Fantastic numbers!! :D
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OP nice numbers, how do you like the turbo? How is spool?
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Originally Posted by ray_sir_6
(Post 313458)
Conservative? I am running a smaller turbo and making 190whp at 5.5psi. I am still tuned very conservatively as well. The more I see outputs from MS cars, the less I like it.
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Originally Posted by Toddcod
(Post 313743)
I have a crappy map at 6psi. Lets run them and see the differance. I'm going to laugh if my crappy map and MS leaves your car in the dust.
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It would be awesome if you guys posted up logs of the runs along with the results of AEM vs MS.
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Well, viewed the logs, boost sits between .39 and .43 BAR. So that is approx. 5.7psi to 6.2 psi. That was WG only. We have now hooked up the boost solenoid, and are running .061 BAR (8.8psi).
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Originally Posted by ray_sir_6
(Post 313810)
Well, viewed the logs, boost sits between .39 and .43 BAR. So that is approx. 5.7psi to 6.2 psi. That was WG only. We have now hooked up the boost solenoid, and are running .061 BAR (8.8psi).
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I'm calling bullshit on all of it, from top to bottom.
For example, the OP says he's making "12.5 psi 1.6 230rwhp". Now, does this really pass the common sense test. Let's try it and see... 230rwh * 1.17 = 269 crank hp. 12.5 psi + 14.7 psi (atmospheric pressure) = 27.2 psi absolute pressure. Now let's say a NA 1.6 liter Miata makes 116 crank hp at 13.7 psi absolute pressure. The 1 psi below atmospheric is to account for losses within the intake system, and neglects any gains in either the intake or exhaust for pressure waves. In other words, it's a reasonably conservative assumption. Now with the OP's 27.2 psi (12.5 psi boost) one would expect an increase of: (27.2 psi / 13.7 psi) * 116 hp = 230.3 hp. Again, this would be a generous figure unless significant other improvements were made which would boost the volumetric factor beyond the 95% already assumed. So where does the extra 39 hp, which is a 17% increase, come from? I'll tell you where it comes from - marketing. Let's try this again with the 190 hp example at 5.5 psi.... 190rwh * 1.17 = 222 crank hp. 5.5 psi + 14.7 psi (atmospheric pressure) = 20.2 psi absolute pressure. Now with the OP's 20.2 psi (5.5 psi boost) one would expect an increase of: (20.2 psi / 13.7 psi) * 116 hp = 171.3 crank hp. So again, where does the 51 hp, an even more incredible 30% increase come from? Elesjuan said it best when he said, "Fantastic numbers!!", though I'm not sure he and I are using fantastic in the same way. I don't give a shit what kind of exhaust system you hang on there, or what kind of turbo's pumping your air, the horsepower you generate is essentially directly related to the amount of air and fuel that's pumped through your motor, and it doesn't take a brain gardener to run the simple calc's necessary to know if your dyno tech is blowing smoke up your ass to ensure you're happy with your mods and come back to him the next time you change something. The Brain said something to the effect that determining the level of boost needed, on paper, is nearly impossible and never correct. You might want to rethink that Brain. I'm beginning to think that determination the level of horsepower produced by any amount of boost using a BS dyno is nearly impossible and never correct. Case in point above. Well, I guess the HP and percentage gain claims are no worse than those made for fuel aligning magnets, vortex spinners, and fuel-air bubblers; it's just that those mods are relatively cheap. It's unfortunate that a development tool as valuable as a dyno is commonly "corrected" in a manner that makes it essentially useless to serious tuners unless they are in on the secret. |
i dont know... i think its very possible with 2860
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Originally Posted by UrbanSoot
(Post 313921)
i dont know... i think its very possible with 2860
And more explicitly, at a given temperature how is 5.5 psi boost from a GT2554R different than 5.5 psi boost from 2860? I already understand that depending on the volume delivery either of those turbos might be in a more efficient range and have a lower temperature, so one or the other might generate different horsepower values, but we're talking extreme cases not a comparison of two well chosen and designed turbo systems. |
is this a gt2860rs or a gt2860?
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Originally Posted by johndoe
(Post 313926)
is this a gt2860rs or a gt2860?
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Originally Posted by Thucydides
(Post 313932)
Does it matter?
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Originally Posted by Thucydides
(Post 313906)
I'm calling bullshit on all of it, from top to bottom.
For example, the OP says he's making "12.5 psi 1.6 230rwhp". Now, does this really pass the common sense test. Let's try it and see... 230rwh * 1.17 = 269 crank hp. 12.5 psi + 14.7 psi (atmospheric pressure) = 27.2 psi absolute pressure. Now let's say a NA 1.6 liter Miata makes 116 crank hp at 13.7 psi absolute pressure. The 1 psi below atmospheric is to account for losses within the intake system, and neglects any gains in either the intake or exhaust for pressure waves. In other words, it's a reasonably conservative assumption. Now with the OP's 27.2 psi (12.5 psi boost) one would expect an increase of: (27.2 psi / 13.7 psi) * 116 hp = 230.3 hp. Again, this would be a generous figure unless significant other improvements were made which would boost the volumetric factor beyond the 95% already assumed. So where does the extra 39 hp, which is a 17% increase, come from? I'll tell you where it comes from - marketing. Let's try this again with the 190 hp example at 5.5 psi.... 190rwh * 1.17 = 222 crank hp. 5.5 psi + 14.7 psi (atmospheric pressure) = 20.2 psi absolute pressure. Now with the OP's 20.2 psi (5.5 psi boost) one would expect an increase of: (20.2 psi / 13.7 psi) * 116 hp = 171.3 crank hp. So again, where does the 51 hp, an even more incredible 30% increase come from? Elesjuan said it best when he said, "Fantastic numbers!!", though I'm not sure he and I are using fantastic in the same way. I don't give a shit what kind of exhaust system you hang on there, or what kind of turbo's pumping your air, the horsepower you generate is essentially directly related to the amount of air and fuel that's pumped through your motor, and it doesn't take a brain gardener to run the simple calc's necessary to know if your dyno tech is blowing smoke up your ass to ensure you're happy with your mods and come back to him the next time you change something. The Brain said something to the effect that determining the level of boost needed, on paper, is nearly impossible and never correct. You might want to rethink that Brain. I'm beginning to think that determination the level of horsepower produced by any amount of boost using a BS dyno is nearly impossible and never correct. Case in point above. Well, I guess the HP and percentage gain claims are no worse than those made for fuel aligning magnets, vortex spinners, and fuel-air bubblers; it's just that those mods are relatively cheap. It's unfortunate that a development tool as valuable as a dyno is commonly "corrected" in a manner that makes it essentially useless to serious tuners unless they are in on the secret. Dynojets don't squew the numbers. You have to seriously try to get it to do a wrong correction, like have the temp/barometer sensor in a seperate area, so that you can control what temp/humidy, etc, it reads that could be changed to make the calculation different. Some shops do that, and that's why they are not certified by American Iron as an authorized dyno location. Where I work we are one of 2 in the DFW area that IS certified. They do random inspections and have a car that they take around to make sure they read the same on the 2 different dynos. I also WORK THERE, so he isn't trying to make me buy more, cause I pay cost, that's it. Also, if you look at the dynosheet, it says "Correction: STD" which is the LOWEST correction factor. Lots of dynos read different, but a Dynojet reads the same as another Dynojet. I took my last car to 2 shops, I got IDENTICAL figures from our dyno and ATS Racing's dyno. Both are Dynojets.
Originally Posted by Thucydides
(Post 313924)
Care to explain exactly how?
And more explicitly, how is 5.5 psi boost from a GT2554R different than 5.5 psi boost from 2860? http://www.turbobygarrett.com/turbob...1_3_comp_e.gif http://www.turbobygarrett.com/turbob...0-5_comp_e.gif |
of course it matters. You have someone like savington running 14+psi on a gt2554 making less power than someone like y8s who's only running 9.5 psi on a GT2876R
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Originally Posted by ray_sir_6
(Post 313944)
I really like how you simplified it where you don't have to include air flow, air temp, or exhaust restrictions in your equations. Gotta love people who think math is the answer to everything, yet can't include all the variables to account for what actually makes power in an engine.
air/fuel ratio, brake specific fuel consumption, intake manifold temperature, volumetric efficiency, engine rpms, engine displacement, pressure loss before the compressor, and pressure loss between the compressor and intake plenum Here's what it looks like for your 1.6 liter 269 hp motor motor: Airflow Required Input Parameter Units Value Notes H.P. Target 269 Air/Fuel Ratio 12 Brake Specific Fuel Consumption lb/(H.P.*hr) 0.55 Use 0.5 to 0.6 (or higher) Output Parameter Flow Rate lb/min 29.6 Manifold Pressure Required (Absolute) Input Flow Rate 29.59 Gas Constant - R 639.6 Intake Manifold Temperature Degrees F 130 Volumetric Efficiency 0.95 Use 0.95 to 0.99 for modern four-valve heads Engine RPM - N 6750 Engine Displacement (Vd) Liters 1.6 Muliplied by 61.02 in final formula to convert to cubic in. Output Parameter Manifold Pressure (Absolute) PSI 35.7 Boost Pressure Required Input Manifold Pressure (Absolute) PSI 35.7 Atmospheric Pressure PSI 14.7 Output Boost Pressure Required (gauge) PSI 21.0 Pressure Losses Input Manifold Pressure (Absolute) PSI 35.7 Estimated loss Comp. to Manifold PSI 2.5 Use 1 to 4 psi (very efficient to fairly restrictive) Output Compressor Discharge Pressure PSI 38.2 Input Pressure loss before Compressor PSI 1.5 Use 1 to 2 psi (very efficient to fairly restrictive) Atmospheric Pressure PSI 14.7 Output Compresser Inlet Pressure PSI 13.2 Output Pressure Ratio between Discharge and Inlet 2.89 Maximum B.H.P. Data for Use with Turbo Charts Pressure Ratio between Discharge and Inlet 2.89 Flow Rate lbs/min 29.6 Alternate R.P.M. Data for Use with Turbo Chargs Background Values H.P. Target 269 Boost Pressure Required PSI 21.0 Input New Engine R.P.M. 6750 Input Volumetric Efficiency % 0.95 Input Manifold Pressure (Absolute) PSI 35.7 Input Engine Displacement (Vd) Liters 1.6 Input Intake Manifold Temperature Degrees F 130 Input Gas Constant - R 639.6 Output Flow Rate at new rpm value lbs/min 29.6 Do you think that including those parameters would have 1) improved the explanation, or 2) changed the result. I can't answer the first for you, but I did check the second and the answer is no. A back of the envelope calculation and Garrett's calculation yield essentially the same result. Do you think for one moment that the folks at Garrett don't understand how their turbo chargers generate power in their customers motors? Think they might have left out any magic variables and lost 30% of their customers horse power; power you found in a Dynojet? I specifically used a back of the envelop approach (I was one told by a very smart fellow that if you can't explain a concept on the back of an envelope you don't understand what it is you're trying to explain, and neither will any one else) so that folks like you can point to a fault in my approach and say, ah ha!, there's the problem. Feel free to do so and ad whatever other variables you think necessary to prove your point. Complicated math doesn't mean it's better (E=MC^2), it often means it's merely less understandable. I could have made it even simpler, but then even your average 5th grader could have understood it and then where's the mystery? Oh shit, I can't help myself: Boost power = ((boost + atmospheric)/atmospheric))*stock HP Let's see how it compares with Garrett's analysis of the 21 psi boost 269 hp 1.6 liter motor: ((21+14.7)/14.7)*116 = 282. Damn, it's off by 4.7% Sure it's going to be off 4% or 5% (the price for not having 10,000 variables), but heck, that's way better than your megabucks dynojet.
Originally Posted by ray_sir_6
(Post 313944)
Also, if you look at the dynosheet, it says "Correction: STD" which is the LOWEST correction factor. Lots of dynos read different, but a Dynojet reads the same as another Dynojet. I took my last car to 2 shops, I got IDENTICAL figures from our dyno and ATS Racing's dyno. Both are Dynojets.
"Correction: STD"; just what the fuck does that mean? Just some variable they put in but don't bother to explain or quantify. Yeah, why would you want to know what their correction factor was anyhow? "It's our standard correction; it will make your car look good." Sure, let them put whatever the hell correction they want to in there as long as it's "STD" and the numbers look good. Wait, I want the LTD correction, or perhaps the HYPER correction; no I think I'll take the MEGA HYPER LTD correction with extra CHUCK NORRIS punching power.
Originally Posted by ray_sir_6
(Post 313944)
PSI doesn't means shit, AIR FLOW is what matters. A GT28 will FLOW MORE AIR at the same psi than a GT25.
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Erm, why wouldn't the OP's car make 230 RWHP at 12.5 psi? My little greddy made 247 at 14 psi. Sounds perfectly believable to me.
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Originally Posted by ray_sir_6
(Post 313944)
There is a reason they don't have an ACCURATE "Turbo Power Calculator" for you to download online. Cause it is NEVER that simple.
But let me make one thing perfectly clear. I'm not at all down on dynometers in general, or Dynojet's in particular. What bothers me is they won't simply tell you what they've measured; they always "correct" the results. The problem is that their correction factor may not accurately reflect the drive line differences in say a 4 cylinder stick shift Miata and a 7.5 liter diesel automatic pickup. The financial pressure is to make big numbers; nobody wants to know that their stock Miata only makes 85 hp on the dyno. They want to see 116, or with an air kit and exhaust, 130. "Ah sir, your miata makes 85 hp at the rear wheels" "I thought it was supposed to make 116". "Actually sir, your's isn't bad, I've seen plenty of 70 hp miatas out there" "You charged me $175 to tell me my miata makes less than the factory says it does; fuck you I'm never coming back". next customer: "What's my miata making" "Just one moment sir while I install the STD correction" "Yep, it's 136 hp." "Wow! I was only expecting 130" "Sir, that will be $175" "Thanks! I'll see you in a week after I've installed my Chuck Norris turbulatior". "See you next week". So they tell you what you expect, because that's easier than explaining why. This is how I ended up with a dumb oil pressure gauge on my '95; not because it was necessarily cheaper to install, but because it saved on calls to the dealer from worried owners. "My oil pressure gauge is always moving; why can't it make up it's mind? I've had it to the dealer sixteen times and they always tell me the same thing". "What's that sir". "That they're supposed to do that. Can you make it stop?" "Don't worry sir, we're working on a fucks, I mean a fix, now. It will be coming out in our '95 models". |
Originally Posted by kotomile
(Post 313984)
Erm, why wouldn't the OP's car make 230 RWHP at 12.5 psi? My little greddy made 247 at 14 psi. Sounds perfectly believable to me.
But really, the reason is that when the OP says he made 230 rwhp it means about 269 at the crank, and the numbers simply don't add up. The math is simple because the concepts are simple. There's no more to it than that. I suspect what is happening is that there's confusion between rear wheel and crank horsepower, and that the dyno guys are muddying the water by reading one and reporting the other. |
Originally Posted by Thucydides
(Post 313974)
I simplified the equation to make it accessible to the greatest number of people. Besides, the basic premise of my argument doesn't change when you include air temp, exhaust restrictions, etc. For my own understanding I use Garrett's approach which includes the following variables:
<something you copied from some online calculator> Do you think that including those parameters would have 1) improved the explanation, or 2) changed the result. I can't answer the first for you, but I did check the second and the answer is no. A back of the envelope calculation and Garrett's calculation yield essentially the same result. Do you think for one moment that the folks at Garrett don't understand how their turbo chargers generate power in their customers motors? Think they might have left out any magic variables and lost 30% of their customers horse power; power you found in a Dynojet? I specifically used a back of the envelop approach (I was one told by a very smart fellow that if you can't explain a concept on the back of an envelope you don't understand what it is you're trying to explain, and neither will any one else) so that folks like you can point to a fault in my approach and say, ah ha!, there's the problem. Feel free to do so and ad whatever other variables you think necessary to prove your point. Complicated math doesn't mean it's better (E=MC^2), it often means it's merely less understandable. I could have made it even simpler, but then even your average 5th grader could have understood it and then where's the mystery? Oh shit, I can't help myself: Boost power = ((boost + atmospheric)/atmospheric))*stock HP Sure it's going to be off 10% or 15% (the price for not having 10,000 variables), but heck, it's better than your megabucks dynojet. Amazing! So two Dynojet's, which came from the same company, were built by the same workers, from the same parts, operated in a similar matter, and using the same principals for measuring engine output, produce identical results. That doesn't mean either is accurate. "Correction: STD"; just what the fuck does that mean? Just some variable they put in but don't bother to explain or quantify. Yeah, why would you want to know what their correction factor was anyhow? "It's our standard correction; it will make your car look good." Sure, let them put whatever the hell correction they want to in there as long as it's "STD" and the numbers look good. Yeah, and a GT42R will flow 4x what a 28 will. Airflow doesn't mean shit if it's not related to pressure. They're completely and irrevocably related. Look at the efficiency charts and tell me you can eliminate the pressure axis. And hey, I've got a big room fan that moves tremendous volume but do you think it will make a good turbocharger? 12psi on a GT25 is not the same as 12psi on a GT28. Why? Cause one FLOWS MORE AIR. 10psi on a waterhose won't get you near the water you would get on 10psi from a fire hose. Yeah, you still get 10psi worth of water, but when your house is on fire, I bet you want the one that flows more. How can you not understand AIR FLOW and still want to be involved in this thread? Boost power = ((boost + atmospheric)/atmospheric))*stock HP HAHAHAHAAHA. 10-15% off? Maybe if you are running a GT25 or a GT28, but running a GT35, it's not gonna be even close. http://www.turbobygarrett.com/turbob...8_1_comp_e.gif The best way to determine the hp a turbo will support is to use the airflow. Where it says 30lb/min it will support approx. 300hp. So if you are running 18psi (2.25Bar if you want to look on the chart) you will make approx. 300hp. Using your formula, I can make 630hp on a Evo that makes 280hp stock. Only 330hp too much. It was a good try, but it failed soo hard. I love how you bash dynos, when even your expanded formula wouldn't be as accurate as a properly used dyno. Dyno's don't inflate the numbers, the people playing with them do. That's what makes Dynojets the standard, they use as little manual inputs as possible to keep them from getting incorrect numbers. They have formulas that WORK on dynos, cause they aren't trying to calculate for all the different parameters of internal combustion, they are only determining how much hp it takes to create current from spinning a know weight. Same thing an engine dyno does, but it hooks to the flywheel. Or we can just keep using your formulas to try and determine an estimate without knowing all the variables. We can always tear the motor apart and measure it, send the head off for flow testing, along with the the turbo, manifolds, TB, etc. Even then you can't 100% determine the output of the motor, cause there are far too many variables , IE VE, weight, oil used, etc. You can go thru all that, and you'll spend way more time and money to get within 3% of what the Dynojet dyno will show. STD - Standard Correction. That means it does the least amount of adjustments possible to the output. This is the one I use cause it is ALWAYS the lowest reading. SAE would add about 3-5whp, which is a formula that meets the requirements of the SAE. The numbers by Garrett are only the amount of airflow the turbo makes at a certain psi. It doesn't determine what the engine hp will be. That is done by the engine and the tune itself. Please go read a book or something. Get educated on what you are talking about before you reply. It will save me alot of time having to correct it. |
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