battyone wrote:
Tezz wrote:
WOW sound great
on the fule side , you said the A/f was richer at 100% power , not for this project as you seam to have most things covered , but could you tune an engin to the slightly leaner A/F of mid range and just set the Max to 80 % and just use a bigger jet to get you overall power , so never run the pulsed system at 100%
Respect
Tezz
That was a suggestion from Loopy,quite a while ago.
Now many of us are using wideband O2 we are seeing what goes on during progression.
It would seem that afr during pulsing is leaner than that at wide open flow.Even without wideband it can be picked up on a static test,revs increase at first then flatten out as pulsoids max out.Not a massive problem though,I guess it's just not maximum efficiency.
Loopy's suggestion made sense,I believe it was a strategy that he used himself.
Another interesting thread/build...please no fires this time
I know someone using carbon runners and plenum..na. getting very favourable results.
Wideband is still a lagging indicator.
When flowing the kind of #s I'm looking for, leaving 20% on the table is really expensive and doesn't lend itself to system efficiency. You'd have to make things even bigger to hit the flow number, which negates a number of design principles regarding nitrous density.
I'm installing pressure sensors in the combustion chambers. You'll be able to SEE individual combustion events, and using the analysis software, determine how much fuel is being burned, how fast, and what the burn efficiency is.
With Motec or Pectel, we can time the phasing between the nitrous and fuel injection pulsoids. I'm not talking about varying duty cycle, I'm talking about varying the injection start time. We'll be able to tune this watching the burn pressure trace.
Getting a little bit off topic, I'll also be able to tune the cam timing in increments of 0.5 degrees while the engine is running. There can be a different cam position based on load (how much nitrous is being injected) and RPM. Normally on an N/A engine, the IVO and IVC are critical. On a nitrous engine, the EVO and EVC become more critical. With the BMW valve timing system, I can tune both in real time. (40 degrees of adjustment for intake, and 25 degrees of adjustment for exhaust) In real world terms, this means being able to move the intake centerline from 80 deg ATDC to 125 deg ATDC, and exhaust centerline from 115 deg BTDC to 90 deg BTDC.