Advancement of fuel delivery?

[Pablo]

Don

Since Methanol has about 10% more specific energy than Gasoline, I would say that your 190 shot is more like a 209 hp shot.

[DonWG]

Originally Posted by Pablo

Don

Since Methanol has about 10% more specific energy than Gasoline, I would say that your 190 shot is more like a 209 hp shot.

That is what you would think. But when you take into consideration the extremely cool mixture of alcohol and nitrous together, it makes you wonder if the mixture is too cool for the most efficient burn.

The 1/2 rated theory is referenced from a book I read. The name of the book is:

Nitrous Oxide Injection by David Vizard. Published by S-A Design.

I might add that the book also made it clear that not a lot of information about the use of nitrous and alcohol was available.

[DonWG]

With the system setup the way it is now, I have a few options on how or I should say when to activate the system to give the best launch. I have not explored them all, but I'll list them for you.

Since the nitrous system is basically controlled by the WOT switch, it's a matter of choosing when, during the countdown of the tree (three amber tree), to activate the nitrous.

The slowest and safest launch is to go WOT on the last amber or basically at the same time the transbrake is released. You could wire in a relay to control this activation with the transbrake button to get good consistency during launch. If you have a lot of volume in your nitrous system, you'll end up with a soft hit launch until the liquid nitrous begins to flow in ernest from the nozzle.

You can increase the intensity of the launch by going WOT at anytime before the release of the transbrake. The last few runs at the WCN this year, I went WOT on the second amber. It was a very controllable launch. I tested going WOT on the first amber only once. I would not do it again without attaching the wheelie bars to the car. It was amazing. If you've ever seen Scott's truck leave the line, it's kind of like that. Something I'll eventually work myself up to, I'm sure.

Another option involves using another delay box. Go WOT on the first amber and have a delay of your choice programmed into the delay box. Sounds neat, don't it?

Then there's the option of using a controller that would be capable to turn on the nitrous for spooling, turn off during peak cylinder pressures and then turn back on during the last part of the run, past peak torque rpm.

[DonWG]

Another variable that can be used to control the intensity of the nitrous hit, particularly if your using a large hit, is to play with the amount of nitrous retard. With retard more than optimum, the hit softens.

Ain't this cool?

The amazing thing is, I'm not the least bit in a hurry to study my datalogs of the last event. Normally, I would be all over them seeing what my spool up was like, what my converter stall looked like, what my rpm drops looked like at shifts, etc. Nitrous is amazing.

I've mentioned this a few times and I'll mention it again.

Nitrous with turbocharging is the perfect marriage.

Nitrous provides immediate torque on the bottom end that trails off with rpm, while the turbocharger, when sized correctly, can be used to take over on the top end with the nitrous helping to get the big tank spooling on the low end. Imagine something that increases low end HP while it helps to spool your large turbo and allows you to avoid the typical distracting launch procedure that is so common these days. Now you can concentrate on cutting a good light.

[DonWG]

I've posted a compilation of all the runs made this last Sunday on You Tube.

DRW at WCN @ Speedworld 2007

Notice how the car leaves like a n/a car.

[DonWG]

The next discussion will be on a much more simple system. A single nozzle system. This would be the kind of system that would be very easy to hide. There are plenty of ways to disguise a line and nozzle and with the amount of plumbing before and after the turbo, there are plenty of choices for discreet placement. I wouldn't be surprised if there weren't a few secret systems already being used in some 'class' racing. Nitrous has been known throughout racing history as the favorite tool of choice, located in the cheat drawer of your favorite crew chief's tool box. In fact, if I were to involve myself in class racing, with what I know now, I would be very tempted to use my fabricating skills to come up with a stealth nitrous system. Why not? What are they going to do? Take away my name? Heck. Just a one second shot could make the difference of whether a record is made or not.

The first question about nozzle placement is where. Before the turbo. After the turbo. Before the intercooler. After the intercooler. Before the throttle body.

The next question should be wet or dry. Also, where you place the nozzle would have a lot to do with whether you go with a wet system or dry system.

Next question. How should the nozzle face? Should it spray upstream or downstream. Will where you decide to place the nozzle have any bearing on the direction it sprays?

To search for the answer to some or all of these questions try visiting the Wizards of Nos site/forum. There is some very interesting information there.

[DonWG]

Now the question that I'm dying to know the answer to.

Let's take a compressor that is operating at a pressure ratio of 2 to one. The air entering the turbo has the normal content of oxygen that is in the air all around us. The oxygen content is twice as much per cylinder volume after the compressor. Keeping the math simple and not taking into consideration the temperature rise. Is this correct? If so, then if we start with an air mix that has a higher percentage of oxygen in it and run it through the compressor, have we still doubled the oxygen content per cylinder volume? Keeping heat out of the equation for now. I am in desperate need of some math wizards on this one.

[Pablo]

Originally Posted by DonWG

Now the question that I'm dying to know the answer to.

Let's take a compressor that is operating at a pressure ratio of 2 to one. The air entering the turbo has the normal content of oxygen that is in the air all around us. The oxygen content is twice as much per cylinder volume after the compressor. Keeping the math simple and not taking into consideration the temperature rise. Is this correct? If so, then if we start with an air mix that has a higher percentage of oxygen in it and run it through the compressor, have we still doubled the oxygen content per cylinder volume? Keeping heat out of the equation for now. I am in desperate need of some math wizards on this one.

I may be in over my head on this one but I think if you are starting off with a infinite amount of that air with more oxygen in it then you would certainly be doubling its density after the compressor regardless.

But, if I am to guess where you are going with this, if you inject nitrous pre turbo then the amount of oxygen vs volume is going to increase. As engine rpm increases, so does volume of "air" processed but since the volume of nitrous is a constant your're going to have an ever changing oxygen content vs volume of "air" pre turbo and therefore post turbo. The nitrous volume would have to have some sort of ramp to accurately predict the amount of oxygen actually entering the engine to keep it constant.

[DonWG]

Originally Posted by Pablo

I may be in over my head on this one but I think if you are starting off with a infinite amount of that air with more oxygen in it then you would certainly be doubling its density after the compressor regardless.

But, if I am to guess where you are going with this, if you inject nitrous pre turbo then the amount of oxygen vs volume is going to increase. As engine rpm increases, so does volume of "air" processed but since the volume of nitrous is a constant your're going to have an ever changing oxygen content vs volume of "air" pre turbo and therefore post turbo. The nitrous volume would have to have some sort of ramp to accurately predict the amount of oxygen actually entering the engine to keep it constant.

Very good point.

Another point. With the cooling affect of the nitrous, you have also increased the density of the normal air entering the turbo, further increasing the oxygen content per volume. This is starting to take temperature into consideration.

Another point. If you start out with a lower temperature pre-turbo, you'll end up with a lower compressed temperature after turbo and the intercooler capacity can be lessened if mounting space is a problem.

[DonWG]

I would imagine it would be best to inject far enough before the turbo to give it time to change state before coming to the compressor wheel. I could be wrong.

Would injecting just after the compressor cause a pressure drop that could somehow help compressor efficiency?

What about injecting directly into the scroll. Directing the spray to help spool the turbo. Much like blowing on a pin wheel.

[DonWG]

What I'm thinking about for my own project is injecting a small amount of nitrous around the turbo compressor area. Position still to be determined. Maybe trying different positions, since it's only a matter of setting up 1/8 npt bosses. Still using the large system to spool the turbo via exhaust mass flow, but having the small system continually inject throughout the pass to give me just that little edge. Mainly, just enough to break into the 8s with a T76. Just like what Scott has done.

I'm talking about starting with a tiny 25 shot maybe, harmless really, and seeing what I get.

Small steps. Small steps.

[TurboTR]

It can work, but the small problem there is the compressor blades are not angled correctly for that (unlike the turbine side). We shot compressed air like that for spoolup assist on a turbo diesel truck efficiency enhancements project.

Be sure to have adequate timing retard (and fuel to match) for your small shots and there's no reason to be worried. You'll hardly even sense a 25 shot- it's tiny compared to your current power level. A 50 shot will just whet your appetite for more Plan to put a 100+ shot on it

TurboTR

Originally Posted by DonWG

What about injecting directly into the scroll. Directing the spray to help spool the turbo. Much like blowing on a pin wheel.

[DonWG]

Thanks TurboTR. Your advice is reassuring. I see your point on the blade angle. I'm thinking that I'll inject the way Scott has. The shot size will only need to be enough to click off an 8.xx. That will satisfy me. If I don't feel it, that's fine. After the 8 is under my belt, I'll probably turn the knobs down and let the engine live a long life.

On another point. I noticed your sig. From your experience, have you been able to come up with a general max cylinder pressure limit with our engines?

Is this the same fellow from long ago that started tuning services using cylinder pressure measurements? King?

[TurboTR]

How much do you plan to retard the timing for your nitrous?

You probably remember me correctly; in fact you built a max effort 200R4 for me around the mid/late 90's. I worked at an engine research institute for several years around then as well.

Personally I'm comfy with about 1600 psi peak on my own engine. I don't know how much more it could take safely, but when I hold it ~ to that it shows no gasket damage, etc. It's probably on the very conservative side. But in general most engines would probably do well to stay below 2000 psi peak. Even for heavy duty diesel hardware- ours is not as strong.

Don't confuse what you get from BMEP calcs with real cylinder pressure (as we've mentioned before).

The good news is, a statement like "Nitrous works by drastically increasing cyclinder pressure...", which you see in any popular rag, etc is... dead wrong in fact. At least when done correctly- it can of course drastically increase the cyclinder pressure, but then you need to make sure to include a good quality engine parts broom in your tow rig too. That statement (and equivalent) is generally accepted because it seems to make intuitive sense at first, but the reality is that the engine simply cannot keep a lid on and withstand drastically increased cyclinder pressure (along with the drastically increased forces on everything). The real mechanism for increased power is not as obvious, but fortunately for all of us who love drastically increased power it's not via "drastically increased cylinder pressure".

TurboTR

[DonWG]

Ahh. It is you. You even remembered that discussion we had. Hope everything is going well with you.

The amount of retard I'm presently using is 8 degrees. I have used as little as 4 degrees, but the circumstances that I used it in scared me a little so I added 4 more for a total of 8 until I was sure the fuel map was squared away. Actually, that is still an area that I can play with if I feel I need a quicker launch. As long as traction doesn't become a problem. The one time I tested it with just a 4 degree retard, traction wasn't a problem, but the fact the wheelie bars weren't on the car that time was. I was definitely caught off guard. The throttle pedal kinda jumped off my foot, if you know what I mean.

I just finished studying the latest datalogs and the nitrous is on for a total of .425 seconds from going WOT, to spooling the turbo to 16 psi @ 4,655 rpm. At .646 seconds from going WOT, the boost has reached 283.8 kPa @ 5,632 rpm.

[DonWG]

Todd. I'd appreciate it if you could enlighten us a little more on your last statement about the circumstance in which nitrous gives us dependable, safe power.

[Chevota]

Originally Posted by DonWG

Thanks TurboTR. Your advice is reassuring. I see your point on the blade angle. I'm thinking that I'll inject the way Scott has. The shot size will only need to be enough to click off an 8.xx. That will satisfy me. If I don't feel it, that's fine. After the 8 is under my belt, I'll probably turn the knobs down and let the engine live a long life.

On another point. I noticed your sig. From your experience, have you been able to come up with a general max cylinder pressure limit with our engines?

Is this the same fellow from long ago that started tuning services using cylinder pressure measurements? King?

Can't wait for that video Don Don't care to much about what the time board says as much as studying the launch and 60ft mannerisms. Fortunately the majority of my runs are un-eventful as opposed to yours. Watching your runs that you posted on You Tube confirms just how tight you convertor is! I also think it might be negatively affecting your et's to a certain extent downtrack. I have several thoughts regarding your "new setup" as well as some new ideas you might want to look into. Not much of a typist so I'll be giving you a call tomorrow instead of posting if that's ok?

scott wile