Tuning the nitrous/methanol system.

One of the extreme beauties of burning methanol is its wide lean to rich burn limit range. The range can encompass a 15 to 20 percent change in fueling. And, for most of that range, there is only a slight difference in power. Methanol is a very impressive racing fuel. But,... if you push too close to the lean limit, and that's where some very addictive power is, it will burn you big time. So the trick is to stay 3 to 5% rich of this lean limit.
Now for our n2o/meth drag turbo anti lag system. Where do we set the mixture of the nitrous system? First off, the main fueling table should be set to a good power mixture off the nitrous. So get the main fuel map dialed in off the nitrous first.

 

Before we go on, let's discuss what a good turbo cam is. Track only engine.
What's a good turbo cam?
What's a good turbo/methanol cam?
What's a good nitrous cam?
What about a turbo, nitrous cam?
What about a turbo, nitrous/methanol cam?

How does camshaft egr play into it?
What is camshaft egr?

What are your thoughts?

 

Interesting read. New knowledge is almost always found off the beaten path. Nice work!

 

Have you tried a quick spool valve? Noticed a video in your youtube account...

 

He's planning to use both.

 

Thanks Torqued.

This is the Advanced Tech section of the TurboForums website, isn't it?
I thought I'd see a lot more grey matter being exercised here. Common guys. There are no wrong comments or answers in this thread. Let's all help each other learn something here.

Let me lay down some parameters for a cam choice and let's see what we come up with. We'll use my engine for this example.
224 cid V6. 3.937" x 3.06".
Stage I heads. Not the famed Stage II heads. Stage I is based on production style heads.
Intake valve size: 1.835". Exhaust: 1.500".
Fuel: Methanol.
Static compression ratio: 9.25:1
Nitrous is part of the plan to spool the turbo picked for this project.
Intake and exhaust manifolding will be tuned lengths.
The plan is to achieve crossover in the chamber. Cam specs should be designed accordingly.
A large turbo will be picked that will concentrate on two things. Putting the engine airflow at WOT smack dab in the middle of the efficiency islands, and a large enough turbine side to achieve combustion chamber crossover. Spool up time will take a far back seat in this choice.
Engine redline will be 7800-8100 rpm. Shift point will be 7200-7400 rpm. These limits picked to provide a somewhat reliable valvetrain with a reasonable lifespan.
The flow potential of the production style heads put the maximum obtainable hp level at around 1200 hp.

Other parameters:
3 speed Turbo 400 transmission.
N/C 10" TC with an off nitrous, 0 boost stall of 2400-2700 rpm.
4.10 rear gears in a 12 bolt housing.
29.5x10.5-15W tires.

What do you think about this combination? Pretty wild huh. There are so many things wrong about this combo. Yet.

So what should the cam specs be?

Oh! The intake is short runner, large plenum, 100mm throttle body. And the exhaust is stepped, long tubed tuned primaries, 1.625 stepped to 1.750 for a total 29", with merge collectors, short 2.125" dia. collector lengths dumping into a split 1.15 T6 turbine housing. The turbo is a FI91X or Airwerks S510/91mm.
More specs that just make this combination too wild to actually work.

edit: Car weight: 3200 lbs.

 

The next test and tune session will involve the quick spool valve. The video of the discovery of the n2o/meth dt als did NOT involve the quick spool valve.

 

A little background on my car, with plenty of pictures and explanations.

The intake manifold and nitrous injection system.
http://www.turbobuick.com/forums/fabrication-no-solicitation/275644-intake-manifolds.html

The exhaust system.
http://www.turbobuick.com/forums/fa...77078-custom-tuned-turbo-exhaust-systems.html

The quick spool valve.
http://www.turbobuick.com/forums/fa...-turbine-housing-flapper-valve-need-help.html

 

Alright, I guess I will chime in and post what I know. Or what I think I know anyways.

Good turbo cam = High lift, low valve overlap. Not to much duration.
Good N20 cam I THINK would be along the same lines of a good NA cam. Long duration, with good overlap for scavenging? But why would you need scavenging if you can inject N2O into the cylinder?... Hmmm
I don't know about an N2O AND turbo cam. I was under the impression you got a good turbo cam and just used it with N2O. Not so I guess.
Is camshaft EGR where the intake valve opens before the piston is at TDC on the exhaust stroke, but around idle you get reversion or backwards flow into the intake ports?
As far as turbo and meth... I don't know. If to much meth can quench the combustion process, I would think you would want a cam that can create some heat in the combustion process. Since a high overlap cam causes exhaust gas reversion at low RPM, it creates a lean condition. That is the only thing I can come up with to heat up the mixture. Again though, that is only around idle...

So for your engine, I would think you would want a solid lifter profile for faster ramp up's (if available), high lift, medium duration cam with less overlap than an NA cam, but more than your typical turbo cam. As far as actual measurements, I don't know for sure.

Ok, I gave it a shot. How about some insite now?

 

Very good. You did touch a little about using camshaft egr to heat the incoming charge. With the right manifolding and camshaft specs, camshaft egr does occur at rpm levels above idle, by the way.

 

So, camshaft egr can be used to help heat the incoming charge to better prepare the ultra cool mix for combustion. But, what if the amount of available egr heat was only enough to make a small difference. What could we do to increase the affect? Of course, we're only going to get so much help from camshaft egr, but what could be done to maximize the affect?

 

Using an old school exhaust heated manifold would get that pretty heated up. Or use an air/water intercooler that pumps engine water through it in the way a heater core does.

 

That would probably work, but would be beneficial ONLY when using the anti lag. Any other time, you are just introducing unwanted heated air.

Obviously the MORE boost you are building while using the anti lag, the more heat the turbo is putting out. That would heat the air, but I don't think that is the answer you are looking for. Most race intake manifolds no longer have water passages in them. This is to try to keep them cool. maybe revert back to a water heated intake manifold. That goes along the same lines as SprayedDime brought up though, thus introducing permanent unwanted heat.

Maybe you lean out the mixture to create more heat? That goes against adding fuel for the anti lag though.

Obviously you need to retard the timing enough for the anti lag to work, so adding timing to heat up the mixture wont work.

I bet once the answer is posted, it's going to be a face palm moment.

 

Why can't you use 2 coolers? Activate the water pump to circulate the engine water during burnout/staging to get the air charge warm. Have it on some kind of switch where it turns off when you release the t'brake and it starts the pump to circulate the ice water if you decide to use that.


Or just turn the pump off altogether. I don't think it'd take too long to cool back off with the flow/velocity of air we're talking about. Also if you injected the meth/nitrous mixture pre cooler it would also atomize better initially before it gets good and spooled up and starts making its own heat. That setup sounds simpler since the idea of using meth/nitrous is to keep the fuel system simple.

So, pump hot water thru an 'intercooler' to keep the intake charge warm then the pump shuts off at launch allowing the nitrous/meth mix to cool it while at the same time warming the nitrous/meth mix to be better atomized.

 

In real world applications it would not take the aluminum long at all to cool down. But we are talking about hitting the two step, building boost, then immediately starting the race with no time in between. It may only take the aluminum a full 10 seconds to cool back down, or even only 5 seconds if were lucky. By then your race is already half over.

 

Eh, depends on a lot of numbers I can't calculate. Nitrous expansion is pretty darn cold, coupled with the meth's ability to soak up heat, no idea how long it'd take.

 

SatanZ31 was getting close.
This is far simpler than adding more hardware or dealing with the mixture before it enters the cylinder.
Remember, we already have camshaft egr going on. How can we modify the temperature of the available camshaft egr?

How can we raise exhaust temp?

 

Study that video that I posted. In the second in-car scene, you'll notice at the tail end of the stall test that the rpm takes a sharp climb just before I get off the throttle. What is causing that? It's not boost. You can see that the boost gauge just tickles off the peg during the test.
The stall of my TC is very low, and the turbo is very large for my engine. So it's no wonder that the boost gauge doesn't wildly climb during the test. But what is causing that sharp rpm climb?

 

Retarding timing?

 

A few more clues.

When I do testing in the garage, I arrange a box near the exhaust pipe to pickup fumes and take them outside. During a stall test with the nitrous, whenever I do get that sharp rpm climb, the fume pickup box gets blown across the floor.

When I study a datalog of a stall test using the nitrous, the mixture at WOT stall, before the nitrous turns on, is 11.7:1. My wideband is calibrated to read out gasoline numbers. I've gotten used to using those numbers in my tuning. Just remember I'm burning methanol. When the nitrous activates I'll get a small lean spike to 12.5:1 and then immediately it will drop to 10.12:1. That's expected since my main fuel table is tuned for a safe power mixture and the nitrous/meth system is calibrated very rich. How rich it is, I'll explain later. Anyway, the moment the a/f meter goes to 10.12:1, which is the richest reading my meter will read out, the mixture reading suddenly skyrockets to 14.64:1 and maintains that line until the end of the test.