Nitrous Oxide Questions

[Guest Z2nr]

I have been tuning cars for a while but I have not done too much research on N20. I know how it works and all, but are there any adverse affects on the engine that nitrous produces?

 

A lot of people are scared of it, but I beleive they are scared of what they don't understand. Is it true that nitrous actually leaves a sediment or some kind of film or byproduct in your combustion chamber, if so is there a way to clean it out like with water injection or something.

 

Thanx for your help!

[Guest Magnum Rockwilder]

Nitrous actually CLEANS the combustion chambers.

 

Adverse effects would have to be:

 

risk of burning rings or valves if something goes wrong and leans out the mixture

 

increased ring wear

 

increased valve guide wear

 

increased bearing wear from increased load

 

I'll type more later... pizza time.

[Guest Magnum Rockwilder]

Okay, nitrous is fine as long as you use an appropriately sized "shot" for your engine. You also need to install more than just the basic system to be 100% safe. I would recommend a low fuel pressure shutoff switch, window switch, bottle heater, and preferably a progressive controller. All of those will eliminate variables and make for a more consistant and safer setup.

 

You can EASILY install a small shot like 50hp and spray it all you want with no preparation or problems, and a 75 shot will be fine with minor preparations. You can run up to a 150 shot on an L series with some decent nitrous-specific prep work. I have a fully N2O-prepped E88 head for sale for $150. It has polished combustion chambers, enlarged ports, and a valve job.

 

I can tell you everything you need to know about N2O if you decide for sure you want to spray. First step is buy a kit, then start buying the add-ons and doing the prep work.

 

You'll need a 6 fogger direct port system... around $700 new. I have one that I bought for $350 brand new from a guy who bought it and decided it was too hard to install.

[Guest Z2nr]

I am really considering building a NOS rocket out a 71z. I will be using the l24 motor probably. I have not bought the car yet, but will be in early Janruary.

 

I would like to purchase a kit and add-ons now if possible. What is the best nitrous kit on the market that you recommend. I heard nitrous express is good. As far as add-ons I know what a bottle heater and window switch is by the way who makes a good window switch I heard MSD does. I have no idea what the other things are like the low fuel pressure shutoff switch, and a progressive controller. I will do some more research on those things, I just would like product recommendations I would like a solid nitrous kit for my Z.

 

I will be rebuilding the motor with forged pistons and rods, since it's pretty cheap to do. I will be looking into squeezing like 120 shot, I am getting the internals for insurance, what about the tranny will it hold up to this power, I probably will be using a centerforce II clutch.

 

Thanx for your help bro.

[Guest Magnum Rockwilder]

You don't need to replace the bottom end with forged stuff. Just pay a little attention to the head. I'll tell you exactly what to do with the head later tonight, and I'll also find you some nitrous kits that would work and explain the progressive controller and other safeguards more. Right now I have some errands to run. I'll be back on late tonight.

[Guest Z2nr]

I did more research on some of the add-ons, the progressive nitrous controller is cool, basically it allows a more controlled injection of nitrous to reduce engine and drive train shock as well as reducing wheel spin for better e.t.'s.

 

I want to at least rebuild the engine even if I don't go forged, I personally don't think it's safe to run 120 hp shot on a stock un-opened 30yr old motor, just seems a little risky to me.

 

I definitely want to run a direct port with a window switch and a progressive controller. What rpm should I start and stop the nitrous, I was thinking like 5k to like 6800.

 

What should I upgrade on the engine as far as head and bolt-ons. I am thinking that maybe the stock carbs may not be up to the task of an extra 120whp, but I am going to keep researching. Is it possible to convert the carb setup efi? The price of an upgraded carbs are like 1200 and up, converting to efi would be safer and probably less costly possibly.

 

I just want to do something for now. I will be swapping in an Sr20det in a year or so when I leave SoCal. If I swap the engine here, with the popularity of drifting in SoCal people will be trying to steal my Z once they find out it's Sr powered since the whole Silvia thing has just recently blown up now because of the sport.

 

Any how I really need to discuss what block, head and drivetrain modications are necessary to properly harness this power without breaking stuff left and right. By the way this car will be my daily until I move.

[Guest Magnum Rockwilder]

I just got home and I'm tired as hell, but I'll type a little and then follow up tomorrow.

 

If you want to freshen the engine, do a compression check. If it's in spec, you may want to just leave it alone. If it's out of spec, pull the head and measure the bores. If they're within spec, install new rings and hone the cylinders to break the rings in. Pull the oil pan and check the bearings. If they're out of spec, replace them. If you want to go nuts, you can smooth and shot peen the rods, but it's unnecessary with a 120 shot. These engines can handle quite a bit of power.

 

For the head, studs are recommended if you can swing it, but again, not necessary. They replace the head bolts with studs and nuts, and do a better job of sealing the head down.

 

Take a grinder or dremel and grind down any skarp edges in the combustion chambers. You want everything to be smooth. Sharp thin edges heat up until they're glowing and can cause preignition (knock). Remove and reseat the valves with grinding compound, and install new valve seals. Install the head with a new gasket and torque it down 5-10lbs more than stock. Set the valve on the loose end of the spec.

 

Retard the cam timing.

 

Run an electronic distributor, with the vacuum advance disabled and the timing retarded a few degrees.

 

An MSD ignition is a good idea, but not required.

 

Run copper plugs gapped down to around .030. File the tips of the ground electrodes smooth so there are no sharp edges. This is the number one meltdown point on a nitrous motor.

 

Get rid of the muffler and install either straight piping or at most a "race muffler", install a header. You HAVE to let the engine breathe.

 

The stock cars should be fine, but ditch the stock air filter and install a K&N, or to go the cheap routem remove the airbox lid and install UNI motorcycle air filter foam over the velocity stacks.

 

Richen the carbs a little.

 

You'll need a ZX 5spd tranny, and I'd stick with relatively weak clutches, because that way if anything gives it'll be the clutch and not a gearset or input shaft.

 

With a progressive controller, you can start spraying as low as 3000rpm, but you'll want to stick with a small shot and ramp it up to full spray no sooner than 5k rpm. You can store 11 programs in the NX progressive controller.

 

You don't want a sudden hit, because that's what breaks rods. Also, nitrous creates more torque in the lower rpms, so a 50 shot might only make 50 peak HP, but it'll make 100 extra lb/ft at 2500rpm if you spray it that low.

 

I'll typre more tomorrow.

[Guest ON3GO]

i dont think a 6 port direct port system is really needed.. not for a street car atleast.

a simple fogger system will do fine.

ill be running a fogger wet kit on the green Z once time comes and in a shot of 100-150...

 

mike

[Guest Magnum Rockwilder]

So where's he gonna put a single fogger on a dual carb motor?

[Guest ON3GO]

So where's he gonna put a single fogger on a dual carb motor?

ahh didnt see that...

[ZHeadV8]

Fascinating stuff Magnum,

 

Am in the process of having an Edelbrock Performer SBC put into a 1971 240Z and have been advised to go for the 420BHP option potentially with nitrous as opposed to a stroked 500BHP option without. The guys that seem to know are telling me 500BHP all the time will be too much in a 2300lb car .......

 

Can't see why but they have built and run these things before so I trust their experience and judgement. Do you have any views on nitrous and V8s ?

 

Cheers

 

Andy

[Guest Magnum Rockwilder]

I agree that a milder engine with a 100-150hp shot for the occasional race is better than a balls-out motor. It'll live a lot longer and be more fun to drive on a daily basis.

 

With a SBC, you can get a plate system that goes under the carb. They can be had for as cheap as $375 new (NOS Sniper).

 

An all-cast SBC can easily handle a 100-125hp shot with no other preparation, and with a little prep work they can take a 150 shot. With forged internals and a torque converter with an anti-balloon plate, you can spray up to 250hp.

 

Mpst people who build a radical 500hp small block for the street end up not enjoying it as much as if they had tamed it down a bit, and nitrous is "The Great Equalizer" and can turn a mild 350hp engine into a 600 lb/ft beast at the flip of a switch.

 

I'd recommend a 400hp engine with a 100-125hp shot on top of it. I'd also recommend using a larger bottle than the typical 10 pounder, because refilling them is a bitch.

 

One 20lb bottle is a couple pounds lighter and easier to plumb that two 10lb bottles... if you don't mind a 2 foot long bottle in your hatch.

[ZHeadV8]

Hi Magnum,

 

Since the last question things have turned sharp left. I have had some great helpful advice from Mike and other forum members on whether to use the Edelbrock old school SBC or a newer computer controlled one and there was a resounding "don't be a muppet, get an LS6" so that is what I am going to do.

 

As the LS6 puts out 400BHP ish that should be enough for everyday use, is an LS6 strong enough to cope with N2O without much internal work ?? Would only use it occasionally on track days or drag runs.

 

HAPPY NEW YEAR

 

Andy F

[Guest Magnum Rockwilder]

NOS recommends a 125hp shot of nitrous for a stock LS1 or LS6.

[ZHeadV8]

Cool, so I put a 125BHP shot into the motor and what happens ? I know I get more HP but what about the torque ? What does it do to the engine ? I have heard scare stories of each shot takes x amount of miles off the life, you need to rebuild every x amount of miles.

 

What is the truth here please ? If there is no damage to the engine it is a done deal - if it means a rebuild every 10K miles then I will have to think seriously.

 

Thanks for such a prompt reply to the last question

[Guest Magnum Rockwilder]

A 125hp shot of nitrous adds about 125whp and 150+wtq. A wet shot will add more torque than a dry shot, but the readily available kit for an LS (NOS #5177) is a dry shot... not to mention spraying fuel into a "dry" manifold isn't a good idea. They aren't designed to flow liquid, and puddles can form... BOOM!

 

If you want to go over a 125 shot, install direct port... but I think you'll be happy with 125hp. That'll drop a full second off your quarter if you can put it to the ground.

 

I would set up a 125 shot to spray from 4000rpm-6500rpm... a hundred rpm before the rev limiter. The lower the rpm you spray, the more torque is added, and stock rods/bolts don't react too well to 600tq at 2000rpm.

 

If you hit the limiter on spray, you'll never do it again.

 

I'd recommend that you join LS1.com and check out what they have to say about spray. I know a lot of guys over there have been spraying for a while, so it's a good source.

[Guest Magnum Rockwilder]

The engine WILL see accelerated wear as far as the rings and valves due to the increased heat and pressure, and the rod bearings will see more pressure and will likely wear quicker, but we're talking about something that you'd never know if I didn't tell you. Hypothetically, let's say that if a typical N/A LS lasts 150k miles before it needs a rebuild, one that gulps nitrous every other weekend for its whole life will make it 135k miles... this is strictly unscientific opinion, though... and educated guess.

 

Barring catastrophic events, a motor can live a long life on nitrous. My last nitrous motor went 140k miles and only had one problem: a burnt valve from my window switch failing and me hitting the rev limiter with a 150hp shot spraying. I melted one valve and toasted the other 23. I put the motor back together with a new $20 valve, and reused the old head gasket, and continued to spray until I wrecked the car. It still had good compression and the only maintenance I did was change the rod bearings at 100k miles because they were showing copper.

 

You'll break rear ends and trannies before you break your motor.

[ZHeadV8]

Thanks - a rebuild every 100K+ is nothing for a seriously powerful engine, try running an EVO VIII or a Subaru Impreza that have been tuned to 500BHP and see what they require !

 

Will join LS1.com and read up, thanks for the pointer

 

Cheers

 

Andy F