DASC Build Thread

[Christian]

I installed my DASC about four years ago on my 4 cylinder Z3 and have been tinkering with it ever since. I've finally completed all of my planned upgrades and had the car custom tuned. I've learned a lot from reading this forum (the Z3 and Ti have more in common than most people realize). Hopefully this thread can be helpful to others on the board who are looking do additional upgrades to their supercharged M44 powered BMW's.

Note: Before anyone tells me, I'm well aware I could've just swapped in an S52 and made more power for similar money. I probably also could've pieced together a custom turbo kit, but at the time I started this project I lacked the skills required to do so. I liked the idea of trying to find the potential of the supercharged M44, and I enjoyed working on this project as much as the outcome.

When I first installed the DASC the car was stock except for a open element paper air filter and Supersprint exhaust. After the DASC install I almost immediately installed Technique Tuning Stage 3 software and a 3.6" supercharger pulley. The car was initially running very rich, and put down only 162 HP on the dyno. Not nearly what I was hoping for. After replacing some vacuum lines and ignition coil packs, the car put down 180 hp in 95 degree summer temps. Better, but still not what I was hoping for.

Engine info at time of initial dyno after DASC installation:
- M44 internally stock w/ 70K miles
- Technique Tuning Stage 3 software (includes 3" HFM and larger fuel injectors)
- 3.6" supercharger pulley from Pulleyboys.com (9 psi boost)
- open element paper cone filter
- Supersprint exhaust

Initial dyno run after DASC installation. Not very good.


In the years after the supercharger installation I completed some additional mods. They are listed below, in order of completion.
- new OEM ignition coil pack, Magnecor plug wires, NGK V-Power plugs gapped to .025"
- Grounding kit (trying to fix and intermittent misfire)
- Sachs clutch for E36 M3 with Fidanza lightweight flywheel
- Removed traction control "throttle body" and replaced with straight 3" tubing
- K&N cone filter with home made aluminum heat shield
- Big bore throttle body from Maxbore.com with ported intake elbow
- Removed secondary air pump and made simulator courtesy of instructions by xxxJohnBoyxxx
- eBay 4 into 1 long tube stainless header (Supersprint replica) with heat wrap
- High flow catalytic converter
- Custom 2.5" diameter mandrel bent exhaust with Borla mid muffler and Remus rear muffler
- Ruff under drive accessory pulleys (water pump, alternator, power steering)
- Snow Performance Stage 2 MAF Boost Cooler water/methanol injection kit with solenoid valve (injects in intake elbow just before blower)
- Ported intake manifold to match intake manifold gasket
- home made 3/8" thick phenolic spacer between cylinder head and intake manifold
- 3.4" supercharger pulley from Pulleyboys.com (10.5 psi boost)
- Relocated intake air temperature sensor to intake manifold using custom machined and welded bung (to allow the DME to read intake air temps after the supercharger, and after water/meth injection.
- Added catch can after PCV valve to keep intake manifold clean and oil free

Overall engine view


Phenolic spacer barely visible between intake manifold and head


Relocated intake air temperature sensor


Intake heat shield


Snow Performance Stage 2 MAF water/methanol controller


Water/methanol nozzle injecting just before supercharger


The TT Stage 3 software was intended for lower boost than I was running, and the tune wasn't created to take advantage of methanol injection or any of my other mods. I spoke with Nick at Technique Tuning, and he thought he could do a custom tune that would increase power and keep the engine running safely. Before the tuning session I was really tempted to go with a 3.2" pulley to get 12+ PSI of boost, but on stock internals I didn't want to push my luck. Nick really knows his way around the DME, so I had a lot of confidence the custom tune would be worthwhile and could make good power even on the current 10.5 PSI of boost. Before the tuning session Nick warned me that his Mustang dyno would read low compared to the Dynojet dyno that most local tuners use, but for his purposes of part throttle "street tuning" he felt it was better.

I took the car to Nick's shop on October 13th. Ambient temps were 84 to 87 degrees. He ran a baseline dyno pull and the car ran to 185 HP before the AFR's suddenly went very lean. Nick found this was a limitation of the HFM (mass air flow sensor) and the fact that the DME didn't recognize as much airflow as my engine was capable of. He removed the HFM limit and the car immediately made almost 15 more HP without the AFR's going too lean. Next, after analyzing the dyno graph and AFR's, he was able to determine that the engine was losing significant power when the methanol first started injecting. This was because the mixture was going far too rich, so he leaned out the mixture in the midrange, which took care of this power dip. We then fine tuned the point when the methanol injection started spraying by monitoring intake air temps over successive dyno pulls. Lastly, Nick spent an hour or so fine tuning the mixture and ignition timing. At the end of the tuning session I had 207 HP and 170 FT/LBS torque. Even more impressive to me is that I gained power EVERYWHERE throughout the power band--at some points almost 15 FT/LBS of torque. I gained over 10 FT/LBS as low as 2000 RPM. Lastly, after he was happy with the tune, Nick adjusted the DME to pull out a lot of ignition timing if the intake air temps suddenly spike, such as in the event of failure of the water/methanol injection. This is a great safety feature in my opinion.

Baseline run (with my current mods) vs. final tune


Overall I'm VERY happy with the way the engine feels. Power is very linear, and the car feels strong at any RPM. It was well worth the cost of the tuning session. My peak power may not be any higher than some other modded supercharged M44 powered cars, but I'm really pleased with the feel of the car, the low and mid range torque gain, and the fact that I know the engine is running safely. My car only weighs 2,700 lbs, and it now has plenty of power to slide the rear end around when driven hard. Unless my motor ever needs a rebuild, I'm pleased to say I'm done with engine mods.