As I think about it, 4psi with an intercooled, electrically driven supercharger is probably close to 6psi for an engine driven, non intercooled supercharger.

 

Re: Haltech - you're right to be concerned about wiring, but there's good news. The "Pro Plug-in" version I mentioned is literally plug-and-play, zero rewiring. It replaces your stock ECU directly using the factory harness and connectors. The older patch harness Haltechs required cutting/splicing, but the Pro Plug-in is designed specifically to avoid that. You could swap back to stock in 10 minutes.

That said, if you're happy at 4psi and the car feels great, honestly you might be fine staying there on the stock ECU. The F20C is pretty stout, and 4psi is conservative enough that you're probably not pushing any limits on 100 octane with proper AFR. Just keep an eye on those wideband numbers - if you ever see it creep past 13:1 under boost, shut it down immediately.

 

Very cool that you are getting this sorted out!

Curious what kind of timing numbers you are seeing now at WOT? Also what IATs you are seeing during a pull?

 

Cool project, do you have any pictures on the battery setup and spec on the cells?

 

The battery has a voltage of 84V and consists of 32 LTO cells in series. There is a charge only BMS and a 12V to 84V upconverter to continuously charge them from the alternator. The cells I am using are no-name (Generic) LTO prismatic cells. I could not find these cells any other way. There are brand name cells similar to these at 2.9 ahr and 10 ahr, but these fit in the trunk nicely and seem adequate. They are rated at 6 ahr with a C rating of 80, which means they can output 480 Amps. I need about 200 amps to get to 6 psi of boost at 8k rpm. These cells handle 200 amps easily - no heat, almost no voltage drop. They are durable and hard to kill, plus LTO is very safe. The only downside I can see is their weight - about 30 pounds for the complete battery and charger. At some point I may save some weight and replace this battery with the 2.9 Ahr cells. I expect the current battery has more capacity than I will use, the way I drive the car (street only). I figure this battery has about the same capacity as a 10lb bottle of nitrous, ie 100 hp for 100s, or 50 hp for 200 s. But of course it recharges itself when you drive, or it can be charged at home if needed.

 

The timing is stock, except I'm switching in a resistor in parallel with the ECT sensor to make the ecu think the car is running a little warm. I think that pulls 2 - 3 degrees (just when under boost) Hopefully is ok at 4psi. Do you agree? I don't plan to run 100 octane forever, just while I get it tuned. If I get to 6psi, do you think I'll need to pull more timing? Would probably have to do something with the IAT sensor. The intercooler is doing a pretty good job. I don't see much change in IAT while under boost, but I don't have an exact number yet. The IC is an off-the-shelf unit that is claimed to be good for 600 HP. I tried to measure the pressure drop across it but it was too low for me to measure accurately. Probably no more than 0.1 psi, if that.

 

I'm not sure what the stock timing is like for an f20c on the OEM computer. One person logged the obd port but was at high altitude so was still pulling a few inches of vacuum. Others on here have anecdotally reported as high as 35*. Id be interested to hear what you are seeing.

I'm running 28-30* in VTEC on my standalone for reference.

I think 2-3 degrees pulled is safe on 4psi with good 93. On 6 id probably try to pull 4*. Or are you stuck with 91 on pump?

 

I think I saw around 24 to 25* at 6k rpm, without boost. I need to check closer though.

 

Check at 6.5k and up. Gernby (a pretty respected former tuner on the site) always talked about how Honda kept the timing intentionally retarded up to 6* when VTEC kicked in to smooth the transition at 6k a bit.

Maybe you can set up a camera to watch the scanner while you do a pull so it's a little safer to do!

 

I'm in Florida, so we have 93 available.