nitrous fuel pump

[imean340]

Hey everyone. Just wondering what fuel pump you guys would use for a 125-150 shot on a 340 (forged pistons, don't worry )

I may buy a NOS adjustable powershot kit but im not sure if my current pump will be sufficient. Im not sure what kind of pump it is but im fairly sure it's OEM (owner replaced it shortly before I bought the car...never told me what kind but it's been working fine for my 340 with .480 lift cam 230 duration,J heads and a 670cfm holley). Figure I could order the pump with the nitrous parts all at once if it'll be necessary. thanks!

[MEK-Dangerfield]

You are out of my league.     This should be an interesting thread.   


   Mike

[imean340]

I hope it gets interesting! Want to order this stuff soon as i'll be putting the new tranny from Tactrans in along with a protorque 9" converter. Don't plan on using the spray much at all but i'd really like to get this car into the high 11's some how and im thinking spray is the way (cheapest way right now at least).

Im thinking of just trying a 100 shot, back the timing off 4* manually so I don't need to buy a retard box, going 1 heat range colder on the plugs and just keep an eye on fuel pressure when spraying the 100 shot. Of course im going to run a fuel pressure safety switch so if something does happen, the N2O will shut off and I should see the drop in fuel pressure on the gauge. If all works fine then I save myself money on a pump....unless somebody knows for a fact that it flat out wont be sufficient which in that case i'll just order a better pump with the nitrous stuff.

[Moparal]

Most people run a seperate line and it's own pump. You'd be safe running like a holley red. It is set to 7psi. And you could run a pressure cut off switch. The shot your thinking about doing isn't all that much. I had ole mopar buddies that played with the stuff. They ran msd but kept the plug gaps at .035  Said the plug tip burns off before burning the piston. A 150 shot is about like running a stroker kit in the mild form, so don't expect all that much. I am no pro at it tho.  I did have friends in it tho that were serious with it and ran in the 7's 8's and 9's.  When you play, you pay. Parts aren't cheap

[imean340]

I have some experience with nitrous but mainly on fuel injected chevies . I've seen as much as 8 or so tenths from a "125 shot" and almost a a full second from a "150 shot" when the traction is there on 350 LT1's (mid 90's GM motor before the LT1). Installed small 50-70 shots on imports as well and I have seen good results.  Figured i'd get similar results from the challenger. Not looking for anything crazy, just want a cheaper way of dropping 8 tenths to a second vs. doing a whole new top end.

[Moparal]

What you said is what I figured.  Not much.  Is that going to be enough for todays street actions? Nope. But it will be fun

[71chally416]

You'll hear 100 different suggestions on what to do with a Nitrous fuel system, and we all know somebody (most likely a few people) that either lifted a head or screwed their motor up using it. First off get it out of your head that a stock fuel pump is adequate for either a built motor OR a motor using the hose, and forget what the instructions in the kit say. A stock fuel pump and line are barely adequate for a stock motor, let alone one making 125 more HP. If you have a pump and fuel line that can handle the motor at the level it will be at when the system is on, then my advice is to plumb a seperate line for the hose with a small fuel cell in the trunk that has racing gas with a seperate pump. I know that sounds like overkill, but if you ever look at the cars going fast consistently using it that don't hurt parts all the time, that's what they use. It only takes a few seconds to screw a motor up if a hosed motor goes lean and turns into an acetelene torch, so it's a good investment and it's the way to get the absolute most from it. 

[Chryco Psycho]

 
 you need at least 1/3 more fuel than stock overkill willnot hurt + a seperate fuel system is ideal

[tactransman]

Kris,I ran NOs on my Chally in the older days. I would go with this pump http://store.summitracing.com/partdetail.asp?part=MAA-4110&FROM=MG it is a quieter electric and run a seperate regulator for the NOs mixture adjustment. If you do not go lean,you will be fine.

I recommend a low fuel pressure cut off switch. http://store.summitracing.com/partdetail.asp?autofilter=1&part=NOS-15750NOS&N=700+115&autoview=sku


The Sniper system is a good adjustable system.http://store.summitracing.com/partdetail.asp?autofilter=1&part=NOS-07001NOS&N=700+115&autoview=sku

My car ran 11.80's on the juice. 

[imean340]

71Chally, I don't know the specs of the stock fuel pump but it may not be stock---all I know is I can take the motor up to 6500rpm without a dip in fuel pressure at all. The pump was painted over when I bought the car, I could try to check the serial numbers on it and see whats up but i'll likely just replace it if theres any risk so long as the N2O doesn't get too expensive...then i'll just ditch the idea for now.

The cell idea is ideal for spray, I agree.  I would go that route if I had more $$$ to  spend but im just trying to look for a cheaper alternative being that im only using a small shot (maybe as little as 100-125 if I see the times I want). As Terry mentioned, im going to run a fuel pressure safety switch so I shouldn't have any serious issues of running out of fuel to the point of grenading. Of course, im still very thorough with nitrous and i'll be checking all the plugs probably 10 times before actually running a full run down the track all out. If it's even a little lean, i'm fairly sure I could catch it before it does any damage. I'll probably start with a 100 shot jetting, on the rich side with conservative timing retard and see how that turns out. When I get the timing/jetting worked out perfect on pump gas--assuming the fuel pump is adequate-- i'll probably mix some race gas in the tank just for insurance whenever using the spray.

Terry, thanks...i'll keep that in mind. The sniper system looks nice, I must say...great price too! Do you think there's any mechanically driven pump I could use though that will be enough? I know some of the holly pumps and the eddy performer rpm pump flow upwards of 110gph. The eddy rpm claims to support 600hp, I should only be pushing maybe 500hp on spray. Eventually I'd love to just go through the fuel system and do it from back to front with a cell, electric pump and braided lines maybe when I have more cam/more heads but for now im just looking for the cheapest/easiest way to safely run a small shot. Still have a lot of small things to fix and not a lot of time to work on the car so bolting on a new mechanical pump would surely be cheaper and easier for me right now.

[71chally416]

The key is will it be adequate with another 125hp?? All the nitrous jetting that comes in kits is safely on the rich side. You could get away with a good electric pump and a big fuel line all the way into the tank. 1/2" is best, and make damn sure the pickup in the tank doesn't get uncovered (have enough gas in the tank!!) along with the pressure switch. That would be the minimum I could ever recommend. Mechanical pumps are inadequate and it's always better to push the gas from the back instead of pull it from the front. If you can afford to fill that nitrous tank all the time, you can afford a good pump and fuel line too. And the second you ever feel the car nose over, get off of it. Running out of nitrous can be just as damaging as running it lean. The excess gas will get trapped between the 1st and 2nd rings and hydraulic the top ring lands in the pistons. That's why pro built nitrous motors have a groove machined in between the rings, so that excess gas has somewhere to go.

The cars using the big systems like the Fogger also have the top part of the piston machined smaller than normal because they will expand more with Nitrous use, and they use special tool steel rings with wider than normal gaps, but that's another story.

[imean340]

Thanks for the advice 71chally. I'll see what budget I have to work with and figure out if I can make this nitrous thing happen or not with a new pump and fuel line. might have to ditch the idea for now but maybe if I get some good deals on parts I can move forward. I see what you're saying about going rich when n20 shuts off and I have also seen a few motors that had butted rings due to too tight of a ring gap. Figured the latter wouldn't be a problem with such a small shot though, I mean I have known guys who have ran 100 shots in stock gen 2 SBC's for years just with the proper fuel system/ignition system mods. I don't plan on using the nitrous much at all...I can only make it to the track maybe once or twice a year and I might use the nitrous just for fun/testing maybe a few times on an open highway at night or something but overall  i'd venture to say i'd try to limit its use to maybe 10 or 15 runs a year...certainly not something im going to be using on a weekly or even monthly basis. When I DO use it, i'll make certain I have enough spray in the bottle and enough fuel in the tank. As I mentioned, eventually i'd love to either sump the tank or put a fuel cell in the car and do a really wicked fuel system but I don't have the $$$ right now so I don't want to do anything thats not necessary. It's sort of a want-to-be race car,  it's got 4.56's, big tires, eagle forged I beam rods, speed pro forged pistons, 70/30 and 50/50 drag shocks but at the heart it's just a mild cammed 344 making maybe 400hp if that....nothing crazy. Trying not to go overkill because eventually i'd like to build a meaner motor so I don't want to spend too much now on something that I may have to change a few years down the road. Not to mention there's only so much I CAN spend lol

[71chally416]

If the chevys have FI they already have a much better fuel pump than you do. Most any FI car can get away with the stock system up to a certain point because they have a high pressure pump in the fuel tank.
Some even use the dry Nitrous systems that just inject the nitrous and increase the fuel pressure to the injectors when it's on to compensate for the needed fuel. Apples>Oranges.

[imean340]

True, but the high pressure pump is still only there to feed the injectors that require high pressure. Not like they intend those pumps for being used for an additional 100hp either. I wasn't trying to compare fuel system though, I was using it as more of an example for the bottom end, from what i've seen the 2 bolt main mopar bottom ends seem a little stouter than a 2 bolt main chevy.
Here is my idea right now...

I could buy my friends 1/2" sending unit for cheap, run 1/2" line up to the mechanical pump and use either a 110gph pump if I keep the shot to maybe a 100hp shot or a 130gph pump with a fuel pressure regulator if I want to run more. It would seem like the 110gph performer RPM mechanical pump should be more than enough for at least a 125 shot, it claims to support 600hp and even though N2O will require a little more fuel than all motor for safety, that's still probably 100hp more than i'd be making on spray. I'll run a fuel pressure safety switch maybe with a light running off the out side of the switch so if it does shut the system off due to low fuel pressure, i'll know right away when the light goes out. If I really do some shopping i'm thinking I could MAYBE pull the whole setup off for 650. What do you guys think? 650 is already 150 over my budget but i'd work some overtime...I can't really go any higher than that though.

[71chally416]

In the bottom end there's no comparison. It doesn't matter how many bolts they put in Chevy caps because they're small bolts and the caps are about half the size of a 340's. The Chrysler rods are way stronger too. It's the pistons and rings that will get hurt. If you have some miles on the motor the gaps shouldn't be an issue if you never go lean and you keep the shot small.

What you describe sounds OK. The stock fuel line and pickups are just not adequate. I just prefer electric because they don't heat the fuel up with engine heat, they save a little HP and are cheaper than a good mechanical. They are a pain to install though.