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Originally Posted by serialk11r
Seems like this project is getting expensive :P
Sorry I forgot what radiator you're using, is it the stock Insight unit? Bigger radiator is definitely preferable to fans coming on or less grill block for sure.
If you're heat soaking and knocking already, that's not great,
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Yeah, stock Insight radiator. Some more thorough ducting as another member is doing on here could help with this.
I want to say that on my last 10 commutes, only on one did I measure and knock. It was 5 total knocks and they all happened at 1750-2250rpm at full throttle, where volumetric efficiency is highest - I believe I've seen as high as 107% there. I pulled a half degree of timing from the very top of the map and haven't yet seen any more, but I'm keeping an eye out for it as the weather warms.
Quote:
Originally Posted by serialk11r
I would give DIY EGR a shot. EGR has higher gamma and low oxygen which both help reduce knock compared to hot air. The stock cam timing should be near best compromise for EGR, combustion stability and pumping losses, external would EGR allows modified cam timing while retaining (or even increasing) EGR fraction.
You would need some way of not messing up the fuel trims since the Honda ECU doesn't use MAF. There has to be some kind of internal compensation built in, but without knowing how it works, it's hard to say if you can go mess with it and expect it to work. If it has a full fueling compensation table that can be learned for all closed-loop conditions, you don't need precise electronic EGR control.
A crude system to control EGR would be two valves in series: One that varies aperture in proportion to the throttle (to prevent misfires from too much EGR at high vacuum), and one that closes off near full throttle. This will produce decreasing EGR fraction with increasing throttle.
One passive method would be to attempt to meter a relatively constant fraction of EGR except at idle, which can be done with a "carburetor" like mechanism feeding exhaust ahead of the throttle plate. A signal from the idle control valve can shut off the EGR supply, and full throttle can also shut it off.
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The knock only happens at full throttle, where cylinder pressure is highest, and very slight reductions in timing advance and temperature seem to improve it a lot. I'm not getting any at even 95% peak MAP.
I'm not sure I have access to the original Honda maps. Hondata publishes some base maps which are supposedly "equivalent", but the ECU I'm using is for an entirely different engine.
As for tables, KPro has a different set of tables for every 10 degrees of intake cam advance, for both the low and high cams. This includes ignition timing, fuel, knock sensitivity, knock ignition limit, and knock retard.
There are full maps for lambda, and offset tables to modify lambda based on coolant temperature, at low and high load, on it low and high cams, plus a separate table for lambda when it crosses into the "WOT" region (which can be set).
Fueling can be modified by tables for intake temperature (low/high cam and load regions), cam angle, coolant temperature, battery voltage, and what gear you're in. Injector phase can also be modified by map region.
It supports flex fuel (with a sensor or fixed values) and has lots of compensation tables for ethanol percent.
Ignition timing can be modified by whether A/C is running, engine load region, air temperature, water temperature (multiple tables), battery voltage, as well as set dwell angle.
One can also have triggers, both inputs and engine conditions, which cause various events (if then, and/or) such as activating outputs or changing fueling or timing.
There is traction control, the ability to use secondary intake runners, nitrous support, electronic boost control, tip-in parameters, rate of change, but nothing natively for EGR. However, I bet I could set it up with if/then statements.
Quote:
Originally Posted by serialk11r
As far as fuel economy goes, retarding the intake cam by ~30 degrees will drop VE by something like 13%, and if you can get slightly higher EGR dilution, you might be able to get 20% drop in VE. Bringing MAP from 0.5atm to 0.6atm is probably worth something like 3-4% in fuel savings.
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General wisdom in the Honda community is to advance the intake cam to get fuel savings, but I didn't see any. My guess is it's largely due to my not having different ignition tables yet for the various cam advance positions.
I plan to work on that this weekend.