retarding timing with nitrous

What do you guys use to retard the timing for nitrous? I have tunercat, but have yet to learn to use it. I still have 5deg of knock that is mysteriously only while on the gas or at idle, so I am trying to fix that of course first. I have talked to some people and what I am hearing is to straight pull the timing in the tune instead of using an ignition box setup? Any one have luck w/ an ignition box or the tunercat?

thanks

I am using a MSD Digital 6 to retard the timing on my 94....used to pull 2-3* when it was H/C/150shot and I am now pulling 8* on the current 200 shot...no issues as of yet.

With pulling it with a tune you will be pulling it all the time and the car wont run as well NA. With a box you will just be retarding when you are on spray. IMO this is the definate way to go. I am running the Mallory 685 ignition box and pulling 5ish i believe

Yes, it would be pulling it all the time, if I didn't have my laptop with me. Since I have my laptop I can run to the track on my normal tune, and do nothing to the tune except change the timing (-whatever degrees for 100shot, maybe 2deg?) and then that is my nitrous tune for at the track. This is what I was thinking about... still not sure.

Yes, it would be pulling it all the time, if I didn't have my laptop with me. Since I have my laptop I can run to the track on my normal tune, and do nothing to the tune except change the timing (-whatever degrees for 100shot, maybe 2deg?) and then that is my nitrous tune for at the track. This is what I was thinking about... still not sure.

Until you get the urge to show the rice whats what on the street and you have the street tune in there :D

Until you get the urge to show the rice whats what on the street and you have the street tune in there :D

Or when you want to make a pass N/A and run slower because your on the nitrous tune.
Ignition box is the way to go, if your bottles full and warm your ALWAYS ready.

Thanks guys for all the info, it is looking like the ignition box path will prevail. Very good points. How many degrees again? I have heard 2-3deg for every 50hp pill? So 5deg for 100shot?

every car will be different but 1-2 per 50 is the normal starting point....I am pulling 8* for a 200

How much can you pull with the Mallory 685? I was under the impression that 4 was the most this box would pull. Is this wrong, I hope so, then I will throw in the 150 jets.

mallory 685 here. i love the box its badass.

my dynotuner was aware i would be spraying, after tuning the car in, he pulled 4 degrees and there was no drop in n/a performance, so he told me not to pull any more timing, i still pull 2 degrees with a 125 shot through the mallory and so far its awesome.

I can pull up to 15 degrees with my mallory box and if you wire it right it will only pull timing when the nitrous is activated. I love my mallory box.

I can pull up to 15 degrees with my mallory box and if you wire it right it will only pull timing when the nitrous is activated. I love my mallory box.

mhmmmm.

I'm using the Mallory box as well, another handy feature it comes with is also a window switch. Its a pretty good bang for the buck.

i've noticed with the msd boxes there are variations of msd 6a's
what exact version? looking to run a 100 shot

dont kno if they make one for a lt car but i use a msd timing twister only takes timing out when spraying.

keep em coming
ty evan

im running a mallory 685 also and love it... i spray a 300 shot, and log every time that switch is on with my laptop.

i've noticed with the msd boxes there are variations of msd 6a's
what exact version? looking to run a 100 shot

The digital6 is the one with internal timing retard...with the 6a or the 6al, you will need to add a seperate retard module....works out to be about the same price as the digital6

im running a mallory 685 also and love it... i spray a 300 shot, and log every time that switch is on with my laptop.

What software do you run on your laptop? What all does it record?

mallory 685 is the best box invented u can pull timing as the nitrous hits and it has the built in window switch and more stuff i dont use lol!! I have the msd coil, but msd does not have box that includes what the 685 does all in one! u just have to get the harness plug that allows u to wire it up and it makes it a piece of cake!

The only way to tell how much timing you should pull is with testing, preferably on a dyno but the track will do. Small amounts of nitrous may not need any retard, depending on where your timing is set in the first place. On an LT1, stock timing is aggressive abd probably will need some retard.

rich

I may be retarded, but now I have to look over my wiring to make sure I did it right and it only pulls timing when it is spraying ...

I actually dont run my box until I am ready to make an N20 run. I use the bypass connector most of the time since some people were having longevity issues with Mallorys that overheated. I mounted mine in the glove box, and felt the only proper way to keep it cool is to use it only when I am spraying. So far so good, and it seems to be a high quality set up. I was a little disapointed with the wiring directions though, WTF ???

I run the digi 6 and have it retard the timing only when the solenoids are energized..

If the mallory is similiar to the digi 6 you just take your 12v that activate your solenoids and run it to the correct wire on the mallory.

I use Nitro Dave's digital window switch which I am very pleased with. Really like the lock out 1st gear option...

Cody

I may be retarded, but now I have to look over my wiring to make sure I did it right and it only pulls timing when it is spraying ...

I actually dont run my box until I am ready to make an N20 run. I use the bypass connector most of the time since some people were having longevity issues with Mallorys that overheated. I mounted mine in the glove box, and felt the only proper way to keep it cool is to use it only when I am spraying. So far so good, and it seems to be a high quality set up. I was a little disapointed with the wiring directions though, WTF ???


How do you have a bypass connector setup? That sounds like a good idea to help with the overheating and longevity problems.

It comes with a bypass connector that you can plug in instead of having the ignition wires running through the box. It all comes with the Mallory 685 box.

Really simple to use though. You just unplug the connector from the pigtail coming off of the ignition box, and plug it into the by-pass connector ( Which basically is just 2 wires that loop around, with the proper end on it to plug right into the connector), and your done. The car has to be turned off to do it. But it takes about 20 seconds. If it didn't come with the by-pass connector, I probably never would have mounted the box in my glovebox, but its fast, easy, and a simple solution to the overheating/longevity issues.

Feel free to shoot me an email or anything if you have any more questions though.

I have the msd digital 7 programable box it has so many retards its retarded :D
start retard,launch retard,a retard for each gear,boost retard and every one of them can be ramped. I plan to run a 150 shot next year I guess I will start with 5-6 degrees and see how it likes it

Rock ~ Never realized that a digital 7 can do all that. The mallory does Start Retard, window switch, boost retard (Which can be ramped per PSI), rev limiter, two-step, and a couple other small things I am forgetting about ???

Definatly does NOT have a retard for each gear though.

hmm how you guys pulling timing with the mallory 685...had mine a few yrs now and lost the books.... someone tell me how?

If you monitor the burst knock when engaging nitrous you will see the pcm spark retard automatically in progress. I was asking about placing a longer nitrous line (longer than the fuel line) to the fogger in an attempt to eliminate this moment of knock. A speed shop tuner told me not to bother with a longer line or even spark retard on a 100 hp (or so) shot. He told me that when they tune engines for nitrous in that range, they just use the momentary knock timing retard as the adjustment for spark timing. They have found no value in a longer nitrous line or reducing timing a few degrees. It is just taking away more power. The pcm has already done its job and the additional timing retard for 100 or so hp is a waste. I'm not saying he is right.

hmm how you guys pulling timing with the mallory 685...had mine a few yrs now and lost the books.... someone tell me how?
Go here: http://www.malloryperformance.com/pdf/685_6851.pdf

See page 10

You need to experiment with your particular combo. But it is well known that the burn speed of a fuel air mixture plus nitrous increases. So, if your timing was optimal in the first place, it will be too advanced when nitrous is added and pulling back timing usually INCREASES power, not decreases it as suggested by 01Z. The stock timing curve on both the LT1 and LS motors is pretty aggressive. GM puts a lot faith in the knock sensor to protect from detonation. Adding nitorus does not cause detonation - it causes a quicker burn and increases cylinder pressures. This MAY be picked up by the knock sensor as knock (the KS is an acoustic pickup) but I wouldn't count on it. I do not agree with the above suggestion, I think it gives up "free" hp.

Rich

I do not agree with the above suggestion, I think it gives up "free" hp.

Rich

You didn't get my point at all.

You didn't get my point at all.

Elaborate?

Rich

Since it's you.... :cool:

In my parting sentence I wrote "I'm not saying he is right" as my disclaimer so at least part of my point is not a suggestion but a regurgitation from someone from some place that would surprise you. I regurgitate because I have no authority and little experience.

My point is about the pesky initial knock count that in some installations occurs without exception when the nitrous first hits and not about overall timing under nitrous; the inference is being taken wrong because I had diverted to solving a problem which has the side benefit of causing timing to be automatically pulled.

As I'm sure you know, when the PCM pulls timing it gives it back slowly. So in essence what the speed shop tech, who is also a successful manufacturer and seller of excellent products told me they use that initial timing retard as an automatic method of setting timing back under light shots of nitrous. Not everyone is unlucky and gets this first hit knock count. But in some situations this particular tuner cannot solve that problem so they use it to their advantage.

In other words, sometimes we can pull away too much spark advance even under nitrous and thereby forfeit some level of performance. That is what I took from what he said when I asked about adding a length of nitrous line to insure that the faster-than-petrol moving liquid n2o does not create an initial lean condition that causes knock that causes the pcm to pull up to 15 degrees of timing. So, my point is about timing already being pulled and then a device that pulls even more - hence too much timing being pulled.

If you don't have this initial burst of knock then pulling timing is a good and safe thing. If you consistently get this brief moment of knock then pulling even more timing is diminishing performance.

IMHO all nitrous installs should be monitored for knock and watched with a logged wideband but first timers usually start with just the nitrous and sometimes move on to worry about really getting the timing right. I'm :tired: and I'm :leaving:

:) Thanks, I see a bit better now what you meant. The issue with timing and N2O isn't detonation so much as power though. You potentially leave power on the table by not retarding the timing. Since the burn is faster, peak cylinder pressure appears too soon w/nitrous and power is lost. The peak cylinder pressure also may be very high, damaging parts in a way very similar to detonation.

Rich

Okay, I learned something new here - thanks for explaining. Timing retard isn't just for detonation, got it now.

Oh and another thing your explanation illuminates. I have been talking with a tuner that charges an extra $100 for nitrous. To me this seemed unnecessary because I can do that myself. However, if he is experimenting with the correct amount of spark retardation in order to increase the power effect then that tells me he would tweak in the correct timing in order to get the full blow from the hit rather than just keeping the engine from hammering itself. Thanks again man!