NITROUS OXIDE ( nos / n2o ) advice forum

Continuing on from where I left off....

Can't wait for this one!!!

did someone mention bmw what is it

So!
You are back in the saddle again.

Your last setup was a work of art for sure. Good luck with the new project.
Perry

Excellent - Glad to hear your still carrying on.

Thanks guys.

This system didn't just "start" now, it's been in the planning stages as far back as last fall. (After the incident) Trev and I have probably traded a 200+ emails on technical details alone, and we started on nitrous specific parts last February.

This will not be a REVO system initially, although I certainly pursued that option for a very long time. The deciding factor on the "valve" type came down to fuel control, and my own beliefs of what will work on my new manifold.

The new manifold is intentionally undersized for the airflow required by the engine, but has state of the air runner design and materials that I believe will be a significant benefit when using nitrous. This was also started last fall, and I probably won't see the piece in person until mid-summer due to modifications being made, and then it's use by the head guru in finishing port work. Probably the most effective design characteristic of this manifold is that the runners are made of Carbon Fiber, and shaped in an extremely organic nature to take advantage of certain airflow principles. If you wanted to fill a tube with something cold, and keep it cold, Carbon fiber I believe is the way to go....

It will not be a DRY system, although that option was certainly pursued to a great extent as well. Using EFI has huge tuning advantages, especially with a constant flow of nitrous, but in the end I found issues with "mixture preparation" that made me seriously reconsider a properly installed wet system. If you are going to chop the nitrous charge into pieces, (pulsing) it will be utilized a lot more efficiently if the fuel mixture is correct in every one of these pieces. I'll get into this in more detail in the future.

The nitrous control strategy is still undecided. On one side, the Max Extreme controller offers a lot of easy to use features. On the other, dedicated stand alone ECUs from Motec and Pectel offer the ability to build complex control strategies that are a bit outside of the Max Extreme's abilities at this point. For example, progressive ramps for each gear based on engine RPM. This would allow you to flat-line the torque curve for each gear to compensate for the reduction in gear ratio. As an example, first gear could be limited to 300 lb/ft from 4000-8000 RPM, second gear would have 400 lb/ft from 4500-8000 RPM, 3rd gear would have 550 lb/ft from 5000-8000 RPM. Basically, the force applied to the tire could be made equal in each gear to maximize traction. When you run an automatic transmission, a time based progressive control would be best, but for a 5 speed manual with a clutch ,RPM based progressive strategy offers more control. Also, it's extremely difficult to do spark control strategies on the dyno with a time based nitrous strategy when the engine control ECU is running RPM based strategy.

Another control option that I see being critical for a high flowing progressive system is independent nitrous and fuel progressive curves. The fuel and nitrous pulsoids may respond very similar on a test bench, but when you add all the pipework and jetting of a finished installation, things start to shift a bit. From a flow perspective, you may actually find the following:

Input Signal Nitrous Flow Fuel Flow
25% 30% 25%
50% 58% 48%
75% 73% 73%

Doesn't seem like a big difference, but lets scale that to say 600hp flow potential:

Input Signal Nitrous Flow Fuel Flow
25% 180hp 150hp
50% 348hp 288hp
75% 438hp 438hp

I experienced something similar to this on the dyno with my previous system, where I had optimum AFRs at 100%, but slightly leaner AFRs in the middle of the progressive range. The Max Extreme controller offers a fuel offset feature where you can increase or subtract duty cycle from the fuel side by a set percent. But this percent is uniform across the entire range of progression. Adding 5% fuel means you get 30% at 25%, and 80% at 75%. It literally is an "offset" feature that shifts the AFRs when progressing. The next step in progressive control is to have an independent trim table for both the nitrous and fuel outputs that matches the actual nitrous and fuel flow to the desired input signal at all points in the adjustment range. Using the above numbers as an example, having the nitrous pulsoid run 5% less at 25% input, and 8% less at 50% input. This is possible with PWM tables on both Pectel and Motec ECUs, and I've built the control strategies to do this on my laptop. What would be great is if the Max Extreme could do this, because a 10% difference in flow at 600 or 900hp is pretty big.

Then there's the new engine, which is turning into quite an R&D project in itself....

WOW sound great

on the fule side , you said the A/f was richer at 100% power , not for this project as you seam to have most things covered , but could you tune an engin to the slightly leaner A/F of mid range and just set the Max to 80 % and just use a bigger jet to get you overall power , so never run the pulsed system at 100%

Respect


Tezz

Tezz,

I plan to move well beyond theory, and work through the tuning on the flow bench before anything gets bolted to the engine. It will be a lot easier to explain some of my ideas, and the solutions, with the data I'm seeking.

There are a number of limiting factors to pulsing that I want to understand a LOT better. Trev knows where I'm going with this, and I'm sure he's just as excited as I am to see the results. Rather than looking at trends, which can be very useful, I'm going to try and isolate specific events and "record" them in great detail. There are 3 tools for this: A data logger that samples at 1000hz, a high speed video camera, and a high resolution "macro" photography setup.

Regarding the comment on bigger jets: The limitation of the system will not be the jetting, but elseware. This is something that Trev and his team are currently working on for my project, and I suspect will be made available to the general public shortly after.

There were 5 different system ideas that I worked through since the fall. Most have been discussed on this forum in some place or another, but one I've only hinted at with Trev. We seem to be on the same wavelength with it despite both of us neglecting to get into any details.

That was a suggestion from Loopy,quite a while ago.
Now many of us are using wideband O2 we are seeing what goes on during progression.
It would seem that afr during pulsing is leaner than that at wide open flow.Even without wideband it can be picked up on a static test,revs increase at first then flatten out as pulsoids max out.Not a massive problem though,I guess it's just not maximum efficiency.

Loopy's suggestion made sense,I believe it was a strategy that he used himself.


Another interesting thread/build...please no fires this time

I know someone using carbon runners and plenum..na. getting very favourable results.

Wideband is still a lagging indicator.

When flowing the kind of #s I'm looking for, leaving 20% on the table is really expensive and doesn't lend itself to system efficiency. You'd have to make things even bigger to hit the flow number, which negates a number of design principles regarding nitrous density.

I'm installing pressure sensors in the combustion chambers. You'll be able to SEE individual combustion events, and using the analysis software, determine how much fuel is being burned, how fast, and what the burn efficiency is.

With Motec or Pectel, we can time the phasing between the nitrous and fuel injection pulsoids. I'm not talking about varying duty cycle, I'm talking about varying the injection start time. We'll be able to tune this watching the burn pressure trace.

Getting a little bit off topic, I'll also be able to tune the cam timing in increments of 0.5 degrees while the engine is running. There can be a different cam position based on load (how much nitrous is being injected) and RPM. Normally on an N/A engine, the IVO and IVC are critical. On a nitrous engine, the EVO and EVC become more critical. With the BMW valve timing system, I can tune both in real time. (40 degrees of adjustment for intake, and 25 degrees of adjustment for exhaust) In real world terms, this means being able to move the intake centerline from 80 deg ATDC to 125 deg ATDC, and exhaust centerline from 115 deg BTDC to 90 deg BTDC.

I usually read everything and rarely post but what i`ve read in this thread so far deserves a :

DAMN ! You`re one intense guy !

WOW that is going to be one hell of an exciting project.

I said a while ago that the only way to find out what was really going on with nitrous would be in cylinder pressure sensors...and now someone is actually going to do it.

I cannot wait for more info..although to be honest noone could blame you if you decided to keep your info to yourself.

brilliant...good luck.

Thanks

I would say what's going on in the combustion chamber is 60% of the "picture" with regard to pressure. There will also be pressure sensors in the exhaust ports and intake ports to aid in design refinement of the header, and more importantly, the valve timing.

The scale of this nitrous system is pretty far outside of the norm, so it's going to need a lot of help in the form of data to guide it's progress. Once the fundamentals are figured out, it get's a lot easier to scale everything upwards. So while there IS a target for the project, it's the building blocks, the tiny details, that are the focus of development right now.

I guess I can probably disclose the monster fuel system:

A1000 fuel pump
-10 AN Lines from fuel cell to pump, to regulator
#13301 regulator
-8 AN line to distribution block

I figured 700 lb/hr should work fine.

Decided to build a test bench that everyone could relate to.

The original idea was to use the new engine ECU that can log at 1000hz for data logging, but I realized that not everyone has their hands on a copy of Pi Toolbox. (More than the price of most nitrous systems) This would make it really difficult to share detailed data with people, so I decided to go with something a little more user friendly to the general public.

How about free software that you can view my data with?

I've got an Innovate Motorsports data logger on the way, which everyone can view test results with using Logworks3 software. (Free download from their website) The main downside here is that the sample rate is only 12.2hz, but it will be fine for showing pressure traces and duty cycle. Probably the main thing it will prove is the start and stop times for flow testing as well as the pulse rates used.

Fuel sytem:



Misc bits for this system and another one I'm working on:




Flow testing a custom 3 way distribution block from WON (Not for my system):

Spot the safety measure:

I reckon its just double connections per earth and signal to each pulsoid. Saves the chance of getting dirty contacts in your plug, mind you, on Deutsch plugs - that is almost impossible!

Sam

**EDIT** Looking a bit closer now, I can see the electrical component under the shink wrap too... Curious!!!

The 2nd set of contacts form a circuit to check that all the Pulsoids are connected. If 1 Pulsoid is not connected, the system can't be armed.

Basically, it's a series circuit going through every component connector in the system.

Yes, the Deutch Autosport connectors are very very nice to work with, the only down side is the tools required to assemble them cost a fortune. Worth it though.

I should have guessed that based on your past unfortunate experience, wise move I'd say.

Adam, it has been awhile, any updates on this ?

Maybe a few Pictures.




Rob

How's this for progress:



That's what I'm working on.

ahhhhhhhhhhhhhhhhhhhhhhhhhhhhh

Cute.
That reminds me, I'm about to visit my 6 month old Grandson for the first time in October.