I was reading an old thread from 2004, but decided to make a new thread to ask about it.

I am considering putting in the LT4 knock module pretty soon, but read someone say don't get it if you run N2O, and some say they have no problems with N2O.

I run a 125 wet shot, and soon for a 150 and 175 after I get a tune, but will I run into any problems with the LT4 KM and N2O?

 

I ran between a 100-150 wet shot with it and didn't have any problems at all..

 

I've had friends running w/ the knock turned off in the tune w/o issues. Its going to come down to how well the set up is done. If you're doing it to get around rocker/header noise then you should be ok, if your doing it to mask random timing issues its a bad move.

 

I'm just installing it for performance and consistency since I have longtubes.

 

anyone else?

 

i ran a small 75 shot with the LT4 km and had no problems

 

Cool. Anyone used a 125 shot or higher? Somebody here has to have done it.

 

A nitrous tune should not be based of the knock sensor....it should not cause an issue just because it is the LT4 KM.

 

+1. What does N20 have to do with LT4 knock module?

 

I just read a few posts on an old thread that said "be careful with N2O on an LT4 KM because of how it pulls the timing"

Ok so I will be purchasing a LT4 module soon. Thanks for all the replies

 

You should not be relying on the knock sensor to pull timing if you go into detonation on spray, at that point it is to late.

You don't pull timing just to increase safety, it is done to get the combustion point at the correct place in the crank rotation.

Here is something I wrote up to answer a question on another board.

The reason you run a richer mixture is for a variety of reasons. The first is how combustion takes place in a nitrous motor is different than in a NA motor. Nitrous oxide does not burn, it is an oxidizer. It provides more oxygen, so more fuel can be burned, and the result is more power. The atoms in a nitrous oxide molecule are bonded together. At 565 degrees F, the bond is broken and the oxygen is then free. By adding nitrous oxide to an engine, the total amount of oxygen is increased and other gasses that do not support combustion (mostly nitrogen) are decreased. This speeds the burn rate and requires less timing advance for peak output. It is hard for many people to grasp gaining power with less timing, but it’s a fact. Peak cylinder pressure must occur approximately 20 degrees ATDC to make peak power. If you speed the burn rate, peak cylinder pressure will occur to soon. It is easy to run too much ignition advance with nitrous, but too much will not only hurt power, it can quickly bring a nitrous engine into detonation and destroy it.

This brings us to another reason you need more fuel in the cylinder. To keep the engine out of detonation, you must control the extra heat that nitrous makes. The easiest way to do this is to add more fuel. All nitrous systems come with rich jetting to give you a safe starting point. The extra fuel takes away heat and raises the detonation limit. If you don’t try to over do it, and keep the hp levels within reason, running slightly richer should be all you’ll need to control detonation. Running richer will both reduce the power output, but will raise the detonation limit to allow more nitrous to be used .

And last but not least "Atomization". You need a richer mixture to better the chances of the nitrous mixing with fuel. If a nitrous engine runs lean, it can destroy the engine in a matter of seconds. There must be enough fuel for the nitrous to react with, if there isn’t, temperatures rise rapidly. The oxygen that couldn’t react with fuel will oxidize any parts that get hot enough, and the next thing in line to burn is aluminum.

I will add one more thing to this discussion that is not A/F ratio based but will also help prevent detonation. RUN GOOD FUEL. You can have a correct A/F mixture, and have the right amount a timing advance but can still go into detonation if the octane rating is to low. I would never run nitrous with anything below 91-93 octane fuel, and as the shot size increases you will need to increase the overall octane rating of the fuel.

 

What deterred me is where it says "Not recommended for use with N20 or boost." on Summits site here: http://store.summitracing.com/partde...5&autoview=sku

 

its most likely their Lawyers talking

If you go into real detonation on the bottle, it will still work. The sensor can't tell if detonation is NA or power adder induced.

 

I ran a 125 with LT4 KM and didnt have any problems.
Untill I spun a bearing but that wasnt related to Knock it was to much HP through the stock short block and hundreds of drag strip runs.