06/20/08 A frustrating day for me. The drysump tank only half works - it certainly has cured any pressure drop in turns but it's spitting out oil from the vent on top just as bad as the old one did, maybe worse. So I basically got one lap in each session, saw smoke in the mirrors, pulled in, spent a bunch of time draining the oil, then doing circles in the parking lot to see if it still comes out, only to have a repeat the next session. I drained over a quart altogether, in several tries, and while things got better (couldn't get it to spill in the parking lot even after the first drain), the string of turns 4-5-6-7 would disgorge oil all over the exhausts and much of the left side of the car again. It's perfect on the street and it works in a parking lot but out on the track - no dice. So now I have to devise a vent/catch tank system that will actually work. No rest for the wicked.
As a consolation I took a few laps in Kermit at the end of the day. A very different feeling car after Bikini, definitely nowhere near the power and much softer suspension setup. But it's quite satisfying and I can drive it pretty much like I drive the Mini now - sliding around and adjusting yaw angle throughout a turn. It's fun :) Didn't get any lap times but it was a good relief for my frustration and that's what counts. Also M had a good time in the Mini so not a totally bad day overall.
06/27/08 After going through a number of possible solutions for the oil spillage problem, I settled on one to try - a labyrinth-type vent / oil-air separator. A bit of scavenging for parts, a bit of fabrication and there it is.
We'll see if this works. Of course on the street spillage is never an issue in the first place so I'll have to find a trackday where I can do some testing. It will require some planning and contingencies. Or just winging it :) There is also work to be done on mapping, the speedo still needs to be hooked up, ditto for the dashboard water temp gauge (the ECU gets its own sensor). No shortage of things to do. Earlier today I took a friend out for a run on the twisty road - Bikini never fails to impress in that environment. It hangs the tail out in 3rd gear at 3K RPM (out of 11). And 2/3 throttle bursts between corners feel like the initial rollercoaster drop to most. Now if only I can get it to work reliably on the track...
07/03/08 A ProDrive test day. Basically I went to all the trouble of getting a novice race license so I can have access to these days and so now indeed I do. It is open to race cars/race drivers only, there are usually only about a dozen cars and it's essentially open track all day. A little more than twice the price of a regular trackday but if testing is on the agenda it's a great way to do it.
Last weekend was ridiculously hot, right at 100F, and the weather ever since has been odd with alternating heat and thunderstorms (a rarity here). I looked at two different forecasts the night before, one said partly cloudy all day the other said showers and thunderstorms all day. At 4 am I was awakened by a spectacular thunderstorm and pouring rain but fortunately by 9 it was clear and dry, and it stayed that way from then on.
The major item to test was the new vent setup. Not wanting to take a chance without a catch can I modified my vent-cap design with a hose barb and a catch can on the other side. I also brought a lot of various materials, a few contingency plans, and Tristan to help me implement them if need be.
Larry is also out testing his Stohr F1000 - a very fast little machine powered by a 1.0L stock motorcycle engine. These run very near Formula Atlantic times.
Lots of other fun cars were there, including a CanAm Shadow with something like 1,000 hp and tires that looked to be over 2 ft wide. Unfortunately he only ran a few laps before suffering a tire puncture and his spare set was not mounted yet. So back in the trailer it went.
My day was not much better. I took a couple laps in the morning, pulled in to check the catch can and sure enough oil was spilling out. Several different configurations later the problem still persists. Moderately driven laps are fine but if I start pushing, the car spits out half a quart per lap until I start getting pressure drops in right hand turns. I even tried a setup with a T splitting to the valve cover vent, hoping that there is vacuum in the case and it would draw the oil back down into the engine instead of up and not up into the catch can. That didn't help. So I went out six different times and found six approaches that didn't work. Supposedly the WD40 product is so named because it is the 40th formula the inventor tried which finally worked. Hopefully my vent won't get to rev 40 but this is basically the nature of the development process. Make a stab at a solution, test, evaluate results, repeat. Not the most fun way to spend a day at the track but hey, I chose this. There are other glitches too - for some reason the tach in the dash freaks out if I go over 7500 rpm and swings wildly before parking at zero. Engine runs just fine all the while and pulls strongly to whatever unknown RPM it is (I'll have to look at ECU data logs for that). Once revs drop below 7K the tach gets its bearings and works fine again. I guess I'll have to contact the manufacturer about that. I did discover that the minimum oil level in the tank to avoid pressure drops is 3.5 quarts, so that much is good. I will now have to pull the tank back out, cut the top open and modify some baffling. Ugh.
Not all was a loss though. The video below (24M file) gives some highlights although I never got even one clean lap in. I was driving with my eyes on the oil gauges the whole time so it's still hard to say what the car is like except that when you floor it, it is fun! Quite tail-happy too but pretty controllable. Needs more shock for the spring rates (shocks are adjusted to max already, I'll look at having them revalved once the more pressing issues are put to rest).
Today we ran without chicane so lap times are not directly comparable to normal trackdays. The one lap where I was able to focus on the driving instead of gauge monitoring I did an easy 1:19.5 which is half a second faster than the best I've ever done on any bike including the R1 (no I'm not a terribly fast rider, it's only a point of reference). Since Bikini really is a four-wheel motorcycle it is interesting to compare it with a bike especially since bike trackdays don't use the chicane either. Below is a simple comparison of the 1:19 lap in the Atom vs a 1:21 lap on the 748. I only included speeds and time slip because g readings on the bike are not very meaningful due to lean.
The Atom can accelerate harder than it does but the bike is pretty much tapped out (it's only a 95hp motor). Both machines can corner a bit better too but the car definitely has the edge here.
There are a few interesting metrics. Max speed is 136 mph (still at only about 8K rpm out of 11 although now I'm guessing it'll top out at about 155), max cornering 1.3g, max braking 0.9g (lots more to go there and still being very conservative), max acceleration 0.6g (probably some more to gain there as well). The car is actually quite stable at nearly 140 mph and there is no buffeting. Whether that's due to the vortex generators I installed or not is the subject of a future test. In some ways it's frustrating to only get a taste of what the car can do, but it's still better than nothing and there's no way to even come close on the street. Just have to stay on task and solve the issues.
07/09/08 The mods to the tank are done, now I 'just' need to install it.
There are many changes, the most important ones are not visible - the baffling inside is redesigned to better deal with the fact that the tank is installed at 30 degree angle to the left. The tilt is by far the most difficult part of the installation - it makes a 1.5g right-hand turn look like a 4.5g turn as far as oil is concerned, and most turns at PIR are to the right. I am quite certain I would not be having these problems without the tilt but unfortunately the tight packaging of the engine bay leaves little choice - and no I don't want to hang the tank outside the chassis, even if it's 'blended in' like the Brammo solution..
Vent location and method has been changed and there is also a change in the overall plumbing. Previously, the scavenge oil from all 3 pump stages was routed through the cooler upfront before returning to the tank. Back before the engine first ran John Hartley had suggested that this routing may create too much backpressure due to total line length so I had installed a second pressure gauge in the manifold that brings all the lines together. Under most conditions the pressure remained under 20 psi which was OK, but after reviewing the video from the last test I noticed at over 8K RPM the scavenge pressure went as high as 40 psi which is a bit too high. Video is a good tool for simple data acquisition, as long as some gauges are in view of the camera!
In the new setup, per John's original suggestion, oil from two stages still goes through the cooler and the third stage returns directly to the tank. This required a second return fitting on the tank and the purchase of some additional hose and fittings. So now I get to take apart the old system, redo the hose ends (some may recall how much of a pain it was to assemble them in the first place!), and then put the whole puzzle back together. It will definitely be better, let's hope it's good enough to work at 1.5g ('4.5g').
07/24/08 It's actually been installed for a while but today I finally found some time to button the rest of the car up. I was frustrated by all the assembly and disassembly at first, but now there's something Zen about the steps necessary to complete the tasks and line things up just so. Ummmmm. Or maybe it's just the exhaust fumes. At any rate, the new oil system is in the car and ready for the next test on the 29th.
Clearances are the typical 1/8"+ that can be found throughout the engine bay. There is now a nifty oil drain valve on the tank which will make oil changes much easier. I even polished the burnt oil off the exhausts so they look nice and shiny now.
Another thing I did was finally install the electrical 'fix' for the dash. Brammo had sent it to me a long time ago - it's basically a 220uF electrolytic bypass capacitor on the dash power supply lines. It is supposed to fix some 'intermittent power problem' - if the dash freaking out above 7K rpm is it then maybe it's good, otherwise I haven't experienced it. Somehow I suspect there will be more fixing needed for the tach that doesn't quite go to 11. We'll see.
07/29/08 ARGH!!!! Today was supposed to be the validation of a definitive fix to the oil problems. I thought that the rain which started as we were going through tech was going to be the most irritating part of the outing. WRONG. Our new canopy kept the rain off the Atom well while parked and rain stopped quickly, giving way to dry track by the time the first Instructor session started. I did two laps to warm up the tires and just when the grip was starting to improve the car unexpectedly slides in the chicane. I catch it no problem but could I already have filled the 1 quart catch bottle to the point of spilling oil on the rear tire? I finish the lap but pull in on the next one. Sure enough, the catch bottle is full and the right side of the car is coated in oil including tire and brake rotor. DAMN.
I parked Bikini and focused on instructing. Drove the Mini for a session and then borrowed the Exige from Larry to run another one. The Lotus is fun but after the Atom it feels underpowered, although there is actually enough there to power-slide through all the turns. This is good because otherwise the car understeers badly. Reminds me a lot of the M5. We'll need to tinker with suspension and maybe tire choices to see if a more track-oriented setup could be devised.
Last session of the day I just had to take Bikini out again, without adding any oil (as long as I keep an eye on the pressure gauge it's not a problem). Only did three laps and the tires were still rather cold so turns were a bit sketchy but the straights - WOW. Can't wait to get this thing properly sorted so I can actually drive it for a full trackday. The power is addictive and the car just motors past everything like they're standing still. M was clapping her hands and giggling uncontrollably :) The second lap was a 1:28.28 and I know there is tons of room for improvement there. This is easily a 1:25 car, yes. I was noticing quite a bit of helmet lift at over 130 but no buffeting. Gotta make sure the chin strap is tight!
Those final three laps pumped out an additional quart of oil. This is extremely frustrating - I really thought I had it fixed this time and was prepared for maybe a little spillage but a quart every three laps is insane. What to do next? I'm thinking that I'll give up on trying to keep the oil from coming out the vent and instead focus on returning it back into the system. I've seen some commercial drysump tanks with integral catch tanks that drain back in, and aircraft have air/oil separators which drain to the sump so clearly I'm not the only one to have encountered this problem. The question is how do I drain the oil back into the system if the system is under positive pressure? A small electric pump would be one solution, I'm also looking at a few others. Ultimately I know the problem is fixable - it's just a matter of how long it will take and how much it will cost. So far, not so good.
08/12/08 The parts finally came in for my next attempt at an oil fix so I fabricated the drain-back tank and had Jared weld it up.
The new solution is a tube mounted as high as it can be in the car, with the vent being about 2 feet higher than the top of the tank. The tank itself is a 1.25" diameter tube - that's all there is room for and even that is tight. There is a -10 line draining down to a T in one of the scavenge lines where it enters the tank. I had to move the fuel pressure regulator to clear the lines, which required removing the seat... That's a good thing anyway since I have some wiring to do.
The hope is that the scavenge oil flowing by will draw the oil from the overflow down, or at least not prevent it from draining. The vent tube comes into the upper fitting and internally the inlet tube is bent to face down the 'tank'. If this doesn't work, I'm going to be at a bit of a loss. We'll see on the 25th of this month. For now I'm going to hook up a hose to a temporary catch tank from the vent but if nothing comes out it'll get a small K&N crankcase breather filter. That would be nice.
I also looked into the dash issue and basically it looks like I'll have to get a new 12K RPM one from SPA. They retail for around $1,400. UGH. But, given what I have in this car already, that's pocket change. And I might actually use the same dash for the dp1, especially if they can change the blue backlight to orange or red for me. I'm not a fan of blue backlighting.