12 replies to this topic

[lemons]

How would that work out? Just a question......

[Vandemar]

You could either spray it before the venturis (probably a bad idea), behind the air filters, or use a direct-port setup tapped into each runner of the intake manifold. None of the off-the-shelf single nozzle systems would work, because there's no one point that you could spray it at to get all 4 cylinders.

[rexsk8er]

Well i posted on the other topic you put up before i realized you had this one. Just the way i allwasy understood it......

They have different types of nitros systems fogger, direct port, wet system, dry system.... Foggers spray into your intake and are consided a wet system. Dry systems inject the nos into your fuel supply. Direct port injects it directly into the ports at your head.


Tthe way carbs work is on a vacume because of a venutri. Nos will increase the engines rpm and fuel needs and it will automatically compensate for an increase in fuel needs because of an increase in flow through the venturi causing a larger vacume. That is if you have the right jet size. Carbs work exponentally, basically if you have a carb that can create a flow rate for a certian engine fron 1000 rpm to 5000 rpm, as long as the fuel needs are in a relitivly liner fashion its flow can increase exponentally at the linier rate the jet allows. The reasons we need to tune jets is to modify the fuel curve so that it can be as close as possible to the needs of the motor. If a carb couldnt compensate for extra air ect ect ect, than it would have to have many jets instead of 2 one for idle and one for high speed. You will have to rejet your carb however, which will decrease fuel economy, because the fuel needs of the motor will be changed, but it will still run ok w/o nos. Thats why so many old schoolers love nos because its so easy with carbs. But it is a good way to blow your motor. The thing that kills motors is hp and torque, not power adders like nos and boost. They contribute to it, but as long as you run a low amount and do jet the carbs right you should be ok. Say a 50 shot or somewhere in there.



Sean

Edited by rexsk8er, 04 January 2005 - 11:19 AM.

[Vandemar]

Nos will increase the engines rpm and fuel needs and it will automatically compensate for an increase in fuel needs because of an increase in flow through the venturi causing a larger vacume.

Nope. That might work for a supercharger or turbo at low boost, but if you're spraying nitrous into a carbed car, it needs to get fuel from somewhere, and there's no way for the carbs to "know" that the gas (air/nitrous mix, not fuel) has more oxygen in it than it's supposed to, and fuel needs to be added to make up for it. Unlike other power adders, nitrous works by adding an accelerant that contains a higher percentage of oxygen into the engine, instead of just cramming more air at 21% or whatever oxygen content into the motor.

You will have to rejet your carb however, which will decrease fuel economy, because the fuel needs of the motor will be changed, but it will still run ok w/o nos.

Wait, so you're telling him to jet the fuel system like it's spraying a dry 50 shot all the time ? On an engine that makes ~100hp on motor, that's 50% more fuel than it needs, which gives you an A/F ratio of around 10:1 (or lower). On Mikunis, the main jetting system handles everything over 20% throttle, and having that much extra fuel that much of the time will wash all the oil off the cylinder walls, clog your cat (if you have one), along with the fuel economy issues.

The reason nitrous is so easy with domestic carbed setups is mostly thanks to plates- they use a spacer that goes under a 4bbl carburetor that holds horizontal bars with holes in them that spray nitrous & fuel into the intake manifold (bypassing the venturis & carb entirely). That's not really an option with Mikunis, so a direct-port system (which, BTW, is still in the intake manifold, just closer to the head) is pretty much the only way to do it.

[criticalmass]

http://us.f2.yahoofs...hrTy2BBHlTTqvmU

for a 510, but you get the idea...

[jonesy]

Link no workie....


jonesy

[rexsk8er]

Ehh i dont know alot about nitros systems..... i was just takeing from what i know(wich is more about forced induction). sorry to missinform, but i suppose your right Vandemar...... learn somethin every day

[lemons]

Vandemar knows his stuff. I did more research too, if you rammed more air through carbs (to my knowledge) via a ram air induction setup, you would effectively get more power at speed. However since nitrous has a higher density, you'd mess up your fuel mixture and melt you pistons to the cylinder wall.

Another reason nitrous is used is because it also can help prevent detonation. Let me explain, the two extra nitrogen atoms absorb heat helping to prevent detonation, now granted… if your fuel mixture is too lean or your timing is advanced too much… KABOOM

Nitrous is just as safe as a N/A car, if not safer. With nitrous your motor is only pushed when you have the throttle mashed and the nitrous armed.

Just a few things I learned.

Edited by lemons, 05 January 2005 - 10:48 AM.

[Steve91]

How would that work out? Just a question......

<{POST_SNAPBACK}>

If your planning on doing NOS on side drafts, I highly recommend you do a 4 fogger system plummed directly into the manifold runners. I've done this on several inline 4 motors and it works great.

[lemons]

How big should I go on a 140k miles motor? 50? 80? Isnt someone on here using a 100 shot on with a Holley 750DP Carb?

Edited by lemons, 10 January 2005 - 08:24 AM.

[eldo]

Always start with a 50 shot until you learn to read what the motor is doing. With a 50 shot, you won't have to retard the timing and even if something does goes wrong (Leaning out,etc.) , the worst that will happen will be melted plugs. When you have the 50 shot tuned and running right (You'll enjoy that rush for a while- 50 shot with a cam,headers and everything else stock could get you high 14's), then go up in jet sizes. Anything larger then a 50 shot will require higher octane fuel, retarded timing (4 degrees at first and then bring it back up 1 degree at a time -Standard setting is 2 degrees retard for every 50 shot but will vary pending on compression, cam overlap, etc..)I would also run another dedicated fuel pump for the nitrous system. Learn and have fun!

Ed

[criticalmass]

hmmm, works ok for me...??

[4dr]

How would that work out? Just a question......

<{POST_SNAPBACK}>

If your planning on doing NOS on side drafts, I highly recommend you do a 4 fogger system plummed directly into the manifold runners. I've done this on several inline 4 motors and it works great.

<{POST_SNAPBACK}>

this makes the most sence to me. im pondering the thought of nitrous and side drafts on my d15b build. one idea im possibly thinking of is using an OEM intake manifold (which has 4 spots for injectors) to be used for the nitrous taps since youd be leaving those holes free with the addition of some nice side drafts

.. just a random idea. have to say this is a nice thread, i have had one similiar over on my website i posted but there isnt as much interest due to most of the people sticking with pgmfi for the 88+ cars.

great idea with a carbs only forum!