Restrictor plate in BEGi exhaust
03-11-2015, 08:33 AM
#101
Loads: Get a plot of chamber pressure vs crank angle. Multiply piston area times chamber pressure at every degree and plot. At each degree of crank angle, calc the inertial loads. Plot. Add the two loads together for every degree for a total load. Calc column buckling strength of the con rod. Take worst case compressive sum and adjust boost (reflecting pressure load) and rpm (inertial load) to stay below the column buckling load.
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03-11-2015, 09:37 AM
#104
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The "5252" factor would only come in when specific units are attached to the formula. If power were in KW, and torque were in N-cm, then the acutal number would be something else.
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03-11-2015, 10:19 AM
#105
I sort of thought that might be the case the first time I read it. I realize it was unit-less now that I went back and read it a second time. I searched around the internet for a bit, but didn't (easily) find confirmation that the 5252 can be disregarded when your factors are unitless.
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03-11-2015, 11:35 PM
#106
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Not just stock rods, it could be a stock 5 speed, or having 225/45/15 street tires instead of fender flares and 275/35/15 race rubber, a lot of factors go into this. I am very traction limited on 225's with 280 wheel HP, I can't imagine it being better with 350 WHP on those same 225's.
I am talking about boost creep, not boost overshoot.
Nitrodann, if you honestly don't understand why someone would want functional boost control where you can set it at your goal boost and not have it creep then why do you have a wastegate? One of the reasons I want to get ride of creep is so I can have what you have... controlled rise in boost pressure as RPM's rise.
Your entire argument is based on you having a system that does not have boost creep and asking us why we want a system that functions as well as yours does. I know you don't have boost creep because if you did you couldn't have controlled rise in boost pressure as RPM's rise, you would have uncontrolled rise in boost pressure as RPM's rise.
Keith
I am talking about boost creep, not boost overshoot.
Nitrodann, if you honestly don't understand why someone would want functional boost control where you can set it at your goal boost and not have it creep then why do you have a wastegate? One of the reasons I want to get ride of creep is so I can have what you have... controlled rise in boost pressure as RPM's rise.
Your entire argument is based on you having a system that does not have boost creep and asking us why we want a system that functions as well as yours does. I know you don't have boost creep because if you did you couldn't have controlled rise in boost pressure as RPM's rise, you would have uncontrolled rise in boost pressure as RPM's rise.
Keith
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03-11-2015, 11:46 PM
#107
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My current turbo is V-band clamp, so I would need A/O setup for V-band on booth the manifold and downpipe.
You mentioned that I would need modifications to the turbo to run it on the A/O system, that is why I mentioned it was a V-band housing and that I have modified the clocking of the compressor housing... trying to clarify what turbo modifications would I need to make to run my current turbo (spud with tial V-band turbine housing) on the A/O system so I know if it is something I can do, or if I need to send it in to you.
Keith
You mentioned that I would need modifications to the turbo to run it on the A/O system, that is why I mentioned it was a V-band housing and that I have modified the clocking of the compressor housing... trying to clarify what turbo modifications would I need to make to run my current turbo (spud with tial V-band turbine housing) on the A/O system so I know if it is something I can do, or if I need to send it in to you.
Keith
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03-12-2015, 12:28 AM
#108
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Not just stock rods, it could be a stock 5 speed
My original example given in this thread is a 280whp NA8 VVT with a 5 speed, yes i agree.
, or having 225/45/15 street tires instead of fender flares and 275/35/15 race rubber, a lot of factors go into this. I am very traction limited on 225's with 280 wheel HP, I can't imagine it being better with 350 WHP on those same 225's.
you still arent quite getting this, WHP alone has absolutely **** all to do with traction, once again, its all about the peak torque (in this case at the tyres).
Lets do some numbers. 250ft lb is the number usually used as the limit of both 5 speeds and stock rods. In my experience cars with stock engines are not significantly traction limited on stock engines, with 225 street legal tyres, and a non fucked up setup. 240 ft lb (im using a small safety margin here) is over 340rwhp at 7500rpm.
If it makes traction with that torque at 4000 itll make it at 7500.
I am talking about boost creep, not boost overshoot.
Nitrodann, if you honestly don't understand why someone would want functional boost control where you can set it at your goal boost and not have it creep then why do you have a wastegate? One of the reasons I want to get ride of creep is so I can have what you have... controlled rise in boost pressure as RPM's rise.
Your entire argument is based on you having a system that does not have boost creep and asking us why we want a system that functions as well as yours does. I know you don't have boost creep because if you did you couldn't have controlled rise in boost pressure as RPM's rise, you would have uncontrolled rise in boost pressure as RPM's rise.
Keith
My original example given in this thread is a 280whp NA8 VVT with a 5 speed, yes i agree.
, or having 225/45/15 street tires instead of fender flares and 275/35/15 race rubber, a lot of factors go into this. I am very traction limited on 225's with 280 wheel HP, I can't imagine it being better with 350 WHP on those same 225's.
you still arent quite getting this, WHP alone has absolutely **** all to do with traction, once again, its all about the peak torque (in this case at the tyres).
Lets do some numbers. 250ft lb is the number usually used as the limit of both 5 speeds and stock rods. In my experience cars with stock engines are not significantly traction limited on stock engines, with 225 street legal tyres, and a non fucked up setup. 240 ft lb (im using a small safety margin here) is over 340rwhp at 7500rpm.
If it makes traction with that torque at 4000 itll make it at 7500.
I am talking about boost creep, not boost overshoot.
Nitrodann, if you honestly don't understand why someone would want functional boost control where you can set it at your goal boost and not have it creep then why do you have a wastegate? One of the reasons I want to get ride of creep is so I can have what you have... controlled rise in boost pressure as RPM's rise.
Your entire argument is based on you having a system that does not have boost creep and asking us why we want a system that functions as well as yours does. I know you don't have boost creep because if you did you couldn't have controlled rise in boost pressure as RPM's rise, you would have uncontrolled rise in boost pressure as RPM's rise.
Keith
EDIT: Here is the boost map (duty cycle) used on the 280whp GT2560r 5 speed car, blurred out everything but the part in question, the full throttle part of the map.
That above map is directly off the tune, this below image is the with changes made to show what it looks like on a similar setup that has a little creep like the 5 psi at redline we have been discussing.
IE; in this thread, the creep being discussed is less that you actually want for peak performance and therefor is fine, in the exact same way that a 7psi WGA is fine even though it wont allow you to have less than 7 psi.
Dann
Last edited by nitrodann; 03-12-2015 at 01:08 AM.
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03-14-2015, 07:52 AM
#109
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2d, roger, you can handle it. Outline needs later.
Power is defined as force times velocity. There are a several variations. Two are; torque times rpm, and pressure times volume rate of flow.
corky
Power is defined as force times velocity. There are a several variations. Two are; torque times rpm, and pressure times volume rate of flow.
corky
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03-14-2015, 03:31 PM
#113
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At 7000 RPM doing the math you see that each compression event only lasts 2.15 milliseconds.
As was pointed out to me in another thread, if you have the same torque output from the engine at two different RPM's the higher piston speed moving away from the flame front at higher RPMs reduces the peak load on the rods even at the same total torque output.
Keith
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03-14-2015, 04:21 PM
#114
....
As was pointed out to me in another thread, if you have the same torque output from the engine at two different RPM's the higher piston speed moving away from the flame front at higher RPMs reduces the peak load on the rods even at the same total torque output.
Keith
As was pointed out to me in another thread, if you have the same torque output from the engine at two different RPM's the higher piston speed moving away from the flame front at higher RPMs reduces the peak load on the rods even at the same total torque output.
Keith
Basically if you measure cylinder pressure vs crank position and plot that at both RPM points, for the same torque, the motor turning slower will have higher peak pressure, as the 10-90% combustion time will occur with the piston closer to TDC than an engine turning faster.
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