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I have been looking into water/meth injection for sometime. Just trying to work out a more cost effective method at this stage. What puzzles me is that the intake temps are still quite high when cruising. One would think that the air flow through the heat exchanger will cool things down a bit.
I'm also unsure as to whether the iat is pre cooler or post cooler as there are two sensors. I believe it's pre cooler because the temps are quite high, but as said above, even at cruising when I'm on boost, it's at almost 50 degrees. Could be by design.
Regarding boost, I have seen that graph before and I've been puzzled myself. I'm using torque to log my boost pressures and I'm seeing 15.6psi peak at around 1900RPM. My tuner also ran some quick calculations based on the maps in the tune which produced numbers around 17psi.
Had a peek around forums as well and the general consensus is that these cars run just under 1bar of boost stock. So I'm actually not quite about what's going on with that graph, my peak boost is definitely before 2000 as well.
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The IAT on my Mk6 GTI (and my old Golf R) was on the inlet manifold just after the throttle body - therefore post intercooler. Not sure what the setup is on the 1.2TOriginally Posted by Kesh
Some discussion here about boost pressure. The Briskoda link seems to confirm your theory of 16PSI.
77tsi turbo
https://www.briskoda.net/forums/topi...rom-the-12tsi/
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Yeah that's one of the threads I read as well. Might ask john what his graph is suggesting.
The IAT sensor is built into the map sensor on the 1.2 at least, and there's two of them, pre and post. I guess the definitive way to test is to unplug one of them.
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Quite the story to tell from tonight tuning session.
We upped the boost to try and achieve around 18psi, doing small incremental changes on each run. Each time, we drove carefully for a few minutes then did a pull on the freeway, so we can see where and when the boost is peaking. On the 3rd pull on the free way, the car hits peak boost of about 15.3 psi, and then it stutters bad, and the dashboard lights up like a Christmas tree.
We check the code on torque pro, and it's a cylinder 1 misfire. We limp it home, misfiring the whole way. We take the plugs out, praying to all the gods that the tip hasn't broken off, none of them were which was a massive relief. We did see some chipping or wear, but we weren't too concerned, so we swapped the plugs from a working cylinder, and cylinder 1 was still misfiring.. Uh oh...
What made me even more anxious is that the spark plugs were due in about 3000km.
Later on, I swapped the leads to 1 and 2 and the misfired moved to cyl 2, an absolutely huge relief. Having read up on it now, it's quite a common fault, but for it to happen mid pull at peak boost, was a gut wrenching moment.
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Did some testing, my intake air temp readings I'm seeing are actually post cooler, so I'm not too happy with it, even if it is by design as the car is happy.
I will be combating the issue in a few ways in the near future.
1. I will be installing a new intake, this will likely make absolutely no difference to temperatures or performance, purely just for acoustics. It's a cheap universal one off ebay which I will modify for use on the polo.
2. Venting the bonnet. I'll be installing a large vent around the middle to the front of the bonnet to promote hot air to escape from the under the bonnet. This will also reduce the pressure differential between the front and back of the radiator, which will mean a more effective radiator, and theoretically, also an improvement in aero.
3. Meth/water is unlikely, will outline below as to why. I am looking more into a water spray for the heat exchanger. I have heard good things about the effectiveness of these sprayers. I have bought some misting nozzles and I'll couple that with a high pressure pump and see what the results are. I have no idea what to expect, but theory would suggest a reduction in iat.
I've chosen against meth injection for a couple of reasons. Firstly, it is rather complicated, and whilst doable, there is a lot of wiring, tee-ing and sensors to plumb in. Secondly and probably the biggest factor, is the design of the intake system. The charge air pipe is a non standard piece of plastic with no real flat surface which really limits the chance of a nozzle having a good seal when installed.
Pre turbo injection is quite a bit easier, however there's a lot of info to suggest that unless the mixture is properly atomised, there is a great chance that it can damage the blades of the compressor housing. Not worth the risk.
The cool thing is that these modifications are quite inexpensive and will put less stress on the engine for a given target, not a lot to lose.
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Hoping my leads will come tomorrow sometime. Been almost a week since I've driven the car. Meanwhile, my ebay intake arrived, so I wasted no time doing a rough install.
With the stock pipe coming from the cold side of the turbo, it is quite a tight fit, there's on flimsy bracket but I'll do for now.
Will have installed pics when I get home
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Did some more tuning today. Very happy with the results, it seems to be a bit lean on the transition from off to on boost. But I've put this down to just requesting high engine loads at too low an RPM, but for logging sake I did it anyway. Never the less, the car was still happy, didn't pull any boost as you can see from the graph so I know that there's no detonation happening.
Full boost is achieved at 2000RPM which I'm stoked about, but unfortunately, there seems to be a boost cap set at 1.1bar which is stopping me from getting 18psi like a lot of people have been getting.
3 very consistant runs, requested afr's match measured afr's well.
Only hiccup was finding that the air filter had come off at some stage.. So I'll have to figure out a way to tighten it more securely.
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A very eventful night.
After doing months of retunes, it feels like progress was being made, however there were some issues. The car was going into an enrichment mode where it was dumping fuel after 3000rpm for some reason. The car only managed a measly 55kw on the dyno. It's obvious that something had gone wrong at 3000RPM in the graph as it dips and refuses to climb.
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