VTT GC Lite Flex Fuel - 91ACN / E30 / E50

[Chris@VargasTurboTech]

Hey guys wanted to share some results. This car belongs to a customer who brought in his 2007 335xi for turbos and a lot of maintenance work. His goal was usable power on a VERY basic set up, he even wanted to keep the stock catted downpipes (we advise/advised against it, but agreed to it). Once we got everything installed and working, we got the car on the dyno for some tuning using MHD. We started with a base map Justin (V8bait) had given us quite a while ago ran it through the FF map creator and made the changes required. We ended up with about 6 revisions for this particular tune. Most of those revisions were due to finding errors in the map on things like cold start(no fault of Justin's, just being an old bin it needed some love). Once we switched over to ACN91 (garbage fuel), we did 3 more revisions reducing timing to keep corrections reasonable.

We started tuning on E30 added enough E85 to get E50, then using Pro-Tool and the prime fuel pump function we drained the tank as much as we could. Our ACN 91 has about 10% Ethanol in it we have tested it and found up to 15% at times. Using the prime function you can never get all the fuel out. We ended up with the sensor bouncing between about 15-17% ethanol.

Mods are as follows
2008 335XI 6MT
Stock motor
Stock head
Stock intake manifold
VTT GC Lites
VTT Aluminum outlet
VTT stock location Silicone inlets
VTT DCI
5" intercooler
NGK plugs gapped to .20"
Delphi coils
VTT Crankcase breather
Spec 3+ Clutch
3.5 bar map sensor
PFS Single Shot bucketed LPFP
STOCK HPFP with 80K on it
No fueling aids of any kind
Motiv Flex Fuel with V8bait base map
XDF with HPFP tables
X-delete used for dyno

Dyno numbers were as follows with a minimum of 3 runs on each fuel type

ACN 91:
Best run 463.23WHP/513.51WTQ
Average of all 4 runs 456.17WHP/512.26WTQ

E30:
Best run: 523.03WHP/531.05WTQ
Average of all 3 runs 519.49WHP/534.71WTQ

E50:
Best run 548.08WHP/566.16WTQ
Average of all 3 runs 547.08WHP/568.46

Spool is as always insane on the GC lites, 500WTQ and full spool by 3K on the dyno will equate to full spool by about 2700 on the street. With the XI turned back on this car will be a rocket.

No changes were made to boost or timing between the E30, and E50 runs; we let flex do its magic and interpolate between the two tables to get us what we needed. As you can see on E50 the HPFP is maxed, it is just enough to provide clean runs, but we recommended to the customer if he plans to run E50 he needs a shotgun or PI.

Flex is pretty cool seeing the power differences with no tuning changes. For ACN 91 we actually did go back in and drop timing almost 4 degrees in the base table, despite that it ended up making more power because it cleaned up the corrections. ACN91 really does not like much over 4 degrees past 20 psi.

All in all for stock catted downpipes, no fueling aids, and a basic real-world flex set up, over 460WHP, and 500WTQ on garbage ACN 91 is quite solid. On 93 with timing bumped back up into normal range 500WHP on pump gas would be most likely accessible.

We can't wait to get it back to the customer!

Pictures are as follows:
Best ACN91
All ACN91
All E30
All E50
All Runs

Some logs are also attached for those that want to look closer.

 

[berns]

Awesome graph and numbers. Must be so fun on the street!

 

[fmorelli]

I love seeing this. @Chris@VargasTurboTech as always, thanks to you guys for sharing real info and hard data!

Filippo

 

[Asbjorn]

[...]

ACN91 really does not like much over 4 degrees past 20 psi.

All in all for stock catted downpipes, no fueling aids, and a basic real-world flex set up, over 460WHP, and 500WTQ on garbage ACN 91 is quite solid. On 93 with timing bumped back up into normal range 500WHP on pump gas would be most likely accessible.

Best ACN91

View attachment 33855

Thanks for sharing. I just wanted to support this data with some real world experience, having run GC lites for more than a year mostly on track.

My Z4 dct does 100-200km/h in 9.3s consistently with the lites producing 17-18psi of boost in combination with 5-8 deg of timing on Chinese RON98 fuel with race catted downpipes. This through a conservative tune developed for track use and higher iats - ie not a drag tune.

As far as I can tell, this is almost as fast as an equally heavy M4 CS with 460ps/446lbf, which was reported to do 100-200 in 9.2s. An M4 CS of course runs higher boost, and is arguably also what could be considered a "race" catted car.

Virtual dyno w/ dynojet correction below. Blue is cold turbos (day log), red is hot turbos (evening log).

Log (map not 100% final, but close)

Hide legend Reset zoom

I initially picked the GC lites due to the headroom they offer, as my intention was and is to run them hard lap after lap at M4+ power levels. For cars that only see street use I would recommend running them with better fuel at higher boost or simply getting smaller turbos. For street use, they are a bit oversized for my power level.

The GC lites sound best with OEM down-pipes or a four cat race setup. Other than that they are just a blast, both on street and track. GC lites are an awesome option in its power segment, and I wish there was more development towards this "spool is king" segment.

 

[jts1981]

Great to see Chris!!


Damn I need to get my tune finished