looks like i'm gonna start spraying the car before the end of the year, but i need to upgrade my fuel system. currently i'm running a stock '85 z28 replacement mechancial pump and stock sized tubing (actually, i'm running -6 from behind the back seats forward...stock fuel lines kept kinking and breaking). i'm planning to use the NX Hitman kit. so far i'm really unsure how to run the fuel system...so i'm gonna say what i think i should run and you guys correct me where i'm wrong. i want to run a single pump for both the motor and the nitrous, so i know it's gonna have to be quite the pump. suggestions? from there, i'll run my -6 line up to a fuel block y-junction. splitting off into two regulators. one will go to the motor, and the other to the fuel side of the nitrous system. is this the right way to do it? will i need more initial volume? like a -8 or -10 line? what regulators should i use? what fuel pump should i use? what problems might i see using a dual plane intake (holley street dominator, idle-7200) i want to make sure that it has pleny of volume, cause i would eventually like to hit the motor with the maximum with this kit, which is a 200 shot, but i don't want to run into detonation issues. the motor is not really built for the nitrous and i guess i really don't care if it blows up, but i don't want the reason it blows up to be a lean condition. rings touching together or beating the ring lands closed is another story that i can live with(hey, after all it is just a budget 305) and i've got a 383 in the works with a fully forged bottome end and i am file fitting the rings loose so they have room to grow when i hit them with the kit. car has already been 12.50@106.8mph with this little 305 n/a and i'm still taking weight out and tuning the car and hoping to have it in the very low 12's n/a. i'd like very much to see a 10.99 pass on a hit.

I run a single pump config now, a Mallory 250 Comp pump. The filter is a BG5000 that I bought off of here somewhere and I run 1/2 inch hard line to a y-block. I installed a 1/2 inch pickup tube into the stock tank, drilled out one of the other lines that was closest to the stock pickup and ran the 1/2 inch right along side it.

The one thing that bugs me is the nitrous side regulator, think it needs to be a return style to work properly. Right now the gauge just pegs out unless you activate the nitrous fuel solenoid. If I were to use a return style it wouldn't be dead headding into the solenoid and should show the pressure correctly. The carburetor side works just fine.

The pump puts out a lot of volume, the sucker will shoot a stream of fuel from a -8 line pretty far. Drawback is it's freakin loud. It's rubber mounted and the lines are all in those insulated clamps but it's still pretty loud. My exhaust covers it somewhat though Dual plane intake, think I read that you should only use up to 150 hp shots with those using a plate system. You might do some reading on that.

I built my fuel system probably a bit overkill just because the plan at the time was going to have a blower plus nitrous or a bigger engine. It has room to grow and now I don't have to worry about redoing another fuel system for quite some time.

I have never heard of hard steel stock type fuel inkes kinking and breaking. I use double wall steel tubing for just about evenything and have never had a problem. That -6AN is actual smaller on the ID than 3/8" steel tube so it flows less than the stock lines.

There really isn't a right and wrong way to do. It usually is defined by what parts you already have and what they are capable of. Since you are starting fresh then it depends mostly on how far you want to upgrade the HP later.
Here is some answers to your questions:
1) right way? ANS: that is one way to do it. Make sure you install a return line for the second regulator.
2) Will I need more intitial volume? ANS: It depends on your fuel pressure
3) regulators? ANS: I like the cheapo MSD vacuum/boost referenced ones. It all depends on your fuel pressure
4) what fuel pump? ANS: Assuming a 3300# car and 12.50 sec puts you at around 400 FWHP. You want a max. of 200HP additional HP fro 600 HP total. Since your engine runs at between .45 BSFC to .65 BSFC I will use the worst case .65 BSFC so you need 600*.65 = 390 #/hr of fuel. A gallon of fuel weighs about 5.8#s. So, you need about 390#/5.8 = 67 gallons/hr maxed out.
You are on the fine line of using a Walbro 255. You might have to go into the big buck pump league. Do the calcs for your engine it may use less fuel per hour.
5) dual plane problems? ANS: not sure. I remove carbs because I can never get them to work properly.

OK, the car weighs 3170lbs with me in it.

the lines kinked and broke cuase the car was originally a fuel injected v6 with the lines on the driver's side. i converted it over to the carbed sbc with mechanical pump that's in the car now, but i moved the hardlines up and over the tranny like the factory mechanical pumped cars did...i suppose my half-a$$ed attempts at bending stuff made the possibility of kinks and cracks more probable...anyhow, i've got it fixed with -6 line and AN fittings for the moment.

so going to a 1/2" line might be better than eh? what did you do to get that line to seal to the fuel pickup?

as far as fuel pressure goes, the stock pump has always worked fine for this motor and the last(which actually made more power...more cubes has that tendancy, lol!) and i'm gonna guess it's around 5psi

will i need to run a fuel return off of both regulators or just the n2o side of things?

what is the .45 BSFC and .65 BSFC thing your talking about? not sure what those numbers are in reference to.

BSFC is brake specific fuel consumption, and is basically the rate of fuel consumption divided by the rate of power production.

BSFC = ( Fuel flow lbs per hour) / (BHP)

and how would you figure out the fuel flow lbs per hour? thing gets 22mpg on the hwy if that helps...

how 'bout this pump by BG? price is in my range...

JEGS High Performance - Barry Grant 220HR Electric Fuel Pump

Well typically you need .53 lbs of fuel per 1 horsepower (flywheel), so take your hp rating with the size nitrous shot, multiply by .53, and then whatever comes up will be the lbs/hr requirement...

That pump flows 220 GPH, and a gallon of gasoline ranges from 5.8lbs to 6.3lbs according to a couple of websites from google searches...supposedly premium weighs more...

OK, so say i make 600hp total with n2o

600*.53=318lbs/hr

say the gasoline i use is 6lbs. at 220GPH*6lbs...the pump will flow 1320lbs/hr...which is MORE than enough...could be argued that i could go with less pump...unless my math is flawed...

and actually, with what junkcltr was saying and i only need a 67gph pump...i could actually get away with one of these:

http://www.jegs.com/webapp/wcs/store...tegoryId=10305

which i wouldn't be totally adverse to seeing as i kinda like my mechanical pump...it's very simple and straight forward

does anyone have any experience with these?
http://www.jegs.com/webapp/wcs/store...tegoryId=10305

I did my calcs based on EFI, not carb. I didn't realize you were carb until after the calcs. So, I have mislead you. That Walbro 255 pump is an EFI pump and will flow 67 GPH at max. voltage and normal EFI fuel pressure (43ish PSI)

What I posted was correct for EFI.......here is the BUT part. Those calcs showed you have no room for safety margin. You need safety margin. When you launch your car there is lateral acceleration pushing that fuel back to the pump so you lose pressure when you launch.

One thing you have to keep in mind is flow (GPH) vs. fuel pressure (PSI). As PSI goes up then GPH goes down. It is the law of physics and your pump and fuel line apply. You are in luck, since you are carbed, you use less PSI than EFI, so GPH goes up for you.

Here is the kicker.......that pump you posted DOES NOT say what it flows at a certain PSI. It says 220GPH at free flow.....or zero PSI. Now remember, GPH goes up as as PSI goes down. So at 0 PSI it will flow 220 GPH. Who knows what that pump will flow at 10 PSI for your carb. You need to find out from the manufacturer what it will flow at the PSI you run your carb at.

I am not trying to confuse you, but read the above a couple of times. Some people run a pump at 80% capacity, some at 50% capacity, and some run at 20% capacity. It all depends on how big the fuel lines are and the lateral acceleration.

Here is what I would do for 600HP. This is only an example. I am not saying to use this as what you put in your car. It is only for educational/informational purposes.

600HP * .65#/hr/HP = 390#/hr (assumed .65 because of N20 application)
(N2O theoretically uses a richer AFR)
390#/hr / 6#/gal = 65 gal/hr (middle of the road fuel weight)

65gal/hr * 200% = 65gal/hr * 2 = 130 gal/hr (2x safety margin due to carb)

I used a 200% percent safety margin because of the low PSI carb application.
I would use a 1/2" or -8AN fuel line (I don't like S/S line) for the volume due to the carb low PSI application. I would use a pressure regulator for cooler fuel and stable fuel pressure.

Make sure the pump you buy will flow the GPH at the PSI you run your carb at.
Wait for more people to post and more opinions.

One more thing.

Electric fuel pump GPH also varies with the Battery voltage or what ever voltage you have connected the fuel pump. Manufacturers will say something like 220 GPH at zero PSI and imply MAX. VOLTAGE. If you are not at max. voltage, then the GPH is less, sometimes a lot less.

Overall, you need to find out what GPH the pump you buy puts out at your carb PSI, and your alternator voltage (volts). Sometimes, the voltage from an alternator will drop at high RPM due to firing the coil. This means that your voltage will drop and your GPH will drop because of that. You either need to check what your alternator does for volts at high and low RPM and see if it works for the GPH you need at your PSI.

Or just bump up the safety margin some more.

lol! that's alot to take in. fuel systems are something i'm just getting to understand...and i'm really gonna need to understand them cause i plan on spraying the piss outta this motor and blowing it outta the next motor (15lbs. boost)

OK, so i could actually run something like the holley black pump (120gph@9psi) and be OK...though it'd probably be better with something in the 140gph range. a -8an line will be good...that's good...-10 is expensive, lol! so...will i need a return line off the regulator to the carb? or will one from the n2o soleniod be sufficient?

The 140 GPH Holley sounds like a good choice. And Holley seems to think so to. Check it out:Holley Performance Electric Pumps – Carbureted Products

All that mumbo-jumbo that I wrote.......Holley compressed into a table for their pumps. Check out that link.

As for the pressure regulator, I was thinking only one regulator with the N20 and carb TEEed off it. I have to think about that a bit more.....it might not be the "good enogh".


EDIT: read the fine print from Holley (the asterick * stuff). Notice the talk about lateral Gs, etc. Remember, you are running N20. I was looking at the Holley 12-150 unit

Ooopps, you mentioned boost. A hole new ball game. If you boost 15 PSI at the carb then you are trying to blow the fuel back with 15 PSI. That means you will need to increase the fuel pressure by 15 PSI to keep it at what you had before boost. I think the Holley pump will only do 14 PSI so you will be in the market for a new pump with boost.
Some guys at the www.turbomustang.com board use a mechanical carb pump and put a fitting in it so that the 15PSI of boost will push on the pump diaghram to keep the fuel pressure right. It is called boost referencing the pump. Normally, it is just referenced to free air. Anyway, a new pump will be in order for the boost.

OK, looks like i'm gonna go with the holley black pump and be done with it till i build my next motor...and then i'll completely go through the system and build it up overkill for the blower....

as far as the regulator...how would that work with a return line? where would the return line go?

If you have time and can wait then I would wait to see if someone around here knows of a better pump that has specs like the Holley. I have no idea what the reliability is on the Holley stuff. Someone else might though. Holley might just be re-marking a walbro or what ever pump that you can get cheaper.

It all depends if you need it now or can wait.

no, i can wait...i won't even see the car again until August

Have you considered running a dedicated fuel cell and pump for the nitrous? This will allow you to run higher octane race gas with the nitrous than you have in your tank. It will also save you from having to modify your fuel tank. You can wire the pump to a relay with your solenoids, and can monitor and adjust your fuel pressure independantly from the cars regular fuel pressure.

Not good. The time for a solenoid (N20 & Fuel) is much quicker than the time for the pump to flow fuel (pressure build time). I would at least wire the pump so that it would come on with the solenoids or by a switch in cab. The switch would be the correct way to enegrize the pump, the solenoid wiring would be the fail-safe mode if the driver forgot to switch the pump on.

It would be a wire-ORed connection.

i thought about that, and it might not be a bad idea for now...but i'd rather sump the tank and run two fuel pumps i think for my permanent fix...

if i do what your saying with a dedicated nitrous enrichment fuel system, then my holley blue pump sitting on the shelf in the garage would probably be OK, right? so for a 150shot?

alright, i think that i'm gonna do the fuel enrichment tank deal. anyone got any pics of it this way? my biggest concern is that i can't make it look like a clean install. if i can do a clean install, i'm all over it.

i was thinking of using the JAZ nitrous enrichment tank that holds 1 gal. i'll be putting it in the drivers side battery tray, though i think i'm gonna cut the tray out so it sits down in there a bit better. i'm frickin' obsessed with cleanliness when it comes to installing stuff like nitrous systems, extra wires that wouldn't normally be on the car, etc.

Yes you need the pump to run when you arm the system, not when you activate the solenoids, this won't be very hard to do just run the "on" switch to both relays and let the pump run for a second before you activate the nitrous. The Holley Blue fuel pump will support a huge ammount of nitrous, probably more than you'll end up spraying to the car. I used my windshield washer resevoir as a temporary fuel tank 2 summers ago, I highly wouldn't recommend this but it did work. The Jaz 1 gallon fuel cell would be ideal and can be ran in the engine bay where the battery tray is, or opposite of it. Hiding your wiring shouldn't be a big deal, really the only thing that should show should be the solenoids and the lines. Good luck with your install. PS if you want to see the old setup it's posted as Nutty91RS in the Power Adders, "post pics of your power adder" thread, it's not clean but it did work well, The new install is clean as a whistle but isn't really what you're wanting to do since it runs off of my schrader valve.

If you want to keep any kind of longevity with that motor on a 200 shot, you need to make sure that you are retarding your ignition timing 2 degrees for every 50 shot at the MINIMUM!!!

ooh, good point paul. well, i still haven't gotten any kind of aftermarket ignition system, does the msd digital 6 have provisions for pulling out timing when spraying?

Well, I can't find any listings for a Digital 6 but there is info for the Digital 6 Plus, is that the one that you have?? Because if you do it does have a single stage retard which would work, but it is gonna depend on *how* you have it setup. For example, if you have a single stage nitrous hit of say 200, then you could set the single stage retard to 8 degrees retarded and be done with it. But if you plan on using a nitrous controller and try to *ramp up* the nitrous rate, then it's not gonna work so well.

In the case that you don't have any type of aftermarket ignition control, you cheapest option would probably be an MSD 6A(I prefer the 6AL because of the limiter) and one of MSD's 3 stage retard module. You can buy both of those through Jegs for under $400. Just a note. if you do decide on using an ingition box with a rev lmiter built in or an external unit, make sure that you don't hit the limiter while spraying or some serious crap can come apart. Happy spraying!!!!

oh, i don't have an ignition box at all at the moment, i'm just curious if the cheaper digital box will have provisions for pulling timing, cuase the digital 7 box is expensive!

Hmm, I think that I was editing my previous post when you posted. Take a look at my previous post. I personally prefer MSD, but all the other companies have roughly the same stuff so it's just a matter of what company you want to use vs. price...

i like msd's stuff too, my pops is still running a box he bought in the mid 80's! ok, i'm doing research at jegs.com and i'll be doing research at msd here in a bit. thanks so much guys! i'd like to see this little 305 running high 10's on spray, and ya'll are helping me get there! i love the fact that nobody has told me to just go with the 350 and be done with it.

The digital 6 (plus) box has a twin stage rev limiter, and a single stage timing retard. I believe the only Digital 6 is the Digital 6 plus. 8 degrees timing is on the conservative side I would say you could get away with 6 degrees pulled, but that will depend, what timing do you run now? If you're needing an ignition then the MSD Digital 6 is a good idea, if you already have one then you may want to look into a Digicon smart spark, or an MSD timing controller.

The heart of the Digital-6 Plus Ignition is a 15 Megahertz microcontroller, the fastest of all digital ignitions. What this means is the controller analyzes up to 15,000,000 critical instructions per second! This is over three times the speed of comparable ignitions and produces the most accurate trigger signals, timing and rev limits possible. MSD engineers have spent an endless amount of time testing the components of the Digital-6 Plus to ensure the most efficient and reliable operation. The 6 Plus produces more power with less current draw (20% less) by incorporating an IGBT coil driver that can be controlled for improved coil saturation. Also, power MOSFET technology and high frequency magnetic converters require less input current while producing more energy and voltage. Every spark of the Digital-6 Plus ignition is packed with 135 millijoules of spark energy and up to 535 volts. When used with the MSD Blaster HVC Coil, PN 8252, a spark with over 300 milliamps burns across the plug gap for 400 microseconds. Below 3,300 rpm the Digital-6 Plus produces a series of sparks that glows in the cylinder for up to 20° of crankshaft rotation. This incredible heat ensures combustion to produce great power, quick throttle response, smooth idle and quick starts. To prevent any chance of Electro Magnetic Interference (EMI) a filter circuit is made up of state-of-the-art magnetic suppressor components. This, combined with the more than competent microcontroller, checks and rechecks inputs many times to determine “clean” signals before making any compensations. The magnetic input also features a unique microcontrolled feedback circuit for total EMI-free operation. CARB legal in all 50-states via EO #D-40-31.

Digital-6 Plus Ignition
121-6520
MSD's Digital-6 Plus lets you switch between two 100 rpm increment rotary-switch adjusted rev limits. A single stage retard is provided for nitrous and top end performance while a start retard eases pressure in the starter, flywheel and engine. An adjustable magnetic trigger signals while an LED display warns of trigger signal problems or faulty charging systems. Fully potted with polyurethane for vibration and water protection.


--------------------------------------------------------------------------------

Operating Specifics
Operating Voltage: 12-18 Volts, neg. ground (Full voltage output down 7 volts supply)
Current Draw: 0.7 Amp per 1,000 RPM (7.2 amp) with 14V bat.@ 10,000 RPM
RPM Range: 12,500 RPM with 14.4 volt suppy
Spark Duration: 20° crankshaft rotation thru 3,300 RPM
Spark Energy: 135 milliJoules per spark
Weight and Size:3.7 lbs, 8.5''L x 4.5''W x 2.2''H
Voltage Output Max:Primary: 535 Volts delivered to coil
Secondary: 45,000 Volts (MSD HVC Coil)

and it's only $299.99 from jegs!
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no ignition box in the car currently. and won't i have to run a different distributor? i'm currently running a stock HEI with an incap coil.

18* initial, 36* total all in by 3000rpm.

I run the MSD 6 in my car with a Holley Laser Coil (same coil as MSD different package) but would highly not recommend running a rev limiter with the nitrous. I've seen friends cars hit the rev limiter on the nitro and cause some nasty backfires, I myself have overshifted my car into neutral and over revved it but it didn't back fire, if it had I probably would be out a MAF meter. The ultimate setup would be the MSD window switch to avoid any over revving and rev limiting on spray. Another thing to keep in mind is to keep the plugs a stage or 2 colder, and gap them from 35 to 40, not the mSD recommended 50. Your timing should be ok with 6 degrees pulled, if you pick up any detonation go back another 2, 1 degree of timing makes a noticeable difference on nitrous, I've seen this personally using the digicon to fine tune my on spray timing curves.
P.S. mw66nova I just copied your setup for true duals from long tubes and I couldn't be happier with the results, thanks for providing the part numbers etc.

the digital 6 box looks like an incredible deal. what if i just ran the rev limiter way up (like around 8000rpm...shift points are 6k, i've never seen more than 7200rpm by accidently going into neutral, i normally react to it pretty quickly) when i'm running nitrous. it's gonna be cheaper than a 6A and retard box...and it's got a 2-step built in which would be great for burnouts.

i'm glad your happy with the exhaust system, it's a cheap efficient way to run a very good flowing exhaust system WITHOUT sacrificing too much ground clearance.

Well, it depends on how you have your nitrous setup to activate. Do you have it set to a button that you have to press in order to spray, or is it set up to a full throttle microswitch? Also, is your engine set up to rev that high? Nitrous likes to make the engine rev, so it can be dangerous territory if you aren't ready for it. If you are using a full throttle microswitch, then some type of window switch would honestly be the better option. This way, you can arm the system, and set the window switch to turn off at 2500 RPM and off at whatever RPM you want. You might even set the initial window RPM higher to suit your traction needs, but as long as it isn't set lower than 2500 RPM you'll be fine. With a window switch, your run would go something like this....

1. Stage 1 retard for the burnout

2. Pre stage, staged, nitrous system armed, window switch set for 3000 RPM

3. You launch, probably at WOT, at 3000 RPM nitous kicks in full

4. Nitrous pulls all the way up to the window limit(5700 RPM) and you shift at 6000 RPM

5. Grab the next gear, engine RPM's drop slightly(below the 5700 RPM limit) and as soon as you get back into WOT, nitrous kicks in full again.

It will take some time to get everything setup the way you want with all the shift points but it is by far the safest method. I mean, you COULD set you rev limiter to some astronomical amount, but it's noit going to do you any good. The whole purpose of having a rev limiter is to keep the engine from overrevving so it doesn't damage itself.

the car is an automatic, if that makes any difference, and the converter flashes to 4000rpm at WOT. i would use a WOT microswitch on the carb. (i haven't bought anything yet.)

Well then that is better in a way. With you using an auto, the trans will shift by itself so I would set your rev limiter to say 6200(cause you said that it would shift at 6000) and still use the window switch for the nitrous activation and have it shut off at 6000. This way, if something lets go on a pass, then the engine will rev up to 6200, and hit the limiter but the nitrous would have been turned off 200 RPM eariler.....

i see what your saying now...where can i get this said window switch and what is it wired into?

Having the rev limiter that close to when the nitrous goes off is risky risky buisness there's still going to be nitrous running through the engine for a moment, and if the transmission slips, or the reaction is a little off then there's a good chance you'll get a hood ripping backfire out of it. Simple solution is to set the rev limiter a little higher, like 7100rpm just to be on the safe side. As for the 4k stall you'll be fine with it, guys with bigger stalls like that usually stage up and spray right out of the hole. I honestly have never watched my tach when I spray my stock motor, as soon as I feel it's good and gripped up I spray it, that's usually around 2300rpm. The whole point of "never spray below X rpm" is just to keep you from spraying while the engine's lugging and getting a big nasty nitrous backfire. As soon as your motor is pulling and not lugging spray it, which with your gears and stall will probably be immediatly off the line. On shifting, if you have a solid automatic spray through the shifts, you'll save yourself quite a bit of time this way. I built my TH350 to hold 650lbs of torque just for this purpose, I've sprayed stock 700R4's through the shifts and never had anything catastrophic happen. You may want to download and read a few manuals from The Nitrous Works, NOS, and Nitrous Express, there's alot of good solid info and wiring schematics in there. The way I have my setup wired is to a button, no full throttle switch, no window switch, just an arming switch and a momentary switch ran to the relay then to the solenoids. I don't usually mess with the full throttle switches unless the nitrous is going on a manual car that will have to have the nitrous shut off between the shifts (unless the person shifting is real ballsy). As for the window switch, it's great for safety and consistency but isn't necassary in all reality, just a nice peice of equipment to have, I'm pretty sure you will be able to manage the nitrous with just an arming and momentary switch and it will give you a little more control of when the juice goes on and off. I'm really hoping you get that 10.99 out of this car, that'll be bragging rights for every third gen owner on the planet!

the 700r4 that's in the car will hold the power...i'd still like to run a WOT microswitch, that way if i lift, it'll turn off. i don't see a reason to run it on a momentary on switch say on my steering wheel...either my finger pushes it or my foot does, i don't think it'll make a difference honestly...and i like the microswitch better.

just my opinion, but the microswitch is the best. And you really do need some kind of ignition upgrade i would say. A MSD 6a or MSD HEI distributor or something. But you dont need the rpm switch or anything unless you just have money to blow or you have a manual trans it would come in handy.

well, i like the digital 6 plus that will pull timing out and has a limiter for burnouts and stuff. i'm looking at it for more than just the engine rpm limiter. and it's not that expensive, it's only like $299, though i'll need to put in a new MSD distributor too to run that box. looks like i'll be dropping about $500 or so on ignition before i even look at upgrading my fuel system to put nitrous on it, lol! it'll be the end of the year or early next before i get it done...

Trust me you will love a better ignition system, i went from a stock HEI with an Accel coil and a curve kit, to a MSD Pro Billet HEI, and it is night and day difference, but the most noticable is the smoothness, and it is smooth up to (or maybe more) 7000 rpms

i know my combo is already impressive, but i've still got alot left in her. it's got a stock ignition system in it. most of the bushings in it are stock rubber bushings still, it's got junk shocks/springs...etc. there is alot left on the table yet and i can't wait to get home and really start tweakin'. i KNOW it'll run 11's n/a.

i run a one gallon jaz cell with a holley blue pump. Works great

do you buy chance have any pics of the setup?

You don't need a MSD dist. to run the digital 6 plus box. You can use your HEI. In fact with a CD ing. box like the MSD, the dist. is only a trigger.

You take the module out of the HEI, and wire the box up to the HEI's pickup.