it'll need to be tuned differently to a 2.0L to get the boost coming when the turbo is seeing less gas flow from the 1781cc. Thats the reason why I'm thinking the 5psi spring wont cut it cos any wastegate creep will be a spoiler.
Good info - thanks again
sam

[Lucas_R]

I never physically touched or changed anything on the turbo or wastegate Sam - that was all stock in that regard.

Dont quote me - but i think the stock peak boost level on a 155kw Mk6 GTI is around 8-9PSI from memory. Most stage 1 and 2 tunes take that boost up to around 18-20PSI, but as i mentioned, i asked for a slightly lower output (16PSI) to preserve my clutch.

[sambb]

cool. thanks very much mate.

[h100vw]

Sam, the mk6 turbo has a fixed actuator. It's a poor turbo. I'd be looking at one off a mk5 instead.

[sambb]

Yeah thats why I was thinking about wastegate actuators - there's no way of adjusting preload with it. There's also only about 2mm of factory preload on it which seems like nothing when the spring is so soft. So yeah I'll probably weld a longer shaft onto my turbosmart IWG75 which gives me a choice of 5,7,10 and 12psi springs. I have seen that they had all sorts of dramas with rattling wastegate flappers etc. Mine does seem to be tight on the flapper though and the turbosmart will use a different clevis to meet the flapper arm so hopefully that'll be ok.
Gav I did look at the ones off the MK5's but their compressor outlets looked a bit unworkable. This model and the K04-064 look to have the comp outlets in positions that line up very well with existing piework and the comp inlets look easy too. To be honest I got this turbo dirt dirt cheap and its practically brand new. Aside from the wastegate issues how else are they flawed?
I'm just looking for something that's an upgrade to my K03s that my stock rods can still tolerate and once that's done then I'll have all the fit up hardware in place which'll make a future upgrade to the BW K04-064 a plug and play proposition. From what I can gather it'll perform roughly the same or better on a 1.8T as a sorted K04-023 would but with lower EGT's so if that turns out to be true I'll be happy. But yeah I'm all ears if there's anything else I'm missing. The electric DV will be deleted. I've been told the stock turbo mounted N75 gets a bit hot and unreliable so I think I'll look at running it in a remote location or even just using the 1.8T N75 instead.

[sambb]

I fond this posted by an APR employee on vortex.

Standard BW/KKK K03's' 1.8T:

COMPRESSOR

WHEEL

Inducer: 38mm
Exducer: 51mm
Tip height: 4.4mm

TURBINE WHEEL
Inducer: 45mm
Exducer: 38mm
Tip height: 6.8mm
Blades: 11

MK6 Golf GTI 2.0T EA888 Gen 1

IHI
6/6 Blade Cast Compressor Wheel & 8 Blade Turbine Wheel
40.2 mm Inducer / 52.5 mm Exducer - Compressor
45.0 mm Inducer / 41.0 mm Exducer - Turbine

As well as being a bit bigger in the wheels I read somewhere that the IHI K03 has higher tip heights and the ex mani and housings flow much more than the 1.8T K0 housings so hopefully that's true as well!

[LZY13B]

My mk6 gti stage 1 tune peak boost is 24psi and it spools up stupid quick quicker than my old stage 2 polo gti did not sure what the boost drops down to in the higher revs around 6k as I’m going too quick to look at the gauge lol

[sambb]

Hi mate. You had the series 4/5 RX7 didn't you. Good to see you're still in a VW.
Still getting the bits together.

I found electric DV delete blanking plates for like 20 bucks on ebay, just Holden/Opel Astra VXR ones that had the same turbo on their Z20LET. I can adapt my 1.8T N75 wiring to the IHI N75 easy enough as the plugs I'd cut off and had left over when doing the SAI and N249 delete are the same. I'll wait till I have the adapter plate for the 1.8T head and can do a fit up on my spare motor before I decide which turbo muffler delete i'll get. Still waiting to hear from any UK guys who have done this in a Polo to know if the brake master cylinder is likely to foul on the OEM turbo muffler 90 degree exit or not. Anyone used the Mamba muffler deletes on their IHI's?
Main thing is making sure that freeplay in the wastegate flapper is acceptable and then working out if I even need an uprated actuator in a 1781cc application. If I stick with stock I'll modify it so the preload is adjustable or go to a turbosmart/GFB/Mamba actuator if anyone has got one lying around for the IHI for a decent second hand price??