Increasing tC's Rev Limit?
09-19-2005, 09:41 PM
#25
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20 years ago that would have been amazing. Ever see a Prolong infomercial? They really do run those things without oil. It's a testament to the quality of the materials used in the engines compared to years gone by. It never ceases to amaze me how far engine technology has come since I started playing with them 25 years ago.
Oh, FWIW, there's no load on the engine. If he'd've been doing 1/4 mile passes at WOT with water in there, it would have spit out a rod on the first run. That's what that clank at the end is. AMHIK.
Oh, FWIW, there's no load on the engine. If he'd've been doing 1/4 mile passes at WOT with water in there, it would have spit out a rod on the first run. That's what that clank at the end is. AMHIK.
09-19-2005, 11:19 PM
#26
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Originally Posted by lo_bux_racer
Mean piston speed is the problem, the 2AZ hits 20 meters per second at exactly 6250 rpm. Mean piston speed over 20 meters per second means shorter service life.
Yes, I know very well the Integra Type R's mean piston speed goes up to 24 meters/second, but I also know they designed the rest of the engine to do that. Conservative engineering practice (Toyco's founding principle) says redline at 20 meters/second (6250 rpm) will last at least 200,000 miles.
This is true of all engines from the smallest model airplanes to the largest container ships. Mean piston speed determines the true rpm limit, not valve springs. If your valves float before you hit 20 meters/second, your engine has not been well designed. Toyco's legendary 2JZ-GTE and 3S-GTE engines are not limited by their valvetrain in stock form, they are limited by mean piston speed.
Still, you can rev the 2AZ to 7500 rpm and not exceed 24 m/sec mean piston speed. Why is it a waste of time right now? Because the head won't move enough air to keep the torque up above the current hp peak. If you put in bigger valves and do the commensurate port work, put in bigger cams and the appropriate springs/retainers, and dramatically increase the size of the rest of the intake and exhaust, then you won't see the torque drop off at higher rpm and you'll make more power up top.
Of course when you do this, you sacrifice port velocity at lower rpm, so your power at lower rpm will suffer. Ever wonder how it is that an F1 engine never revs below 10,000 rpm? Big ports moving lots of air at very high rpm, making torque where they can to get the power to win. Those are the same type of compromises you will make with the 2AZ if you want more power at high rpm.
Yes, I know very well the Integra Type R's mean piston speed goes up to 24 meters/second, but I also know they designed the rest of the engine to do that. Conservative engineering practice (Toyco's founding principle) says redline at 20 meters/second (6250 rpm) will last at least 200,000 miles.
This is true of all engines from the smallest model airplanes to the largest container ships. Mean piston speed determines the true rpm limit, not valve springs. If your valves float before you hit 20 meters/second, your engine has not been well designed. Toyco's legendary 2JZ-GTE and 3S-GTE engines are not limited by their valvetrain in stock form, they are limited by mean piston speed.
Still, you can rev the 2AZ to 7500 rpm and not exceed 24 m/sec mean piston speed. Why is it a waste of time right now? Because the head won't move enough air to keep the torque up above the current hp peak. If you put in bigger valves and do the commensurate port work, put in bigger cams and the appropriate springs/retainers, and dramatically increase the size of the rest of the intake and exhaust, then you won't see the torque drop off at higher rpm and you'll make more power up top.
Of course when you do this, you sacrifice port velocity at lower rpm, so your power at lower rpm will suffer. Ever wonder how it is that an F1 engine never revs below 10,000 rpm? Big ports moving lots of air at very high rpm, making torque where they can to get the power to win. Those are the same type of compromises you will make with the 2AZ if you want more power at high rpm.
09-20-2005, 02:05 PM
#27
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Originally Posted by ZPIracing
We have reved the tC to 11k with out incident. We rev to 7500 on our shop car daily.
We would suggest that a 7k RPM rev limiter would be safe and ideal for daily driving. We make peak power at Redline on all stage 1 dynos. So to say that the car is not making any power past the 6250 mark is incorrect. Unless you have dynoed the car and tested this theory.
With a stock head or are head package I would suggest 7k is a safe range. 6800 for sure. We go to 7500 on a abused engine with 10k of the hardest miles known to any Scion and she is still going strong.
The ultimate is a great device there are still some bugs that needs to be worked out when using it on the tC. We have been in close contact with Greddy on this and will hopefully have the settings down by the time you all would want one.
Thanks
-Kenny
We would suggest that a 7k RPM rev limiter would be safe and ideal for daily driving. We make peak power at Redline on all stage 1 dynos. So to say that the car is not making any power past the 6250 mark is incorrect. Unless you have dynoed the car and tested this theory.
With a stock head or are head package I would suggest 7k is a safe range. 6800 for sure. We go to 7500 on a abused engine with 10k of the hardest miles known to any Scion and she is still going strong.
The ultimate is a great device there are still some bugs that needs to be worked out when using it on the tC. We have been in close contact with Greddy on this and will hopefully have the settings down by the time you all would want one.
Thanks
-Kenny
thanks for posting this info. i felt confident about the motor w/ stock internals from other threads, but this just brings it to another level.
i guess only time will tell, but so far it's nice to know the motor can take a beating and then some! keep up the great work.
Originally Posted by TurboCustomz
The torque did not fall off at any more of an exponential rate between 6250 and 7000 then it did between 4850 and 6250. Besides, in the upper RPM when torque falls off is when HP takes over and actually moves the car.
that's exactly what i was thinking.....
09-20-2005, 08:20 PM
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Thats a lot of nice technical jargin. I dont think its a waste to rev the car to 7k at all. Why? My car made peak power at the 7k redline that I had it set to at the time. Did I sacrifice tq? No, not at all. The torque did not fall off at any more of an exponential rate between 6250 and 7000 then it did between 4850 and 6250. Besides, in the upper RPM when torque falls off is when HP takes over and actually moves the car.
Torque should be flat, or in the case of racing engines, optimised to peak in the rpm range where you expect to spend most of your time. When it starts to drop off the rate of hp increase also starts to drop until the torque no longer makes enough hp to warrant keeping the throttle open. Torque is measured. Hp is calculated from torque, so saying hp "takes over" after torque falls off makes no sense.
If the torque were flat, then you would make more power at 7000 rpm than you do at 6250. That is not true because the torque falls off, and in the stock configuration hp peaks below 6000 rpm. Are you saying your engine magically has a second torque peak above 6000 rpm that produces more hp than the engine does at 6000 rpm? Or are you saying you've significantly modified from the stock configuration, and now you make peak power at 7,000 rpm? Again, your statement makes no sense in terms of the stock engine configuration.
09-20-2005, 08:58 PM
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Originally Posted by lo_bux_racer
Thats a lot of nice technical jargin. I dont think its a waste to rev the car to 7k at all. Why? My car made peak power at the 7k redline that I had it set to at the time. Did I sacrifice tq? No, not at all. The torque did not fall off at any more of an exponential rate between 6250 and 7000 then it did between 4850 and 6250. Besides, in the upper RPM when torque falls off is when HP takes over and actually moves the car.
Torque should be flat, or in the case of racing engines, optimised to peak in the rpm range where you expect to spend most of your time. When it starts to drop off the rate of hp increase also starts to drop until the torque no longer makes enough hp to warrant keeping the throttle open. Torque is measured. Hp is calculated from torque, so saying hp "takes over" after torque falls off makes no sense.
If the torque were flat, then you would make more power at 7000 rpm than you do at 6250. That is not true because the torque falls off, and in the stock configuration hp peaks below 6000 rpm. Are you saying your engine magically has a second torque peak above 6000 rpm that produces more hp than the engine does at 6000 rpm? Or are you saying you've significantly modified from the stock configuration, and now you make peak power at 7,000 rpm? Again, your statement makes no sense in terms of the stock engine configuration.
09-21-2005, 02:28 PM
#31
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"When it starts to drop off the rate of hp increase also starts to drop"
That still does not disprove the fact that I can make peak horsepower at redline when its set at 7K rpms.
"Torque should be flat, or in the case of racing engines, optimised to peak in the rpm range where you expect to spend most of your time."
Torque will never be flat. You cannot expect to make the same torque at 1500 rpms as you do at 4K. Only half of your sentence is correct. Optimally, you want the engine to peak horsepower at your shift points, and peak torque right around where your rpms fall into your next shift.
"If the torque were flat, then you would make more power at 7000 rpm than you do at 6250. That is not true because the torque falls off, and in the stock configuration hp peaks below 6000 rpm."
Yes, in the stock configuration it does. I believe we have posted SEVERAL dyno sheets on THIS FORUM that show us making peak HP at redline on these cars. Obviously my car isn't stock, obviously your not talking about the same thing that I am. Read, think, type. Not read, cut and paste, try to look smart.
Thanks you. Have a nice day. Loveyoubye.
Charles
That still does not disprove the fact that I can make peak horsepower at redline when its set at 7K rpms.
"Torque should be flat, or in the case of racing engines, optimised to peak in the rpm range where you expect to spend most of your time."
Torque will never be flat. You cannot expect to make the same torque at 1500 rpms as you do at 4K. Only half of your sentence is correct. Optimally, you want the engine to peak horsepower at your shift points, and peak torque right around where your rpms fall into your next shift.
"If the torque were flat, then you would make more power at 7000 rpm than you do at 6250. That is not true because the torque falls off, and in the stock configuration hp peaks below 6000 rpm."
Yes, in the stock configuration it does. I believe we have posted SEVERAL dyno sheets on THIS FORUM that show us making peak HP at redline on these cars. Obviously my car isn't stock, obviously your not talking about the same thing that I am. Read, think, type. Not read, cut and paste, try to look smart.
Thanks you. Have a nice day. Loveyoubye.
Charles
09-22-2005, 12:06 AM
#32
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Originally Posted by TurboCustomz
Torque will never be flat. You cannot expect to make the same torque at 1500 rpms as you do at 4K. ...
Charles
Charles
09-22-2005, 02:09 AM
#33
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TurboCustomz:
Your knowledge of engines is seriously limited. The things you say show incredible ignorance and prejudice. You really shouldn't say torque is never flat. Look at any number of domestics that produce phenomenally flat torque curves and steadily increasing hp, and yes, I certainly can expect to see the same torque at 1.5k rpm that I see at 5k rpm, there are lots of engines doing it everyday.
Also, don't assume I have any interest in your specific configuration when you don't even use it as a qualifier for your less than intelligent statements.
Last but not least, shifting at your hp peak and expecting to fall back to your torque peak worked in the 30's before they figured out all the torque and hp stuff. Since then, they've determined optimum shift points are entirely based on hp. You owe it to yourself to do some homework on this, it will make you faster at the track.
Here's a link to help you grasp the concept of modern shift point calculation.
Your knowledge of engines is seriously limited. The things you say show incredible ignorance and prejudice. You really shouldn't say torque is never flat. Look at any number of domestics that produce phenomenally flat torque curves and steadily increasing hp, and yes, I certainly can expect to see the same torque at 1.5k rpm that I see at 5k rpm, there are lots of engines doing it everyday.
Also, don't assume I have any interest in your specific configuration when you don't even use it as a qualifier for your less than intelligent statements.
Last but not least, shifting at your hp peak and expecting to fall back to your torque peak worked in the 30's before they figured out all the torque and hp stuff. Since then, they've determined optimum shift points are entirely based on hp. You owe it to yourself to do some homework on this, it will make you faster at the track.
Here's a link to help you grasp the concept of modern shift point calculation.
09-22-2005, 02:51 AM
#34
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By saying HP takes over where torque falls off isn't entirely false. You'd have to be at a high engine speed but so long as tq is above 0 than HP will still be made after the tq peak.
In order to make stock HP at 7000 rpm you'd have to make 120 lbs/ft. Hm..
Well how about this, if you make 100 lbs/ft at 8.5k rpm you'd still be making 160~ hp. Still not good..
So.. at 15k rpm you'd only need about 56 lbs/ft to make stock hp.
You know what, lo_bux_racer? I think you're right.
In order to make stock HP at 7000 rpm you'd have to make 120 lbs/ft. Hm..
Well how about this, if you make 100 lbs/ft at 8.5k rpm you'd still be making 160~ hp. Still not good..
So.. at 15k rpm you'd only need about 56 lbs/ft to make stock hp.
You know what, lo_bux_racer? I think you're right.
09-22-2005, 03:34 AM
#35
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The engine builders edict: build for best torque in the rpm range you expect to use most. But that's not mine. John Lingenfelter preached that years ago in his book about building small block Chevrolets. It doesn't matter who manufactured the engine, the principle never changes.
This link underscores the whole issue of torque, rpm, and real power. Also, the idea that you want to make best torque at your normal operating rpm.
Pics of this thing are here. Oh, yeah, it's got a turbo too.
This link underscores the whole issue of torque, rpm, and real power. Also, the idea that you want to make best torque at your normal operating rpm.
Pics of this thing are here. Oh, yeah, it's got a turbo too.
09-22-2005, 04:33 AM
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Originally Posted by lo_bux_racer
TurboCustomz:
Your knowledge of engines is seriously limited. The things you say show incredible ignorance and prejudice. You really shouldn't say torque is never flat. Look at any number of domestics that produce phenomenally flat torque curves and steadily increasing hp, and yes, I certainly can expect to see the same torque at 1.5k rpm that I see at 5k rpm, there are lots of engines doing it everyday.
Also, don't assume I have any interest in your specific configuration when you don't even use it as a qualifier for your less than intelligent statements.
Last but not least, shifting at your hp peak and expecting to fall back to your torque peak worked in the 30's before they figured out all the torque and hp stuff. Since then, they've determined optimum shift points are entirely based on hp. You owe it to yourself to do some homework on this, it will make you faster at the track.
Here's a link to help you grasp the concept of modern shift point calculation.
Your knowledge of engines is seriously limited. The things you say show incredible ignorance and prejudice. You really shouldn't say torque is never flat. Look at any number of domestics that produce phenomenally flat torque curves and steadily increasing hp, and yes, I certainly can expect to see the same torque at 1.5k rpm that I see at 5k rpm, there are lots of engines doing it everyday.
Also, don't assume I have any interest in your specific configuration when you don't even use it as a qualifier for your less than intelligent statements.
Last but not least, shifting at your hp peak and expecting to fall back to your torque peak worked in the 30's before they figured out all the torque and hp stuff. Since then, they've determined optimum shift points are entirely based on hp. You owe it to yourself to do some homework on this, it will make you faster at the track.
Here's a link to help you grasp the concept of modern shift point calculation.
P.S. at no time during this conversation, was I talking about a STOCK car. Obviously.
09-22-2005, 06:18 AM
#37
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Great, now it's a misunderstanding.
So stop arguing because there was a minor detail missing from the start?
If you look, the two of you haven't REALLY contradicted eachother so much as saying almost the same thing slightly differently.
Peace?
So stop arguing because there was a minor detail missing from the start?
If you look, the two of you haven't REALLY contradicted eachother so much as saying almost the same thing slightly differently.
Peace?
09-22-2005, 06:29 AM
#38
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not to be the nitpickin spellchecker.. but jargon -- not jargin.. that's just terms associated with whatever subject you're talking about.
other than that... i dont know too much techinical stuff about engines so.. you guys take care of that haha
other than that... i dont know too much techinical stuff about engines so.. you guys take care of that haha
09-22-2005, 06:31 AM
#39
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Originally Posted by TurboCustomz
P.S. at no time during this conversation, was I talking about a STOCK car. Obviously.
No, your life doesn't suck; I never said anything like that. How many championships have you won in what series?
Seriously, your statement about torque, horsepower, and shift points was "common wisdom" in the 50's, 60's and 70's. I know, I used to think the same thing because the same people who were supposed to be the gurus were saying it was fact. It just isn't true, and the physics guys have laid it all out so you know it isn't right.
Just as you know reving a tC to 7k without supporting mods to the intake and exhaust is pointless.
I wouldn't have said a word if you'd said, my modified tC makes peak power at 7k. I surely don't know you, and you surely don't know me. I had no idea you are associated with ZPI until I researched your history. Had I known, I'd've asked what you've done that you are willing to talk about. Just like I asked about your headwork. I didn't say anything bad about it, or question the work, I just asked for more information. I'd've done the same thing if you'd put a single qualifier in your statement. Thanks for clearing it up.
FWIW, I grew up with circle track racing, and I've been building engines for street and competition use since before you were born. I've been porting cylinder heads since you were 8. I've believed lots of manufacturer's and tuner's claims and found them to be nothing but marketing hype with no real gains, some were even worse than stock. Most important, I believe when the green flag drops the BS stops, and second place is the first loser to cross the finish line. Last but not least, I don't do what you do for a living. There's no money in it. Lots of fun, but no money.
09-22-2005, 02:34 PM
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Originally Posted by kungpaosamuraiii
Great, now it's a misunderstanding.
So stop arguing because there was a minor detail missing from the start?
If you look, the two of you haven't REALLY contradicted eachother so much as saying almost the same thing slightly differently.
Peace?
So stop arguing because there was a minor detail missing from the start?
If you look, the two of you haven't REALLY contradicted eachother so much as saying almost the same thing slightly differently.
Peace?
We weren't really arguing in the first place. I happen to like a stimulating conversation with someone else that is educated that has slightly different views and opinions. Albeit, to tell someone else that they are completely wrong and that their way is the only way is slightly pompus, imo.
In either event, we have almost made peak HP at the stock redline with our stage 0 turbo kit. I'd like to see where the power increase stops. At the time, we didnt have the ability to raise the stock limiter. Guess we'll have to try it and see. Completely stock car, bolt on turbo kit, 7K rev limit. If I have the opportunity, I'll get this done and post up the results. Just for curiosity sake.
Originally Posted by lo_bux_racer
Most important, I believe when the green flag drops the BS stops, and second place is the first loser to cross the finish line.
Originally Posted by lo_bux_racer
Last but not least, I don't do what you do for a living. There's no money in it. Lots of fun, but no money.