Chasing high pressure fuel - a pump comparison and upgrade?

Here are the early beginnings of potentially upgrading the high pressure fuel pump for use with forced induction. At this point, all I can truely do is compare the various designs Toyota has utilized, and attempt to decipher how their features and dimensions may impact how much fuel they can pump. Is anyone aware of companies that can flow test these pumps? Hopefully, in the future, companies will publish specs.

Four pumps are pictured below, they cover most of the designs that Toyota is or has installed in their GDI engines. Listing the basics to start things off.

The top two are nearly identical. The stock Tacoma 2GRFKS is top left, a normally aspirated V6 with designs producing 278 to 311 HP. The Lexus V35AFTS is top right, a twin turbo V6 producing 409 hp. Both are used as a single high pressure pump in a returnless system. The 2GRFKS has a 9.5mm plunger, the V35AFTS has a XXmm diameter plunger. Bolt patterns are the same, but the flanges are slightly different. Bodies are stamped and lazer welded Stainless steel, weight 805 grams, do not appear serviceable. The bolt pattern and flange are rotated slightly, roughly 20 degrees, on the V35AFTS. So while it will bolt up, the connections will need adjustment.

The pump on the bottom left is from is from second gen Lexus 2URGSE, a normally aspirated V8, it produces 467hp. It is used in parallel with a second identical pump and is returnless. It has a 9.5mm plunger that will support the same stroke as the previous two pumps. The bolt pattern is 4mm narrower than previous pumps. The body is a brick sh#t house cast from steel, it's a full 200 grams heavier over the stamped units, topping out over 1000 grams. Most ports and passages are machined/drilled right into the solid mass. Might be serviceable, but not easily.

The forth pump is a first gen Lexus 2URGSE, a normally aspirated V8, it produced 416 hp. I'm including this unit simply because it's just a neat piece of kit... it's old school Toyota and can be completely dismantled with common tools. The plunger is 8mm, used with a second pump in parallel, fuel system of the return type, many differences over the previous pumps.

More to come.

 

Sub’d.

Is the thought that a fuel pressure pump = higher horse power?

 

We need a larger pump as the forced induction trucks are running out of fuel somewhere north of 400hp ... anyone have the exact number? The returnless system with PWM on the low pressure pump makes this a bit a complicated at present time.

 

Can someone please quickly start another oil change frequency debate thread, this stuff is way over my head.

Hat tip to OP up there in North Adam's (home of the "hair pin" turn!), this is some next level knowledge!

 

Lol, you are too kind. We'll need other folks above my pay grade... I'm mostly a hardware guy...

 

Can you mount the V35AFTS pump to a gr2-fks valve cover or does the flange prevent that?

 

It should mount up, but the depth could be a little different... so that needs to be measured. Also, having the same size plunger means it won't displace more anymore fuel per stroke than the stock pump.. all other internals being equal.

 

Would it be easier to add the extra fuel on the port side instead? Larger injectors and something like a boost a pump?

 

To a degree, yes, we can do that, I believe @mZiggy may have more info on that? The low pressure system, which feeds the high pressure system, along with the port injection, holds other solutions. Boosting the output of the low pressure system gives a boost to the high pressure pump, too, as they run in series. Optimally the DI should be the system we want running things under high loads, as the detonation resistance of the DI mixtures and timing are far superior to the port stuff. Toyota runs two high pressure pumps for appropriate supply and durability on performance applications... the drop to one pump is for cost cutting.

I was hopeful the single V35AFTS pump would have a larger plunger, but not the case.

 

Some low pressure system talk that lead to this thread. https://www.tacomaworld.com/threads/3rd-gen-fuel-filter-and-low-pressure-pump-system.687567/

 

Very interested in upgraded fueling for FI applications on the 2GRFKS. I hope this thread continues to evolve.

 

YotaWerx starts tune dev very very soon using the port injection fuel rails from @JamesT as an aftermarket upgrade, and we're very optimistic. In addition we already have proof of concept for the setup.

 

Any other upgrades? I'm more curious than anything... my Tacoma will never see boost. But I have a supercharged Mustang that also runs a returnless system. Really common to upgrade the wiring to the pump, driver (FPDM) and/or install a boost a pump or better factory or aftermarket pump.

I'm far from the expert on the matter but boosted returnless Mustangs have been around over 20 years so it's pretty much all been tried already. Cool to see it happening here too.

 

I mean, if someone puts something together I'm happy to explore options, but I'd also like to spend the majority of my time on options that will not entirely be one-off projects just due to level of interest unless I happen to have the additional spare time, if that makes sense.

The way the pumps get boosted matters though. See below for some context on this:

https://www.tacomaworld.com/threads...n-turbo-systems.566390/page-573#post-25331873

OVTune eventually went with an aftermarket pump + custom controller solution, but it hasn't worked out well on a larger scale due to parts availability; @JamesT has more info on that side of things since he's got one for his TT kit.

 

One offs are only good , from the business side, if they lead into another product or bring in customers that will buy other products. The bills always show up every month... and they need to be paid.

I just realized that simply because the exposed plunger on the three pumps is 6.5mm, doesn't equal the plunger bore being that diameter. The 8mm pump was easy to disassemble and check, so I'm assuming, which is soooo bad... We need specs, someone that can check flow, or we'll sacrifice some pumps!

 

You can successfully run a returnless system with boost to a point. It's not a hard number, but around 600hp it starts becoming a problem. When you have a returnless system you do what's called deadheading. This is when the fuel just rams into a wall and builds pressure and most importantly, heat. At higher pressures you get fuel pressure inconsistencies. That being said, you can drive a returnless system well above 600hp, and it has been done, but it's just not worth the effort. It's much easier to just run a return line and an aftermarket fuel pressure regulator. A return system also allows higher flow rates.

If you want big power, you need a static pressure pump (or PWM) and a return system. Return systems send heated fuel back to the tank, which increases evap and causes increased emissions, hence one of the reasons most cars are returnless now. That being said, return systems actually provide cooler fuel to the rails themselves due to the constant flow instead of heat inducing pressure.

@mZiggy, a return system can be added with my rails by the way, but honestly at our power levels it's not worth the effort. It would only help with the Port side anyway. With some clever modification it may be possible to use a return system as a method for adding in a bigger low pressure pump, but this would require the FPC to be tricked somehow. Not impossible, just not easy. An option to consider at least.

 

Ok, so I want to address a few things. Jowett and I have talked at length about some of these things as well as mZiggy, but I want to kind of lay everything out in one post. This is a multi-faceted problem.

Low Pressure Fuel Pump (LPFP): At 7-10 psi this thing is at it's limit. We found that we could run 7psi on the factory pump with base twin turbos, but at high loads for a long duration we put it at risk of failure. Anything over that and you further risk pump failure. To run the 10psi Powermax turbos we upgraded the pump to a DW300 Pulse Width Modulation pump, which requires it's own custom Fuel Pressure Controller (FPC) module. The factory FPC runs a 3 stage pump and is not compatible. Jowett and I have discussed the Lexus PWM pump and controller, but I don't believe this has been explored yet.

Port Injectors: We've been using the factory injectors to compensate on the Port Injection side, but at some point we know they run out of fuel. That point hasn't been shared with me, but there hasn't been any issues at 10psi. Upgrade options are limited to the Tundra 650cc DW injectors. Upgrading this without the low pressure pump upgrade though is kind of pointless since you'll never get enough from the pump to make use of them.

Port Rails: These are hugely imbalanced. They are fed from one end, so you end up having to over enrich the Port system to get the last few injectors rich enough to prevent knock. This causes the first few cylinders to be so rich they misfire. I'm currently releasing a set of rails that will completely eliminate this problem and is a gateway for further upgrades. The Pump and Injectors can be upgraded, but without the rails, you will always be fighting the imbalance, making tuning very very difficult. With the rails we can also lean things out a bit and give ourselves a little more fueling headspace without necessarily having to upgrade the former immediately.

High Pressure Fuel Pump (HPFP): This is already close to it's limit. Lexus (Toyota) added a second pump to it's V35 just because of this. Like Jowett said, the Direct Injection system is ideal for high loads since it cools the cylinders. Think of it like Power Enrichment. You add extra fuel specifically at high load/speeds to prevent detonation from increased temps. For boost, this system is very important.

Direct Injectors: Simply trying to feed extra fuel with the factory HPFP alone will require an upgrade to the Direct Injectors. The only option I'm aware of is the Lexus V35 Direct Injectors. They do not advertise the size, but they are much bigger. Even with these though, you'll run out of fuel with the factory HPFP pretty quickly. Mat tried to increase fueling over 7psi at first using Direct Injection, so we upgraded the injectors, but still hit the pumps limit. This led to trying to compensate with Port Injection.


To sum things up, at low boost it's HUGELY beneficial to upgrade the Port Fuel Rails to get a safe consistent fuel flow. This will allow tuners to compensate the additional fueling demand with the Port Injection system safely. After that you'll be limited by the Low Pressure Pump before all else. Ideally we want to upgrade the Direct Injection system as well, but that's not readily solved yet.

In a normal engine you would simply add a bigger pump and go to bigger injectors to match. Easy day. In these engines, you have two pumps, and two sets of injectors. And to make things worse, they work in tandem. This truck switches between Port only, Direct only, and both combined in order to achieve equilibrium. So when you start adding boost, you can only go so far with just one side. At low boost we can get away with it, but to go higher, we need to upgrade both sides. Using Port injection is a bandaid. It works, but it's not as good at high loads as the Direct Injection would be.

Right now I'm running 10psi with a PWM Low Pressure Pump and custom FPC, Lexus Direct Injectors, Upgraded Fuel Rails, and Factory Port Injectors. I'll probably run out of fuel at my Port injectors before too long and I'm already at my HPFP's limit. Still exploring through tuning just how high we can go with this, but the rails are proving to be key to using Port Fueling to compensate.

So I'm thinking that as you increase boost levels, you should upgrade in this order: Port Fuel Rails -> Low Pressure Fuel Pump -> Port Injectors -> High Pressure Fuel Pump -> Direct Injectors.

If we can sort out the HPFP upgrade, then that would definitely be bumped up on the list as theoretically we can compensate a lot of the fueling needs with that alone.

 

Extremely well put sir.

 

The 2URGSE pump was sacrificed since it was damaged and thus purchased cheaply. The plunger bore is a much larger 9.5mm diameter (DLC coated, too). More digging on these pumps is required. The 6.5mm diameter of the push rod portion of the plunger doesn't allow us to know the diameter of the working part of the plunger. Making corrections in first post.