For whatever its worth, I sprayed a single .102 jet in my LLY both on the sbe and built engine. It took 4 tenths off my ET
Question: Built Motor & Trans How Much NOS Can it Safely Take
- Thread starter prostreeter600
- Start date
Kind of a loaded question. I've run .036 jet on the dyno and it is good for 100hp when fuel only is in the 1200hp range. If running 100 psi of boost at 1200hp, the results of N2O will not be the same if pushing 60psi of boost and 800hp.
If you are on a stock crank shaft, you are already at, or over, what it can take. Adding a big shot to it will break it. If your drive psi is already up in the 100's on fuel, adding a big shot will not get you 300+HP unless you waste-gate the turbos.
Higher RPM (over 4500 rpm) will cause the drive psi on a big N2O shot to really sky rocket along with egts. This will melt pistons unless the induction system is designed to run up there at that RPM.
I've broken more stock cranks than i'd like to count with fuel only and fuel with a smaller shot (.050 or smaller). Bigger shot, .090 and high rpm (converter not locking up during an event) and i started melting pistons. Keeping the N2O to below .050 at my level seemed to be a good balance. Pistons looked great and so did the rod bearings, stock crank was the problem.
Not sure if this helps, just some experience with set-up close to yours.
If you are on a stock crank shaft, you are already at, or over, what it can take. Adding a big shot to it will break it. If your drive psi is already up in the 100's on fuel, adding a big shot will not get you 300+HP unless you waste-gate the turbos.
Higher RPM (over 4500 rpm) will cause the drive psi on a big N2O shot to really sky rocket along with egts. This will melt pistons unless the induction system is designed to run up there at that RPM.
I've broken more stock cranks than i'd like to count with fuel only and fuel with a smaller shot (.050 or smaller). Bigger shot, .090 and high rpm (converter not locking up during an event) and i started melting pistons. Keeping the N2O to below .050 at my level seemed to be a good balance. Pistons looked great and so did the rod bearings, stock crank was the problem.
Not sure if this helps, just some experience with set-up close to yours.
Went 12.2-12.3 fuel only, 11.8-11.9 with spray.
Keep in mind this is on a big S400 frame charger and stock size injectors, so it has WAY more air than it needs on the spray.
I see two ways you can go about this:
1) Pull back some fuel in the tuning (pulse) and add some more spray until it's clean...then bring fuel back in.
2) Buy a bunch of jets (skipping a size in between--one of each size is overkill and $$$$) and slowly move up on spray keeping fuel the same.
I can't offer a whole lot of first-hand experience with BIG fuel on spray, and most importantly WHEN to spray to avoid backfire. What I can offer is make absolutely sure your EGT is high enough to produce a clean burn with the, what i assume is, low compression you run. Almost every single time I have seen an issue with spray on a diesel the smoke is GRAY as F and the spray begins too soon. Puts out the fire, engine chokes, continues pouring fuel, then guy lets off the button and BOOM.
I sprayed that single .102 jet right off the line as soon as my foot came off the brake. Compared to fuel only spool, the jet really made it fvck HARD in the 60'
Keep in mind this is on a big S400 frame charger and stock size injectors, so it has WAY more air than it needs on the spray.
I see two ways you can go about this:
1) Pull back some fuel in the tuning (pulse) and add some more spray until it's clean...then bring fuel back in.
2) Buy a bunch of jets (skipping a size in between--one of each size is overkill and $$$$) and slowly move up on spray keeping fuel the same.
I can't offer a whole lot of first-hand experience with BIG fuel on spray, and most importantly WHEN to spray to avoid backfire. What I can offer is make absolutely sure your EGT is high enough to produce a clean burn with the, what i assume is, low compression you run. Almost every single time I have seen an issue with spray on a diesel the smoke is GRAY as F and the spray begins too soon. Puts out the fire, engine chokes, continues pouring fuel, then guy lets off the button and BOOM.
I sprayed that single .102 jet right off the line as soon as my foot came off the brake. Compared to fuel only spool, the jet really made it fvck HARD in the 60'
Also, pull your timing below 2600RPM by 5-20%, depending on how you have it set currently relative to BTDC injection event.
You may want to check your solenoid size also. I used a purge solenoid for a long time and i would not pick up any HP after about .040 jet as it wouldn't flow anymore. I think a 3 AN line is good for .130 or so but not sure if it flows the same as a .130 jet would though.
Yeah and a lot of the smaller/cheaper/more common solenoids all have .078 orifice sizes. Make sure your orifice size is larger than the jet size. :thumb:
My Solenoid came with my Zex Diesel 300 HP NOS Kit . The chart that came with it says a .125 jet will get you a 300 HP increase as long as the fuel is there to burn . I run a 15# bottle with high flow valve that came with my pro race fogger system for my 600” gasser motor . I also increased 3 AN line to a 6 AN line . I may step it up 50 HP at a time . My NOS is activated by a micro switch at full throttle. I try to leave at 25- 30 psi and have not had issues with banging and popping as of yet . I do need to monitor the EGTs though to see where I’m at with NOS .
Kit I got (used) was off an early camaro. It was supposed to be a "200hp kit" but only came with a .073 jet as the largest. Different world we're in than the gasoline community when it comes to nitrous.
you dont know it but i kept the bigger jet when we went to put it on years ago. had to make sure you didnt beat me back then :roflmao:
if you only knew the shit we've done to keep things secret from our buddies out here :rofl::rofl:. at one point, someone built there engine in full secrecy to really pour it on without most anyone knowing. they all thought his truck was built on a wednesday :roflmao:
Well, the best answer I can give is 2618 aluminum (what CP and JE use, maybe more) has a melting point of 1020F-1180F. That means you've gotta get the surface of the piston to that point. I know I pushed my stock motor truck to 2200f-2300f sled pulling without a problem, the pistons looked great when I pulled them out. I also have pushed my built motor to 1700-1900f sled pulling and running it hard without an issue.
For the short bursts you will do at the strip/pulling I don't think you will have an issue because the piston will pull heat away from the surface and disperse it to the rest of the piston through conduction as well as it will put heat into the cylinder walls, the air in the cylinder, oil (due to oil cooling nozzles). All that plays into effect. Also bowl design and head swirl have a huge part in the piston temps as well due to where exactly the combustion event happens. Tuning is another factor into where the event happens. Keeping the fuel spraying in the bowl is obviously safer and allows the bowl design to do its job.
With that said, I have seen guys have issues due to a long sled pull (loose track but truck is still gaining ground etc) where the piston temps do skyrocket because once the piston is saturated with heat (the heat gradient is established) it has no other "heat sink" or another medium to move the heat away from the surface (valve relief, bowl edge, bowl floor, top of the piston etc). I don't think there is a real "safe" number that anyone can guarantee not to have a problem.
I’m gonna have to do some test hits with and without NOS with my GoPro trained on my gauges to check the EGTs and DP .i wondered if NOS wouldn’t actually lower my EGTs due to fact that my boost air gets plenty hot to where’s actually blistering my powder coating from the heat . And this is even from my 369s feeding the 72 in the Valley . Then it gets even hotter on the high pressure boost pipe pre intercooler ., The cold pipe leaving the intercooler does not blister the powder coating but I’m sure the boost air is still hot .,
Nitrous will cause an EGT drop but you will have to find what amount/jet it takes to do such. You have to go past the point of burning all the fuel to get to the cooling point if I recall correctly.