Project Update for October 10th, 2017: Much has happened to the M3 V8 CSL project over the past two months. Last time we covered the widebody flare design and construction, fuel cell and dry sump tank mounting and enclosures, Lexan windows, and the custom front bumper beam and 1M style cover.
This time we will show the installation of the carbon fiber hood, the delivery and installation of the HPR built 7.7L engine. To that we bolted a T56 Magnum transmission, twin disc McLeod clutch, and an SFI bellhousing. Onto the new motor we attached an ARE 4 stage dry sump oiling system, a hybrid set of LS7/CTS-V front accessory drives, and then Ryan started building a custom set of 1-7/8" long tube headers. We also re-did the seat / floor mounting (version 3), built a bunch of aluminum interior panels/floors, and mounted a giant rear wing with custom uprights and end plates.
The engine bay also received a lot of attention. A custom radiator and fans were ordered, brackets were made for a "rolled forward" installation, then custom radiator hoses built. An MSD Atomic manifold and 102mm throttle body were installed - backwards - and a custom dual airbox / cowl induction intake system was then built, with plenum sections extending behind the firewall and under the dash. Continue below to see the behind-the-scenes construction of all of this and more.
CARBON FIBER HOOD
The minimum weight we are allowed to run this car is fairly low in some series, and to get there we will have to eschew metal body panels for carbon fiber composites - where practical. Of course there are some exterior pieces that are very customized (flares) and it doesn't make sense to "go carbon" there just yet, but the hood, roof, and trunk panels are readily available so we went to AJ Hartman Aero for his motorsports level, lightweight, dry carbon hood to match the roof he supplied us earlier.
The first hood we received suffered some heavy shipping damage - but we purchased that one anyway, fixed it with some carbon fiber repair (
shown in the 330 build thread here), and used it on my BMW 330 which I race in NASA Time Trials. With a little bodywork and paint by our friends at Heritage it will look better - hoping to paint this car over the winter break (which is only about 2 weeks long, here in Texas!)
For this M3 CSL V8 build we wanted to start with an unblemished hood, and the second one arrived (in a crate) with no issues. It looked perfect and was weighed in at an astounding 9.5 pounds! We don't have an accurate weight on an M3 hood, but the original steel hood from my E46 330 was 44.5 pounds.
I can only "one hand" this hood because it is so light, with no glossy gel coat. Many aftermarket "carbon" hoods are made by: start with a fiberglass main structure, then add a thin carbon fiber overlay, then a thick glossy coat of resin on top to make it shiny. These end up being MUCH heavier.
The low weight on this "real" dry carbon hood also comes from the fact that about two thirds of the under hood structure is omitted. AJ builds this hood with a second layer of formed carbon fiber underneath to support the OEM style hinges and some of the side structure along the length, but leaves the middle and forward sections without the ribbing. The hood is made of several layers of carbon weave. Using the OEM style hood releases is not possible - because this is a racing part.
The fenders needed adjustment to fit the hood - we bought this rolling chassis with no front sheet metal or hood installed. The OEM "J-clips" were gone so Ryan installed proper nutserts into the upper frame mounting sections. The original fenders from my blue 2001 330 were then tweaked to fit and squared to the front end, all fitted around the carbon hood (top left). One of the old hood hinges was very bent so a new one was ordered and installed (top right).
After some time re-hanging the fenders (plus slotting some fender mounting holes) and tweaking the hinges, the hood and fenders fit nearly perfectly. We'll let the body shop do the final body gaps perfect, but I'm pretty happy with how it all squared up. Its gonna be a shame to cut a bunch of holes in this hood!
Since the twin OEM hood lathes and secondary catch aren't used with this hood we will need to install some AeroCatch hood latches - similar to how this pair shown above went onto my 330 using the same hood. These have functioned great for months without issue on that car, and we have used AeroCatches on many race car builds. Ryan will reinforce the radiator support on the M3 for the two hood pins, just like he did on my 330.
SEAT MOUNTING VERSION 3.0
This may seem excessive, to go back for a third time to modify the floor and seat mounts, but its pretty dang critical. We did this round of re-work
gratis, as we just were not happy with how the floor structure turned out after lowering the seat. And frankly the seat was too low for the customer. There might be a taller driver that takes laps in this car, but the owner is the primary driver, so we build around him.
Cutting out all of the OEM seat reinforcements, the two "risers" that travel from the door sill to the tunnel, weakened the floor structure enough to allow flexing of the floor if we pushed hard enough at the top of the seat. Not good enough. The problem was we were trying to make the seat low enough so his head can NEVER come close to the upper door bars, as this car may be street driven at some Optima events on the "road rally" portion without a helmet. It is ALWAYS tricky to make a safe roll cage for a street driven car. In a dedicated race car it is assumed the driver will always have a helmet on.
continued below