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Has anyone ever fitted dual 340lph fuel pumps in the stock thirdgen tank? I found a few threads mentioning it works with a 4th gen tank due to the larger opening, but not much regarding the thirdgen tank. I'm looking at getting two of these being my 525 hellcat pump turned out to be a chinese knock off.
https://www.summitracing.com/parts/aei-11540
I did some digging and it looks like the pump diameters are nearly the same so they SHOULD drop in. The Aeromotive pump is actually a hair smaller. I'll post my results.
Do you think a Walbro 450 will provide enough fuel? Racetronix sells dual pump kits but as you said, most are for 4th gens. However, there is room for both pumps in the 3rd gen tank. It might just be hard to get them in and have the pickup in the tank sump. I am assuming your dyno session uncovered a fuel starvation issue?
Do you think a Walbro 450 will provide enough fuel? Racetronix sells dual pump kits but as you said, most are for 4th gens. However, there is room for both pumps in the 3rd gen tank. It might just be hard to get them in and have the pickup in the tank sump. I am assuming your dyno session uncovered a fuel starvation issue?
I’m still using the 3/8 feed line so I’ll need a lot of flow at a higher pressure. A 450 will probably just make it, but I want some future headroom so if the 340’s will fit I should be good for a while. We got the car strapped down and on the first wot hit fuel pressure dropped from 70 down to the low 40’s at around 4200 rpm. We had this same problem a few years ago when I first put the lsa on. My tuner swapped my then AMAZON 400 pump for a genuine Walbro and the problem was solved. I checked the specs on the knockoff 525 in there now and it only flows around 380lph at the 70psi.
I pulled the sender on the dyno to make sure the pump to feed hose didn’t split and everything was good. I’m planning on upgrading the feed to a -8 eventually, but the rail steps down to a 3/8 again anyway, so I rather just run the smaller feed until I can upgrade the rail with it.
Where is your pressure regulator located? Do you have it before or after the rails? They recommend that you put the regulator after the rail so that the regulator acts as a dam vs a control point. Or are you still running the C5 filter combo? If so, your symptoms mimic what you see with other high power cars with that set-up.
Last edited by ShiftyCapone; Jun 29, 2020 at 09:10 AM.
Where is your pressure regulator located? Do you have it before or after the rails? They recommend that you put the regulator after the rail so that the regulator acts as a dam vs a control point. Or are you still running the C5 filter combo? If so, your symptoms mimic what you see with other high power cars with that set-up.
I still have the stock 3/8 lsa rail. Its only has a single inlet and the fuel pump is connected straight to it. I have the regulator tee’d into the supply a few inches before it connects to the rail. The line coming off the tee that I’m pointing at goes to the regulator. Theres then a 3/8 line from the regulator to the tank.
Do they make aftermarket fuel rails for the LSA? Are the ZR1 rails 3/8 as well?
I’m pretty sure the inlet on the ZR1 rail is the same size. They make aftermarket rails but you can do 800+ wheel on the stock lsa rail as long as you have enough pump. My old setup did 530 wheel on the same stingy mustang dyno. We made 508/577 before the pressure drop and pulling out of it at 4200. Thats with no timing or meth yet so our estimates are anywhere between 640-680 wheel at this point, 720-760 dynojet. Obviously I’m planning on doing rails eventually, most likely when I upgrade the feed, but right now I’m trying to get back there so we can finish the tune and make a track rental on the 13th.
Give Aeromotive a call. They are really helpful and possibly can get you the single pump that you need.
Thanks, I gave them a call and they recommended having them build a custom sender assembly with dual pumps for me. So basically twin 340’s like I was thinking. They said the 3/8 line isn’t really enough for a single 340, so I should go to a -10 on both sides. They told me not to run the twin 340’s with the single 3/8, but I’m assuming thats because it could shorten the life of the pump. However they did say the pump diameter is no larger than a 255, so I should be able to get them in the tank. I’m leaving the 3/8 line for now, and I’ll upgrade it whenever I go to a larger rail. My main concern was getting the pumps in the tank, and it looks like I got my answer.
Also -10 seems like overkill, so when I finally get a chance to change the feed line I’ll probably go to a -8. Also the second pump is going to be controlled by the Holley and it’s only going to come on under boost, so longevity of the pumps shouldn’t be a concern.
-10 is way overkill. You can make 1500+ on -8 on gas
the higher pressure kills flow on them walbros. You gotta try to keep total pressure with boost under 65 psi i feel to keep volume up. Lower the better obv from the flow charts. I found the limit to be 1097 whp or so around 65 psi out of a 3/8” line at the tank side that quickly went to -8 feed. That little 3/8 outlet did not allow even 3 255 pumps to make more power without pressure loss.
Last edited by Orr89RocZ; Jun 29, 2020 at 04:14 PM.
-10 is way overkill. You can make 1500+ on -8 on gas
the higher pressure kills flow on them walbros. You gotta try to keep total pressure with boost under 65 psi i feel to keep volume up. Lower the better obv from the flow charts. I found the limit to be 1097 whp or so around 65 psi out of a 3/8” line at the tank side that quickly went to -8 feed. That little 3/8 outlet did not allow even 3 255 pumps to make more power without pressure loss.
Looking at the chart from Aeromotive a single 340 will flow around 260 lph@70psi, so with two pumps I should be where I need to be. And yea that 3/8 feed has to go. I just need it running for a rental coming up in July and with everything else there is to finish up I just don’t have it in me to run a new line right now😂. I had no idea about how much pressure is needed from a pump to overcome a smaller line! I definitely learned a lot about fuel pumps in the last 24 hours.. Anyway pumps are ordered so I’ll post some pics and how the install process went in a few days.
I got a buddy that put twin walbro 450 or 485's in a plastic 4th gen tank. He's running E85 with twin turbo LS set-up. He said they wouldnt go in the 3rd gen tank. IDK if thats any help?
I got a buddy that put twin walbro 450 or 485's in a plastic 4th gen tank. He's running E85 with twin turbo LS set-up. He said they wouldnt go in the 3rd gen tank. IDK if thats any help?
The 400’s and up have a bell on the bottom so they’re quiet a bit wider than the 255’s and 340’s. Would never fit in a 3rd gen tank, but the 4th gen openings are wider.
They fit and its closeeee! I positioned the second pump in front of the first one and hose clamped it at the bottom. I also had to cut off the C bracket that cradled the back of the main pump. I didn’t have a hose clamp to put at the top, but I am adding one. Both socks fit nicely parallel, and I ended up removing the old vent line to fit the second pump output and used the stock 5/16 return line for my new vent. I cut some notches toward the top to prevent any possible siphon affect. I’m probably a little paranoid but that old return I’m using as a vent now is fully submerged in fuel, so I rather be safe than sorry.
All thats left is to hook the return drain hose back up, run the wires out of the tank, and seal the hole with some jb weld. I’m using a -6 Y fitting to merge the 2 pump hoses outside the tank. The best part about this setup is that I can easily upgrade to a -8 feed just by swapping out that Y fitting. I’ll just go to a dual -6 IN to a single -8 OUT and be done with it. Also for the second pump bulkhead I used a -6. I needed the hole to fall right to the left of my old vent, so I reamed the hole out and jb welded a washer over it to make it smaller. The washer seals the hole and raises the fitting up so it can clear the hard lines out of the tank. Last thing I did was bend the return out of the way so I have space for the second pump feed hose. I went overboard on the jb weld and sealed the nut into place as well. As long as I don’t strip that bulkhead, I shouldn’t have to take it apart!
Hit the dyno today and the issue was still there but much better. At the start of the pull pressure spiked at 80 then gradually dropped to 58-60 by around 6200. I think I found the culprit though. I pulled the filter and found the tiny disk pretty stuffed up. There wasn’t anything crazy in there but I couldn’t see light through it before. I also put my mouth on the disk side of the filter housing and tried blowing air through it. It was like blowing through a coffee stirrer! After brake cleaning and blowing it out I can now see through it and blowing air through feels like a regular straw now. I’m gonna do a data log on the street tomorrow and see if it fixed it. Im assuming due to the small surface area of filter material it clogs up with just some light debris.
Where is the fuel pressure gauge relative to the filter? On my car a blocked filter would decrease fuel pressure at the engine.
Do you have a boost referenced fuel pressure regulator? And what does the data overlay look like of MAP, RPM, fuel pressure, injector pulse width, and Fuel Flow?
Where is the fuel pressure gauge relative to the filter? On my car a blocked filter would decrease fuel pressure at the engine.
Do you have a boost referenced fuel pressure regulator? And what does the data overlay look like of MAP, RPM, fuel pressure, injector pulse width, and Fuel Flow?
It was the filter! Here’s the before and after:
The first log was on the dyno, second on the street. I have a Holley fuel pressure sensor mounted on my boost referenced regulator. Before cleaning the filter pressure would drop down below 60 at the top of the pull. My buddy said with a base pressure of 60 and the boost I’m at it, the pressure should be in the 70’s. Before injector duty would start to climb as pressure dropped off. I don’t have the laptop in front of me so I can’t see where it’s at in the second pull, but it should be in check being the pressure is holding. Also if you look at my oil pressure on both logs, the street pull has about 20 psi less than the dyno pull! As soon as I lift the pressure goes back up to the high 60’s. Looks like I’ll be pulling the pan to add some baffles...
question, just out of curiosity, are you paying TTP for all/each of these dyno sessions every week, or is there some type of arrangement you guys have together? I would love to hit a dyno, but the thought of expensive dyno sessions (possibly several of them) that people end up doing after their initial dyno session has me a bit on the fence. what I mean is, I don't want to go to a dyno, make pulls and be told, you should really correct "this" issue and then have to come back a week later and pay again for dyno time.
question, just out of curiosity, are you paying TTP for all/each of these dyno sessions every week, or is there some type of arrangement you guys have together? I would love to hit a dyno, but the thought of expensive dyno sessions (possibly several of them) that people end up doing after their initial dyno session has me a bit on the fence. what I mean is, I don't want to go to a dyno, make pulls and be told, you should really correct "this" issue and then have to come back a week later and pay again for dyno time.
Yea I know what you mean. It’s a lot of money and travel to keep coming back and having the car strapped down again. Just make sure everything is ready to go. When I first put the blower on and had it tuned I had the same issue with fuel. The walbro 400 I got turned out to be a low pressure knock off and the fuel pressure dropped like it did now. At the time I had tunetime look into and repair it, then I picked up the car when it was finished. For my situation my friend does some tuning there plus I help out with repairs once in a while.
The big question? What were the final numbers? Are you fully optimized now and all dialed in?
Nah, I cleaned the fuel filter at home then logged on the street to test it. I’m still figuring stuff out because for some reason my new dc engineering alternator decided to turn off on the dyno for a second causing voltage to drop to 12.6 and the afr to go lean for a split second. I have to call up and make sure that doesn’t happen again, then I need a free day to make it to the dyno again. The car probably won’t be strapped down again until august. So far it made 590 when the fuel pressure was dropping off. Still needs timing, meth, and ice.
Yea I know what you mean. It’s a lot of money and travel to keep coming back and having the car strapped down again. Just make sure everything is ready to go. When I first put the blower on and had it tuned I had the same issue with fuel. The walbro 400 I got turned out to be a low pressure knock off and the fuel pressure dropped like it did now. At the time I had tunetime look into and repair it, then I picked up the car when it was finished. For my situation my friend does some tuning there plus I help out with repairs once in a while.
cool cool, thanks Matt
Thats why I figured I would ask ya how TTp and you had arranged everything. I will have to chat with the local dyno guy around my area and see what he thinks we could do. I would hate to make a session, then have to come back several times if changes in hard parts are needed before perfecting the dyno tune. at full cost. plus I will definitely have to go back there after this winter when I install the 200 nitrous shot. so perhaps I will just wait until march 2021 since the car is running pretty good and I have an engine dyno printout currently showing 531 at the crank. thanks for the info tho!
First off, nice car! Second I ran the aeromotive 340 and it’s a fine pump and very quiet but they suck at high pressure. They have a cap of 90psi but flow drops like a rock after 70psi. You would have been better off with a Walbro 450 high pressure Which have higher internal pressure reliefs. Third whoever told you that 3/8” feed is not enough is full of $hit! In a low pressure high flow like a carb feed line size is more critical but in an EFI situation people are pushing +1000hp on 3/8” line and it’s very common in the boosted LS world. I run 3/8” stock tank line and then run -6 PTFE line which is 3/8” and I have been up to 750hp running +73psi on a walbro 450
and not the high pressure on my turbo 5.3. You would have been fine with -6 unless you need more than 1000hp and if your redoing it’s up to you if you want to run -8 at that time and I’m not sure of your power output. Forth is throw that $hitty filter away! I ran one of those and the screen clogs all the time due to surface area as it’s such a small disk. Step up and get a real filter with a large cartridge and 5-10micron rating to keep the injectors happy. Fifth that braided line in the tank is gona swell and leak or clog up as it falls apart. It does not have a submerged rating so get that $hit out! Go with submergable rubber or fuel tank plastic hose or a PTFe. That braided line isn’t even great for regular use as gas vapors permeate through the thin rubber core and make it always smell like you have a leak and when they deteriorate and clog you will have no idea bc of the stiff outer braid.
with the dual 340s you got a lot more flow but the same lower pressure rating I would have gone with a single 450 high pressure which are only like $100-120 real and I get mine from summit with a price match. That single 450 on pump would support 1000hp ish.
First off, nice car! Second I ran the aeromotive 340 and it’s a fine pump and very quiet but they suck at high pressure. They have a cap of 90psi but flow drops like a rock after 70psi. You would have been better off with a Walbro 450 high pressure Which have higher internal pressure reliefs. Third whoever told you that 3/8” feed is not enough is full of $hit! In a low pressure high flow like a carb feed line size is more critical but in an EFI situation people are pushing +1000hp on 3/8” line and it’s very common in the boosted LS world. I run 3/8” stock tank line and then run -6 PTFE line which is 3/8” and I have been up to 750hp running +73psi on a walbro 450
and not the high pressure on my turbo 5.3. You would have been fine with -6 unless you need more than 1000hp and if your redoing it’s up to you if you want to run -8 at that time and I’m not sure of your power output. Forth is throw that $hitty filter away! I ran one of those and the screen clogs all the time due to surface area as it’s such a small disk. Step up and get a real filter with a large cartridge and 5-10micron rating to keep the injectors happy. Fifth that braided line in the tank is gona swell and leak or clog up as it falls apart. It does not have a submerged rating so get that $hit out! Go with submergable rubber or fuel tank plastic hose or a PTFe. That braided line isn’t even great for regular use as gas vapors permeate through the thin rubber core and make it always smell like you have a leak and when they deteriorate and clog you will have no idea bc of the stiff outer braid.
with the dual 340s you got a lot more flow but the same lower pressure rating I would have gone with a single 450 high pressure which are only like $100-120 real and I get mine from summit with a price match. That single 450 on pump would support 1000hp ish.
Thanks, we were going to throw a 450 in it on the dyno but my tuner didn’t have any on the shelf and summit was backordered. I’m still contemplating throwing one in because I’m really not liking the two pump deal. That second pump turns off and its adios motor. The holley dominator has a function where you can set it to pull timing if fuel pressure drops, but as far as I know I cannot do that with the terminator. I’m contemplating changing the feed line anyway because I currently have it running along the frame rail and I’d like to reroute it to come over the transmission away from the exhaust.
Thanks, we were going to throw a 450 in it on the dyno but my tuner didn’t have any on the shelf and summit was backordered. I’m still contemplating throwing one in because I’m really not liking the two pump deal. That second pump turns off and its adios motor. The holley dominator has a function where you can set it to pull timing if fuel pressure drops, but as far as I know I cannot do that with the terminator. I’m contemplating changing the feed line anyway because I currently have it running along the frame rail and I’d like to reroute it to come over the transmission away from the exhaust.
understood. I never liked the dual pump deal either when the second pump kicks on hour Fuel pressure base increases due to the additional flow so your inputted data is no longer correct. This is because you set the regulator at that single pumps pressure and flow which changes. If you need a bump in fuel flow and pressure you can run dual pumps in series which has less affect one fuel flow perhaps 20% but allows for higher flow at higher pressures. Means you can run higher base pressure and with boost as it raises 1:1 the pumps flow doesn’t drop. Since you seem to be running a GM supercharger your prob maxed around 750/800hp at the crank so your still within the limits of a single 450 but opt for the higher pressure so you don’t have to worry about the check valve opening up and dumping flow.
I have run twin pumps for years and never had an issue if genuine walbros and good wiring. I think the risk of one turning off is rare but anything can happen
finding the right time to engage the second pump helps with the fuel pressure adjustment
if you kick it on early you may see a spike in fuel pressure and thus your ve table may look funny around that spot. Its really no big deal imo but it is something you need to tune for to be optimal
adjustable boost switch is nice, or do it with the holley at a certain boost.
i’ve run a second to kick on at 1-2 psi and third to kick on at 15 before. Worked good, the 1-2 psi did spike fuel pressure slightly but the momentary richness there i didnt care about
I have run twin pumps for years and never had an issue if genuine walbros and good wiring. I think the risk of one turning off is rare but anything can happen
finding the right time to engage the second pump helps with the fuel pressure adjustment
if you kick it on early you may see a spike in fuel pressure and thus your ve table may look funny around that spot. Its really no big deal imo but it is something you need to tune for to be optimal
adjustable boost switch is nice, or do it with the holley at a certain boost.
i’ve run a second to kick on at 1-2 psi and third to kick on at 15 before. Worked good, the 1-2 psi did spike fuel pressure slightly but the momentary richness there i didnt care about
You guys are making stupid horsepower to need so much fuel.. Crazy!
Most are using belt drive pumps or cable drive pumps now with e85 to make the big power. Much better option than messing with multiple electrics
however they did come out with 5, 7, and 10 gpm electric pumps. Cost as much if not more than a belt drive mechanical but make it convenient without the accessory drive issues. Just not submersible. So you sump tank or run a surge tank setup like i do now
Most are using belt drive pumps or cable drive pumps now with e85 to make the big power. Much better option than messing with multiple electrics
however they did come out with 5, 7, and 10 gpm electric pumps. Cost as much if not more than a belt drive mechanical but make it convenient without the accessory drive issues. Just not submersible. So you sump tank or run a surge tank setup like i do now
Have you or can you post pics/more info about your surge tank setup?
I've always felt that this is the smart way to go but I've very rarely seen it done (never in person)
I used a ebay tank i found with 5, 1/2 npt threaded bungs. Its advertised as 1 gal but probably closer to 3/4, maybe touch more by dimensional volume calcs
either way it was cheap and effective. You can use whatever. There are many out there that are expensive and many that are smaller.
i have twin intank 255 lph walbros. -8 feed to surge tank. Filter inline. They run constantly. Main fuel pump is an enderle 110 rated at 11.4 gpm. Abit overkill but i got a deal on it.
For me i chose closer to 1 gal because i expect to consume near 7 gal per min at full power. The twin 255 walbros in tank flow roughly 2.3-2.5 gpm maybe at 0 pressure. So doing the math i figured the near 1 gal tank would last me long enough in a wot 1/4 mile pull plus transbrake time with time to spare.
so the walbros have a -8 feed to supply surge tank. Theres a -8 back to the stock gas tank return port. I have a 4th gen plastic tank. The belt drive mechanical is a -12 from surge tank to pump inlet suction end. -10 to the rails which splits into dual -8 rails, then into the fuel pressure regulator. Single -10 return from regulator to surge tank.
works fantastic. Main lift pump feeds the bottom of tank close to the mechanical -12 inlet line. Returns are at the top. I had a pressure gauge on the top port to see what it does. It hits 2-3 psi at times but drops to 0 under throttle
Has anyone ever fitted dual 340lph fuel pumps in the stock thirdgen tank? I found a few threads mentioning it works with a 4th gen tank due to the larger opening, but not much regarding the thirdgen tank. I'm looking at getting two of these being my 525 hellcat pump turned out to be a chinese knock off.
https://www.summitracing.com/parts/aei-11540
Highly modified to fit in third gen tank. It works great
