E85 / Flex Fuel Sensor - Rant

[BKC1]

I'm not impressed by the DSX ($300) and ZZP ($259) flex fuel kits for two reasons:

1. They're milking us for money, considering the OEM sensor (P/N 13577429) costs $75 and an E85 sensor pigtail starts at $8. Even if I include the cost to finish the harness and make a cool bracket via SendCutSend, a DIY kit should cost no more than $110.

2. They're incomplete designs. I forget who showed the first design at SEMA, but Katech or Lingenfelter and about 5 other companies are making flex fuel bypass modules that send a portion of your fuel through the sensor and a large diameter passageway so that the sensor doesn't bottleneck the low pressure fuel system. See the image below.

It's not just that the flex fuel sensor uses a 3/8" barb (~0.3" ID compared to 8AN ~0.56" ID), the sensing element is an additional restriction as shown below.

I made a spreadsheet of all the options, and I'm personally a big fan of the bypass system shown below. Not only is it the highest flowing and reasonably priced, it has a secondary outlet that can support port injection and/or a fuel pressure regulator.

Ultimately, I'm putting together a kit for myself, including building my own wiring harness and anodized aluminum bracket to mount the sensor bypass and a optional, boost-referenced Pro-series Aeromotive FPR (P/N 13145) FPR on the passenger side firewall. I've still gotta figure out some of those routing and mounting details to minimize the space required under the engine bay, but I'm working on it.

I'm not planning on building more than 1 of these (keep in mind I'm setting myself up for an aftermarket LT5 swapped ATS-V) but I figured I'd ask for feedback on the design and see if there's interest in making more of them. Even if it's not me, I hope somebody takes these notes and makes a better kit, because DSX and ZZP need competition.

My perspective is that parts that cost very little and significantly improve performance should not be milked for profit. If these parts were cheaper, more people would have them. Making the V-series competitive draws more people to the platform. People don't think "this guy had E85 and the other guy didn't so that's why the Cadillac won," they just know that Cadillacs are faster. That's why I don't like companies milking us for dollars on the real bang-for-the-buck stuff.

 

[MatthewAMEL]

This has been a discussion item on the C7Z and ZL1 for years. There is a reason GM never made a S/C engine with FlexFuel. Just the required fueling upgrades would add $5k to the price.

 

[BKC1]

This has been a discussion item on the C7Z and ZL1 for years. There is a reason GM never made a S/C engine with FlexFuel. Just the required fueling upgrades would add $5k to the price.

I've got that covered too. I'm prepping a similar thread talking about how nobody (not a single vendor) has the fueling system done right. They've all got one or two parts of a proper design done well, and for various reasons (either personal issues or mental hangups) they won't change.

Fuel is actually one if not of the hardest things to do correctly, and everybody has delusions of making it rich. The people that have been doing this a long time and doing it well don't sell their services for free or have no interest in forum banter.

The quick version of the fueling thread is:

• On the low end (800 RWHP on turbo, less on supercharger), it is sufficient to install a Walbro 450 (-274) or brushless pump and change out the PLV in the OEM bucket to increase pressure to 80-90 psi, which costs about $150 if you're handy. All companies but especially the likes of XDI are milking people for profit and leaving them in the dark about how they're making these "OEM+" units because it's making them tons of money. $100 profit per module x 50,000 modules per year is a good living, even split between a smorgasbord of vendors.
• On the high end, keeping a bucket around the pumps is critical to preventing fuel starvation, even with the cool ATS-V/CTS-V/BW tank designs, so in multi-pump setups only DW and Katech are on the right track. But both companies' designs are limited to DW pumps (which suck) and both won't consider improving their designs to support brushless. Aeromotive keeps saying their baffle system won't work on the Corvette, Camaro, and ATS/CTS and they won't sell it separately. Fore is compatible with Walbro but won't even consider a baffle or bucket. I'm working on the baffle part.
  • Most of these manufacturers are also committing a major error at the design stage that customers can't reverse. It's common practice to run one or two sizes smaller return line than your feed line but that's a big mistake. Watch Steve Morris' videos if you want to see how that plays out--on a super high flow fueling system, the regulator can't dump enough fuel back into the tank at idle because the small return piping won't allow it, and under load the pressure at the rail drops like a rock (now that a lot of fuel is being consumed instead of being sent back).
• One solid, open-source 3D printed bucket insert for GM and Ford fuel modules with instructions would destroy the aftermarket fueling industry, and in so doing massively improve the lives (and wallets) of car enthusiasts around the globe. Unfortunately, there are few guys that want to put in the hard work for the credit alone.
• Nobody read the pivotal article by DSX on tuning the fuel pump controller and none of the companies that make multiple pumps have the work ethic to provide a controller that'll handle the 2nd and 3rd pumps that they're selling. The fuel pump controller people are charging $600-1500 for a $100 part because again, they're trying to strike it rich.
  • I should mention that the head guy at DSX is a good guy, but he's overwhelmed with work and needs a solid electrical engineer (or two or three) to help him continue development of the special controller only offered on the C7 Corvette auxiliary pump. Without help I don't know if he'll ever have a standalone unit with adapter harnesses for sale. Any EEs out there with a suitable background and an interest should reach out to see if he's still hiring.
  • Bottom line is that the OEM controller is rated up to 22A so you can't use it to run multiple pumps. Unless you just want to run all the pumps as fast as they can go (i.e. bypass the OEM controller), you need a supplementary controller and knowledge on how to make it play nice.
• Everybody that sells a plumbing kit is marking up their hoses and fittings by an ungodly amount, and keeping people in the dark on the proper hose liners to use on fuel (not CPE, not virgin PTFE, you need carbon- impregnated PTFE to prevent pinholing and fires) because they'd make less money.
• Overall, somebody needs to put together a complete package, which includes a baffled multi-pump bucket insert with 12AN feed and return, a cheap controller with sensors and with universal wiring harnesses, an integrated mount for a fuel filter / E85 sensor / bypass module / FPR that supports direct and port injection, and solid guidance on which hoses to buy and build to connect it together.

Right now, doing a complete, future-proofed system costs $3-4k, and, judging from my experience and my engineering friends' experience, about 2- years of time learning. It should cost $1-1.5k, plug and play with no learning, and you should be able to incrementally improve parts of the system as your budget and build requires. So the starting cost for most people should be $200-500 for 93 octane and $500-800 for E85, depending on whether you go OEM+ single pump or multi-pump from the start.

 

[A Blackwing]

I was under the impression to run E85 on top of the $5k or so for fuel system upgrade, the cam would also have to be replaced with one that allows more fuel in as well.

Seems like a major investment to be able to run with a X3M thats running a $500 piggy back, $200 downpipe and fuel blend only.

This is before even factoring in driveline upgrades like clutch, one piece driveshaft etc.

 

[sleepys4]

I'm here for this! Was actually looking into fabracating a intake fuel pump for my car this week. Trying to take care of the low side dips before I get to the injectors. Thank you for what you are doing for this platform and others. If I can be of any assistance please let me know.

Jordan

 

[BKC1]

I'm here for this! Was actually looking into fabracating a intake fuel pump for my car this week. Trying to take care of the low side dips before I get to the injectors. Thank you for what you are doing for this platform and others. If I can be of any assistance please let me know.

Jordan

If somebody has a 3D scanner or a spare bucket (even for a base vehicle--I just need the dimensions), where I work we have a ton of 3D printer wielding, engineering nutjobs (in the best sense of the word) that are looking for an excuse to make something new. My focus is on the CTS-V (all three generations) plus the ATS-V, but if that goes well and there's interest I'll buy up some CT4/CT5 buckets and print designs for those.

If somebody wants to measure stuff, I'd like you to look for and propose a location under the cowl or adjacent to the shock towers where we can place a bracket for the E85 sensor/bypass/FPR. Don't bother putting anything between the shock tower and the engine--you'll need that space for other equipment (e.g. supplemental reservoirs, catch cans, etc). To my knowledge, on the ATS-V and CT4-V we should be able to leverage the same firewall brace bolt. However the CT4-V is more space-constrained due to the location of the coolant reservoir. It's probable that the same bracket will work on both cars, but you'll have to remove the cowling on the CT4-V to install it.

 

[sleepys4]

I will look into specific spots on the CT5 today, and see If I can get a bucket.