"Occasional" Nitrous 150-300HP...What do Engine Builders/Nitrous Racers do to prep a build?

[biomedtechguy]

Please bear with me guys. I may never add nitrous to the stroker I'm finally taking action on to build. Yep, I sent the deposit on the BME aluminum block, so I know that isn't much $$ compared to the total cost, but every journey begins with the first step. I know I may struggle for a while to get traction, to keep parts from breaking, or after experiencing breakage, see that I have to make different choices.
Let's put that aside for now...
I would like to hear from those of you who have experience with nitrous motors. I've read there are things done in the build to accommodate or prep for nitrous. The "baseline" I anticipate is the BME block, 4.25 stroke, 4.5 bore 541 cu in displacement. TF 270s with the Weiand "tunnel ram" intake 6bbl top, Nitrous Express 2bbl spray plate(s). Cam profile should be fairly "mild" because I am counting on the displacement to lend a good bit of HP and torque to the total, and I'm only looking for 6XX HP and say 650-700 ft lbs torque.
If I see that I need a kick or I may not beat the guy I just picked up a grudge race against, or I've done what I can or am willing to to get the best ET/MPH but if I could get a little more I'd break into the next lower second ET or turn the MPH into the next decade, in other words I anticipate using the nitrous as an "emergency" button....
Is there a HP number that is low enough to not have to do anything special but high enough to cut a few tenths? Around what is that?
If a 6XXHP/690FT LBS engine in a 3,800 pound car needs a 250 HP shot to make it worthwhile, what do you do differently in the build AND what are the NEGATIVE effects of building the engine to accommodate nitrous, when you aren't using nitrous.
THANKS to anyone who will entertain my questions, I appreciate it.

 

[Fizz66Coronet]

With that much displacement you should easily make 700 hp with a mild build over 800 with the right parts. Best Machine built one 842hp and 670tq

 

[biomedtechguy]

With that much displacement you should easily make 700 hp with a mild build over 800 with the right parts. Best Machine built one 842hp and 670tq

I appreciate the reply. Those numbers (6XX HP and torque) are the range I've been "looking for" since I first thought about what kind of power would suit my application. More naturally aspirated HP than somewhere in the 6XX to 700, and around the same for torque, would cause problems or demand that I go in a direction I'm not interested in.
That is why I'm asking about nitrous, and specifically using it as an occasional "emergency" button, for the times I may "get in over my head" with a pickup race, or maybe something to aspire to if and when I get a handle on the power the engine makes on its own. It seems like a reasonable option to get some "headroom" should I want or need it.

 

[RemCharger]

Mainly ring gap. Go with the piston mfg specs. I'd build for a 125-150 shot. 300 is a different animal.Need a MSD with nitrous control.

 

[Fizz66Coronet]

Your welcome my 440 stroker made those numbers like many other people on here. Thats around a $12k motor I bet your motor will be $25-30k . 600 ftlbs of torque is a lot to handle on the street with a stock tub

 

[biomedtechguy]

Mainly ring gap. Go with the piston mfg specs. I'd build for a 125-150 shot. 300 is a different animal.Need a MSD with nitrous control.

Consider it a given that while I don't need "top shelf" parts at the power level I am looking to attain w/out nitrous, reliability is important because I want to be able to drive a "power tour" or other such event, making use of my 5th gear OD and enjoying my car in that way to, so with the investment in a serious block, I'm also not going to fill it with cheap crap either. I would expect the parts that go into the build to give me some "headroom" too.
Ring gap is what I've read about, but how does a "nitrous ring gap" negatively impact the engine in general, and when you're not spraying? If it causes excessive oil burning, blow by, and other negative consequences, then I'd limit myself to a "shot" that would get me a couple of tenths, and just leave it at that.
Generally speaking, where is that HP "shot" line that may only require a few degrees of timing to be taken out, but a "normal" or "non-detrimental" ring gap can still be set?

 

[biomedtechguy]

600 ftlbs of torque is a lot to handle on the street with a stock tub

Tub? Do you mean wheelwells? I don't have a problem with mini tubbing for a wider tire, especially if that lets me use a drag radial, granted that isn't the ideal tire for maximum traction.

 

[Budnicks]

100hp is no big deal, especially on a quality build already
150hp shot isn't a real big deal either

Quality forged pistons, good & high quality rings
(don't be budget cheapskate there, I'm sure you'll have,
I'd hope so at a min. )

Good quality seals too, you will be pressurizing the engine crank case
whether people admit it or not, good filtered vents/caps too

a tad bit wider ring gap, like 0.0005+ - 0.0010 wider won't effect
(at the hp levels you're talking), "the blow-by much if at all"
especially on a 4.5" bore

you should really talk to your engine builder, he should know
if he doesn't, I'd certainly go to someone that does
do not build by committee
that big of a bore it'll probably be even more ring clearance
it will tend to grow even more, the bigger the bore

I ran Childs & Alberts gapless/zerogap top rings, N2O or boost specific
& I never had any issues, probably not worth the extra cost either

I ran bigger bore (like 4.60+) & less stroke too, I built for upper RPM's 10,000+
(I had 2 or later 3 kits of progressive up-to about 600hp of N2O,
a plate kit 'under the carbs' for off the line, softer hit
a spray bar plumbed permanently in the manifold, if needed, ram effect
drilled & directed at the intake runners
& a direct port nozzle kit, directed right at the intake valves,
at the bottom of the intake runners (outside for easy access), for high gear)

Use a good dedicated N2O fuel system from the fuel tank to solenoid
& dedicated stand alone N2O fuel pressure regulator too
pref. a bypass style (IMO), you need a good flowing, 5psi at a min,
with absolutely no spikes in the fuel pressure, especially under WOT
or it can or will hurt the pistons, rings (lands) or even the valves
don't skimp on any of it
you don't want to go lean under N2O, it will burn or lift a piston
even at the 100hp-150hp level (mild in the N2O world)
or will lift the top ring lands in a heartbeat

Use good solenoids, (not just some cheap *** bargain kit)
make sure you have really good grounds,
solder all the connections on all the wires, not just crimps
(probably best to use 40 amp Bosch relays inline, to activate too, keeps it full 12vlts,
much less or no spikes)
& Use a good purge valve, to get pure N2O at the solenoids,
so it's not dead fat (fall on it's face) when you hit the N2O
for the 1st time, it will have liquid N2O right near
or right at the N2O solenoid

try to keep the bottle at like 750# to 900# psi
when you know you're going to use it, do not run it at 1200#'s psi
vent or purge it off
you can heat the bottle to get it up "some" a bit too
or cool it to bring it down (ice pack/bags) "some" too
it will hit far more consistently too, that way,
if you do the same pressures when it used, better for tuning references too
when it's under 500#'s psi, refill it don't even try & use it
I know it's sort of a PITA
But if you want it to work right & consistently right, it's a must

you wanta' play, you gotta' pay, price of doing it right & going fast

I'd suggest, get a progressive (good I hate that term progressive) timer/controller,
to take timing out down track, it will help the engine live longer
use a WOT micro switch & have a manual arming switch inside
so you can cut it off anytime
or if your too cheap to get a controller,
take out/retard about 4* per 100hp at a min.
it will kill some bottom end & lose a bit of 60' times,
if you don't have the timing, in it, to begin with, but will run good
on the back end
where the N2O will get a maybe a couple tents at the 100hp level

good electronics may just save it

not sure if these guys are still in business
or if they are the same guys running the show
they use to be really good, they truly really knew their ****
not all N2O kits are equal
not all solenoids are equal
not all electronics are equal either
if you can get medical grade N2O too, better no sulfur
been 6.69 @ 217 under N2O power
haven't run the stuff for a while since like 2008

 

[biomedtechguy]

100hp is no big deal, especially on a quality build already
150hp shot isn't a real big deal either

Quality forged pistons, good & high quality rings
(don't be budget cheapskate there, I'm sure you'll have,
I'd hope so at a min. )

Good quality seals too, you will be pressurizing the engine crank case
whether people admit it or not, good filtered vents/caps too

a tad bit wider ring gap, like 0.0005+ - 0.0010 wider won't effect
(at the hp levels you're talking), "the blow-by much if at all"
especially on a 4.5" bore

you should really talk to your engine builder, he should know
if he doesn't, I'd certainly go to someone that does
do not build by committee
that big of a bore it'll probably be even more ring clearance
it will tend to grow even more, the bigger the bore

I ran Childs & Alberts gapless/zerogap top rings, N2O or boost specific
& I never had any issues, probably not worth the extra cost either

I ran bigger bore (like 4.60+) & less stroke too, I built for upper RPM's 10,000+
(I had 2 or later 3 kits of progressive up-to about 600hp of N2O,
a plate kit 'under the carbs' for off the line, softer hit
a spray bar plumbed permanently in the manifold, if needed, ram effect
drilled & directed at the intake runners
& a direct port nozzle kit, directed right at the intake valves,
at the bottom of the intake runners (outside for easy access), for high gear)

Use a good dedicated N2O fuel system from the fuel tank to solenoid
& dedicated stand alone N2O fuel pressure regulator too
pref. a bypass style (IMO), you need a good flowing, 5psi at a min,
with absolutely no spikes in the fuel pressure, especially under WOT
or it can or will hurt the pistons, rings (lands) or even the valves
don't skimp on any of it
you don't want to go lean under N2O, it will burn or lift a piston
even at the 100hp-150hp level (mild in the N2O world)
or will lift the top ring lands in a heartbeat

Use good solenoids, (not just some cheap *** bargain kit)
make sure you have really good grounds,
solder all the connections on all the wires, not just crimps
& Use a good purge valve, to get pure N2O at the solenoids,
so it's not dead fat (fall on it's face) when you hit the N2O
for the 1st time, it will have liquid N2O right near
or right at the N2O solenoid

get a progressive (good I hate that term progressive) timer/controller,
to take timing out down track, it will help the engine live longer
use a WOT micro switch & have a manual arming switch inside
so you can cut it off anytime
or if your too cheap to get a controller,
take out/retard about 4* per 100hp at a min.
it will kill some bottom end & lose a bit of 60' times,
if you don't have the timing, in it, to begin with, but will run good on the back end
where the N2O will get a maybe a couple tents at the 100hp level

good electronics may just save it

not sure if these guys are still in business
or if they are the same guys running the show
they use to be really good, they truly really knew their ****
not all N2O kits are equal
not all solenoids are equal
not all electronics are equal either
if you can get medical grade N2O too, better no sulfur
been 6.69 @ 217 under N2O power
haven't run the stuff for a while since like 2008
View attachment 963300

Hey Budnicks,
All of the "walls of text" I have seen you post

I may have missed the ones about your depth of experience with nitrous, so I really appreciate you taking the time to explain, especially how it relates to my situation. Other than the micro switch, which is going to operate off of the outboard carbs opening, I'm also going to have a 1 second delay, because of the lean spike on tip in of the outboard carbs that so many speak of, but I've seen on my Innovate Motorsports dual wideband O2 system. No "squirters" makes it inevitable, it would seem. Nitrous + Lean = bad, even for a second.
If I'm still using the Holley carbs, it's 100% certain I'll use a S.A.F.E. fuel tank (with some 100LL AvGas or better in it, get an octane BOOST right when I need it). It includes a dedicated electronic fuel pump and pressure regulator, TOTALLY independent of the carburetor fuel pump and system. I may still go that S.A.F.E. route if I have the F&B 3x2 EFI direct port injection system, but with the fancy ignition system and computer control unit (not sure which one, but I'll X that bridge when/if that day comes) and high pressure fuel pump all that fancy **** uses, it may be as good or better to incorporate the nitrous control into the EFI control system.
You know by now, I get ideas and talk about "stuff" l o n g before I actually do it, partly to get ideas, sometimes I even change my mind (rear suspension), and a whole lot of motivation and encouragement, even if some think I'm

I guess the MOST important question, which you mostly answered, is "how many HP" shot of nitrous can an engine like the one I'm planning take before its build design methods have to be altered to accommodate that. I can't imagine going cheap on key parts, so no failure there, and I got the reference to ring gap, so thanks for that. I'd hate to build it to where it really "suffered" because of nitrous specific designs or specs, and then I find out I'll never use nitrous.
The BIG question(s) is/are:
Can I pick up a few tenths and a few miles per hour, without any detrimental nitrous specific ring gaps etc being done during the build?
AND
With a baseline of say 650-700 HP/TQ how much of a "shot" would it take to cut a few tenths or a HALF a second off a quarter mile ET in a 3,800 pound car, and if that means 200-300 more HP well how do those design modifications negatively impact the way the engine behaves the 98% of the time it's NOT on "the juice"

 

[biomedtechguy]

With a baseline of say 650-700 HP/TQ how much of a "shot" would it take to cut a few tenths or a HALF a second off a quarter mile ET in a 3,800 pound car

To show y'all that I make an effort to get some answers myself I plugged some numbers into the Wallace racing calculator. I realize this is an estimate, and is based on a good run. VERY interesting!
Baseline, using 675 as my HP, I get this:

Adding a "100HP shot" if I get 100HP:

So that would get me from "the 10s" into "the 9s" which made me think about my buddy's yellow 'Vette and his 9.8 run at 139 MPH, so I tried a "150HP shot" and that gives this:

Like I said, that is a guestimate, and assumes a good run.
Looks to me like a 100-150 shot, especially if a well built engine doesn't have to "suffer" from nitrous specific build spec "ring gap" or other "off the spray" detrimental mods is WELL worth having that option available!

 

[Budnicks]

getting over a certain level will dictate different camshaft & timing too
engine built for N2O are like boost engines, they work best on the bottle
not as good off it

to move a 3900# car even with 650hp, to get another 1/2 a second in ET
unless you use it the whole way off the line & down track
a 250-300hp you could go to www.wallaceRacing.com
& play with #'s see how much it needs to work & achieve it
250hp-300hp N2O kit real HP, not advertised BS
will probably be needed at a min

I've seen 1 full second improvement on good sorted out N2O kits
even on engines not exactly spec'd out for N2O use

grants you the specific HP rated jets or kits for 250-300hp probably
just because it has 250hp jets in the kit,
doesn't necessarily mean it will make 250hp
more in likely It won't make 250-300hp at the rear wheels
(advertising up-sale BS)
your specific engine may require a different N2O system 'jetting'
smaller on the fuel side & larger N2O side
or visa vesra, on either the fuel or N2O side, to actually achieve them #'s
the bigger the engine the less difference it seems to make
you really need big changes, to make big HP changes

your ignition system will play a big role, it may keep it alive
& make decent power without hurting anything
IF you want to get the most out of the N2O
a lot will & depends on cam timing, overlap or centerline of the camshaft too
a milder street cam with like 112* than like 0.550" gross valve lift to
0.600" gross Valve lift
will feel like a 250 shot adds way more power
than a camshaft with like 108* & something like
0.650" GVL designed for a N/A multiple carb combo will feel like,
a camshaft that isn't selected for use with N2O use

it can add power but just not as efficiently

250-300hp added in N2O
starting to get at a level where more isn't always better
at that level, more doesn't always work better
unless the engine is set up to use N2O
it becomes diminishing returns
can the intake handle it can the ports handle it
or is it just becoming a waste

if that makes any sense

just throwing a big kit on a big motor
& big *** camshaft isn't how it works

when you start to add that much extra in fuel & N2O
at the 250hp-300hp levels
you really need a camshaft designed to use N2O or boost of some sort
get the gases out
to get the best out of a N20 system, especially on the exhaust sides

it's been almost 15 years now too
I hope I'm not forgetting something

 

[biomedtechguy]

Thanks again Budnicks.
I'm VERY fortunate, since IQ52, my friend Jim Laroy, TOTALLY understandably wants to spend time with his family and the spectacular outdoor life where he lives, and God knows he's earned it, isn't taking new builds, I'm very fortunate to have found a VERY capable, MOPAR specific depth of experience shop in Southeast Performance in Tampa! There's a lot of reasons why John Mercedes and I hit it off, and the equipment AND personnel there have what it takes to make the most out of my investment.
Since Bill Mitchell said they were switching from nodular iron main caps to billet steel caps in the block I put a deposit on, I called BME just to see if they had made the transition (although either cap would work for me). Bill Mitchell himself took my call, and said they were using the last of the iron caps now, and my block would have the billet steel caps.
I thanked him for doing these and the Hemi blocks for the Mopar nation, and although I know he may be biased, I explained my reasoning behind going with one of his blocks vs my other options, and he agreed with my train of thought.
Bill was a pleasure to talk with, and he SPOKE HIGHLY about John and Southeast Performance!
I expect to have my first serious chat with one of their builders there, and I've decided that having nitrous as an option is worth discussing, and I'll see what they say about the differences are and figure out what the point of diminishing returns is.
I guess the best thing that has come from putting this idea on the forum is that I'm convinced that for my purposes, it's definitely worth having the ability to add a nitrous spray plate setup, even if it only adds 100-150 real horsepower, that could make the difference between me or my buddy crossing the finish line first, and even if it didn't involve a friendly rivalry between friends, there are a LOT of cars in our "category" that having the "backup" of a little nitrous "kick" could determine who goes on the trailer, and who gets to claim bragging rights.

 

[MOPOWER871]

I would definitely have a low fuel pressure sensor wired into the fuel system at the fuel solenoid / fuel solenoids... so it will shut off the system. It only takes a few seconds to melt down a motor. there's a lot going on in a 9,10 second car. I always wired in pro lites to my low pressure sensor .oil system , fuel systems. a light will get your attention instantly. Good luck

 

[biomedtechguy]

For those not familiar with the Nitrous Express S.A.F.E. stand alone 1 gallon tank, electric fuel pump, and pressure regulator, (there are several, this one is ideal for carburetors) here's the one I've been looking at. I would have to talk with Nitrous Express and see if it can be upgraded and how, if I switch to the F&B 3x2 EFI/Direct Port injection system, or is there a better choice that will work with the 6bbl carbs now, and the EFI/DPI later.
I AM ABSOLUTELY SOLD on this concept!
I think it is BRILLIANT!
From the description:
The Nitrous Express SAFE (Stand Alone Fuel Enrichment) system improves the performance of any nitrous system. The SAFE system includes a one gallon, high strength, composite fuel cell that can be mounted in most factory battery trays without modification. This version of the SAFE System includes a low pressure external fuel pump and non bypass style regulator.
Here is something I alluded to in my post, if, for example, the 1 gallon of fuel is 100LL AvGas or Sonoco Turbo Blue 109, etc: When used with race gas, the need to retard timing is significantly reduced. The SAFE system reduces the need to upgrade OEM fuel pumps, and will completely eliminate pressure drop at the fuel rail in EFI vehicles.
https://www.nitrousexpress.com/stan...temsafe-external-pump-and-regulator-15003.asp

 

[Dodge 330]

You can easily do your own stand alone system for a lot cheaper and it is just as good. We use a JAZ Jr. Dragster fuel cell and a small electric pump for our dedicated supplemental fuel system.

The more you go over the 150-200 shot the more you need nitrous specific things like colder plugs, bigger ring gaps, progressive controllers, etc. Keep it under 200 IMO and you'll be happier. Much more and the build encounters lots of compromises. Budnicks advice is spot on!

 

[Hemirunner]

You’ll have your hands full with just the stroker. Once you get past a 100 shot, you really need to have the tune right or you can hurt parts quick. If you think you might add it someday, just gap the rings accordingly so you don’t have to tear it down later. I sprayed 200 or so on a 750hp hemi using a single Holley black pump and two regulators. You’ll be picking gear clusters off the track with that manual and 300 shot, lol. I’m

 

[biomedtechguy]

You’ll have your hands full with just the stroker.

I'm sure. Looking for a little "headroom", if and when I get a handle on the horses.
I wouldn't expect to go over 150 shot, but that's part of why I'm asking the questions I'm asking in this thread.
Thanks.

 

[440rb]

Well with that motor and the torque it'll have, adding N20 to that being stick is not the best idea tbh, there's no way I think you can use that off the line in any situation, all that would be good for is perhaps hit the button in 3>4th down the track with slicks, on the street it would be bad news, so is it worth all the expense of separate fuel systems etc. etc. for what 2>3 10ths gain and some mph, if your running 10.1's>2's@129NA perhaps it is for you? but a 1/10th or 2 can normally be found from the tyres, the chassis and some AFR work etc. I don't even think we would consider it on our 720ftlbs mild 10:1CR 589ci 4.500 stroke combo, and we run a 727, the car is just not set up for 900ftlbs although it runs a Dana /caltracs/mono's etc. and I was always ready to run N20 and did for many years up to a 250shot on the 340 small tyre and a 175 on the 440 big tyre car but both 727 cars and strip only.....

Here are just a few scenario's of its projected performance @3800lbs all in, 4.10's?...28" tyre?
at 700fwhp,>
60 Foot E.T. : 1.42
1/8 Mile E.T. : 6.46
1/8 Mile Trap Speed : 105.23
1/4 Mile E.T. : 10.24
1/4 Mile Trap Speed : 131
1/4 Mile Trap RPM : 6,445
at 800fwhp>
60 Foot E.T. : 1.36
1/8 Mile E.T. : 6.18
1/8 Mile Trap Speed : 110.02
1/4 Mile E.T. : 9.79
1/4 Mile Trap Speed : 137
1/4 Mile Trap RPM : 6,738
at 850fwhp>
60 Foot E.T. : 1.33
1/8 Mile E.T. : 6.05
1/8 Mile Trap Speed : 112.26
1/4 Mile E.T. : 9.60
1/4 Mile Trap Speed : 140
1/4 Mile Trap RPM : 6,876
but these no's are assuming a good hit off the line and run through to the traps which I doubt will be the case unless you power shift it.
just my thoughts.

 

[68 HEMI GTS]

You’ll have your hands full with just the stroker. Once you get past a 100 shot, you really need to have the tune right or you can hurt parts quick. If you think you might add it someday, just gap the rings accordingly so you don’t have to tear it down later. I sprayed 200 or so on a 750hp hemi using a single Holley black pump and two regulators. You’ll be picking gear clusters off the track with that manual and 300 shot, lol. I’m

540 cubes, nitrous, stick shift, vacuum secondaries, and in a car with no tubing. What Could go wrong... it’ll be a beast for a pass or two.

I think a regroup is in order. That engine in that car needs nitrous like I need 2 houses. You’ll be hard pressed to get it down the track on motor. Some tubing in the car is an absolute must. One for safety and secondly just to stiffen the thing up. 2 door hard top b bodies aren’t the stiffest, even with frame connectors.

 

[Hemirunner]

540 cubes, nitrous, stick shift, vacuum secondaries, and in a car with no tubing. What Could go wrong... it’ll be a beast for a pass or two.

I rattled a lash cap off at 8000rpm when the u-joint broke as 2nd gear hit. Valve hit the piston. It took out a rod bearing. Nitrous on this particular combo is going to be like that on every pass. Carnage is highly likely.