How much of a shot can a bolt on stock internal l98 handle contiously and still last awile. Other then retarted your timing 2 degrees for every 50 shot of nitrous and making sure your fuel system is up to par what else should i do? Im deciding between the edelbrock performer, NOS sniper, or NOS powershot. This is for a 4 barrel holley carb.

 

Most nitrous companies recommend keeping the amount of hp increase supplied by nitrous to 40% or less of what the motor makes without the nitrous while running on "pump gas" (92 octane) on a stock cast pistoned motor.
A very safe recommendation. Most nitrous companies recommend not trying to exceed 175hp (shot) gain on nitrous, on pump gas. (92).
If you want a bigger shot, use hi (110+) octane racing fuel.

A "150hp shot" setup on a typical street 350 makes a good hp gain and efficient use of the nitrous. (6 to 8 runs from a bottle) Most bang for the bucks.
You'll go faster with a bigger shot but the fun factor/dollar spent goes down from there.

I do not recommend that you "piggyback" the nitrous fuel feed onto your motor's fuel system.
I always recommend a separate dedicated fuel system to feed the nitrous.
Separate tank pickup, fuel line, pump and regulator as the fuel pressure and volume at the plate must be rock steady to maintain the right N20/fuel ratio.
Set the fuel pressure regulator (to the recomended fuel pressure) while flowing the fuel thru the plate or equivelent "test jet" into a bucket while observing the fuel pump supply voltage and fuel pressure guage on the nitrous system. This will ensure that when you engage the nitrous system, the fuel pressure will be right.

For big racing nitrous shots, I prefer that a small fuel cell be mounted under hood with its own dedicated pump, lines and regulator. This keeps the fuel lines and electrical wiring, short for best response and allows easy fuel changes.

Once you've established that your set up is correct and stable, you can experiment with the N20/fuel ratio for extra power by trimming the fuel pressure by a quarter PSI at a time +/- and see what works best on your motor.
(Requires a very accurate fuel pressure guage with high resolution)

The engines fuel system must be up to the task as well. if your fuel pressure in the traps is low to near starving the motor at max power/rpm, adding nitrous can be disastrous. Test your car first, observing the fuel pressure thru the traps in the quarter. If the motor's fuel pressure is 2PSI or less in the traps, fix it, FIRST.

Many many times, the first time a motor is exposed to nitrous, the spark plugs will foul. This happens because any carbon deposits on the piston top get blasted off and end up on the spark plug tip. This is pretty normal and par for the course. Be prepared. Bring a new set of spark plugs with you on your first nitrous test.
New spark plugs are required. You cannot clean the plugs to restore performance so don't waste your time. Once the motor is "conditioned" by the nitrous, this initial spark plug fouling will not continue to happen.
i like to use a spark plug about 2 heat ranges cooler than the stock plug. Sometimes a non-projected tip plug is nice. If your motor calls for say a AC R45TS plug, a AC R42T or champion RV8C works very well.

There are many off the shelf hyd performance cams with wide(er) LSA and extended exhaust duration that will enhance the amount of power you get from a specific "shot" level. Crane #113801 HMV278-2 is a good example. Especially if you advance it a few more degrees from cam card specs.

Your nitrous system will work best when the bottle is 85*F with 900 psi bottle pressure. A bottle heater with temp/pressure control and safety shut off, is nice. A big picnic cooler full of hot tap water and a nitrous pressure guage is nice to quickly establish the bottle temp/pressure is correct if you don't have a bottle heater. Just dip the bottle in the hot water and watch the pressure guage. When it hits 900 psi you're ready to go. Do not over heat the bottle. It will not make your car faster.
Do not do not try to heat the bottle with a flame. EVER!

If the nitrous system you buy does not include a inline nitrous filter, buy one and use it.

 

thanks that was very helpful can i run the colder plug all the time? I plan on 100hp shot with 93 octane

 

yes you can run colder plugs all the time without a problem. if you go to a bigger shot or plan to get 2 step colder plugs just for safety. im running 2 step colder NGK's and ive been running them for about 2 years with no problems.
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also the post above is great but you do NOT have to have a seperate fuel source especially for a 100 shot. on my bolt on LO3 i ran a 150 shot many many bottles without any problems. just tee a fuel line to the solenoid itll be fine thats how i run mine along with many other members here. you could probably do a 125 shot and last a long time with a stock motor. many members have run 150 constantly like me without problems but im telling you lower just to be on the safe side. you might be able to run that shot with pulling 2 degrees not sure on an L98 i know on my LO3 i did stock timing and it worked fine. other than that just be careful with the jets for fuel and make sure theyre safe better to be a little rich than lean.

 

Yes you can run these slightly cooler non projected tip plugs all the time.
The stock spark plug heat range is a compromise choice for most stock OEM application driving.
A car like yours and mine that sees a lot of WOT/hi perf/racing use can use a slightly cooler than stock spark plug like the AC R42T or Champion RV8c, even without nitrous or a supercharger. Especialy if your motor has higher than stock compression ratio.
This is actually a "hi-perf Marine" speced spark plug. Marine engines are always either idling or under full load @WOT for extended time. If the "stock" spark plug is AC R44TS or AC R45TS, then this is the right plug for you.

if you bother to set up your fuel system(s) properly as i discribed (even thou it is more work) you won;t need to limit yourself to a 100HP shot.
You'll have full reliabiity up to 175 HP. And that much faster than the next guy who just thru it all together the easiest way. I have gone much further on stock cast pistons and pump gas before but requires the right setup with exacting care.
You can have a lot lot of fun with a 150-175hp shot level on a typical SB.
A base 100hp shot is nice, but you'll soon be after more.
The ZEX perimeter discharge plate design looks good to me. Something to think about. What cam is in your motor now?

 

stock 89 l98 cam My plan is to try to go 12's all motor then once i accomplish that i will start spraying. Ive narrowed it down to 3 choices since im on a budget edelbrock performer, NOS sniper, NOS powershot. Im not the smartest about nitrous but when you run nitrous do you have a fuel and a nitrous solenoid then you need to run a fuel line to the fuel solenoid. I have a mallory regulaor and i have to plugs caped off right now could i run a fuel line to the solenoid threw the regulaor i really dont want a seperate fuel system but im definetley going with the plugs.

 

Nitrous does not care about what you don;t want to do. If you short change the fuel side of a nitrous system, you will,,, pay...again....
Your fuel system now is probabily barely enough to feed a 12sec motor.
Do you want a car that you have to worry about "will it work", "will I scatter the motor?" Or do you want a car that you have full confidence in.
Go to track, install slicks, Purge the nitrous system, and unleash the hounds.
Go fast and don't break parts. Its just that easy and reliable, when done right.
Install a separate dedicated fuel system for the nitrous system.
You can do it right the first time or learn the $$$hard way$$$.