First off, I don't need aftermarket forced induction to be knowledgeable on the subject. I've done my research, talked to people experienced on the matter and while my Z still
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03-04-2012, 11:20 PM | #91 (permalink) |
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First off, I don't need aftermarket forced induction to be knowledgeable on the subject. I've done my research, talked to people experienced on the matter and while my Z still remains N/A (a good decision considering that F.I. options continue to grow i.e. GTM's twin supercharger ) I built a car running forced induction before. Driving one on the norm as opposed to not doesn't make one more knowledgeable than the other. With that said, members with the 7at have repeatedly stated they are hesitant or downright unwilling to achieve their full potential of power and torque because they have the 7AT. So, not only can you NOT hammer it in 5th gear and above, 5th gear being the "cruising" hear for the 7AT's but there is power out there that you can't confidently utilize.
Now you don't have to take my word for it so here is what GTM had to say, I saved you the work of having to do the search for yourself. GTM states: Generally, when an OEM designs a transmission, they have a specific torque capacity in mind and use this capacity to specify the number of clutch disks used in each clutch pack. The valve body is also programmed to operate these clutch packs in a specified manner. For example, when cruising in 5th gear on a 5 speed automatic, the transmission will only downshift to 4th gear when a certain amount of pedal pressure is applied for a certain amount of time. Because 5th gear is used mainly for cruising, there are less clutches in the clutch pack and therefore, the ultimate holding capacity is less than that of the lower gears that are used more for accelerating. In the case of a 7 speed automatic, both 6th and 7th use fewer clutch packs with 5th being a transition gear still using fewer clutches than 1st – 4th. When more power is added, more load is placed on these clutch packs. One way to prevent premature wear of the clutch packs is to modify the valve body to increase hydraulic pressure so that the transmission will downshift more readily. A modified valve body also shifts faster and slips the clutches less to achieve a firmer feeling when the transmission shifts. This keeps the transmission in lower gears when you are trying to accelerate the car with more torque. On the new 7 speed automatic, line pressure can be increased by reflashing the ECU. When going for serious power, however, increased line pressure simply isn’t enough. Even with a heavy duty transmission fluid cooler and valve body upgrade, more than doubling the factory rated horsepower requires more extensive work to keep the transmission working well. In this case, it is necessary to overhaul the transmission and replace the clutch packs, pistons that actuate the clutches and drums that hold the clutches with high performance versions. The drums must be enlarged to accommodate additional clutches and a more aggressive friction material must be selected for the clutches themselves. In addition, the piston diameters are increased to apply additional force to the clutch packs. While these modifications increase the holding capacity of the transmission, it is not indestructible as there is only so much room for additional clutch packs, larger drums and pistons. Ultimately, care must be used when driving a vehicle equipped with an automatic transmission and aftermarket forced induction. When accelerating in a high gear, damage can result with the additional torque. Therefore, it is vital that the driver is aware of the limitations of the transmission and downshift when they want to accelerate. High speed runs at full boost in high gears is inadvisable with an automatic transmission, modified or otherwise. Remember that the transmission was not designed for those operating parameters. This doesn’t mean that forced induction cannot be added to an automatic transmission equipped car,just that care and caution must be exercised in addition to supporting modifications appropriate to the power level achieved. I know the UpRev software can effect the shift points etc., that's why its the preferable tuning program and by all means hammer it in any gear you want. Thankfully guys like Sam will be there to assist you when you have failed to exercise "care and caution." All you have to do is bring the $$$.
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03-04-2012, 11:22 PM | #92 (permalink) |
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OP, I see you have the unorthodox pulleys. Do you think they added to your great #'s or do you feel that with the TT's they provide marginal gains at best?
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03-05-2012, 12:59 AM | #94 (permalink) |
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I think N/A the NST pulley kit nets about 10wph so I'm guessing he is getting a larger gain then this. That is a good question though, I wonder how much or approximately how much the kit is actually helping.
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03-05-2012, 04:39 AM | #95 (permalink) | |
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I asked a simple question that sparked a copy and paste wall post. You keep mentioning 5th gear and smashing the gas and not taking care and caution. My 3rd and 4th gear were fried due to lack of line pressure because the ecu was expecting a certain amount of torque but instead saw probably double it. With that said, I rolled the dice on ths transmission. Now I just bring the $$$. Just another day. However, The negligence on my tuner's end accelerated my transmission's failure. Torque management is a great feature. Oh and I never smashed the pedal in 5th or 6th. Sent from my SPH-D710 using Tapatalk |
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03-05-2012, 11:34 AM | #96 (permalink) |
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Unorthodox is a very very good mod with turbo and light flywheel and clutch. Turbos come on much earlier and while cruising the engine works wayyyyyyy less even at speeds of 80mph.
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03-05-2012, 12:01 PM | #97 (permalink) | |
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03-05-2012, 12:32 PM | #99 (permalink) |
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Working on it, then anticipating long hours at the office. I lucked out, in a horrible market for legal jobs I have a pretty good one. Once all the formalities are sorted out and I get the Mrs. a nice "I did it" gift, I can start saving for forced induction.
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03-05-2012, 12:33 PM | #100 (permalink) | |
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Second, underdrive pulleys usually underdrive by <= 10%, which means at best you are saving 10% of what the accessory parasitic loss is, which is small compared to the total output of the engine while cruising. I'm not saying that you can't make more power from pulleys (warnings from reputable tuners notwithstanding), but they are certainly going to be very nominal overall.
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03-05-2012, 02:22 PM | #101 (permalink) | |
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03-05-2012, 04:32 PM | #102 (permalink) |
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Have a 7 speed and before my part out i took it to a runway event and took it to 140+ kept it smashed on 5th gear. Car runs fine and I took about 6-7 runs a few back to back.
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03-05-2012, 06:41 PM | #104 (permalink) | |
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What you are saying is different and misleading. Certainly if you can accelerate through the RPM band (under load) faster, you will be able to spool your turbos faster as measured from some point in time because the car is more powerful and able to get to that RPM point faster. However, you will not be able to spool the turbos any faster with reference to your RPMs because the pulleys do not affect exhaust flow in any way at all. Using our example above, you would still hit X psi at 4000 RPMs with or without the pulleys, however, it may take you 1/2 second less to hit 4000 RPMs because of the increase in power. Turbos run off of exhaust flow, plain and simple, and anyone who thinks a pulley is going to make their turbo spool faster is kidding themselves.
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03-05-2012, 07:24 PM | #105 (permalink) | |
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I stand corrected! With those mods the time between hitting the throttle and your car start to go a hell of a lot faster will be less. Will that help you sleep tonite? lolololol. In other words the turbos if they spool at 2000 rpms will still spool at 2000 rpms but 2000 rpms but you will get from 0 to 2000 rpms much faster with those mods. Thanks einstein^ |
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