Turbine melting on gt42
08-24-05, 06:19 AM
#26
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Originally Posted by RETed
I thought water injection is supposed to drop EGT's?
When did Max start messing with water injection?
To claim "shoot for 970C" is just plain ridiculous.
Come on Max, you figure it out why.
EGT gauges don't always read the same.
There's a fine art to tuning with an EGT gauge, and telling anyone to shoot for a certain temp is very wrong.
I had to tune a GT35R that would like 900C EGT's for best power.
At the same time, I tuned an H-trim hybrid that was barely getting over 700C.
Both motors were similarly ported.
Both were using the same brand and type of EGT gauge.
-Ted
When did Max start messing with water injection?
To claim "shoot for 970C" is just plain ridiculous.
Come on Max, you figure it out why.
EGT gauges don't always read the same.
There's a fine art to tuning with an EGT gauge, and telling anyone to shoot for a certain temp is very wrong.
I had to tune a GT35R that would like 900C EGT's for best power.
At the same time, I tuned an H-trim hybrid that was barely getting over 700C.
Both motors were similarly ported.
Both were using the same brand and type of EGT gauge.
-Ted
Something was wrong with the one of the guages, probably the one reading just over 700 c, you should be able to figure that one out TED....Putting all your tuning eggs in one basket is ridiculous, ... I have observed stock twins tuned to 360 rwhp the final egt was just shy of 950, then a 619 rwhp T51 tuned, final egt was in the 960's, you arguing discrepencies among numbers from guages you cant trust, not the numbers themselves...Try using calibrated guages next time...
Anyone with any experience knows that pretty much every mazda rotary no matter what the configuration has puts out egt's in the 1600-2000 F range, so if I were tuning a motor, that was reading 700 under boost at WOT , I would suspect something, like reversed polarity on the egt probe or a bad Guage..
Most of the tuners in Japan will not use the cars egt guage for tuning, but their own tried and tested egt they know works for that very reason..Its their for reference purposes to the driver, if the peak warn kept going a little higher and higher every time, it would point to something being wrong..I use an fast acting industrial guage meter with high temp probe good to 1400 C in my car..
Here is a translated text that appears in every tuning article in the Japanese magazines, and the same numbers were reiterated to me by tuners such as Revolution, KKM etc etc..
"The upper limit being instantaneous as a standard, 1100 c being usual, 970 c is usual best setting. 850 c compared to being low, power goes down."...I guess we know why the RE is so much more successful there, than it is here...
"
Last edited by Maxthe7man; 08-24-05 at 06:33 AM.
08-24-05, 08:26 AM
#27
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Since when thermocouples were "different"?
If you knew how thermocouples worked, I find it hard to believe that switching the "polarities" would induce what you described.
Nevermind, Google search works wonders...
http://yarchive.net/electr/thermocouples.html
http://www.branom.com/literature/thermo.html
I think it'll be obvious if it were wired in reverse.
If it's going to spit out a negative signal, the gauge should not even go into the "positive" side of the scale.
As for running calibrated EGT systems...you're right, I just run anything out of Japan.
Shame on me for assuming GReddy, HKS, A'PEXi would all not be calibrated.
-Ted
If you knew how thermocouples worked, I find it hard to believe that switching the "polarities" would induce what you described.
Nevermind, Google search works wonders...
http://yarchive.net/electr/thermocouples.html
http://www.branom.com/literature/thermo.html
I think it'll be obvious if it were wired in reverse.
If it's going to spit out a negative signal, the gauge should not even go into the "positive" side of the scale.
As for running calibrated EGT systems...you're right, I just run anything out of Japan.
Shame on me for assuming GReddy, HKS, A'PEXi would all not be calibrated.
-Ted
Last edited by RETed; 08-24-05 at 08:51 AM.
08-24-05, 02:52 PM
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My turbo dealer told me the GT42/51R has an inconel turbine wheel,and is good for sustained 950c,and occasional 1053c. The turbo is on my 12A,which has done 700 miles since I last looked at the turbine,and it is still melting.EGT,I have seen 925c only a couple of times.Cruising 4-5000rpm is 800c.Max boost has been 1.2 bar.
Looking at the turbine housing and comparing it with a gt35r one,the gt35r one looks like it will flow more even though the gt42/51r one is huge.
I want a proper turbo,considering a t51r hks turbo.
Looking at the turbine housing and comparing it with a gt35r one,the gt35r one looks like it will flow more even though the gt42/51r one is huge.
I want a proper turbo,considering a t51r hks turbo.
08-24-05, 03:10 PM
#29
Short burst, hardly most of my boosting is long duration highway pulls, I live in the middle of nowhere, a short burst for me is 25 miles.. IF you cant tune to a proper egt without raising your oil/water temps into danger range, you have other problems, like your cooling setup.. Through a 4th gear pull I only raise 2-3 deg on coolant and 10 deg on oil pre cooler...Cooling stability is half the key to running high boost on pump gas...If your tuner recommends 700c, he is no rotary tuner, he's just runing the motor in a overly cautious detuned inefficient state since he has no idea of the engines true bounds...Street car or Time attack, it doesnt matter, tuning the engine for high output and reliable power is important for both, it wouldnt be much of race if the engine blows on the first straightaway would it..
Okay, this is why I would not advocate tuning for 970 C on a street car. The short bursts with long cool downs of highway pulls WILL NOT put your engine under full thermal loading.
I did the same thing. I tried consecutive zero to redline 5th gear pulls, roll on to redline pulls and finally loading the engine with the brakes and pulling to redline (don't do this its stupid when you have enough power to flatspot your front tires and burn your rears off in 5th). Intake temps were only peaking ~20 C over ambient and coolant temps barely off the 82 C thermostat opening.
Do the same 25 miles on your favorite tortuous mountain road or short circuit and you WILL see much higher thermal loading in all the fluids (intake, oil, coolant, exhaust). I would start driving hard, slow down enough to hit the data log key and continue until I ran out of log. Start with short runs, you may be amazed how quickly your 970 C freeway tune can turn into a 1100 C mistake.
700 c is way to cold, when I first tuned I was seeing that egt with the wideband reading 10.2:1 with 4x1600. The truth it was i t was in the 9's and the lowest reading of the wideband was 10.2, it was running 700 c because it was pig rich, and thats the only reason it was running at that temp..
Too cold for what? If I can do 400HP at ~700 C and only 420HP at 970C I would choose the 400HP. My menatlity is a street car has to be tuned like an endurance race car, not a time attack sprint car. That might be a difference in driving, I like to push a set-up.
970 is the optimum, if you tune to that egt you will most likely find your maximum power there, tuning with egt and g-tech I found this to be so... If your tune is right and your maps smooth and not knotchy jumping all over the places with the air fules, you will find your egt will find its peak, and its tunable to a given egt..
No, that is where YOUR set-up starts losing power due to EGT to intake carry over from overlap when spooling and the trailing plug orfice or too high oil/ coolant temps. Think about that.... You are closer to the edge than you may think in my opinion.
Give it more EGT holding all other factors the same an you will get more HP.
If the Hurleys cant handle 970, they simply dont belong in a rotary period...
If stock seals can only handle 1100 C they don't belong in a performance rotary perion... Ceramics can handle so much more. You understand what I mean?
I have read Mazda sponsored engine builder Darly Drummond talk about how stock apex seals lose hp in one season due to damage on the low performance NA Mazda star spec engines and ceramics hold up great and hold the blueprinted HP.
The point of the side seal being in at zero, if you cant fit a feeler guage in there its msot likely sprung between the two corner seals... I have met RE's engine builder, and he does not "zero clearnace", Zero and .0015 are not the same..And gently breaking it In? whats with that, if its bowed at all it will have a broken side seal from the first day its started...What are you going to do? Keep pulling the motor apart to see if its self clearanced itself?... Start at .0015 and work from there, not zero..
You know you can fit a feeler gauge in there if a sideseal that is so long it binds. 2 corner seals to **** in the bore, the depth of the sidseal slot to misalign the sideseal at each end and the sideseal side clearance to bow the seal in- it adds up to more than .0015 and that is why the feeler gauge isn't the best way to clearance them.
You asked him what to set the sideseals at and he told you .0015? Under Mazda spec, thats telling. Now watch him DO it. Is there a feeler gauge? If someone at my work tells me they are chipping, wearing drill bits fast I would hand them a drill speed chart instead of taking the time to lecture on watching the waste material come off the work and what to look for. You can't summ up "craftsmaship" in a measurement, so you give the quick answer.
You break it in with low thermal and mechanical loading so you don't stress the sideseal before it seats (wears) into the corner seal. Seating into the cornerseal gives you a better gas seal than a straight gap. If you like to break it in with a burnout like Ito run the .007 gap he recommends. His customers would rather be out driving hard right away instead of obscessing about every last bit of sealing from a proper break-in/build. Where do you stand?
Obviously, or you would know the maximum recommended egt of stock seals is 1100 C and you wouldnt be arguing against 970c....
??? I am not saying rebuild your engine if its peaked at 970 C because you have compromised your seals, I am saying I wouldn't advise someone to tune their street car at 970 C. I suggested if he thought the exhaust turbine melted, he lower the EGTs to a conservative tune and check his engine compression for signs of internal damage.
Thats not what I said in reference to his turbo melting, what I did say if the wheel cant handle 950, its not the best turbo for a rotary...
It was 950 C 2" from the port. The gas has had more time to expand (heat) and has less boundry layer at the turbine wheel, not to mention the themal build up is higher than the exhaust manifold since its isolated not to mention the frictional forces I talked about earlier. I am thinking the exhaust wheel saw higher temps...
I have run antilag and its not that hot...it peaked at just over 1000 c....
A real anti lag system with air bypass and manifold injection or just retarded timing and rich mix?
I am pretty interested in EGTs as I want to get the GT37 VGT turbo I have to work on the too hot rotary. So its good to discuss and learn.
Okay, this is why I would not advocate tuning for 970 C on a street car. The short bursts with long cool downs of highway pulls WILL NOT put your engine under full thermal loading.
I did the same thing. I tried consecutive zero to redline 5th gear pulls, roll on to redline pulls and finally loading the engine with the brakes and pulling to redline (don't do this its stupid when you have enough power to flatspot your front tires and burn your rears off in 5th). Intake temps were only peaking ~20 C over ambient and coolant temps barely off the 82 C thermostat opening.
Do the same 25 miles on your favorite tortuous mountain road or short circuit and you WILL see much higher thermal loading in all the fluids (intake, oil, coolant, exhaust). I would start driving hard, slow down enough to hit the data log key and continue until I ran out of log. Start with short runs, you may be amazed how quickly your 970 C freeway tune can turn into a 1100 C mistake.
700 c is way to cold, when I first tuned I was seeing that egt with the wideband reading 10.2:1 with 4x1600. The truth it was i t was in the 9's and the lowest reading of the wideband was 10.2, it was running 700 c because it was pig rich, and thats the only reason it was running at that temp..
Too cold for what? If I can do 400HP at ~700 C and only 420HP at 970C I would choose the 400HP. My menatlity is a street car has to be tuned like an endurance race car, not a time attack sprint car. That might be a difference in driving, I like to push a set-up.
970 is the optimum, if you tune to that egt you will most likely find your maximum power there, tuning with egt and g-tech I found this to be so... If your tune is right and your maps smooth and not knotchy jumping all over the places with the air fules, you will find your egt will find its peak, and its tunable to a given egt..
No, that is where YOUR set-up starts losing power due to EGT to intake carry over from overlap when spooling and the trailing plug orfice or too high oil/ coolant temps. Think about that.... You are closer to the edge than you may think in my opinion.
Give it more EGT holding all other factors the same an you will get more HP.
If the Hurleys cant handle 970, they simply dont belong in a rotary period...
If stock seals can only handle 1100 C they don't belong in a performance rotary perion... Ceramics can handle so much more. You understand what I mean?
I have read Mazda sponsored engine builder Darly Drummond talk about how stock apex seals lose hp in one season due to damage on the low performance NA Mazda star spec engines and ceramics hold up great and hold the blueprinted HP.
The point of the side seal being in at zero, if you cant fit a feeler guage in there its msot likely sprung between the two corner seals... I have met RE's engine builder, and he does not "zero clearnace", Zero and .0015 are not the same..And gently breaking it In? whats with that, if its bowed at all it will have a broken side seal from the first day its started...What are you going to do? Keep pulling the motor apart to see if its self clearanced itself?... Start at .0015 and work from there, not zero..
You know you can fit a feeler gauge in there if a sideseal that is so long it binds. 2 corner seals to **** in the bore, the depth of the sidseal slot to misalign the sideseal at each end and the sideseal side clearance to bow the seal in- it adds up to more than .0015 and that is why the feeler gauge isn't the best way to clearance them.
You asked him what to set the sideseals at and he told you .0015? Under Mazda spec, thats telling. Now watch him DO it. Is there a feeler gauge? If someone at my work tells me they are chipping, wearing drill bits fast I would hand them a drill speed chart instead of taking the time to lecture on watching the waste material come off the work and what to look for. You can't summ up "craftsmaship" in a measurement, so you give the quick answer.
You break it in with low thermal and mechanical loading so you don't stress the sideseal before it seats (wears) into the corner seal. Seating into the cornerseal gives you a better gas seal than a straight gap. If you like to break it in with a burnout like Ito run the .007 gap he recommends. His customers would rather be out driving hard right away instead of obscessing about every last bit of sealing from a proper break-in/build. Where do you stand?
Obviously, or you would know the maximum recommended egt of stock seals is 1100 C and you wouldnt be arguing against 970c....
??? I am not saying rebuild your engine if its peaked at 970 C because you have compromised your seals, I am saying I wouldn't advise someone to tune their street car at 970 C. I suggested if he thought the exhaust turbine melted, he lower the EGTs to a conservative tune and check his engine compression for signs of internal damage.
Thats not what I said in reference to his turbo melting, what I did say if the wheel cant handle 950, its not the best turbo for a rotary...
It was 950 C 2" from the port. The gas has had more time to expand (heat) and has less boundry layer at the turbine wheel, not to mention the themal build up is higher than the exhaust manifold since its isolated not to mention the frictional forces I talked about earlier. I am thinking the exhaust wheel saw higher temps...
I have run antilag and its not that hot...it peaked at just over 1000 c....
A real anti lag system with air bypass and manifold injection or just retarded timing and rich mix?
I am pretty interested in EGTs as I want to get the GT37 VGT turbo I have to work on the too hot rotary. So its good to discuss and learn.
08-24-05, 07:56 PM
#30
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Originally Posted by RETed
Since when thermocouples were "different"?
If you knew how thermocouples worked, I find it hard to believe that switching the "polarities" would induce what you described.
Nevermind, Google search works wonders...
http://yarchive.net/electr/thermocouples.html
http://www.branom.com/literature/thermo.html
I think it'll be obvious if it were wired in reverse.
If it's going to spit out a negative signal, the gauge should not even go into the "positive" side of the scale.
As for running calibrated EGT systems...you're right, I just run anything out of Japan.
Shame on me for assuming GReddy, HKS, A'PEXi would all not be calibrated.
-Ted
If you knew how thermocouples worked, I find it hard to believe that switching the "polarities" would induce what you described.
Nevermind, Google search works wonders...
http://yarchive.net/electr/thermocouples.html
http://www.branom.com/literature/thermo.html
I think it'll be obvious if it were wired in reverse.
If it's going to spit out a negative signal, the gauge should not even go into the "positive" side of the scale.
As for running calibrated EGT systems...you're right, I just run anything out of Japan.
Shame on me for assuming GReddy, HKS, A'PEXi would all not be calibrated.
-Ted
You claim you tuned it too 700c, thats 1292 F, or diesel engine territory, didnt that raise any alarm bells for you?.... With egt's at that level, it must be a myth that rotaries need extra heavy exhaust systems to handle extra heat, thats below n/a V_8 gasoline engine EGT..
yes it a thermocouple will go positive to a point in then the indicated temperature will either flatline or start to decline depending on the type of output if the polarity is reversed... I have verified with it my fluke meter thermocouple and my own egt guage... Call Thermokinetics and ask them..
08-24-05, 08:16 PM
#31
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Blue TII, I didnt read you entire post, and I am not going to be honest...
Again I dont do short bursts, I tune with the cruise control on long hills under boost.. I live in South western Alberta Canada, home in the foothills of the Canadian Rocky mountains..
To be honest much of your post is just argumentive bullshit to me, and its not worth my time arguing with you about what you percieve as short pulls and zero clearances....
I have seen rotaries loaded on dynos at boost levels far beyond what you have ever seen and seen them plateau at a given egt pull after pull, so dont try and tell you cant tune for a given egt.. Fire your tuner....It'll be the best thing you will ever do for you car..
Most of the people on this forum are full of it and speak in generalites, because they really dont know, or start arguing the far end of a fart to hide their inexperience on peripheral issues..
Here is the bottome line...
If you are seeing 700 c at WOT, its pig rich, the guage is broke, the probe is in the rear muffler or you are tuning a cummins 5.9 turbo diesel not a rotary..
Everyone wants the tuning secrets of the Japanese tuners, like RE A, ARF, KKM etcl etc etc..
Well there it is, there is one of the big secrets, that is the target egt they shoot for on every rotary when tuning...I have stuck to the lessons and hints they gave me, and I have successfully run a car repeatedly to 20 psi on pump gas, with probably more than 500 full boost pulls over the course over the last 4 months and 14,000 km's...
Once more for those that missed it who want to tune with egt's and are smart enough to calibrate a guage before they trust a motor to it..
Min 850c
Best 970c
Max 1100...
Btw the way if you read Racing beats book guess what it says, 1700-2000 which strangely equates to 923-1093 C....
Wonder where they learned that....Max
Again I dont do short bursts, I tune with the cruise control on long hills under boost.. I live in South western Alberta Canada, home in the foothills of the Canadian Rocky mountains..
To be honest much of your post is just argumentive bullshit to me, and its not worth my time arguing with you about what you percieve as short pulls and zero clearances....
I have seen rotaries loaded on dynos at boost levels far beyond what you have ever seen and seen them plateau at a given egt pull after pull, so dont try and tell you cant tune for a given egt.. Fire your tuner....It'll be the best thing you will ever do for you car..
Most of the people on this forum are full of it and speak in generalites, because they really dont know, or start arguing the far end of a fart to hide their inexperience on peripheral issues..
Here is the bottome line...
If you are seeing 700 c at WOT, its pig rich, the guage is broke, the probe is in the rear muffler or you are tuning a cummins 5.9 turbo diesel not a rotary..
Everyone wants the tuning secrets of the Japanese tuners, like RE A, ARF, KKM etcl etc etc..
Well there it is, there is one of the big secrets, that is the target egt they shoot for on every rotary when tuning...I have stuck to the lessons and hints they gave me, and I have successfully run a car repeatedly to 20 psi on pump gas, with probably more than 500 full boost pulls over the course over the last 4 months and 14,000 km's...
Once more for those that missed it who want to tune with egt's and are smart enough to calibrate a guage before they trust a motor to it..
Min 850c
Best 970c
Max 1100...
Btw the way if you read Racing beats book guess what it says, 1700-2000 which strangely equates to 923-1093 C....
Wonder where they learned that....Max
08-25-05, 12:13 PM
#33
Since you can't/wont process long posts for a meaningful discussion I will keep it short.
Btw the way if you read Racing beats book guess what it says, 1700-2000 which strangely equates to 923-1093 C....
I believe they learned that on NA P-ports with very low backpressure exhausts in race applications.
Since we are talking about Racing Beat; RB states you should mix 22 oz premix w/ 5 gallons gas on a 600hp turbo 2 rotor. Do you do this?
Btw the way if you read Racing beats book guess what it says, 1700-2000 which strangely equates to 923-1093 C....
I believe they learned that on NA P-ports with very low backpressure exhausts in race applications.
Since we are talking about Racing Beat; RB states you should mix 22 oz premix w/ 5 gallons gas on a 600hp turbo 2 rotor. Do you do this?
08-27-05, 02:26 AM
#34
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Originally Posted by Maxthe7man
No, shame on you for tuning with guages you havent verified....
This is why I don't shoot for a number, or do I recommend shooting for a specific number.
I guess if you're all running calibrated meters, then you could recommend shooting for a certain number, but I can't assume that from other people, thus I don't.
Do you blindly trust someone elses wiring, and guages you dont know that are accurate? That is not the hallmarks of someone that tunes engines for a living, do you check the timing lock or jsut trust that the engine is at 5 deg because the laptop says so..
I do verify ignition timing calibration with a timing gun.
If something is amiss, it'll be obvious to me.
You claim you tuned it too 700c, thats 1292 F, or diesel engine territory, didnt that raise any alarm bells for you?.... With egt's at that level, it must be a myth that rotaries need extra heavy exhaust systems to handle extra heat, thats below n/a V_8 gasoline engine EGT..
You're assuming it is, and shoving crap in my face for being so...
Funny, you're blasting me for not using calibrated probes / gauges then turn around blasting me on another point assuming my given numbers are true...
yes it a thermocouple will go positive to a point in then the indicated temperature will either flatline or start to decline depending on the type of output if the polarity is reversed... I have verified with it my fluke meter thermocouple and my own egt guage... Call Thermokinetics and ask them..
I'm not about to cut a polarity coupled EGT probe on a $100+ sensor just to test this theory out.
All the links I've seen showed that the gauge should go the opposite way - it makes sense, as the thermocouple generates a minute voltage potential.
It's like connecting a batter backwards - negative voltage.
-Ted
08-27-05, 02:27 AM
#35
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Originally Posted by Maxthe7man
Btw the way if you read Racing beats book guess what it says, 1700-2000 which strangely equates to 923-1093 C....
Wonder where they learned that....Max
Wonder where they learned that....Max
Since when RB quoted these numbers for TURBO engines?
Do we need to explain why NA and turbo engines run a different EGT's?
-Ted
08-27-05, 06:32 AM
#36
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Originally Posted by RETed
Wow, Max you really stuck your foot into that one.
Since when RB quoted these numbers for TURBO engines?
Do we need to explain why NA and turbo engines run a different EGT's?
-Ted
Since when RB quoted these numbers for TURBO engines?
Do we need to explain why NA and turbo engines run a different EGT's?
-Ted
Read your Racing beat Catalog... Its in there...
By the way that was a nice stack of pretty lame excuses for weaseling out of what you tirading about before..
You never claimed your 700C was a "true" 700c?... Then why ******* post it then?...
Put this in your sig.."I am spewing numbers and info which may or may not be accurate, depending on what I am arguing about at this current time"...
If you want to argue about generalities find someone else with as much free time as you have... I have posted what specific egt's should be on a good tune for T.I.T., if you dont like the numbers , dont use them....
Last edited by Maxthe7man; 08-27-05 at 06:52 AM.
09-06-05, 04:32 PM
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Ii have removed the centre of my GT42/51R and blanked the front of the turbine housing,so now running with no boost,remapped to suit.
Exhaust is 3 1/2" to the rear axle,then 3" over the axle and out through a short 3" hks box.Yes,it is loud.
I have connected a boost gauge to where my egt probe was,2" from the port.
When driving on light throttle,I see 5-6 psi exhaust pressure.
Is it that the turbo turbine housing is way too restrictive? Will be doing more testing tomorrow.
Exhaust is 3 1/2" to the rear axle,then 3" over the axle and out through a short 3" hks box.Yes,it is loud.
I have connected a boost gauge to where my egt probe was,2" from the port.
When driving on light throttle,I see 5-6 psi exhaust pressure.
Is it that the turbo turbine housing is way too restrictive? Will be doing more testing tomorrow.
09-06-05, 08:54 PM
#38
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What a/r and trim is the rear housings, and is it divided or not?..that seems like alot of backpressure for such a large system... The standard that I would have to say 99% of the tuners and turbo sizers use for back pressure in Japan is no more than .3 bar over manifold pressure, anymore than that and its considered to be unbalanced via turbine to compressor sizing and not a good system to use the compressor to its maximum boost pressure and efficiency..
Is the pickup for pressure angled into flow or perpendicular, just wonder if you are pickin up velocity pressure as well as static...
Is the pickup for pressure angled into flow or perpendicular, just wonder if you are pickin up velocity pressure as well as static...
09-07-05, 04:27 PM
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.91 exhaust A/R,divided.Pressure is from a spigot screwed in where the egt probe was,then connected to my AVC-R.Today I read 11psi at 7000 rpm.Pressure is zero on idle,then stays at 3-4 psi til 4000 rpm,then it climbs.
09-07-05, 07:50 PM
#40
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i have logged exhaust manifold pressure (EMP) for approx 5000 miles along with 2 egts. all pre turbo. or preturbos as i run 2 TO4s.
currently i find about 3 psi backpressure off idle and 14 psi at one bar boost. prior to going larger w my hotsides i had 30 psi at one bar.
as to egts....
i ran Roger Mandeville and Daryl Drummond's motors for my 6 years of GT3 SCCA Nats. they were 12A dry sump NA Bridgeported motors that were restricted to 38 mm chokes in the two venturis of a Weber downdraft. the motors made 259 flywheel hp at between 7 and 10,000 rpm. i tuned them daily by noting EGT (approx 5 inches from port) in top gear at the end of the longest straight and jetting for 1750.
my guess is that this is too hot for a turbo'd rotary. my friend who makes about 800 rear wheel rotary hp ( meth peri port) and does it w shocking reliability tunes a bunch of gas cars too. he says 1630-1650 is optimum. based on previous advice to me which has proved out and his record that's good enough for me.
currently i am tuning just under one bar and i am seeing 1750 1850 up top and i have messed w just about everything to reduce it. i am at 11 degrees w 14 split at the moment. tomorrow i am going to videotape the egt 10 volt feed as perhaps my calibration is off a bit.
howard coleman
currently i find about 3 psi backpressure off idle and 14 psi at one bar boost. prior to going larger w my hotsides i had 30 psi at one bar.
as to egts....
i ran Roger Mandeville and Daryl Drummond's motors for my 6 years of GT3 SCCA Nats. they were 12A dry sump NA Bridgeported motors that were restricted to 38 mm chokes in the two venturis of a Weber downdraft. the motors made 259 flywheel hp at between 7 and 10,000 rpm. i tuned them daily by noting EGT (approx 5 inches from port) in top gear at the end of the longest straight and jetting for 1750.
my guess is that this is too hot for a turbo'd rotary. my friend who makes about 800 rear wheel rotary hp ( meth peri port) and does it w shocking reliability tunes a bunch of gas cars too. he says 1630-1650 is optimum. based on previous advice to me which has proved out and his record that's good enough for me.
currently i am tuning just under one bar and i am seeing 1750 1850 up top and i have messed w just about everything to reduce it. i am at 11 degrees w 14 split at the moment. tomorrow i am going to videotape the egt 10 volt feed as perhaps my calibration is off a bit.
howard coleman
09-07-05, 08:30 PM
#41
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Hmm strange I posted and it never showed up..
Howard your present Back pressure sounds about right..
TimRx: the standard T51 is a 1.0 undivided.. Thats a wierd kinda housing, is that the GT stuff?.. I will have to tap into mine and see what its at , at 20 psi boost..
1750 sounds about right in the magic ballpark, thats like 950 somthing for egt's ..
The egt will be cooler somewhat with methanol, at least is should be..
The fueling I find has the greatest influence on it a rotary.. Some poeple claim to tune by egt only, with no a/f guage, Its a see/saw with egt, they will cool off as it goes to lean as well as well as overly rich..You have to make sure you know which direction you are going in..
At one point my egt's were in the 800's, and the a/f was always reading 10.5:1, then I kept removing fuel till Is saw the peak boost egt finally start moving upward towards 900 at around the 9 teens, the a/f guage started to read 10.7-10.8 and I realized my a/f guage was pinned rich at 10.5 and thats as rich as it would read..
Stoich will be the highest egt, but will also change with load.. Cruise egt will not be the highest egt since its not the highest load, if we loaded the motor to 100% at stoich, then that would be the peak egt, we dont do that though since it would knock..
My boost egt's given a long enough boost pull come out to mid 900's my cruise 750C and idle is 600c... Underhood and intake air temps seem play no bearing on egt's, mine are the same now at cold morning runs (+2 C) as they were at (30+C)...The wonders of intake air temp mapping...Max
Howard your present Back pressure sounds about right..
TimRx: the standard T51 is a 1.0 undivided.. Thats a wierd kinda housing, is that the GT stuff?.. I will have to tap into mine and see what its at , at 20 psi boost..
1750 sounds about right in the magic ballpark, thats like 950 somthing for egt's ..
The egt will be cooler somewhat with methanol, at least is should be..
The fueling I find has the greatest influence on it a rotary.. Some poeple claim to tune by egt only, with no a/f guage, Its a see/saw with egt, they will cool off as it goes to lean as well as well as overly rich..You have to make sure you know which direction you are going in..
At one point my egt's were in the 800's, and the a/f was always reading 10.5:1, then I kept removing fuel till Is saw the peak boost egt finally start moving upward towards 900 at around the 9 teens, the a/f guage started to read 10.7-10.8 and I realized my a/f guage was pinned rich at 10.5 and thats as rich as it would read..
Stoich will be the highest egt, but will also change with load.. Cruise egt will not be the highest egt since its not the highest load, if we loaded the motor to 100% at stoich, then that would be the peak egt, we dont do that though since it would knock..
My boost egt's given a long enough boost pull come out to mid 900's my cruise 750C and idle is 600c... Underhood and intake air temps seem play no bearing on egt's, mine are the same now at cold morning runs (+2 C) as they were at (30+C)...The wonders of intake air temp mapping...Max
09-07-05, 08:58 PM
#42
1600 to 1650 deg farenheit works best for me on gasolene measured six inches away from the exhaust port on a turbo application at full sustained load normaly redline in high gear for at least 1/2 mile.
On methanol egt's are a lot cooler. On turbo/methanol applications I've not discovered an exact sitting but it normaly is somewhere 300 to 400 deg F. cooler. On NA/methanol applications 1400 deg. F seems to be the lean limit. Anything higher/leaner results in misfire on my application.
On methanol egt's are a lot cooler. On turbo/methanol applications I've not discovered an exact sitting but it normaly is somewhere 300 to 400 deg F. cooler. On NA/methanol applications 1400 deg. F seems to be the lean limit. Anything higher/leaner results in misfire on my application.
Last edited by crispeed; 09-07-05 at 09:00 PM.
09-11-05, 10:54 AM
#44
Rebreaking things
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FWIW that looks very similar to my damaged P trim wheel. I believe I sent something through it when the motor blew, but I'm not certain of that. I run 14.5-15:1 afrs at cruising speed, 11.3 @ 15psi with 13-14 deg L 12 deg of split.
Last edited by CCarlisi; 09-11-05 at 11:07 AM.
09-11-05, 09:09 PM
#45
Originally Posted by timrxmotors
A pic of the melting turbine wheel.The inside of the wheel should be as wide as the plate behind it.At the points it seems to melt into tiny ***** of metal.
09-11-05, 09:22 PM
#46
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Originally Posted by crispeed
Have you checked to see if there's difference in egt's from front to rear rotor?
TimRX is this from the motor with the mystery magic internal coating? Is it that stuff coming off going through the turbine?.. But the edges are definite soft bent melted..
On the subject of coated parts, if you stop the internal parts from picking up heat, the heat ends up going somewhere, probably increased egt's...
Last edited by Maxthe7man; 09-11-05 at 09:25 PM.
09-12-05, 03:23 PM
#47
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I have measured egt on the front rotor,as that one appears to run hotter,plugs and exhaust port colour are identical,I have no reason to think the rear rotor could have higher egt.
With this turbo,the first engine had the mystery coated rotor housings,that came apart when the coating disappeared.
The 2nd engine broke an apex seal in half for no apparent reason on the rolling road.When stripped,I found many deep scores above both exhaust ports,and bits embedded in both rotors Didn't make sense from one broken seal.
The 3rd engine ran crap when given full throttle,egt guage was fitted,and engine was misfiring above 750c.Stripped it to find more scoring above the exhaust ports,more embedded bits,one causing an apex seal to jam when hot.
Found turbo to be melting,and it appears the molten bits are rolling back into the engine,responsible for destroying 2 engines.
The present engine is fine,no turbo,just the turbine housing.Waiting for an HKS T51 kai,what I should have bought to start with.The GT42/51R is no good for a rotary.
With this turbo,the first engine had the mystery coated rotor housings,that came apart when the coating disappeared.
The 2nd engine broke an apex seal in half for no apparent reason on the rolling road.When stripped,I found many deep scores above both exhaust ports,and bits embedded in both rotors Didn't make sense from one broken seal.
The 3rd engine ran crap when given full throttle,egt guage was fitted,and engine was misfiring above 750c.Stripped it to find more scoring above the exhaust ports,more embedded bits,one causing an apex seal to jam when hot.
Found turbo to be melting,and it appears the molten bits are rolling back into the engine,responsible for destroying 2 engines.
The present engine is fine,no turbo,just the turbine housing.Waiting for an HKS T51 kai,what I should have bought to start with.The GT42/51R is no good for a rotary.
09-12-05, 08:28 PM
#49
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Originally Posted by timrxmotors
A pic of the melting turbine wheel.The inside of the wheel should be as wide as the plate behind it.At the points it seems to melt into tiny ***** of metal.
The cup which sits behind the turbine wheel also shows pitting from foreign debris.
You will warp seals from excessive heat before melting a turbine wheel.
Was this turbo used on those 3 broken motors??
09-13-05, 02:50 PM
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Originally Posted by dubulup
call me crazy, but how can turbine blade chunks travel into a motor that is running?