Experienced Nitrous Users Step In

[Last_in]

I am a newb when it comes to nitrous and have some questions.

My truck on motor has ran a best of a 12.4 @ 111 and I would love to be in the elevens on motor but it doesn't look too promising. I still have to install the 58mm tb, qa-1's, built 46re, and buy caltracs but I still don't see a eleven second n/a pass. So I am going to rely on nitrous to achieve this. I never planned to but I have to try to keep up with my buddies kb cobra and turboed s2k. :jester:

What is the biggest/safest shot you guys recommend I use on my motor? It's a fully forged 408 with eddy heads, arp main studs and head studs, currently using Fel-pro head gaskets. My block however is not half-filled. I am running auto lite 3923's. Would my cam play a factor in the size of shot I can use?

What kits do you guys recommend? I want to use a 4bbl nitrous plate also, so if you give me part numbers that would be great. Would a wot switch or window switch be better?

Sorry for all the questions, I just want to learn all I can before I spray it.
Thanks

[blk00rt]

I am a newb when it comes to nitrous and have some questions.

My truck on motor has ran a best of a 12.4 @ 111 and I would love to be in the elevens on motor but it doesn't look too promising. I still have to install the 58mm tb, qa-1's, built 46re, and buy caltracs but I still don't see a eleven second n/a pass. So I am going to rely on nitrous to achieve this. I never planned to but I have to try to keep up with my buddies kb cobra and turboed s2k. :jester:

What is the biggest/safest shot you guys recommend I use on my motor? It's a fully forged 408 with eddy heads, arp main studs and head studs, currently using Fel-pro head gaskets. My block however is not half-filled. I am running auto lite 3923's. Would my cam play a factor in the size of shot I can use?

What kits do you guys recommend? I want to use a 4bbl nitrous plate also, so if you give me part numbers that would be great. Would a wot switch or window switch be better?

Sorry for all the questions, I just want to learn all I can before I spray it.
Thanks

who built your engine? did you tell them you were going to use nitrous at the time they were building it? I had mine built to take a 250 hp shot all day. I would say talk to your builder and see what parts they used and what they think the largest shot you should go as they will be most framilar with your engine.

[Last_in]

who built your engine? did you tell them you were going to use nitrous at the time they were building it? I had mine built to take a 250 hp shot all day. I would say talk to your builder and see what parts they used and what they think the largest shot you should go as they will be most framilar with your engine.

My friend built my engine, he builds engines for the dirt and told me he doesnt have any actual experience with nitrous or boost. I said I might spray it later down the road and his response was the same. So if I want to use that, I'm on my own.

[dakrt23]

i would say that the biggest thing to be concerned with is how much the rings were gapped, i am pretty sure nitrous motor ring gaps are a little wider to allow for extreme heat/expansion of the rings that nitrous causes... if they are not gapped enough and you run more nitrous for longer than you should, the ring ends could butt together and with no place to go, will score your cylinder wall to hell... if he builds oval track motors and setup the ring package like a oval track motor, that could be an issue... if he ran standard ring gaps then it should be ok... probably should find out...

the hard parts that you have in your motor would take a 200 shot no problem... factory shortblocks have taken 150 time and time again... i dont think a 250 is out of the question... that should put you in the solid mid-low 11s and with the 58/caltrac etc etc you might have a 10 in her with a solid launch...

you can always run a one size larger fuel pill (like 200 nitrous pill and 225 fuel pill etc) to help stay safe with the A/F ratio and keep things a little cooler in the chamber...

what stall speed are you running in your truck and what are the basic cam specs? also, what head gaskets are you using?...

truck looks great BTW!! keep up the good work...

[Last_in]

i would say that the biggest thing to be concerned with is how much the rings were gapped, i am pretty sure nitrous motor ring gaps are a little wider to allow for extreme heat/expansion of the rings that nitrous causes... if they are not gapped enough and you run more nitrous for longer than you should, the ring ends could butt together and with no place to go, will score your cylinder wall to hell... if he builds oval track motors and setup the ring package like a oval track motor, that could be an issue... if he ran standard ring gaps then it should be ok... probably should find out...

the hard parts that you have in your motor would take a 200 shot no problem... factory shortblocks have taken 150 time and time again... i dont think a 250 is out of the question... that should put you in the solid mid-low 11s and with the 58/caltrac etc etc you might have a 10 in her with a solid launch...

you can always run a one size larger fuel pill (like 200 nitrous pill and 225 fuel pill etc) to help stay safe with the A/F ratio and keep things a little cooler in the chamber...

what stall speed are you running in your truck and what are the basic cam specs? also, what head gaskets are you using?...

truck looks great BTW!! keep up the good work...

When I see him this weekend I'll ask him. I'm currently running a PI viper 3800 stall. Fel-pro 1008 head gaskets.
Cam: .585 intake/.580 exhaust 242 intake/248 exhaust 112lsa
Thanks, your truck looks so sick, I just might have to look into ccw's.

[dakrt23]

right on man, you got all the good stuff in your engine... definitely have a nasty cam too... do you have SCT tuning done? or what are you using?...

you should launch pretty hard with that 3800 converter too... if you really do end up putting 200-250 through that motor i am gonna be watching closely to see how she runs... it will run quick no doubt!

do you have slicks? you are gonna need em! 29.5x12.5 would be a good slick for that setup i think... might as well get some matching skinnies for the front at that point as they REALLY cut down on the weight of those heavy R/T 20s...

thanks for the compliment... the wheels really set off the whole truck and i highly recommend them...

[slvr03dakrt]

I have a similar setup on my 408 and I've run up at a 75 shot with ease and she ran mid 11's. You have the right stuff in your motor what heads are you running and how many cfm are they flowing and what was your final compression ratio. I always felt safer running a 75-100 shot than going all out on a 150-200. I'm currently running connsistant 12.1's @ 112 but I need a larger cam similar to yours mines a 236/24J0 with .575 lift on a 114lsa. Always start small on the shot and work your way up but those head gaskets should be good for 100-150 shot but I wouldn't trust them for much more than that.

[Last_in]

right on man, you got all the good stuff in your engine... definitely have a nasty cam too... do you have SCT tuning done? or what are you using?...

you should launch pretty hard with that 3800 converter too... if you really do end up putting 200-250 through that motor i am gonna be watching closely to see how she runs... it will run quick no doubt!

do you have slicks? you are gonna need em! 29.5x12.5 would be a good slick for that setup i think... might as well get some matching skinnies for the front at that point as they REALLY cut down on the weight of those heavy R/T 20s...

thanks for the compliment... the wheels really set off the whole truck and i highly recommend them...

I'm using SCT to tune it and hemifever got it dialed in pretty good after I sent him logs from my Lm-2. It would launch hard if I could get it to hook, the 4 inch drop with cheap drop shocks aren't helping much but the qa1's, caltracs and a c-notch to allow more travel will help it. I'm going to run hoosier 28X9 slick with the D06 compound on the 15x8's. I currently putting gen 3 viper brakes on the front, I need a minimum of an 18" wheel to clear. I would run skinnies but they seem to be 15"-16" only.

I have a similar setup on my 408 and I've run up at a 75 shot with ease and she ran mid 11's. You have the right stuff in your motor what heads are you running and how many cfm are they flowing and what was your final compression ratio. I always felt safer running a 75-100 shot than going all out on a 150-200. I'm currently running connsistant 12.1's @ 112 but I need a larger cam similar to yours mines a 236/24J0 with .575 lift on a 114lsa. Always start small on the shot and work your way up but those head gaskets should be good for 100-150 shot but I wouldn't trust them for much more than that.

I'm running eddy heads that were hand port and polished by my friend who built the engine. He doesn't have a flow bench so I cant tell you what there flowing. The compression ratio is 10.9. I'm hoping to run a little deeper in the 12's on motor with the new transmission and rear end set-up.

What's your 60 times?

[bad360rt]

I'm using SCT to tune it and hemifever got it dialed in pretty good after I sent him logs from my Lm-2. It would launch hard if I could get it to hook, the 4 inch drop with cheap drop shocks aren't helping much but the qa1's, caltracs and a c-notch to allow more travel will help it. I'm going to run hoosier 28X9 slick with the D06 compound on the 15x8's. I currently putting gen 3 viper brakes on the front, I need a minimum of an 18" wheel to clear. I would run skinnies but they seem to be 15"-16" only.

CCW makes "track pack" wheels for the Vipers, fronts are 17's or 18's, but they clear the brakes, and would still be lighter than stock wheels.

Sounds like everyone else covered everything, definitely find out about the ring gap before you spray big, but 100-150 should be fine and get you deep in the 11's (with traction of course).

[Last_in]

CCW makes "track pack" wheels for the Vipers, fronts are 17's or 18's, but they clear the brakes, and would still be lighter than stock wheels.

Sounds like everyone else covered everything, definitely find out about the ring gap before you spray big, but 100-150 should be fine and get you deep in the 11's (with traction of course).

Those wheels i'm sure are pricey new especially if I use them only for the track. I'll keep an eye out for a used pair. Maybe this year at Mopar Nationals someone in the viper club will let me borrow there skinnies to try to get a new best but I think i'm dreaming.

I just talked with the my engine builder and he said he used a standard ring gap not like he uses on his oval track motors.

[Intense RT]

Those wheels i'm sure are pricey new especially if I use them only for the track. I'll keep an eye out for a used pair. Maybe this year at Mopar Nationals someone in the viper club will let me borrow there skinnies to try to get a new best but I think i'm dreaming.

I just talked with the my engine builder and he said he used a standard ring gap not like he uses on his oval track motors.That's where it's good to have a build sheet. That's one of those things that would be nice to be able to look up later.

[Last_in]

That's where it's good to have a build sheet. That's one of those things that would be nice to be able to look up later.


Yeah I agree but It would be different if I had to pay for his labor. He built it while I supplied the parts.

[Five9Dak]

you can always run a one size larger fuel pill (like 200 nitrous pill and 225 fuel pill etc) to help stay safe with the A/F ratio and keep things a little cooler in the chamber...

DON'T run big shots needlessly rich. You'll do more damage than good.

[dakrt23]

DON'T run big shots needlessly rich. You'll do more damage than good.

interesting... i have always heard thats a safe way to go... what happens when you run it too rich?

[slvr03dakrt]

I'm running eddy heads that were hand port and polished by my friend who built the engine. He doesn't have a flow bench so I cant tell you what there flowing. The compression ratio is 10.9. I'm hoping to run a little deeper in the 12's on motor with the new transmission and rear end set-up.

What's your 60 times?[/QUOTE]
My 60' times are right around 1.68-1.70 with a good hook on 325 m&h drag radials on stock wheels front and rear along with stock 3.92 gears. Sounds like you have a good setup going but I def wouldn't spray more than 150 shot being your ring gaps are strictly for na apps or light nitrous use. Make sure you get a good nitrosamines tune also that pulls around 2-3 degrees of timing per 100 hp of nitrous and run good fuel with 10.9 compression and the added pressure on 93 octane you will be inthe verge of detonation so run a little race gas to bump up the octane on track days. That will also keep your head gaskets from blowing I would say your good to go on 100-150 max shot. I would get it to hook n/a before spraying or you will be chasing your tail. Im running a 2 in block on stock leafs with caltracs and a set of rancho rs 9000 oil filled adj shocks I purchased from calevert racing it hooks great even on drag radials. 60' nitrous times are mid 1.5s

[Five9Dak]

interesting... i have always heard thats a safe way to go... what happens when you run it too rich?

I've heard a few different theories. Some call it "rich knock" All I know is it creates irregular combustion characteristics. The torque curve will get jagged like it's knocking, or fall off hard up top. The tuning I did for an two stage ls1 car at school, it really killed the torque, and the knock sensors went crazy with above a 175shot if it was too rich. The smaller shots that people run on stock magnum long blocks usually just don't make nearly as much torque as they should, I haven't seen the curves get trashed like they are detonating with the 150 shot and below. BUT some people, like Alan, report that the 150shot doesn't pick up as much ET as it should at the track compared the 100. He also doesn't pull any timing.... so that makes it a crap shoot to figure out why.

It was a lot easier to tune bigger shots if you pulled timing, got the AFR to where the torque stayed up and didn't get all jagged, then dialed the timing back in. You might never find the AFR it likes if you run too advanced to begin with.

I was really surprised and laughed when I heard "rich knock" but nitrous definitely behaves different than boost, so the same "safety" nets don't apply. If I hadn't seen it clearly on the dyno I don't think I'd believe it either.

[Intense RT]

I've heard a few different theories. Some call it "rich knock" All I know is it creates irregular combustion characteristics. The torque curve will get jagged like it's knocking, or fall off hard up top. The tuning I did for an two stage ls1 car at school, it really killed the torque, and the knock sensors went crazy with above a 175shot if it was too rich. The smaller shots that people run on stock magnum long blocks usually just don't make nearly as much torque as they should, I haven't seen the curves get trashed like they are detonating with the 150 shot and below. BUT some people, like Alan, report that the 150shot doesn't pick up as much ET as it should at the track compared the 100. He also doesn't pull any timing.... so that makes it a crap shoot to figure out why.

It was a lot easier to tune bigger shots if you pulled timing, got the AFR to where the torque stayed up and didn't get all jagged, then dialed the timing back in. You might never find the AFR it likes if you run too advanced to begin with.

I was really surprised and laughed when I heard "rich knock" but nitrous definitely behaves different than boost, so the same "safety" nets don't apply. If I hadn't seen it clearly on the dyno I don't think I'd believe it either.Being taught as an NA engine builder, I'm definitely curious about this, but can't contribute much I don't think.:D I'm curious how nitrous affects the flamefront speed and propagation.

[Five9Dak]

We never went over it in my engines classes, so I don't know exactly the phenomena to be avoided, only the symptoms.

[grapejuice1998]

Never heard of rich knock, but I have heard of too much fuel wiping out the oil film that protects the cylinders and rings. I believe they call it fuel wash.

[Five9Dak]

Never heard of rich knock, but I have heard of too much fuel wiping out the oil film that protects the cylinders and rings. I believe they call it fuel wash.

Yep that's an issue at the extreme end of things as well. A lot of factory turbo cars run in the high 10s AFR wise and don't wash the rings out, but some nitrous cars don't like to be that fat in the higher revs.

[2ndGen360dakota]

I would suggest that you plan to spay a large amount of nitrous you talk to an expert on the tune like Steve Johnson or Monte Smith. Steve can be reached through yellowbullet.com and monte can be reached thru moparts.com. I would also recomend a msd digital 6 ignition and allows you to pull timing when the nitrous is activated. I sprayed a 125 shot last year pulling 6 degrees of timing and it worked really well.

[Five9Dak]

6 degress from what tune? It's important to remember most Dakota R/T owners don't know what WOT spark timing they are running, because they have email tunes, canned flashes, or mopar computers.

[grapejuice1998]

6 degress from what tune? It's important to remember most Dakota R/T owners don't know what WOT spark timing they are running, because they have email tunes, canned flashes, or mopar computers.

I never really knew (MP PCM), but I read my plugs a lot at first and figured there wasn't any reason to pull timing. I'm running nitrous to go fast, not sorta fast and uber safe.
But that's just me. I'm silly like that. :biggthumpup:

[2ndGen360dakota]

After looking at my digital 6 box its 5 degrees I have pulled out for a 125 shot. I have all the respect in the world for you guys that are doing it with the factory fuel injection set up because its clearly a challenge.