Gen 3 Roe Blower ready by VOI 10
- Thread starter black mamba1
- Start date
GTS Bruce
Enthusiast
Forget about it. Jm heads and cam with a DC tune and forget about it. Adding all the x-tra weight to the nose is ok for drag racers but a handling penalty on road courses and the street where you go around corners and use the brakes. GTS Bruce
chimazo
Enthusiast
Billy Glidden and some others may debate you on that
Good call, Tony. I should have prefaced it with, "of those that run blowers..."
Steve 00RT/10
Enthusiast
Ron,
I certainly won't argue automotive powertrain dogma with you, but I can always use a little schooling.
You can break your car loose at 60-65 MPH in 3rd.which is roughly 3100 rpm with 18" tires & around 2900 with 19" tires. Looking at a recent log, my car is boosting around 4.5 pounds at 3K rpm. You are roughly at the same boost level as me at that RPM...maybe a little less. I can't break the tires (PS2s) loose at that speed unless it's a little damp or a slippery road.
Are you not exerting similar forces -- maybe more -- on your engine? Also, I'm told that the stock Viper valve train (GEN I,II) is not well suited to continued high rpms -- where Paxtons thrive. I rarely shift over 5300 RPM, thereby decreasing valve train fatigue.
As I have the lowly 5 pound pulley, many more miles than most, and all other components stock -- are you saying that I am the exception? I kind of doubt that. I have never heard of a 5 pound Roe failure. The very few failed units I've read about are all higher pully applications, typically with only one card, and timing removed to eke out a very minor amount of HP.
Pushing the envelope so to speak, or not having a good grasp of the limitations of the system for detonation in temperature variation (I am now tuned with one card for 30F-100F -- works slick)
I have nothing against centrifugal blowers. I just happen to think that for 99% of all street Viper use, the twin screw approach provides more SOTP bang for the buck. In reality, how often does one get over 100 MPH on the street. Quick blasts up to that speed and quickly back down to legal probably accounts for most Viper miles. In that arena, I don't think the 100 extra HP you have is as much a factor. As for track use, 3 times to Gingerman has shown no heat soak whatsoever -- at least based on straightaway speeds. My last trip around this year, with Sue in the car, had me a little higher than earlier in the day in some places. (4th gear only)
A few years down the road when we hit 150K miles on this set up we can compare notes again. I'm guessing your car will never see that kind of mileage
Steve
I certainly won't argue automotive powertrain dogma with you, but I can always use a little schooling.
You can break your car loose at 60-65 MPH in 3rd.which is roughly 3100 rpm with 18" tires & around 2900 with 19" tires. Looking at a recent log, my car is boosting around 4.5 pounds at 3K rpm. You are roughly at the same boost level as me at that RPM...maybe a little less. I can't break the tires (PS2s) loose at that speed unless it's a little damp or a slippery road.
Are you not exerting similar forces -- maybe more -- on your engine? Also, I'm told that the stock Viper valve train (GEN I,II) is not well suited to continued high rpms -- where Paxtons thrive. I rarely shift over 5300 RPM, thereby decreasing valve train fatigue.
As I have the lowly 5 pound pulley, many more miles than most, and all other components stock -- are you saying that I am the exception? I kind of doubt that. I have never heard of a 5 pound Roe failure. The very few failed units I've read about are all higher pully applications, typically with only one card, and timing removed to eke out a very minor amount of HP.
Pushing the envelope so to speak, or not having a good grasp of the limitations of the system for detonation in temperature variation (I am now tuned with one card for 30F-100F -- works slick)
I have nothing against centrifugal blowers. I just happen to think that for 99% of all street Viper use, the twin screw approach provides more SOTP bang for the buck. In reality, how often does one get over 100 MPH on the street. Quick blasts up to that speed and quickly back down to legal probably accounts for most Viper miles. In that arena, I don't think the 100 extra HP you have is as much a factor. As for track use, 3 times to Gingerman has shown no heat soak whatsoever -- at least based on straightaway speeds. My last trip around this year, with Sue in the car, had me a little higher than earlier in the day in some places. (4th gear only)
A few years down the road when we hit 150K miles on this set up we can compare notes again. I'm guessing your car will never see that kind of mileage
Steve
i think the roe is great when at that level steve is at. they seem to be PERFECT there. anything more im not sure of.....
steve do you run W/M on that one ?
and god bless ya, with that many miles on it, GOOD FOR YOU !
steve do you run W/M on that one ?
and god bless ya, with that many miles on it, GOOD FOR YOU !
Nine Ball
Enthusiast
I have a Paxton on my '06 (675 rwhp) and I'd rather have a roots style blower or a screwcharger. I've owned several of both, and prefer the throttle response and low/mid range full boost that a roots/screw provides.
Anyone complaining about having too much power or torque at low RPM just needs to learn how to drive. That is what your throttle pedal is for! Honestly, I find my Paxton pretty boring until 4th gear on the highway. I rarely get the opportunity to wind it out like that. Sometimes I like being able to roast the tires from a 50 mph roll, and the Paxton won't do that.
My twin-turbo '06 GTO makes 100 rwhp less than my Viper and it is WAY more fun to drive. I had a roots blower on my previous C6 and it was also more fun to drive than the Viper. I like the Viper better, but not the way the power comes on with a centrifugal blower. It takes too long and needs too much RPM. I won't buy another centrifugal blower again, I'd rather have a stroker engine instead.
Anyone complaining about having too much power or torque at low RPM just needs to learn how to drive. That is what your throttle pedal is for! Honestly, I find my Paxton pretty boring until 4th gear on the highway. I rarely get the opportunity to wind it out like that. Sometimes I like being able to roast the tires from a 50 mph roll, and the Paxton won't do that.
My twin-turbo '06 GTO makes 100 rwhp less than my Viper and it is WAY more fun to drive. I had a roots blower on my previous C6 and it was also more fun to drive than the Viper. I like the Viper better, but not the way the power comes on with a centrifugal blower. It takes too long and needs too much RPM. I won't buy another centrifugal blower again, I'd rather have a stroker engine instead.
Steve, I was more speaking of those that increase the Roe performance level up to abouut the same as the Paxton for overall performance. I believe that would be an 8 psi version on a Gen II. Your peak torque is not much different than mine (approx 600 lb-ft), but based on the technology comes on sooner and acts more like a larger displacement engine. That is effectively what positive displacement superchargers do. Becasue the efficiency is fairly constant tuning should indeed be more straight forward than with nonlinear devices such as the centrifugal supercharger. Some of that tuning potential is thrown away with the Roe based on the location of the inlet temperature sensor. As the engine controller does not know the actual inlet temperature. Given that it is not intercooled the ratio of actual inlet temperature versus airbox temperature is fairly predictable. If you know the boost, supercharger efficiency and the initial inlet temperature you can reasonably calculate the supercharger outlet temperature. Throw on a intercooler and that predictability goes out the window. Conversely, the Paxton uses a post intercooler temperature sensor. The boost may not be predictable but engine control is straight forward as air flow calculations using inlet pressure and temperature (both down stream of the intercooler) follow the normal logic of speed density control, which the Viper is from 1992 through 2006.
As to the additional fatigue provided by the superchargers increased torque, yes it is indeed lessened by the limitation in tire slip while in lower gears slip occurs. But all slip is not equal. If you cause dramiatic slip (i.e. quick, not so much the final slip speed) the torque translates to driveline acceleration. So if all you do is "just" slip the tires the tires act as a torque fuse. But if you accelerate them rapidly the entire driveline sees a higher torque than the tires themselves can absorb. Once you are in higher gears the full torque is applied to all components upstream of the engaged transmission gears. So WOT forays in higher gears do indeed stress the engine, clutch and forward transmission elements. Components downstream of the transmission torque multiplication also see proportionally higher torque, though lower than that seen in higher numerical gear (i.e 1st) . But since fatigue life is a composite of all load cycles, an increase at any point degrades the longevity. There is no question that any method of increasing engine performance will deteriorate component life as a result.
What the ultimate life of the components depends on so many factors it is not predictable. But lessened life is absolute. Your driving style has much to do with it. And since much of your mileage has been long distance I would bet your WOT time is way less than the average on a per mile driven basis. Unless of course you drive at top speed
We should learn from what we have observed. That is at every significant increase in engine torque the Viper has upgraded the driveline elements as they needed it. And a Gen III Paxton produces a peak torque fairly close to the 2008. You do the math.
As to the additional fatigue provided by the superchargers increased torque, yes it is indeed lessened by the limitation in tire slip while in lower gears slip occurs. But all slip is not equal. If you cause dramiatic slip (i.e. quick, not so much the final slip speed) the torque translates to driveline acceleration. So if all you do is "just" slip the tires the tires act as a torque fuse. But if you accelerate them rapidly the entire driveline sees a higher torque than the tires themselves can absorb. Once you are in higher gears the full torque is applied to all components upstream of the engaged transmission gears. So WOT forays in higher gears do indeed stress the engine, clutch and forward transmission elements. Components downstream of the transmission torque multiplication also see proportionally higher torque, though lower than that seen in higher numerical gear (i.e 1st) . But since fatigue life is a composite of all load cycles, an increase at any point degrades the longevity. There is no question that any method of increasing engine performance will deteriorate component life as a result.
What the ultimate life of the components depends on so many factors it is not predictable. But lessened life is absolute. Your driving style has much to do with it. And since much of your mileage has been long distance I would bet your WOT time is way less than the average on a per mile driven basis. Unless of course you drive at top speed
We should learn from what we have observed. That is at every significant increase in engine torque the Viper has upgraded the driveline elements as they needed it. And a Gen III Paxton produces a peak torque fairly close to the 2008. You do the math.
Joseph Dell
Enthusiast
The best part about the ROE Gen3 is that it gives Gen3 folks CHOICES!!! The paxton set-up for the Gen3 is a stellar set-up right out of the box. But I expect the same thing out of the ROE set-up! So this just means that those who like the ROE can now use it. It isn't a better-or-worse discussion. In fact, we don't even have regular viper races or a viper racing league where we could even begin to test and compare the two! But for those who want it, there is now a choice B.
Can't wait to see some of these on the road!!!
JD
Can't wait to see some of these on the road!!!
JD
Steve 00RT/10
Enthusiast
Thanks. We bought it to drive. No doubt about that. No W/M. (either car) I wanted to keep it as simple as possible. Plus, I can't afford to give up the trunk room. Over the last 8 years of creative Viper packing for as long as 2 weeks, ....shows that cavity holding a lot of 'stuff'
Steve, I was more speaking of those that increase the Roe performance level up to abouut the same as the Paxton for overall performance. I believe that would be an 8 psi version on a Gen II. Your peak torque is not much different than mine (approx 600 lb-ft), but based on the technology comes on sooner and acts more like a larger displacement engine. That is effectively what positive displacement superchargers do. Becasue the efficiency is fairly constant tuning should indeed be more straight forward than with nonlinear devices such as the centrifugal supercharger. Some of that tuning potential is thrown away with the Roe based on the location of the inlet temperature sensor. As the engine controller does not know the actual inlet temperature. Given that it is not intercooled the ratio of actual inlet temperature versus airbox temperature is fairly predictable. If you know the boost, supercharger efficiency and the initial inlet temperature you can reasonably calculate the supercharger outlet temperature. Throw on a intercooler and that predictability goes out the window. Conversely, the Paxton uses a post intercooler temperature sensor. The boost may not be predictable but engine control is straight forward as air flow calculations using inlet pressure and temperature (both down stream of the intercooler) follow the normal logic of speed density control, which the Viper is from 1992 through 2006.
I agree about the limitations of the IAT sensor on the Roe. As you state without W/M shooting into the intake tubes, It becomes easier to equate. I think it becomes a relative thing if basing tuning on the WB AFR result. The VEC 3 IAT addition, while not perfect, works quite well for me. But along those same lines, wouldn't it also be a relative relationship with the W/M and IAT function? In other words, can't the resultant AFR be used to add or subtract fuel?
As to the additional fatigue provided by the superchargers increased torque, yes it is indeed lessened by the limitation in tire slip while in lower gears slip occurs. But all slip is not equal. If you cause dramiatic slip (i.e. quick, not so much the final slip speed) the torque translates to driveline acceleration. So if all you do is "just" slip the tires the tires act as a torque fuse. But if you accelerate them rapidly the entire driveline sees a higher torque than the tires themselves can absorb. Once you are in higher gears the full torque is applied to all components upstream of the engaged transmission gears. So WOT forays in higher gears do indeed stress the engine, clutch and forward transmission elements. Components downstream of the transmission torque multiplication also see proportionally higher torque, though lower than that seen in higher numerical gear (i.e 1st) . But since fatigue life is a composite of all load cycles, an increase at any point degrades the longevity. There is no question that any method of increasing engine performance will deteriorate component life as a result.
What the ultimate life of the components depends on so many factors it is not predictable. But lessened life is absolute. Your driving style has much to do with it. And since much of your mileage has been long distance I would bet your WOT time is way less than the average on a per mile driven basis. Unless of course you drive at top speed
Yeah but....Let's say a stock Viper can go at 200,000 miles without issue -- and a induced motor goes 50,000 less ( these being completely arbitrary numbers ).........isn't it a moot argument? At 80,000, I already have more miles than most reading here will ever experience...with no problems to date (knock on wood). In other words, lessened life may be absolute, but that amount of miles will likely never be seen by 99% of all Vipers. BTW. This last 1100 mile trip to G-Man (100 track miles) saw me use less than 1/4 qt of oil (some through the intake) over the entire trip. Not bad for almost 80K on the clock and oil changes, with analysis, every 6-10K miles.
You are correct about many of our miles being long distance. I would guess about 50-60%. That being said, I probably drive around here daily no different than the majority of Vipers. A bread and milk run will routinely see my foot mashed to the floor. In that respect, my WOT miles are the same, and more (about 4,500 non road trip miles per season), than most. Next, throw in probably 3 dozen xcrosses and 6 or 7 all day track events, and we've evened the playing field some. I do agree that my set up at 5 pounds is the easiest to tune and the least ******* the entire drive train. But then, that's my whole point in throwing this into this thread. Keep it simple and you should be able to drive your Roe car w/o issue for as long as you choose to.
Didn't you tell me recently that you had some noise coming from the Paxton area now? And also that you do notice some heat soak at G-man? I have a lot more miles on my Roe than you have on your Paxton.
We should learn from what we have observed. That is at every significant increase in engine torque the Viper has upgraded the driveline elements as they needed it. And a Gen III Paxton produces a peak torque fairly close to the 2008. You do the math.
I'll leave the math for the engineers.
Steve
Noise is from the Paxton bearing itself. Something I noticed over time that bearing noise has increased. Lubrication has been verified and could just be a normal aging effect. I have nearly 25,000 miles on my Paxton and I would expect that mine, with many less highway miles, has a higher ratio of WOT activity. I also rarely drive without investigating the performance envelope.
Heat soak is a physical characteristic and does not indicate anything with respect to durability (though it does impact thermal loading of the exhaust valve and exaust system). It means decreasing performance as the inlet temperatures build. That can be caused by a variety of factors. In this case it is because the Paxton intercooler system cannot keep up with the heat addition under continuous or near continuous high rpm conditions (note this is rpm and not WOT related). Becasue the Paxton has a post intercooler temperature sensor the ECU measures the inlet temperature and "protects" the motor by retarding spark and adding additonal fuel. Those factors plus the reduced volumetric efficiency related to the temperature itself is the cause for heat soaked power loss. These are part of the base engine calibration.
One thing is clear here. You speak of how easy it is to calibrate the Roe. But the fact that you have needed to do that and spend many hours doing so under a variety of conditions belies the fact that it is not easy and must be done so uniquely for every vehicle and driving location. If you moved to the mountains you would be redoing it completely. With the Paxton, and any well sorted system, you would just drive it. I have not adjusted or calibrated anything beyond the 6000 - 6200 rpm fuel map points, and those were done over 4 years ago. Not one second in calibration since. And those points were for my own satisfaction. I would expect the majority of Paxton owners install and drive.
As to the 200,000 mile durability and 50,000 mile reduction estimate I will send you a typical s-n curve for steel (s-n curves relates stress and cycles for fatigue analysis). That way you can see how a stress change of 50-70% can impact the fatigue limit. remember in all supersharged engines the actual applied force on the piston (IMEP) is higher than on a naturally aspirated motor of the same output. Simply because the piston energy must also drive the supercharger, which may be in the 50-100 hp range. So a stock engine with 450 lb-ft increased to 600 lb ft (33% increase) may actually have a IMEP increase of 50%. A 50% increase in stress will reduce the fatigue life by a substatial margin. Your "hope" is that all of the power delivery components have been well overdesigned. That is aligned with my hope, but hope is all it is. If the hope is not realised it will be $$$ in place of hope.
Heat soak is a physical characteristic and does not indicate anything with respect to durability (though it does impact thermal loading of the exhaust valve and exaust system). It means decreasing performance as the inlet temperatures build. That can be caused by a variety of factors. In this case it is because the Paxton intercooler system cannot keep up with the heat addition under continuous or near continuous high rpm conditions (note this is rpm and not WOT related). Becasue the Paxton has a post intercooler temperature sensor the ECU measures the inlet temperature and "protects" the motor by retarding spark and adding additonal fuel. Those factors plus the reduced volumetric efficiency related to the temperature itself is the cause for heat soaked power loss. These are part of the base engine calibration.
One thing is clear here. You speak of how easy it is to calibrate the Roe. But the fact that you have needed to do that and spend many hours doing so under a variety of conditions belies the fact that it is not easy and must be done so uniquely for every vehicle and driving location. If you moved to the mountains you would be redoing it completely. With the Paxton, and any well sorted system, you would just drive it. I have not adjusted or calibrated anything beyond the 6000 - 6200 rpm fuel map points, and those were done over 4 years ago. Not one second in calibration since. And those points were for my own satisfaction. I would expect the majority of Paxton owners install and drive.
As to the 200,000 mile durability and 50,000 mile reduction estimate I will send you a typical s-n curve for steel (s-n curves relates stress and cycles for fatigue analysis). That way you can see how a stress change of 50-70% can impact the fatigue limit. remember in all supersharged engines the actual applied force on the piston (IMEP) is higher than on a naturally aspirated motor of the same output. Simply because the piston energy must also drive the supercharger, which may be in the 50-100 hp range. So a stock engine with 450 lb-ft increased to 600 lb ft (33% increase) may actually have a IMEP increase of 50%. A 50% increase in stress will reduce the fatigue life by a substatial margin. Your "hope" is that all of the power delivery components have been well overdesigned. That is aligned with my hope, but hope is all it is. If the hope is not realised it will be $$$ in place of hope.
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OP
OP
black mamba1
Enthusiast
Excellent point! You are very logical, sure you arent a Vulcan?
OP
OP
black mamba1
Enthusiast
Ken, you are not only a very good Viper tech, you are an awesome driver to get those times!
OP
OP
black mamba1
Enthusiast
Steve, I was more speaking of those that increase the Roe performance level up to abouut the same as the Paxton for overall performance. I believe that would be an 8 psi version on a Gen II. Your peak torque is not much different than mine (approx 600 lb-ft), but based on the technology comes on sooner and acts more like a larger displacement engine. That is effectively what positive displacement superchargers do. Becasue the efficiency is fairly constant tuning should indeed be more straight forward than with nonlinear devices such as the centrifugal supercharger. Some of that tuning potential is thrown away with the Roe based on the location of the inlet temperature sensor. As the engine controller does not know the actual inlet temperature. Given that it is not intercooled the ratio of actual inlet temperature versus airbox temperature is fairly predictable. If you know the boost, supercharger efficiency and the initial inlet temperature you can reasonably calculate the supercharger outlet temperature. Throw on a intercooler and that predictability goes out the window. Conversely, the Paxton uses a post intercooler temperature sensor. The boost may not be predictable but engine control is straight forward as air flow calculations using inlet pressure and temperature (both down stream of the intercooler) follow the normal logic of speed density control, which the Viper is from 1992 through 2006.
As to the additional fatigue provided by the superchargers increased torque, yes it is indeed lessened by the limitation in tire slip while in lower gears slip occurs. But all slip is not equal. If you cause dramiatic slip (i.e. quick, not so much the final slip speed) the torque translates to driveline acceleration. So if all you do is "just" slip the tires the tires act as a torque fuse. But if you accelerate them rapidly the entire driveline sees a higher torque than the tires themselves can absorb. Once you are in higher gears the full torque is applied to all components upstream of the engaged transmission gears. So WOT forays in higher gears do indeed stress the engine, clutch and forward transmission elements. Components downstream of the transmission torque multiplication also see proportionally higher torque, though lower than that seen in higher numerical gear (i.e 1st) . But since fatigue life is a composite of all load cycles, an increase at any point degrades the longevity. There is no question that any method of increasing engine performance will deteriorate component life as a result.
What the ultimate life of the components depends on so many factors it is not predictable. But lessened life is absolute. Your driving style has much to do with it. And since much of your mileage has been long distance I would bet your WOT time is way less than the average on a per mile driven basis. Unless of course you drive at top speed
We should learn from what we have observed. That is at every significant increase in engine torque the Viper has upgraded the driveline elements as they needed it. And a Gen III Paxton produces a peak torque fairly close to the 2008. You do the math.
Excellent post Gr8! Feels like I am back in Mechanical Systems in my M.E. class! Good stuff.
Steve 00RT/10
Enthusiast
Got the graph. Thanks. A little above my pay grade, but I will noodle a little more on it. I didn't think the Roe required that kind of HP to drive it?
I'd like to think the engine was designed well enough to last at least 200K miles. Time will tell. We are way ahead of most on the Viper pleasure curve and all is well. I've seen 1989 SHOs with 450,000 miles (7K tach -- engine never apart) doing road track stuff in 100 degree heat and never miss a beat. I'd like to think Dodge made as good a product as that Yamaha engine.
BTW......Jim C has a rear intercooler. You might want to touch base with him.
Steve
Steve,
I installed the Paxton starting in November of the first year I had it. Something like 3-4k when installed. Supercharger friction horsepower is related to airflow and pressure rise. Efficiency comes into play but not that much different when comparing the peak drive power points. Efficiency graphs of various types of superchargers are available. No doubt the twin screw is good. The centrifugal is not that much lower. Where it fails in comparison is the lineararity in producing flow (which translates to boost).
To my knowledge no gasoline engine for a production car is designed to live a minimum of 200k miles. Especially in the conditions you state (road racing in 100 F ). That type of expectation, especially for a high performance application is not reasonable. Unless of course you want a car engine like a diesel truck.
This whole topic is about Gen III supercharging. The Gen II Paxton is not as well sorted as you know. As such the Gen II choice you made was the best choice. And no one knows how well sorted the Gen III Roe will be. What we do know is that it requires a new hood. I have not heard if it is intercooled and how its control system is architected beyond Sean stating that it would not use a VEC
I talked with Dave (Jim C's mechanic) about his setup. That was part of got me thinking about doing that. More fluid volume and a place for airflow that does not adversely impact engine cooling.
I installed the Paxton starting in November of the first year I had it. Something like 3-4k when installed. Supercharger friction horsepower is related to airflow and pressure rise. Efficiency comes into play but not that much different when comparing the peak drive power points. Efficiency graphs of various types of superchargers are available. No doubt the twin screw is good. The centrifugal is not that much lower. Where it fails in comparison is the lineararity in producing flow (which translates to boost).
To my knowledge no gasoline engine for a production car is designed to live a minimum of 200k miles. Especially in the conditions you state (road racing in 100 F ). That type of expectation, especially for a high performance application is not reasonable. Unless of course you want a car engine like a diesel truck.
This whole topic is about Gen III supercharging. The Gen II Paxton is not as well sorted as you know. As such the Gen II choice you made was the best choice. And no one knows how well sorted the Gen III Roe will be. What we do know is that it requires a new hood. I have not heard if it is intercooled and how its control system is architected beyond Sean stating that it would not use a VEC
I talked with Dave (Jim C's mechanic) about his setup. That was part of got me thinking about doing that. More fluid volume and a place for airflow that does not adversely impact engine cooling.
Wow! Lots of detail here now. From my "living with these systems" point of view, I still stand by my comments with the Whipple/Roe/Saleen/Lyscolm set-up. For me it hsa proven the best.
In the end, I would rather screw than blow, but that is just me.
In the end, I would rather screw than blow, but that is just me.
OP
OP
black mamba1
Enthusiast
Hilarious!
OP
OP
black mamba1
Enthusiast
The thing is, 650 rwhp on a Roe is equal to like 750 rwhp on a Paxton.
From what I have seen and heard from Sean is there will be two intake versions, one that can be used to fit the kit under a stock 03-06 hood and another that will only fit under an 08. The only issue is the lower profile intake will come at an additional cost of 1200-1700 which is the cost of a new 08 hood painted.
I think that technically its: "be screwed or be blown". Want to change your mind?
99 R/T 10
Enthusiast
Hi Everyone,
I wasn't on the board this weekend, so I just read through this.
I'll take some time to respond tonight with some more details about the differences in the kits.
Meanwhile, for the engineering types, here's the graph I work off of showing power draw, efficiency, discharge temperature, etc, for the Autorotor twin screw. This is running 1.6 bar (8.8 psi) boost.
Regards,
Sean
I wasn't on the board this weekend, so I just read through this.
I'll take some time to respond tonight with some more details about the differences in the kits.
Meanwhile, for the engineering types, here's the graph I work off of showing power draw, efficiency, discharge temperature, etc, for the Autorotor twin screw. This is running 1.6 bar (8.8 psi) boost.
You must be registered for see images
Regards,
Sean
Thanks Sean. Overall efficiency looks lower than I would have expected. I expected more like 75% - 80% peak adiabatic efficiency. A peak power draw of a little over 60 hp seems reasonable for the pressure and flow.
Are you planning for an intercooler or just protect for the 80+C temp rise? If intercooled are you planning on relocating the temp sensor to the discharge side?
With a mass flow of 34 kg/min at a maximum I am not seeing the capacity to achieve the 0.6 bar test condition. The 8.3L engine should be fairly close to 14-15 kg/min at 3000 rpm (mid speed point on the graph). The output at that speed shows only about 17 kg/min, which would provide about a 0.13-.21 bar or 2-3 psi boost. Am I missing something? Maybe you are overdriving it such that at engine red-line the supercharger shaft speed is more than the maximum on the graph. If so the delta T at the peak speed would start to become problematic one would think.
Are you planning for an intercooler or just protect for the 80+C temp rise? If intercooled are you planning on relocating the temp sensor to the discharge side?
With a mass flow of 34 kg/min at a maximum I am not seeing the capacity to achieve the 0.6 bar test condition. The 8.3L engine should be fairly close to 14-15 kg/min at 3000 rpm (mid speed point on the graph). The output at that speed shows only about 17 kg/min, which would provide about a 0.13-.21 bar or 2-3 psi boost. Am I missing something? Maybe you are overdriving it such that at engine red-line the supercharger shaft speed is more than the maximum on the graph. If so the delta T at the peak speed would start to become problematic one would think.
Interesting. Bottom line: Less efficient supercharger than you believe is reasonably possible and it is producing less boost than projected. Correct?
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