Which is more important when using nitrous, to buy an ignition box with rev limiter first or to buy a window switch. Don't have the money for both now and I am looking at this from a safety standpoint of not hitting the factory rev limiter when on nitrous. I haven't gone over 100 shot yet, so which would be better to buy first?

 

rev limiter absolutely.

 

Wow, I was reading this, thinking "window switch absolutely", then I read your follow-up

With a window switch you not only get a way to shut off your nitrous before the rev limit, but you get the low end limit to protect you from bog. The only thing you don't have is the stronger ignition spark that nitrous can use, which may or may not end up being a problem, but wouldn't be a safety issue.

Right, or am I missing something?

Dave

 

if the window switch fails---boom. same could be said for the ignition rev limiter but i would trust the ignition rev limiter first. I've had the window switch go bad and was saved by the ignition limiter. the nitrous will also like the hotter spark for the ignition box. but you do make a good point about the bog. I never really had a problem with that but i have seen some who have.

 

I'm with Dave. I'd look at the window switch first. Hopefully you can raise your rev limiter from the factory, have the Window switch cut the Nitrous somewhere BETWEEN the shift point and Rev Limiter. If you don't like the idea of shifting on the spray thats fine too, but the Window switch is less money and wll get mroe accomplished that you actually need.

The increased Spark intensity is nice, but not neccessary IMO at this point.

Good luck!

 

Okay, sounds reasonable. I haven't seen a window switch go bad, but it seems they do.

Dave

 

I will also agree to the window switch over the ignition. Most guys wont spray through the shift with a stock auto,and 6 speed guys usually dont.
The rev limiter would be nice,but not needed yet especially with the 100 shot.
I have never heard of a window switch going bad,but anything is possible with electronics..............BTW i did a MSD Digital 6 take a crap on me,1 day it just locked the rev limiter down to 3400 rpm.

 

I was leaning towards the window switch too. I will most likely end up with the ignition box down the road. It just seemed to me that they were both accomplishing my goal, just in two different ways. I just wanted other opinions. Does this make sense to have both of them down the road?

 

IF the window switch fails and you hit the oem rev limiter, your buying pistons at least. You could buy the Mallory box that has rev limit and window switch built in.

 

The factory limiter cuts fuel, which is concern with a blower but not a wet nitrous system. Think about it. You are still injecting nitrous and fuel in the correct proportions. Of course, you don't want to hit any rev limiter with the nitrous on. That's why you need a window switch. But an aftermarket ignition limiter will not be any better in this regard than the OEM limiter AFAIK. You will still build up nitrous in the intake with a possible "bang" if you hit the rev limiter with the N2O activated. And if you have an automatic, it's preferable to turn the nitrous during shifts. Again, another point in favor of the window switch.

At the other end of the rev range, spraying at too low an rpm is a major cause of nitrous induced engine damage. So all in all, I wouldn't use nitrous without a window switch.

Rich Krause

 

So when I hit the oem limiter and the injecters shut down it well not go lean....think about it. You just bought pistons.

 

Heres my take:

Steve: You're right Once the fuel from the EFI system is pulled back, the engine still has the ability to pull vacuum, will pull the Nitrous/Fuel Mix from the N20 system in, and could be on the lean side. Take note this did happen to me at one time in Mission. After the pass the car was still running great, and after that made the fastest pass it had to date. This year after pulling the engine apart the pistons were just fine. NOT something I'd recommend, but I wouldn't say "You're buying pistons at least"

Rich: Maybe its the way your wording didn't come across correctly, but obviously for everyone else the Nitrous still enters the cylinder weather an OEM Fuel Cutoff or Aftermarket Ignition Cutoff Limiter comes in.

Heres the problem. in ANY rev limiter. We just went over what happens with a fuel limiter, but in a Spark Cutoff there is a different issue.

Considering that in a Spark Limiter most companies pull the spark from cylinder 1,3,5,7, on one cycle, and 2,4,6,8 on the next. These cylinders are basically dead. None of the Air/Nitrous/Fuel Mixture is being burnt, however alot of it will stay behind for the next cycle (Granted alot of it is going out the exhaust also, depending on your cam profile). Once the next revolution comes around and spark is added your 150 shot could turn into a 250 shot due to the leftover Nitrous that wasn't scavenged from the exhaust.

We had this happen a couple of times in a 340ci Duster w/ a 250hp plate. Luckily our Engine was well built and it went through the headgasket before the piston.

Stuff breaks. It happens. I don't know how many ignition boxes I've had go out. Honestly the BEST box I've ever had is the Crane Hi6-TR in the Camaro. 4 years and ZERO problems. I've had MSD 6A, AL, MSD 7AL2 All Burn up. I just got my Digital 7 back from MSD for repairs, cuz I bought it 2nd hand cheap because it was fragged. Don't even get me started on Mallory.

Personally I'd rather not hit the rev limiter at all. Either one can be bad news. Get the window switch, and your problems are solved unless the unit goes out, which in the end, I think these units work more often then they don't right?

Sorry for the Book.

 

Kurt is right. I wasn't thinking clearly when I posted (well, in my defense note the time!). You don't want to hit any rev limiter, like he said. I was trying to get across exactly that - it will be equally bad if it's an ignition or a fuel based limiter, just in a different way.

You need a window switch if you are going to run nitrous.

Rich Krause

 

Thats the best option...one ignition box that has what you want plus retard option also.

 

Yeah, uh huh, sure, whatever you say Rich. everyone ha an excuse. hehe

-K