Exocet w/K24A2 Build Thread - SoCal

[cooltech]

lol, well, we already had the rolling skateboard assembled with the K24 in place. All that you see here is lifting the exoskeleton and placing it on the chassis. Everything lined up perfectly so, yes, that was easy!!

[cooltech]

OK, one of our top priorities after getting the Exocet frame was to determine what our options were for a fuel cell. This Exocet will be a full time race car and the OEM Miata tank tacked onto the back-end of a car that likely stops quicker than anything else in its racing class just didn't seem like a good idea. After a fairly exhaustive search we ordered some fuel cell "guts" (bladder, surge tank, fuel pump, sending unit, etc and we'll build the enclosure ourselves. It's about a 2-3 week lead time to receive so I think when we're not racing will shift our focus to the wiring and the brake lines... More soon.

[cooltech]

Been awhile since we posted and each of the past two weekends, we've made some reasonable progress on the Exocet build.

First up was making some modifications to fit the hood.  We wanted the back edge of the hood to overlap the bar near the dashboard as much as possible.  So, before mounting the radiator we focused on just getting the hood as far back as possible and down and around the highest point of the K24.

[cooltech]

We then focused on the hood latches.  We positioned the AeroLatches at 90-degrees to eliminate any interference with one of the cross-tubes.  We have not yet set final height of the hood - but you can see that we prefer to keep the gap from the top bar uniform from front to back.

[cooltech]

Then it was time to move on to mounting the seats.  The primary driver is Ryan at 6'-0" but we wanted to be able to move the seat up or back without a lot of effort.  We ended up adding the 1.5" (.125 wall) square tube at the front of the seat.  This accomplished two things for us.  First, the higher elevation allowed us to move the seat farther inward as it no longer interfered with the flange at the lower edge of the fixed tunnel.  Second, the taller front bar added an angle to the seat which we can either increase - or eliminate with the sidemount adjustment.

In the lower left front corner of the picture you can partially see one of our nut plates.  These nutplates are on the top side of each side rail.  Bolts go up from underneath the car - through the square tube & side bracket and into the nut plate.  With this technique, there is no need to hold the nut when tightening or loosening the seat bolts making it very easy to install/remove them.

[cooltech]

As our Exocet will be used exclusively for racing... and can stop faster than most cars in its class, we wanted to use a fuel cell instead of the comparatively vulnerable OEM Miata tank.  Further, as we will campaign the car in some endurance races where the rules allow for an initial fuel fill of OEM-spec volume (12.8 gallons) and then 10 gallons per stop there after, we needed a tank with a MINIMUM 12.8 gallon capacity.  Hence, we selected the 15-gallon ATL (SA115) tank but the stock ATL enclosure was too big (primarily to the large perimeter flange.  So we purchased the bladder with the surge tank and 100psi fuel pump already installed and opted to build our own enclosure.

We cut out the Exocet OEM tank mounts and then added (2) 1" x 1" bars.  To reduce height, we elected to recess the base perimeter angle-iron into the square tubes.... to gain another 1/8"  LOL!  In the pic you can see the enclosure tack-welded together.  Late in the evening we completed the shoe-box style cover and we will add two straps.  We elected to use 16-gauge steel for the enclosure - an big step-up from ATL's 20-gauge.

[cooltech]

Our frame arrived on March 9, 2017 and here it is December already... but the finish line is in sight! We have a dyno rented for Saturday morning where we hope to develop (optimize) the engine tune for our K24 using the Hondata ECU. From reading about others before us, withe the requisite (aftermarket) intake manifold and the tubular header, we are expecting to see 210-220 RWHP. The first objective is to make this "all out" tune safe for racing in hot weather. Time permitting, we may also embark on creating a second tune where we cap RWHP at ~175 in order to meet NASA ST3 Racing class specifications (10:1 weight to HP ratio).



We have done numerous customizations to this Honda-powered Exocet and I have been woefully deficient in documenting them in a build thread. Shame on me. However, I do plan on doing 2-4 distinct walk-around videos where I can point out various mods that we have done so other owners may consider to do these or even improve upon them. I'm quite proud of what we have achieved and we look forward to establishing some respectable lap times here on local Southern California tracks.



Here's a couple of recent pics.... always said that the windshield would be one of the final steps and here it is going into place (although still with protective covering.) Second pic is our switch box which is attached to a lateral tube we added to the chassis. NASA rules requires arms to be tethered in open cockpits so driver will have limited read capabilities. Switches were placed close to shifter but not in the way. Green light in switch panel is ignition on lamp. Red light was low oil pressure warning but as we have now incorporated alarms into the AIM dash, we re-purposed the red lamp to be the CEL.

[rc58]

Is your windshield bracket welded on or bolted on. If its bolted could you show how you did it. I havnt done a lot of thinking yet about how to do the windscreen would like to see what you all did.

[cooltech]

Hi rc58. They're all welded. The two (large) ones on the a-pillar were just stitch welded. The "center" support is actually offset toward the passenger side is also welded in. Finally, there are two more smaller tabs along the bottom - also welded. (Sorry)

[rc58]

Thats fine I figured as much since you were in raw metal. Purchased mine already coated. Beggars cant be choosers. It looks slick.

[cooltech]

Finally got in some initial track time.  Previously we had spent about 8 hours (across two different days) on the dyno to build two tune files for the K24.  The first tune was a straightforward and safe, 223HP tune.  The second was a tune built for the ST3 NASA classification where we must adhere to 10:1 weight to HP.  With driver, the car weighs in at 1800 lbs so we have a tune capped at 180 RWHP.  

The first track session went well (see pic below).  We have a small intermittent power Gremlin that we're chasing but think we have it solved.  More track time in a couple of weeks and first official race in March!  Giddy up!

[cooltech]

Added some lights for Endurance racing.  Will try to balance creating daylight in front of us and not roasting the back-side of fellow competitors!