Upper torque limit for standard block
10-14-2004, 12:38 PM
#20
Addict
Rennlist Member
Rennlist Member
Join Date: May 2002
Location: Phoenix, AZ - NJ Runaway
Posts: 3,649
Likes: 0
Received 0 Likes
on
0 Posts
Yeah, he needed that kit like he needed a hole in his head. His mustang puts down over 600 RWHP. At least he's moving in the right direction now......
10-14-2004, 06:56 PM
#21
Rennlist Member
Laust,
I hate to see a fellow enthusiasts' motor go belly up.
That's why,when you orginally posted your goals, I thought that you're going against all engineering principals. I mentioned to you that you should bring the water in as vapor; not port injection (unless it's very, very little). Also, huge backpressure can not be neutralized with WI and hot exhaust cannot excape the cylinders. You didn't have detonnation (way to much water); you probably had some sort of thermal shock.
You had something set in your mind, and hell or high water (pun intended) could not steer you away from a blunder.
I would have thought, though, that the only downside would have been much less power than you expected. This obviously sucks. I guess we really don't know for sure what caused this. I just know trying to make alot of power with a small turbo is like trying to build a train bridge with matchsticks. No secret recipe (water injection) is going to make it work.
Sometimes, there are some good points made by others on this forum and sometimes this can put a different perspective on things that you've read or heard from somebody who's suppossedly "in the know".
Hopefully you haven't lost interest in the 951's potential.
I hate to see a fellow enthusiasts' motor go belly up.
That's why,when you orginally posted your goals, I thought that you're going against all engineering principals. I mentioned to you that you should bring the water in as vapor; not port injection (unless it's very, very little). Also, huge backpressure can not be neutralized with WI and hot exhaust cannot excape the cylinders. You didn't have detonnation (way to much water); you probably had some sort of thermal shock.
You had something set in your mind, and hell or high water (pun intended) could not steer you away from a blunder.
I would have thought, though, that the only downside would have been much less power than you expected. This obviously sucks. I guess we really don't know for sure what caused this. I just know trying to make alot of power with a small turbo is like trying to build a train bridge with matchsticks. No secret recipe (water injection) is going to make it work.
Sometimes, there are some good points made by others on this forum and sometimes this can put a different perspective on things that you've read or heard from somebody who's suppossedly "in the know".
Hopefully you haven't lost interest in the 951's potential.
10-15-2004, 12:12 AM
#23
Drifting
Atomize the water before the throttle plate. The vapor will be better distributed and more effective. Port injecting the water is VERY risky. Like he said, it needs to be a very small amount or really bad things happen. Pictures above look like what I have seen.
I don't know the whole story on this "project" but it seems to me the only way to make it grenade faster would be to try and spin it to 8k rpm. What a waste.
I don't know the whole story on this "project" but it seems to me the only way to make it grenade faster would be to try and spin it to 8k rpm. What a waste.
Last edited by Chris Prack; 10-15-2004 at 10:00 PM.
10-15-2004, 02:17 PM
#24
Racer
Join Date: Nov 2003
Location: Arizona
Posts: 358
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by Jeremy Himsel
Yeah, he needed that kit like he needed a hole in his head. His mustang puts down over 600 RWHP. At least he's moving in the right direction now......
I'M NOT WORTHY!
10-15-2004, 04:23 PM
#25
Burning Brakes
Join Date: Jul 2004
Location: Official Jack off extinguisher
Posts: 1,173
Likes: 0
Received 1 Like
on
1 Post
You have to look at the actual compression ratio 25 psi boost will give you combined that with a turbo way out of it's efficient range and bandaid port water injection it is no surprise something had to give, first the headgasket and now the block.
If I remember correctly the Ford powerstroke diesel has a 16:1 cr, guess what you have...............
If I remember correctly the Ford powerstroke diesel has a 16:1 cr, guess what you have...............
10-16-2004, 07:59 PM
#26
Pro
Join Date: Sep 2003
Location: Boden, Sweden
Posts: 603
Likes: 0
Received 0 Likes
on
0 Posts
Laust, sorry to hear about your engine. Makes me a little scared to take the head of mine that's sitting in the garage with a blown HG (bad WG hose).
I understand that the challange for you is to get as much horsepower as possible from your K26. The thing is that there is a limit that you can't go beyond, when the flow gets too high for your compressor, the compressor wheel rpm increases to very high levels and the tips of the blades reaches supersonic speeds. At that point the compressor has more or less reached it's flow limit. If you try to go beyond this, you will only heat the air more and spin your turbo to insane rpm's. In the compressor map you can see how the rpm lines gets closer to each other when you pass the efficiency peak, when they get vertical you are very closed to the pump limit.
It's not unlikely that you end up loosing power due the to the low air density entering the cylinders and the fact that the water needed to get the temperature down replaces air in the cylinders and slows down combustion speed.
Although I don't agree that you are heading in the right direction on this one, I do think that it's a good thing that someone dares to do unconventional things too push the limits.
Tomas
I understand that the challange for you is to get as much horsepower as possible from your K26. The thing is that there is a limit that you can't go beyond, when the flow gets too high for your compressor, the compressor wheel rpm increases to very high levels and the tips of the blades reaches supersonic speeds. At that point the compressor has more or less reached it's flow limit. If you try to go beyond this, you will only heat the air more and spin your turbo to insane rpm's. In the compressor map you can see how the rpm lines gets closer to each other when you pass the efficiency peak, when they get vertical you are very closed to the pump limit.
It's not unlikely that you end up loosing power due the to the low air density entering the cylinders and the fact that the water needed to get the temperature down replaces air in the cylinders and slows down combustion speed.
Although I don't agree that you are heading in the right direction on this one, I do think that it's a good thing that someone dares to do unconventional things too push the limits.
Tomas
Last edited by Tomas L; 10-16-2004 at 08:41 PM. Reason: Inserted compressor map
10-21-2004, 02:27 AM
#27
Addict
Rennlist Member
Rennlist Member
Thread Starter
“Got Me a Phosha”,
Thanks for the picture, very valuable and interestingly enough the crack is at the same place as mine.
And just stay at the same level of analytical sophistication as you present, here is the root cause for the “disaster”: I bought a 951.
“Turbo Tommy”,
I am going against common practice, but not sound engineering principles, big difference.
I also very much noted your aversion toward the direction I was (and am) taking as well as the slightly condescending tone in your posts on the subject and have to say, that your qualitative arguments are lightweight and conclusions based on opinions clothed as facts. I think you could benefit by the following:
1) Please read a few SAE papers on this and closely related subjects, for example:
a) “Prediction of Nox Reduction Rate Due to Port Water Injection in a Di Diesel Engine ”
b) “Impingement Spray System With Direct Water Injection for Premixed Lean Diesel Combustion Control ”
c) “Fuel Consumption Improvement and Operation Range Expansion in Hcci By Direct Water Injection ”
d) “Significant Nox Reductions With Direct-Water Injection Into the Sub-Chamber of An Idi Diesel Engine ”
e) “Total Cooling of Piston Engines By Direct Water Injection ”
f) “Total Cooling of Piston Engines By Direct Water Injection ”
2) Please explain your understanding of “thermal shock” and its detrimental effects. Also, please outline the differences between quenching (hardening of some metals) and thermal shock.
3) Please explain why almost all manufacturers now use port fuel injection (as opposed to the cheaper throttle body injection) and draw parallels to water injection.
4) Please calculate the approximate per cylinder cooling effect of fuel at 350HP and compare it to the amount of water I used (I know you don’t know what that is and yet you form opinions), but just calculate the typical amount of water used.
5) Please also compare the (typical) amount of water used for water injection to a) the amount ingested at close to 100 % humidity and b) the amount of water produced by the combustion process and state your reference(s) on that information.
6) And lastly: What do you estimate the upper reliable HP and TQ limits to be with the K26-6 and port water injection?
One thing you are right about is that we may never know what exactly caused the crack or in which proportion the different mechanisms contributed to the destruction.
Another part of my philosophy is that if the engine is so stressed, that a brief period of detonation destroys it, then the safety factor is inadequate. Since I consider this to be the probable reason, I am designing a strengthening and fixing brace for the cylinders, with potential for commercialization.
Only the weak buckle under adversity.
“pole position”,
Why guess when the effective CR can be calculated?
I’ll just wait for your calculations (before seriously responding to your post).
Thomas,
You seem to imply that the sound velocity is an upper limit for the impeller speed. However I have heard that some airplanes fly at Marc 3 and have specific knowledge, that the turbine tip speed in some of those engines are above the speed of sound.
The surging (upper flow limit), as I understand it, is due to the fact that the inlet of the compressor has to accelerate so much air that it actually pulls vacuum, resulting in increasing speed of the shaft, due to low resistance. Moments late the air reaches the impeller, slowing it down again and setting up a possible oscillation of the shaft speed.
You have to be careful throwing in a compressor chart as a gospel for “the truth”. The fact is that the K26 compressor came with in a few variations. I have specific knowledge that the compressor side is not the same for the K26-6 and K26-8.
A very important factor to consider is under which boundary conditions were the measurements taken, i.e. Was it an open inlet tract? Was the inlet preceded with a Laval nozzle? Or was the air sped up with a tract as with the J-boot we have? I suspect the first condition, but no documentation to that effect.
Of some, but minor importance, is also the lack of information on the ambient humidity.
Jeremy,
Yes that is my SOP. During the development of the chips, I used 89 octane pump gas for the specific purpose of having an extra safety margin when going on the track with 91 octane. Whenever I heard traces of pinging or noted less than optimum AFR at WOT, Danno revised the chips according to my input. I don’t have the resulting WOT timing numbers, but understand that it is very close the 18 psi non-waster values.
Laust
Thanks for the picture, very valuable and interestingly enough the crack is at the same place as mine.
And just stay at the same level of analytical sophistication as you present, here is the root cause for the “disaster”: I bought a 951.
“Turbo Tommy”,
I am going against common practice, but not sound engineering principles, big difference.
I also very much noted your aversion toward the direction I was (and am) taking as well as the slightly condescending tone in your posts on the subject and have to say, that your qualitative arguments are lightweight and conclusions based on opinions clothed as facts. I think you could benefit by the following:
1) Please read a few SAE papers on this and closely related subjects, for example:
a) “Prediction of Nox Reduction Rate Due to Port Water Injection in a Di Diesel Engine ”
b) “Impingement Spray System With Direct Water Injection for Premixed Lean Diesel Combustion Control ”
c) “Fuel Consumption Improvement and Operation Range Expansion in Hcci By Direct Water Injection ”
d) “Significant Nox Reductions With Direct-Water Injection Into the Sub-Chamber of An Idi Diesel Engine ”
e) “Total Cooling of Piston Engines By Direct Water Injection ”
f) “Total Cooling of Piston Engines By Direct Water Injection ”
2) Please explain your understanding of “thermal shock” and its detrimental effects. Also, please outline the differences between quenching (hardening of some metals) and thermal shock.
3) Please explain why almost all manufacturers now use port fuel injection (as opposed to the cheaper throttle body injection) and draw parallels to water injection.
4) Please calculate the approximate per cylinder cooling effect of fuel at 350HP and compare it to the amount of water I used (I know you don’t know what that is and yet you form opinions), but just calculate the typical amount of water used.
5) Please also compare the (typical) amount of water used for water injection to a) the amount ingested at close to 100 % humidity and b) the amount of water produced by the combustion process and state your reference(s) on that information.
6) And lastly: What do you estimate the upper reliable HP and TQ limits to be with the K26-6 and port water injection?
One thing you are right about is that we may never know what exactly caused the crack or in which proportion the different mechanisms contributed to the destruction.
Another part of my philosophy is that if the engine is so stressed, that a brief period of detonation destroys it, then the safety factor is inadequate. Since I consider this to be the probable reason, I am designing a strengthening and fixing brace for the cylinders, with potential for commercialization.
Only the weak buckle under adversity.
“pole position”,
Why guess when the effective CR can be calculated?
I’ll just wait for your calculations (before seriously responding to your post).
Thomas,
You seem to imply that the sound velocity is an upper limit for the impeller speed. However I have heard that some airplanes fly at Marc 3 and have specific knowledge, that the turbine tip speed in some of those engines are above the speed of sound.
The surging (upper flow limit), as I understand it, is due to the fact that the inlet of the compressor has to accelerate so much air that it actually pulls vacuum, resulting in increasing speed of the shaft, due to low resistance. Moments late the air reaches the impeller, slowing it down again and setting up a possible oscillation of the shaft speed.
You have to be careful throwing in a compressor chart as a gospel for “the truth”. The fact is that the K26 compressor came with in a few variations. I have specific knowledge that the compressor side is not the same for the K26-6 and K26-8.
A very important factor to consider is under which boundary conditions were the measurements taken, i.e. Was it an open inlet tract? Was the inlet preceded with a Laval nozzle? Or was the air sped up with a tract as with the J-boot we have? I suspect the first condition, but no documentation to that effect.
Of some, but minor importance, is also the lack of information on the ambient humidity.
Jeremy,
Yes that is my SOP. During the development of the chips, I used 89 octane pump gas for the specific purpose of having an extra safety margin when going on the track with 91 octane. Whenever I heard traces of pinging or noted less than optimum AFR at WOT, Danno revised the chips according to my input. I don’t have the resulting WOT timing numbers, but understand that it is very close the 18 psi non-waster values.
Laust
10-21-2004, 06:37 AM
#28
Race Director
When talking with engineering concepts, the determination of validity has to rest on the quantitative numbers. One such number is the 1500lb of lateral force on the cylinder walls due to the angle of the con-rod on the power-stroke. Let's see some other numbers to support or refute the ideas presents.
Some others have had blocks that cracked suddenly, Mumzer at Laguna Seca and Andy Alberts in NY. From the info they presented, it appears to have been fatigue failure as well (stress over time). The fact that it was the #4 cylinder appears to match the most prevalent cylinder where headgasket failures occur, so I wonder if there's a correlation here.
Here's something I haven't seen here yet, and that's the effects of knock/detonation on the piston, head and valves. I've blown up plenty of V4 14,000rpm motorcycle engines, and the ones that failed due to lean mixture and detonation (one from the mistaken use of 100LL) all had even damage to all the parts, the pistons, the cylinder walls, the head and valves. That's because the intense confrontation of multiple flame-fronts results in high-pressure waves that spread out in all directions. The tops of the pistons were melted, some of them all the way through. The head had wavey spots showing melting alloy, the rings were shattered, the cylinders had pock-marks (larger versions of the pits you see on the headgasket's compression-ring). On Laust's engine, the only damage was the cylinder, and it was from fatigue, not a sudden traumatic event.
I think this experiment may yield some useful additional data for all of us.
Some others have had blocks that cracked suddenly, Mumzer at Laguna Seca and Andy Alberts in NY. From the info they presented, it appears to have been fatigue failure as well (stress over time). The fact that it was the #4 cylinder appears to match the most prevalent cylinder where headgasket failures occur, so I wonder if there's a correlation here.
Here's something I haven't seen here yet, and that's the effects of knock/detonation on the piston, head and valves. I've blown up plenty of V4 14,000rpm motorcycle engines, and the ones that failed due to lean mixture and detonation (one from the mistaken use of 100LL) all had even damage to all the parts, the pistons, the cylinder walls, the head and valves. That's because the intense confrontation of multiple flame-fronts results in high-pressure waves that spread out in all directions. The tops of the pistons were melted, some of them all the way through. The head had wavey spots showing melting alloy, the rings were shattered, the cylinders had pock-marks (larger versions of the pits you see on the headgasket's compression-ring). On Laust's engine, the only damage was the cylinder, and it was from fatigue, not a sudden traumatic event.
I think this experiment may yield some useful additional data for all of us.
10-21-2004, 04:01 PM
#29
Pro
Join Date: Sep 2003
Location: Boden, Sweden
Posts: 603
Likes: 0
Received 0 Likes
on
0 Posts
Laust,
The reason that I posted the compressor chart was to better illustrate how the shaft rpm lines get vertical and very close together at high flow. I didn't say that this was the chart for your compressor, I could just as well used a Garrett chart. The point was that there is a limit to what a compressor can flow. This may not be a "hard" limit, it may be possible to get a little more flow under the right conditions but still you will loose efficiency, you'll risk blowing up your turbine and compressor wheels and the power needed to drive the compressor will cause huge exhaust backpressure.
I have never heard that a compressor will go into surge at high flow, only at low flow/high pressure?
As I understand it you can never pull air faster than the speed of sound (at the actual conditions), it is however possible to push it at faster speed. Are you sure that the pressure in that jet engine isn't so high that the speed of sound at those conditions is not reached?
Tomas
The reason that I posted the compressor chart was to better illustrate how the shaft rpm lines get vertical and very close together at high flow. I didn't say that this was the chart for your compressor, I could just as well used a Garrett chart. The point was that there is a limit to what a compressor can flow. This may not be a "hard" limit, it may be possible to get a little more flow under the right conditions but still you will loose efficiency, you'll risk blowing up your turbine and compressor wheels and the power needed to drive the compressor will cause huge exhaust backpressure.
I have never heard that a compressor will go into surge at high flow, only at low flow/high pressure?
As I understand it you can never pull air faster than the speed of sound (at the actual conditions), it is however possible to push it at faster speed. Are you sure that the pressure in that jet engine isn't so high that the speed of sound at those conditions is not reached?
Tomas
10-22-2004, 01:22 PM
#30
Three Wheelin'
More on topic, here is an old post by Konstantin, explaining how he got flow estimates for his intake manifold runners.
"Hello
first of all check this site to see what I question: <a href="http://www.lindseyracing.com/944eng21.htm" target="_blank">http://www.lindseyracing.com/944eng21.htm</a>
now what and how I tested
I put a big blower in front of the intake manifold. With a very accurate industrial thermometer I messured the temp on each intake just at the same place (where the injectors fits)
The difference was the same for all. number one had the hottest temp. #2 had 2% cooler temp, #3 had another 3% cooler temp and # 4 had another 2% cooler temp. I was thinking that the higher the airflow the cooler the air temp should be. so Iincreased the air velocity by increasing the fan speed and this was the case. the temp was lower on each intake and the difference was still 25 betwenn the intakes. #4 was the coolest.
After that I used a piece of paper. put it at the end of the intake manifold and messured the deflection on the paper.
On #1 intake the deflection was almost minmal. The paper barely move. on #4 the deflection was VERY noticable.
After that I used anothe rpiece of paper and mesure the height where the apper started to fly.
On#1 intake startet at 2cm above the inteke end. on# 4 at 10 cm above the intake end.
That means the air coming out of the intake had so much power that it could move teh paper at 10 cm above the intake end.
On#1 intake it was so less pressure that I had to put the paper so close (2cm) to teh inatke to make it move.
I can not provide any numbers as I do not have something that messure the air flow or speed accurate but for me is clearly that with a simple test #4 flows more and #1 flows the least. you can even say this by puting yor hand at the end of the intake manifold when you put a blower in front of the throttle body.
#4 has the more air delivering!!!
maybe someone else can make a better test and come up with some numbers.
I repeted the test with water and the result was the same. the most water and the intake that the water came up as firts out of teh intake manifold was #4.
I think #4 is the one with the most air.
BUT!!!!!!
if you consider that #4 is hotter when it is instaled in the car, that means that you have less oxygen in the same volume of air. # 4 flows more air but the air is hotter, so the real oxygen is not as high as we would think. the higher air flow is "somehow" compensated by the hotter air temp in each the intake manifold runer.
so it should be about the same oxygen delivered even if #4 flows more than the other.
any thoughts?
Konstantin"
This would explain how detonation could cause the failure in #4, caused by detonation. Number 4 flows more air, but usually it would be hotter air as well, to cancel out the more flow. But with Laust's water injection, he cooled the air so much that it began to run lean, and it detonated. I am going to have my manifold flow matched before I do anything else on my project.
Good point about how it doesnt look like detonation danno, but what else? Some kind of miniature hydrolock due to a WI malfunction?
"Hello
first of all check this site to see what I question: <a href="http://www.lindseyracing.com/944eng21.htm" target="_blank">http://www.lindseyracing.com/944eng21.htm</a>
now what and how I tested
I put a big blower in front of the intake manifold. With a very accurate industrial thermometer I messured the temp on each intake just at the same place (where the injectors fits)
The difference was the same for all. number one had the hottest temp. #2 had 2% cooler temp, #3 had another 3% cooler temp and # 4 had another 2% cooler temp. I was thinking that the higher the airflow the cooler the air temp should be. so Iincreased the air velocity by increasing the fan speed and this was the case. the temp was lower on each intake and the difference was still 25 betwenn the intakes. #4 was the coolest.
After that I used a piece of paper. put it at the end of the intake manifold and messured the deflection on the paper.
On #1 intake the deflection was almost minmal. The paper barely move. on #4 the deflection was VERY noticable.
After that I used anothe rpiece of paper and mesure the height where the apper started to fly.
On#1 intake startet at 2cm above the inteke end. on# 4 at 10 cm above the intake end.
That means the air coming out of the intake had so much power that it could move teh paper at 10 cm above the intake end.
On#1 intake it was so less pressure that I had to put the paper so close (2cm) to teh inatke to make it move.
I can not provide any numbers as I do not have something that messure the air flow or speed accurate but for me is clearly that with a simple test #4 flows more and #1 flows the least. you can even say this by puting yor hand at the end of the intake manifold when you put a blower in front of the throttle body.
#4 has the more air delivering!!!
maybe someone else can make a better test and come up with some numbers.
I repeted the test with water and the result was the same. the most water and the intake that the water came up as firts out of teh intake manifold was #4.
I think #4 is the one with the most air.
BUT!!!!!!
if you consider that #4 is hotter when it is instaled in the car, that means that you have less oxygen in the same volume of air. # 4 flows more air but the air is hotter, so the real oxygen is not as high as we would think. the higher air flow is "somehow" compensated by the hotter air temp in each the intake manifold runer.
so it should be about the same oxygen delivered even if #4 flows more than the other.
any thoughts?
Konstantin"
This would explain how detonation could cause the failure in #4, caused by detonation. Number 4 flows more air, but usually it would be hotter air as well, to cancel out the more flow. But with Laust's water injection, he cooled the air so much that it began to run lean, and it detonated. I am going to have my manifold flow matched before I do anything else on my project.
Good point about how it doesnt look like detonation danno, but what else? Some kind of miniature hydrolock due to a WI malfunction?