can NOS or water/meth exceed turbo HP limit?

from FAQ just to show yes i'm trying to read: "12. Nitrous Oxide

Not normally suitable for a diesel engine. Since diesel engines normally run lean (except when belching black smoke!) adding more oxidizer isn't going to accomplish anything. If the engine is over-fueled due to extensive other modifications, then this might help power output ... for a little while, until something breaks."


Assuming i'm building a strong enough engine (like a BHW/ALH hybrid with upgraded rods and pistons and such)

And assuming I only want temporary power over the 'normal limit', like maybe I have a turbo limited to 150hp, and i'd like 180hp but not so often it justifies the further upgrade cost.


Would nitrous help me do this on a diesel to avoid the turbo running out of breath? In theory i'd assume yes just wondering if there's any challenges to this...

What about the water/methanol injection? This would cool the EGT for sure, but without extra air and oxygen I don't know if that does much good, or only a tiny bit of good. I know diesels need enough air to support the fuel, but i've also read of cases where a different fuel (like CNG) can help the primary diesel fuel burn better and more completely, though I dont know if that happens with methanol, or whether it's a miniscule (like 5hp) or nontrivial difference. (like 30hp)

Nitrous adds more oxygen and water/meth is a added source of cooling and fuel. A small shot of nitrous would clean the exhaust up and add more power if you have excess fuel to burn. However personally a much better option would be to go with a used take off of a new tdi from someone who has upgraded. Most if not all of those can support the 180hp you mentioned.



But a lot of your threads seem to be asking about towing and max reliable hp. If that's the case I wouldn't be looking at nitrous. Go with a mid sized turbo so you have acceptable spool and a conservative tune with lean afr's. Max sustained hp not peak hp is whats important with towing. No point in having that 180hp with nitrous for a few seconds if the turbo can only stay cool under 130hp sustained. Far better to have a larger turbo conservative tune and only 170hp but be able to hold that for as long as needed.

I absolutely agree! Nitrous is not the choice for pushing these engines.

On the other hand, if you're interested in improved fuel efficiency and power through propane injection

Sent from my Armor_2 using Tapatalk

I'd go with water/methanol over nitrous. Water/meth will add some oxygen as well as fuel while keeping intake temps down at high boost levels.

Sorry, had to too run and didn't get a chance to finish my statement on propane injection.
Propane has successfully been used in diesel engines and can improve fuel efficiency by helping to combust the diesel. It is run in forklifts indoors and can be modified to other applications.
I've considered it myself and the greatest difficulty is injecting at the correct volumes for the situation and needs.
A crude model can be created and injected in the intake manifold and pushed through with boost. This requires a DOT pressurized tank that will exceed the boost pressure, backflow regulation, an electric shut off valve and flow regulation (best is variable, fixed is easier).
I was considering a fixed rate for cruising speed and an electric valve with cancelling switch in the cockpit (goes off with relay, status off until pushed again) and connect to the 109 relay for the circuit.
This method is much easier than variable as there would be need for a sensor, MAF signal used possibly, to electronically control the input; or a mechanically controlled regulator that would have to be adjusted by the driver. Could create an extension for mechanics, or used an electronic control from the cockpit.

This is a completely theoretical project that I have been contemplating for quite some time now and I haven't made it past understanding the components necessary as it's a fairly costly and involved project.
Aquisition and placement of a DOT approved high enough pressure propane cylinder is difficult enough, let alone the plumbing and regulation. Once successfull it'd be remarkable. Improved HP and economy would be gained by more complete combustion of the primary fuel.

Sent from my Armor_2 using Tapatalk

I wouldn't bother with propane injection. That's more for the 1000HP truck crowd.
But, fortunately for the propane curious, the vapor pressure of liquid propane (LPG) is
already around 100 psi depending on temperature. That's almost 7 bar. Should do.

turbobrick240 said:

Water/meth will add some oxygen

Click to expand...

No, it will not do that. Injected methanol will make AFR richer as it needs oxygen to burn.

p0wer said:

No, it will not do that. Injected methanol will make AFR richer as it needs oxygen to burn.

Click to expand...

Water/meth mostly adds O2 by creating a cooler, denser air charge. The denser the charge, the more O2 it contains. There's also some O2 liberated from the water and methanol molecules themselves.

turbobrick240 said:

Water/meth mostly adds O2 by creating a cooler, denser air charge. The denser the charge, the more O2 it contains. There's also some O2 liberated from the water and methanol molecules themselves.

Click to expand...

If the turbo has already hit choke then lowering the density would just lower the boost required to move the same mass of air. No extra oxygen is added by the water injection.

Exenos said:

If the turbo has already hit choke then lowering the density would just lower the boost required to move the same mass of air. No extra oxygen is added by the water injection.

Click to expand...

As long as the water/meth blend is lowering intake temps, it is adding O2. How much it adds depends on how much it's reducing the intake temp, how much boost is run, and the ratio of water to methanol. Something around 50/50 is usually ideal. Straight methanol would add O2, but also adds fuel, so the air/fuel ratio might be richer despite the added O2.

turbobrick240 said:

Water/meth mostly adds O2 by creating a cooler, denser air charge. The denser the charge, the more O2 it contains. There's also some O2 liberated from the water and methanol molecules themselves.

Click to expand...

itty bitty turbo is choked on turbine side

no matter what you do to the intake air, that is going to continue to be the case

OP just wants a bandaid fix to parts he hasn't chosen yet where there isn't really one that isn't hack as all heck, like cutting off the exducer of the turbine

[486] said:

OP just wants a bandaid fix to parts he hasn't chosen yet where there isn't really one that isn't hack as all heck, like cutting off the exducer of the turbine

Click to expand...

Yeah, a bigger turbo, intercooler and injectors would be more effective for sure. Still, emergency war power has its place.

[486] said:

itty bitty turbo is choked on turbine side

no matter what you do to the intake air, that is going to continue to be the case

OP just wants a bandaid fix to parts he hasn't chosen yet where there isn't really one that isn't hack as all heck, like cutting off the exducer of the turbine

Click to expand...

OP simply asked questions to educate himself from the looks of it. It doesn't look like he necessarily is looking to hack things up if you go back to reread his single post. Everything else has been other people responding.

ToxicDoc said:

his single post.

Click to expand...

I'm talking about the other few threads he's made on his plans

turbobrick240 said:

Yeah, a bigger turbo, intercooler and injectors would be more effective for sure. Still, emergency war power has its place.

Click to expand...

eh, why bother with that when you can have the power all the time without filling a bottle or separate res?
I used to think about putting a valve in the car's dash to shut off the wastegates, but then I realized that would do nothing but bad things.
I can just set it up to make all the power it'll make and just short shift it when I don't want all the power.

[486] said:

I'm talking about the other few threads he's made on his plans

Click to expand...

I didn't see those. thanks

[486] said:

I can just set it up to make all the power it'll make and just short shift it when I don't want all the power.

Click to expand...

This is definitely the one real option, setting it up so it makes the power you want.

My only thought to propane was efficiency and the cost benefit hasn't been great enough to justify it.

Sent from my Armor_2 using Tapatalk

And now that you have me thinking about this again I have found some interesting information. One review by someone using a Power Shot system, on their website of course, said 10% increase in diesel to a 2.5 gallon tank over 3500 mi...
Which is approximately .0021¢ per mile at those rates of consumption.
This actually made a thought I had the other day, to use the small grill size bottles, more plausible. I could easily mount one of those above the transmission and mechanical regulation is much cheaper.

Stop making me revisit such ideas, it makes me more likely to do it...

Sent from my Armor_2 using Tapatalk

Really just need a solenoid valve, propane regulator, and mounted bottle.
The bottle listed below is small and I am not positive how viable a single would be. Considering 2 with a manifold as best practice possibly. Plumbing this into the regulator, (and possibly a flow regulator to maintain pressure and flow rate) then through the 12VDC solenoid actuated by a relay that either needs to be switched on by boost sensor, or IP voltage.
This is what really needs to be figured out for implementation, or buy the power shot.


12 VDC Solenoid valve $20 - $40
https://www.amazon.com/HFS-Electric...ocphy=9010330&hvtargid=pla-351281160128&psc=1
https://ussolid.com/3-8-npt-electri...6tL8Ydd7UP-FdaPxkD6aQbs9y5-Kb1HoaAqZIEALw_wcB

Regulator $40
https://www.amazon.com/Adjustable-P...ocphy=9010330&hvtargid=pla-485240549026&psc=1

Propane bottle $15
https://www.homedepot.com/p/Flame-K...ZviWMVFm5gKM2Ge1mlCm5qkWTrdYZjUgaAjDbEALw_wcB

A truck forum will have the most info:
https://www.thedieselgarage.com/for...hot-2000-propane-injection.html#/topics/19653

Substituting propane for a percentage of the diesel fuel that would otherwise be
consumed is not the same thing as increasing the efficiency of diesel combustion.
The cost per BTU of using diesel vs. propane as a fuel is surprisingly close.
One fuel or the other may have a slight advantage depending on daily local pricing changes.
Once you add in the cost of the equipment needed to effectively use propane and
the added weight to carry it, any real advantage is probably rendered moot.

in a nut shell, NOS is great for diesels with a lot of smoke, usually thats from not a big enough turbo or just poor tune or just raw HP.
water injection is fantastic at lowering EGTs, so is NOS
thats about it, meth injection is done with water so your just adding EGT's back into the game with some extra power IF your not blowing black smoke.
most poor or makeshift builds who throw on water meth dont see much improvement other than EGT's as the smoke leves are indicating a lack of O2.

In the correct proportion of propane you are not substituting, but inputting a highly volitle gas into the cylinder and it's used to ignite the diesel more completely.

Absolutely a fact that substitution yields equal results. However ignition with about 1% propane can definitely render improved efficiency and thus power. That 1% must be calculated in for true cost benefit analysis.

The diesel crowd is definitely benefiting from both, some more than others. The optimum proportion is going to be a trial and error figuring and I can't find the digital systems mentioned in the truck forums. Would be nice to have a computer connection to refine the injection quantity of the propane. Might make it just tempting enough if the price was right.

ToxicDoc said:

OP simply asked questions to educate himself from the looks of it. It doesn't look like he necessarily is looking to hack things up if you go back to reread his single post. Everything else has been other people responding.

Click to expand...

Yeah I tend to research alot of angles before narrowing down removing the clear loser options while still mentally exploring things that might work. Time is cheaper than spending thousands building something I dont need I mean and i'm trying to learn from others mistakes so I don't have to make them myself?


There's too many posts to respond individually to all of them, but a few things on my mind catching up on the thread so far:

I've considered propane, actually more interested in CNG if I went that route (because it seems like a way to add fuel WITHOUT having to upsize the injectors, but cost per btu is also lower) but everything I was reading on the more heavily modified diesel forums seems to be mixed... what I remember reading in the past was they consistently, consistently, say water and methanol is the way to go because it's alot more predictable in higher percentages.

I've read a 5% CNG mix (or probably anything probably propane too, or probably methanol) apparently cleans up combustion and boosts efficiency, but as you turn it up more, increasing risk of detonation (octane is high but turbodiesels have real high pressure) and unpredictable burn patterns of the mixtures start causing more risks than benefits vs water-meth which is apparently more predictable. Heck I read of some guy squirting in normal gasoline as a power booster in diesels, I think it was more of an australian thing, and again apparently worked up to a point. It all sounded like if you want to overfuel to the black smoke level, do it with diesel, not added propane in short, and if you want to add a secondary fuel at all methanol is the safest to add. I read people have killed engines turning propane/CNG it up too far which doesn't sound fun and the fine edge is really hard to know where it is. Propane likely being a bigger risk than CNG due to lower effective octane (isn't something like propane 105 octane and CNG 130?) which sounds kind of like 'tipping the can' of nitro strategy of racing...


I remember reading propane on the older diesels used to be more of a thing because they werent running as close to the limits of cylinder pressure, apparently it wasn't a big deal to ghettoize something to a Ford 6.9 IDI or GM 6.2 back in the day. They had higher compression ratio pistons but nowhere near the boost diesels run/you couldn't run a converted gasoline engine with 35psi and 16:1 on propane i'm pretty sure of that so i'm less sure how it applies to modern engines. If I were to play with propane or CNG i'd also be concerned about if it might throw the computer out of whack somehow...

I'd read that water-methanol gives the extra fuel while cooling the charge and without the apparent random engine killing in stouter percentage. Even if I didn't use the methanol i'd definately want to do the water injection - i'm not sure why it's not a 'bigger' thing here on the VW board, it's huge on pickup diesels. Water-methanol is also conveniently available in jugs of blue power every winter where I am. It's not the perfect percentage for power, but convenience counts for alot. (then again, propane is also super common so it has that over CNG if it could actually work, i'm just concerned that it is not as safe for the engine as pure diesel or diesel plus methanol)


If you have contrary references though i'm all ears, and the above is just from memory/I might have something misremembered. Any added fuel though is going to need more oxygen and my original question is still valid... even if they think i'm wasting money could I just NOS a 150hp turbo up to 200hp of airflow assuming I have the fuel to make 200hp? Is there anything somehow more dangerous to the engine of doing it that way?


I like how turbobrick240 put it "emergency war power". Thats honestly a BIG part of whats making me think I need "xxx HP" in the first place. I already tow 1200lbs of trailer (total 4200lbs vehicle/trailer/load) with a 100hp Saturn and have no complaints at all - except that one time in cincinnati when even in the far right it felt like people were trying to drive right over me. There's literally only about 5-7 times I would have needed a squirt of 10 seconds of another 50hp or so to avoid scary situations, I would have happily paid $30 to refill a nitrous bottle or whatever for that, when it's that intermittent. As opposed to say spending another $2000 for performance upgrades beyond what may be more common.

It's like could I just choose performance accessories for an engine build for 150hp sustained power and use NOS to squirt it up to 180-210hp on occasion? Is it then a question of "pay as you go" 200hp on NOS vs 'saving money' of doing it on just fuel? Because my right foot is light enough i'm fine with that... is it two ways to achieve the same outcome?

@midnightoil
We're definitely in the same page in the end. I was looking up the digital propane injection and that would be much more appealing to me.
As you said in smaller percentages it's gold, however, when you start looking to boost power you get into trouble. Air is no issue when looking to boost economy as the turbo pushes plenty when tuned properly.

I also prefer the thought of methane, or another fuel to propane, however, propane is viable and available to this application. Being reasonable about the desires and expectations is necessary.

I have looked more into browns gas and even had a hydrogen generator on an old Tacoma is mine. I realized to do it properly and gain benefit I would have to separate the gasses and put the O2 through the intake and the MAF. The issue was the O2 sensors sense the extra O2 in the exhaust and compensate with fuel. If you vent most of the O2 and inject only the hydrogen sensors will sense the lack of O2 and decrease the fuel to compensate. I never got around to creating the pressurized separation container necessary to supplement hydrogen for gas and it sounds like a ludicrous idea on a diesel.

@eddieleephd well I will agree with that, propane is going to be easier and cheaper to convert (though twice the cost to refuel) vs CNG, just grab another clunky rusty BBQ container from the nearest gas station.

It's just that the cost per BTU of added power i'm assuming is going to be no better than with methanol... so in that case why not just go methanol, while also gaining the higher octane (vs propane) and charge cooling benefits? If anything confuses me on this board it's why there isn't more talk of water-meth injection I guess... it just seems to be all over every other diesel board i've ever posted on as a win-win-win tried and proven with little cost and downside, even in DIY fashion. The FAQ acts like it's almost experimental or a bit out there... but maybe it is for VW people even though it shouldn't be.

I bet you don't hear many guys talking about octane values on those other diesel forums . Cetane values are used in compression ignition engines. It's basically the opposite of octane.

turbobrick240 said:

I bet you don't hear many guys talking about octane values on those other diesel forums . Cetane values are used in compression ignition engines. It's basically the opposite of octane.

Click to expand...

Either way it's a measure of combustibility, just under different means.
Volitility is the beneficial aspect of propane and only in small quantities as a combustion improving additive. This is also true if hydrogen and methane. When you start supplementing fuel work another kind the equation for entropy still holds and the benefit begins to decline.
The benefit is greater in less efficient engines and still only if you're improving combustion not replacing/supplementing fuel.

Not to high jack this thread, but I thought once I heard that Propane injection was a good power added for Diesel, and it has a similar effect to injecting NO2, while being able to be ran constantly. I also heard it can reduce EGT, and get you a decent mpg boost even while towing.

Nitrous injection has fallen way off in the last decade or so. There was a proliferation of cheaper enthusiast products. Followed by a proliferation of cars with cheap installs needing a new engine. Propane injection has fallen way off as well.


Water methanol has many positive benefits, and it seems like that's where many of the "Fast and Furious" crowd has moved their sites to. (that being said, a highly tuned Methanol injection car is in nearly as much danger as a highly tuned up NOS system. Things go wrong, things go too lean, things go boom...)

johnnloki said:

Nitrous injection has fallen way off in the last decade or so.

Click to expand...

nononono this latest guy is saying nitrogen dioxide insquirtion