I know that if you run NOS you need to retard 2 degrees per 50 HP shot. But where do you start? Do you retard from Zero or from your desired advance. I have my car advanted to 15 degrees, so do I retard 2 per 50 from there?

 

I'd set it at 10 for a 100 shot and go down with more than 100.(from past experiences)

 

That will work, NOS is coming and i defenatly want to be square on all the ins and outs before i learn the hardway.

THANX

 

You want to retard it at the total timing the motor sees when on the nitrous, meaning 3000 rpm up to shiftpoint. Now base timing adjustments on these EFI cars does change overall timing, so moving from 15 down to 10 would be ok for a 100 shot....but this depends.

Why is the motor at 15 base timing? What is the overall timing at peak rpm? 34-36? How are you tuning this motor?

Basically run the lowest amount of timing that still makes best hp/tq. So if all motor performance is peaked at 36 deg of timing, then use that as your base reference for nitrous. So for a 100shot, pull 4-5 deg atleast for an initial tune. So that will be 31-32 deg timing at peak rpms/loads.

You may find that the motor is ok with only 2 deg pulled. I only pulled 2 for a 150 shot on my 383 but I started tuning with 5 pulled and slowly added 1 each time and saw my ET/MPH increase.

 

On the NOS site they have a basic instruction tech manual to read. They say 2 deg per 50 HP plus 2 as a cushion when you begin. Plus coolder plugs, 93 octane, >3000 rpms for on etc.... I am on >3600 rpms today as my cam starts at 4000 rpms peak at 5800.

 

Ok, i understand. I set the car in the drive way at 15 degrees. I have not ran the car on a track yet but running around town it seems ok. 15 is just the base to start from. A friend told me to set the car at 2200 rpm and look at full advance, and the timing light said 28.5 degrees, but I'm not sure if 2200 was enough. My 383 has the ZZ4 cam and stock rebuilt L98 heads. Where should i be checking full advance, when the car stops pulling under load or ? I defenatly want to get this right, it would suck to blow the bottom out of the motor.

 

Is this carbed? what kind of distributor? mechanical advance, vacuum advance, or is it EFI TPI based?

If its carbed, just bring motor to 3000 rpm and look at timing tab. Generally want full timing of 34-36 deg in by 3000 rpm.

If its EFI, it needs tuned in the chip. Base has to match what the ecm has in the chip.

 

If stock is 6 deg and you are at 15 deg with the ESC connector to ECU unplugged when setting you would be 9 deg advanced from stock at all SA cells.

How did you arrive at 15 def initial timing?

Seems way to much timing.

 

Ok i got ya, I thought that 2200 was a bit low. Its TPI, i have put the hyper chip in it, i will have to dig up the paper work and see what it says for the base in the chip. So basically match the base with what the chip recommends and then back off from there?

 

Where is the ESC connector located, cause no it was not unplugged. This is my first fuel injected toy, i have always ran carbs. So I am learning how this EFI stuff works.

 

Base is mechanical timing with ECM disconnected from dizzy. Base = initial timing. With ESC plug connected the base-initial(6 d adv) goes to what the ECU shows for that idle RPM/MAP(maybe 20deg?). Connector is near brake booster a tan plug. Always disconnect to set base and dont forget to reconnect when done. You may need to disconnect battery to clear code when done.

 

He is correct, but you won't have to disconnect the battery to clear the code.

With a hypertech in there(it advances the timing). I'd start around 6* initial(stock setting) with the brown wire disconnected. Then plug it up and go to 3k and let us know what it is.


Although I did get away with a hypertech and 12* timing for a LONG time, I don't recommend it

 

Ok cool, so whatever you set the base mechanical at, when you plug in the ESC it adds 6 more degrees, so I have probably got it to far right now. Now does the after market chips affect the base by much, its a hypertech from summit?

 

I will do that, it maybe over the weekend but i will let you know.

 

Exactly. Theres no magical number. Ive found it best to simply pull more timing then what is suggested(rule of thumb 2* per 50),and tune from there.

NOS recommends not pulling timing at 150 shot. BUT, if it were me and my engine, id pull more timing, and slowly work my way up, if the engine starts to see spark knock etc, adjust from there, if not, keep it moving. Just know, the timing will never truly be the same because of weather and other factors you cant control, so i play it safe.

In short.

Pull more, go up from there, and i always shoot to make the most power on the rich side. Just not too rich

 

Hey, what's up with that brand Nitrous Xpress? the kit for Efi cars states that no timing retards or additional fuel is needed? Anyone know?

 

That's a real general statement. You need to keep in mind you need to run colder plugs and have the fueling capabilities to go with whatever shot your running. I always recommend pulling timining on the first spray as well. As running it a tad rich. You need the proper datalogging and tuning equipment and ability as well.

You might get away with not pulling timing on a real small shot with the right tuning but for how long? Every engines different and really acts different based on weather, running condition etc.

Just be careful,read what the manufacturers suggest and use common sense.

Nx has some decent kits