Nitrous delivery question...

[blk00gtvert]

I am more or less in the process of designing a nitrous delivery plate for a certain car. I am currently studying other companies plates and came up with a question. on spray bar setups, what kind of line do they use for the spray bar. it seems they use brass. i was wondering why they dont use stainless steel. will somthing like 1/8 stainless break line be effective? it has to stand up to the pressures of a break system which surly exceed that of which a nitrous system sees (1,200 PSI max). do they use it to keep cost down or is there somthing i am mimssing. also. assuming your supply is from one end and you have tiny holes along the bar, would one run into a distrobution problem? most companies only feed from one end but that is only going across 4 inches of carb or so. i will be crossing 6-8 inches. same question applies to the fuel bar... thank you for any advice you have. sorry for so many questions

 

[bvanhiel]

I have no first hand knowledge, but I would imagine it's because it's easier to drill many small holes in brass than stainless.

-b

 

[blk00gtvert]

wow fast response.. thank you. i indeed thought this as well. Just seems like stainless would be better than brass.

keep in mind that nitrous is somwhere around 192 below zero when it exits. does brass had any benifits at these temps?

 

[patprimmer]

It will be because it is a lot easier to drill holes to precise diameters in in the precise location in brass.

Regards

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[blk00gtvert]

any info on the delivery methode?

 

[jbthiel]

what is your expected HP boost? If you are adding a reasonable amount of nitrous, especially in the plenum area, a single side feed shouldn't be problematic considering the pressure that you have available. Are you trying to put this inside of a Chev TPI or Ford 5.0 manifold?

 

[blk00gtvert]

I am working on a nitrous plate the fits between the supercharger and the intake of a ford lightning. it will surve two purposes. one inject nitrous but also it will be directly spraying the intercooler inside the intake. it will i am guessing nitrous amount between 75-250... with most people running 75-100 thank you

 

[jbthiel]

I would just suggest taking it a step at a time and read your plugs for good distribution. Its easier than replacing the pistons Just curious, are you putting in bigger fuel injectors or adding fuel through the plate?

Have fun.

 

[blk00gtvert]

i plan on making two. a dry plate and a wet plate.
that is why i had my question about having a second bar for fuel above the nitrous bar. at lease that is what i THINK other companies do

 

[jbthiel]

I couldn't say for sure, but I think the gas goes in above the nitrous. That way the expanding nitrous helps to atomize the fuel.

Also, make sure the nitrous holes aren't pointing towards the throttle

 

[mattsooty]

I have no experience of Nitrous 'best practice' but surely the expanding gas will be cooling the charge and therefore inhibiting atomisation?

MS

 

[Majik]

Not if your shooting fuel with 1200psi of escaping gas. I don't like spray bar setups though. Fogger nozzles would work fine per runner but this is a pretty small shot. The only problem I see with this setup is that he's keeping the stock lightning intercooler which is going to seperate the gas from the nitrous and with one backfire that manifold is going through the hood. Tunning issues and gas puddling in the manifold asside. Second no one here has addressed how much flow vs how many holes and of what size to assure optimal distribution across the bar. Since you are making this yourself you also don't know how to jet it since your bar will not be the same as say a holly 650 spray bar kit. So the jets that work for one kit will not necissarily work for another. I would just buy a bar kit that's close to the size you need then take the spray bars out of it and put it in a custom enclosure unless you feel the need to fabricate everything.

 

[blk00gtvert]

i see your concern but how is injecting the nitrous onto the manifold any differnt than the thousands of people that inject the nitrous and fuel via a single nozzle all the way back into the air intake. wouldn't that have MORE of a chance of puddleing due to the fact that the fuel has longer to drop out of suspension? i am not arguing i just want to see if i am missing somthing here.

you bring up a very good point about the hole as size of them. is there any way short of just experimenting with it on my engine?

 

[patprimmer]

I would make sure the total cross sectional area of the jets is less than half (I would think even as low as 1/4) the cross sectional area of the bar.

I would drill very slowly with a sharp drill to minimise burs inside the bar.

I would try to have some sort of snug fitting mandrel inside the bar as I drilled, or I would try to have a device to remove the burs, like maybe a long series drill the same dia as the inside bore of the bar.

You could test by flowing water through it and measuring the output from various jets by collecting into individual containers.

It would offer some advantage if you inject the nitrous and the fuel downstream from the inter-cooler as the inter-cooler will remove more heat from the hotter charge which can then be further cooled by the nitrous.

You will need to do something to the fuel enrichment system to correct for manifold pressure as the manifold pressure will be a bigger fraction of the fuel pressure than it is of the nitrous pressure.

Do you know what cross sectional area of nitrous vs fuel enrichment is required.

Do you have or can you get or borrow various commercially available systems so you can count and measure holes and compare them to performance. You might need to do this in a pressure regulated chamber to replicate manifold pressure.


Regards

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[blk00gtvert]

thank you very much. i am pretty sure i will be able to keep burrs to a min so i am not concerned about that.

injecting below the is pretty much out of the question without resorting to a direct port nitrous setup which would defeat the purpose of me desinging the plate.. trust i have tried and it is just not workable.

please explain further about the fuel enrichment. are you talking about how the fuel pressure will stay the same but the boost will increas thus lowering the output of the fuel? being as that it is a roots style system, when you go WOT the boost is instant and it stays there. I was thinking that i could use this to my advantage. tuning my jet to be 11.5-12.0 when the boost is on. and when you go WOT at first the boost will take a second and the system will rich untill the boot catchs up thus eliminating the lean condition that wet kits are known for. maybe i am wrong?

thank you for your time

 

[patprimmer]

So long as you have constant boost when injecting, and tune to that boost, it won't be a problem. I was thinking other types of non positive displacement blowers as inter-coolers are not all that common on roots blower systems..

Regards

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[blk00gtvert]

thank you again.
the pain here will be if i plan on marketing this kit i will have to have a jet chart for every possible boost level can you think of any other way. i thought of an FMU but that will mess with the factory tune. and the sole purpose of poeple buying wet kits is they dont have to get tunes for them. i may have to just sell them as a dry kit if i cant figure somthing out.

 

[Majik]

Well kinda the way I see it is that a nitrous jet acts as a restrictor to the system and lets only a limited ammount through said orrifice. But I've also seen that the jet sizes for fogger nozzles don't transfer to spray bar setups. Hence why I'd just go for the disassembly of a current spray bar unit and modification so I'd be sure I had the correct jetting. Keep in mind that fogger nozzles use the nitrous to attomize the gas in the nozzles. I believe the current though is that you need an open plenup area for a spray bar unit. Are you looking to make a super stealthy install?

 

[blk00gtvert]

a stealthy install would be nice but not needed... i am going to run the bar from front to back so it would be nice to have the option of putting the lines and solenoids in the front for looks or back for stealth.

 

[patprimmer]

If you can adjust fuel pressure to increase by the same amount as the boost, but have nitrous pressure constant, it should work.

To do that you will need a high pressure fuel pump and a manifold pressure sensitive fuel pressure regulator.

I believe this is common with turbo setups and normally involves a spring and diaphragm controlled valve as the pressure regulator with a fitting to plumb manifold pressure in over the diaphragm to assist the spring.

Regards

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Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.