Sams TFSI turbo conversion (maybe!?)

[Sydneykid]

yeah I think E10 will be set aside for the next fuel crisis and 98 will be the go on the street provided its not much more than 2 bucks a litre. This turbo with a brewed 98 RON/E85 @ E25 will be a rocketship on the next engine. Just didn't want to do it on this bottom end.

Gary out of curiosity does running ethanol heavy fuels cause MAF power estimations to skew. For example with E85, a large component of the oxygen that will be burnt is chemically IN the fuel and the fuel:air ratio is richer relative to petrol. So less of the O2 burnt will be taken in through the intake and the 'air' requirement is lower for a given amount of alcohol fuel. If so, does that mean that MAF g/s underestimates power on E85 cars? Or because there isnt actually that much oxygen in air, does the air measured through the MAF not actually change much?

Good question Sam, the simple answer starts with the stoich, at 1 lambda Pump 98 is 14.7 A/F whilst E85 at 1 lambda is 9.8 A/F. Around half of that extra fuel required (33%) is due to the amount of oxygen in the ethanol;. The other half is due to the lower combustion power of ethanol, as a result in order to get the same value of combustion we add around 30% more E85 (compared to pump 98 ). That's by weight (not volume) as ethanol has a slightly higher specific gravity. We can't overlook the inlet air cooling effect of ethanol, making it denser.

There's some complex maths at work, but simplistically at stoich in the combustion process there is 3.3% additional oxygen supplied by the E85 and there is 30% more E85, which totals 4.25% more oxygen. That's oxygen that doesn't get into the combustion process through the AFM. If running at richer than stoich then more than 4.25%.

Rear world about the same result, it's been over 10 years since I tuned a car on E85 that had an AFM. In general I used to see around 5% more power (E85 compared to Pump 98 ) at the same air flow meter voltage. That's just by setting the lambda for the E85 the same as Pump 98. So not a big deal. The real power increase comes about when you add the ignition timing and up the boost that you can't do on Pump 98 due to detonation.


Hope that helps
Cheers
Gary

[sambb]

Yep sure does. It just sort of occured to me during the E10 tuning that perhaps I needed to pay attention to the butt dyno rather than just maf values, because maybe the maf values were downplaying its success/or not. I remember seeing that mentioned when I was doing water/meth injection. ie the oxygen rich auxillary fuel is going into the airstream post maf so you wouldn't see all the engine power gained represented in the airflow through the inlet. It'd seems though that at 10% ethanol you'd never spot it and that even at E85 levels it'd be tough to claim that a lesser maf plot is actually making the same hp as a better looking plot because of some offset that the ethanol fueled car can claim in the maf numbers.
Well in my case I definitely don't think that the E10 plot was close enough to the 98 ron for that to even become an issue. 98 was definitely the less affordable winner.

[sambb]

So I think this is where I'll leave the TFSI turbo conversion thread. I finalised the intake the other day which has sort of ruled a line under it all. I'd toyed with the idea of moving the battery under the passenger seat and then going back to the standard airbox but but figured this way will be fine and probably breathe better anyway.
So all taken, on 98 RON fuel it made over 205g/s of air through the MAF on a tune that also wasn't looking for every last bit in the interest of keeping rods alive. With the very rough multiplier of 0.8 (which doesnt really take into account the effect of additional timing changes) that brings it to the 260 hp crank. That was when I'd deliberately had it without a cold air feed too. We were doing most of the tuning in some pretty cold weather. I simulated hotter conditions by drawing underbonnet air so that it wouldnt pull timing like crazy once summer kicked in. I think it'd be safe to say that if it'd had a cold air feed in those cooler it would have been cracking the 260hp mark pretty consistently. So at about the 195Kw crank mark, I'm more than happy with it. Best bit is that with the clutch LSD and some throttle control nearly all of that makes it into the tarmac so the car is pretty nippy when you're running up through the gears.
The other thing I would say is that turbo tech has obviously come a long way since K03s's. By going to this turbo that is standard on a 2L I always expected a bigger midrange surge and a bit more up top but thought for sure that I'd be giving away that K03s bottom end hit. I can honestly say that it is dead set equivalent down low yet has all the benefits up top. Yes, I'm running a 10psi base spring in the actuator and maybe it'd be a bit more civilised down low with a 7 psi spring and the ability of the boost control to intervene lower but I reckon you'd be splitting hairs. This car is also not running VVT as there is absolutely no need for it to infill any perceived bottom end loss. Its still a little boost freak just like K03s's. But in general its just an all round better package. The better breathing exhaust mani runners with less restriction into the hot side are a big part of that. I never have to worry about a glowing red hot side anymore and fried turbo gaskets and turbo bolts coming loose. The fact that that the turbo doesnt feel as 'big' as I thought it might makes me 100% confident that a Golf mk6 R K04-064 would be perfectly streetable on a 1.8L engine.
K04-064 donations welcome!!!! ha ha

[Water Boy]

Keen to see it in action next year mate!