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Old 01-11-2010, 09:17 PM   #51
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Total, what effect did detuning the engine have on efficiency/longevity, if any?
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Old 01-12-2010, 10:44 AM   #52
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So I know Eaton makes the rotors for the TVS-series SCs out there, and I know twin screws are a different animal, altogether, but is there only one company that makes these rotors for other twin screw companies too, or does your European manufacturer make these for you only? I think I recall another twin screw company that made their own rotors, but I'll be darned if I ever read the whole story.

I also wanted to mention that I believe it's the current MM&FF that has the really good write-up on the 3.6 KB. It's a pretty good write-up and just gives an idea on the benefits of this new design. Also, the article I referrenced earlier was from 5.0 Mustang, from a few months ago. I did mention some things in the article that I questioned, however, I think it, too, is at least a good referrence, and shows another supercharger options we'll have for Camaro too.

Did I just admit I buy Mustang magazines?...
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Old 01-12-2010, 11:55 AM   #53
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[Check out this months issue of Muscle Mustangs and Fast Fords. They install one on a Super Snake with before and after Dyno pulls. Sounds like the 3.6 is the deal.
Both were tested at 23PSI, the 3.6 made 76 more RWHP. At 15 PSI, the 3.6 made 31 more RWHP.

This is from a forum post on teamshelby. Is this true? at the same psi the 3.6 will make noticealby more HP than the 2.8H?
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Old 01-12-2010, 12:58 PM   #54
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None whatsoever. Although excessive detuning can lead to certain ill effects, this is nowhere near that area. Keep in mind that forced induction (boost) is very very sensitive to spark. By just removing a couple degrees of spark at WOT is enough to eliminate any chances of failure.
Our WOT spark table on the base tune is 16*. Couple that with the poroper WOT fuel table, and there is no issue at all.

The reason this had to be done, was because the 2.8H on a Camaro already uses a MASSIVE 4" blower pulley in order to keep the boost at the proper level. We cant go any bigger.

Jim B and I were on the phone last night, and bustin up about a few things.. Imagine this.. If you put a 3.6 onto a STOCK Camaro, and tried to keep the boost level the 2.8H has (like the base kit), we would have to run a 5.75" blower pulley.. The blower pulley would be almost as large as the crank pulley..

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Total, what effect did detuning the engine have on efficiency/longevity, if any?
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Old 01-12-2010, 01:09 PM   #55
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This is why KB is beginning to love Camaro guys..

See, if you talk to a mustang guy, they want their cars to go as fast as possible. They dont sit there and complain about how much "Bling" it has, or wether or not the hood changes the aerodynamic affects of the car. Unfortunately, in other application of GM cars, they care more about how pretty the hood looks, or wether or not they add 2.1lbs of weight, and could care a less that the car now has 2 to 3 times the power.. We all feel that the new Camaro, and its owners will finally appreciate what the mustang guys have been enjoying for years.

The answer to your question is a little more difficult though. No, there is not only 1 company that makes twin screw rotors. That being said, KB doesnt divulge any more info than that. I can say that the rotors that KB has made for them are propriatary, and not avail for any other company, but other than that, its not something that is made avail. In the past, it was a different story, but a while back they broke away from the mass produced setups, and went private. A trained eye can see the differences in the head units, but most dont see.
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So I know Eaton makes the rotors for the TVS-series SCs out there, and I know twin screws are a different animal, altogether, but is there only one company that makes these rotors for other twin screw companies too, or does your European manufacturer make these for you only? I think I recall another twin screw company that made their own rotors, but I'll be darned if I ever read the whole story.

I also wanted to mention that I believe it's the current MM&FF that has the really good write-up on the 3.6 KB. It's a pretty good write-up and just gives an idea on the benefits of this new design. Also, the article I referrenced earlier was from 5.0 Mustang, from a few months ago. I did mention some things in the article that I questioned, however, I think it, too, is at least a good referrence, and shows another supercharger options we'll have for Camaro too.

Did I just admit I buy Mustang magazines?...
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Old 01-12-2010, 01:17 PM   #56
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All superchargers are in the game now. Let the blower games begin I personally like the top mount motors.
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Old 01-12-2010, 01:37 PM   #57
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Old 01-12-2010, 02:06 PM   #58
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Quote:
Originally Posted by ironpeddler View Post
[Check out this months issue of Muscle Mustangs and Fast Fords. They install one on a Super Snake with before and after Dyno pulls. Sounds like the 3.6 is the deal.
Both were tested at 23PSI, the 3.6 made 76 more RWHP. At 15 PSI, the 3.6 made 31 more RWHP.

This is from a forum post on teamshelby. Is this true? at the same psi the 3.6 will make noticealby more HP than the 2.8H?
That's the issue I'm talking about. It's a great article and I like what they've done in it for the most part. It's certainly something to think about. I can't recall off the top of my head, but I believe the gain was correct.

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Old 01-12-2010, 02:13 PM   #59
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Quote:
Originally Posted by Total_Perf_Eng View Post
None whatsoever. Although excessive detuning can lead to certain ill effects, this is nowhere near that area. Keep in mind that forced induction (boost) is very very sensitive to spark. By just removing a couple degrees of spark at WOT is enough to eliminate any chances of failure.
Our WOT spark table on the base tune is 16*. Couple that with the poroper WOT fuel table, and there is no issue at all.

The reason this had to be done, was because the 2.8H on a Camaro already uses a MASSIVE 4" blower pulley in order to keep the boost at the proper level. We cant go any bigger.

Jim B and I were on the phone last night, and bustin up about a few things.. Imagine this.. If you put a 3.6 onto a STOCK Camaro, and tried to keep the boost level the 2.8H has (like the base kit), we would have to run a 5.75" blower pulley.. The blower pulley would be almost as large as the crank pulley..
I'm curious why the gearing inside the head unit wasn't designed to compensate for this. It is funny, though. Who would've ever thought you'd have to reign in a supercharger because it's TOO powerful.

Quote:
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This is why KB is beginning to love Camaro guys..

See, if you talk to a mustang guy, they want their cars to go as fast as possible. They dont sit there and complain about how much "Bling" it has, or wether or not the hood changes the aerodynamic affects of the car. Unfortunately, in other application of GM cars, they care more about how pretty the hood looks, or wether or not they add 2.1lbs of weight, and could care a less that the car now has 2 to 3 times the power.. We all feel that the new Camaro, and its owners will finally appreciate what the mustang guys have been enjoying for years.
Flattery will get you nowhere....


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Old 01-12-2010, 02:46 PM   #60
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Good question..

Its just not possible. The main drive gear on the 2.8H is already almost 4" in diameter. Any larger and it would come out of the case. Plus, rotor timing on these blowers are critical. If memory serves me right, the clearence between rotors is something like .003". It takes a highly skilled KB tech to properly time the gears on these things. When they test them, they run them at like 17,500 rpms, for something like 15 straight seconds (No intercooler). Although that doesnt sound like much, the temp spikes are huge. Thats equivelent to running a full half mile at WOT/Redline. Those gears have to be perfectly in sync, or else your talking MASSIVE destruction.

Yeah, we were cracking up about it last night. The absolute lowest boost we could get out of a 3.6, and still keep a 4" pulley, is like 12psi. The difference between the 3.6 and 2.8 is freaking huge.
Quote:
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I'm curious why the gearing inside the head unit wasn't designed to compensate for this. It is funny, though. Who would've ever thought you'd have to reign in a supercharger because it's TOO powerful.


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Old 01-12-2010, 02:59 PM   #61
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Good question..

Its just not possible. The main drive gear on the 2.8H is already almost 4" in diameter. Any larger and it would come out of the case. Plus, rotor timing on these blowers are critical. If memory serves me right, the clearence between rotors is something like .003". It takes a highly skilled KB tech to properly time the gears on these things. When they test them, they run them at like 17,500 rpms, for something like 15 straight seconds (No intercooler). Although that doesnt sound like much, the temp spikes are huge. Thats equivelent to running a full half mile at WOT/Redline. Those gears have to be perfectly in sync, or else your talking MASSIVE destruction.

Yeah, we were cracking up about it last night. The absolute lowest boost we could get out of a 3.6, and still keep a 4" pulley, is like 12psi. The difference between the 3.6 and 2.8 is freaking huge.
So are these blowers geared more toward higher boost levels, than say a Magnuson? Are these boost levels more a result of efficiency and the twist and lobes on the rotors? The one 5.0 Mustang article stated in order for the TVS to make like 20 psi, it had to spin 18,000 RPMs, while the 2.8H had to only spin like 12,000 (if the numbers aren't exactly correct, I apologize - I think they're close though...), at least on that combination of pulleys and what not. If the rotors between the two were geared the same, are we looking at different results? Are my questions just irrelevent because it's my understanding rotor speed will effect pressure/temperatures, so is it best to run the lowest possible rotor speed to get the desired boost pressure so the heat generated by pressurizing the air will be as low as possible? Maybe this is the basis of a lot of my confusion/questions. It seems, to me, that the more total area the rotors have, the more air they can process/pressurize, and if you spin them less, the lower the IATs, the better for durability, power, and performance.

I guess I'm asking is what is it that makes twin screws superior, even to the new hybrid TVS rotors? Is it because of what I'm thinking above, or am I way off?
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Old 01-12-2010, 03:00 PM   #62
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Too bad this never became available for the G8's. I wonder if this kit could be made to work with some modifications.
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Old 01-12-2010, 03:22 PM   #63
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We've been working with Casey out here in Vegas. He has a G8. We designed the kit around his car, and are ready to install it, but he called us and told us he was robbed, and they stole a bunch of money from him. Being that he was letting us use his car, we had offered him a kit at a severly discounted rate, but he wants to do a 416 at the same time. So we are definately doing the kit, we are just waiting on casey to recoupe his losses from the robbery. If he can not do it some time this spring, then we'll locate another car, but he has been such a great guy, we would prefer to wait on him.

Yes, this kit shares alot of the same components. But there is still quite a bit of new parts that had to be made. We already had the kit on caseys car a while back, when we were designing it, we just need his car to finalize it. Problem is, is the G8's are so few and far between. I am praying that GM continues them in another lineup.
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Too bad this never became available for the G8's. I wonder if this kit could be made to work with some modifications.
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Old 01-12-2010, 03:28 PM   #64
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So did you say the main head of the blower is interchangable? Say someone gets a 2.8 and decides later on with a built motor they want a 3.6. Possible to use the same intake setup and just change the blower case w/ rotors etc?

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Old 01-12-2010, 04:09 PM   #65
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Well, first off, its way less complicated than one may think.

First off, no, the KB is not more ideal at high boost. Its just more ideal PERIOD. There are many factors that contribute to this, but ill point out a few. One of which is called "Adiabatic Efficiency". If you think back to colledge physics, try to remember "The Ideal Gas Law". Essentially, anytime you compress a fluid (air is a form of that) you generate heat. So adiabatic efficiency is the percentege of heat generated when the fluid is compressed. ie.. Even with 100% adiabatic efficiency, SOME heat will be generated.
But the greater the efficiency, the less heat generation; With less heat generation, there is a higher air density. The higher the density, the greater amount of O2. Boost, is NOT the most important, air density is. Point being, you want your supercharger to have the highest possible adiabatic efficiency. The lower it has, the more heat it generates per pound of boost.

Next, you need to factor in parasitic loss. This is the amount of horsepower it takes to drive the supercharger. This amount of power consumption is directly taken off of the net power. So even if 2 superchargers are making the exact same rwhp of 500rwhp, if 1 unit is consuming 25 more rwhp, then one car will make 475rwhp, and the other 500rwhp. This is why alot of times you see cars with the same boost, and the same overall build, but one is making more/less power.

The reason why the KB is able to make the same boost at a much much lower rpm, is due to the explanations above. Its a compilation of all of them. adiabatic efficiency, shear volume of air per rotation, and some parasitic loss.

Example. If I have one blower that is less efficient, the blower will generate much higher discharge temps. These temps have a direct effect on boost. Hot air is less dense. This means, I will have to spin the blower harder to make up for that loss. The next is volume of air. If we are able to produce 2.8L of air per revolution, and the other is only able to produce 2.3L of air, which blower is going to create the boost sooner? We all know that boost is just a measurement of restriction.

In the end, the slower you spin the blower, the LESS heat that is generated. This heat that is generated from the head unit has a direct negative effect on adiabatic efficiency. Why? Because as the head unit heats up, it aids in heating the charge air. The less heat, the higher net horsepower (not factoring parasitic loss). This is why when we compared the 2.8H to the 2.6, we were able to gain over 25hp simply due to the fact that we could slow the 2.8 down, and still make the same boost. We saw 30* cooler charge temps.

When I mentioned the "Gears" on the supercharger, that is not something that can be changed. The timing of the gears is critical, and the perfect balance between the male and female rotor has already been obtained. This allows KB to run between 4"-2.5" pulleys, and hit pretty much any boost level they need. By changing the gearing, it would negatively effect way to much. Its not an option.

I hope this info helps, as well as answers your question. If not, let me know.
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So are these blowers geared more toward higher boost levels, than say a Magnuson? Are these boost levels more a result of efficiency and the twist and lobes on the rotors? The one 5.0 Mustang article stated in order for the TVS to make like 20 psi, it had to spin 18,000 RPMs, while the 2.8H had to only spin like 12,000 (if the numbers aren't exactly correct, I apologize - I think they're close though...), at least on that combination of pulleys and what not. If the rotors between the two were geared the same, are we looking at different results? Are my questions just irrelevent because it's my understanding rotor speed will effect pressure/temperatures, so is it best to run the lowest possible rotor speed to get the desired boost pressure so the heat generated by pressurizing the air will be as low as possible? Maybe this is the basis of a lot of my confusion/questions. It seems, to me, that the more total area the rotors have, the more air they can process/pressurize, and if you spin them less, the lower the IATs, the better for durability, power, and performance.

I guess I'm asking is what is it that makes twin screws superior, even to the new hybrid TVS rotors? Is it because of what I'm thinking above, or am I way off?
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Old 01-12-2010, 04:10 PM   #66
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Yes, you can swap head units down the road. Its a direct bolt on swap.
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So did you say the main head of the blower is interchangable? Say someone gets a 2.8 and decides later on with a built motor they want a 3.6. Possible to use the same intake setup and just change the blower case w/ rotors etc?

Regards,
William
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Old 01-12-2010, 04:15 PM   #67
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HOLLY SCHNIKIES!!! I'm going to have to read that a couple times, but have the general understanding. Thanks, sincerely, for taking the time to put that together. That's been one of the best reads I've had, especially on this topic.
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Old 01-12-2010, 04:17 PM   #68
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I saw something that is an interesting read. Although it discusses an outdated Eaton M-90 roots blower, hopefully some of the physics will help understand.

Im not discussing the Eaton, or attempting to explain why some feel its inferior inferior, only posting the actual physics behind compressed air temps. Just disregard where it mentions the old eaton's, as we all know they have changed over to the TVS style.



The Eaton M-90 blower (supercharger) is a roots type positive displacement pump which traces its roots back to the 1800's with the Roots brothers. The supercharger is matched to the engine by its displacement and belt ratio; by pumping more air into the intake than the engine can use, air pressure and density are increased in the intake manifold, resulting in positive manifold pressure (boost). By stuffing more air (and of course, the right amount of fuel with this extra air) into the combustion chambers, more power is produced.
A normally aspirated (NA) (non-supercharged) engine's maximum manifold pressure will never exceed the outside ambient barometric pressure for the altitude. For example, at sea level this will be 100 Kpa (Kilopascals) or zero psi of "boost" at wide open throttle (WOT). Thus, if you drive a NA car at high altitude, you'll experience decreased performance since the air is thinner and less dense. This is reflected by your manifold absolute pressure (MAP), which will indicate less than 100 Kpa or "negative" boost (vacuum) at WOT. Additionally, if you drive below sea level in Death Valley for instance, you'll experience increased performance because of the denser air. Of course, that's if you don't detonate your engine to death from the intense dry heat, but that's another subject! You'll actually see the MAP read above 100 Kpa, and show some "boost" due to the increased air density - a natural "supercharging" effect.
Roots type pumps were actually not originally intended for use as air compressors (our understanding is they were designed, of all things, as blowers for ventilation!) so some of this increased manifold pressure is recycled back into the blower case, reducing efficiency and creating additional heat. Anytime a fluid is compressed (yes air is a fluid), heat is produced - this is a fundamental law of physics called the ideal gas law - so even at 100% adiabatic efficiency, some heat will be produced when air is compressed simply due to this law. However, we all know that there must be heat created in compressing this air due to friction, so this lowers the adiabatic efficiency. Roots type blowers are actually quite inefficient since they create a great deal of heat under boost. Adiabatic efficiencies of typical roots blowers are only around 50%, but fortunately for us, the Eaton unit is actually an improved roots design due to their twisted helix rotor. Each rotor is twisted 60 degrees to form this helix, improving efficiency and reducing pressure fluctuations.
A common misconception is that more boost is always better. This is true, but only to a certain extent, because superchargers operate most efficiently at a certain speed. To create more boost, blower speed must be increased, more heat is generated, and efficiency suffers. One must understand that high density is what's important, not necessarily high pressure (boost). Compressing air does increase both pressure and density, but the resulting heat generated simultaneously reduces density as well. To achieve optimum performance from a blower, we want to create the most pressure (boost) while adding the least amount of heat, thus achieving the highest air density possible in the intake manifold. As blower speed is increased, at some point the heat created decreases the air density to where addidtional boost is just offset by the increased heat, resulting in no density (and therefore power) gains; further increases in boost may actually even decrease power.

Ok, what exactly is the function of an intercooler?
The function of an intercooler is to remove heat from the inlet air charge. As explained above, removing heat increases the density (more molecules per unit area) of the inlet charge allowing more fuel to combust with the end result being increased HP. Another benefit is greater resistance to detonation.
Definition of terms
T1 = blower inlet temperature
T2 = blower outlet temperature
T3 = intercooler exit temp
T4 = intercooler coolant temp
P1 = absolute ambient pressure (approx. 14.7 psi)
P2 = absolute pressure at blower outlet (boost + P1)
° R = ° F + 460
According to the Ideal Gas Law (PV = nRT) anytime a gas is compressed, its temperature rises. In a perfect world, the temperature rise purely from compressing air (assuming 100% adiabatic efficiency, neglecting frictional heat) is given by:
Example: T1 = 85° , P1 = 14.7, P2 = 25.7

Unfortunately, because the Roots style blower is far from an ideal adiabatic compressor, it also adds heat to the charge.

Working through this equation with an efficiency of 60% (remember the Eaton twisted helix roots design is more efficient than conventional roots blowers at 50%), we get an actual T2 of ~241° F, and this is very close to what we've actually measured from our thermocoupled engineering development vehicle.
What does this mean in terms of power?
As stated above, the more dense the inlet air charge, the more fuel we can burn, therefore resulting in more power. The density ratio of the inlet air charge is an indicator of the power gain.

The density ratio in the above example works out to:

Therefore, the blower is helping us make 36% more power than a normally aspirated engine.
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Old 01-12-2010, 04:22 PM   #69
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HAHA, Im sure were gonna get a few engineers that will laugh at my explanation, but I tried to explain it in term I would personally understand. Which is about an 8th grade level.. So although it may not be technicaly written to the letter of what an engineer would say, hopefully it explains what I was trying to relay.
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HOLLY SCHNIKIES!!! I'm going to have to read that a couple times, but have the general understanding. Thanks, sincerely, for taking the time to put that together. That's been one of the best reads I've had, especially on this topic.
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Old 01-12-2010, 04:23 PM   #70
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You've spent so much time trying to show us, but couldn't you have spent a little more time translating this to stupid, like I am? j/k
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Old 01-12-2010, 04:25 PM   #71
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Originally Posted by Total_Perf_Eng View Post
HAHA, Im sure were gonna get a few engineers that will laugh at my explanation, but I tried to explain it in term I would personally understand. Which is about an 8th grade level.. So although it may not be technicaly written to the letter of what an engineer would say, hopefully it explains what I was trying to relay.
Yeah - I have to speak to engineers for my line of work and you can tell when they don't really want you to understand what they're saying. Your posts have been very helpful, and I'm gaining more appreciation for these twin screws I've heard so much about in the past
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Old 01-12-2010, 04:28 PM   #72
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You can only translate if you fully understand what it says..
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Originally Posted by radz282003 View Post
You've spent so much time trying to show us, but couldn't you have spent a little more time translating this to stupid, like I am? j/k
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Old 01-12-2010, 04:31 PM   #73
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It's not that engineers don't want you to understand, many times you just have to have an extensive background to understand the reasoning behind things. Thanks for the posts, as an engineer I actually appreciate the physics behind it
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Old 01-12-2010, 04:32 PM   #74
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Originally Posted by Total_Perf_Eng View Post
You can only translate if you fully understand what it says..
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Old 01-12-2010, 04:36 PM   #75
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It's not that engineers don't want you to understand, many times you just have to have an extensive background to understand the reasoning behind things. Thanks for the posts, as an engineer I actually appreciate the physics behind it
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