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doesn't creep usually create peak torque? unless you dropped timing an insane amount or something weird
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No it doesn't.
Most of my stock motor builds creep up to 17 or 18 psi at redline intentionally using ebc and peak torque is still below 5000rpm like everyone else's. Last night I spent close to an hour pulling torque out of the 4500rpm area of a VVT turbo NA, which made 280rwhp, because that's where peak torque waseven with 100% wastegate Duty Cycle from 5500rpm onwards. We had to use VVT, timing and boost to pull that 4500rpm peak out of the tune, because VE. Dann |
creep using ebc? so it's intentional?
if you're inentionally shutting the wastegate up top to create more boost that's not the same as creep. the only cars I've seen creep to redline are hondas that have insane VE to begin with. maybe I'm wrong |
The engines torque output doesnt give a shit if its creep due to a low flowing wastegate port or due to a flapper being intentionally closed with EBC.
Yeah Im creating creep intentionally. The above example is a built engine, raced with a 5 speed, so we are using what is effectively creep to keep torque flat as possible but below a threshold. Even using a huge amount of creep torque peak is still in the normal spot and this is literally a good thing for performance, and not a bad thing for reliability, unless you have some issue like a fuel system that cant keep up or a lead foot and no driver skills. Dann |
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Originally Posted by nitrodann
(Post 1213342)
The engines torque output doesnt give a shit if its creep due to a low flowing wastegate port or due to a flapper being intentionally closed with EBC.
Yeah Im creating creep intentionally. The above example is a built engine, raced with a 5 speed, so we are using what is effectively creep to keep torque flat as possible but below a threshold. Even using a huge amount of creep torque peak is still in the normal spot and this is literally a good thing for performance, and not a bad thing for reliability, unless you have some issue like a fuel system that cant keep up or a lead foot and no driver skills. Dann When I ran the 6758 on just the 7psi spring pressure, it peaked at 12psi at peak power and tapered off from there. |
My point is who cares and why do they care.
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Originally Posted by nitrodann
(Post 1213342)
The engines torque output doesnt give a shit if its creep due to a low flowing wastegate port or due to a flapper being intentionally closed with EBC.
Yeah Im creating creep intentionally. The above example is a built engine, raced with a 5 speed, so we are using what is effectively creep to keep torque flat as possible but below a threshold. Even using a huge amount of creep torque peak is still in the normal spot and this is literally a good thing for performance, and not a bad thing for reliability, unless you have some issue like a fuel system that cant keep up or a lead foot and no driver skills. Dann creep is what happens when you can't control it, and it usually happens at peak torqure, because boost usually creates torque. "intentional creep", is not creep. it's just boost control basically what Leafy said. you're missing the point |
What is the point and why.
Seriously, spell the point out and justify it. |
lolol
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In Australia do the turbos spin the opposite direction?
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After doing dozens of tunes on cars where we need to limit torque for engine and or gearbox reliability, the only way that 'boost creep is bad because boost makes torque' could possibly make sense in this context is if you hadnt calculated a creeping cars torque across the area where it creeps during dyno tuning.
Im putting that to the non believers, and Im asking them to please dispute it. Dann |
Originally Posted by Corky Bell
(Post 1212976)
BH2dKeith,
No A/O for you until the cast manifold is in my hands. The pattern has been at the foundry long enough to expect castings within a couple weeks. Your turbo will need a few mods. You or me? If you do it, you will do it as I suggest. I will be glad to fix it up, nc. What fuel system are you using? Need EGR? Sorry about no Christmas card. It was just a bigger risk than I was willing to take. Hang loose, you are at the top of the list. I'll need to figure out which list that was. corky What needs to be done to the turbo to make it fit? Swap exhaust housing to a conventional one instead of the V-band? If so, I can handle that myself if parts are supplied. You had me re-clock the compressor housing and grind a bit on the compressor housing to get it to fit under the old tubular manifold, so I can handle re-clocking of the compressor housing also. If it is more complicated than that, I can send it your direction. I have an upgraded fuel pump, 1000cc injectors Megasquirt3 and am running E85. No EGR on my setup. Probably on top of your shit list right now :) If all of this works out, you will end up on my Christmas card list. Keith |
Originally Posted by nitrodann
(Post 1212993)
Seriously, why do we give a fuck if we get 5psi of creep past peak torque?
Keith |
I'm sorry why is there a 'goal boost' ?
Dann |
because there is such a thing as stock rods
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Oh I see.
And a measure of restriction at a given flowrate as opposed to torque is what we use to protect them. Now I understand! |
You're trying real hard. And I'm seeing right through it.
Yes, none of us know the difference between pressure and torque. We're all just stupid 'Muricans with rightside-up dyno plots. |
Seeing through it. Cite your reasons for being scared of boost creep. For crying out loud, Ive dyno'd this shit enough times to have no reasons myself.
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Someone should probably explain the difference between boost overshoot and boost creep. I'm pretty sure Dann is referring to creep (boost rises with RPM regardless of wastegate spring pressure), while everyone else is referring to overshoot (boost rises rapidly past the wastegate spring pressure which creates torque spikes that can damage stock engines).
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Thats correct.
Ive never seen overshoot on an MX5 with a T2x turbo or EFR using competent boost control, and CERTAINLY not with only the wastegate can for boost control. Dann |
Originally Posted by nitrodann
(Post 1213423)
Thats correct.
Ive never seen overshoot on an MX5 with a T2x turbo or EFR using competent boost control, and CERTAINLY not with only the wastegate can for boost control. Dann
Originally Posted by Savington
(Post 1213420)
Someone should probably explain the difference between boost overshoot and boost creep. I'm pretty sure Dann is referring to creep (boost rises with RPM regardless of wastegate spring pressure), while everyone else is referring to overshoot (boost rises rapidly past the wastegate spring pressure which creates torque spikes that can damage stock engines).
let me google that for you Dann http://lmgtfy.com/?q=what+is+boost+creep |
also see my buddy's fastivab25mr (or whatever his sn is) 300whp BP with stock rods that ejected them with ewg and only a can for boost control.
haven't seen much? tune more BP's PS: my buddy's rods all ejected PAST peak torque. that should blow your mind |
Reread what sav wrote, retard.
You failed at being a smartass. |
Originally Posted by 18psi
(Post 1213431)
see keiths build thread because I sure as heck am not about to post dozens of links to prove what we've all already known since 1995
e: This thread is basically a clusterfuck of nomenclature. Boost creep (boost rises with RPM, max boost at/near max power) doesn't put any additional stress on rods if it doesn't move the torque peak up. Uncontrolled creep is still not desirable because you can outrun the fuel injectors and it generally means the wastegate setup is pretty piss-poor. Boost overshoot (boost immediately rises beyond the desired level, max boost at/near max torque) is seriously undesirable in all cases and, by definition, is never induced on purpose. Most of you are talking about overshoot, but saying "creep". Dann is talking about creep as I've defined it. Can we get back to talking about how kludgy exhaust restrictors are now? |
Originally Posted by nitrodann
(Post 1213351)
What is the point and why.
Seriously, spell the point out and justify it. |
Originally Posted by nitrodann
(Post 1213458)
Reread what sav wrote, retard.
You failed at being a smartass. Are you back to neg propping every single one of my posts again? Is it that time of the month for you again?
Originally Posted by Savington
(Post 1213460)
You should probably post a link, because from where I'm sitting you sound like someone who doesn't actually understand the topic you're attempting to talk about.
:bowrofl: |
fuck all your strawman semantics arguments. That includes you vlad.
this is what we are discussing:
Originally Posted by nitrodann
Seriously, why do we give a fuck if we get 5psi of creep past peak torque?
If its past peak torque then its not putting any more stress on any components than peak torque already did. Which is why its called -peak- torque. Nitro's theory is that peak torque on a dyno plot is the peak load of an engine's conponents, so he tunes his cars to increase boost after peak torque to keep the torque output flat to redline. talk about that. |
But bro, he's tuned so many cars.
..and set so many records:laugh: |
Originally Posted by Braineack
(Post 1213503)
talk about that.
will not fit into brain because literally nothing past peak load matters. nothing bro. nothing. no stress on the components, just run ALLOFIT on an upsidedown dyno and your stock rods are fine |
Originally Posted by Braineack
(Post 1213503)
Nitro's theory is that peak torque on a dyno plot is the peak load of an engine's conponents, so he tunes his cars to increase boost after peak torque to keep the torque output flat to redline.
talk about that. |
in regards to tensile or total inertial loads, yes. total compression or power loads, no.
if you're inducing "creep" to maintain peak torque to redline, you're putting more load/stress on the rods the greater the rpm. |
More tensile load/stress, yes, but not more than a stock motor can handle (unless you rev it past 7k, which nobody has suggested). The compression load is what the stock rods care about, and the peak compression load happens at peak torque.
IOW, if the motor copes with 230wtq at 4000rpm, is 210wtq at 7000rpm going to break it? I think not. |
i dunno, i suppose. way to ruin it.
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Originally Posted by 18psi
(Post 1213499)
Are you back to being a complete and utter child and lashing out again?
Are you back to neg propping every single one of my posts again? Is it that time of the month for you again? Dann |
Originally Posted by Braineack
(Post 1213650)
i dunno, i suppose. way to ruin it.
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My dad did always tell me: "never let the truth ruin a good story"
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Nitro, Hang in there.
Vbad, ??//?????///??? 2D: You need V clamp? I Make V clamp. A/O can do both. 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. It appears nitro has figured this out, its just hard to get past the accent. Subject for the next thread: In what month of the year do the Aussies drink the least amount of Tequila? corky |
Originally Posted by Savington
(Post 1213638)
More tensile load/stress, yes, but not more than a stock motor can handle (unless you rev it past 7k, which nobody has suggested). The compression load is what the stock rods care about, and the peak compression load happens at peak torque.
IOW, if the motor copes with 230wtq at 4000rpm, is 210wtq at 7000rpm going to break it? I think not. In terms of compressive loads, 230wtq at 4000 vs 230wtq at 7000 is always going to be harder on the rods, because they have to endure that compressive load for nearly twice the amount of time. |
Originally Posted by Mobius
(Post 1213745)
Andrew r smart and understand physics.
In terms of compressive loads, 230wtq at 4000 vs 230wtq at 7000 is always going to be harder on the rods, because they have to endure that compressive load for nearly twice the amount of time. |
Originally Posted by Savington
(Post 1213671)
I like you because you never let the truth get in the way of a good internet pissing match :giggle:
:brain: I haven't really read up on loads in a quite a while--it's probably been over 10 years. I was thinking that if you added boost to redline and since tensile load is a function of rpm^2 that the loads would significantly increase as you reach redline, compared to if you held it steady. But that was wrong because that extra boost doesn't really factor into those loads and any increase in boost is really just making up for the loss of combustion pressure due to the speed of the explosions relative to the crank angle and all that business. Plus I really just wanted to argue about something. it takes a brave/strong man to admit he was wrong--remember that. |
Originally Posted by Corky Bell
(Post 1213728)
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. |
No no, my MX6 makes 1,900,000hp at 3800rpms.
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It doesn't say Power = HP
it says Power = P x L x A x N |
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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Originally Posted by Braineack
(Post 1213831)
It doesn't say Power = HP
it says Power = P x L x A x N
Originally Posted by DNMakinson
(Post 1213835)
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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Originally Posted by nitrodann
(Post 1213409)
I'm sorry why is there a 'goal boost' ?
Dann
Originally Posted by 18psi
(Post 1213410)
because there is such a thing as stock rods
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 |
Originally Posted by Corky Bell
(Post 1213728)
2D: You need V clamp? I Make V clamp. A/O can do both. corky 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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Originally Posted by Twodoor
(Post 1214097)
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 fuck 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. https://www.miataturbo.net/attachmen...ine=1426136068 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. https://www.miataturbo.net/attachmen...ine=1426136068 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 |
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 |
Originally Posted by Mobius
(Post 1213745)
...In terms of compressive loads, 230wtq at 4000 vs 230wtq at 7000 is always going to be harder on the rods, because they have to endure that compressive load for nearly twice the amount of time.
But in simple terms, for a 4 stroke engine, any given cylinder is going to spend 1/4th of it's time on the power stroke, 1/4th on compression, etc. |
Also Dan has a lot of good points, and I think you guys are all arguing over semantics/terms. How about instead of a pissing contest, let's be civil and talk about how to make miata's go faster and keep them reliable?
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Brain trolled Dann, and I jumped in, Dann got his panties in a wad as always and went off on me, as always, while brain stepped back and laughed at his successful troll.
I can't believe I have to spell it out for you guys. :fael: |
Originally Posted by patsmx5
(Post 1214884)
??? I don't get this part. Which is worse? And why? I get number of cycles is higher at higher RPM, that is obvious.
But in simple terms, for a 4 stroke engine, any given cylinder is going to spend 1/4th of it's time on the power stroke, 1/4th on compression, etc. 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 |
Originally Posted by Twodoor
(Post 1214903)
....
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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You want me to post the screenshot of the conversation me and Scott were having laughing at you on G-chat?
Or you wanna cry some more? hurr durr |
I feel that it would be necessary for anyone but you and Scott to believe what you are saying.
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I dont even know what this thread is about.
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Originally Posted by 18psi
(Post 1214901)
Brain trolled Dann, and I jumped in, Dann got his panties in a wad as always and went off on me, as always, while brain stepped back and laughed at his successful troll.
I can't believe I have to spell it out for you guys. :fael: |
no i actually made errors in my argument.
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