UR Crank with the Supercharger
#1
Suzuka Master
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UR Crank with the Supercharger
I have been asked about running the UR crank pulley with the SC kit and finally decided to run the numbers. This is just for the UR under drive crank pulley which is smaller than the stock crank pulley.
When the UR crank pulley is used with the SC kit, the blower would be turned only slightly faster than the engine even with the HBP. So you would only be making about 1.6 PSI boost. This would give up about 30 - 35 WHP at this low of boost; or the majority of the gain the SC provides.
Here are the numbers for the Accessory Belt (in millimeters):
Stock Crank / Alternator Side
175 / 67 = 2.612 Ratio
UR Crank / Alternator Side
141 / 67 = 2.104 Ratio
Here are the numbers for the SC Belt:
Base Pulley / SC Pulley
76 / 100 = 0.76 Ratio
HBP / SC Pulley
83 / 100 = 0.83 Ratio
To determine the final ratio, multiply the two values. For example with the standard SC kit:
2.612 * 0.76 = 1.985
In this case the blower is turning 1.985 times faster than the engine. This can be directly correlated to boost since it is a positive displacement blower.
For another example, using the HBP and the stock crank:
2.612 * 0.83 = 2.168
Using the UR crank pulley and the HBP gives the following ratio:
2.104 * 0.83 = 1.746
Obviously slower than even the base SC pulley with the stock crank. Here is how you use these ratios to determine boost. Since it is a 62ci blower it moves that amount every revolution. But since this is a four stroke engine, a cylinder only ingests every other revolution, we have to take half of our displacement. Half of our 3.2L in cubic inches is about 97.5ci.
To calculate the theoretical boost you use the following formula:
62 * Ratio / 97.5 * 14.7 - 14.7 = Boost
Where 62 = the blowers displacement
Ratio = the drive ratio
97.5 = half of the engine’s displacement
14.7 = the assumed atmospheric absolute pressure
For example with the base SC kit
62 * 1.985 / 97.5 * 14.7 - 14.7 = 3.86 PSI
That 3.86 PSI boost is about correct with the base kit. Here it is with the HBP and stock crank:
62 * 2.168 / 97.5 * 14.7 - 14.7 = 5.57 PSI
Which, once again, is about right.
Now for UR pulley with the HBP:
62 * 1.746 / 97.5 * 14.7 - 14.7 = 1.62 PSI
IMO, it is better to stick with the stock crank pulley.
Just for fun, here are the numbers with the base SC pulley and the UR crank pulley:
62 * 1.599 / 97.5 * 14.7 - 14.7 = 0.25 PSI :o
When the UR crank pulley is used with the SC kit, the blower would be turned only slightly faster than the engine even with the HBP. So you would only be making about 1.6 PSI boost. This would give up about 30 - 35 WHP at this low of boost; or the majority of the gain the SC provides.
Here are the numbers for the Accessory Belt (in millimeters):
Stock Crank / Alternator Side
175 / 67 = 2.612 Ratio
UR Crank / Alternator Side
141 / 67 = 2.104 Ratio
Here are the numbers for the SC Belt:
Base Pulley / SC Pulley
76 / 100 = 0.76 Ratio
HBP / SC Pulley
83 / 100 = 0.83 Ratio
To determine the final ratio, multiply the two values. For example with the standard SC kit:
2.612 * 0.76 = 1.985
In this case the blower is turning 1.985 times faster than the engine. This can be directly correlated to boost since it is a positive displacement blower.
For another example, using the HBP and the stock crank:
2.612 * 0.83 = 2.168
Using the UR crank pulley and the HBP gives the following ratio:
2.104 * 0.83 = 1.746
Obviously slower than even the base SC pulley with the stock crank. Here is how you use these ratios to determine boost. Since it is a 62ci blower it moves that amount every revolution. But since this is a four stroke engine, a cylinder only ingests every other revolution, we have to take half of our displacement. Half of our 3.2L in cubic inches is about 97.5ci.
To calculate the theoretical boost you use the following formula:
62 * Ratio / 97.5 * 14.7 - 14.7 = Boost
Where 62 = the blowers displacement
Ratio = the drive ratio
97.5 = half of the engine’s displacement
14.7 = the assumed atmospheric absolute pressure
For example with the base SC kit
62 * 1.985 / 97.5 * 14.7 - 14.7 = 3.86 PSI
That 3.86 PSI boost is about correct with the base kit. Here it is with the HBP and stock crank:
62 * 2.168 / 97.5 * 14.7 - 14.7 = 5.57 PSI
Which, once again, is about right.
Now for UR pulley with the HBP:
62 * 1.746 / 97.5 * 14.7 - 14.7 = 1.62 PSI
IMO, it is better to stick with the stock crank pulley.
Just for fun, here are the numbers with the base SC pulley and the UR crank pulley:
62 * 1.599 / 97.5 * 14.7 - 14.7 = 0.25 PSI :o
#3
Suzuka Master
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Originally posted by typeR
what about the UR crank pulley that doesnt under drive made for the SC application just 6 lbs lighter weight
what about the UR crank pulley that doesnt under drive made for the SC application just 6 lbs lighter weight
This is just for the UR under drive crank pulley which is smaller than the stock crank pulley.
If it it the same size then the stock numbers would be used. I mainly spoke of boost which is independant of weight, just size.
#4
Three Wheelin'
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I always wondered, and was recently asked buy someone interested in the blower that has the UR underdrive pulley. By your numbers the UR underdrive crank pulley is 20% smaller, but the final boost difference is 93% less.
#5
Suzuka Master
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Yep, it is that multiple ratios and the heavy depepandance on the crank which play a part. But most importantly it is the aspect that the blower speed has to be greater than the engine speed by a good margin in order to make boost.
You need a minimum of 1.57 times the engine speed to make boost. If you are running the blower twice the engine speed and reduce this by 20%; you end up with a 1.6 ratio. That has changed the boost making potential, as you stated, 93%.
What a huge impact and it goes to show that small overall changes have a dramatic affect on boost.
You need a minimum of 1.57 times the engine speed to make boost. If you are running the blower twice the engine speed and reduce this by 20%; you end up with a 1.6 ratio. That has changed the boost making potential, as you stated, 93%.
What a huge impact and it goes to show that small overall changes have a dramatic affect on boost.
#7
Senior Moderator
Originally posted by scalbert
If it it the same size then the stock numbers would be used. I mainly spoke of boost which is independant of weight, just size.
If it it the same size then the stock numbers would be used. I mainly spoke of boost which is independant of weight, just size.
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#9
Senior Moderator
Originally posted by scalbert
I understand and do appreciate the help and insight.
I understand and do appreciate the help and insight.
#10
Suzuka Master
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I can't say for sure. The SC would put an additional load on the belt drive system which was never accounted for. I don't think it would be an issue though.
#11
Parting out 02 Type S :(
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scalbert, thank you for clearing this topic up. i called comptech and UR, both said the boost would be so low that it would defeat the purpose of the SC
#14
THE J35A2...
Originally Posted by Accord_V6_400m
This thread has been brought to my attention so I thought I would do the same for everyone by bumping it
#15
But I just got here
iTrader: (1)
Bringing back this old thread because I have a question about the supercharger and crank pulley. I have the UR underdrive crank pulley and am getting the supercharger installed tomorrow. Can you change the crank pulley without having to remove the supercharger? I was going to order the UR stock diameter pulley and get it put in later this week.
#16
Originally Posted by Nitin
Bringing back this old thread because I have a question about the supercharger and crank pulley. I have the UR underdrive crank pulley and am getting the supercharger installed tomorrow. Can you change the crank pulley without having to remove the supercharger? I was going to order the UR stock diameter pulley and get it put in later this week.
#18
Former Sponsor
iTrader: (1)
Originally Posted by Nitin
Bringing back this old thread because I have a question about the supercharger and crank pulley. I have the UR underdrive crank pulley and am getting the supercharger installed tomorrow. Can you change the crank pulley without having to remove the supercharger? I was going to order the UR stock diameter pulley and get it put in later this week.
#19
4drs just wanna have fun!
iTrader: (1)
Took the liberity and calculated some boost levels for each pulley should someone upgrade to the MP90 unit Pretty interesting stuff.
UR Crank pulley/ Alternator Side
141 / 67 = 2.104 Ratio
Planning on running these ratios:
Stock Crank / Alternator Side
175 / 67 = 2.612 Ratio
3.0V6 base pulley (2.83")
71.9/100=0.719 Ratio
Base Pulley(3.0") / SC Pulley
76.2 / 100 = 0.762 Ratio
HBP (3.28") / SC Pulley
83.3 / 100 = 0.833 Ratio
Second final ratio is using the UR S crank pulley with identical alt. pulleys
2.83" pulley 2.612 * 0.719 = 1.878/1.51 = 2.85psi / MP90:10.78/ MP90+UR: 5.79
3.00" pulley 2.612 * 0.762 = 1.990/1.60 = 3.90psi / MP90 12.30 / MP90+UR 7.01
3.28" pulley 2.612 * 0.833 = 2.176/1.75 = 5.64psi / MP90 14.83 / MP90+UR 9.08
UR Crank pulley/ Alternator Side
141 / 67 = 2.104 Ratio
Planning on running these ratios:
Stock Crank / Alternator Side
175 / 67 = 2.612 Ratio
3.0V6 base pulley (2.83")
71.9/100=0.719 Ratio
Base Pulley(3.0") / SC Pulley
76.2 / 100 = 0.762 Ratio
HBP (3.28") / SC Pulley
83.3 / 100 = 0.833 Ratio
Second final ratio is using the UR S crank pulley with identical alt. pulleys
2.83" pulley 2.612 * 0.719 = 1.878/1.51 = 2.85psi / MP90:10.78/ MP90+UR: 5.79
3.00" pulley 2.612 * 0.762 = 1.990/1.60 = 3.90psi / MP90 12.30 / MP90+UR 7.01
3.28" pulley 2.612 * 0.833 = 2.176/1.75 = 5.64psi / MP90 14.83 / MP90+UR 9.08
#21
Blown is Best
Originally Posted by Accord_V6_400m
Took the liberity and calculated some boost levels for each pulley should someone upgrade to the MP90 unit Pretty interesting stuff.
UR Crank pulley/ Alternator Side
141 / 67 = 2.104 Ratio
Planning on running these ratios:
Stock Crank / Alternator Side
175 / 67 = 2.612 Ratio
3.0V6 base pulley (2.83")
71.9/100=0.719 Ratio
Base Pulley(3.0") / SC Pulley
76.2 / 100 = 0.762 Ratio
HBP (3.28") / SC Pulley
83.3 / 100 = 0.833 Ratio
Second final ratio is using the UR S crank pulley with identical alt. pulleys
2.83" pulley 2.612 * 0.719 = 1.878/1.51 = 2.85psi / MP90:10.78/ MP90+UR: 5.79
3.00" pulley 2.612 * 0.762 = 1.990/1.60 = 3.90psi / MP90 12.30 / MP90+UR 7.01
3.28" pulley 2.612 * 0.833 = 2.176/1.75 = 5.64psi / MP90 14.83 / MP90+UR 9.08
UR Crank pulley/ Alternator Side
141 / 67 = 2.104 Ratio
Planning on running these ratios:
Stock Crank / Alternator Side
175 / 67 = 2.612 Ratio
3.0V6 base pulley (2.83")
71.9/100=0.719 Ratio
Base Pulley(3.0") / SC Pulley
76.2 / 100 = 0.762 Ratio
HBP (3.28") / SC Pulley
83.3 / 100 = 0.833 Ratio
Second final ratio is using the UR S crank pulley with identical alt. pulleys
2.83" pulley 2.612 * 0.719 = 1.878/1.51 = 2.85psi / MP90:10.78/ MP90+UR: 5.79
3.00" pulley 2.612 * 0.762 = 1.990/1.60 = 3.90psi / MP90 12.30 / MP90+UR 7.01
3.28" pulley 2.612 * 0.833 = 2.176/1.75 = 5.64psi / MP90 14.83 / MP90+UR 9.08
#23
4drs just wanna have fun!
iTrader: (1)
Originally Posted by Allout
Is upgrading to the MP90 even possible without serious fabrication?
PLus Doug from Hondata always thought the MP62 was small for our cars, im split on it, would be nice to work out and perfect however
#24
Blown is Best
Originally Posted by Accord_V6_400m
I've been going around to some blower shops and asking around, imaginegetting another half liter out of each revolution of the rotors
PLus Doug from Hondata always thought the MP62 was small for our cars, im split on it, would be nice to work out and perfect however
PLus Doug from Hondata always thought the MP62 was small for our cars, im split on it, would be nice to work out and perfect however
#26
Blown is Best
Whipple Supercharger is in my town. I should go visit them and see what they think. They tuned the Ford GT of a guy I know and it's putting down over 1000HP on 91 octane and still meets CA Smog.
#28
4drs just wanna have fun!
iTrader: (1)
Originally Posted by Allout
Whipple Supercharger is in my town. I should go visit them and see what they think. They tuned the Ford GT of a guy I know and it's putting down over 1000HP on 91 octane and still meets CA Smog.
Thats pretty impressive, I bet the GT is rated at EV (Emission Vehicle)
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