Turbo delay.

[boosted331]

Originally Posted by SaabJohan

The wastegate only opens when there is a certain pressure in the intake or where ever you take the reference from. It doesn't take turbocharger speed into count (only a few racing turbos are fitted with turbocharger speed sensors).

The wastegate may also not handle the flow, and note that it's a diesel that we talk about and they usually don't use wastegates since they aren't unstable like gasoline engines (which is because the latter are lambda controlled).

I wonder how many people that have bought nitrous for diesels only to find out that it doesn't work?

What are you talking about, seriously. Turbocharger RPM is almost directly related to boost pressure. Increase shaft speed, increase boost, it's a pretty simple phenomenon. You increase the exhaust flow, it spins the turbine wheel faster, makes more boost, if the gate is big enough it bypasses more exhaust, if it isn't big enough you get boost creep, pretty simple. I don't know what the hell you're talking about, but it doesn't really make sense.

Secondly, I don't know about you but every single diesel I've seen that doesn't use a variable geometry turbo does use a wastegate, to prevent overspinning the turbo, just like you mentioned in the first part of your post

I wonder how many people have tried to make posts on here to sound smart-assy, only to discover they're totally wrong? Bully Dog makes diesel performance parts. They have a nitrous kit for diesels. Nitrous express has a kit specifically for diesels (http://www.nitrousexpress.com/News/NXd.htm). NOS makes a nitrous kit specifically for diesels (http://www.jegs.com/cgi-bin/ncommerc...81&prmenbr=361)

What's that again about nitrous not working on diesels?

[forcefanajd]

Originally Posted by boosted331

What are you talking about, seriously. Turbocharger RPM is almost directly related to boost pressure. Increase shaft speed, increase boost, it's a pretty simple phenomenon. You increase the exhaust flow, it spins the turbine wheel faster, makes more boost, if the gate is big enough it bypasses more exhaust, if it isn't big enough you get boost creep, pretty simple. I don't know what the hell you're talking about, but it doesn't really make sense.

Secondly, I don't know about you but every single diesel I've seen that doesn't use a variable geometry turbo does use a wastegate, to prevent overspinning the turbo, just like you mentioned in the first part of your post

I wonder how many people have tried to make posts on here to sound smart-assy, only to discover they're totally wrong? Bully Dog makes diesel performance parts. They have a nitrous kit for diesels. Nitrous express has a kit specifically for diesels (http://www.nitrousexpress.com/News/NXd.htm). NOS makes a nitrous kit specifically for diesels (http://www.jegs.com/cgi-bin/ncommerc...81&prmenbr=361)

What's that again about nitrous not working on diesels?

yea i definately have to throw the bull shit flag on him too...definately

[CBFryman]

Originally Posted by boosted331

What are you talking about, seriously. Turbocharger RPM is almost directly related to boost pressure. Increase shaft speed, increase boost, it's a pretty simple phenomenon. You increase the exhaust flow, it spins the turbine wheel faster, makes more boost, if the gate is big enough it bypasses more exhaust, if it isn't big enough you get boost creep, pretty simple. I don't know what the hell you're talking about, but it doesn't really make sense.

Secondly, I don't know about you but every single diesel I've seen that doesn't use a variable geometry turbo does use a wastegate, to prevent overspinning the turbo, just like you mentioned in the first part of your post

I wonder how many people have tried to make posts on here to sound smart-assy, only to discover they're totally wrong? Bully Dog makes diesel performance parts. They have a nitrous kit for diesels. Nitrous express has a kit specifically for diesels (http://www.nitrousexpress.com/News/NXd.htm). NOS makes a nitrous kit specifically for diesels (http://www.jegs.com/cgi-bin/ncommerc...81&prmenbr=361)

What's that again about nitrous not working on diesels?

Variable Geometry turbo thats what its called....

[SaabJohan]

Originally Posted by boosted331

What are you talking about, seriously. Turbocharger RPM is almost directly related to boost pressure. Increase shaft speed, increase boost, it's a pretty simple phenomenon. You increase the exhaust flow, it spins the turbine wheel faster, makes more boost, if the gate is big enough it bypasses more exhaust, if it isn't big enough you get boost creep, pretty simple. I don't know what the hell you're talking about, but it doesn't really make sense.

Secondly, I don't know about you but every single diesel I've seen that doesn't use a variable geometry turbo does use a wastegate, to prevent overspinning the turbo, just like you mentioned in the first part of your post

I wonder how many people have tried to make posts on here to sound smart-assy, only to discover they're totally wrong? Bully Dog makes diesel performance parts. They have a nitrous kit for diesels. Nitrous express has a kit specifically for diesels (http://www.nitrousexpress.com/News/NXd.htm). NOS makes a nitrous kit specifically for diesels (http://www.jegs.com/cgi-bin/ncommerc...81&prmenbr=361)

What's that again about nitrous not working on diesels?

Turbocharger speed, if we talk about the compressor relates to pressure ratio and airflow, have you ever seen a compressor map with the shaft speeds litsted? If you take a look at one you will notice that shaft speed tend to increase at high flow rates without using high boost pressures, so when not using oversized turbochargers there is a risk of overspeeding the turbocharger. The thing is that when you overspeed a turbocharger it's hardly ever noticed since most people don't have the sensors for measuring the turbo speed.

Today many diesels are equipped with variable geometry turbines. Wastegates have been used on some basicly at later years to increase low speed torque (by allowing a smaller turbine/turbocharger), diesels are stable and do not require a wastegate, which is why they were the most common application for turbochargers (the wastegate was introduced on the automobile market on the late seventies for use in gasoline engines).
The wastgates that are found on some turbochargers for diesels are usually smaller than wastegates for gasoline engines and are not designed to handle high flow rates.

All wastgates work by when reaching a certain pressure, often called "cracking pressure", the wastegate lifts off from its seat. The maximum boost pressure will then depend on, except on the cracking pressure, the amount the wastegate will open when the pressure increase. The cracking pressure depends on the spring load when the wastegate is closed and the amount the wastegate is opening on the spring rate, that if we exclude the wastegate deisgn and position. So maximum boost is basicly a balance between exhaust flow and wastegate lift.
A wastegate can also open because of a high exhaust pressure, this can sometimes occur when using small wastegate actuators. High performance units often use much larger actuators in comparison with valve area and harder springs and therefore rarely opens becuase of exhaust pressure alone.

The most simple way to increase power on a diesel engine is to increase the fuel flow, diesels work with an excess of air and there is oxygen enough to burn more fuel. Remember that diesels doesn't use a throttle plate and consume all the air that they can, only regulating torque by the fuel flow. The only reason that more fuel isn't added original is because of exhaust emissions and fuel economy (leaner = more efficient).
Adding nitrous will do nothing, it will only increase the excess of oxygen unless the fuel flow is increased, and you don't increase fuel flow on a diesel like with a gasoline engine where you simply can increase fuel pressure or add an extra injector in the intake. Adding the extra fuel is the complicated part when tuning a diesel engine, increasing the oxygen can simply be done by increase the boost pressure as the engine will not suffer from engine knock like a gasoline engine.
Adding nitrous is basicly to waste money when one can increase boost instead, nitrous doesn't offer the simplicity that it offers on gasoline engines.

[CBFryman]

^^nitros still works...dumbass...otherwise so many companies wouldnt sell it...granted nitros injected with propane is twice as good...but nitros still works...

[Neutrino]

OK lets make this clear, this section of the forum will be completelly kept Civilised, so no shit talk nobody gets Owned and you absolutelly Don't use Name Calling(hint CBFryman)

You want to disagree feel free, but keep it clean and technical. SaabJohan made his posts without personally attacking any one of you and I expect the same courtesy in return.




Now back to the disscussion. Normally yes it seems that nitrous does absolutelly nothing on a diesel engine unless you dump so much fuel in it that it simply cannot get enough air in to compensate and you overfuel it. In that case nitrous might compensate. Although it would take quite an insane fuel system to provide that much fuel.

http://www.bankspower.com/tech_nitrousoxide.cfm

[CBFryman]

Quite and insane fule system? every now and then my grandfathers diesel will belch black smoke...and its brand new....and so will his johndeer tractor...but the tractor isnt turbo....along with every big rig on the road has a valve and then the exaust pressure is grate enough it releases big clouds of butt smelling smoke....im sorry for calling SaabJohan a dumbass but i hate it when people are wrong and stay persistantly wrong on otherwise common knowlege...yes i know i can be wrong often but if i am proved otherwise i do not persist...it has been proven over and over that nitros oxide can help any internal comustion engine if enough fuel is previded....

[Alastor187]

Originally Posted by CBFryman

it has been proven over and over that nitros oxide can help any internal comustion engine if enough fuel is previded....

I was under the impression that one of the most significant challenges of compression ignition engines was producing a homogenous air fuel mixture during the short injection period.

[Neutrino]

Originally Posted by CBFryman

Quite and insane fule system? every now and then my grandfathers diesel will belch black smoke...and its brand new....and so will his johndeer tractor...but the tractor isnt turbo....along with every big rig on the road has a valve and then the exaust pressure is grate enough it releases big clouds of butt smelling smoke....im sorry for calling SaabJohan a dumbass but i hate it when people are wrong and stay persistantly wrong on otherwise common knowlege...yes i know i can be wrong often but if i am proved otherwise i do not persist...it has been proven over and over that nitros oxide can help any internal comustion engine if enough fuel is previded....

The black smoke is not cause normally by overfueling. It is caused by improper combustion and the resulting unburned hydrocarbons and is very common especially on old diesels.

Overfueling will cause even more black smoke but its not the common cause in a regular diesel.

Also overfueling a diesel happens only in very highly modded diesels. and yes it should quite an upgrade of the fuel system.


http://www.bankspower.com/tech_nitrousoxide.cfm

To begin, a turbo-diesel has no air throttle. It is free to intake as much air as it can draw, or the turbochager can supply, on every intake stroke. Therefore, hot rodding the diesel is a matter of supplying the engine with as much fuel as can burned by the air available at maximum power. In fact, you can overfuel a diesel in the quest for power.........

Let’s assume you’ve modified your turbo-diesel to the point that it is overfueled and belching black smoke under a full load. What can you do? One solution is to add nitrous oxide injection, but in this case, you would not add extra fuel because you’re already too rich.

When you think about it, adding nitrous oxide injection to a diesel is easier than adding it to a gas engine because you don’t have to mess with adding extra fuel. In fact, there’s no point in doing it unless you’re already in an overfueled condition.

Look at that quote it is clear that nitrous should be used only after you overfueled your diesel. So SaabJohan was on the right track he just did not think of the extreme case of pushing your diesel so hard that you "flood" it with fuel. And again take this advice and do not disregard what Johan is telling you, he is very very knowlegeable.

[SaabJohan]

The thing is that with a diesel you can when you overfuel it increase the boost instead as it isn't knock limited.

There are diesels running extreme boost pressures, the highest that I've heard of is around 17 bar (246 psi) using three stage turbocharging. That case is a little extreme but since most diesels for cars aren't using that high pressures it isn't that difficult to solve.

"But if the turbo isn't large enough" you might think, well in that case you're in trouble even if you choose use higher boost or nitrous as both will overspeed the turbocharger.

[CBFryman]

^^ we already established that 99% of diesels today use either veriable geometry or wastegates....and in order to increase boost you would have to make the turbo spin faster so you are contradicting yourself...

[Jet-Lee]

I've read this entire thread from start to here, and CBF, I don't understand how you think SaabJohan is contradicting or wrong?! What he is saying makes perfect sense to me, not to metion, I've also learned a little more of what makes a diesel tick...

[SaabJohan]

Originally Posted by CBFryman

^^ we already established that 99% of diesels today use either veriable geometry or wastegates....and in order to increase boost you would have to make the turbo spin faster so you are contradicting yourself...

I've never contradicting myself. Today most diesels for passenger cars are using variable geometry, a few are probably using wastegates. But if we goes back a few years in time that wasn't the case. And if we look at larger diesels many of them, and still today are using fixed geometry turbines without wastegates.

Turbocharger speed isn't as easy as increased speed gives increased boost, not that I have the slightest clue what you are talking about. Have you heard about turbocharger matching?

[CBFryman]

yes i have head or turbo maching...but it is a known fact that the faster you spin a turbo the more boost it creates...and since all newer non big rig diesels are using variable geometry turbos or wastegates why did yo ueven begin to state that there was no boost controll on diesels....

[958Rocky]

saabjohan was talking about making massive amounts of boost. Try boosting 30 psi on a T25, you can't.

Cbfryman its cool that your posting and learning but stop acting like you know everything when here and in the honda forum you've been proved wrong repeatdly.