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The major reason 911's accelerate better than Cayman's on track out is not the rear engine weight distribution but rather the superior real suspension. Is it possible to have the best of both worlds, mid engine and the 911 style multi link rear suspension? The answer is yes but it's not easy. After I blew the third gearbox in my Cayman turbo racecar we decided to put an Albins ST6 sequential gearbox in the car. The Albins is a longer box than the Porsche so we needed to stretch the wheel base a bit which also gave us room to use the rear suspension from a 996 Cup car. Vision Motorsports modified the rear frame and added mounting points that would allow the 996 rear suspension subframe to use stock mounting points. Vision had done something similar before and had fixtures and jigs to align the installation. Of course there was also a lot of body work to accommodate the stretch including wheel wells and flares to fit 13" wide wheels. To match the new rear suspension roll rate 996 RSR front uprights are used. This also made using the 996 cup brakes easy.
The end result is a 987 with a cup car suspension, paddle shifted sequential gearbox and 800 HP
Very cool! Looks like some very good well thought out work
Thanks, it's been a long road to get everything to work right and stay together. More time in the shop than on track. Looks like all of the issues have been sorted out. Time for the driver to get used to the final product.
One suspension issue we have had is getting the DSC shock controller to communicate with the Motec CAN. We have a new stand alone controller that only requires power and ground to work with the Tractive shocks It has it's own screen so no laptop need to program. Presets can be changed on the fly for comparison
Very awesome! I’ve followed your build over on P9 for awhile (same username for me) and that oil system is top notch.
Thanks! With the new Mezger 3.8L the pumps are all in the engine. The dry sump tank is the same as the old M97 engine. The coolers shown are for the engine and transmission.
Since my major competition comes from $600k GT3 R's and Cup cars with turbo engines I wanted to evaluate all of the systems in the car and one of the major disadvantages we found was the aero development the 911 based cars have. I was lucky to hook up with TotalSim while they where in LA for streets race and they agreed to laser scan my car for a very reasonable fee. (the measles pic) A CFD model was done to baseline the car. The results from the seat of the pants aero engineering actually weren't too bad yielding a 40/60 % down force split. Not only was the kit negating the lift we where making a fair amount of real DF
Aero is one of my passions and working with the experts at TotalSim we where able to increase the DF 300% with an increase in drag of only ~30% in the final simulations. It will be interesting to see how much ride height compression we get from the aero during high speed testing. We have some very high speed turns at our home track Willow Springs. Entry speeds will be around T1 90 mph, T2 110 mph, T8 150 mph T9 115 mph. I think I'll be changing my underwear often!
It's not a job it's an adventure! Finally got my little 3.8L on the dyno but not without some additional troubleshooting adventure. The car decided to shut down while it was being moved to the dyno. It turned out to be a bad igniter and a couple of bad coils. Parts where available and we also made a last minute switch from 100 to 130 cc injectors. So most of the day was shot and the Motec engineer couldn't stay too late. But he did get a rough tune done and we are very pleased with the power and torque curves. Final run was at 1.4 bar
09-01-2020, 12:52 AM
Cup Suspension On A Cayman
