ihengineer76

Good afternoon, fellas! Now that I have my car back on the road, I am starting plans for next summer. I am thinking about putting on a nitrous system and would like some insight on which systems work best for you guys. I am looking for about 100-125 hp. The engine I am running is a 362 with forged rods and pistons, about 10.75-1 compression, ported iron heads, .504 lift 228 duration cam, full length headers, and a Holley 750 with vac secondaries. TH350 and 3.42 rear gears. Just wanted to know which system seems to work the best and is consistent.

Thanks much!

Tom

captjim

I had the Edelbrock Performer kit, worked fine. The jet combos are fat, safer that way. I used a custom tune, 53/57 jets at 6 psi. Added around 100 HP, knocked .12 off from 13.9 to 12.7.

However, with your combo you are going to have issues. IMO the Cr is already too high, your cumbustion pressure is going to be too high for pump gas without nitrous, IMO, with it you are going to do damage, even if you pull some timing out.

ihengineer76

The nitrous at the track would be with pure 110 leaded race fuel. Also, I redid my compression calculations with two other calculators and they were both lower than the one I originally used online. Real ratio is 10.54. So far, I have been running the car on a 10% blend with 15 degrees initial and 36 final in at 2800 and no issues yet. Once I get the engine completely broke in and am very familiar with it, I will back off to just straight 93 and pay close attention. Also, with the cam I have, my dynamic compression is at 8.04 which is in the "safe" zone, but not by much. I will just be careful and pay close attention to the engine.

ah64pilot

Whatever kit you get make sure it's a wet system and has provisions for a fuel pressure safety shutoff switch. You don't want to lose fuel pressure and NOT lose nitrous.

ihengineer76

Yeah, I agree with you on the fuel pressure switch, ah64pilot. I was going to set it up with a throttle trigger switch to come on at WOT. Do you run a purge valve?

ah64pilot

I don't run nitrous on my car...but I installed one on a buddies '68 Pro-street camaro last week. He bought a car with a kit already installed and someone butchered the wiring so we straightened it all out.

Anyway, yes. His set up is almost as safe as you can be. It's a wet system with 2 electric fuel pumps. One for primary fuel feed, the other for the nitrous fuel feed. It has a purge valve and bottle warmer. His system is a throttle trigger system as well, it only comes on at WOT and ONLY when the secondary (NO2) fuel system has pressure on it.

I installed a primary switch that arms the system, but can be interrupted if the fuel pressure switch is not active (no pressure). I also installed a momentary switch that is piggy backed off the primary arming switch so that the purge valve can only be opened if the primary system is armed.

I didn't have any instructions so you'll already be ahead of the ballgame if you buy a brand new kit. I was having to think back to my speed shop days.

ihengineer76

Well, it sounds like you knew what you were doing! I have never run nitrous on anything. The closest I got was doing a propane setup on a friends diesel truck. I am still not completely decided on whether I will run spray or not, but I wanted to have a full understanding of it before I even considered buying a system. Thanks much for the info and insight!

ah64pilot

Nitrous isn't quite the same as propane injection on a diesel lol! I have seen trucks with the tank in the bed, a steel pipe run through the cab and firewall that just had a ball valve on the pipe so the driver could turn it on at will lol! Diesels are a little more forgiving with propane than nitrous on a gas engine.

If you do go for it...take your time and make sure everything is operational before you fill the bottle and make a pass Good luck!

SBORule

Just got done reading your build thread over in that other category.

Don't recall if you upgraded the head bolts or not or what head gaskets you are using. If you are using stock head bolts, just buy a set of ARP head bolts and replace the stock ones and re-torque the new ones. Loosen up the intake bolts when you do that, if you need to replace the head bolts.

I would suggest an MSD Digital 6 ignition box if you don't have one, it's got a programmable single stage timing retard, I'd pull 3 degree's out as soon as the NOS is activated for 125HP shot.

If you can't afford that, you can always just retard your distributor timing so you have around 32 degree's total advance, you might find 30 degree's will make more power.

Use NGK R7 heat range plugs, R5 will probably be too hot.

ihengineer76

ah64pilot, we were slightly more sophisticated than that lol! We installed a computer controlled system that would adjust the mixture, and had a safety shutoff that returned to truck to normal operation when the tank was empty, or you just wanted it off. The main benefit was fuel economy rather than hp, but all in all worked well.
SBORule, thanks for the heads up on the MSD box. I was considering going with the Pertronix ignitorIII and manually back the timing off, but if the MSD box has this feature built in, that would be the better route. Currently I am running ACDelco plugs that are one heat range colder than factory. As for the head bolts, I will upgrade to those when and if I do decide go with nitrous.
Again guys, thanks for all the advice!

captjim

I too had the Digital 6 box, boost retard, start retard, and RPM limiter, nice to have. I also had switches that would not allow the system to work under 3,000 rpm and only at WOT along with a fuel pressure cut-off switch.
I honestly don't think you have a great combo for nitrous. It works best with lower compression and a tight cam. I am not sure you will see gains that justify the expense and possible problems.

ihengineer76

This is why I am getting your opinions. Having never used nitrous, I am not familiar with what compression, cam, etc. work well/poorly with it. The last thing I want to do right now is detonate a new motor. If I run the car and like it, I will probably just leave it alone for now. I don't have the desire to make it too quick anyway, since I don't want to put in a cage. Maybe I will just save the idea for the next project. This being a purpose built car set up for sub 11's.
Thanks much!

SBORule

The higher the compression ratio the better, when it comes to Nitrous but you have to do things so you don't blow head gaskets.

If I were running 10.75 to 1 compression, I would of selected a cam with more duration than the one you got to help ward off detonation. I would of went with something like 238/242 501"/501" with a 112-114 lobe separation.

That cam you got is going to cause detonation without Nitrous, I'd swap that thing out fast.

I only have 9.3 to 1 compression in my 355ci and my cam is 235/235 475"/475" with 113 lobe separation. My car doesn't have any issues with detonation running pump gas on motor but when I run Nitrous, I run 50/50 blend of 93 octane with Sunoco 110 I think it is, it's been awhile, it's the Purple gas.

That 3.42 gear is a perfect gear ratio for running NOS, find ya some 28" tall rear tires and you'll be running 11's no problem.

Hope you got a good torque convertor, one with anti balloon plates, this will help your engine stay together longer as well.

ihengineer76

The cam is 228 @.050 but advertised is 285. I am running 112 lsa. cutlassefi ground it for me and he was the one who helped me choose one to keep from having detonation problems. I am running a 2700 rpm stall 10" converter with anti balloon plate from PTC. Like I said before, my dynamic cr is 8.04 which should be fine for 93 octane. I also have polished combustion chambers and am running at 170 degrees for engine temp which help out as well. I am having no problems so far, but will keep a close eye on the motor for any signs of detonation.

BIGJERR

Heres a link to my old combo that lasted almost 9 years... the last 4-5 with nitrous......http://72.22.90.30/phpBB2/viewtopic.php?t=12112

Heres a video of one the coolest Oldsmobile nitrous purges you'll see(IMO) lol

Start slow and work your way up to the top setting.....FUEL AND FUEL PRESSURE is the key to making a motor live on nitrous......

When it was cool out I could run sub par gas but when it was hot out good fuel was mandatory......All I did was make passes and not bracket race on the NOS .........Iam sure NOS was the cause of my lost oil pressure after all those years beating on it......Well worth it to have a ten second Olds powered street car!

ihengineer76

I love the launch pic! Gotta love torque! There are no rice rockets that can twist like that!

BIGJERR

Dropping a 100HP shot right off the line on full throttle shows your weaknesses soon......My stock suspension was grossly overpowered,As you can see in that picture on the engine combo,That was My first sub 11second pass.....

ihengineer76

Did you end up back halfing the car or upgrade control arms and rear sway bar to flatten out the launch?

SBORule

I only use Nitrous in 2nd and 3rd gear and have run a best of 11.46 @ 123.11

I'd blow the tires off if I hit the Nitrous off the line, I need some slicks and Cal-Trac bars.

captjim

"Hope you got a good torque convertor, one with anti balloon plates, this will help your engine stay together longer as well"
I agree

"That 3.42 gear is a perfect gear ratio for running NOS"
I agree

"That cam you got is going to cause detonation without Nitrous"
I agree, that CR is just too much for a pump gas driver with iron heads, IMO.

"The higher the compression ratio the better, when it comes to Nitrous but you have to do things so you don't blow head gaskets."
This I do not agree with. IMO, nitrous is all about cylinder pressure. lower Crs with stock cams REALLY respond to a squirt. The more compression, bigger the cam, the less effective and more dangerous nitrous becomes. IMO.

BIGJERR

Front/rear drag shocks,Rear drag springs and UMI control arms and added a rear sway...

jfb

look buddy better head gaskets more fuel flowhelps but make sure if you do go bigger that everything can handle it front to rear i run 11.5 to 1 with a nitrous hit but i am built for it.