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Cayman The Destroyer!
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Discussion Starter #226
Well after an eternity and a half the beast started today. Unfortunately the turbo oil scavenging didn't work properly and it had to be shut down before any tuning could be done but I'll take it. Integration of the engine, transmission, suspension, ABS and data gathering is almost done. CFD aero analysis has pointed the way to an efficient package that produces meaningful DF with a good center of pressure and minimal drag. It was fun applying lessons learned and I can't wait to drive the car and feel the results on the very high speed turns at Willow Springs
 

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Cayman The Destroyer!
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2,571 Posts
Discussion Starter #228
Spent all day yesterday on the dyno looking for the throttle surge issue. Sticky waste gate and adjusting the cam transition set point fixed the issue but it was damn hard to diagnose. New fuel system worked perfectly. I never think of Porsche engines as torquey but this one is a torque monster. 635 lb/ft at the wheels! Moved our test day from Friday till next Thursday. Temps expected to be 65. Much better than Fridays high of 50. Infinite torque and no traction sounds like a bad idea!
 

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Cayman The Destroyer!
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Discussion Starter #229
Finally a test day at WSI last Thursday. All of the throttle issues that plagued the first test have been resolved. Boy did it feel strange to be driving a race car. Talk about sensory overload! Just the sounds alone are so different. The side exhaust, straight cut gear whine, turbo whistle, and blow off valve all sing a much different song! The super stiff chassis and cup car suspension communicate every bit the road feel. On low boost the engine almost feels normally asperated, no turbo lag and huge torque. Acceleration in 4-5-6 is unbelievable and to be truthful a bit scary! It always takes me some time to adjust to the limits of a race car and it will be a while before I'm dialed in.


Unfortunately an overheated gearbox cut the session short. Not sure if it's a cooling pump issue or if it need a bigger HX. Hopefully it will be easy to fix as the next race is at Buttonwillow Fri-Sun
 

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Cayman The Destroyer!
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Discussion Starter #230
I'm beginning to think I was born under a bad sign! While qualifying at Buttonwillow a rock hit the engine pulley and popped off the water pump belt! I only ran two laps but the engine overheated badly. The good news is the bottom end of the engine is OK but I ruined some valve guides and exhaust valves. Never a cheap repair for any of this!

Normally the entire bottom of the car is covered but we had the diffuser off to allow for easy inspection / adjustments.

While the engine is out I had Vision mount oil drain fittings at the back of each head and the bottom of the IMS housing. As time permits we can add the 4 stage Dailey pump and Peterson oil tank without having to remove the engine to have a real 18 quart dry sump system
 

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PCA Nat'l DE Instructor
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1,656 Posts
I'm curious...how do you know that a rock dislodged the belt? What evidence supports this conclusion? I'm not trying to be antagonistic, but if I were you I wouldn't want this to happen again so I'd want to be sure of the cause before declaring it an anomaly.

Sent from my XT1650 using Tapatalk
 

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Cayman The Destroyer!
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2,571 Posts
Discussion Starter #232
The dent on the pulley is the key indicator. Also this is the same engine and pulley drive that was fine for many street and race miles. Needless to say if I get another high engine temp alarm I'm going to shut it down immediately!
 

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PCA Nat'l DE Instructor
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1,656 Posts
The dent on the pulley is the key indicator. Also this is the same engine and pulley drive that was fine for many street and race miles. Needless to say if I get another high engine temp alarm I'm going to shut it down immediately!
Wow, sorry to hear it. Tthat's some really bad luck. High engine temperatures can have serious consequences, as you've discovered. Best of luck going forward.

Sent from my XT1650 using Tapatalk
 

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Cayman The Destroyer!
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Discussion Starter #234
I'm really excited that the car will be ready to go for next weekends POC race. Engine location fixed, new turbos, cool air for gearbox HX and a better intercooler scoop.

I love this pic shot by Martina Kwan at WSI. Some may call it dirt but I call it track patina!
 

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Cayman The Destroyer!
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2,571 Posts
Discussion Starter #236
?


Great shot.
? well we moved the engine to the back where a proper Porsche wants it! LOL A technician that no longer works at Vision installed the engine and gearbox in the car without 1" lowering spacers. The resulting axel angle caused CV joint issues. Vision stepped up and fixed it gratis. I'm very excited because lowering that much mass 1" will really improve the center of gravity!
 

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Needless to say if I get another high engine temp alarm I'm going to shut it down immediately!
Yeah... I had an issue like that cost our team an engine rebuild in the Mint-400 one year. Driver of Record/Car owner dragged the engine through a bush, ripped off the belt and his co-driver didn't say anything about the big yellow light pointed at his face that isn't normally on. Unfortunately that was before my stint so I didn't get to drive that day :(.
 

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Cayman The Destroyer!
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2,571 Posts
Discussion Starter #238
Yeah... I had an issue like that cost our team an engine rebuild in the Mint-400 one year. Driver of Record/Car owner dragged the engine through a bush, ripped off the belt and his co-driver didn't say anything about the big yellow light pointed at his face that isn't normally on. Unfortunately that was before my stint so I didn't get to drive that day :(.
That stinks! The diffuser is back on my car so hopefully the belt drive will be protected from foreign objects
 

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Cayman The Destroyer!
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Discussion Starter #239
Lots going on to move forward. Took care of heat issues by replacing turbos with properly sized and more efficient units from Garrett and increasing flow through the intercoolers. Results are more HP over the entire rev range and no more heat issues on track. So we found the missing 250 WHP and the car is now a rocket ship. Center radiator and new aero package are being installed. Dry sump system is being added as a hedge against much higher cornering forces. Scavenging at each corner of the heads, two sump, two turbos, four gallon tank and one pressure pump.

Other than tuning and addressing any issues found this will be the end of planned modifications. Time to work on the driver!!!
 

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Cayman The Destroyer!
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2,571 Posts
Discussion Starter #240
Good things come to those that wait. The DS pump and drive fit nicely. One additional benefit is we no longer need the deep sump so we gain ground clearance or can lower the engine and gearbox for a better CG
 

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