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094 | Tuning for Nitrous Oxide

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Hi there!

So sad I missed this Webinar but I just watched it and it's been very informative.

I've currently got a Toyota 86 running EcuTek and now a Borg Warner EFR 6758 (was running Sprintex). There is a Wet system by NX available to this car or a universal system. My question is if I use a wet system to add the fuel independently of the ECU, wouldn't the ECU read AFR's, not knowing what was really going on, and apply fuel trims to compensate for the suddenly rich AFR?

If tables have to be changed in the tune, wouldn't it be just as easy to run a dry system and let the ECU do all the fueling work? This is much easier with an aftermarket ECU but I'm not 100% sure with reflashing.

Also, my current tune is running Pure Speed Density through EcuTek custom maps (tune not done by myself). Would any fueling need to be changed in this tune in addition to timing?

Thanks!!

COO86L,

Although I haven't done this myself in this particular application I would assume using a wet kit would be better.

Reason I say this (And someone correct me if I am wrong or know there is a way to do it) if you're using a dry shot, when the NOS is activated you need the ECU to inject more fuel as required. On a stock ecu and ECUtek I don't think the capabilities are there to wire in a input to activated a secondary table for fueling, also how do you go about retarding ignition timing under NOS conditions as well but not under normal conditions?

As for the ECU changing trims to suit, if you're using NOS under wide open throttle conditions or under boost etc you should be able to adjust the closed loop to open loop conditions so the ECU will go to open over X TP or X Map etc. This will prevent any fuel trims upsetting things.

If running a wet system and set correctly the only thing in the ECU which would really need changing is the ignition timing. This could be tricky to do on a stock ecu and reflashing.

Hi guys,

With regards to tuning a dry nitrous kit on a turbocharged engine when the kit is triggered at a RPM that the engine would not normally be making boost pressure how would you approach tuning? In the webinar it was mentioned you add percentage of extra fuel based on the original fuel map in relation to the jet size in a NA application. Would you need to start at a very low jet size slowly working your way up achieving slightly more boost each jet increase while watching AFR's and adjusting accordingly? What are the recommendation for this type of tuning? Cheers Ryan

@COOL86 apologies I just saw your question. There's a variety of ways of going about this and not a strict 'right' or 'wrong' way. To add to what Chris has said, you're almost certainly going to be running the nitrous only at WOT and hence you'll be in open loop so the closed loop trims won't function. For this reason a wet kit will work well. You could also potentially use custom maps in the EcuTek software to run a dry kit if you desired - In fact you'll probably need to use custom maps to handle the ignition trims anyway.

@RyanN that's a great question. Generally you'll be starting from a well developed map for the engine running the turbo only and no nitrous. With this sort of map I tend to extrapolate my results out into the areas of the fuel and ignition tables I can't reach (ie low rpm/high boost) anyway to ensure a smooth and consistent shape to the tables. While the numbers you've put here might not be perfect, they're likely to be pretty close when you start adding nitrous and you can tweak them as required.

Now when you activate the nitrous, you have the option of making timing or fuelling changes in the main maps themselves (remembering these areas were inaccessible without nitrous), or your nitrous trim maps for fuel/ignition. I personally prefer to make these changes in my trim maps and leave the main tables untouched.

Hey guys,

Bringing back an old topic if you don't mind and it is not quite EFI related, but more on the plumbing side of a nitrous system.

My question is simply if you guys know any book or online resource, that I can use to gain some more knowledge on the tips and tricks, dos and don'ts when it comes to nitrous plumbing.

I am planning to have a direct port dry system installed on my STi and ran into a random forum post where somebody said a normal distribution block for example can be quite dangerous as the distribution of N2O will be unequal and pretty much unpredictable (compared to the a Y splitter), thus making a cylinder too lean or rich, potentially causing serious damage.

So this triggered me to try to read a bit more on the subject, but so far I only found articles that explain the difference between wet and dry systems, or something of that level, which is not much help for me.

Thanks a lot.

Keep searching and engage the applications engineers at the companies making the nitrous kits. For example, this article might be helpful:

https://www.nitroustech.com/blogs/tech/the-secret-formula-pounds-per-hour-and-flow-numbers