I may have misinterpreted some of what you had said, but
Seems to infer that on the Exhaust stroke, if back pressure is raised, load and torque are increased. The next paragraph seems to infer the same;ScoobieWRX wrote: The pistons have to work a bit harder to push exhaust gasses out and that's where the torque comes in. If the engine works a bit harder you are seeing higher engine loads from lower rpms which translates into more torque.
That was the false assumption I meant, but admittedly I'm not completely sure what you mean by pistons working hard.ScoobieWRX wrote: 3" exhaust systems let the engine breathe more easily and aid exhaust gas escape so pistons don't have to work so hard to push exhaust gasses out. Great for bhp higher up the scale but not so good for torque. Because the pistons aren't working so hard you see much lower engine loads and in effect make less torque.
I wasn't referring to the active knock control of the JECS ECU, but
Seems to infer that the ECU needs to be remapped to add extra fuel given an increase in boost. It actually does this automatically and adjusts IDCs to match a given AFR for a given engine load (which is entirely determined by the MAF on pre 96 classics, or the MAP sensor on an ESL MAFless ECU).ScoobieWRX wrote:The issue is with the extra air being crammed into the cylinders. You've got to feed that air with fuel otherwise you're going to be running lean. If your ECU isn't mapped to feed enough extra fuel on boost you risk causing Det (knock).
Apologies if I did misinterpret what you wrote, but I couldn't see another meaning. I'm also not claiming any authority on this subject, I'd rather see it as debate.
Excellent reference btw, looks like Forced Induction Performance Tuning by Bell, which is pretty much the bible in this sector! I really must get back to work.
BR Mate
Andy
ScoobieWRX wrote:I realise your knowledge on these matters is far superior to the rest of us hence why you do what you do, so i'm always willing to be educated by someone that knows more.
However, I didn't suggest engine load is directly related to back pressure. Engine load is related to airflow and an indicator of how hard the engine's working. I don't think what i wrote suggessted otherwise. I forgot about the restrictor on Group N cars, my bad. Torque is affected by length and width of headers and exhaust. Have i got this wrong?
I didn't infur Torque and load are a direct result of back pressure. Granted peak engine load is directly related to torque, i don't think i've written anything that says different.
When the JECS ECU senses knock i know that it pulls timing however, i thought rightly or wrongly that upon sensing knock it doesn't actually add fuel until it goes into some sort of super limp mode. Equally i realise AFR in JECS is used to measure fuelling, it's the same in newage. I never mentioned IDC's, I'm confused?
We must read some of the same reference materials on exhausts from time to time. Others might find it useful too.
http://www.probe.lv/faili/downloads/pro ... steema.pdf
Thanks for pointing out my errors. It's always useful to know where you're gone wrong
