Fueling Requirements Question

[MkngStffAwesome]

Below suggests is can run 4.3PSI (30kpa) on the stock fueling any more and i'll need to upgrade.. which I could do but right now i want to get it legal and running.

My question is that 4.3 going to be the max i can run across the entire rev range OR can i run way more boost lower in the rev range cos in theory i need 1/2 the fueling at 1/2 the RPM ?

 

[cmoalem]

I would stick to the stock injectors and monitor AFR and injector duty cycles for now. (needs to be delivered by your logging/tuning software!)

If AFR does not get fat as needed while maintaining less than 80% injector duty cycle ... then I would step up in injector size one notch. (But this would need a complete retune even for the non boosted ops! But maybe you have a injector scaling factor somewhere which then needs to be set carefully...)

Oh ... up sizing injectors might mean fuel pump/pressure as well. And if you tune based on map then you might need to look into a extended range map sensor too (you will have a coarser resolution though) ...

Whole lot of worms on EFI

 

[MkngStffAwesome]

Sorry I should be more clear.. I want to run the stock injectors so i can retain the stock ECU and pump , reg and so on..
Having to replace replace all of this would be to costly at this stage.

I therefore have no way to monitor AFR at this point.

So it seems i have to keep below 4.3 PSI. but im not sure if that will be 4.3 across the entire rev range or that will be 4.3 at redline.. Because the E-turbo's boost is not directly tied to the Engines rpm maybe i could run twice the boost at 1/2 red line and id be just fine.

I could just try to maintain 4.3psi across all the rev range but that wont actually be easy because like we already know the e-turbo's boost is not related to the engines RPM.. and id obviously like more than 4.3psi. 4.3 at redline will be fine cos really i spend most of the time between 2.5- 4.5 k RPM and 7.5 PSI around those numbers would be great.

Thoughts ?

 

[WB projects]

I can't help you on the tunning side. But a wide band for the AFR is not that expensive and not that hard to install. I remember seeing one of you video that you remove you headers, don't remember exactly. But you just need to buy a wide band and weld a bong aside of your stock O2 sensor.
You need it to tune your car.
I have an AEM wide band and I have a "fire wire" connected to it so I can monitor the AFR with my computer for the tunner

 

[cmoalem]

tuning is imparative!
(otherwise you risk melting something due to lean at WOT!)

in WOT your stock ECU will not be in closed loop (stoich AFR 14.7 or lambda 1, within limitations of the stock narrowband capabilities) but in open loop and based on Volumetric Efficiency model (if your ECU uses VE models) trying to hit a much fatter target (AFR 12-12.8).

Much more Air means your stock WOT (open loop) models (whatever the ECU is using) are severely out of whack!

Without widebands you are not going to be able to tune your car yourself. Dyno operators do have the necessary equipment (widebands with sniffer tubes inserted into your exhaust from the back, but BEST is to sense O2 upstream of the catalytic converters with a bung and screw on widebands). If you are not familiar with DIY street tuning and the tools (software, interfaces and sensors) needed I would strongly recommend liasing with a reputable tuner (shop, person) in proximity. (He needs direct hands on access to your car!) (yes, some can do "remote tuning" but that involves you to have the sensors, logging and flashing software and your ability to exchange log files, receive tune files, flash them onto your ECU yourself, iteratively!!!)

uhhmm ... did I say somewhere eboosting is NOT cheaper than a bolt on mechanical boost (charger, blower) KIT (which usually comes with a base tune and/or tuning support from the seller)?

 

[AlexLTDLX]

To answer your question, you're correct - the engine will use less fuel at lower rpm. Though I really don't like using boost pressure as a fueling metric - a positive displacement blower engine will need more fuel than a turbo engine, and a turbo engine will need more fuel than an electrically supercharged engine at the same boost levels. And the e-boosted engine will make the most power of the three at the same psi too.

That said, you have a couple of easy options - you could run an old school FMU (fuel management unit) if your fuel system is a return-style system. We used to use these on mid/late 80's mustangs when they couldn't modify the factory tune. You could get them in different ratios - basically they were boost-referenced fuel pressure regulators, but with a rising rate - for example a 5:1 FMU would raise the fuel pressure 5 psi per pound of boost. You can still get them:

Vortech 6Z110-130: 12 1 FMU with 1/4 Barb Fittings - JEGS

Get the Best Performance with Vortech 12 1 FMU with 1/4 Barb Fittings 6Z110-130 parts at JEGS. Shop Now at the Guaranteed Lowest Price!

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Another, and in my opinion better, option is to run meth injection. Methanol is a fuel (obviously), plus it'll cool the intake charge, give you more octane for a much bigger tuning window and it's an oxygenated fuel - all wins. Plus, if you inject it pre-compressor it makes the compressor more efficient. My next video will be about this.