How much spray?
 

Hypothetically, if I run 5.7s in the 1/8 how much spray would it take to be solidly in the 5.3s in the 1/8?

If your running 5.7s in the 1/8th then your making at least 750 hp ( don’t know the cars weight) so a 300 hp shot should get you there and 400 for sure.

Just note that if you ever run the 1/4 with that set up the car will need to be set up and legal to run in the 8s because that’s what it will do with that hit of Nitrous.

Brian,
That is not as simple a question as it seems. Adding spray is not the same as adding N/A HP. You are adding that HP everywhere on the curve. Which can mean a large amount of torque at low RPM. So it comes down to how soon can you start spray and how fast can you ramp it in.

Stan

Our experience was to use as much N2O as possible as soon as possible in the run. We tried many, many different configurations to get the quickest ET's. Progressive controllers, 1,2,3 stages. Clutch switch, throttle switch, transmission switches. If you have a good enough suspension and tires, hit it it hard at the start. We had a 3000 lb. car, manual transmission. We had our quickest times by far with 400 HP on a single set of port nozzles on a clutch switch and another 200 HP on a 2nd gear transmission switch was about 1 to 1.2 seconds into the run. That worked the best for us with a heavy car. The second stage added about 20 MPH to the trap speed. This was all quarter mile stuff. But we were in 5th gear at about 600 ft. approx. In our experience, the progressive controller was smoother and easier to drive on a lousy track but did not produce the best ET's or MPH.

I sprayed a 300 shot the entire quarter mile to go from 8.30's to 7.80's in the quarter mile. This was in a 95 Firebird which I ran Top Sportsman with a NA 900hp 535 Pontiac at 2700 pounds. As mentioned earlier you need to spray it early to make any big gains. Don't try it without significant upgrades to everything. In my experience you will need a billet crank, excellent rods and a trans/rear end to match. Feel free to IM me if I can help and share my detailed experiences.

We ran a 541 Cu In. engine, about the same HP as aaronman NA. To possibly help anyone running large amounts of N20, I recommend running more timing retard than you might think is correct. We made best power at 32-33 degrees BTDC on the dyno, NA. On track with a digital MSD box and ICT, we took the full 25 degrees of timing out down track when using both N20 stages. This left us at 6-7 degrees BTDC down track. We found this was ideal for our particular set-up after sacrificing multiple sets of pistons to the aluminum Gods. It was an expensive learning curve, but we also learned the hard way, a Pontiac is not a BBC! At the time we were learning this, most of the 500-600 HP nitrous engines were BBC based so we used their experience and advice as a baseline. We are talking about the early 2000's. When you finally have too much retard, the only real downside is the car will slow down a touch. At that point, we would add back in 1 degree.

What is considered large amount of nitrous and what is considered small enough to not worry about building it specifically for nitrous?

It’s been said that to run those levels of nitrous oxide, in other words making that much added hp per cylinder you really need chambers designed for that much wet flow.

This is where a canted valve head such as the BBC you mentioned has a advantage over a wedge chamber as in a typical Pontiac head.

Brian,
I have not run N2O, but from having talking with people who have. I think you will need a cam change (More exhaust duration and maybe LSA change) before you reach a level where you will need to do softening.

Stan

Stick a big dome in the chamber ..... Poor man's softened chamber

We initially started spraying the Grocery Getter around 150 hp and that was easy. No worries about distribution, individual cylinder timing, special cams, etc. Memory is blurry but I think life got more complicated above 200-250 hp??

Eric

For a 300 shot of Nitrous I pulled 12 degrees of timing with KRE Hi Ports. Do NOT attempt this with a forged crank & lower hp rating rods unless you are feeling lucky. Through the years I've learned crank flex is a problem around the 1000hp power level and above due to significant cylinder pressures.

Leech told me the same thing about after 1000 HP he had issues with the forged non fully counter weighted crank and non billet pistons.
Fortunately, that kind of power is not in the plans.

We run a 496 ci. On motor 5.60 in 1/8, 150 shot starting at 1 sec for 4 sec is 5.309/129.32mph @ 3500 DA Radials

I launch mine right off the start, 275 shot.

GT

Dragraceroo........perfect answer to OP's original question.

What system are you using?

MSD Grid

Sorry, what nitrous system?

Yeah, had a 50-50 on question. I believe it's the Nitrous Express Hitman Dominator Plate . I had 100,150,200 hp flowed by Horsepower Innovations ,Using a Horsepower Innovations 1150 e85 carb, and 150 shot e85 fuel as well. Never hurt anything