Thursday, December 8, 2011

Lotus Dry Sump Testing 12/6/11

We have been diligently working on our drysump system for the Lotus Elise/Exige/211 throughout this year. Our last test brought out two issues to sort:
  1. Low hot idle oil pressure
  2. Excessive oil blow-by from the tank venting
We made a few changes to the system and brought The Art Car (akaThe Blue Car) to test at Willow.  We recruited our friend Jack, again (Thanks Jack !) to handle the driving duties.  Overall the results were good and we were pleased with them.

Since our last track test, we made a couple of changes to address the low oil pressure.  We changed the gear in the pump but that was still not enough.  So we then disconnected the oil cooler lines/radiators and added a remote oil filter.  The pressures still remained low so we began questioning the accuracy of oil pressure readings from the point in the block that we are measuring from.  As it turns out, our hot idle oil pressure was actually within Lotus spec. Lotus states hot idle oil pressure at 39 kPa min, which is 5.65 psi.  

We redesigned our tank to address the excessive blow-by problem.  Our original design allowed oil to creep into the vent line.  We had it remade by Petersen and reinstalled it.  Space for a tank is the biggest challenge but we managed to keep things tidy even with the new filter location.

One new product we also tested was a 7" muffler that exits above the diffuser. This muffler will be tested over the course of the next few weeks.  It sounded great throughout the test.

 The weather at 
Willow Springs Big Track  was on the other end of the temperature spectrum than our last test at Spring Mountain. The weather gave us a chilly 55 degrees with just a bit of wind.  Jack made several short runs (1-4 laps each) in the morning so we could check the operation of the system and ensure everything was working well.  We experienced very little blow by about (1/2oz) while oil temps were stable around 220-240F and most important the oil pressures were quite good.  We completed a quick inspection in the garage for leaks and car condition.  Everything looked good for a longer session.

  After lunch Jack ran a couple of longer 20 minute sessions for us and the results were very promising as well. We had a bit more blow by (approx 2 oz) in the catch can but nothing compared to our first test in September.  Oil pressure at idle remains low when rpms drop but were excellent at higher rpm where it is critical.  Oil temps rose to 240degF and remained stable throughout the entire 20 min sessions.  We obviously had a bit of help with the cool ambient temperatures  but were happy with the stability of the temps.  

Jack ran the car at moderate speeds per our instructions so we could load the system and monitor it carefully.  He did a great job and delivered very consistent laps.  Our syncros on our trans are giving up due to an overly aggressive clutch we had previously run earlier this year.  This made the 5th to 4th downshift much slower than it should be.  We could see this clearly in the AiM data with spikes in the rpms and oil pressures.

We reviewed the data back at the office with Bill Dailey and did not see anything that would make us change the current system.  Oil temps were good and oil pressure is fine.  We will add another oil pressure sensor to a spot suggested by Bill and compare the readings with the original.  We will then be ready to go hammer the car and see if the system can live with 10/10s driving.  We'll recruit our good friend and professional ride and handling engineer for this task....oh, and we have a Hewland Dogbox in transit that we need to assemble and test.

No comments: