LOW Fuel Pressure With Your
AIR DOG AND FASS PUMP?
INCREASE YOUR HORSE POWER AND FUEL PRESSURE
WITH YOUR HOT P7100 CUMMINS
* OFV060HP Use with super street performance Cummins trucks.
* Fuel pressure range of 43 to 50 PSI.
* Raises fuel pressure at full power.
Do you experience low fuel pressure at wide open throttle (WOT) and just accept it as normal? Have you ever thought that low fuel pressure gives your competitor an edge?
Anthony Reames, the technical manager at Air Dog, asked us to solve the low fuel pressure problem with the Bosch P pump. Cummins owners report that the fuel pressure drops to as low as 16 PSI during full throttle runs. We jumped on this technical request because we thrive on a challenge. Solving problems is what Tork Teknology is all about.
The first thing we did is throw all assumptions out the window. We found that in most cases, they can be very misleading. Our slogan, that we live by, is "one good test is equal to a thousand expert opinions". This is how we attack a problem.
After installing an Air Dog II DF165 on our '98 Dodge Cummins test truck, we routed the 1/2" feed line to an accurate flow meter and ran all the return fuel through an additional flow meter. The fuel pressure was monitored by a glycerine filled pressure gauge. The results (shown left) align exactly with proven hydraulic formulas. Fluid will flow a specific volume through an orifice at a specified pressure and specific gravity. Simply put, a fluid will flow more volume (gpm) as the pressure increases through the same size orifice. Put another way, reduce the orifice diameter, and the GPM flow will drop.
You may have asked yourself why Air Dog and FASS equipped Dodge Cummins trucks will show good fuel pressure at idle and cruise, but the pressure drops at full throttle, to as low as 16 PSI. Take a look at the photo above. The flow meter indicates diesel fuel flow of 1.09 GPM. This is the volume of fuel flowing thru the inlet orifice at the base of the overflow valve. (see photo right) Actually, it translates into 1.14 GPM (multiply number by 1.0495 correction factor) flowing into and out of the P7100 pump. That is the volume of fuel flowing back to the tank through the Cummins overflow valve. Yes, we tested both the Bosch and Tork Tek overflow valves. If you are using one of the old Bosch valves with the .168 inlet orifice, your fuel pressure will never allow you to win ANY competition event becuase of very low fuel pressure.
ELECTRIC PUMPS DO NOT WORK WELL WITH THE P7100
I'm not saying that the Air Dog and FASS are not good pumps. Both are quality pumps. The problem is the orifice leakage is too large and bypasses too much fuel to tank. This leakage produces low fuel pressure at WOT.
We now know that the inlet orifice on a standard Bosch overflow valve will flow 1.14 GPM back to tank. This is how it lowers your fuel pressure and kills your Cummins diesel performance! If you run an AirDog 100 GPH (gallons per hour) pump, you are pumping 1.66 GPM. (100 GPH divided by 60 minutes/hour = 1.66 GPM) You are losing 69% of your pump volume thru the overflow valve. That's almost 75% of the fuel doing no work at all! Let's do the numbers for the Air Dog II DF165 which is rated at 2.75 GPM. If you lose 1.14 GPM to tank, 41% of your pumps capacity is LOST. Let's suppose you use the AirDog II DF200 which flows 3.33 GPM. 34% of the pumps capacity is doing nothing for your performance 12V Cummins.
It's easy to see why performance P pump users are showing low fuel pressure at WOT. Too much diesel fuel is pumped through the Bosch overflow valve and back to tank. This translates into lower HP and torque performance numbers with your Cummins 12V. It could make the difference between winning or going home defeated.
Another problem that we uncovered was at a very specific pressure, the fuel flow through the overflow valve can be dead headed. This can be dangerous as the P pump needs fuel flow to help keep it cool. If you set the AirDog pressure regulator to slightly less than the OFV setting, fuel flow and pump cooling STOP. Also if you adjust the OFV by adjusting the shims, stretching the spring or adjust the Tork Tek overflow valve, the same problem can exist. The solution had to cure low fuel pressure and eliminate any possibility of stopping fuel flow thru the valve.
WHAT ABOUT INJECTION PUMP COOLING?
We know from testing the Cummins 5.9 fuel system, with the stock lift pump, that fuel flow is .59 GPM (max) at 2200 RPM. The engineers at Bosch spent a lot of R & D time to make sure the P pump stayed cool at the fuel flow the lift pump delivered. The Bosch P7100 injection pump will run without problems for 300 to 500,000 miles or more! There are commercial trucks that have seen 1,000,000 miles with the P pump and the Cummins lift pump.
The smallest of the four valves is the OFV070HP. This valve is for super modified, race only trucks. The 070HP orifice will flow .565 GPM at 45 PSI. So, even with the smallest of the valves, you will still be within 4% of the cooling capacity of a stock system.
THE NEW HP OVERLOW VALVE - A TESTED SOLUTION
How did we test for a solution? We machined 12 prototype overflow valves with replaceable orifices, similar to Holley carb jets. The beta testers could now replace the jet with a smaller one to the point where the fuel pressure was aceptable at WOT. In other words, the fuel pressure remained constant from idle to full throttle. Each jet change and fuel pressure reading was documented on a chart. In addition, I made the same tests on our '98 Dodge Cummins 12V.
It became clear after the testing was complete, which sizes cured the problem. Each size created a fuel pressure range at WOT. We also discovered that a very small change in orifice size will make a dramatic change in fuel pressure and fuel flow.
FUEL PRESSURE MAKES HORSE POWER
To illustrate how fuel pressure can affect Cummins diesel horse power and torque, one beta tester asked his brother to try the prototype valve on a dyno. The owner of Left Coast Diesel made a run with a standard Cummins OFV and then installed the prototype Tork Tek HP valve. The first thing he noticed was consistent fuel pressure across the RPM band. No other changes were made to the engine. He achieved a 27HP increase for 3 minutes worth of work. His power increased from 663HP to 690HP at 93 MPH. That 27 peak HP increase can be the difference between winning and losing.
This is what Chad had to say when he tried the new valve. "My truck for sure picked picked up power in the top end. It never really keeps spinning the tires when I open it up in overdrive at 70, but now they just spin to the point I let off because its still going sideways at 100mph".
Our original intention was to offer the valve as an overflow kit with 10 different jets, but the cost would be very EXPENSIVE at $150.00 each. We came up with a better product for MUCH less!
The OFV060HP has the third smallest orifice for highly modified Cummins diesel engines. Your truck is street driven. Your fuel system, engine and turbo have been modified. Your horsepower will be in the 500 to 600HP range. This valve is for super hot Cummins performance trucks using an AirDog, Raptor or FASS pump. Yes it can be used for P pump conversions on the 24V Cummins.
What fuel pressure should you be running? Here is a general rule to determine the fuel pressure you should be at. Multiply the governor spring rpm (in thousands) times 10. In other words, you want 10 PSI of fuel pressure per 1000 RPM of govenor speed. If you installed a 3K govenor kit, you need a minimum of 30 PSI at full power. A 4K kit requires 40 PSI at WOT. 5K equals 50 PSI. Remember, this is at full power, not idle or cruise.
Fuel pressure will be in the 43 to 50 PSI range if you add the 40 PSI spring. The standard spring will limit the fuel pressure you can reach. If you are using the original Air Dog pump, it is factory set at 30 PSI. If you want higher fuel pressure, you will have to install a 40 PSI spring. The AirDog I and II use different springs to achieve higher fuel pressure. They are not interchangeable. Please note that you will not achieve higher fuel pressure by swapping out the spring. You have to fix the leak first.
Do not use the HP valve on a stock fuel system! This valve will raise pressure spikes to the point that the stock fuel filter canister will blow a seal. The valve is intended for Cummins P7100 trucks using a FASS, Air Dog or high volume, performance fuel pump only.
You built a performance Cummins to win! Don't let low fuel pressure rob you of the horsepower you built into your Cummins. Order a Tork Tek OFV060HP today and see the difference it makes in your Cummins performance. At $27.99, it will be the cheapest performance mod you ever made. ORDER TODAY!
Would you like to know more about the diesel fuel system?
We are in the process of writing a six part article series on the diesel fuel system. Many of the examples used were based on the Cummins, but the principles will work on the Duramax and PowerStroke too. All of the formulas, on sizing the different components, also apply to gas engines as well. Each article covers a specific area of the diesel fuel system. Article number one deals with the the low efficiency of the Cummins lift pump. Article number two is a very in depth look into the inlet line and how it affects the horsepower that your engine can produce. Feel free to post these articles on the forums or share them with your performance friends.
5 Star Rating
Posted by Past Reviews on May 11th 2016
Easy Install for Peace of Mind
Posted by Seth Niebaum on 24th Apr 2013
I won't make any rash statements but I know this, my idle FP is now almost 55psi(versus 45psi before)... For a few minutes of work that anybody can do, I have peace of mind that I will have all the fuel pressure I need on a built Ppump 24valve. Even if you don't think you have fuel pressure issues I think it's worth 10 minutes (or less) of your time to install.
Posted by Bobby Jackson on 29th Oct 2012
months and months ago, i bought both your 14mm gauge snubber and tork tek 060 OFV and wrote a review about it. It wasnt very detailed because of how excited and amazed i was by your product. And i just wanted to send a private email and let you the people of Tork Teknology know that i stand by & behind your products 100% After the install of the 060 OFV, the first thing i noticed on start up was how smooth it made my truck run. It never ran rough but it seriously made it run that much smoother. Also, the HP gain. To Be honest my pump is not benched and alls i have done is LOTS and LOTS of tuning and put in a set of CDS 5k GSK's. It made good power but again, after the install of the OFV my truck fueled harder and maintained costant fuel pressure from no throttle to WOT. Im really unsure of how much HP i actually gained but when driving the truck, its a dramatic change from before and after the OFV!! And lastly, when im driving the truck normal around town or on the highway, i have noticed and gained 5 MPG's! At some point in time, i will re-install my old ofv and collect hard data to provide and show legitimate proof of fuel milaeage gains, hp gains, fuel pressure gains & sustainability, and as well as longetivity. Im just really super happy with the product, and always recomend it to people looking for OFV's, and in that case any product from tork teknology. Again, thank you for putting your hard work and time into these quality A+++++ parts!
Posted by Unknown on 22nd Jan 2012
Small but amazing, very happy I bought this item!
No more long crank and hard starts!
Posted by Austin Jenson on 10th Jan 2012
I was having long crank and hard start issues after doing a p-pump conversion on my 24V. I bought the OFV060HP valve and my problem went away and my truck actually idled smoother than with the factory valve. I recommend this valve to anyone looking for performance and fuel pressure gain.
A Must For Electric Fuel Pumps on a '98 12 Valve cummins
Posted by Micah on 10th Jan 2012
After installing an AirDog Raptor 150 fuel pump I had issues with the fuel pressure fluctuating between the tow presure regulators ( so to speak ). After installing the OFV 060HP it cured the problem. Thanks for all the research you guys do so we dont have to. Sure makes life easier.
I now have good fuel pressure!!
Posted by Bobby Jackson on 6th Dec 2011
Sorry To bother, but i purchased an ofv060 and a 14mm gauge snubber from you guys last week, or the week before, and i cant thank you enough for such a great product. Really happy with both parts, and the overall performance with the ofv. As soon as you guys can get some stickers i would love to have one on my truck! hopefully soon i will be getting the 12v valve spring compressor from you guys, well thanks again for the great products and have a good one!
Posted by matthew on 20th Sep 2011
I put the 060 ovf in a few weeks ago, and I have to say it has made a huge improvement in daily driving as well as full throttle abuse. The pre-boost HP difference is incredible, I didn't expect to feel anything but its deffenitly noticeable. Amazing product as well as a great price.
GREAT PRODUCT AND GREAT SERVICE!
Posted by Jake Patterson on 13th Jul 2011
order the ofv late on a wensday evening and recieved it on friday. excellent customer service when i spoke on the phone with them and speedy delivery. noticed that the truck runs stronger on top end, i dont have a fuel pressure gauge yet so i dont know how much i gained in psi. great company that id recommend to anyone and will do business with again. Plus its made in the USA!
Simple and does the job!!
Posted by Kris Flutty on 8th Jun 2011
All I could get was 38 PSI at wide open throttle. The OFV060HP brought me up to 45 PSI. GREAT PRODUCT.
no fuel pressure drop
Posted by Unknown on 9th Apr 2011
I installed the ofv60hp and even at wide open throttle my fuel pressure is 45 psi. thanks Rob!
Good solution to low pressure and hard starting with HP P-Pump's
Posted by Lee Foreman - Foreman Motorsports on 7th Apr 2011
I was having hard starting and low fuel pressures on my 13mm P-pump 12v. I ordered and installed a OFV060HP, it was very simple to install and took care of both problems. I reccomend one for anyone with a big pump and aftermarket fuel system!
Regained missing Fuel Pressure
Posted by Mark on 4th Apr 2011
My stock OFV was failing and I wasn't getting all 40 psi I should have been getting from my AD150. I was even starting too blame the Airdog as the problem. I replaced my stock OFV with this one and like magic, I had 45 psi! It's less expensive than any ebay junk and works 10X better. Came with new bajo washers to boot.
Find Similar Products by Category
Customers also viewed