Air Intake tubes?
01-03-2005, 03:53 PM
#61
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Pappy,
Did you notice what typically happens to water temp when you were doing your hood down tests, stationary ?
The mapping of injector pulse versus water temp may be a factor in this. i.e. the signal from temp sensor 2 to the ECU.
Did you notice what typically happens to water temp when you were doing your hood down tests, stationary ?
The mapping of injector pulse versus water temp may be a factor in this. i.e. the signal from temp sensor 2 to the ECU.
01-03-2005, 04:03 PM
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John,
Do you want real temps or what the gauge read at idle? At idle the gauge read 5/8 or two needles below the 2/3 mark on a US 89 S4. The thermostat is 75C. I can go back and obtain actual water temp if that would help (top of the radiator). The fans were cycling during all tests.
Do you want real temps or what the gauge read at idle? At idle the gauge read 5/8 or two needles below the 2/3 mark on a US 89 S4. The thermostat is 75C. I can go back and obtain actual water temp if that would help (top of the radiator). The fans were cycling during all tests.
01-03-2005, 04:13 PM
#63
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Well, what I was after is the change of water temp at temp sensor 2 (or just the change of resistance) during your typical "red light stop" period.
I have of course observed an increase of water temp when car is at a standstill in hot weather, but haven't checked the temp rise versus time.
I have of course observed an increase of water temp when car is at a standstill in hot weather, but haven't checked the temp rise versus time.
01-03-2005, 04:14 PM
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Um,
If all one cares about is to get off the line faster, then one can change the gearing for torque multiplication, and pick up a bit of extra power from the gearing. This will give all the launch to 60mph one will need.. Now, granted the looks part of the equation or the "bling" will have extra value if cool looking parts are under the hood.
While understanding many of these parameters, I would have to agree with MK... I can see the point Pappy et. al. is trying to make, and I'm a fan of John Speake's work. However, while all this dropping of the intake temp is admirable, the amount (mass) of air we are talking about is not significant in a NA car..
If you really want to do something about intake charge without gearing reduction etc. then, build a Supercharger with a very large intercooler, or possible a sub-cooling system. A perfect example would be the Ford system that uses the AC to subcool the IC fluid for short bursts of 30 seconds. You would pick up the most gain this way. The combination of air MASS and FUEL combines to make power in an engine.
When the temp sensor tells the LH to lean the mixture, it is because the DENSITY RATIO, NOT MASS of the air is less by the algorithm calculations in the LH program. The amount of air MASS say in 1 Kg of air is constant irrespective of temperature. (Heat a Kg of air, and weigh it, you will see.)
Intercoolers and the like affect DENSITY RATIO, not MASS.. In addition, air being one of the poorest insulators cannot transfer that much heat from the parts to the intake airflow given the volume of airflow. The heat is mostly coming from the intake ambient temp, and not the intake tubes.... In which case, if you really want to do something about this, as I mentioned earlier, develop a subcooling system to reduce the ambient temp...
A cheap solution may be to use a Cryo (CO2) sprayer to spray the intake plenum so it "freezes"... A much more complicated solution would of course be a supercharger system with a chiller for the stoplight Grand Prix... Now, my $.02 on stoplight stuff is to just get a Dragster, after all they are designed for that.. A 928 was not..... (designed to be a stoplight GP contender). This 0-60 bit is overrated, and a hype by magazines and companies in the USA to sell more stuff that is irrelevant to the average car nut. With proper gearing on many of the "average or regular" cars, many of the production car stoplight kings would be left out in the cold.
The WOT MK spoke of is where it's at guys.... Everyone should experience this feeling in their 928 or any other car for that matter.... Shucks, take a trip to Germany, rent a decent car, and go for it... You don't even have to drive on the Nurburgring, just find an Autobahn with an unrestricted section, and punch the pedal and hold it there for a while...... 60mph will feel extremely slow once you get to 150+ and stay there for several miles...
Either way, congrats on your experimentation, and the data you privide... Pappy, you have my sympathy for being stuck in LA and not getting to use your 928 as it was intended. Maybe you should move up here to the central coast. 60 is slow on the freeway, you would get to go at least 80. In addition, we have average temps in the 70's all year round, and Laguna Seca is very interesting to carry out some of those experiments you like to do...
Cheers,
If all one cares about is to get off the line faster, then one can change the gearing for torque multiplication, and pick up a bit of extra power from the gearing. This will give all the launch to 60mph one will need.. Now, granted the looks part of the equation or the "bling" will have extra value if cool looking parts are under the hood.
While understanding many of these parameters, I would have to agree with MK... I can see the point Pappy et. al. is trying to make, and I'm a fan of John Speake's work. However, while all this dropping of the intake temp is admirable, the amount (mass) of air we are talking about is not significant in a NA car..
If you really want to do something about intake charge without gearing reduction etc. then, build a Supercharger with a very large intercooler, or possible a sub-cooling system. A perfect example would be the Ford system that uses the AC to subcool the IC fluid for short bursts of 30 seconds. You would pick up the most gain this way. The combination of air MASS and FUEL combines to make power in an engine.
When the temp sensor tells the LH to lean the mixture, it is because the DENSITY RATIO, NOT MASS of the air is less by the algorithm calculations in the LH program. The amount of air MASS say in 1 Kg of air is constant irrespective of temperature. (Heat a Kg of air, and weigh it, you will see.)
Intercoolers and the like affect DENSITY RATIO, not MASS.. In addition, air being one of the poorest insulators cannot transfer that much heat from the parts to the intake airflow given the volume of airflow. The heat is mostly coming from the intake ambient temp, and not the intake tubes.... In which case, if you really want to do something about this, as I mentioned earlier, develop a subcooling system to reduce the ambient temp...
A cheap solution may be to use a Cryo (CO2) sprayer to spray the intake plenum so it "freezes"... A much more complicated solution would of course be a supercharger system with a chiller for the stoplight Grand Prix... Now, my $.02 on stoplight stuff is to just get a Dragster, after all they are designed for that.. A 928 was not..... (designed to be a stoplight GP contender). This 0-60 bit is overrated, and a hype by magazines and companies in the USA to sell more stuff that is irrelevant to the average car nut. With proper gearing on many of the "average or regular" cars, many of the production car stoplight kings would be left out in the cold.
The WOT MK spoke of is where it's at guys.... Everyone should experience this feeling in their 928 or any other car for that matter.... Shucks, take a trip to Germany, rent a decent car, and go for it... You don't even have to drive on the Nurburgring, just find an Autobahn with an unrestricted section, and punch the pedal and hold it there for a while...... 60mph will feel extremely slow once you get to 150+ and stay there for several miles...
Either way, congrats on your experimentation, and the data you privide... Pappy, you have my sympathy for being stuck in LA and not getting to use your 928 as it was intended. Maybe you should move up here to the central coast. 60 is slow on the freeway, you would get to go at least 80. In addition, we have average temps in the 70's all year round, and Laguna Seca is very interesting to carry out some of those experiments you like to do...
Cheers,
01-03-2005, 04:21 PM
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Originally Posted by pappy92651
John,
Do you want real temps or what the gauge read at idle? At idle the gauge read 5/8 or two needles below the 2/3 mark on a US 89 S4. The thermostat is 75C. I can go back and obtain actual water temp if that would help (top of the radiator). The fans were cycling during all tests.
Do you want real temps or what the gauge read at idle? At idle the gauge read 5/8 or two needles below the 2/3 mark on a US 89 S4. The thermostat is 75C. I can go back and obtain actual water temp if that would help (top of the radiator). The fans were cycling during all tests.
FYI, there is a great little spot on top of the water crossover manifold that you can tap for an autometer water temp gauge. It sits right next to the stock temp sensor. Might be a good thing for you to add as well?
I did it when i had mine all apart during the SC install. Its nice knowing EXCATLY what the water temp is and also what temp corresponds to which "white line" on the stock gauge, as that has always been a grey area.
Example: : mine runs at a needle above the white line"..."below"..."2/3rds " ..."14/32nds
" bottom of the red warning"....etc etc. With the autometer there is no "grey area" your displaying an numeric value.
01-03-2005, 04:37 PM
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Originally Posted by John Speake
Well, what I was after is the change of water temp at temp sensor 2 (or just the change of resistance) during your typical "red light stop" period.
I have of course observed an increase of water temp when car is at a standstill in hot weather, but haven't checked the temp rise versus time.
I have of course observed an increase of water temp when car is at a standstill in hot weather, but haven't checked the temp rise versus time.
I will run the experiment again once the roads dry out. At the moment it would probably take 1/2 hour to get the car up to temp. Unusual weather for us. This is on my to do list.
01-03-2005, 04:42 PM
#67
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I dont usually race from idle oneward, usually, we rev the engines up for a seocond or so and then launch. this would clear ALL hot air from the tubes and you would be left what i have described, a slow heat transfer from the associated intake components. i have no mods done to the car except the headers, exhaust and intake air box vents with brake duct tubes (and the air box is sealed with cauking as well) "launching like a rabbit" , this means more hp, agreed, and we have not seen any of this on the dyno with a hot intake or cold intake. keep in mind, even if you could reduce the temps (actual intake charge) by 20f degrees, is only about 3hp!!! you CANNOT feel this!!
Now your testing me with a question about intercoolers? You may know this, but the idea of a intercooler is all about heat transfer. with air moving through vains (think radiator for cooling water) but much larger, but longer, the air moves through a air radiator to lower the temps. it has a much longer resident time as the molecules release their heat into the aluminum fin'ed box to release into the atomosphere. the main reason to use this is not for NA engines, but for turbocharged engines where the delta T is Tremendous. turbos/superchargers compress air, for which heat is generated (PV/NRT)
some of the turbos get air up to 300 degrees F. it takes an intercooler to bring temps with ambient flow through it, to down to 200 or even 150 degrees. This is not only a way to gain hp , but a way to keep from detonation. (dual gain) the more you reduce temps, the greater the hp will be. but we are talking 100 to 200 degree temp drops. on a NA car, the 1psi drop across a common intercooler will negate ANY gains of temp reduction. this is why intercoolers are not used on NA cars!!! cold air intakes are used, but our cars are already being fed by cold air to begin with. NOT to belabor the point again, but the resident time the air takes at WOT or even 4000rpm is not long enough to heat the air much after the tubes and intake plenum volume has been cleared ( 1/10 of a second)
any gains of "cooler" air off the line, is preceived and will not even show up at the dyno. if it does, its in the 2-3hp range, and this is insignificant.
If you want to have the effects of ram air at 200mph (ie approx .7psi gain) standing still, you should seriously consider the eRAM. it removes the restriction of stock air boxes and gains .5 psi on top of that for a 1psi net gain in pressure. its an axial flow device that can move 1000cfm at 26,000rpm through a 3.5" opening. (and belt out 3.5lbs of static thrust) the gains of this would far exceed anything you could produce in trying to cool the air with insulation tubes, vents , etc.
check out www.electricsupercharger.com
Mk
Now your testing me with a question about intercoolers? You may know this, but the idea of a intercooler is all about heat transfer. with air moving through vains (think radiator for cooling water) but much larger, but longer, the air moves through a air radiator to lower the temps. it has a much longer resident time as the molecules release their heat into the aluminum fin'ed box to release into the atomosphere. the main reason to use this is not for NA engines, but for turbocharged engines where the delta T is Tremendous. turbos/superchargers compress air, for which heat is generated (PV/NRT)
some of the turbos get air up to 300 degrees F. it takes an intercooler to bring temps with ambient flow through it, to down to 200 or even 150 degrees. This is not only a way to gain hp , but a way to keep from detonation. (dual gain) the more you reduce temps, the greater the hp will be. but we are talking 100 to 200 degree temp drops. on a NA car, the 1psi drop across a common intercooler will negate ANY gains of temp reduction. this is why intercoolers are not used on NA cars!!! cold air intakes are used, but our cars are already being fed by cold air to begin with. NOT to belabor the point again, but the resident time the air takes at WOT or even 4000rpm is not long enough to heat the air much after the tubes and intake plenum volume has been cleared ( 1/10 of a second)
any gains of "cooler" air off the line, is preceived and will not even show up at the dyno. if it does, its in the 2-3hp range, and this is insignificant.
If you want to have the effects of ram air at 200mph (ie approx .7psi gain) standing still, you should seriously consider the eRAM. it removes the restriction of stock air boxes and gains .5 psi on top of that for a 1psi net gain in pressure. its an axial flow device that can move 1000cfm at 26,000rpm through a 3.5" opening. (and belt out 3.5lbs of static thrust) the gains of this would far exceed anything you could produce in trying to cool the air with insulation tubes, vents , etc.
check out www.electricsupercharger.com
Mk
Originally Posted by pappy92651
Mark,
This is what I'm talking about. If your particular 928 does not drop power off idle when the intake is hot then you have modified something to compensate for it. If you remove the hood or bring cold air to the intake tubes the car launches like a rabbit. All stock S4 / GTS models behave the same. The computer is leaning the mixture because sensors are telling it to. With a very lean mixture at launch power is reduced and the engine is likely to ping causing the computer to retard timing.
Cooler intake charges do increase HP. It does show up during dyno testing.
Home work: What is an intercooler used for?
Tony,
You have experienced the same thing. This is true of every S4 that I have driven. They lack power from a standing start until they cool off.
This is what I'm talking about. If your particular 928 does not drop power off idle when the intake is hot then you have modified something to compensate for it. If you remove the hood or bring cold air to the intake tubes the car launches like a rabbit. All stock S4 / GTS models behave the same. The computer is leaning the mixture because sensors are telling it to. With a very lean mixture at launch power is reduced and the engine is likely to ping causing the computer to retard timing.
Cooler intake charges do increase HP. It does show up during dyno testing.
Home work: What is an intercooler used for?
Tony,
You have experienced the same thing. This is true of every S4 that I have driven. They lack power from a standing start until they cool off.
01-03-2005, 04:44 PM
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Originally Posted by Tony
FYI, there is a great little spot on top of the water crossover manifold that you can tap for an autometer water temp gauge. It sits right next to the stock temp sensor. Might be a good thing for you to add as well?
I did it when i had mine all apart during the SC install. Its nice knowing EXCATLY what the water temp is and also what temp corresponds to which "white line" on the stock gauge, as that has always been a grey area.
Example: : mine runs at a needle above the white line"..."below"..."2/3rds " ..."14/32nds " bottom of the red warning"....etc etc.
With the autometer there is no "grey area" your displaying an numeric value.
I did it when i had mine all apart during the SC install. Its nice knowing EXCATLY what the water temp is and also what temp corresponds to which "white line" on the stock gauge, as that has always been a grey area.
Example: : mine runs at a needle above the white line"..."below"..."2/3rds " ..."14/32nds
" bottom of the red warning"....etc etc. With the autometer there is no "grey area" your displaying an numeric value.
I will have the opportunity to do this on the new motor. Good idea.
01-03-2005, 04:52 PM
#69
Rennlist Member
Yes, your right. However, density ratio and mass flow is the same.
when the pressure drops, the relative volume used by an engine stays the same, but at a lower pressure, right? this means mass flow is reduced.
our engines will always draw 500cfm at 6000rpm . the question is what the density of that 500cfm is. when you heat the air, the molecules are further apart so less can fit in a set space or volume or volume flow.
the heat transfer is greatest coming right from the blistering hot heads, attached to the metal intakes!!! now, you could make the entire intake out of carbon fiber, but then the heat has to be dissapated by the water now. (more load on the cooling system. Point in case, i dont think mark anderson has noticed a bit of extra heat in his engine. He is burning 65 more hp, (close to 50,000watts) AND he has removed the metal intake with carbon fiber. (so any heat of the prior intake is now going somewhere, right???? So, the discussion is in concept interesting, but meaningless in our quest for more hp (even a little!)
you want to add cold air, try NOS (see NOS threads on the list!)
vent the air box and be done with it!!!
by the way, the first stage of the venting of my air box is on the 928trackcars web page www.928trackcars.com/kibort
I later added one more vent. (these vents are spare inlets from the 928 over the radiator put in) So basically, i doubled the inlet area of the air box, with half of them pointed at the base of the windshield.
MK
when the pressure drops, the relative volume used by an engine stays the same, but at a lower pressure, right? this means mass flow is reduced.
our engines will always draw 500cfm at 6000rpm . the question is what the density of that 500cfm is. when you heat the air, the molecules are further apart so less can fit in a set space or volume or volume flow.
the heat transfer is greatest coming right from the blistering hot heads, attached to the metal intakes!!! now, you could make the entire intake out of carbon fiber, but then the heat has to be dissapated by the water now. (more load on the cooling system. Point in case, i dont think mark anderson has noticed a bit of extra heat in his engine. He is burning 65 more hp, (close to 50,000watts) AND he has removed the metal intake with carbon fiber. (so any heat of the prior intake is now going somewhere, right???? So, the discussion is in concept interesting, but meaningless in our quest for more hp (even a little!)
you want to add cold air, try NOS (see NOS threads on the list!)
vent the air box and be done with it!!!
by the way, the first stage of the venting of my air box is on the 928trackcars web page www.928trackcars.com/kibort
I later added one more vent. (these vents are spare inlets from the 928 over the radiator put in) So basically, i doubled the inlet area of the air box, with half of them pointed at the base of the windshield.
MK
Originally Posted by blau928
Um,
While understanding many of these parameters, I would have to agree with MK... I can see the point Pappy et. al. is trying to make, and I'm a fan of John Speake's work. However, while all this dropping of the intake temp is admirable, the amount (mass) of air we are talking about is not significant in a NA car..
When the temp sensor tells the LH to lean the mixture, it is because the DENSITY RATIO, NOT MASS of the air is less by the algorithm calculations in the LH program. The amount of air MASS say in 1 Kg of air is constant irrespective of temperature. (Heat a Kg of air, and weigh it, you will see.)
Intercoolers and the like affect DENSITY RATIO, not MASS.. In addition, air being one of the poorest insulators cannot transfer that much heat from the parts to the intake airflow given the volume of airflow. The heat is mostly coming from the intake ambient temp, and not the intake tubes.... In which case, if you really want to do something about this, as I mentioned earlier, develop a subcooling system to reduce the ambient temp...
A cheap solution may be to use a Cryo (CO2) sprayer to spray the intake plenum so it "freezes"... .
The WOT MK spoke of is where it's at guys.... Everyone should experience this feeling in their 928 or any other car for that matter.... Shucks, take a trip to Germany, rent a decent car, and go for it... You don't even have to drive on the Nurburgring, just find an Autobahn with an unrestricted section, and punch the pedal and hold it there for a while...... 60mph will feel extremely slow once you get to 150+ and stay there for several miles...
Either way, congrats on your experimentation, and the<a to carry out some of those experiments you like to do...
Cheers,
While understanding many of these parameters, I would have to agree with MK... I can see the point Pappy et. al. is trying to make, and I'm a fan of John Speake's work. However, while all this dropping of the intake temp is admirable, the amount (mass) of air we are talking about is not significant in a NA car..
When the temp sensor tells the LH to lean the mixture, it is because the DENSITY RATIO, NOT MASS of the air is less by the algorithm calculations in the LH program. The amount of air MASS say in 1 Kg of air is constant irrespective of temperature. (Heat a Kg of air, and weigh it, you will see.)
Intercoolers and the like affect DENSITY RATIO, not MASS.. In addition, air being one of the poorest insulators cannot transfer that much heat from the parts to the intake airflow given the volume of airflow. The heat is mostly coming from the intake ambient temp, and not the intake tubes.... In which case, if you really want to do something about this, as I mentioned earlier, develop a subcooling system to reduce the ambient temp...
A cheap solution may be to use a Cryo (CO2) sprayer to spray the intake plenum so it "freezes"... .
The WOT MK spoke of is where it's at guys.... Everyone should experience this feeling in their 928 or any other car for that matter.... Shucks, take a trip to Germany, rent a decent car, and go for it... You don't even have to drive on the Nurburgring, just find an Autobahn with an unrestricted section, and punch the pedal and hold it there for a while...... 60mph will feel extremely slow once you get to 150+ and stay there for several miles...
Either way, congrats on your experimentation, and the<a to carry out some of those experiments you like to do...
Cheers,
01-03-2005, 04:59 PM
#70
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Pappy, have you measured the surface temperature, at idle or after driving around, of any components associated with air flow intake? MAF, Throttle body, air box, intake tubes, plenum, the engine itself?...... Awhile back, I was messing around with my MAF after some in-town driving and it was so hot I couldn't touch it. That was AFTER air was passing through it.
If I was driving down the highway for 100 miles, it may have been cooler, along with the rest of the inline components...including the engine. But, the discussion is centered around in-town stop and go driving isn't it?
It would be interesting to know if there is a difference in intake air temperature just from insulating the top of the radiator (no other venting) so that the hot air created by engine heat wouldn't get sucked into the intake as easily.
It would also be interesting the know the overall difference in the engine temperature itself when running and/or idling with the hood scoop infront of the intake inlet and without ((does the hood scoop allow enough outside air into the intake tubes to actually lower the temp of the engine itself?)). If cooler air is constantly flowing through the intake, especially when idling, then the engine should constantly remain a little cooler; therefore, it should respond like it was a little cooler. Our cars are obviously sensitive to hot and cold air, so quick and easy access to outside air and the benefits it holds is plain common sense. The faster and more efficiently you can run cooler air through the 500 pound furnace under the hood, the better the potential for faster throttle response and more power at the wheels.
If I was driving down the highway for 100 miles, it may have been cooler, along with the rest of the inline components...including the engine. But, the discussion is centered around in-town stop and go driving isn't it?
It would be interesting to know if there is a difference in intake air temperature just from insulating the top of the radiator (no other venting) so that the hot air created by engine heat wouldn't get sucked into the intake as easily.
It would also be interesting the know the overall difference in the engine temperature itself when running and/or idling with the hood scoop infront of the intake inlet and without ((does the hood scoop allow enough outside air into the intake tubes to actually lower the temp of the engine itself?)). If cooler air is constantly flowing through the intake, especially when idling, then the engine should constantly remain a little cooler; therefore, it should respond like it was a little cooler. Our cars are obviously sensitive to hot and cold air, so quick and easy access to outside air and the benefits it holds is plain common sense. The faster and more efficiently you can run cooler air through the 500 pound furnace under the hood, the better the potential for faster throttle response and more power at the wheels.
01-03-2005, 05:02 PM
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Originally Posted by blau928
Um,
If all one cares about is to get off the line faster, then one can change the gearing for torque multiplication, and pick up a bit of extra power from the gearing. This will give all the launch to 60mph one will need.. Now, granted the looks part of the equation or the "bling" will have extra value if cool looking parts are under the hood.
While understanding many of these parameters, I would have to agree with MK... I can see the point Pappy et. al. is trying to make, and I'm a fan of John Speake's work. However, while all this dropping of the intake temp is admirable, the amount (mass) of air we are talking about is not significant in a NA car..
If you really want to do something about intake charge without gearing reduction etc. then, build a Supercharger with a very large intercooler, or possible a sub-cooling system. A perfect example would be the Ford system that uses the AC to subcool the IC fluid for short bursts of 30 seconds. You would pick up the most gain this way. The combination of air MASS and FUEL combines to make power in an engine.
When the temp sensor tells the LH to lean the mixture, it is because the DENSITY RATIO, NOT MASS of the air is less by the algorithm calculations in the LH program. The amount of air MASS say in 1 Kg of air is constant irrespective of temperature. (Heat a Kg of air, and weigh it, you will see.)
Intercoolers and the like affect DENSITY RATIO, not MASS.. In addition, air being one of the poorest insulators cannot transfer that much heat from the parts to the intake airflow given the volume of airflow. The heat is mostly coming from the intake ambient temp, and not the intake tubes.... In which case, if you really want to do something about this, as I mentioned earlier, develop a subcooling system to reduce the ambient temp...
A cheap solution may be to use a Cryo (CO2) sprayer to spray the intake plenum so it "freezes"... A much more complicated solution would of course be a supercharger system with a chiller for the stoplight Grand Prix... Now, my $.02 on stoplight stuff is to just get a Dragster, after all they are designed for that.. A 928 was not..... (designed to be a stoplight GP contender). This 0-60 bit is overrated, and a hype by magazines and companies in the USA to sell more stuff that is irrelevant to the average car nut. With proper gearing on many of the "average or regular" cars, many of the production car stoplight kings would be left out in the cold.
The WOT MK spoke of is where it's at guys.... Everyone should experience this feeling in their 928 or any other car for that matter.... Shucks, take a trip to Germany, rent a decent car, and go for it... You don't even have to drive on the Nurburgring, just find an Autobahn with an unrestricted section, and punch the pedal and hold it there for a while...... 60mph will feel extremely slow once you get to 150+ and stay there for several miles...
Either way, congrats on your experimentation, and the data you privide... Pappy, you have my sympathy for being stuck in LA and not getting to use your 928 as it was intended. Maybe you should move up here to the central coast. 60 is slow on the freeway, you would get to go at least 80. In addition, we have average temps in the 70's all year round, and Laguna Seca is very interesting to carry out some of those experiments you like to do...
Cheers,
If all one cares about is to get off the line faster, then one can change the gearing for torque multiplication, and pick up a bit of extra power from the gearing. This will give all the launch to 60mph one will need.. Now, granted the looks part of the equation or the "bling" will have extra value if cool looking parts are under the hood.
While understanding many of these parameters, I would have to agree with MK... I can see the point Pappy et. al. is trying to make, and I'm a fan of John Speake's work. However, while all this dropping of the intake temp is admirable, the amount (mass) of air we are talking about is not significant in a NA car..
If you really want to do something about intake charge without gearing reduction etc. then, build a Supercharger with a very large intercooler, or possible a sub-cooling system. A perfect example would be the Ford system that uses the AC to subcool the IC fluid for short bursts of 30 seconds. You would pick up the most gain this way. The combination of air MASS and FUEL combines to make power in an engine.
When the temp sensor tells the LH to lean the mixture, it is because the DENSITY RATIO, NOT MASS of the air is less by the algorithm calculations in the LH program. The amount of air MASS say in 1 Kg of air is constant irrespective of temperature. (Heat a Kg of air, and weigh it, you will see.)
Intercoolers and the like affect DENSITY RATIO, not MASS.. In addition, air being one of the poorest insulators cannot transfer that much heat from the parts to the intake airflow given the volume of airflow. The heat is mostly coming from the intake ambient temp, and not the intake tubes.... In which case, if you really want to do something about this, as I mentioned earlier, develop a subcooling system to reduce the ambient temp...
A cheap solution may be to use a Cryo (CO2) sprayer to spray the intake plenum so it "freezes"... A much more complicated solution would of course be a supercharger system with a chiller for the stoplight Grand Prix... Now, my $.02 on stoplight stuff is to just get a Dragster, after all they are designed for that.. A 928 was not..... (designed to be a stoplight GP contender). This 0-60 bit is overrated, and a hype by magazines and companies in the USA to sell more stuff that is irrelevant to the average car nut. With proper gearing on many of the "average or regular" cars, many of the production car stoplight kings would be left out in the cold.
The WOT MK spoke of is where it's at guys.... Everyone should experience this feeling in their 928 or any other car for that matter.... Shucks, take a trip to Germany, rent a decent car, and go for it... You don't even have to drive on the Nurburgring, just find an Autobahn with an unrestricted section, and punch the pedal and hold it there for a while...... 60mph will feel extremely slow once you get to 150+ and stay there for several miles...
Either way, congrats on your experimentation, and the data you privide... Pappy, you have my sympathy for being stuck in LA and not getting to use your 928 as it was intended. Maybe you should move up here to the central coast. 60 is slow on the freeway, you would get to go at least 80. In addition, we have average temps in the 70's all year round, and Laguna Seca is very interesting to carry out some of those experiments you like to do...
Cheers,
Richard,
Thank you for all of the ideas. I have been down the road on a few of these concepts already. 2400 RPM stall converter. The car used to do 0 to 60 in 4.6s. With the 285/30-18s it's up to 4.8s. Less wheel spin and slightly larger rolling diameter (24.6" Vs 24.9"). I think thats what also grenaded my planetary gears, too much traction / rwhp. All of this will change once the stroker goes in. I will be wanting more contact and a lower stall speed.
Back to the other issues. Yes, other cars are better suited to be dragsters. I do love WOT throttle runs. Perhaps I should move back to the CC (Cayucos). Very little traffic. Mark Kibort has some good points. Getting more air to the engine will have the greatest overall effect. The 0 to 60 phenomenon is simply a reality of local demographics. I'm trying to get everything sorted out before the big motor goes in, intake, exhaust, computer. It will never be finished and thats OK. It is amazing how much power these cars can handle in a controlled manner.
The exchange of ideas is important for those of us who want performance.
01-03-2005, 05:05 PM
#72
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So anyway, to answer the original question....
I replaced the tubes on both the 82 and 93 with stain/ heat resistant 3" flexable rubber venting hose. I got 6 foot lengths for each and cut to size. Cost per car was about $7.00. The ones on the 82 have been on for about a year now and they look as good as the ones I just put on the 93. They fit perfect, look perfect and though I have never dyno'd them, they work as well (if not better than) as the originals. Sucking sounds?...might be able to hear if the exhaust weren't so loud
Here are pics of both...
I replaced the tubes on both the 82 and 93 with stain/ heat resistant 3" flexable rubber venting hose. I got 6 foot lengths for each and cut to size. Cost per car was about $7.00. The ones on the 82 have been on for about a year now and they look as good as the ones I just put on the 93. They fit perfect, look perfect and though I have never dyno'd them, they work as well (if not better than) as the originals. Sucking sounds?...might be able to hear if the exhaust weren't so loud
Here are pics of both...
01-03-2005, 05:17 PM
#73
Nordschleife Master
Mark (and all)
Couple of things:
I measured 5hp _more_ with tubes than the open filter. That is, even with any drop, the heat difference (lower) provided 5hp more. How else to explain it?
5 cubic feet of air is a rectangle 5 feet by 1 foot by 1 foot. (not 5x5x5)
Lemme see...
Lower temps good. Higher temps bad. Free-flowing good. Restriction bad.
One thing to remember is that the intake system is restricted at several places. The tube diameter, even at the venturi, easily provides enough flow for the throttle and valves. Easy calculations to make. Looks like Porsche did.
As for improving power, seems like Pappy (et al?) are onto something. Get a cooler charge into the cylinder. Now is it cost effective and reliable?
Couple of things:
I measured 5hp _more_ with tubes than the open filter. That is, even with any drop, the heat difference (lower) provided 5hp more. How else to explain it?
5 cubic feet of air is a rectangle 5 feet by 1 foot by 1 foot. (not 5x5x5)
Lemme see...
Lower temps good. Higher temps bad. Free-flowing good. Restriction bad.
One thing to remember is that the intake system is restricted at several places. The tube diameter, even at the venturi, easily provides enough flow for the throttle and valves. Easy calculations to make. Looks like Porsche did.
As for improving power, seems like Pappy (et al?) are onto something. Get a cooler charge into the cylinder. Now is it cost effective and reliable?
01-03-2005, 05:38 PM
#74
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Hi Pappy,
I understand your issues, as I have 295/30-18 in back, and am in process of replacing my trans.. I had 285-30-18 until they wore out.. Looking to fit 305 or 335 without flaring much, as on MK's car they are quite nice under there.. When I am finished with the Compressor System, we will have similar issues, and I wil be replacing my planetaries with AMG units like yours. Still researching the intermediate shaft properties, and will also install an LSD. A gear splitter may be an interesting thing to consider as well...... I heard of one already done on a 928, but the person who did it is not too forthcoming about details etc. on the R'List.....
I don't know about you, but I have been in some very high HP 928's (over 500+ RWHP) on street and on track, and they are amazingly comfortable when prepared properly...
Too bad you had to leave Cayucos to go to LA.. I get down to SLO, Paso, and surrounding areas pretty often.... Almost bought some land in Edna Valley a couple years back..... Still love Carmel Valley though...
Keep us posted on your findings in the long quest for improvement...
MK,
We're on the same page....
I don't think anyone has calculated the density ratio on the 928 board to see what the air mass flow rate is under a multitude of conditions.. In any event, I think if the off idle, or launch is an issue, then just bolt on a blower, and call it a day... easiest bang for the $, unless you get mad scientist disease like some of us who just have to design and build our own systems...
Cheers,
I understand your issues, as I have 295/30-18 in back, and am in process of replacing my trans.. I had 285-30-18 until they wore out.. Looking to fit 305 or 335 without flaring much, as on MK's car they are quite nice under there.. When I am finished with the Compressor System, we will have similar issues, and I wil be replacing my planetaries with AMG units like yours. Still researching the intermediate shaft properties, and will also install an LSD. A gear splitter may be an interesting thing to consider as well...... I heard of one already done on a 928, but the person who did it is not too forthcoming about details etc. on the R'List.....
I don't know about you, but I have been in some very high HP 928's (over 500+ RWHP) on street and on track, and they are amazingly comfortable when prepared properly...
Too bad you had to leave Cayucos to go to LA.. I get down to SLO, Paso, and surrounding areas pretty often.... Almost bought some land in Edna Valley a couple years back..... Still love Carmel Valley though...
Keep us posted on your findings in the long quest for improvement...
MK,
We're on the same page....
I don't think anyone has calculated the density ratio on the 928 board to see what the air mass flow rate is under a multitude of conditions.. In any event, I think if the off idle, or launch is an issue, then just bolt on a blower, and call it a day... easiest bang for the $, unless you get mad scientist disease like some of us who just have to design and build our own systems...
Cheers,
01-03-2005, 05:46 PM
#75
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GlenL,
I'm sorry, I missed/can't remember which car you tested on.
Could it be a calibration issue that caused the drop with the tubes removed? IE. too much, or too turbulent airflow for the air meter for the fuel injection system tested?
Did you get a mixture graph too?
(BTW, I'm not questioning your data, just curious.
)
I'm sorry, I missed/can't remember which car you tested on.
Could it be a calibration issue that caused the drop with the tubes removed? IE. too much, or too turbulent airflow for the air meter for the fuel injection system tested?
Did you get a mixture graph too?
(BTW, I'm not questioning your data, just curious.
)