One question...
The IS38 variant you have actually has a ton of data uploaded by lots of people... Most of this data shows the stock HFPF being a bottleneck on pump gas OR the HFPF being upgraded on these cars.
I assume you specifically adjusted/tuned the injection window allowing you to maintain pressure on the stock pump? Adjusting for a HFPF that can't hold consistent pressure is different then installing one that wouldn't require you to do so (you still need to adjust, but it's not because of a limitation at that point). If you are hitting a ceiling, common sense says the HFPF needs to be upgraded. Did I miss something?
Also... Ed talking about a car that made 396/390 SAE on 93 oct with stock fuel pumps and Littco (Dan) saying a LPFP would be needed to address the breakup up top...
So I'll say it one more time...
Reliability, money aside, best supporting mods...
Upgrade your HFPF.
So, forget the IS38 variant I have and lets look at actual IS38 data because i had one of those for awhile too.
One thing to note is that there is nothing you can reallly do with the tuning to get more out of the HPFP. You can command additional rail pressure, but it's really a moot point because the pump can't physically deliver it. The injection window stuff can give you added capacity on the injector side, but again it doesn't change the limitations with the stock HPFP in place because they are physical limits due to the max volume/pressure the pump can flow. This is a hardware problem, there is no software solution.
I think we can both agree that the fuel demand on E30 is greater than pump gas, so safe to say i can skip the pump gas data, but here's a quick one.
This is a pump gas tune but i happened to have a touch of Ethanol in the tank at the time (E16). As you can see, fuel pressure is perfect. This tune made 367whp SAE, about 374whp std correction on pump, stock HPFP. I have at least 20 more logs that show exactly the same thing for IS38 on pump.
https://datazap.me/u/hoon/log-1524000987?log=0&data=4-6-30&zoom=52-128
For E30 data on the stock HPFP, i have tons also. I just grabbed a few at random, it's all the same shit. Some have more boost/timing than others but on E30 they all show the same fuel pressure.
Note the 15 degrees of ignition timing on this 1st one...this clearly isn't pump gas.
This first tune made 381whp on the hottest day of the year (likely a 400whp tune), and ran 9.7 60-130. This was a 120+ trap tune.
https://datazap.me/u/hoon/e30-v15?log=2&data=4-6-30&zoom=12-80
https://datazap.me/u/hoon/e30-v15?log=1&data=4-6&zoom=46-122&mark=101-99
https://datazap.me/u/hoon/log-1531442111?log=0&data=4-6&zoom=50-162
E35 on stock pump...we did find the limit here when pushing the turbo harder in cooler air. This is prior to HPFP, but HPFP was soon after this point:
https://datazap.me/u/hoon/log-1531865912?log=0&data=4-6-30&zoom=24-92
Whoa whoa whoa... what is this?
Talking about the same 396/390 SAE on 93 oct with stock fuel pump car above...
You have to keep in mind Dan is used to working on Euro cars with stock MPI so they tend to lean towards the low pressure side. I can tell you from experience that the LPFP (Walbro 450 @ 100% duty cycle w/ Torqbyte) does nothing on a DI car with the stock HPFP in place. The HPFP bottlenecks the LPFP and you gain nothing.
Ed is correct on that one, that car needed an HPFP...but that was an L450 car, IS38s are not making 400whp on crappy US 93 octane (on normal dynos). The airflow isn't there, so you need octane to do it via timing.
I would agree that a hybrid like an EQT or L450 requires an HPFP for pump gas or a mild E blend.
It's also important to understand that Cobb is the only mainstream tuning solution that can actually utilize the HPFP to potential. I would not recommend an HPFP for anyone else, the fuel pressure control is not there with Maestro, UM, etc and the injection window control isn't available to fully utilize the added HPFP capacity.
