The Resurrection of "The ACCUSER"
- Thread starter Bad Company
- Start date
If it helps, I have a 50% ceramic tint on my windshield, and it is fine with my regular glasses (progressive tint) but with my prescription sunglasses I cannot see the HUD. I don't normally drive with those prescription sunglasses so I'm not bothered by it.
After talking to my installer I have decided to follow your advice. I'm going with 70% tint on the windshield, which according to the manufacturer's website, XPEL Prime XR Plus this allows 67% of the light through while reducing 92% of the infrared heat absorption and blocking 99% of the UV rays entering the interior of the truck. This should keep the inside of the truck much cooler while sitting outside in the sunlight. Thank you for pointing me in the right direction.
I seriously doubt 1500 SAE on a DJ unless you crank that 4.9 over mid 20s for boost. Now answer my first question in regards to parasitic loss. My time here will never be worn as I own 694 Cobra and his whole crew at this point. PS: naming your car after the devil. Terrible idea
Stop acting like Joe Biden
And again.
A 4" upper with a 10% overdrive lower equals how much CFM at 7500 engine RPM with a 4.9Liter supercharger?
If you move a large amount of CFM in airflow boost what effects will this do to boost?
Boost is nothing more than..........what?????
You evident can't comprehend what you are reading. Why am I saying this? You evidently didn't read my first post in this thread thoroughly. I also explained that the Accuser is someone accusing someone in a court of law of fraud
Interesting
1. It depends on the specific compressor and also if said compressor suffers from any inlet restriction (as rear feed/side entrance PD superchargers normally do).
I haven't seen much in the way of KB 4.9 air flow data.
How many CFM are you expecting from a 4.9L supercharger with a 4" upper/10% OD lower @ 7500 rpm? What inlet/throttle body setup do you expect to see that CFM with?
2. If all variables remain totally equal then a decrease in supercharger output CFM will result in less boost and and increase in output CFM will result in a more boost.
3. Airflow restriction
4. From what I'm reading he's asking you to support the rationale that the ~200 HP gain observed by Van was solely from a reduction in parasitic loss from moving to a larger supercharger.
I too find this conclusion dubious without a full dyno graph and a full boost curve to confirm it.
Yes both dyno pulls saw a peak boost reading of 25 psi but were they both making 25 psi @ 7000 rpm (or whatever RPM peak HP occurred)?
My suspicion (without knowing all of the details) is the smaller supercharger most likely suffered from a inlet restriction of some sort and most likely experienced a boost drop through the dyno pull.
To do the math on the CFM output of the test done with BIRDDOCS car the CFM output of both the 4.2L and the 4.7L with the different pulley combinations are within 50 CFM of each other at 7000 engine RPM. The 4.2L with a ATI 15% overdrive lower and a 3.5" upper has the potential CFM output of 2408.74 CFM at 7000 engine RPM. The 4.7L with the ATI 15% overdrive lower and a 4" upper has the potential CFM output of 2358.56 CFM at 7000 engine RPM. The 4.7L supercharger is actually moving less air than the 4.2L with the pulley combinations stated in the test results.
The ATI Super Damper 15% overdrive pulley is 8.12" in diameter.
The drive ratios for each supercharger pulley combination are
8.12 divided by 3.5 = 2.32 pulley drive ratio for the 4.2L
8.12 divided by 4 = 2.03 pulley drive ratio for the 4.7L
supercharger speeds at 7000 engine RPM is
4.2L = 2.32 x 7000 = 16240 supercharger RPM
4.7L = 2.03 x 7000 = 14210 supercharger RPM
Now for each supercharger one rotation of the supercharger moves the amount in liters of air corresponding to its size
4.2L x 16240 SC RPM = 68208L per minute of airflow = 2408.7427 CFM
4.7L x 14210 SC RPM = 66787L per minute of airflow = 2358.5606 CFM
To convert Liter per minute to CFM you divide by 0.035314684921034435
The 4.7L SC is actually moving less air than the 4.2L SC in this comparison and pulley ratios.
Each supercharger use the exact same inlet elbow from KB. The 4.7L has a 1/2"(12.7mm) longer compressor pack and housing over the 4.2L, all of the other dimensions are the same so that each supercharger uses the same inlet elbow, front drive assembly and bearing housings both front and at the rear. So the inlet elbow for each supercharger has the same restriction at the same CFM airflow output of each supercharger. The rear bearing structures are the same, so the rear bearing support housings are the same so as not to change the area of the inlet to each supercharger compressor pack to cause a difference in airflow in this area of the superchargers.
The test was done using the same KB 168mm mono-blade throttle body from the 4.2L being installed on the 4.7L for the same airflow restrictions of the TB. The TB is flow rated by KB at 2150CFM. The same air filter, air filter tube and MAF sensor was used between the two tests.
As you can see the 168mm mono-blade TB is now being the inlet restriction source for each supercharger according to KB's flow rating of the TB.
Now to answer your question about the 4.9L supercharger at 7500 engine RPM
First thing is everyone will assume that the compressor pack and housing of the 4.9L is larger than the 4.7L..........it is not. The 4.9L compressor pack and housing is the exactly the same size as a 4.7L, the compressor pack of the 4.9L has been coated to increase the efficiency. It is a coated 4.7L. The parasitic Hp differences to rotate each should be very similar to each other since we are dealing with the same rotating mass of both the 4.7L and the 4.9L.
Now the 4.9L with a pulley drive ratio
pulley drive ratio for the ATI damper 10% lower overdrive and a 4" upper is
7.81 divided by 4 = 1.9525
1.9525 x 7500 engine RPM = 14643.75 SC RPM
4.9L x 14643.75 SC RPM = 71754.375L per minute of airflow = 2533.9818 CFM
Now my 4.9L @ 7500 engine RPM is moving 175.4212 CFM more air than the 4.7L on BIRDDOCS combination, but I'm turning my engine 500 more
RPM. So let's compare them at 7000 RPM
1.9525 pulley drive ratio x 7000 = 13667.5 SC RPM
13667.5 SC RPM x 4.9L = 66970.75 liter per minute = 2365.0496 CFM
Let's put this in one paragraph for easy comparisons of each supercharger with the different pulley drive ratios listed above at the same 7000 engine RPM.
4.2L = 2408.7427 CFM at 7000 RPM
4.7L = 2358.5606 CFM at 7000 RPM
4.9L = 2365.0496 CFM at 7000 RPM
As you can see the CFM output of each combination is fairly close to each other. It takes a little time to do the math to find the best pulley combinations to achieve the results. Hopefully with the CFM outputs being very similar the differences are going to be in the parasitic loses to turn the SCs resulting in more Hp at the tires with the combination of the 4.9L. Now the problem is this, will the TB cause a reduction in this possible gain? We will have to wait and see for the dyno results. The other problem will of course be the fact the results will NOT be on the same dyno on the same day with the same atmospheric conditions.
Why do I think I can get to 1500 whereas Mark's car did 1417. My engine has very different modifications done to the cylinder heads, intake manifold and exhaust system to reduce restrictions significantly over Mark's car at the time of the test done that I referred to earlier in this thread. I believe those restriction differences along with the parasitic differences in turning the 4.9L slower will add up to a 83Hp gain. My only concern is the TB restriction as engine RPM increases above 7000 RPM.
The ATI Super Damper 15% overdrive pulley is 8.12" in diameter.
The drive ratios for each supercharger pulley combination are
8.12 divided by 3.5 = 2.32 pulley drive ratio for the 4.2L
8.12 divided by 4 = 2.03 pulley drive ratio for the 4.7L
supercharger speeds at 7000 engine RPM is
4.2L = 2.32 x 7000 = 16240 supercharger RPM
4.7L = 2.03 x 7000 = 14210 supercharger RPM
Now for each supercharger one rotation of the supercharger moves the amount in liters of air corresponding to its size
4.2L x 16240 SC RPM = 68208L per minute of airflow = 2408.7427 CFM
4.7L x 14210 SC RPM = 66787L per minute of airflow = 2358.5606 CFM
To convert Liter per minute to CFM you divide by 0.035314684921034435
The 4.7L SC is actually moving less air than the 4.2L SC in this comparison and pulley ratios.
Each supercharger use the exact same inlet elbow from KB. The 4.7L has a 1/2"(12.7mm) longer compressor pack and housing over the 4.2L, all of the other dimensions are the same so that each supercharger uses the same inlet elbow, front drive assembly and bearing housings both front and at the rear. So the inlet elbow for each supercharger has the same restriction at the same CFM airflow output of each supercharger. The rear bearing structures are the same, so the rear bearing support housings are the same so as not to change the area of the inlet to each supercharger compressor pack to cause a difference in airflow in this area of the superchargers.
The test was done using the same KB 168mm mono-blade throttle body from the 4.2L being installed on the 4.7L for the same airflow restrictions of the TB. The TB is flow rated by KB at 2150CFM. The same air filter, air filter tube and MAF sensor was used between the two tests.
As you can see the 168mm mono-blade TB is now being the inlet restriction source for each supercharger according to KB's flow rating of the TB.
Now to answer your question about the 4.9L supercharger at 7500 engine RPM
First thing is everyone will assume that the compressor pack and housing of the 4.9L is larger than the 4.7L..........it is not. The 4.9L compressor pack and housing is the exactly the same size as a 4.7L, the compressor pack of the 4.9L has been coated to increase the efficiency. It is a coated 4.7L. The parasitic Hp differences to rotate each should be very similar to each other since we are dealing with the same rotating mass of both the 4.7L and the 4.9L.
Now the 4.9L with a pulley drive ratio
pulley drive ratio for the ATI damper 10% lower overdrive and a 4" upper is
7.81 divided by 4 = 1.9525
1.9525 x 7500 engine RPM = 14643.75 SC RPM
4.9L x 14643.75 SC RPM = 71754.375L per minute of airflow = 2533.9818 CFM
Now my 4.9L @ 7500 engine RPM is moving 175.4212 CFM more air than the 4.7L on BIRDDOCS combination, but I'm turning my engine 500 more
RPM. So let's compare them at 7000 RPM
1.9525 pulley drive ratio x 7000 = 13667.5 SC RPM
13667.5 SC RPM x 4.9L = 66970.75 liter per minute = 2365.0496 CFM
Let's put this in one paragraph for easy comparisons of each supercharger with the different pulley drive ratios listed above at the same 7000 engine RPM.
4.2L = 2408.7427 CFM at 7000 RPM
4.7L = 2358.5606 CFM at 7000 RPM
4.9L = 2365.0496 CFM at 7000 RPM
As you can see the CFM output of each combination is fairly close to each other. It takes a little time to do the math to find the best pulley combinations to achieve the results. Hopefully with the CFM outputs being very similar the differences are going to be in the parasitic loses to turn the SCs resulting in more Hp at the tires with the combination of the 4.9L. Now the problem is this, will the TB cause a reduction in this possible gain? We will have to wait and see for the dyno results. The other problem will of course be the fact the results will NOT be on the same dyno on the same day with the same atmospheric conditions.
Why do I think I can get to 1500 whereas Mark's car did 1417. My engine has very different modifications done to the cylinder heads, intake manifold and exhaust system to reduce restrictions significantly over Mark's car at the time of the test done that I referred to earlier in this thread. I believe those restriction differences along with the parasitic differences in turning the 4.9L slower will add up to a 83Hp gain. My only concern is the TB restriction as engine RPM increases above 7000 RPM.
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