Originally Posted by Thumper SRT6
Yeah, it turns out his problems at WOT were due to the fact he had headers installed. When I read the thread, the headers were still being fabbed. I missed his post were he stated they got installed. He made a post in a different thread (the LET headers thread) stating he had no problems with the 192mm pulley UNTIL he installed the headers. Here is that post:
https://www.crossfireforum.org/forum...9&postcount=69
So that means we don't yet know what ratio will give us fuel problems at WOT WITHOUT headers. It could still be possible to combine the S/C pulley with an aftermarket crank pulley after all. Hopefully Code3 will do just that and post info.
As to the 192mm running the S/C at near max, someone posted that, but didn't show their calculation. They just stated a number. I wish more people on here would show their calculations, so that others could verify the numbers.
I'll try to actually measure my S/C pulley today, so we can be sure of the size. My calculations above are based on the size Brian stated. I don't think he's lying, he just never said were he got that info. And I haven't had the chance to do more research to verify.
I measured the stock crank pulley (which I have removed and replaced with LET's 185mm pulley) with a steel machinist's rule, my calipers weren't big enough so the numbers could be off a little, and the stock SC pulley when I had the belt off. My numbers were pretty close to post #10 in this thread.
To add more to this discussion, it's my understanding the limiting factor turns out not to be the maximum SC RPM, that's just the mechanical limitations of the SC, but it's the Bosch ECU.
When the ECU is in the open-loop mode (yer rippin' down the road) - once the MAP sensor signals the ECU with a 22-24PSI reading, (that's just about MAX boost of my 185mm pulley) the ECU then stops adjusting the fuel maps. Once this happens, and if MAP continues to rise, you will begin to run lean because the ECU will no longer try to add more fuel to keep up with the increasing air supply (A/F ratio). The lean A/F ratio will be detected by the O2 sensors, the ECU will signal a CEL and begin to pull timing. There's been talk of a MAP clamp so as not to signal the ECU of overboost, but I'm not sure how that would solve the issue of fuel map selection by the ECU.
I think this is what what was happening to AMGrasoul who was running the 192 pulley - he was just over boosting the MAP sensor and creating a lean condition, as the cylinders heated up he would pre-detonate, causing all kinds of issues...