signsbyrick

I am building a 350 nitrous motor. I am having problems with the pistons everyone says I have to run a flat top piston. Is that true or can I run a dome top piston.

Thanks
Rick

bjuice

No you can run a dome piston with NOS.. ( broad answer here)
...but of course as you know there is a-lot more to this story in building a proper Nos Motor other than just pistons...

if you need more info..let us know..there are guys on here that can tell you from the piston's,proper cam selection, fuel delivery, proper timing extraction etc........

thanks brian

signsbyrick

Thanks but I do need to know more lol can you guys give me some pointers on running NOS on a 350 chevy.

Thanks

bjuice

ok i will assume you are gonna run a decent shot of say 200/250..here is what i would build for myself and have seen built as TRUE 100% NOS motor

1- good bottom end. 4340 crank, aluminum rods is best,"cushion"
the impact of the NOS hit therefore more forgiving on bearings.
forged pistons..make sure the ring gaps are set up for a spray motor, ed with edvance engines or TOM 'head Mod" can get more into detail with this.

2- you must get the proper cam profile, that will have a longer duration..the principle is the same as a blower motor camshaft..the more you pack in a motor the quicker is has to get out.. the exhaust valves have to stay open longer in order to get the exhaust out So the lobe seperation will be greater....they make cams just for NOS...BE ADVISED THIS CAM WILL BE A SLUGGISH DOG UNTIL YOU PULL THE TRIGGER ON IT (NOS)

3- you CAN use domed pistons..normally NOS motor is not the extra high compression motors but you can have your engine guy work your chambers of your heads to accomodate whatever needs you have here for the CR

4- you will need to run a much COOLER plug..normally 3 steps cooler than your normal heat range plug,..and be sure to close up the gap..say 25 thousandths or so,,give or take.

5- make sure you have VERY ADEQUATE fuel system..a prostar 500 magnafuel is a good source to operate THE NOS AND MOTOR TOGETHER..DO NOT,I SAY DO NOT..try to run the motor and nos system together on one lower production fuel pump such as a holley blue etc...if you use a holley blue or black or something equal to this then..you must run a dedicated fuel system to feed the nos side and one to the motor side..the reason is if your fuel pump cannot keep up with the demands of the nos and motor it will lean out your motor and burn it up....so keep a healthy fuel supply to the nos and motor..

6- be sure to TAKE OUT the proper timing from your final timing once nos is activated,,NOS recommends 2 degrees of timing per 50hp of NOS...so a 200 shot would need a minimal amout of 8 degrees of total timing retarded,
Nos is to be activated at WOT only ..so you can buy the throttle activated switch to when you go WOT the nos will activate. you can also buy the adjustable box that will tie in with the throttle micro- switch so that when you activate the NOS at WOT you also retard your timing,,you can buy extra chips to take out however much timing you need to...you can buy you a HOBB switch to up your insurance on fuel saftey for the NOS..all it is is a fuel saftey switch that you wire in line with your NOS fuel side..the switch has a internally 4 lbs presett to where it will cut off your NOS if the fuel pressure drops below 4 lbsi

7- you will need the proper TQ converter for NOS..normally its a tighter converter... Loose HP converter is no good with NOS,,,You will drive right thru it...

8- you will also need to make the proper gear changes in your rear end...it will take a higher gear with NOS over what a raw HP MOTOR would take to run.




This is the high points,,,there is plenty of more info..but as you can see already there is much to running a TRUE 100% NOS motor,,,you will also be very dissatisfied with how a TRUE NOS motor runs on Motor only...its sluggish, heavy feeling, will NOT TURN UP for nothing...BUT WHEN YOU PULL THE TRIGGER OR THOSE TRIGGERS...IT'S LIKE A BEAST COMING TO LIFE...
here is an example of my friends all out 100% NOS MOTOR PASS WITH AND WITHOUT THE NOS....SEE HOW IT COMES ALIVE


1/8 Mile et on motor only- 7.16 at 102 mph.
1/8 mile et on 300 shot 'progressive"- 5.60 at 135 mph...


so that is my take on it...


thanks brian

etbird

What Brian Said.

thetanman101

Word.

pdq

If you’re running a carb, I’d think about using a carb built for nitrous. Besides the points that bjuice touched on I think the carb is often an overlooked part of building an engine for nitrous. With the proper tune up nitrous will make more power and some serious heat which of course attracts the dreaded detonation monster. Due to the increase in fuel needed for n2o you’ll need to speed up the burn rate via ignition timing events etc. and a professional built nitrous carb which is fitted with a custom fuel/nitrous curve. (Better fuel atomization, even fuel distribution and detonation eliminating signals to help keep you from lean conditions). Don’t let anyone tell you there is no difference in carbs or no such thing as a nitrous carb. Just ask the big dogs.

Also, I’m not trying to butt heads with bjuice (I agree with all his points) or anyone else for that matter, but when selecting a cam you might want to try thinking outside the box and do some research on using a cam with tighter LSA. With today’s cylinder head technology and the exceptional work some of the cylinder head gurus are producing it may be of an advantage to delay the intake opening and delay the exhaust opening without changing the exhaust closing point. (tighter LSA) What’s the advantage? Here’s what one of the big dogs has to say. Pay close attention.

Patrick Budd from ProCar explains it this way: (if using a PG)
“The solution may lie in providing the engine with more ability to accelerate via shorter timing events, helping it pull up and away from the shift on its own. A slightly tighter LSA (removing the duration from the exhaust opening pulls the centers slightly closer- we have no beef with the exhaust closing point) will also set up a hard accelerating engine through the upper- midrange. The last thing a nitrous fed engine wants to do is sit at a steady state, and anything we can do to help it accelerate up from the rpm drop on the 1-2 will pay off in et and reliability.
By trimming timing events to the minimum, we’ve arrived with a combination that runs harder, more predictable, and with greater reliability.”

Think about it! This nitrous stuff isn’t rocket science but it’s not a walk in the park either. When using nitrous its important knowing what you don’t know or it can become costly due to lack of knowledge. I do hope Tom or Ed or Curtis will chime in when time allows.
Good luck,
John

bjuice

I AGREE on the CARB theroy...just like Blowers.....Any power adder would require some type of tweaking on the carb..

Brian