aerobod - near CYYC

I’ve seen a steady 60C at. -5C ambient in my R400D oil tank when heading to events on dark spring mornings, but not as low as 41C. With the new R500 equivalent engine build I’ve put in a 12% lower speed water pump pulley to reduce over cooling, besides the lower risk of cavitation.

Most digital multimeters have a current limit of 10A and an internal fuse that will blow over that value, though, so the meter has to be chosen carefully when it is connected inline with the load.

A good temp range is 70C to 130C with a synthetic oil.

Also, don't forget to remove the slide bolt on the rear caliper nearest the bleed nipple to allow it to be tilted upwards for bleeding, (if not remove the caliper completely while the line is still attached, ensuring a block of wood or similar is used to stop the piston being ejected). You won't get an air-free bleed in the rear calipers if they are kept horizontal, the bleed nipple base has to be higher than any other fluid-containing area of the caliper.

The benefit of the dry sump tank oil temp is that you know that the oil is up to temperature and the oil that is being supplied to the main bearings and big ends is very close to the dry sump oil temp that is fed from the bottom of the tank where the sensor is located. Ideally two oil temp sensors would be used both the tank one and an additional sensor in the bottom of the dry sump at the finger filter.

Hi John, The characteristics of the thermistors used are similar across all the manufacturers, although the exact calibration will vary. The Bosch curve is similar with about a 1.5 scaling factor at higher temps compared with the Caerbont curve, but similar resistance at 40C - https://www.bosch-motorsport.com/content/downloads/Raceparts/en-GB/53687307119081483.html#/Tabs=53698955/

I’m of course forgetting the ECU temp sensor is not the same as the dash gauge temp sensor, so they will likely have a different calibration curve and resistance.

Hi John, my 2012 R400 has different coolant sensors for oil and water. The oil temp sensor is a Bosch type, the coolant temp sensor is a Ford type. The calibration voltage curve in my ECU at 10C shows 3.70/5.00V for the coolant and 3.96/5.00V for the oil sensor. The Bosch NTC sensor has a nominal 3,792 ohm resistance at 10C (which is probably within measurement and manufacturing tolerance for 4,500 ohms at 12C, my sensor would be 3,808 ohms if the calibration curve is accurate). This equates with a 1000 ohm pull-up resistor in the ECU to give 3.96V across the sensor. The Ford sensor would need a resistance of 2,846 ohms to provide 3.70V across it. Either I have a different Ford coolant sensor on my car or your sensor is somewhat high resistance. Did you measure sensor resistance directly at the sensor with the sensor wires disconnected?

I will test it with lots of high speed airstream this coming summer, John, then report back. Around 2500km of track use scheduled, hopefully at speeds up to around 185km/h with the new engine.

Gave the exhaust and headers a bit of a clean and repacked the silencer with 1.7m of Acousta-fil today, then fitted the system to the car. Assembly is now complete. Will bleed the clutch and do the annual brake bleed just before starting, when I swap to the sticker track tyres ready for a rolling road session. Need to get some more coolant and remember to get a container of fuel as I drained the tank last year. Waiting for a bit better weather over the next couple of weeks, once the snow from one of the snowiest Marchs melts.

Do you think it is stones from the front tyre that aren’t captured by the wings or just grit in the airflow hitting the leading edge of the filter that causes the ablation problem?

Today was the careful cutting of the hole in the bonnet for the air filter. Good Friday did turn out to be a good Friday 😀 The first task was to mask the filter and contact points where I was going to create a form to simulate the bonnet lines: Next I used some wire mesh held in position with a spirit level to form a profile of the bonnet around the air filter: I then used a plastic file folder as the template to lay over the mesh and gradually cut the hole in it to give about 5mm clearance to the filter, but using smooth curves as opposed to the exact profile of the filter that has bulges where the end pieces are joined to the main part of it. The template was then taped to the bonnet and the profile traced on to it: Dimensions were then re-checked and checked again, before bonnet was ready for cutting: A cutting wheel was used to pierce the aluminium. I thought about using it for the whole cut, but it was slow going: It was a lot faster using a hacksaw blade, only about 20 mins for the complete cut: The hole was then deburred with a file, ready for test fitting: As expected, a bit of adjustment was needed for about half of the circumference of the hole: Some plastic edging trim was added, including a short piece for the strengthening flange where it is close to the filter: I’m happy with the fit, it is pretty even around the periphery of the filter: Overall there is little room for putting the filter anywhere other than the position I used, perhaps 2 or 3mm leeway in moving it up or down by altering the vertical position of the holes in the filter backing plate:

I saw that thread about the filter wear, John. I’m trying to avoid running an airbox if possible, but depends on noise at the track, I have a 24 plate Supertrapp for the exhaust, so hopefully that is enough to stay below the limit (it was last year), without the intake pushing me over. If I do get wear like you experienced, I will probably end up treating it as an £80 consumable item, hopefully lasting a couple of years at least.

Hi Jonathan, The way I made it at the moment the bolts has to be at 90 degrees to the cable, as besides holding the clamping halves to the pedal shaft, it also holds them together. I would need a solid piece that goes over and is bolted to the tube, then a top bit that separates to hold the nipple with its own fastener. It would have to be longer than the current design to give space for the additional fastener, but would also risk interfering with the closed throttle stop bolt if too long.

Marked out the air filter backing plate, deciding that I need to drop the centreline a little below the throttle body centreline to give enough bonnet clearance. Used a 2” hole saw to cut the intake holes for the 48mm throttle bodies and 6mm holes for the 5mm horn securing bolts: I used a bit of RTV between the backing plate and throttle bodies and blue thread locker with Belleville serrated locking washers on the bolts. The intake air temp sensor is just visible in the backing plate between #1&2 intakes. Needed to cut a small angle on the bottom of the backing plate below #4 cylinder to give a bit of clearance to the diagonal frame tube below it: With the Jenvey DTH throttle bodies on the Duratec, the intakes are not evenly placed, being 97.5mm between #2&3 and 90mm between #1&2 and #3&4. Just as well I measured all of them instead of assuming constant pitch, before cutting the backing plate holes: The horn sticks out quite a bit from the body on #1: The underside of the bonnet should be around 5mm above the central air filter securing tab: Ready for measuring and cutting the bonnet hole next: The TPS was also fitted. The existing Econoseal flat 3-pin connector had to be replaced as the directional keys on the side were the opposite of the 3-pin connectors I had spare. The TPS also had a round Econoseal connector on it. I cut both off and used the Econoseal connectors I had on hand:

To remove slight rubbing of my modified throttle pedal cable end on the steering shaft and flange near the throttle stop, I modified the bolt used and added a couple of reliefs to the cable nipple holder, I also machined off 1.2mm from the pedal pivot bush to remove virtually all the lateral movement of the pedal: A couple of mm of the flange near the throttle stop was ground away and given a bit of paint: On full throttle the low profile bolt head clears the steering shaft by a couple of mm:

I found the fuel pipe and diff clearance to the boot floor was the problem in my older R400 build, so I went for a more radical solution by removing a non-structural portion of the diff cover:

A bit of fiddling around with cardboard templates and some careful measurement this weekend, but a successful creation of a new throttle linkage mount. I milled a few components to create the mount: The finished components and extra bolts to assemble: The components assembled with the Jenvey CLS1 linkage before fitting to the engine. The lower mounting bolt attaches to the Jenvey top manifold bolt between cylinders 1&2 (using a 40mm bolt instead of the standard 25mm one). The upper mounting bolt is 30mm long to replace the 20mm long fuel rail mounting bolt: The mounting faceplate has notches to clear the idle air bleed screws: Before the fuel rail is fitted, washers of the same thickness as the fuel rail mount are used to align the mount with the manifold bolt and tighten it, before removing the fuel rail part of the mount to fit the fuel rail: With the fuel rail fitted, all the mount bolts can be tightened and the clearance of the linkage checked and adjusted. The spherical joint on the cable quadrant in the centre can be seen clearing the fuel rail by about 5mm, as it is moved to full throttle: Next issue to tackle is the upper radiator hose getting in the way of the air filter backing plate: It was an easy fix by removing about 40mm from the hose length at the radiator end and tie wrapping the hose to various chassis points and other hoses and looms to prevent any vibration and chaffing: There is now enough clearance for the air filter backing plate: Another little issue that I wanted to rectify was the throttle pedal cable attachment. I’ve already had a snapped throttle cable due to the standard bodged saw cut and hole in the end of the pedal that stresses the cable end due to it not pivoting freely. I machined a pair of clamps to retain the nipple, but allow it to pivot. The clamp is bolted through the pedal shaft end that is cut off 8mm below the normal cable hole. The hole in the pedal shaft is drilled at 22.5 degrees from the car centreline, to match the angle that the throttle cable enters the pedal box: The cable can now pivot freely at the pedal end, although I need to fit a lower profile nut and bolt to avoid contact with the steering shaft at full throttle, than the standard M5 bolt I mocked up the clamp with:

Or Google “pounds sterling symbol” and copy and paste the £ into the message.

Another rebuild project is my garage laptop that is needed for Easimap, I need a reliable machine for the upcoming rolling road session. Last weekend I decided that the 10-year old cheap Asus laptop is no longer doing the job well with a screen that has a black failure area, a hard drive with increasing errors and general slow running. I found a refurbished Thinkpad T14 laptop with a 3-month warranty that at $525 (£305) is about 1/3 of the new price, having a 12-core CPU, 16GB of RAM and 512GB SSD and Windows 11 Pro. The laptop looks brand new and was likely a corporate lease return that sat somewhere during it’s corporate life with little use, It has enough RAM to run VirtualBox well, so I backed up Windows 11, installed Fedora 39 on it, then reinstalled Windows 11 in as a virtual machine. Messing around with Secure Boot and TPM took a couple of evenings to get the device drivers to load properly and I still have a weeks worth of evenings to do clean installs of all my car related software besides Easimap:

Thanks for the info John. I have kept the in-head injectors and rail, so have more space than you did on top of the Jenveys, but will have to tilt the top of the linkage to the outside of the car. My S3 chassis and other pipes and cables crowd the space too much under #3&4. On top of #3&4 may work, but on top of #1&2 have only a 180 degree bend in the throttle cable (it clears above the belt tensioner), compared with needing a 360 degree loop if I have the cable enter from the firewall end:

I thought it was going to be easier than expected to fit the throttle linkage to the throttle bodies. I mounted it underneath the body pair on #1&2 cylinders: With the top radiator hose tie wrapped against the side of the engine bay where it passes the link, there is just a few mm of clearance. Unfortunately in that position, there is no room for the air filter backing plate, as the hose can’t go lower by putting it under the diagonal brace in front of the oil tank. The next possible position is above the throttle body, but any straightforward mounting is not possible due to interference with the fuel rail. I think I have found a position just under the fuel rail if I angle the linkage just right, but I will need to fabricate a fairly complex bracket to hold it using either the fuel rail or manifold bolts (with increased length). As originally expected, it is one of the most awkward fettling tasks to tackle. Bits of aluminium to be cut and milled this weekend, hopefully I have enough pieces of scrap laying around to avoid going to Metal Supermarkets, as it is always a zoo there on Sat and closes early, too….

10 bar is rather a high pressure on the reservoir for bleeding, I normally use 1 bar. The technique sounds right, but the fluid flowing back into the reservoir is probably due to the high bleed pressure. The stream out the bleed nipple should be bubble free. If you are pressing the clutch during bleeding, I wouldn’t release it with the bleed nipple open, as air can be sucked in around the bleed nipple thread (same goes for when bleeding the brakes).

I think that many variants of the Duratec have a natural vibration in the 2000 to 3000RPM range, especially the variants without balancer shafts. Quite a lot of discussion on Mazda groups about it. My R400 engine had it around 2500RPM from new that induced a “buzz” through the chassis, especially on the overrun. If it is only apparent at lower RPMs, internal engine balance likely won’t have any effect on it.

On the subject of the harmonic balancer, for anyone using this thread for some hints on rebuilding their Duratec, I think there is a big issue if using an ARP bolt. ARP quote a torque of 190Nm for their bolt with molybdenum lubricant (https://tech.arp-bolts.com/instructions/251-2501.pdf), the lubricant adds about 25% clamping load over using just the corrosion inhibitor coated standard Ford bolt, or 238Nm of equivalent torque. When I tightened the standard Ford stretch bolt to 100Nm plus 90 degrees, it needed about 450Nm of torque. Using the ARP bolt could lead to a totally inadequate clamping force of only about 50% of the specification. I’m glad Raceline talked me out of using the ARP bolt, with their experience being that the standard bolt when tightened to spec with the friction washers is good for any of their engine builds up to the 280bhp version.