Why isn't there one? :confused: Here are my (dumb newbie) questions:

1) What's the basic purpose of a methanol system on a diesel engine, and how is it added? What options are there for the installation (injector location, mixture, pressure...), and what are the ironclad rules? What are the drawbacks & limitations (added weight, track-only, reduced engine life, higher maintenance...)? What are the prerequisites (turbo, intercooler, gauges, drivetrain upgrades...)? Same for the other 2.

2) Who needs propane? Who needs methanol? Who needs nitrous? Who SHOULDN'T use each/any? Assuming the engine is in decent overall condition (well-maintained or a reman), are there any engines/years/options/transmissions that simply can't tolerate these systems? Are they more/less effective in a particular climate or altitude?

3) At what point in my diesel ownership/use should I start looking at adding something? Is it best to add one system before the other? Does having one system preclude adding another? Does it help with MPG or passing power? Is one system better than another (not brand-names, but N2O vs. Meth vs. Propane)?

If there's already a FAQ like this, why isn't it a sticky? DevilsOwn has a thread running (http://www.dieselplace.com/forum/showthread.php?t=373303) about WMI, but I'd rather read one with participation from several vendors, staffers, & longtime members so the answers aren't skewed to a particular system or brand.

Thanks for educating a lifelong gasser! ;)

Well thats a lot of questions. I will take on a few.

Meth/water injection is sprayed into the air stream normally after the turbo and intercooler. In a diesel engine it can significantly drop EGT's. It also helps create more down force on the piston as vapors expand during combustion resulting in a slight increase in power. The system uses a electric pump some where in the range of 100-250 psi to inject the fluid as a mist which turns to vapor by the time it hits the combustion chamber.

Nitrous on a 6.2 or 6.5 is just about use less unless you are running something crazy IMOP.

On a duramax its a hole different story but only for guys running bigger numbers. I say that because its way too easy to make close to 500 horses with the duramax. Add a few bolt ons and a big tune and you are there. I would say the time for nitrous is when your going for big power (pulling, dyno, drag) and you dont have enough turbo(s) to keep up with the fuel demands with out some help.

Nitrous is also injected normally after the turbo and most of the time after the intercooler. It uses much higher pressures then meth/water and fires off at over 1000 psi. It is injected by nozzles and controlled by electronic valves that are called soleniods

There are different uses for meth/water injection. Some use it for power gains, others use it to control EGTs, and then others use it for MPG. A lot depends on the amount injected and the duration of the injection.

All three systems can be set to fire off at any one or multiple engine parameters. Engine speed, EGT's, PSI, engine temp, you name it. This means the systems can be engaged automatically when conditions are meet with little or no driver input.

Thanks for taking on a few.

So why is nitrous uselss on a 6.5? What about propane - what's the purpose, and who should use it?

Thanks for taking on a few.

So why is nitrous uselss on a 6.5? What about propane - what's the purpose, and who should use it?


Well, its not necessarily useless on a 6.5, if you have bigger injectors and the pumped cranked up or putting out more fuel than the turbo will clean up, then nitrous would give you the extra air to burn that un burnt fuel. However, im guessing a 6.5s lifespan would be very limited with this kind of operation. Propane on the other hand is more useful if your running out of fuel. Cant burn all the fuel you are throwing at it, nitrous is an oxygen extender and will create a more complete burn, Propane injection is more for a running out of fuel situation. At least thats the jist i got on propane from poking around reading on here.

The 6.5 is highly susceptible to detonation (pre ignition) with anything flamable injected into the intake, hence why it was (is) uncommon.

There was some propane kits for the 6.5 available for a while, but theres a reason you don't see them anymore.

As for a FAQ, if someone here would like to write a detailed one for this forum/topic, bring it to a staff members attention after posting it and it would be considered for a sticky. ;)

I say nitrous is useless on the 6.2/6.5 is due to there limited ability to handle larger power. You have a very high compression engine that you have now boosted that has been known to bend rods and brake crank shafts and you want to add more power. Plus i dont think the head gaskets are going to like it too much. You can push one of these motors to its dependable limit with a good turbo with no problem.

OK So the 6.5 (and 6.2???) is just too weak to handle any real power-adders, right? But meth isn't a significant power-adder, so it's OK?

You mentioned a "good" turbo; is the stock one somehow inferior? I realize on my truck that the wastegate is controlled by the PCM, and so it's built NOT to provide much boost pressure. But is that really a turbo fault, or just an effect of the total engine management strategy on a relatively weak engine?

For a 6.5 around 9-11 psi seams to be the sweet spot between boost and durability. When you start going much higher then that you can start having problems with out dropping your compression to compensate. Keep in mind the 6.5 is something like 20 to 1 CR which is very high for any turbo diesel. The GM turbo's are decent turbo's depending on which model you have. There are 8 versions of the GM-X turbo. Some versions of this turbo depending on the number flow slightly better then other versions. I cant remember exactly but i think GM-4 and GM-8 where two of the better turbos but cant remember why. One of the Detroit guru's might drop in to correct me.

My mechanical pump 6.5 was running about 3-4 pounds of boost after intake 3 inch down pipe with 4 inch strait pipe. I was getting a little black smoke when i really got on it. So one friday me and friend pulled the waste gate off and made a manual controller (took less then 2 hours to take off and build) I did a build thread on this in the 6.5 section and it might be under the DIY section now so i will leave the details about the build out. But the result was noticed instantly. At first we had it turned way down just to be on the safe side but after a few test drives we set her about just at 10lbs. No more smoke, boost comes in a lot faster, and the truck was way more responsive. After a few weeks i ended up turning it too spike at 13psi and holding around 11. It was a good combo for me and the truck seemed to perform well doing this.

OK So the 6.5 (and 6.2???) is just too weak to handle any real power-adders, right? But meth isn't a significant power-adder, so it's OK?

You mentioned a "good" turbo; is the stock one somehow inferior? I realize on my truck that the wastegate is controlled by the PCM, and so it's built NOT to provide much boost pressure. But is that really a turbo fault, or just an effect of the total engine management strategy on a relatively weak engine?

Water/Meth injection can be done on the 6.2/6.5 and can help control IAT's and EGT's once you start turning of the boost and fuel. However i would use a very small nozzle and use it for more of a safety net when towing. Just my 2cents.

Meth *IS* (a very significant) power adder on any engine.

Water meth mix, less so, but on the 6.5 you need to be very careful on the mix ratios otherwise you will detonate. Detonation on the 6.5 is a bad, bad thing.

^^^^
Very well said and right on the money.

OK So what I'm gathering is: water isn't a significant power-adder; it's mainly used to reduce IAT (like an intercooler) and EGT (when other power mods have been done). Right?

I'm not necessarily looking to modify my truck, and I don't particularly need more power. My truck is 14 years old and hasn't had any major problems, so reliability is VASTLY more important to me than winning races against Vettes. I'm just trying to get a grasp on what these systems actually do, why someone might need them, and how they interact with each other.

Thanks for all the info so far.

Meth/Water injection is great for MPG and to reduce carbon. It is probably the safest of the three for a 6.5.

Mark is doing a long-term test of WMI in his 6.5 for MPG, and from what he's posted so far (in the 6.5 forum), he's barely breaking even doing long hauls and driving conservatively. So for the typical daily-driver, it doesn't seem to pay off for MPG.

Interesting. I still see added benefits. When you think of the MPG and cost factor it doesn't make sense. I mean the average kit is going to cost about 500 bucks. That is easily 120 gallons of diesel fuel. Giving that the gains from meth/water normally only give you .5 to 1 MPG increase it would take a long time for it to pay for its self like that. I would think the longer turn benefits would be the reduced EGT's and a cleaner intake track.

So it's sounding like WMI is more of a maintenance thing than performance or MPG, at least on the 6.5L. To me, that's a good reason to add it, but it'll have to wait until I have a pyro with at least one programmable output. I'm not going to install a 40gal tank & run it continuously.

So you are going to set your pyro to fire off your meth once a certain EGT is reached.