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 8604 Posts Member #: 573 Formerly Axel Podland |
19th Jul, 2007 at 04:57:52pm
On 19th of Jul, 2007 at 04:52pm matty said:
Just a quick novice question..What kind of accuracy do you get with these formulaes + or - how many BHP? The two pdf files attached above are based on known, believable dyno results and are within about 5%. It is all based on the science posted on the Garrett web site, so should be good. It's all based on R and Gamma. I can explain futher if you are interested! Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
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 9258 Posts Member #: 123 Post Whore Betwix Harrogate and York |
19th Jul, 2007 at 05:22:10pm
On 19th of Jul, 2007 at 04:44pm Axel said:
On 19th of Jul, 2007 at 04:30pm robert said:
On 19th of Jul, 2007 at 02:51pm Axel said:
On 19th of Jul, 2007 at 02:24pm robert said:
running 9.5 psi and 150 bhp squirrel software,stepping up ve till i get to my bhp/psi level. crude software ,but interesting -------------------------------------------------------------------------------- Engine RPM: 1000 1500 2250 3000 4800 6600 6750 6900 Vol Efficency: 88 89 89 89 93 96 92 87 Intake Temp: 64 65 73 80 92 104 104 104 Expected Boost (psi): 0 1 5.4 9.8 9.8 9.8 9.8 9.8 Pressure Ratio: 1 1.1 1.4 1.7 1.7 1.7 1.7 1.7 Airflow (lb/min): 1.5 2.5 4.7 7.5 12.2 16.5 16.5 16.1 Airflow (cfm): 22 36 68 108 176 239 240 233 Airflow (m^3/min): 0.63 1.01 1.91 3.07 4.99 6.77 6.79 6.6 Airflow (m^3/sec): 0.01 0.017 0.032 0.051 0.083 0.113 0.113 0.11 Airflow (kg/sec): 0.012 0.019 0.035 0.056 0.092 0.125 0.125 You are using a high VE to compensate for the high inlet temp. Allowing for an intercooler and bringing the VE down will give you the same answers. thats degrees f axel Makes even less sense then. Inlet air at 40 deg C and a 1.7:1 PR and 96% VE should give far more than 150hp! EDIT: calculated 188hp at those figures. Are you still putting in 15psi Axel? robert is only running 9.5. Fastest 998 mini in the world? 13.05 1/4 mile 106mph
On 2nd Jan, 2013 fastcarl said:
the design shows a distinct lack of imagination, talk about starting off with a clean sheet of paper, then not bothering to fucking draw on it,lol On 20th Apr, 2012 Paul S said:
I'm mainly concerned about swirl in the runners caused by the tangential entry. |
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8604 Posts Member #: 573 Formerly Axel Podland |
19th Jul, 2007 at 05:24:22pm
Nope, I've used 650 Kpag, about 9.5 psi. Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
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 1497 Posts Member #: 100 Parisien Turbo Expert Paris\' suburb |
20th Jul, 2007 at 06:18:07pm
a pince of pepper on that :
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8604 Posts Member #: 573 Formerly Axel Podland |
20th Jul, 2007 at 06:46:46pm
Well, one thing is clear - we don't agree Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
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1497 Posts Member #: 100 Parisien Turbo Expert Paris\' suburb |
23rd Jul, 2007 at 02:44:09pm
nothing new, just that an aserie haven't a bsfc at 0.41, the 0.55 is a little high but conservative for a turboed pushrod engine at max power,but this a give a safe side on maps, the truth certainly between these, about 90 ve and 0.51 bsfc |
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8604 Posts Member #: 573 Formerly Axel Podland |
20th Aug, 2007 at 03:19:06pm
This issue still needs to be resolved.
Edited by Paul S on 20th Aug, 2007. Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
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5795 Posts Member #: 80 AFRacing LTD Newbury, Berks |
20th Aug, 2007 at 04:07:25pm
Does that answer the question?
AlexF |
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8604 Posts Member #: 573 Formerly Axel Podland |
20th Aug, 2007 at 04:20:45pm
On 20th of Aug, 2007 at 04:07pm AlexF2003 said:
Does that answer the question? Alex No. Best estimate of VE is somewhere between 82% and 95% ! BSFC is somewhere between 0.41 and 0.55 lb/hp/hr. We need to do better. Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
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5795 Posts Member #: 80 AFRacing LTD Newbury, Berks |
20th Aug, 2007 at 04:28:41pm
How?
AlexF |
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8604 Posts Member #: 573 Formerly Axel Podland |
20th Aug, 2007 at 04:36:23pm
On 20th of Aug, 2007 at 04:28pm AlexF2003 said:
How? There must be a way this can be calculated or measured..... Alex You need some sophisticated kit to measure the variables to calculate it, otherwise it is a guess. Engine dyno with fuel and air flow metering would do it. Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
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Forum Mod 10980 Posts Member #: 17 ***16*** SouthPark, Colorado |
20th Aug, 2007 at 05:24:15pm
On 20th of Aug, 2007 at 03:19pm Axel said:
This issue still needs to be resolved. Dave and I advocate using a VE of 82%. Robert and Fab are using 95% ish. We are all agreeing on the final output figures, but using different BSFC. This is easy to conclude. 1) Axel and me are right 2) Rob and Fab are wrong LOL TBH guys - I'm a little lost much over how we can confirm this. None of us has access to any of this stuff needed. I guess if we carry on doing what we feel is right, then that is all we can do - unless of course, someone HAS a dyno (I've better things to invest money into sadly - like a mortgage)!!! The engines I've provided input into compressors for have come out pretty much as i predicted however. I am interested in how we can say a REAL factual figure however, as the camshaft is the key element (surely) that will ultimately dictate engine VE especially as baseline boost increases... I guess dyno's and simply trying different compressors (ouch $$$) and cam timings (ouch$$$ and ouch hrs) will reveal what the engine needs to make the beans? On 17th Nov, 2014 Tom Fenton said:
Sorry to say My Herpes are no better Ready to feel Ancient ??? This is 26 years old as of 2022 https://youtu.be/YQQokcoOzeY |
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8604 Posts Member #: 573 Formerly Axel Podland |
20th Aug, 2007 at 05:33:10pm
I think the the VE in the low eighties is about right.
Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
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Forum Mod 10980 Posts Member #: 17 ***16*** SouthPark, Colorado |
20th Aug, 2007 at 05:44:06pm
ah - I'd not even thought about the inlets; I was just thinking generically about engines and how we could work this out with what we have available.
On 17th Nov, 2014 Tom Fenton said:
Sorry to say My Herpes are no better Ready to feel Ancient ??? This is 26 years old as of 2022 https://youtu.be/YQQokcoOzeY |
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