I made some good progress toward moving on from the FrankenTurbo F21’s to the TTE 550’s. Engine was removed along with the driver side FT21. I’m hoping to have the second FT21 removed today so it can be shipped back to FrankenTurbo for some porting of the turbine housing. (We’re interested in seeing if there is an affect on exhaust side back pressure with porting of the turbine housing). These will come back for additional flowbench testing in addition to another run on the S4.
One FT21 removed
In order to recycle my coolant I collect it in the rectangular box (1), transfer it to the plastic jug (2), and then run it through a coffee filter back into a coolant container (3). Because the filtering process takes a while I have two going at the same time and refill the funnel when I have a break doing other tasks on the car.
I now have a LOT of data to go through and make sense of. Here are the results from taking my S4 equipped with FrankenTurbo’s F21 mixed flow turbochargers to the Dynojet I have logged my car on previously.
FrankenTurbo F21 Dyno Session
The car was evaluated with three tunes, thanks to Daz for his assistance with getting all three of these together. As in the past timeliness was more critical than thoroughness, I needed to get the car on the dyno and was less concerned with having a smooth tune and more concerned with getting to a point that the car could be dyno’d and logged.
The tunes respectively 1) boost to 27 psi and hold 27 psi, 2) boost to 27 psi and taper to 24 psi, and 3) boost to 23-24 psi and hold approximately 22 psi. The third tune was intended to roughly simulate the boost profile used with the K04 tune I dyno’d previously.
F21 Results
Here are the power and torque results with the F21’s.
Turbocharger compressor outlet temperatures at 22 and 27 psi:
FrankenTurbo F21 Turbo Compressor Outlet Temperature at 27 vs 22 psi manifold pressure
K04 boost comparison
Here are these results compared with those from the BW K04’s.
This is how the boost profiles matched up:
K04 vs F21 Boost Profile
And the dyno results:
FT21 vs K04 (K04 Boost Profile)K04 vs F21 Dynojet Wheel Torque
The chart above illustrates the low end strength of the quick spooling BW K04’s.
The point of this comparison at equal boost levels was less about how the dyno numbers would turn out and more about being able to collect temperature and pressure data with similar tunes.
All boost comparison
The following comparison is of the K04’s versus F21’s when operating the F21’s at a boost level more in line with what can better take advantage of the hybrids features.
Here are the boost profiles of K04’s and F21’s:
K04 vs F21 All Boost Levels
Dyno results with the F21 low boost pulls removed.
K04 vs F21 Dynojet Wheel TorqueK04 vs F21 Dynojet Wheel Horsepower
FrankenTurbo vs K04 Peak DynoJet numbers
If the F21 tuning had been optimized, based upon the dyno results obtained today, this is how the F21 might compare to the K04.
Composite F21 Results
Green lines are for the BW K04’s.
Further comparisons
Much more data was logged on the dyno as well as the street and I will be going through that information to try and draw some conclusions about the attributes of the F21 versus those of the K04.
Comparison of the Intake Air Temperature after being conditioned by the Silly Rabbit Motorsports SMIC’s and TorqByte CM5 Water-Methanol Injection system.
K04 and FT21 DynoJet dyno Intake Air Temperatures
I’m very pleased with these results, especially considering they are occurring on a dyno.
Repeating what I said at the top of the post, I have LOT of data to sift through. Weeks of tuning on the K04’s and then F21’s have generated many logs.
Here’s one example of a street log to contemplate how it compares to the dyno logs from above.
The first time I got on the accelerator with the F21’s my first thought was, where’s the boost? It took a couple of moments before the turbochargers began to spool up, and when they did very quickly I was thinking ‘whoa too much’ as I was letting off the gas and my boost gauge needle swung up somewhere between 25-30 psi.
I thought that perhaps since this was the first time that I had got hard on the gas that the PID for the N75 had not had time to develop appropriate correction values for the wastegates on the F21’s that are set to a preload of 14 psi.
I also needed to temper my expectations as I had just come off driving for a several weeks with the Borg Warner K04’s, a turbocharger that I knew to be faster spooling than the F21. I was also on the initial tune for these turbochargers and possibly the apparently slower boost onset was an intentional result of the first tune.
The second time that I got on the gas I did so at a slightly higher engine speed which shortened the time for the boost to build, not like the K04’s, but more quickly than the first time. I also allowed the boost to build a bit longer, anticipating the N75 to kick in and taper the boost. As my boost gauge pegged at 30 psi I quickly reconsidered the likelihood of the N75 kicking in and opted to let off the gas.
It was clear that the tune was not yet controlling the F21’s as needed so I stopped try to record any further boost data.
The first drive has been inconclusive. I cannot tell if the perceived slow boost onset is attributable to the tune, a potential hardware problem, a bias from having just driven the car with K04’s, or is just a noticeable delay as compared to BW K04’s.
