Tuesday, September 23, 2014

Project Dragon Update #7: Extreme Track Test

We headed back to Spring Mountain for two more days of track testing on Sept 5th & 6th.  We wanted to see how the Dragon would fare in extreme heat with a pro in the car.  Testing in these conditions will ensure that clients have a reliable car on the street or track.  I drove it on the first day and we had our pro, Dave, run her on the second.

I drove the car on Friday to shake it down and confirm some of the fixes from our last track day.  The car ran well with acceptable oil pressures and coolant temps.  Coolant temps hovered around 206degF while on track and creeped up to 212degF when I exited the track without a cool down lap.  The oil pressures also looked very good with the lowest #s seen at hot idle (~14psi).  The PCV was vented with a foam filter that made a big mess and ended my day after 50 miles of track time.  I rigged up a catch can in anticipation of the next day.
On the second day, we ran the Mansell course.  There are two corners at SMMR called Pahrump 1&2 that are excellent oil starvation corners.  In fact they are so good that GM modeled these same corners at their Milford Proving Grounds back in MI.   See image above.

Dave Thilenius rolled in Friday eve so we could get a start on Saturday morning.  Dave is our pro driver and IMSA champ, who many of you already know has tested many of our cars.  We experienced ambient temperatures from a low of 88degF up to 102deg F in our last session.  Ambient temps really dictate how cool a car will run and higher temps will challenge any car run on track.  Dave ran several sessions, starting with a 3 lap session to learn the car and get her warmed up.  The Mansell configuration has some straights that allow the Dragon to really stretch its legs.  

We ran 113 miles on the car over the course of several sessions.  Dave averaged about 208-209 degF Coolant temps and Oil pressures that averaged about 29psi.  Dave got her up to 149mph on a couple portions of the track.   The fastest lap that he managed was a 2min31s lap.  This came during the first hot lap in our last session.  
During that last session, Dave accidentally shut the car off - we positioned our ignition switch a bit too close to the gear lever.  The chart above is from the point that he fired the car back up until he came off the track.  This session was also the hottest ambient at 102degF.  You can see that the peak temps we experienced were about 212degF.  This was a 10 lap session so we are happy with the cooling capacity of the car.  Oil pressure also proved to be good.  The data shown below is also from the last session.  I've circled the areas that define oil pressure in turns Pahrump 1 & 2.  The lowest numbers come during heavy braking but the engine is not under load and frankly we are still above the minimum specs recommended by GM at that rpm.  The car is running Toyo R888s and has no aero.  We will test again with slicks and wings.  A Daily Dry Sump solution has already been developed for the car and will be recommended for cars running heavily on track with slicks and wings.  I believe as is, the car is suitable for occasional track days - though heat management is still an issue that caused us some headache.

We intentionally ran the car with the factory cats that come with the eRod package.  This car exists because of the smog compliant powertrain package.  We know there are clients that want to register the car in certain states that require kit cars to meet smog tests.  I felt that testing the car, in a smog compliant state, was critical.  Frankly, we will recommend that anyone that is focused on trackdays should consider a decat.

The heat generated by the exhausts system (especially the cats) created some more collateral damage.  The balljoints in the rear arms were beginning to leak,  The trans cooler was located too close and resulted in hot trans fluid.  This caused the car to shift very poorly in the last session.  We will upgrade to higher weight trans fluid to combat this issue.  Though better heat shielding is a must on this car.  We have some work to do but it is a straight forward issue to solve.

At the end the day, the car inexplicably stalled and would not restart.  We thought we may have locked up the engine.  We dumped the oil, checked the spark plugs, scoped the cylinders and even ran a leakdown. Everything looked fine.   No issues with the engine.  In fact she started right up after cooling down.  We suspect the starter may have overheated and refused to crank over the engine.  Heat shielding is an absolute must...Palatov have actually sent us some shields that will solve some of the issues.

Watch our quick video:

We also took the time to test out some of the various suspension settings offered by the novel bell crank set-up.  Ultimately we found that the softest settings were best and we ran the best time with that configuration.  Thorough performance tuning will come at a later date.  This was our first stab at it but not a comprehensive one.

We will continue our development.  The quotes on tooling for the Spyder body, shown above are coming in now.  We continue to press ahead...

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