Naturally aspirated diesels

[90Mav]

So, i see a lot about blown diesels on here, is there anyone here who has modified a N/A diesel for signifigant power gain?

and yes I KNOW it would be easier/cheaper/more efficient to turbo...

i like N/A engines (they sound better ) and would like to see 200bhp from my TD42.

im not an expert on diesels...

but looking at the motor:

inlet manifold looks restrictive.. could it be replaced by a fabbed tuned length runner manifold and plenum? (like tripple webbers if u see what i mean)

port matching, and cleanup of bowls?

bigger valves?
custom ground cam? ( a roller cam would increase valve speed without changing profile)

how about lpg injection to get a better burn of the diesel?
possibly with water/ methanol injection to keep the exhaust temp in check?

what about burn time vs injector pump timing? (like i said, im no expert, but this would surely be critical after major mods?????)
..also longer rods would affect dwell at TDC possibly increasing torque at higher rpm?

lighter pistons?? ( have seen high compression engines 15:1 running straight lpg with light pistons, so why not a diesel )?

offset grinding of crank to slightly increase displacement?

any one done something similar? or know someone who has?
somebody must have gone rank on a n/a diesel.

please don't tell me to get a turbo.. i know after spending 10g's on a n/a diesel it will still be wasted buy a stocker with a $1200 turbo but it wouldn't be neally as cool

any natrually asperated thaughts would be appreciated...

Rhys

[badger]

injecting lpg, or nos or something like that.
even more compression head work and cams do work well but diesels by nature will not respond to na mods as well as a turbo

so in essence you are waisting your time and no na diesel will ever sound as cool as a turbo diesel
good luck tho

[Wish I had coils]

I say go for it would be good see you show some people what you can do with an old oiler be great to see
Never the less turbo sound awesome with the whistle and go hard to
TURBO i just want one

[mattstar]

I'm no expert but from my limited experience high performance motors require high maintance, why would you want to spend so much and then continue to spend big$$ maintaining something that "would be wasted by a stoker with a $1200 turbo"?

[Tapage]

You can make plenty of mods ..

More bore on the pistons, more compresion ( raise it up to 28:1 or so ), valvles, cam, and propane injection ..

But all o those mods gonna cost you more ( much more ) than a simple .. mmm you know what.

And anycase not sure you can reach 200 Hp from this engine ..

[ed.]

It would be awesome if you built it up N/A to 200bhp.
Really depends on your budget and how much of it you can DIY.

If you have a budget then go the turbo route IMO.

[tweak'e]

typically hot em up NA approach is to shift the torque up the rev range to increase horsepower. however with a limited rev range on a diesel there is only small improvement.

the only other way is to shove more air in by tuning intake/valves/cam. there is some room for improvement but its still only a few hp.

on an indirect injection motor you can play with precup sizes which changes how the fuel burns.

the only real way of getting any decent gain is simply give it bigger capacity eg bore it and stroke it. not a bad idea if your going to reco it anyway. however you got to watch how far you go. too thinner block walls and too lighter crank will end nasty really quickly.

light pistons will hurt reliability with 22:1 compression and it won't be doing the revs to warrant it.

lpg injection would help but remember the biggest drawback of NA is lack of air.

the other thing to remember is efficiency is probably go lower when your trying to burn lots of fuel so expect a decent increase if fuel consumption. turbo's tend to be a lot more economical for the amount of power produced.

[KiwiBacon]

It's doable. But the drivability wouldn't be there.

I found a figure of 270Nm at 2000rpm for your engine. If you can raise that to 300Nm with a few intake and exhaust mods, you need almost 5000rpm to make 150kw.
Holding 300Nm at 5000rpm is not an easy task.

A diesel turning at 5000rpm isn't a beautiful thing (unless you're talking Audi R10).

The father of a mate stuck a turbo on his 4.2 nissan safari and after some pump tuning on a dyno made 180hp (I think at the wheels). Just for some contrast.

[Dzltec]

The secret to your answer is in two parts, you need more air, then fuel.

More air is with valve size, inlet manifold design, camshaft profile and exhaust.

Fuel is a modded pump and injectors.

You could do this with just nitrous and fuel, it would cost a bit in the nitrous side of things but doable.

Longer stroke isnt really possible unless you want to redesign all of your engine components, ie rods, crank, pistons etc,

Are you talking power at the wheels or flywheel?

Im game if you are and want to supply an engine and a nitrous system.



Andy

[90Mav]

the only other way is to shove more air in by tuning intake/valves/cam. there is some room for improvement but its still only a few hp.

Ok. here is where i think the improvements can be made. Power is basically turning the chemical energy in the fuel in to HP right? so if i can increase the effiency of the burn to near 100% (propane injection) as opposed to 80% or so for a std pre combustion diesel there is 20% power ( say 90hp to 108 hp) and then increase VE to 100% or more as opposed to 75% ( 108 to 135 hp) without changing the peak torque rpm then your talking meaningful gains without hurting reliability. Add in a displacenent increase of 200cc or so and your talking 162 hp without changing the peak hp rpm. thats nearly double the torque without compromising reliability

Ok so then you comproise reliability..
say move peak hp from 4000 to 5000, then power increases fromm 168 to over 200 hp as long as you can keep VE ok...the trick would be to keep a flat graph, for drivability (drove a new triton TD recently... the power hit at 1700 and was gone by 3000, so turbo diesels have a limited power band too..)

and sure this setup wouldn't be as econimacal as a TD but it would definatly SOUND better and i will post a sound file when i hit 200 BHP so you can judge. lol

light pistons will hurt reliability with 22:1 compression and it won't be doing the revs to warrant it.

Why not? as dielels dont have detonation like petrols, what is the limiting factor in compression ratio?? (the amount the engine can phisically withstand???) why the HD pistons in diesels (compared to high comp petrol engines?) is the exhaust temp in diesels that much higher than petrols? If so surely they could be made of a diffrent material?

anyway thanks for all the replies.

Rhys.

[Tapage]

2 Points ..

A Turbo Diesel engine ( intercooled ) with properly fitted and suited turbo could hold boost up to all range of rpm .. it depends on you ..

Newer engines are compromise between reliability and performance .. they are trying to get the max boost at lower rpm and let the engine stand " free " at hi rpm ..

But you can suit a turbo that start boosting ( producing ) at 1200 rpm and hold it to full boost at 2.5 and hold it up to 4k rpm ..

Of course you gotta get very streesed engine ..

With a lighter piston, and hig comp ( much more than 22:1 ) you are rising your EGT .. it means more temp in the comb chamber .. that it means more heat produced in all intake and head ..

More head .. less O .. = less power produced.

With a propane injection and maube some methanol or water injection you can drop some dregrees in your intake and can add more fuel .. even you cooling system can handle that ..

[mattstar]

Correct me if I'm wrong but isn't propane, lpg or nitrous injection all forms of chemical supercharging? and if that's so then it's not a N/A diesel which sort of defeats the purpose of spending all that time and money for a thirsty power plant that could make more from a turbo or supercharger?

You sound like you know what your talking about and done some research, So without any chemical injection is the power gain worth the effort and money for the "sound" taking into mind the running and maintance costs for building and a year of operation compared to say an internally modded and turbo'd 4.2 that could/would have more power and reliability?

[Tapage]

Reliability it's a interesting word when you get into the mods world.

I'm sure could be done .. by us .. ? not by me at least .. that's the reason after good our of reading in the net and books decide for the simple turbo intercooler way.

[KiwiBacon]

the only other way is to shove more air in by tuning intake/valves/cam. there is some room for improvement but its still only a few hp.

Ok. here is where i think the improvements can be made. Power is basically turning the chemical energy in the fuel in to HP right? so if i can increase the effiency of the burn to near 100% (propane injection) as opposed to 80% or so for a std pre combustion diesel there is 20% power ( say 90hp to 108 hp) and then increase VE to 100% or more as opposed to 75% ( 108 to 135 hp) without changing the peak torque rpm then your talking meaningful gains without hurting reliability. Add in a displacenent increase of 200cc or so and your talking 162 hp without changing the peak hp rpm. thats nearly double the torque without compromising reliability

A few problems with that.
Firstly propane doesn't increase burn efficiency, it's just extra fuel (with a large amount of hype and BS thrown around). Because the autoignition temp of lpg is lower than the precombustion temps in most diesels, the lpg autoignites (detonates) which is why people say it effectively advances timing while doing bad things to your engine.
Secondly the lpg you run into the intake will displace your much needed air. Not to mention legality issues with insurance etc.
Thirdly increasing VE to 100% is going to involve some pretty advanced resonance tuning that is only going to work well over a small rpm range.
I have heard the honda S2000 gets a VE of around 109% at some point in it's rev range, but take a stab in the dark at how many millions it cost honda to develop it to that level.

[90Mav]

A few problems with that.
Firstly propane doesn't increase burn efficiency, it's just extra fuel (with a large amount of hype and BS thrown around). Because the autoignition temp of lpg is lower than the precombustion temps in most diesels, the lpg autoignites (detonates) which is why people say it effectively advances timing while doing bad things to your engine..

Ok so i havent done much reasearch on the lpg thing.. but surely the burn effiency could be easily checked with exhaust gas analysis? and if the companys marketing these products havent done the analysis how can they make the claims?

Secondly the lpg you run into the intake will displace your much needed air. Not to mention legality issues with insurance etc

true, i hadn't thaught of that

Thirdly increasing VE to 100% is going to involve some pretty advanced resonance tuning that is only going to work well over a small rpm range. I have heard the honda S2000 gets a VE of around 109% at some point in it's rev range, but take a stab in the dark at how many millions it cost honda to develop it to that level.

True, however i have heard of old 308's getting over 100% on the strip (admittadly at over 6000rpm) and these blokes didn't even have computers...just a matter of trial and error, so with a computer, and someone who is good at maths(not me) surely 100% could be approached without 'too' much stuffing around at whatever rpm you liked?
admittadly it would only work at the set rpm (unless i made some variable length intake runners like the 26b mazda lemans cars had)

Hey call me a sucker for punishment, but i cant believe that NO ONE has built a fire breathing n/a diesel.

[HotFourOk]

Hey call me a sucker for punishment, but i cant believe that NO ONE has built a fire breathing n/a diesel.

Becuase it's cheaper, easier and more worthwhile to turbo them.

And after all that work, they will end up bolting a turbo on anyway.

And I strongly disagree that your n/a diesel will sound better than a slightly modified turbo diesel.

[zagan]

besides nos you could also try out water and methonal.


This will cool down the diesel as well, offer some cheap HP, cheaper than NOS anyway.

Some US diesels are running NOS and water/methonal systems.

[me3@neuralfibre.com]

A few problems with that.
Firstly propane doesn't increase burn efficiency, it's just extra fuel (with a large amount of hype and BS thrown around). Because the autoignition temp of lpg is lower than the precombustion temps in most diesels, the lpg autoignites (detonates) which is why people say it effectively advances timing while doing bad things to your engine..

Ok so i havent done much reasearch on the lpg thing.. but surely the burn effiency could be easily checked with exhaust gas analysis? and if the companys marketing these products havent done the analysis how can they make the claims?

Secondly the lpg you run into the intake will displace your much needed air. Not to mention legality issues with insurance etc

true, i hadn't thaught of that

Thirdly increasing VE to 100% is going to involve some pretty advanced resonance tuning that is only going to work well over a small rpm range. I have heard the honda S2000 gets a VE of around 109% at some point in it's rev range, but take a stab in the dark at how many millions it cost honda to develop it to that level.

True, however i have heard of old 308's getting over 100% on the strip (admittadly at over 6000rpm) and these blokes didn't even have computers...just a matter of trial and error, so with a computer, and someone who is good at maths(not me) surely 100% could be approached without 'too' much stuffing around at whatever rpm you liked?
admittadly it would only work at the set rpm (unless i made some variable length intake runners like the 26b mazda lemans cars had) :twisted:

Hey call me a sucker for punishment, but i cant believe that NO ONE has built a fire breathing n/a diesel.

Tuned inlet runners will give a pulse effect at certain frequency and it's multiples, giving free "boost" and possibly allow VE over 100% if inlet is very free flowing for the RPM. Ford does this with the EF falcon - dual length intake runners, butterfly between them. BUT (big BUT), it's only for a very narrow rev range. Ford set it up for 100km/hr cruise. In a diesel, it would be very limited in effectiveness. Autospeed did a heap of testing inlet runners years ago, and found some great results on the dyno. Extractors do the same thing, but for exhaust gases. 2 stoke tuned pipe does the opposite of extractors and shoves gas back in, they overfill the cylinder till fual/air flow into exhaust, then shove it back in with the returning exhaust pulse. Give over 30%+ extra, BUT, powerband with just a pipe is very narrow rev range. 2 Stokes use powervalves to broaden the frequency range somewhat, and smooth out the abrupt change.

All these things are basically 3-4psi boost. If you want to retain the exhaust note that badly, use a supercharger. Steal one from a commodore, it'll be oversized for your application.

Paul

[KiwiBacon]

Ok so i havent done much reasearch on the lpg thing.. but surely the burn effiency could be easily checked with exhaust gas analysis? and if the companys marketing these products havent done the analysis how can they make the claims?

Marketing is full of bogus claims. Hiclone anyone?

Check out the inlet tract on the later ford falcon 6 cyl's, they're variable length to hit resonance and max VE at as many points as possible. It may be possible to retrofit one to your engine.

[Dzltec]

Nos is only another air source, how else do you get more air in easily. Once you fit nitrous then you can add lpg or diesel to get your power.

If you can add 150 hp to a petrol as long as you have enough fuel, you can do it to a diesel as well. The power output will be determined by fuel delivery.


Andy

[nastytroll]

mercedes benz set 5 speed records in the early 80's with a nos injected deisel, fuel n oxygen is what makes power.
Also the supercharger from the commo is the right size, Eaton M90 or E90 works great, cant remember which is which but both fit, one is bottom output the other rear output. I have been in TD42's running both

[90Mav]

im thinking NOS might be a good first step, does anybody know the pros and cons of NOS in diesels?
would a fogger plate be the go? or multi point injection?

how big a shot would be relatively safe for a stock motor? im thinking it could take more than a fairly stock petrol v8, being of heavier construction?

How much is too much? as it wont detonate like a petrol engine

With a lighter piston, and hig comp ( much more than 22:1 ) you are rising your EGT .. it means more temp in the comb chamber .. that it means more heat produced in all intake and head ..

what is nos' effect on EGT? what if you controlled EGT with Water injection? more NOS? more Diesel? how far could you go with this?

what is the limit on how much NOS you are using, if these motors can make 200 rear wheel HP with a hair dryer, then why not 200 RWHP with NOS?

im thinking the TD42 will need the intake freed up to make 200RWHP~280BHP Nos or not?

as the inlet manifold has no throttle body or sensors, can it be easily replaced with a individual ram tube assembay feeding from a large plenum ? What effect does plenum design impact on the tuned ram effect?
it would have to have a plenum, to provide adequate filtration.

[zagan]

Look to the US for ideas with NOS and/or Water methonal systems.

Water/methonal will be the cheapest, it's basicly a bottle, a little water pump that injects the water mix to the air pipe, it's misted the better the mist the better it works.

The water cools down the air which increases power and the methonal helps the diesel to burn with the mist of water, this system can cause rust though.

On that pirate 4x4 site there's a post saying they use a car window washer soap as it has 30% methonal in it, which I thought was interesting, these systems are sort of sold like NOS shots as well.

All the NOS systems I've seen on Diesels are wet or dry injection systems.

[badger]

nos would be good if you only want one power run a week or so otherwise its gunna start getting dear real fast if you run round town squirting nos at every set of lights. especially once the cops catch u.

the other problem is you would have to tune more fuel into the motor to make use of the nos but then it would be over fueling when not on nos, this would cause egt issues.

i guess you could look into lpg fumigation to use when on nos or something like that but you are then forcing 3 different "fuels" into your motor and it would all become very complex for anything this side of wining 5 landspeed records

[rocknferoza]

Wasn't there a heavily modified n/a 2.8 diesel hilux dual cab that was meant to go harder then a turbo lux

I'm sure I read about it in 1 or 2 4by mags.



I reckon go for it but a turbo diesel will always sound better then an n/a diesel.

[zagan]

what about boring it out a bit wider,

I don't know what the deal would be with increasing the stroke of a diesel, you'd want as much compression as you can get and sortening the conrod might reduce the compression, I get the impression that the pistion has to be coming up to the deck for the diesel to burn corectly.

Maybe change the surface of the pistions, like hollowing them out a bit or changing the size of the grooves.

Also look into opening up the injector side of the cylinders.

You can also increase the gasket thinkness as well.

This would increase the total amount of air in the engine also giving extra power without any nos etc.

NOS is good but it will only last as long as the bottle is full, that's the main reason for diesels having turbos in the first place it's on-tap power all the time.


might be 4.* at the end of the day but would make more power than a 4.2.

[tweak'e]

bore out the block/sleeve's and offset grind the crank. either shorter rods or shorter pistons etc. you probably need custom made pistons.

not sure how much you can bore out but you might get it up to 5 litre.
certainly more power but reliability will suffer. the bore might be a bit thin and crank will be a bit weaker. for the power made, atmo diesels are hard on the crank (ie turbo diesels often use the same crank but 30-50% increase in power with no reliability issues) however you could make a custom crank ($$$$).

all in all, unless there are aftermarket parts available off the shelf, its going to be horrendously expensive for the small/medium power increase.

if your doing a reco anyway boreing it out to max oversize and useing standard oversized pistons is not a bad idea. but i would still turbo it

[90Mav]

ok im thinking NOS would be a good first step.
i am presuming that more fuel cannot be introduced via a 'wet' system, as it would burn before the main charge?

so the only real option seems to be increasing the fuel delivered by the main injection pump.. obviously this extra fuel is only needed when NOS is activated.. what do you think is the best way to achieve this?

i know the TD42-TD6 nissan engines have electronic injection timing. and that rovers have boath electronic timing and fuelling, i believe the latter is using solenoid injectors though..

but if adding fuel is as easy as turning a screw on the back of the injector pump, the surely extra fuel could be switched resonably easily?

anyone have experiance with adding extra fuel to diesels on a as needed basis? (hopefully without playing with 1500psi pressure)

[HotFourOk]

ok im thinking NOS would be a good first step.
i am presuming that more fuel cannot be introduced via a 'wet' system, as it would burn before the main charge?

so the only real option seems to be increasing the fuel delivered by the main injection pump.. obviously this extra fuel is only needed when NOS is activated.. what do you think is the best way to achieve this?

i know the TD42-TD6 nissan engines have electronic injection timing. and that rovers have boath electronic timing and fuelling, i believe the latter is using solenoid injectors though..

but if adding fuel is as easy as turning a screw on the back of the injector pump, the surely extra fuel could be switched resonably easily?

anyone have experiance with adding extra fuel to diesels on a as needed basis? (hopefully without playing with 1500psi pressure)

Doesn't a boost compensator do this kind of thing for turboed diesels.
I thought when the turbo creates pressure in the manifold, the injector pump pumps more fuel into the motor to match the increase in air.

[cloughy]

ok im thinking NOS would be a good first step.
i am presuming that more fuel cannot be introduced via a 'wet' system, as it would burn before the main charge?

so the only real option seems to be increasing the fuel delivered by the main injection pump.. obviously this extra fuel is only needed when NOS is activated.. what do you think is the best way to achieve this?

i know the TD42-TD6 nissan engines have electronic injection timing. and that rovers have boath electronic timing and fuelling, i believe the latter is using solenoid injectors though..

but if adding fuel is as easy as turning a screw on the back of the injector pump, the surely extra fuel could be switched resonably easily?

anyone have experiance with adding extra fuel to diesels on a as needed basis? (hopefully without playing with 1500psi pressure)

You can add all the fuel you like, but when its pissing black soot, its not burning, you need more air That's what a turbo does