EFI pump with carb
EFI pump with carb Posted this in the carb section as well, but hope to get better feedback here. I have a 98 Camaro with a carb LS. Car has a stock EFI pump with -6an feed and return. Return style regulator set to 6.5psi. Question is, would it be safe to run a 150-200 wet shot with the stock EFI pump? I know that pump is more than sufficient for a stout carb motor, but wondering if it is OK with nitrous. Engine is an LM7 with forged pistons. Custom grind cam, with 706 heads milled .020 and ported. Holley intake manifold and a 750 mech secondaries.
Maybe. Best to watch pressure and afr. But i would think u should be ok. I mean u are taking a pump that flows 58psi to 7 psi. Theres still alot of flow and pressure left over.
Or run a simple holley blue pump standalone setup for the nitrous.
Or run a simple holley blue pump standalone setup for the nitrous.
is the return style a bypass FI regulator? or is it a carb regulator set up with a return.? I have an Aeromtive bypass regulator with 2 340 pumps (run E85) and have it setup for 7lbs and holds rock steady.
My nitrous is setup for 7lbs of flow and my reg is set at 7.5 so when I hit the nitrous and run thru the traps I'm right at 7lbs. That's what I would be concerned is what pressure drop you have on the top end. You need to see a gauge when making a pass so you know. I took a long line and taped the gauge on my cowl just so I can see it for testing. once I knew I took it off the cowl area lol
My nitrous is setup for 7lbs of flow and my reg is set at 7.5 so when I hit the nitrous and run thru the traps I'm right at 7lbs. That's what I would be concerned is what pressure drop you have on the top end. You need to see a gauge when making a pass so you know. I took a long line and taped the gauge on my cowl just so I can see it for testing. once I knew I took it off the cowl area lol
is the return style a bypass FI regulator? or is it a carb regulator set up with a return.? I have an Aeromtive bypass regulator with 2 340 pumps (run E85) and have it setup for 7lbs and holds rock steady.
My nitrous is setup for 7lbs of flow and my reg is set at 7.5 so when I hit the nitrous and run thru the traps I'm right at 7lbs. That's what I would be concerned is what pressure drop you have on the top end. You need to see a gauge when making a pass so you know. I took a long line and taped the gauge on my cowl just so I can see it for testing. once I knew I took it off the cowl area lol
My nitrous is setup for 7lbs of flow and my reg is set at 7.5 so when I hit the nitrous and run thru the traps I'm right at 7lbs. That's what I would be concerned is what pressure drop you have on the top end. You need to see a gauge when making a pass so you know. I took a long line and taped the gauge on my cowl just so I can see it for testing. once I knew I took it off the cowl area lol
Just like anything else, 150 might work perfect then an extra 50 is what breaks the camels back. Mine was great at the 150 level. Once I went 200 is when I started to have issues. Became more critical then. As long as it's a carb return regulator for FI pumps I would assume safe would be 150 level. But you need a gauge to see so it doesn't go lean
TECH Junkie
Joined: Dec 2012
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From: Iowa
Stock Pump is usually good to safely support 400 hp but that is at 55 ish psi. Running the pump at a lower pressure almost always results in a significant increase in volume. I would say you'd have no problem at all at a 150 or 200 with the stock pump. Attached is a pump data sheet for a walbro pump. Its not the same as stock, but you can easily see how pressure vs volume relationship works.
As with any nitrous setup, start small, and creep up on the tune up. If you see things getting lean, find out why and address it. Don't just throw in the 200 pills and hope for the best.
As with any nitrous setup, start small, and creep up on the tune up. If you see things getting lean, find out why and address it. Don't just throw in the 200 pills and hope for the best.
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not sure if you ran high pressure before, but in high pressure you can drop a few pounds and still be safe. Unlike in low pressure dropping 1 or 2 pounds can be bad as the percentage of fuel changes greatly. If your jet chart has different fuel pressure rating you can see how the fuel jets changes just dropping 2 pounds or running 2 pounds higher. On your high pressure fuel jets it's almost 10 pounds difference before you see any changes on the chart.
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Verdad Gallardo TECH Junkie
Joined: Dec 2012
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From: Iowa
Yes, I have run low pressure and am fully aware of just how extreme fuel pressure changes can be at lower pressure levels. half a pound of pressure at 5 psi is 10% swing where at 50 psi, it takes 5 pounds to get the same swing.
Many nitrous guys tune by changing fuel pressure for nitrous only on the regulator rather than change jets sometimes because the changes are so precise. I only shared that chart to show how you increase fuel volume (which is what you need for more horsepower) by decreasing pressure. At 10psi on that chart you're at nearly 75 gph whereas at 60psi you are only going to flow 50. So, by decreasing the pressure the stock pump operates, you should see more flow volume potential out of it.
Like I said, start small, keep an eye on things. If you can either set up a gauge you can see, or log fuel pressure even, you can tell when there is just not enough volume and stop before you hurt anything.
But, if you're not sure and don't want to risk it, you can always just throw a larger pump in for pretty cheap and get that added security.
Many nitrous guys tune by changing fuel pressure for nitrous only on the regulator rather than change jets sometimes because the changes are so precise. I only shared that chart to show how you increase fuel volume (which is what you need for more horsepower) by decreasing pressure. At 10psi on that chart you're at nearly 75 gph whereas at 60psi you are only going to flow 50. So, by decreasing the pressure the stock pump operates, you should see more flow volume potential out of it.
Like I said, start small, keep an eye on things. If you can either set up a gauge you can see, or log fuel pressure even, you can tell when there is just not enough volume and stop before you hurt anything.
But, if you're not sure and don't want to risk it, you can always just throw a larger pump in for pretty cheap and get that added security.
TECH Junkie
Joined: Dec 2012
Posts: 3,615
Likes: 1,327
From: Iowa
I figured as much, but I figured the extra info couldn't hurt anyone that was going to read it. I've seen your name around here before, and you've definitely ran the numbers to back up any info you want to share! ps (not to thread jack but) I've sent you a pm with a question about your fox. I'm just another guy trying to spray my way to glory with a fox haha
your absolutely right, I always look for advice and see how others do it, and see if their is a common ground from the advice I get and then decide accordingly. Oh and the comment "know it all" was meant in a bad way, sometimes when you type something it doesn't come out right what you meant lol.
Carb with Fuel Tank Return Hi Jimmy, you use the BEST method to "fuel" a Carburetor, a return system.
I use the SAME method with many race cars, ones that run a restricted class with a carburetor requirement.
We use our EFI pump with this method (return system) always.
There are many benefits such as keeping air out of the fuel, the fuel is much cooler at the carb and the fuel tank is kept MUCH cleaner.
These cars are used for Off Road Racing and they are often long races.
My small EFI fuel pump will flow twice the volume at 3-6 psi, 2X more than when at a pressure of 43.5 psi.
Thus your 200 NOS should be safe.
Lance
I use the SAME method with many race cars, ones that run a restricted class with a carburetor requirement.
We use our EFI pump with this method (return system) always.
There are many benefits such as keeping air out of the fuel, the fuel is much cooler at the carb and the fuel tank is kept MUCH cleaner.
These cars are used for Off Road Racing and they are often long races.
My small EFI fuel pump will flow twice the volume at 3-6 psi, 2X more than when at a pressure of 43.5 psi.
Thus your 200 NOS should be safe.
Lance