Using EGT as a timing adjustment aid?
Moderators: jsmcortina, muythaibxr
-
jakobsladderz
- Experienced MS/Extra'er
- Posts: 170
- Joined: Tue Mar 15, 2005 10:08 pm
- Location: Ballarat, Australia
The 950C value came from an engine tuner I know down in melbourne (so don't take it as the gospel truth) but is based on giving a safety margin to temperatures that will melt exhaust valves and such. Given that the limit to how lean an engine can be run at full power is when things start to melt, but that running leaner (up to ~13.5-13.7:1) will make more power, EGT can have it's place.. There must be some info on the net on tuning with egt...
Exeter: (noun) the nut or bolt always left over after putting something back together (Douglas Adams, The meaning of Liff)
To : fiat132
Thanks for the compliments ,
I figure that all this stuff I've packed into my brain over the years
ought to be put to good use by sharing it
If you "don't agree with all the stuff" it's only because of three things :
1) Misunderstood words .
2) Extenuating curcumstances , (not ALL factors are out on the table or not all factors are known) .
3) You have had certain experiences where something worked or didn't work and
you applied the wrong reason as to WHY it happened that way .
You can't buy experience , so I'm offering mine so that maybe other folks
won't have to make the same mistakes that I did .
And of course , I could be wrong , I'm smart enough to always keep that in mind .
All the theory in the world means nothing if you can't make it work for you .
Enough of Me .
The bottom line is what counts ,
"Efficiency" is very simply how much output (Torque or Horsepower) do you get for
a given amount of input (BTUs or Therms etc.) .
When I said the
"Pumping Loses are Higher and efficiency is lower with a Turbo or Supercharger"
I was exactly correct , and I was only trying to get some of your
definitions straightened out so that as you progress in gaining more
knowledge and experience you would not be hampered by using incorrect
terms when communicating with other people ,
you may well know exactly how the concept works ,
but if you use the wrong terms to discribe it ,
other people won't understand you or will think you don't know what your talking about .
I was talking about the efficiency of the entire engine ,
you may have been talking about the efficiency of your Turbo .
"Pumping Loses" can be described this way ,
attach your engine to a stand and then attach a really big electric motor to the engine ,
spin the engine to 6000 rpm with the throttle wide open and no fuel ,
measure electrically how much horsepower the motor is having to generate
to spin the engine this fast , now you have a figure that is a combination
of Friction loses and Pumping loses ,
they are completely different but hard to measure separately ,
but it doesn't really matter ,
you are going to have both of them at the same time on any engine ,
and you know that port sizing is not going to affect frictional loses and
oil viscosity is not going to affect pumping loses .
Pumping Loses are usually created by a restriction , namely , poppet valves .
You can actually eliminate intake and exhaust pumping loses in certain RPM ranges by
tuning the intake runners and headers ,
but you will always have the compression stroke as a loss .
Pumping loses are not really what you wanted to talk about anyway .
You probably wanted to talk about something like "Flow" and "Velocity"
and then ran into someone who is trying to impress his college professor
with pages and pages of dollar and fifty cent words in his final exam ,
as far as I'm concerned the only use for this kind of thing is to get your
foot in the door of a really high paying job ,
in practical terms , it's much simpler than that ,
there are certain basic concepts ,
that when understood can get you more performance than you would believe ,
much more than most people wind up with
who throw thousands of dollars at their engines ,
it might look good , but that don't make it fast .
OK , I'll stop now .
It takes a certain amount of horsepower to spin a Supercharger ,
this is actually a "frictional loss" .
A Turbo adds pumping loses and a Supercharger adds friction loses ,
either way engine efficiency is reduced ,
but the power increase is much more than the additional loses .
There is no free lunch and no perpetual motion machine ,
you have to pay one way or another .
Turbocharging , "F1 cars" and the 2 lines :
If you were to really get into this you would find that achieving
turbo-nervana is really only practical in a very narrow RPM range and
with every part massaged by genius artisans and made out of "Un-obtainium".
In the real world , on the street , you need something that is going to be
bullet-proof , user friendly , easy to get parts for ,
and works over the broadest RPM range possible ,
this will make you much happier than something you've got to work on more than drive .
This certainly involves compromise , and you may even learn some
important principles by reading some of that esoteric stuff that will help
you to put together a "combination" that really rocks , but most likely
sticking to the basics and really making them work together the best you
can , is the way to go .
(that esoteric stuff might be worth some carisma points when bench racing ,
but I would be laughing at you under my breath)
Exhaust Stroke Pumping loses :
It is a fact that almost all engines (excepting some old farm tractors)
open the exhaust valve about 30degrees BEFORE the piston gets to the
bottom of the power stroke , at first , this seems like a terrible waste of
power , after all , the gases are still expanding and pushing down on the
piston right ? That's true , but you have to get all that pressure OUT of
the cylinder too , and there is only a certain amount of time to do it , so
you have to give things a head start so you can accelerate the exhaust
gases from zero to some ridiculously high speed in the exhaust manifold .
Also , this is not as bad as it seems , by the time the piston has gotten
that far down in the bore the volume of the cylinder has increased so
much that the rate of burning of the mixture has slowed down significantly
and the pressure in the cylinder has dropped also , and to top it off ,
now the crankshaft is in a position that does not give the piston very much
leverage to turn the crank , so it wouldn't be much of an advantage to
keep the exhaust valve closed and hold that remaining pressure in until
the piston was at BDC .
Now , the fact that the pressure has been reduced by increasing cylinder
volume which also causes a reduction in temperature , means that the
remaining mixture will continue to burn slower and much longer , which
means that it will still be burning and expanding as the piston pushes out
the last of the exhaust gases ,
which equals -- FLAMES OUT OF THE EXHAUST PORT !!!
The mixture is not done burning yet .
This is no big deal , and its been working this way for over 100 years ,
No one has been able to substantially improve upon the situation in all this time ,
so don't try to re-invent the wheel , its been done already ,
instead figure out why things are done the way they are done .
Thanks for the compliments ,
I figure that all this stuff I've packed into my brain over the years
ought to be put to good use by sharing it
If you "don't agree with all the stuff" it's only because of three things :
1) Misunderstood words .
2) Extenuating curcumstances , (not ALL factors are out on the table or not all factors are known) .
3) You have had certain experiences where something worked or didn't work and
you applied the wrong reason as to WHY it happened that way .
You can't buy experience , so I'm offering mine so that maybe other folks
won't have to make the same mistakes that I did .
And of course , I could be wrong , I'm smart enough to always keep that in mind .
All the theory in the world means nothing if you can't make it work for you .
Enough of Me .
The bottom line is what counts ,
"Efficiency" is very simply how much output (Torque or Horsepower) do you get for
a given amount of input (BTUs or Therms etc.) .
When I said the
"Pumping Loses are Higher and efficiency is lower with a Turbo or Supercharger"
I was exactly correct , and I was only trying to get some of your
definitions straightened out so that as you progress in gaining more
knowledge and experience you would not be hampered by using incorrect
terms when communicating with other people ,
you may well know exactly how the concept works ,
but if you use the wrong terms to discribe it ,
other people won't understand you or will think you don't know what your talking about .
I was talking about the efficiency of the entire engine ,
you may have been talking about the efficiency of your Turbo .
"Pumping Loses" can be described this way ,
attach your engine to a stand and then attach a really big electric motor to the engine ,
spin the engine to 6000 rpm with the throttle wide open and no fuel ,
measure electrically how much horsepower the motor is having to generate
to spin the engine this fast , now you have a figure that is a combination
of Friction loses and Pumping loses ,
they are completely different but hard to measure separately ,
but it doesn't really matter ,
you are going to have both of them at the same time on any engine ,
and you know that port sizing is not going to affect frictional loses and
oil viscosity is not going to affect pumping loses .
Pumping Loses are usually created by a restriction , namely , poppet valves .
You can actually eliminate intake and exhaust pumping loses in certain RPM ranges by
tuning the intake runners and headers ,
but you will always have the compression stroke as a loss .
Pumping loses are not really what you wanted to talk about anyway .
You probably wanted to talk about something like "Flow" and "Velocity"
and then ran into someone who is trying to impress his college professor
with pages and pages of dollar and fifty cent words in his final exam ,
as far as I'm concerned the only use for this kind of thing is to get your
foot in the door of a really high paying job ,
in practical terms , it's much simpler than that ,
there are certain basic concepts ,
that when understood can get you more performance than you would believe ,
much more than most people wind up with
who throw thousands of dollars at their engines ,
it might look good , but that don't make it fast .
OK , I'll stop now .
It takes a certain amount of horsepower to spin a Supercharger ,
this is actually a "frictional loss" .
A Turbo adds pumping loses and a Supercharger adds friction loses ,
either way engine efficiency is reduced ,
but the power increase is much more than the additional loses .
There is no free lunch and no perpetual motion machine ,
you have to pay one way or another .
Turbocharging , "F1 cars" and the 2 lines :
If you were to really get into this you would find that achieving
turbo-nervana is really only practical in a very narrow RPM range and
with every part massaged by genius artisans and made out of "Un-obtainium".
In the real world , on the street , you need something that is going to be
bullet-proof , user friendly , easy to get parts for ,
and works over the broadest RPM range possible ,
this will make you much happier than something you've got to work on more than drive .
This certainly involves compromise , and you may even learn some
important principles by reading some of that esoteric stuff that will help
you to put together a "combination" that really rocks , but most likely
sticking to the basics and really making them work together the best you
can , is the way to go .
(that esoteric stuff might be worth some carisma points when bench racing ,
but I would be laughing at you under my breath)
Exhaust Stroke Pumping loses :
It is a fact that almost all engines (excepting some old farm tractors)
open the exhaust valve about 30degrees BEFORE the piston gets to the
bottom of the power stroke , at first , this seems like a terrible waste of
power , after all , the gases are still expanding and pushing down on the
piston right ? That's true , but you have to get all that pressure OUT of
the cylinder too , and there is only a certain amount of time to do it , so
you have to give things a head start so you can accelerate the exhaust
gases from zero to some ridiculously high speed in the exhaust manifold .
Also , this is not as bad as it seems , by the time the piston has gotten
that far down in the bore the volume of the cylinder has increased so
much that the rate of burning of the mixture has slowed down significantly
and the pressure in the cylinder has dropped also , and to top it off ,
now the crankshaft is in a position that does not give the piston very much
leverage to turn the crank , so it wouldn't be much of an advantage to
keep the exhaust valve closed and hold that remaining pressure in until
the piston was at BDC .
Now , the fact that the pressure has been reduced by increasing cylinder
volume which also causes a reduction in temperature , means that the
remaining mixture will continue to burn slower and much longer , which
means that it will still be burning and expanding as the piston pushes out
the last of the exhaust gases ,
which equals -- FLAMES OUT OF THE EXHAUST PORT !!!
The mixture is not done burning yet .
This is no big deal , and its been working this way for over 100 years ,
No one has been able to substantially improve upon the situation in all this time ,
so don't try to re-invent the wheel , its been done already ,
instead figure out why things are done the way they are done .
'95 GM 4.3 Vortec V-6
Single Plane Intake w/ported GM Throttle Body
Ported Heads , stock roller cam retarded 8 degrees
MS-II 2.6 , V-3 board , MT 3.0
EDIS ignition , Innovate WB 02
250hp , 28mpg @60mph in a 2 ton wagon
Single Plane Intake w/ported GM Throttle Body
Ported Heads , stock roller cam retarded 8 degrees
MS-II 2.6 , V-3 board , MT 3.0
EDIS ignition , Innovate WB 02
250hp , 28mpg @60mph in a 2 ton wagon
-
rb26dett
- Master MS/Extra'er
- Posts: 497
- Joined: Tue May 24, 2005 11:34 pm
- Location: Auckland New Zealand
another thing to the guy suggesting that the holset exhaust turbine wouldnt like the heat of a petrol engine :
the turbine in those turbos is made from Inconel which can withstand some pretty extreme heat. theres a guy on the mx6 forums running msnse who made 400hp atw with 5 bent rods on a stock kl-de 2.5 mazda v6 with a holset hy35 diesel turbo. its now built with forged rods and pistons, and i'm looking forward to seeing his next dyno sheet. he put 10000miles on it before stripping 3rd gear.
just a fyi.
fred.
the turbine in those turbos is made from Inconel which can withstand some pretty extreme heat. theres a guy on the mx6 forums running msnse who made 400hp atw with 5 bent rods on a stock kl-de 2.5 mazda v6 with a holset hy35 diesel turbo. its now built with forged rods and pistons, and i'm looking forward to seeing his next dyno sheet. he put 10000miles on it before stripping 3rd gear.
just a fyi.
fred.
thanks for the reply jim...its really informative...i am sure evryone can use the experiences that you gained over the years...i am sure anyone who reads these posts would be really informed
fred, i worked at garret for a while and i know for a fact that their diesel turbines are made from different alloys.....i am not sure about holset...thats why some turbine shaft have differnt shaped ends...some have the shape of a bolt and some are triangled . i was always wondering why they did that until i went to garrett...i might be wrong with yours...i was just sharing my experience...i hope it works out fine
fred, i worked at garret for a while and i know for a fact that their diesel turbines are made from different alloys.....i am not sure about holset...thats why some turbine shaft have differnt shaped ends...some have the shape of a bolt and some are triangled . i was always wondering why they did that until i went to garrett...i might be wrong with yours...i was just sharing my experience...i hope it works out fine
just remeber guys....
any time you raise the inlet temps you raise the egts the same amount.
if your engine ran NA and hhad egt of 1000 then you could boost it to 15psi but if you are able to keep the inlet temps the same as it was running NA (intercooliong water injection etc ) then you would get the same egt....
thats what teh thermodynaic laws say...i am not sure what happens in practice....
any experiences??/
any time you raise the inlet temps you raise the egts the same amount.
if your engine ran NA and hhad egt of 1000 then you could boost it to 15psi but if you are able to keep the inlet temps the same as it was running NA (intercooliong water injection etc ) then you would get the same egt....
thats what teh thermodynaic laws say...i am not sure what happens in practice....
any experiences??/
-
Monotalonawd
- MS/Extra Newbie
- Posts: 15
- Joined: Sun Oct 03, 2004 12:16 am
- Location: Sherbrooke, Québec, Canada
- Contact:
As Fred suggested, the Holset has in fact a turbine wheel made from Inconel! I read a lot about custom turbo setups where the HX-35/HX-40 were used on petrol engine and never did they fail from heat. That's why I bought one!fiat132 wrote:a note to the guy with the talon...monotalonawd...if that turbo from a diesel engine then it wont last long...since diesel engines run cooler egts, the turbines made for them are made from different materials that wont last as much....
i have been through 2 turbos in the past 18 months....the materials are differnt...just thought i should mention it
If you read Mustang SVOs, turbo Volvos and turbo e30s (bmw) forums, you'll see that they have been used for years without any heat induced issues.I don't say every diesel turbos would work well in a petrol engine but in my particular situation (Holset), there's no worries!
I know for a fact that in the Dsm world, one of the most popular upgrades was the Mitsubishi 20G turbo that came from a diesel application; good for more than 400 whp.
Mine has been on the road for only one month (daily driven), but upon inspection, the HX-35 doesn't show any sign of fatigue on the exhaust turbine.
Back on topic, I'll have to read and re-read this thread a couple times in order to understand it all!!
88 BMW 535i, Holset turbo project
90 Eagle Talon TSi Turbo Awd
92 Eagle Talon Tsi Turbo Awd (sold)
90 Eagle Talon TSi Turbo Awd
92 Eagle Talon Tsi Turbo Awd (sold)