Shelby Posted February 11, 2009 Report Share Posted February 11, 2009 if you place a restriction on the turbine hot side out let you just stop'd the turbo from working it will not push air , Link to comment Share on other sites More sharing options...
Maxzillian Posted February 11, 2009 Report Share Posted February 11, 2009 It has to be turbine inlet pressure. That much back pressure for the turbine outlet is almost unthinkable. Now, a 1:1 ratio or less is very rare, but it's not impossible. Granted, for most applications you'll never want a ratio that low. The spool up would be horrible for anything driven on the street. Link to comment Share on other sites More sharing options...
Shelby Posted February 12, 2009 Report Share Posted February 12, 2009 what would be a pratical set up to test exh manifold back pressure , i have done after turbine system back pressure testing and let me tell you fire travels a long way up the test tube even a small one , i end 'd up with 12 ft 3/16th copper tubeing coil'd up to make room for it and 8 ft of 3/16th vacum hose to a 5" sensitive pressure gauge in side the car so i could see it under full boost conditions i doubt the same set up would work for befor turbo testing Link to comment Share on other sites More sharing options...
ernielist Posted February 13, 2009 Report Share Posted February 13, 2009 I <3 data. Can't thank you enough for going to the trouble. I want to take your numbers and try to figure out what gains I could potentially make from an intercooler only change. I still use a modified stock intercooler with 2.25in pipes welded to the end tanks in place of the stock 1 7/8ths pipes. Yes the holes were enlarged to 2.25. I've been hoping for someone to collect data on the stocker to help me decide whether to spring for a quality intercooler or try one of the ebay cheapies. Any thoughts? Been reading this thread and the info is great, but hos about this argument for air-to-air vs air-to-water? There is an overwhelming quantity of ambient air available to cool an air-to-air core relative to the charge air thru the inside of the intercooler (The iced down water intercooler is the only exception to this argument.). At just 60 mph, with a 300 bhp engine at full tilt, the ambient air available to cool the intercooler is about ten times the amount of charge air needed to make the 300 hp. Whereas the water intercooler largely stores the heat in the water until off throttle allows a reverse exchange. Some heat is expelled from a front water cooler, but the temperature difference between the water and ambient air is not large enough to drive out much heat. Another way to view the situation is that ultimately the heat removed from the air charge must go into the atmosphere regardless of whether it's from an air intercooler or a water based intercooler. The problem with the water intercooler is that the heat has more barriers to cross to reach the atmosphere than the air intercooler. Like it or not, each barrier represents a resistance to the transfer of heat. The net result; more barriers, less heat transfer Link to comment Share on other sites More sharing options...
scott87star Posted February 13, 2009 Author Report Share Posted February 13, 2009 what would be a pratical set up to test exh manifold back pressure , As long as you dead end the tube into the pressure gauge you don't get dramatic heat transfer, only heat transmitted via that being attached to a hot object instead of heat transmitted by flowing hot gas. My setup has about 24 inches of 1/8" OD tubing between the bulkhead fitting on the exhaust manifold and the pressure gauge and there is very little noticeable heat at the gauge/tube junction even after boosting. I can touch it with my hand. There is an overwhelming quantity of ambient air available to cool an air-to-air core relative to the charge air thru the inside of the intercooler (The iced down water intercooler is the only exception to this argument.). At just 60 mph, with a 300 bhp engine at full tilt, the ambient air available to cool the intercooler is about ten times the amount of charge air needed to make the 300 hp. Whereas the water intercooler largely stores the heat in the water until off throttle allows a reverse exchange. Some heat is expelled from a front water cooler, but the temperature difference between the water and ambient air is not large enough to drive out much heat. Another way to view the situation is that ultimately the heat removed from the air charge must go into the atmosphere regardless of whether it's from an air intercooler or a water based intercooler. The problem with the water intercooler is that the heat has more barriers to cross to reach the atmosphere than the air intercooler. Like it or not, each barrier represents a resistance to the transfer of heat. The net result; more barriers, less heat transfer It's all in what you want to achieve, you are absolutely correct in your argument but you have to balance that thermal efficiency advantage against a larger pressure drop, more complicated "big tube" plumbing and absolute area to mount the heat exchanger. The starquest has plenty of area for the air to air heat exchanger but running the bigger diameter tubes to and from the heat exchanger tends to push things like the battery out of the engine compartment. Air to water units have really low pressure drop, like 0.1 psi compared to the 2+ that I measured, and are very compact. I haven't decided yet but right now I'm leaning toward an air-water unit for my upgrade. Scott Link to comment Share on other sites More sharing options...
ernielist Posted February 13, 2009 Report Share Posted February 13, 2009 (edited) As long as you dead end the tube into the pressure gauge you don't get dramatic heat transfer, only heat transmitted via that being attached to a hot object instead of heat transmitted by flowing hot gas. My setup has about 24 inches of 1/8" OD tubing between the bulkhead fitting on the exhaust manifold and the pressure gauge and there is very little noticeable heat at the gauge/tube junction even after boosting. I can touch it with my hand. It's all in what you want to achieve, you are absolutely correct in your argument but you have to balance that thermal efficiency advantage against a larger pressure drop, more complicated "big tube" plumbing and absolute area to mount the heat exchanger. The starquest has plenty of area for the air to air heat exchanger but running the bigger diameter tubes to and from the heat exchanger tends to push things like the battery out of the engine compartment. Air to water units have really low pressure drop, like 0.1 psi compared to the 2+ that I measured, and are very compact. I haven't decided yet but right now I'm leaning toward an air-water unit for my upgrade. Scott In relation to the mods we would mostly be doing to our cars however very seldom. While the loss through the intercooler is proportional to the flow (CFM) squared, unlikely the change will be of a magnitude that requires a bigger intercooler. If dramatic changes in flow are created, say 50%, then the flow loss would increase by 1.5 squared, or 2.25, and that would prove excessive thus strongly suggesting a larger intercooler. You seem to know more about this so please correct this if its wrong? Edited February 13, 2009 by ernielist Link to comment Share on other sites More sharing options...
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