NITROUS OXIDE ( nos / n2o ) advice forum

Anyone point me towards technical info on how WI alcohol/water ratios affect a diesel, particularly when boosting power with nitrous?

I don't understand all the technicalities of the diesel combustion process and how differing A/F ratios affect the engine in terms of heat and damage etc.

Perhaps it would go a long way to explaining how a petrol engine can take up to 100% methanol while I've been advised not to go higher than 50% with a diesel, and even less (20-30%methanol) if using nitrous?

Their main argument is a rather vague - you'll destroy your engine because of increased pressures and EGT's.

The limitations of diesels has nothing to do with methanol and water really, nor can you use any petrol engine related info to guide you with what you can or can't do with a diesel.

A petrol engine can have the ignition timing relatively easily adjusted but although the timing can probably be adjusted on a diesel, few people (in comparison) would know how to do it, although now they are ECU controlled it should certainly be easier.

You'll also find that the problem is due to 99.9% of diesel experts, knowing NOTHING about enhancing the performance by any great extent, never mind to the limits. Likewise most water experts (of which I would risk stating there are few) and/or fuel experts know little about diesel engines but what is needed is someone who could be said to be an expert in all 3 subjects, diesels, fuels and water injection.

My knowledge on all 3 is growing but I wouldn't yet claim to be an expert in any of those 3, so I can't give you a definitive answer yet but based on what I do know, the problems are as follows;

1) Because a diesel ignition is achieved by timed injection of the fuel directly in to the combustion chamber, adding fuel through the inlet manifold, has the potential to screw up the ignition timing accuracy in the worst possible way, by effectively advancing it.

2) This problem can be overcome to some degree by adding a very high octane fuel that will resist self ignition when heated and compressed. Methanol and propane are 2 such fuels that fall in to this category.

3) Unfortunately there is a limit to what can be achieved using this method, because each increase pushes the engine closer to detonation because the timing is not being retarded (as would be the case if it were a petrol engine for example), and adding water is the simplest solution to raise the limit further.

4) If you injected methanol in place of or as well as diesel directly in combustion chamber and it was timed correctly, I'm quite sure you could run on 100% methanol.

5) The reasons you have read elsewhere for the causes of diesel engine failure are actually the results of detonation, which is a consequence of premature ignition.

6) All the references to what percentage water/methanol you can use on any application are almost certainly just as a consequence of the limitations that inadequate hardware causes and nothing to do with what an engine can handle.

7) Under the normal diesel fuel injection process, the A/F ratio is of little to no concern (from a reliability basis) but when injecting in to the manifold it becomes a very critical matter (especially if high power increases are aimed for) and you'll be in virtually unknown territory, because I only know of a handful of of people who have gone this route and most of them will not be prepared to part with the knowledge they gained in doing so.

I stated above I'm no expert on these matters BUT I've yet to read anything from anyone else who is or who even knows as much as I do about these subjects, so I wouldn't put much store in anything you read on the web.

I hope I am in the 0.1% of diesel owners Trev.

All I know, from a non mechanical point of view, is my car goes like s**t off a shovel on the methanol system. However, I do understand why it needs water, so I will never run more than a 50/50 mix in it. I am hoping my new mapping will be sorted end of this week (some non NOS/Water-meth related issues) and I will fully be able to use my setup.

I do however plan to install my nozzle in the inlet manifold so that water/meth goes direct into the inlet at the point of injection and not wind it's way through my intercooler system for a while before. All long term plans.

I am curious what you mean about a high octane fuel, Trev. Obviously diesel "octane" is the cetane rating of diesel, and supposedly fuels like Shell V power diesel and BP ultimate diesel give more of this (I have tried it and found less power & economy on it! ) I have found adding an additive into the fuel called Millers Diesel Sport 4 does really help with smoothness & power delivery. Unsure what exactly that stuff is doing but I can run my car on any old diesel and it will run well. I have also heard about people who add a couple of litres of unleaded in with a tank of diesel. Supposedly gives a bit of a kick.

I also know very little about Diesel but,

Cetane and Octane are almost opposites.
We all know Octane is the knock limit of fuel, ie how long it will resist self ignition.
Cetane is a measure of how quickly a fuel will self ignite.
Ordinary diesel should be around 47 Cetane, Ultimate etc is supposed to be 55 Cetane.
ignition speed doesn't improve beyond around 55 Cetane apparently.
Higher Cetane intended to get burn going earlier and therefore be more complete.
A fuel with high Cetane rating will have a low octane rating and vice versa.
I'm not sure this is a good thing in an engine pushed close to detonation by other factors.

I have also noted that my modified Diesel runs much better on cheap diesel. It feels very flat on Ultimate.

Also running rich on a diesel can cause excessive EGT's

Also I wouldn't want ANY petrol running through my High pressure diesel pump!

TDIfurby, what nos/water/meth issues have you discovered?

AFAIK, adding petrol in a diesel car offers no gains. I did use some when running on veg oil but was for thinning purposes during extreme cold weather.

If only other "experts" would give the technical reasoning behind their argument. Too many say you should limit the methanol to 50% or it will cause damage but fail to state why exactly, other than cite reasons such as higher compression, heat etc. Forgive me for stating the obvious but isn't that the expected effect of increasing power?

Yes, I agree petrol is octane rated - it's ability to resist auto-ignition, whereas diesel is cetane rated - it's ability to auto-ignite. What I don't understand is the effect of methanol (which they say increases petrols octane rating) on diesel fuel - is cetane value lowered? And mix water into the equation leaves me totally lost.

Ok, I understand that seriously overfuelling a diesel will raise EGT's through the roof so the first mod I'll make is to hook up a gauge. I'll be monitoring the exhaust temps and if it proves that going over 50/50 water/meth mix increases EGT's too far I'll back it off but with the little info I have currently, I can't exactly see why I shouldn't go higher. To add to my confusion, no-one has factored in quantity (ie 100ml/min vs 50ml/min) which I suspect would really mess up the calculation?

I guess I've been spoilt by WON where you simply find the correct jet ratio's, regardless of total flow.

Well today is a good day because I learned something new (thanks IDP) about diesels.

Although we've worked on increasing the power from diesels, we've had no need to monitor such things as EGTs, so I can't be sure about the following statement but I see and have experienced, no reasons to believe that adding more fuel would increase the EGTs.
My reasoning for being dubious about this claim, is that a diesel will belch out black smoke (or inadequately burned fuel), and I'd expect that to mean less heat was produced and any heat that was produced would be reduced by the cooling effect of excess fuel taking it away.

If it does then its the reverse of a petrol engine, which obviously doesn't prove the case either way but I think it would be strange if that were the case.
I can see why adding methanol would raise EGTs and I wonder if the 2 scenarios have got mixed up.

BTW our very technical member who covered the O2 sensor issue, also gave an insight in to how EGT should be interpreted but that was for petrol engines and 'may' not apply to diesels.

Hi Mike,I got a book called Tubocharging performance Handbook By Jeff Hartman,don't know much about the guy but it's a good read and has an interesting diesel section.lots of how's and why's.Also some about water injection..
ISBN978-0-7603-2805-7.
Might be some use to you,also some hopped up diesels in there that may lead you to more info.

Jeff seems a decent and reasonably knowledgeable guy who claims to have a good engineering background and just for the record is American.

He's just finished a book on nitrous and has included my products in it (haven't seen or read it yet, so I don't know how well he's dealt with them), so that's a first for an American book - I must be making an impression over there at last!!!

Looks like I'll have to buy this book as well as his nitrous book and with any luck I'll learn something from both.

It's worth a read,if only for the story about the GM skunk work's 2.0l ecotec project.From 140hp stock to 1400hp turbo(with nitrous inbetween).Some great pictures too.Full on petrol head porn

I have yet to have any negative issues. The only thing I have noticed which is a consequence of me placing the nozzle too far from the inlet, is when I get off boost, there is a lag of nil boost but there is still some water/meth in the IC system. This causes a momentary shuddering as it goes into the engine, when it is not under load or boost. I guess the engine under load can consume much better, and without it being under load, the engine is essentially partially hydrolocking, which cannot be good!

Trev - the "no more than 50/50" thing came from stories on TDIclub, and also one from here where that chap ran 100% methanol and got in your bad books. I suppose when I think of both parts of an equation doing an equal job, I want them in equal proportion, hence 50:50. It could well be that with my high flow nozzles, maybe a 30 meth / 70 water mix would be better. I do know however, that before I got methanol I ran my system on 100% water and although good, was still a bit flat. Once I got a 50% mix in there the difference was clear as day. I can only put that down to the methanol helping as well.

Re: the fuel additive, I copied this off the Millers website. I doubt they will give away any ingredients.

DESCRIPTION:
High specification diesel fuel treatment for enhanced combustion efficiency and engine cleanliness.

APPLICATION:
For use in all diesel vehicles including modern Euro IV compliant engines.
By addition to fuel in the ratio 1 part to 1000 parts [1 ml/L]. May also be used at double strength for additional performance.

USER BENEFITS:
• Diesel Power Sport 4 is a modern state of the art fuel treatment that is suitable for all diesel engines, especially Euro IV emission-compliant vehicles, which also provides a tangible improvement to vehicle performance.
• Gives “better-than-new” performance.
• Features a unique combustion efficiency improver and Cetane booster providing extra power and torque.
• Improved throttle and engine response at lower revs.
• Protection of fuel system components against wear, with specially added lubricity enhancers.
• High specification detergency additive for prolonged injector cleanliness.
• Engine smoothness, noise reduction and fuel savings confirmed by users.
• Inproved combustion and engine cleanliness drastically reduces emissions.
• Provides fuel system corrosion control.
• Prevents fuel from ageing.

PERFORMANCE PROFILE:


TYPICAL CHARACTERISTICS:
SAE Viscosity Grade ... n/a
Specific Gravity @ 15°C ... 0.936
Kinematic Viscosity @ 100°C ... n/a
Kinematic Viscosity @ 40°C ... n/a
Viscosity Index ... n/a
Pour Point °C ... <-10
Flashpoint °C ... >60
Cold Crank Viscosity ... n/a

Trev,
On the EGT/rich mixture question, I'm thinking out loud here and NOT stating anything,
If Soot (black smoke) is the result of incomplete combustion of fuel, why is the fuel not completely burned?
Not enough oxygen or, not enough time, or both.
Diesel combustion is started with injection timing just as petrol combustion is started with Ignition timing (spark advance)
If you heavily retard ignition timing on a petrol engine EGT's go through the roof,
this is the reason retard can only be used for a relatively small amount of traction control power reduction before spark cutting has to be used. (something I have good experience with)
If the high EGT is caused by the burn occuring later in the stroke with less energy being put into pushing the piston and ending up going out of the exhaust as heat then could it be that,
A diesel that is over rich due to not enough time to burn all the fuel quickly enough as opposed to not enough oxygen, will also still be burning later in the stroke and also create extra heat in the exhaust?
What do you think?

Liking that, IDP.

I have a good EGT gauge in my car and have noticed a couple of things.

1) My water/meth has no EGT impact despite the extra power. If anything it is lower. I suspect this is a combination of the methanol (more fuel = higher EGTs) and the water (cooler intake air = lower EGTs) working together to tame EGTs whilst still giving a good kick of power.

2) NOS lowers EGTs too. Like the water, I believe this is because of the icy cold temps it is injected at. I bet it is a better "boost cooler" than water in reality.

In regard to EGTs in general I have noticed along my modding path, that having the least restrictive intake system, and exhaust system, as possible helps. It seems the less time air/fuel spends in the engine the better for EGTs - possibly more on the exhaust side, than intake side (I suspect)

I have to admit to really love derv tuning (VAG TDI specific) and like taking things to new areas.

Just on the EGT w/Nitrous front; I've seen both higher and lower EGT's when on nitrous (different engines/cars) and the way I see it, it all comes down to the completeness of combustion. All engines will run different timing values when on nitrous when compared to the same engine off nitrous (especially if they're non-WON kits) and different amounts, types and methods of introducing extra fuel (if any).

While the commonly held belief is that using nitrous makes your intake cooler and your exhaust hotter, I've seen exceptions that prove (test) the rule.

Couldn't agree more and the ONLY thing anyone with any real knowledge about high performance engines can say for sure is that they can't say anything for sure.

There are just too many variable to make ANY sweeping statement that applies to ALL applications.

If you ever hear/see an 'expert' make such a statement, you can be sure he is NOT an expert.

The 50/50 advice actually came from the devils own forum as part of their "general advice" to allcomers as I believe it covers their arse in case of engine damage as well as the pump manufacturers. I also suspect it's based on the maximum flow rate (nozzle size in Gallons Per Hour) for a given diesel engine.

So I'm really pleased you stated the above as that is exactly in agreement with what my common sense is telling me, (lacking in any real knowledge on the water/meth subject). Just because 3GPH is the maximum theoretical optimum flow for my engine doesn't mean I want to spray all 3GPH - none of the "expert advisors" I'd queried seem to consider this possibility at all.

Like you admit Trev, I can only assume it's also outside their comfort zone too but rather than admit it as you have done, they appear to pretend that one argument fits all scenarios. First I was told that thorough tests showed how much damage can be done but when pressed for that test data, I was told nobody would do that because it's common sense not to, they value their engines. I gave up asking in the end.

Hi Nige, are you selling your copy now you've read it?

You wont find many people willing to admit their limitations, especially when its related to something they are selling and most will concoct BS stories to support their limited knowledge, because its cheaper than learning the facts.

That is my understanding.
Correct
From what I can tell, the EGTs will rise when the diesel engine is under heavy load such as hillclimbing, towing or general hooning around on full power. Tuning advice (basically increasing fuelling) warns that EGT's will rise rapidly if overdone. However, I'm slowly coming to the conclusion that a lot of this diesel "theory" I'm picking up relates to huge american engines which may not be transferable to my smaller european car.
I can't envisage the fuel not having enough time to burn providing there's adequate oxygen and in the water/meth debate, because of nitrous I assume my engine will have all the oxygen it needs so I can't see my state of tune being overly rich if at all.

Another factor is that meth will not fuel a diesel engine, it still needs the diesel to auto-ignite so I can't see detonation being a major concern of too much meth though I'm crying out to be proved wrong!

From what I'm aware there are 2 different types of diesel engine, the big truck motors fall in to one category and small car engines fall in to the other and I'm quite sure that the principles that apply to one do not apply to the other.

Methanol can self ignite if the compression and heat are high enough which is why water is needed to prevent that I believe.

Just been reading about the Banks Power "project Sidewinder" an LSR pickup truck.
Managed to set a 2 way bonneville record of 213mph,not one mention of water/methanol injection i'm afraid.
In fact in the whole section dealing with "hot rodding" diesels in Hartman's book,while both Nitrous and propane are covered,there is nothing about water injection,methanol or mixing petrol with your diesel. It would seem that diesel's are a lot more complicated than I appreciated,so much so that spark ignition engine knowledge is completely useless.

yes - I have been amazed by some of the Cummins/Duramax powered trucks over in the N/A. 1000+hp through twin turbo'd V8/V12 diesel motors in excess of 6, sometimes 7 litres. From what I can tell their principle tuning involves getting the best turbos and getting as much fuel in as possible, with lots and lots of black smoke.

Tuning here seems to involve much "cleaner" power, perhaps due to our stringent emissions laws or the ASBO nature of having a real smokey exhaust (my ASBO is in the post to me )