"Diesel shop" turbos and marketing..
10-04-2007 | 02:18 AM
#91
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From: Cummins Technical Center, IN
This maps shows up to .35kg/s for the stock charger.
Holset claims up to .46Kg/s here: http://www.holset.co.uk/files/2_1_1_3-Holset%20HX35.php
Does anyone know why the disparity exists? Are they testing different HX35 variants in each case?
EDIT: never mind, the BD graph shows an HY35, not an HX35.
10-04-2007 | 02:29 AM
#92
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From: Cummins Technical Center, IN
On my truck, advancing the timing with a healthy shot of fuel will light the turbo faster then using the stock timing. Remember until you are making boost, it a normally aspirated engine with an exhaust restriction. For max boost however retarding the timing on my truck will make more boost, but hp drops as drive pressure goes up.
Paul
Paul
The timing retard I was talking about was pretty severe. It has to be done a certain way to see a benefit. Bad on me for speaking in imprecise generalities.
10-04-2007 | 03:28 AM
#93
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From: Austria Europe
Alpine-- you are correct in the mass flow variance between gassers and diesels, as far as I can see.
+++++++++But we have to remember that it's not JUST the mass flow to the turbine-- it's the ENERGY. So a smaller mass at higher temp will drive the turbine as effectively as a larger mass at colder temp. This is why the turbine maps show "corrected" flow. It would be more accurage to go by drive energy (enthalpy), but corrected gas flow seems to approximate things closely enough
Gas engines have relatively constant EGTs, but wildly variable amounts of heat (thermal energy) because of the variable mass flow resulting from air throttling.++++++++++++++++++
**************Diesels have variable EGT and and wildy variable amounts of heat (thermal energy) at a relatively fixed mass flow (assuming constant RPM and such).**************
XXXXXXXXX The end result in the eyes of the turbine is about the same-- though they take two different paths, the gas and diesel meet at the same destination (more turbine power and hence, boost).XXXXXXXXXX
#########Unfortunately, the more "surplus air" you have, the more inefficient your engine becomes-- higher pumping losses, etc-- and the drive pressure will get very high quite early.##############
ÖÖÖÖÖÖÖÖÖÖÖ The "ideal" turbo setup for efficiency would hold EGT at a constant 1100-1200, providing just enough air to prevent meltdown. That would be very laggy too.ÖÖÖÖÖÖÖÖÖÖ
Justin
+++++++++But we have to remember that it's not JUST the mass flow to the turbine-- it's the ENERGY. So a smaller mass at higher temp will drive the turbine as effectively as a larger mass at colder temp. This is why the turbine maps show "corrected" flow. It would be more accurage to go by drive energy (enthalpy), but corrected gas flow seems to approximate things closely enough
Gas engines have relatively constant EGTs, but wildly variable amounts of heat (thermal energy) because of the variable mass flow resulting from air throttling.++++++++++++++++++
**************Diesels have variable EGT and and wildy variable amounts of heat (thermal energy) at a relatively fixed mass flow (assuming constant RPM and such).**************
XXXXXXXXX The end result in the eyes of the turbine is about the same-- though they take two different paths, the gas and diesel meet at the same destination (more turbine power and hence, boost).XXXXXXXXXX
#########Unfortunately, the more "surplus air" you have, the more inefficient your engine becomes-- higher pumping losses, etc-- and the drive pressure will get very high quite early.##############
ÖÖÖÖÖÖÖÖÖÖÖ The "ideal" turbo setup for efficiency would hold EGT at a constant 1100-1200, providing just enough air to prevent meltdown. That would be very laggy too.ÖÖÖÖÖÖÖÖÖÖ
Justin
++++++++++++ The trim of a turbine is always a compromise- you'll want short and steep blades for high mass flow and low delta T but long flat blades for extracting thermal energy at low mass flow and high delta T to get optimal efficiency. Hence a gasser turbine trim will look a lot different than a diesel trim. A gasser trim can rely on the fact that the turbine needs to be efficient for only a narrow delta T and the variance is mass flow. So in the eye of the turbine there is a big difference on how it gets it's energy. ++++++++++
******************* This holds true for a fixed RPM and almost fixed boost relation**************
XXXXXXXXX The turbine side sees enthalpy and extracts shaft horse power from that- but in a gasser that is throttled you must take into consideration that the boost before the throttle plate rises quickly if you are going lower than 100% load while the turbo is spooled- and one of the tricks of a nicely driveable turbo is to lose efficiency in the compresor map above the desired pressure ratio and thereby reducing the necessary shaft horsepower.XXXXXXXX (This is impossible on a diesel)
############ The surplus air is reducing efficiency- but not too greatly IMO because for the energy we invest in the pumping losses on the exhaust stroke we do recover (assumption) 70% that we can reuse to reduce the amount of energy used for the intake work, in higher boost situations the engine will produce torque on the intake stroke due to pressure differential between intake and crankcase. So the energy we lose is mainly due to the efficiency of the turbine and the charge air cooler-(which is necessary for emissions, and mainly power density- small engine with high output needs to stay together)##############
ÖÖÖÖÖÖÖÖÖÖÖ I think that does oversimplify. What we do want for efficiency is (for a given hp) the least possible remaining enthalpy in the exhaust gas and the least loss of energy through the cooling system including CAC and radiation. So basically I think that there is a point to the way that high efficiency diesels are built to make their most economic horsepower with very low EGTs because the enthalpy of the exhaust gas is some energy almost lost where we try to recover a part by using secondary systems like turbochargers ÖÖÖÖÖÖÖÖ
The trick to get a turbine that's much too big for a given situation to spool by dipping the timing to extremely late for a short time is rather old. It works kind of like an "afterburner" between the engine and the turbine. (And even that has been tried in some situations) - This timing dip is used on gasser turbo engines up to an extent of dipping the timing to 15 degrees past TDC for every third stroke in some applications if there is a quick positive change of throttle position. (This makes for a lot of enthalpy in the exhaust gas to spool the turbo) For a fixed timing engine timing it late will have the desired effect- but only for approximately the first quarter of a second while stepping on it (assuming HX35 and reasonable RPM on a B-series 5.9) but the tradeoffs like EGT, efficiency etc will slap you in the face for the rest of the engine run time.
I've reffered to the disadvantages of the turbo in a diesel quite enough- but now for the advantages from the view of the turbo.
First there is no practical limit to boost for combustion reasons- no pinging or detonation. Then any surplus air I produce is reconverted into horsepower with small losses -whereas with a gasser any surplus boost is caught by the throttle plate.
What I do see in this discussion is that there is a lot of theory about fixed operation parameter engines. But on the road we usually have a very wide band of operating parameters and the transient response makes the most important difference in actually driving the truck or pulling that trailer. EG a sledpulling truck with 1 k hp would be nice to pull a trailer up a mountain as long as we have enough cooling capacity. And as long as we have an almost constant slope, no turns etc. City driving that beast would be quite frustrating compared to a stocker with about 1/5th of the horsepower.
This seems to me is the main reason why a lot of aftermarket turbos do get reviews that do differ as wildly as you can see in the various threads on this board. I do also think that shooting for high horsepower is only good for dyno queens. On the road I am interested mainly in the "available NOW" horsepower and with a little consideration in the hp that are "to be at your doorstep in 2-4 seconds" Some sledpulling hp that are there after spooling for 30-50 seconds are completely worthless to me(on the road). That's where I see the chances of twins especially twins with lightning spoolup and still good high load+rpm manners.
AlpineRAM
(Whowillnextwriteaninterpretationofwarandpeacethat hislongerthantheoriginalifhedoesnotfindthemotivati ontodosomeworkquitesoon)
10-04-2007 | 04:05 AM
#94
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From: Cummins Technical Center, IN
Great post, Markus!
I honestly completely ignored the different turbine designs for for different circumstances. Thanks for pointing that out and teaching us. Wouldn't it be fair to say, then that a diesel turbo should have larger blades with less angle to better take advantage of higher temps instead of high mass flow? Then again, since the operating parameters of the diesel vary SO much, perhaps you'd just be trading one devil for another.
You are wise, imo, to bring up the idea that it's not just how much power you have available, but the nature of the power delivery-- how long you have to wait, and how long it will hold on before you either hit excessive EGT or some other limit.
In certain circumstances, I find that even my stock turbo is sometimes too slow in spoolup. Perhaps it's just that my current fueling setup can deliver a substantial change in fueling rate in very little time-- and therefore it might be unreasonable to think that that a turbo could spool fast enough to eliminate acceleration smoke.
This goes back to our earlier conversation about building twins with a secondary that's actually a little smaller than stock to improve spoolup and "fun", even if it's lower HP.
Maybe some "mini-twins" in the 450hp range? If you build them, please post the whole story!
Justin
I honestly completely ignored the different turbine designs for for different circumstances. Thanks for pointing that out and teaching us. Wouldn't it be fair to say, then that a diesel turbo should have larger blades with less angle to better take advantage of higher temps instead of high mass flow? Then again, since the operating parameters of the diesel vary SO much, perhaps you'd just be trading one devil for another.
You are wise, imo, to bring up the idea that it's not just how much power you have available, but the nature of the power delivery-- how long you have to wait, and how long it will hold on before you either hit excessive EGT or some other limit.
In certain circumstances, I find that even my stock turbo is sometimes too slow in spoolup. Perhaps it's just that my current fueling setup can deliver a substantial change in fueling rate in very little time-- and therefore it might be unreasonable to think that that a turbo could spool fast enough to eliminate acceleration smoke.
This goes back to our earlier conversation about building twins with a secondary that's actually a little smaller than stock to improve spoolup and "fun", even if it's lower HP.
Maybe some "mini-twins" in the 450hp range? If you build them, please post the whole story!
Justin
10-04-2007 | 04:49 AM
#95
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From: Austria Europe
Well over here if I'd do twins I'd be in big doodoo... There are a lot of laws concerning horsepower mods.. all of them inhibiting it. (We are taxed by hp..) So I have to keep the looks stock, and twins don't look stock. (This is also one main reason for the smarty for me. Half fuel setting with the injectors = no smoke and within the hp rating )
The stock turbo being to slow to spool is true much too often- especially in high altitudes with an auto with a tight TC.
I managed to get good results from doing a combo of those things:
A: Adjust valve lash to the tightest spec in the manual.
B: blueprint the exh. mainifold and the gaskets. (Let the enthalpy reach the turbine without undue restriction)
C: Ceramic coating the inside of the exh. mainifold and the tubine. (helps a lot with transient response- less heat soak of the metal parts until hot exh gas reaches the turbine.
D: Modified wastegate- opens further, bigger area and a hole through the divider- enables me to get away with a smaller housing, good prep for twins.
E: A small proportion of the housing isn't coated on the inside, there is a welded on ramp. In low flow situations a small "bubble of cooler gas forms behind the ramp, and reduces the housing size- in high flow the bubble is blown away. I do have positive manifold pressure at 1k rpm OD TC-Locked on flat ground. (And more boost than backpressure)
On the subject of twins- I am still pondering the idea of making them but composing them of a big single that will support 450-500 hp efficiently on it's own and a rather smallish turbo that could come from an engine with approx. 150hp so that the small one is there just to get the engine enough air to spool the big one. I don't think that the compressor side of the small one would pose too much of a restriction to hinder performance. And with that set I'd actually attach the big turbo directly to the manifold and install a diverter valve to the small turbo just before the big one- with the small ID pipe going to the little one and the "wastegate" of the little one being the diverter valve I'd shoot for a regulation like this- Standard cruising the diverter is going to the big one mainly- if going WOT one force from the pedal acting to push the diverter towards the small turbo and another force from a wastegate head pushing the diverter towards big turbo with increasing pressure differential across the small one. I think it would be tuning nightmare but if it works it should provide lightning response while keeping the efficiency of a big housing turbo for cruising.
On the angle and width/length of hte turbine blades there will always be a lot of compromises. The difference (while driving) for me is from approx 500F EGT @ 2-3psig boost@ 1200 rpm to 1300F EGT@30psig boost@ 3500 rpm. So mass flow etc does vary wildly on the diesel too, but on a gasser turbo we usually have almost fixed EGT in the operating range where the turbo boost is desired.
I think it's much more difficult to hit the sweet spot on a diesel due to extremely wide set of operating parameters.
(And the sweet spot will be different for each user-especially regarding auto-vs manual, axle ratio, tire size, speed limits etc. )
AlpineRAM
The stock turbo being to slow to spool is true much too often- especially in high altitudes with an auto with a tight TC.
I managed to get good results from doing a combo of those things:
A: Adjust valve lash to the tightest spec in the manual.
B: blueprint the exh. mainifold and the gaskets. (Let the enthalpy reach the turbine without undue restriction)
C: Ceramic coating the inside of the exh. mainifold and the tubine. (helps a lot with transient response- less heat soak of the metal parts until hot exh gas reaches the turbine.
D: Modified wastegate- opens further, bigger area and a hole through the divider- enables me to get away with a smaller housing, good prep for twins.
E: A small proportion of the housing isn't coated on the inside, there is a welded on ramp. In low flow situations a small "bubble of cooler gas forms behind the ramp, and reduces the housing size- in high flow the bubble is blown away. I do have positive manifold pressure at 1k rpm OD TC-Locked on flat ground. (And more boost than backpressure)
On the subject of twins- I am still pondering the idea of making them but composing them of a big single that will support 450-500 hp efficiently on it's own and a rather smallish turbo that could come from an engine with approx. 150hp so that the small one is there just to get the engine enough air to spool the big one. I don't think that the compressor side of the small one would pose too much of a restriction to hinder performance. And with that set I'd actually attach the big turbo directly to the manifold and install a diverter valve to the small turbo just before the big one- with the small ID pipe going to the little one and the "wastegate" of the little one being the diverter valve I'd shoot for a regulation like this- Standard cruising the diverter is going to the big one mainly- if going WOT one force from the pedal acting to push the diverter towards the small turbo and another force from a wastegate head pushing the diverter towards big turbo with increasing pressure differential across the small one. I think it would be tuning nightmare but if it works it should provide lightning response while keeping the efficiency of a big housing turbo for cruising.
On the angle and width/length of hte turbine blades there will always be a lot of compromises. The difference (while driving) for me is from approx 500F EGT @ 2-3psig boost@ 1200 rpm to 1300F EGT@30psig boost@ 3500 rpm. So mass flow etc does vary wildly on the diesel too, but on a gasser turbo we usually have almost fixed EGT in the operating range where the turbo boost is desired.
I think it's much more difficult to hit the sweet spot on a diesel due to extremely wide set of operating parameters.
(And the sweet spot will be different for each user-especially regarding auto-vs manual, axle ratio, tire size, speed limits etc. )
AlpineRAM
10-04-2007 | 07:52 AM
#96
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From: Rural Hall, NC
A small proportion of the housing isn't coated on the inside, there is a welded on ramp. In low flow situations a small "bubble of cooler gas forms behind the ramp, and reduces the housing size- in high flow the bubble is blown away. I do have positive manifold pressure at 1k rpm OD TC-Locked on flat ground. (And more boost than backpressure)
10-04-2007 | 10:24 AM
#97
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Alpine Ram has nailed quite a few things in his intelligently written post.
Not the least of which is coating the inside and outside of the exhaust manifold and insulating it well. I have been beating this to death for years on this board and there is no question it is one of the best things you can do to help spoolup. It would be criminal to purchase a nice new ATS manifold and then install it without coating in inside and out at a minimum, and for best results, insulating the outside when you are done.
What would be even better is to build a thin walled tubular exhaust manifold, and have it coated and insulated. This would greatly reduce the thermal mass and would minimize the drop in exhaust temperature accross the manifold during a transient.
And I too have been a proponet for a ludicrous quick spooling SMALL twin setup for quite a while. I just have to get through my backlog of other projects at home and build em !!!
Kp
Not the least of which is coating the inside and outside of the exhaust manifold and insulating it well. I have been beating this to death for years on this board and there is no question it is one of the best things you can do to help spoolup. It would be criminal to purchase a nice new ATS manifold and then install it without coating in inside and out at a minimum, and for best results, insulating the outside when you are done.
What would be even better is to build a thin walled tubular exhaust manifold, and have it coated and insulated. This would greatly reduce the thermal mass and would minimize the drop in exhaust temperature accross the manifold during a transient.
And I too have been a proponet for a ludicrous quick spooling SMALL twin setup for quite a while. I just have to get through my backlog of other projects at home and build em !!!
Kp
10-04-2007 | 12:56 PM
#98
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From: Cummins Technical Center, IN
My ATS manifold will go to SWAIN TECH for the full coating treatment before it ever touches the engine on my truck.
As will the turbine housing for whatever turbo I end up getting (right now BB Garrett stg 2 is choice #1). Based on my reading, I have goood reason to think this particular Garrett will spool even faster than my stocker (certainly no worse), while still flowing a little more at higher PRs.
A person could build a lightning fast spooling twins setup using a small GT28-sized top charger and something like a Silver Bullet or GT4294 for a primary. It would need a huge w/g though because drive pressures with than tiny turbo could get pretty bad.
Get on those projects, my friend! We want to see your brainchild in action.
Alpine, I was unaware of the legalities of modding your truck, so I suspect that you have to be even more creative in your HP solutions...
Justin
As will the turbine housing for whatever turbo I end up getting (right now BB Garrett stg 2 is choice #1). Based on my reading, I have goood reason to think this particular Garrett will spool even faster than my stocker (certainly no worse), while still flowing a little more at higher PRs.
A person could build a lightning fast spooling twins setup using a small GT28-sized top charger and something like a Silver Bullet or GT4294 for a primary. It would need a huge w/g though because drive pressures with than tiny turbo could get pretty bad.
Get on those projects, my friend! We want to see your brainchild in action.
Alpine, I was unaware of the legalities of modding your truck, so I suspect that you have to be even more creative in your HP solutions...
Justin
10-04-2007 | 02:04 PM
#99
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From: Warsaw, In
I will be doing the same thing to my turbine housing and manifold as soon as I decide on which turbo to go with. Swaintech's ceramic coating is one of the best.
Although I would be concerned about coating the inside of the manifold and housing due to it chipping off and getting into the turbine. They mention this on there website. They say they cant get it prepped well enough to ensure that it sticks. It needs to be sandblasted to get it to stick right and well thats pretty hard to do inside of a manifold.
Although I would be concerned about coating the inside of the manifold and housing due to it chipping off and getting into the turbine. They mention this on there website. They say they cant get it prepped well enough to ensure that it sticks. It needs to be sandblasted to get it to stick right and well thats pretty hard to do inside of a manifold.
10-04-2007 | 02:39 PM
#101
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From: Cummins Technical Center, IN
I will be doing the same thing to my turbine housing and manifold as soon as I decide on which turbo to go with. Swaintech's ceramic coating is one of the best.
Although I would be concerned about coating the inside of the manifold and housing due to it chipping off and getting into the turbine. They mention this on there website. They say they cant get it prepped well enough to ensure that it sticks. It needs to be sandblasted to get it to stick right and well thats pretty hard to do inside of a manifold.
Although I would be concerned about coating the inside of the manifold and housing due to it chipping off and getting into the turbine. They mention this on there website. They say they cant get it prepped well enough to ensure that it sticks. It needs to be sandblasted to get it to stick right and well thats pretty hard to do inside of a manifold.
You could get the manifold extrude-honed to prep the surface-- have them use a really coarse media and it will be good to go.
jh
10-04-2007 | 05:46 PM
#102
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That would be one expensive manifold by the time to got done with it.
ExtrudeHone is def not cheap. It would clean it up pretty good after any porting work though.
10-04-2007 | 09:00 PM
#103
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You just need to blast it with an extremely large industrial sand blaster. We are talking 3/4 to 1" line. Like the type they use when they re-paint a bridge.... or clean the turbine blades at a power station.............
.
Trust me, you put a 1" sand blasting nozzle with coarse media and stick it in each port and let it rip for about 2 minutes, and every portion of the port is blasted !!!
Kp
. Trust me, you put a 1" sand blasting nozzle with coarse media and stick it in each port and let it rip for about 2 minutes, and every portion of the port is blasted !!!
Kp
10-04-2007 | 10:57 PM
#104
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What type of coating does Swain Tech offer? And does anyone know about what it would cost? I am going to buy an ATS or HTT manifold later on and when I do I will port it out and then blend those areas into the actual manifold and possibly hog the I.D. out a smidge...
10-04-2007 | 11:24 PM
#105
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