pudjnr69

Sorry, I should have added, I am running the larger crank pulley, so if you are running the standard crank pulley, you will most likely not need to change the top idler.

edz968s

Have now got the set up on, of a grooved head pulley and double sided belt. Running to 6psi now.
Will try the supplied S2 injectors this week to see if there is any marked improvement.

Jfrahm

Awesome. I need to locate a supplier that will ship these belts to the USA. I might try again running the longer double sided belt by moving my extra idler to between the alternator and AC. The switchback before the crank pulley might have been causing belt whip or the like.

Jfrahm

Also as regards SC head cooling, I thought about plumbing the cooling air outlet to the inlet side of the SC through an inline filter (like a paint sprayer filter) to make sure there is good flow. I might not boost enough for long enough to have problems overheating the SC head but it's still a concern.

pudjnr69

Jfrahm - You should be able to get the belt from any VW parts dealership. It may not be in stock, but they should be able to get it if you quote the part number. Mine had to come from Singapore to Australia.
Car is waiting for dyno tuning - all back together (still have an A/C issue to fix post tuning).
I will be travelling for almost two weeks from Sunday - so I will hopefully have news when I get back.

As per above - the VW 7-rib belt is about the right size for the standard set-up. If you go to the larger crank pulley - you will need to reduce the top idler pulley to compensate. With the larger crank pulley and larger alternator pulley - the 1710mm long belt was about 110mm too long.

Carl Fausett

Edz - before you swap injectors in, read the air/fuel ratios. You goal is to maintain 10.5 to 10.8:1 AFR at full bosst, your done.

All - a new cooling unit has been developed by Raptor that is both smaller and yet moves more air to cool the bearings int he Raptor. The first one of these new cooling units should be here in a week or so... its on its way... and I will post pics of it after it arrives.

Jfrahm

So far no luck, I think I might have to find a Euro supplier who will ship to the USA.

edz968s

Looked into this a lot. Without a dyno hooked up and relying on my a/f guage, I am getting into the higher rich segment of the reading once boost kicks in, so maybe there already, just thought the injectors would be ok with what I have now and adjust themselves accordingly via the ECU.
But since fitting the belt and grooved pulley there is a big difference now in performance, no belt slip and no belt dust either, so far so good, running well.

Carl Fausett

...and therein lies the danger. Yes, the ECU will attempt to automatically "tune" it - to 14.7 AFR as it is programmed to do. That is unacceptable for boosted applications, and the ECU does NOT know it has boost. It only can sense the increase in air flow but the stock system has no provisions for measuring and responding to the increase in manifold pressure and density.

To allow your ECU to "tune it" is very dangerous for anything above our stock Stage 1 kit levels. The FMU must be used to enrichen the fuel supply under boost. That's what it is for. Alternatively, if the ECU is removed and replaced with a stand-alone system that does factor in MAP (Manifold Air Pressure) like the TecGT kit we sell, then the FMU is no longer required (although even then it is still a good idea).

edz968s

Ok, so the FMU is the deciding factor in the increasd a/f mix, but what are the injectors that I got in the origional S2 kit for? Thought they where for increase fuel with the kit, improved 3rd generation injectors.
Would be interested to see the newer cooling set up also

Eric_Oz_S2

Carl,

From your post I assume you are referring to boost under part throttle when the DME goes into closed loop. I presume then that part throttle boost is not an issue with the stock kit boost levels but becomes an issue when boost is raised. At WOT the RR FMU would presumably compensate enough (with larger stage 2 injectors). The same problem can actually exist at throttle transition from part to fully open throttle. The problem appears to be the DME cannot enrichen the fuel quick enough at the transition when supercharged. In my case I run the "non-cat" maps on the track and this keeps the DME in open loop at all time and allows richer AFRs at higher load/higher rpm points on the PT fuel map. I think the 968 DME has some provision for running no-cat. The RR FMU would then compensate for both part and wot boost conditions. You also need to scale back the fuel maps as well by the amount your new injectors flow over the old injectors (without considering boost) so you don't go bulk rich in open loop PT. Perhaps worth a try with a datalogger attached. Obviously not emission compliant - but on the track that won't matter.

I have my "O2 off" switch from the DME connected to the wiper switch (wiper removed) so I can change on the fly. Works perfectly.

pudjnr69

There is an issue with the DME when running not in WOT driving the AF ratio back to stoic every 1/4 second. This will lean the engine out.

Eric_Oz_S2

Yes that is true - it defaults to closed loop in the PT maps and targets 14.7:1. It can be set to change the closed loop limits so it doesn't do this, but I have found it is easier to simply run in open loop on the track. Without a map change (or running open all the time) it can run lean for short bursts under boost. Normally though, there is only very marginal boost under PT (at least in the S2). The problem is when you nail the throttle and all that boost pressure is released and you are still running 14.7:1 for a split second. In this case my knock counter registers quite a few knock counts. If you start at something richer (around 13-13.5 for example) this problem is reduced (and knock counts are significantly reduced).

The 951 gets around this by having 14.7:1 ratios only at cruise and lower rpm and loads. It runs quite rich in the "lower right" corner of the PT fuel maps so the transition to WOT is much better.

Carl Fausett

Edz: if your air/fuel is good right now under full load and full boost, and the car runs good down low too - then you are done. Do not put in the larger injectors.

The larger injectors were sold to you as part of our Stage II kit which required larger injectors.

I have lost track of your current configuration because of whast seems like many many changes. Not sure at all what your running now. So use whichever ones provide the best A/F.

I hope your A/F gauge is not one of those ones with little LED lights or that just say "Lean" and "Rich" You need actual numbers. If it is one of those "Lean - Rich" types, you can "calibrate" it on the dyno, when you see 11:1 A/F is on the dyno, make a note of where that is on your gauge and use that as your reference point. Hopefully 14.7 will be straight up and down (it usually is)

Carl Fausett

Eric O2 S2: very good info for the others, thanks for sharing. I like the wiper switch solution. Clever. Good job.