Front uprights

This week my EliseParts race front uprights arrived. Excellent service from EP as always, they even threw in a couple of camber shims in for me as these uprights have additional material removed from the shim face in order to run more negative camber than is possible with stock uprights.

The main reason for running these however is that they lower the axle 40mm by re-positioning the hub within the upright. This is by far the best way of lowering an Elise/Exige as it keeps the wishbone angles and roll centres as per how they were intended by Lotus.

To go along with the uprights I've replaced all the M10 and M12 nuts on the front and rear ball joints with Grade5 Titanium items. This saves an extra 100g of unsprung weight! :-)

Polycarb hatch update

Carefully painted a black band around the outer edge of the hatch:

 

Unwrapped the masking tape and cleaned off all residue, being careful not to add any scratches (WD40 and a soft cloth works well here).

I also added a 10mm self adhesive foam strip along the trailing edge of the roof panel. Then mocked up to the car again. 

Really happy with how it has come out. Yes there are some small gaps, but with the nature of the way I've "cut and shut" the rear clam these are probably as small as I could have ever hoped to get them. For a track car it is certainly looking more than passable now! :-)

Cooling & engine systems test

Quite a wordy post this one, very unlike me! Anyway bear with.. ;)


So this morning I managed to bring the Pierburg EWP to life. Despite being designed for a PWM input signal it is possible to run it without. Simply apply 12V to Pin #1 and #2 and ground pin #4 and after a delay of around 5 seconds the pump will run at maximum output.

After sorting a minor leak on the block where I hadn't compressed an O-ring correctly, all seemed well and I topped up the system and ran it flat out for an hour, pausing occasionally to check the radiator top hose bleed nipple for any air.

The system took a total of 11.5 litres which is quite a lot more than I was expecting. None of the hose runs are excessive so the extra must be in the 56mm core radiator and the Ferrari block and heads.




For some comparisons on EWPs I found a very useful post from a chap with a bi-turbo Merc V12 engine on mbworld.org:

Hi All, I've been getting interested in uprated IC pumps for my V12TT, and I've written a lonely mini-blog in the M275 V12 Bi-Turbo Platform forum for a while. I've been scooping up all the information I can find out about pumps, and put it in one place where each pump can be compared on a comparable basis. I've just added the Pierburg pumps to that comparison, and I thought anyone reading this thread might be interested - well, more than the M275 regulars, at any rate. This is what I just wrote over there: 

Understanding Intercooling, Charge-Coolers, Heat Exchangers and Circulation Pumps

These are probably best know as "The BMW pump", but its actually a range of pumps for different applications. They range from the 15W WCP circulation pump (for heating and cooling when the engine is off) to a 1100W monster to replace the biggest mechanical pumps. An electric pump is still a bit of a novelty, but following BMW's lead, I think they're likely to become commonplace. There are probably four of interest: 

CWA 50 . Circulation pump, 50W , 6000 rpm, 24 lpm @ 0.60 bar
CWA 100 Circulation pump, 100W, 7200 rpm, 30 lpm @ 0.85 bar

CWA 200 Coolant pump, 200W, 4500 rpm, 120 lpm @ 0.45 bar
CWA 400 Coolant pump, 400W, 10000 rpm, 150 lpm @ 0.80 bar

The CWA 50 is used as a charge cooler pump on the recent BMW V8TT engine, and the CWA 200 is used as the coolant pump on a wide range of recent BM's. The circulation pumps have relatively low flow and high pressure, while the coolant pumps are obviously high flow. Like all good pumps, they're specified by their flow rate under pressure, so we know what their installed performance is going to be. Contrast that with the Meziere WP136S, which simply claims 20 gpm/76 lpm open pipe. I don't have much information about how the WP136 performs in an IC system, so I used what I could find. Like the Meziere, the big Johnson and Davies Craig pumps also claim high open pipe flow, but when I put the Pierburgs onto my Flow Characteristics chart, an interesting picture emerges. 

For the purposes of charge cooling, these pumps rock. If you look at the Charge Cooler Resistance curve, which gives an indication of the pressure/flow characteristics for a typically constricted charge coolersystem, you can see which pumps will give good installed performance. The CWA 50 beats all-comers so far, and the 100 is better still, even achieving one bar pressure differential at low flow rates. For charge cooler systems, these are two meaty pumps. I believe the CWA 100 is what Renntech use for their new IC pump, and it seems to be exactly what's needed. Shame about the silly price. 

The CWA 200 & 400 coolant pumps are off the chart, flowing over 100 lpm, and I didn't even try to plot them. They're huge, but you can see they meet different requirements. Where the 50 & 100 (like the Bosch pumps) fit the Charge Cooler Resistance curve pretty well, the 200 & 400 are closer to the Engine Resistance characteristic. In fact, the Pierburg stats tend to back up what I've supposed are the installed characteristics for IC and engine cooling, with a big difference in the pressure/flow curves. If anything, I think the differences should be even greater, with an even steeper IC curve and a shallow coolant curve. 

The other thing that's interesting about the Pierburg pumps is that they facilitate electronic variable speedcontrol. They can be slowed down almost to a stop, for fast warm-up and to save electrical power. In theory, they can control water flow well enough to avoid the need for a thermostat. That might not avoidhot spots in the engine during warm-up, so I don't believe anybody has actually implemented that yet, but it sounds ideal for a charge cooler. 

So the CWA200 I have is off the scale on this chart, flowing ~115 l/min @ 0.45bar.

With the large rad, pump potential, and large air-to-oil cooler mounted on the splitter it is highly conceivable that I will be able to overcool the engine despite the large capacity and high rev limit. It that happens I can turn down the pump speed slightly, and potentially block off some airflow to the oil cooler.


Engine systems:

So I have now tested coolant circuit flat out for an hour @whatever pressure my system creates, tested fuel pump flat out for an hour @ 3.5bar, and tested the dry sump oil circuit flows during cold cranking of the engine!

This is really all the 'due diligence' I can do without a running engine to generate proper temperature and vibration, but I still count it as valuable. I picked up on both a minor fuel and coolant leak during the testing, (which is the point of testing) and much better to find these things now as opposed to during the first rolling road day or shakedown drive...

Switches & Wind Deflectors

After much strife I eventually got the new switches working successfully.

From left to right:

1) Hazard, 2) Master Lamps On, 3) Screen Demist, 4) Front DRLs, 5) Rear Rain/Fog

Very happy with how they came out :)



Another area I have been metaphorically losing sleep over is the seal between top of window and roof. With the correct S1 seals no longer available from Lotus, or fetching silly money it was down to making something myself. 

I messed around with some D-section foam for ages, but couldn't come up with something I was happy with. So I changed tack and decided to try a wind deflector solution instead. I cut down some wind deflectors from a Megane Coupe and managed to get them fitting nicely with a tight gap to the top of the window as the door closes. 

As the car won't really be used in wet weather this should be sufficient to keep any mild drizzle mostly out of the cockpit!