Fuel Delivery

Magnum Powers

Registered User
Hi Guys!

As some you know I’ve been developing a supercharger kit for the Ford modular engine. The first kit fits the Mustang 99-04 GT and is being sold under the Tork Tech Inc banner. The kit is just now hitting the market and you can review my latest venture at www.torktech.com.

In the process of developing this kit I came across an issue I think the Supercoupe community should consider. The 4.6L 2-valve engine has rather sickly connecting rods that can’t take more then about 400 foot pounds torque without breaking so we adjusted pulley sizes so the standard kit would produce a torque and hp number that would leave a stock engine intact. We ended up running 10-psi boost making about 400 torque and 400 hp with the standard kit that uses a Focus SVT fuel pump that is rated for 255 lph.

Now comes the interesting part. The Focus pump at 5800 rpms was nearly maxed out at 95% duty cycle, making 400 hp at 10-psi boost!

I am not sure of the exact number without doing some research but I am sure there are well over 100 Supercoupes out there with the MPx running 25% overdrive, some are upgrading to the 30% kit as well making 18-psi boost or more. A few years back we made 390 rwhp with the MPIII running 15% overdrive up here in the Northwest and we also saw about 15 hp for ever 5% increase in overdrive. So, I figure if all things are well and in order there are a lot of SC’s that should be running around 420 rwhp with the MPx or at least wanting to do so.

And this brings me to my concern: If a 255lph pump is max’ed out delivering enough fuel to support 400 hp at 10-psi boost it must not be able to supply enough fuel to support 400-420 hp at 18-psi!

So, I am thinking at high rpms the fuel pressure across the injectors must be dropping. The tuner of course would compensate for this by increasing the fuel injector duty cycle to keep the a/f ratio correct however the injector would be supplying the fuel at a reduced pressure causing the spray pattern to be less then ideal.

Now, if the fuel pressure is indeed low the fuel pressure regulator will have closed the return hose back to the fuel tank completely. Now when the car starts to accelerate there will be an additional pressure drop in the fuel line due to G forces that will reduce the fuel pressure even more. So, if the car was tuned on a dyno to the proper a/f ratio when going down the track the car will run lean. FYI, I burned a hole as big as my thumb in one of my Lightning’s Probe pistons due to loss of fuel due to acceleration, in that case there was not enough gas in the tank.

I can’t say this is a “real” problem or just a potensial one however it is an issue that someone could investigate and report on. BTW, there are a lot of Mustang speed shops that will not release a supercharged 400hp Mustang GT out of their shop without a 03-04 Cobra dual fuel pump fuel tank, something to think about…..

Cheers,
Charles

Also, thanks for your support: Magnum Powers’ Supercoupe sales have been quite good this year, thanks so very much!!!
 
I've heard of people reaching around 475rwhp before they start maxing out the fuel pump. That doesn't necessarily mean pressure wasn't trailing off before then, though.

Most people at the 400rwhp level are running methanol injection, as well. Doing this will lower the duty cycle and fuel consumption.
 
I saw the kit when I was down there. Clean look with intercooler built in. I heard there was going to be magazine coverage. Nice to see some aftermarket competition for KB and Roush.
 
I've heard of people reaching around 475rwhp before they start maxing out the fuel pump. That doesn't necessarily mean pressure wasn't trailing off before then, though.

Most people at the 400rwhp level are running methanol injection, as well. Doing this will lower the duty cycle and fuel consumption.

Good point about methanol. Are you sure the 475hp guy is not running a KB boost-a-pump?
 
I'm sure he'll step in soon to say something about it, but this was without a KB Boost-A-Pump. He has one now as a result of maxing out the Walbro, on nitrous.

He is running a twin screw blower, which lowers the BSFC of a motor. With a the higher BSFC that the M90 uses, it should lower the max HP level to around what you suggested. So I must say, a good point you bring up.
 
I saw the kit when I was down there. Clean look with intercooler built in. I heard there was going to be magazine coverage. Nice to see some aftermarket competition for KB and Roush.

There are two articles coming: one in 5.0 and the other in Super Rod, both stock engines.
 
were are you guys located in the northwest?

Magnum Powers is located 40 miles west of Portland Oregon. Fast Specialties, a speed shop with a Mustang Dyno where the installation for the article was done is located on Minihaha (slightly funny street name) in Vancouver, WA.
 
I believe there is a TSB about the new mustangs have air bubble problems around the fuel pump area. Something you might want to look into also.

-Mike
 
The two pump trick has been standard fare on high horsepower Gen 1 and Gen 2 Lightnings for some time now. It probably is something that high horsepower SC's should be thinking about.
 
Good point about methanol. Are you sure the 475hp guy is not running a KB boost-a-pump?

Charles,

My car has the 255 lph high pressure pump, a 6AN supply line, 60# injectors, billet fuel rails and a remote mounted Aeromotive adjustable regulator. I've also got the snow injection system and using a large single nozzel. It's able to pull 425-435 rwhp through an AOD with non locking conveter without running out of fuel on the dyno.

The wet nitrous system I'm using taps into the 6AN line just prior to the fuel rail and when testing it on the dyno shortly after installing the AR blower. With only a 75 hp fuel jet (with a 100 hp nitrous jet) we discovered that at around 475 rwhp, the motor started going very lean. Increasing the injector pulse width did nothing to correct the situation so we concluded there wasn't enough fuel pump capacity.

The easiest solution in my case was to add a KB boost-a-pump with intentions of only using it when spraying nitrous. After installing I went back to the same dyno to test the nitrous system and after making a few pulls concluded that a 30% increase in voltage was required to spray the nitrous and pull around 525 rwhp without going lean.

After adding longtube headers and a larger exhaust system the tune was all out of whack and I've had to leave the boost-a-pump set at 10% increase to make 425 rwhp without going lean on the top end. I'm sure that won't be necessary after getting the tune dialed in. I think I'm able to make a little more power on the 255 lph high pressure pump because of more efficent twin screw blower and the use of methanol injection.

With a roots blower and no methanol or voltage increase to the pump, I would agree with your concerns of trying to exceed 400 rwhp on a single 255 lph pump.

Since I wanted to keep the stock tank on my 93 and still have enough fuel for 800 rwhp, Dave Dalke modified the pump and float assembly to accept a 2nd 255 lph high pressure pump. In addition to a dedicated electrical circut we ran dual 6AN supply lines and a single 6AN return line. It's been working perfect since 2004 with that configuration. There are a few pictures of the dual pump stuff in this thread.

http://www.sccoa.com/forums/showpost.php?p=307888&postcount=1

David
 
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Since I wanted to keep the stock tank on my 93 and still have enough fuel for 800 rwhp, Dave Dalke modified the pump and float assembly to accept a 2nd 255 lph high pressure pump. In addition to a dedicated electrical circut we ran dual 6AN supply lines and a single 6AN return line. It's been working perfect since 2004 with that configuration. There are a few pictures of the dual pump stuff in this thread.

http://www.sccoa.com/forums/showpost.php?p=307888&postcount=1

David

Is the second pump strictly for the n2o? It looks like 2 lines out, one back in which seems like your pumps are in parallel rather than serial.
 
Is the second pump strictly for the n2o? It looks like 2 lines out, one back in which seems like your pumps are in parallel rather than serial.

No...the 93 is the turbocharged v8 SC and it doesn't have nitrous. Both pumps run all the time and yes they are parallel with one pump feeding each fuel rail. I just showed the pictures because the same thing could be done on a 3.8 SC.

David
 
Charles,

My car has the 255 lph high pressure pump, a 6AN supply line, 60# injectors, billet fuel rails and a remote mounted Aeromotive adjustable regulator. I've also got the snow injection system and using a large single nozzel. It's able to pull 425-435 rwhp through an AOD with non locking conveter without running out of fuel on the dyno.

The wet nitrous system I'm using taps into the 6AN line just prior to the fuel rail and when testing it on the dyno shortly after installing the AR blower. With only a 75 hp fuel jet (with a 100 hp nitrous jet) we discovered that at around 475 rwhp, the motor started going very lean. Increasing the injector pulse width did nothing to correct the situation so we concluded there wasn't enough fuel pump capacity.

The easiest solution in my case was to add a KB boost-a-pump with intentions of only using it when spraying nitrous. After installing I went back to the same dyno to test the nitrous system and after making a few pulls concluded that a 30% increase in voltage was required to spray the nitrous and pull around 525 rwhp without going lean.

After adding longtube headers and a larger exhaust system the tune was all out of whack and I've had to leave the boost-a-pump set at 10% increase to make 425 rwhp without going lean on the top end. I'm sure that won't be necessary after getting the tune dialed in. I think I'm able to make a little more power on the 255 lph high pressure pump because of more efficent twin screw blower and the use of methanol injection.

With a roots blower and no methanol or voltage increase to the pump, I would agree with your concerns of trying to exceed 400 rwhp on a single 255 lph pump.

Since I wanted to keep the stock tank on my 93 and still have enough fuel for 800 rwhp, Dave Dalke modified the pump and float assembly to accept a 2nd 255 lph high pressure pump. In addition to a dedicated electrical circut we ran dual 6AN supply lines and a single 6AN return line. It's been working perfect since 2004 with that configuration. There are a few pictures of the dual pump stuff in this thread.

http://www.sccoa.com/forums/showpost.php?p=307888&postcount=1

David

Thanks Dave for sharing your fuel system with us. The only other guy I am aware of who has a fuel delivery system even close to the capabilities of yours is Kevin. From my end of thing here at MP I know there are more then 100 Supercoupes out there that are moving enough air to need a fuel system with simular capabilities but are running really just stock fuel systems with a pump that is undersized for the task at hand. It would be a good thing if someone came up with an upgrade kit or list of parts that would supply an adequate amount of fuel for say 450 rwhp or so running a roots type charger.
 
I was alway nervous about running out of fuel so when I went the fuel cell route I also went way over the top with the fuel system. Fuel cell, A-1000 pump, -08 supply, -06 return lines, remote fpr, running 60 lb injectors on a modified stock fuel rail......I darn well better NEVER run out of fuel.
 
I was alway nervous about running out of fuel so when I went the fuel cell route I also went way over the top with the fuel system. Fuel cell, A-1000 pump, -08 supply, -06 return lines, remote fpr, running 60 lb injectors on a modified stock fuel rail......I darn well better NEVER run out of fuel.

This raises an interesting question. What is the comparative benefits of the Boost-A-pump versus high capacity fuel pump??

Ira
 
The real question would be Boost-A-Pump on a Walbro versus an external high capacity pump. You can put a Boost-A-Pump on a high capacity pump, too.

An A1000 fuel pump can support around 1400HP and has plenty of flow to run the recommended -10AN supply line to the fuel rail. It's max pressure is 90psi, as well.

If David is already 30% increase in voltage then the Boost-A-Pump would around 600rwhp.

I'm running an A1000 pump, fuel cell, dual -8AN on the inlet of the pump, -10AN supply to the rail, inline FPR, a 1/2" (-8AN) fuel rail, and a -6AN return. It really is a complete overbuild, but you're left with no worries.

Also, the A1000 is completely submersible, so it's possible to put one in a stock tank.
 
There are trade-offs to every upgrade. Aeromotive offers a pump speed controller to run low voltage to the pump while cruising. Life expectancy is "shorter", but it's life is still abundant.

Most people don't daily drive their 450+rwhp car anyways.
 
i really don't like the idea of running the boost a pump. one bigger pump is much better route to go. when running 2 pumps and one of them dies, you will never know it until the engine blows because of the lean condition. where as with one pump. if it dies, the engine will simply shut down.
 
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