Started my nitrous install on my race '68...

I started with the solenoids and test-fitted the bottle to check out possible bottle locations..

I think that the location of the passenger seat is the best location for the bottle as I can easily access it. I already have the vent tube that I'll install too. (required by NHRA/IHRA). I didn't bolt down the bottle hold down brackets yet because I wanted to check if that bottle location is ok?

Installed the solenoids and the fuel line from the regulator to the fuel solenoid. Tested it and no leaks so far. I haven't installed the plate yet as I don't have long enough studs (I'm using a 1 inch HVH spacer and the plate is about 1/2 inch, so I need studs for 1.5 inch spacing..
Routed the nitrous line to the inside but haven't attached it to the bottle. Any comments or suggestions are appreciated..

 

Looking good. But how do you intend to mount the bottle with the floors being fiberglass? Brackets mounted to the seat mounting points?

Also, since you are getting so serious about racing this car, why is it still dragging around the added weight of the interior? Do you still drive it other than at the track?

 

Will you be using an rpm activated window switch?

 

The remaining interior pieces are not too heavy.. My seat is a lightweight race seat.. The door panels aren't too heavy as is the carpet.. The dash also is not all that heavy.. There's maybe a 15 lbs weight savings potential.. Not worth the effort. Well, Anywhere I could mount the bottle is fiberglass.. I will use large washers and maybe a metal plate on the bottom. Don't think that there will be any issues..

 

I have the switch but might only use it to shut off the nitrous before hitting the rev-limiter (6800 RPM, rev limiter is set to 7000)
The nitrous will be button activated. I will use the same button that I use for the linelock.. After the burnout, I'll switch the 12-volt switch to the nitrous. Currently I use that for the 2-step but I'll remove the 2-steps for now as I'm not going to use the transbrake.. The main reason is that my tires are not meant to be used with the transbrake. They are radials and don't like to be shocked. There will be also another switch that comes with the nitrous kit that makes sure that the nitrous is only activated at WOT... I will only run the nitrous in high gear for now.. Maybe I'll try 1 or 2 runs, turning on the nitrous in 2nd gear.. but initially I'll only spray in high gear...

 

Looks good! I installed my bottle behind the seats on my '82, for weight transfer and to keep the passenger seat open. I don't know if you have room in your '68.



The WOT switch location took some head scratching, this is where I ended up placing it.

My next addition is a regulator to control line pressure. Since I bracket race I want my shot to be consistant regardless of temperature or level of fill.

NITROUS OXIDE PRESSURE REGULATOR
--------------------------------------------------------------------------------
Get all the horsepower you paid for by eliminating bottle pressure drop

Performance enthusiasts know the key to making maximum power is keeping nitrous bottle pressure between 900 psi and 1000 psi. Unfortunately, as soon as you start injecting nitrous, bottle pressure begins to drop and horsepower is lost. At the end of a typical quarter mile run, your nitrous system horsepower can be down as much as 20 percent! The cutting edge solution is the new ZEX™ Nitrous Pressure Regulator that mounts inline and eliminates this detrimental pressure drop by controlling the bottle pressure going to the nitrous solenoid.

The ZEX™ Nitrous Pressure Regulator features an advanced regulator with flow capacity in excess of 500 hp, making it ideal for any performance vehicle or racecar. This easy to install system is fully adjustable from 500 to 1100 psi. The ZEX™ Nitrous Pressure Regulator Kit features everything you need for a complete installation, including AN fittings, a pressure gauge and a complete installation and tuning guide.


I also plan to install a purge kit. Does anyone know the purge line size? I likely need to use a longer line than supplied to vent in front of the windshield. http://store.summitracing.com/partde...5&autoview=sku

Have fun. Remember, nitrous is not to be feared but must be respected.

 

My '68 is a convertible and the access to the rear is very limited... I will use the nitrous very rarely with my current setup.. Just once or twice to get into 9's and for a 10.0 index race. Other than that, it'll only be used as a strategic shot for bracket racing.. For example.. if I spin off the line and have to catch up etc... I'll also only keep the nitrous set to 100 HP for now.. When I'll get my next engine, I'll spray the full 250 HP.. I'll also get more goodies for the setup like bottle heater and purge kit... I have the retard system also going in so that the timing only gets retarded when I push the nitrous button..

 

It looks like you are running the nitrous side fuel supply out of the same regulator that you use to supply fuel to the carb? If so this is not the way to do it when you get more serious, for now up to 150 hp or so it will be ok. Doing it that way makes it tough to adjust the flowing fuel pressure to the nitrous side fuel supply......ie harder to tune. Those little fuel pressure gauges are POS..I would not trust it to flow the fuel pressure. Do you know how to flow the fuel pressure?

The size of the line supplied with the purge kit will work, I upped mine to 1/4 in. To be consistent you need a purge kit.

If you have an HP carb there is a bolt on mount that screws into the side of the carb that mounts the WOT switch in a good spot, it will also not move around.....that can be a problem.

 

The instructions that came with the kit suggest 6.5 - 7 psi of fuel pressure. I know that they are conservative with fuel pressure and jetting but I'll be conservative too as I only need to get 3.5 tenths off my ET to reach my goal.. It's a different story once I'll get my next engine...
I will not try to get the maximum out of the setup at this point.. I will stay very conservative with my tune..
I usually set the fuel pressure at idle and set it between 6.5 and 7..
Consistency isn't a huge issue as I won't use the spray when bracket racing..
I already installed the switch.. Found a pretty good position..but it still could move...but I doubt it as there's little pressure on the switch when it's activated..
Planning on getting the carb studs and some additional parts tomorrow and will finish most of the install. I'm still waiting to receive the retard system... I'll definetely need that one... Will 3 degrees retard be enough for a 100 shot?

 

What is the compression of your motor and what fuel do you run?

Yes, the kits come very rich. I know we went over this before....are the jets the same size on both sides? nitrous and fuel??

The problem with running them fat is you not only do not get the most out of the system, but if you can damage the engine. You will be fine runing them fat at the at the lower power levels; but at the higher power levels you want to run them right, not fat.

If you want to; make a run with the nitrous on a fresh plug and we can go over how to read a nitrous plug. What plugs do you run?

I am voting for a 2nd and 3rd gear charge to get your 9 sec time slip.

 

12.8 : 1 and I run Sunoco 112 octane leaded (109 MON)

nitrous 55, fuel 61
I know that's rich but Edelbrock claims that their dyno results were achieved with that setup...
I'll have to check what plugs I'm using as they were changed after the rebuild. According to Edelbrock, I need 2 steps colder plugs..
I'll do whatever it takes

 

For Olivier's future info and for mine, wich side would you back down or increase? The fuel or the nitrous? I know you say it doesn't matter at that level (which is all I'll be running), but I would still like to make sure that I get what I can from mine while minimizing any possibilities of detonation.

 

Oliver: The jets are over square with 6.5 lbs? wow that is really rich. A good base line is the jets square and then flow the fuel to 6.5, still rich but not a bad place to start. That being said it will still make power the way you have it. One good thing about the kit being on the rich side is that it will help with any potential detonation. I am 95% sure you will be fine with pulling three degrees out of it, if it were me I would square the jets, flow it to 6.5, and pull four degrees out.

For future reference get NGK-9's when you decide to run heavier loads of nitrous. I have put over 50 runs on mine and the last time out I set my two best et's. I know I should not run them that long but the nitrous keeps em pretty clean The NGK's are a very easy plug to read and they go well with Sunoco fuel. I run their 110 blend in my 454 (10.7 to 1) with a 300 shot. I am going to step up to a 350 hit soon and may have to use 112 then. Because I run a Fogger I run the timing pretty aggresive so I will do an all 8 plug check when I bump it to a 350 hit. Just for reference my current 300 tune is .032 jets in all 16 flowed to 5.7-5.8 psi, 900-910 in the bottle and I pull a total of 10 degrees out.

Litevette: The standard tunes come out of the box rich so the average uneducated nitrous user does not burn the motor up. What a lot of people do not realize is that it is not the nitrous that makes more power, it is the extra fuel. All the nitrous does is help the motor burn the extra fuel. As far as the jets go you could go in either direction, but I would run them both the same size (called square in nitrous lingo) and then flow the fuel to 6.5. That would be a very safe tune and rich in 99% of the motors you put it on. After that you need to go to the track, make and run and do a plug read.....tune from there.

 

The kit says that with 6.5 - 7 psi fuel pressure and their recommended jetting, the final A/F will be 11.0 : 1
Like I said, I'm not trying to tweak the system too much with my current setup as engine as also tranny will be close to their limits even with only a 100 shot..

 

Ya, I know what your goals are now. I am just trying to get you thinking about the "right" way to do it when you are running 250+ plus hits. I know you want to eventually run a lot of power on the nitrous said, and I want to help you do it without hurting anything.

One more thing is do not think about the nitrous side as A/F ratio. Nitrous has more oxygen in it than the air we breath, so it is a skewed way of comparrison. Think of it as N/F ratio based in lbs per hour burned. In those terms most nitrous kits are 4.5-5 to 1(very rich) N/F ratio. Some guys will run thier tunes upwards of 6 to 1 (lean). The key is to find that sweet, safe, power making tune in between.

 

Thanks for all the information! I'll definetely tweak the nitrous setup once I'll have my next setup installed (engine and tranny)...

 

Yes, thanks also for the info! I'm adding this thread to my "favorites" list.

 

I have a 1985 elec pump with a return line set to 6.5 psi with a Mallory regulator so I think I will get plenty of fuel. I have a ZEX spray plate, supposed to be more efficient than a NOS spray bar. What do you mean by "square jets"? ZEX does not recommend the same size NO2 and fuel jets.
Per ZEX:

EFI WET SYSTEM
8 CYL. FUEL / N20

75hp 26 / 40
100hp 30 / 46
125hp 34 / 54
150hp 38 / 67
175hp 43 / 83

Per Holley, the purge line is 1/8 tube available at any hardware store.

I have an LM-1 data logger to record F/A ratio. I plan to start with the 75 shot and go from there. My NO2 regulator is on back order so I won't be testing for a couple of weeks. I will post results when I have them.

 

Hmmmm. if your pump is set to 6.5 psi, you might have a problem. Under acceleration, you might not get enough fuel... My pump is like 14 psi at the pump and my regulator regulates it down to 6.5 - 7 psi... You will lose pressure under heavy acceleration and that's why you want to run the regulator very close to the carb..

 

Are you running an EFI set up or a carb set up? You are listing EFI jet maps that if you run with 6.5 lbs. of fuel presure will cause major problems. EFI jet maps are meant to be run with the very high fuel pressures EFI pumps produce. Can you post a pic of your set up?