Surge tank setup?

[Iron Indian]

Hello, I have a 2019 S550 that currently has a Fore triple pump setup. I know most people go with this setup however it has many short comings I do not like. With that said, I want to get rid of it completely.

I’m feeding a 1000+ hp setup so the Radium bucket setup won’t work. Deatschwerks has a triple pump bucket setup I could use. However, x3 285 pumps at WOT sucks a lot of fuel and I honestly don’t think the bucket will stay full during a WOT pass with out a Venturi.

My last thought is reinstall an OEM fully functioning bucket setup, and have it feed a surge tank with triple pumps. I know the S550 has a saddled tank design and pulls fuel from both sides of the tank. However I don’t know if this could work as a feeder or not.

I’ve don’t surge tanks on other cars before, I want to make sure I’m not missing something before diving in. I bought the car with the Fore setup already installed. I’ve never seen what an OEM setup looks like.

hopefully someone can offer insight on this? Regardless, keeping the Fore isn’t an option for me. Not point in running a surge tank with bucketless junk. Defeats what I’m trying to do.

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[mejohn50]

If anyone knows what the OEM fuel pump module and other fuel system components can do, it's @engineermike.

I have contemplated a surge tank setup before, and it's still something that pops into my head frequently. In my opinion, it could be the least worst way to feed high power setups on this platform...assuming it's setup well and ignoring the hassle of finding a (safe) place to put it and plumbing it all up.

Mike can likely share more data on this, but you still may have some issues with the OEM GT in-tank pump module. It may not flow enough, even at basically open flow, to keep a surge tank full. It's also possible that it flows too much fuel for the venturis to keep up with and keep the bucket full since they can only move so much liquid.

 

[engineermike]

I've spent more time studying and testing these designs than I care to admit.

@Iron Indian your reasoning and concerns are dead-on. The bucket serves a purpose, so anything that gets rid of it is compromising the system. Yet, keeping the bucket full is a challenge as well. Both Radium and DW buckets are worse than stock in this regard, because they don't use a venturi pump to fill the bucket from the driver's side. The short answer is to refer you to KPM. They focus on and prioritize bucket-filling. However, with the KPM system they are a bit spendy, lack a proper filter, could be a challenge to wire and tune if you want the PWM control to work with the PCM, and lose factory diagnostics (if one pump fails, you won't know about it until it until you go WOT).

There are some basic concepts to understand. The factory bucket uses not one, but two venturi "pumps" to fill the bucket. One pulls from the passenger's side of the saddle while the other pulls from the driver's side. The bucket itself contains about 1/2 liter of fuel. The driveshaft hump is higher than you'd think. I'm guesstimating that you'd need around 2/3 of a tank to overflow to the passenger's saddle. The passenger's side venturi is always pulling fuel from the passenger's saddle into the driver's saddle. Therefore, there is a strong chance that when the fuel is lower than some amount (possibly 1/2 tank or so), the passenger's saddle is actually dry. This is of no real concern except that you're now only getting one venturi pump filling the bucket instead of two.

When designing a fuel system, a couple of critical decision needs to be made. Do you want full bucket filling rate for indefinite WOT, and do you want full bucket filling rate for indefinite WOT while pulling only from the passenger's side (such as the case as a hard left hand turn at sustained WOT). The stock Gen3 and KPM appear to be the only ones that are capable of handling the latter case, as the passenger's side venturi alone can supply the stock engine's (Gen3) max demand on gasoline. The KPM appears to be designed to handle max filling case, passenger's side only, for even FI on E85. Interestingly, Gen2 and GT500 appear to not be designed to handle this case. In fact, the GT500 bucket driver's side venturi pump is identical to the Gen3, and it doesn't appear to even be able to keep the bucket full at WOT indefinitely in stock form.

I'm using a stock GT500 fuel module, which has enough pump capacity to handle 1000++ hp, but I don't think the same can be said about the bucket-filling rate. In fact, I tested this and found it to only fill the bucket at about 220 lph (driver's side venturi only) while the pumps can deliver 450-500 lph to the engine. After playing with venturi nozzle and throat sizing and pressure, I was able to get 380 lph out of the driver's side venturi pump. Passenger's side I was only able to improve it from 150 lph to about 200. At my power level I'm sending about 450-460 lph to the engine so it can't sustain indefinitely, but I do have the 1/2 liter in the bucket. Assuming the 380 lph bucket fill rate, the 1/2 liter of capacity in the bucket can get me over 20 seconds at WOT before the bucket goes empty. This assumes no help from the mushroom valve. I can't say I'm super satisfied with this solution, but the logic behind it seems to pass muster at Ford for Gen2 and GT500.

 

[Iron Indian]

I've spent more time studying and testing these designs than I care to admit.

@Iron Indian your reasoning and concerns are dead-on. The bucket serves a purpose, so anything that gets rid of it is compromising the system. Yet, keeping the bucket full is a challenge as well. Both Radium and DW buckets are worse than stock in this regard, because they don't use a venturi pump to fill the bucket from the driver's side. The short answer is to refer you to KPM. They focus on and prioritize bucket-filling. However, with the KPM system they are a bit spendy, lack a proper filter, could be a challenge to wire and tune if you want the PWM control to work with the PCM, and lose factory diagnostics (if one pump fails, you won't know about it until it until you go WOT).

There are some basic concepts to understand. The factory bucket uses not one, but two venturi "pumps" to fill the bucket. One pulls from the passenger's side of the saddle while the other pulls from the driver's side. The bucket itself contains about 1/2 liter of fuel. The driveshaft hump is higher than you'd think. I'm guesstimating that you'd need around 2/3 of a tank to overflow to the passenger's saddle. The passenger's side venturi is always pulling fuel from the passenger's saddle into the driver's saddle. Therefore, there is a strong chance that when the fuel is lower than some amount (possibly 1/2 tank or so), the passenger's saddle is actually dry. This is of no real concern except that you're now only getting one venturi pump filling the bucket instead of two.

When designing a fuel system, a couple of critical decision needs to be made. Do you want full bucket filling rate for indefinite WOT, and do you want full bucket filling rate for indefinite WOT while pulling only from the passenger's side (such as the case as a hard left hand turn at sustained WOT). The stock Gen3 and KPM appear to be the only ones that are capable of handling the latter case, as the passenger's side venturi alone can supply the stock engine's (Gen3) max demand on gasoline. The KPM appears to be designed to handle max filling case, passenger's side only, for even FI on E85. Interestingly, Gen2 and GT500 appear to not be designed to handle this case. In fact, the GT500 bucket driver's side venturi pump is identical to the Gen3, and it doesn't appear to even be able to keep the bucket full at WOT indefinitely in stock form.

I'm using a stock GT500 fuel module, which has enough pump capacity to handle 1000++ hp, but I don't think the same can be said about the bucket-filling rate. In fact, I tested this and found it to only fill the bucket at about 220 lph (driver's side venturi only) while the pumps can deliver 450-500 lph to the engine. After playing with venturi nozzle and throat sizing and pressure, I was able to get 380 lph out of the driver's side venturi pump. Passenger's side I was only able to improve it from 150 lph to about 200. At my power level I'm sending about 450-460 lph to the engine so it can't sustain indefinitely, but I do have the 1/2 liter in the bucket. Assuming the 380 lph bucket fill rate, the 1/2 liter of capacity in the bucket can get me over 20 seconds at WOT before the bucket goes empty. This assumes no help from the mushroom valve. I can't say I'm super satisfied with this solution, but the logic behind it seems to pass muster at Ford for Gen2 and GT500.

Thanks for your insight..

What I really would like to know is if a stock fuel module or a stock fuel module with an upgraded pump would be sufficient enough to work with a surge tank as a feeder. If so, this to me would be the best solution for me. Like I said, I’ve done surge tank setups before and they work really well and literally can support damn near anything, however (in my opinion) for it to work as intended, you really need to have all the stock venturis work as they should in the main tank. No point of a surge tank if the main tank catches air because of a bucketless or hacked module.

 

[engineermike]

@Iron Indian is the intent for the surge tank fill rate to match the max engine consumption?

 

[Iron Indian]

@Iron Indian is the intent for the surge tank fill rate to match the max engine consumption?

I plan on running a Radium MPFST surge tank setup. (https://www.radiumauto.com/MPFST-Multi-Pump-Fuel-Surge-Tank-P1565.aspx)
I’ll likely run it with x3 274 or 285 fuel pumps. I just need to make sure the feeder pumps keep the tank filled as intended. I need it to support at least 1500 rwhp for wiggle room.

 

[engineermike]

I plan on running a Radium MPFST surge tank setup. (https://www.radiumauto.com/MPFST-Multi-Pump-Fuel-Surge-Tank-P1565.aspx)
I’ll likely run it with x3 274 or 285 fuel pumps. I just need to make sure the feeder pumps keep the tank filled as intended. I need it to support at least 1500 rwhp for wiggle room.

So you need 700 lph of fuel.

That means you need 700 lph pumped out of the surge tank.
You need 700 lph pumped out of the fuel tank into the surge tank.
And you need 700 lph pumped out of the saddle tank into the bucket.

The problem is that a stock fuel bucket, even with an upgraded fuel pump, is not going to flow 700 lph into the surge tank. And the venturi system will not flow 700 lph to keep the bucket full. You're left with all the same problems you had even without the surge tank.

The only way I see this working is with the KPM2200 ($5000). That said, I'm actually not even seeing where the surge tank even buys you anything in terms of performance. You still have to supply 700 lph of fuel to it so you might as well go straight to the engine if you have the capability to push that much fuel out of the saddle tank.

 

[engineermike]

I was able to hit 700 lph bucket filling rate today using both (ds and ps) venturi pumps and a pressure of 80 psi.

 

[wingnutt]

I plan on running a Radium MPFST surge tank setup. (https://www.radiumauto.com/MPFST-Multi-Pump-Fuel-Surge-Tank-P1565.aspx)
I’ll likely run it with x3 274 or 285 fuel pumps. I just need to make sure the feeder pumps keep the tank filled as intended. I need it to support at least 1500 rwhp for wiggle room.

as Mike has said…I believe KPM was designed for just such a scenario, but add a couple of his improvements for sure and this is just the 1500 kit

 

[Iron Indian]

I was able to hit 700 lph bucket filling rate today using both (ds and ps) venturi pumps and a pressure of 80 psi.

how do I do this? Wish I could just buy something off the shelf that could do this

 

[Iron Indian]

as Mike has said…I believe KPM was designed for just such a scenario, but add a couple of his improvements for sure and this is just the 1500 kit

From my understanding all of KPM numbers are based on regular fuel, not E85. I make over a 1,000 now on E85 and with my new motor I’ll be going over that. I figure I need at least 1,500 capable on E85 to support what I’m trying to do.

 

[engineermike]

how do I do this? Wish I could just buy something off the shelf that could do this

This was done using a gen3 bucket, drilled venturi throats, drilled venturi nozzles, trimmed degassing stacks, pressure increased to 80 psi, and delivery from both venturis instead of one. But this is just the bucket filling rate. You’d then have to have pumps that could supply 700 lph at the 80 psi, which would be like a pair of dw400’s boosted to 20 volts. But again, if the fuel module can supply 700 lph at 80 psi then there would be no need for a surge tank.

 

[engineermike]

From my understanding all of KPM numbers are based on regular fuel, not E85. I make over a 1,000 now on E85 and with my new motor I’ll be going over that. I figure I need at least 1,500 capable on E85 to support what I’m trying to do.

That’s why I converted your hp desired into lph and mentioned the kpm2200 version earlier.

 

[wingnutt]

From my understanding all of KPM numbers are based on regular fuel, not E85. I make over a 1,000 now on E85 and with my new motor I’ll be going over that. I figure I need at least 1,500 capable on E85 to support what I’m trying to do.

understood, and like @engineermike mentions above, they have systems up to 2700…the link I posted was more for what they do

https://kpmfuelsystems.com/?store_s..._brand=42&search_model=78&search_category=148

 

[Iron Indian]

understood, and like @engineermike mentions above, they have systems up to 2700…the link I posted was more for what they do

https://kpmfuelsystems.com/?store_s..._brand=42&search_model=78&search_category=148

any heavy hitters running this setup? I’ve researched and I can’t really high HP guys who run this. Most run the junk I have now.

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