Twin Turbo 928 fixed and back out there terrorizing the streets!
#1367
Nordschleife Master
Thread Starter
;-)
This has about the same AFR to lambda mapping as regular 93 unleaded pump gas, whereas E85 has a very different mapping. So E85 is not useful in tuning a pump gas car. Plus feeding this engine with enough E85 using a reprogrammed LH would be a bit of a challenge.
In contrast, we can tune the car with this race gas safely first, and then step down the octane level by blending in pump gas and pull boost and/or timing. Alternatively, we can start very conservatively with pump gas and then blend in the race gas while adding boost and/or timing. Fixing the AFR to the predicted ultimate richness across all these tests regardless of the octane level, say 12.0 AFR, is going to be close enough for government work in the first pass.
This has about the same AFR to lambda mapping as regular 93 unleaded pump gas, whereas E85 has a very different mapping. So E85 is not useful in tuning a pump gas car. Plus feeding this engine with enough E85 using a reprogrammed LH would be a bit of a challenge.
In contrast, we can tune the car with this race gas safely first, and then step down the octane level by blending in pump gas and pull boost and/or timing. Alternatively, we can start very conservatively with pump gas and then blend in the race gas while adding boost and/or timing. Fixing the AFR to the predicted ultimate richness across all these tests regardless of the octane level, say 12.0 AFR, is going to be close enough for government work in the first pass.
#1368
Nordschleife Master
Thread Starter
Wiring of the solenoid valves under the boost box
The little control system's actuators that allow for closing of the wastegate when the control logic so desires:
#1370
Nordschleife Master
Thread Starter
In my opinion, yes. Opinions vary, of course. Although it's rarely done in a formal optimization way, tuning is just a simultaneous estimation-optimization problem. Race gas makes the knock constraint less binding and therefore allows the functions to be estimated more easily. What this means in practice is that it's easier to figure out the torque produced as a function of ignition timing for given boost setting and rpm, because you can sweep a larger area of alternative ignition timing settings without having to worry about the knock. Now, I'm not a professional so someone more experienced may think that this is wrong/irrelevant/waste of time.
#1371
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In my opinion, yes. Opinions vary, of course. Although it's rarely done in a formal optimization way, tuning is just a simultaneous estimation-optimization problem. Race gas makes the knock constraint less binding and therefore allows the functions to be estimated more easily. What this means in practice is that it's easier to figure out the torque produced as a function of ignition timing for given boost setting and rpm, because you can sweep a larger area of alternative ignition timing settings without having to worry about the knock. Now, I'm not a professional so someone more experienced may think that this is wrong/irrelevant/waste of time.
Åke
#1372
Nordschleife Master
Thread Starter
Custom filter element ready
"I'm saying it's going to look pretty wicked. The filtration area is 17.5"X12". It's absolutely massive."
Last edited by ptuomov; 12-04-2016 at 12:47 PM.
#1374
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How much mass does all this add to the front end? (Thinking weight balance and likely the need for Big Big brakes on the front. Might need more spring too.)
#1375
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Enough to keep the front wheels on the ground when he launches, mostly.
#1376
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#1377
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Originally Posted by ptuomov
While I'm having a rough month traveling, John's testing the fuel system. Everything seems to pressurize correctly, no smell, no leaks, and pressure holds well downstream of the check valve.
Personally, in November I've done two World Series games in Chicago, long weekend in Disney World, some private clubs in London, a week in Cape Town, and now Thanksgiving in St. John. This was supposed to be my vacation month, and I feel like I need a vacation when I get back from vacation! How do the Europeans do this every year with their seven week holidays???
Personally, in November I've done two World Series games in Chicago, long weekend in Disney World, some private clubs in London, a week in Cape Town, and now Thanksgiving in St. John. This was supposed to be my vacation month, and I feel like I need a vacation when I get back from vacation! How do the Europeans do this every year with their seven week holidays???
#1379
Nordschleife Master
Thread Starter
We've got to see where it lands. The earlier system added maybe 50-75 lbs to the front, this system should probably be pretty close to that. Then again, I'm about 40 lbs lighter myself compared to the previous iteration...