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It is worth noting that both the "Boost" and "Boost with headers" categories are not exact numbers and WILL vary from vehicle to vehicle. It is also worth mentioning that vehicles with Belt wrap Kits will see an increase in boost pressure by about 1psi depending on the pulley setup.
This chart is only intended to be a guideline for supercharger pulley vs crank pulley. Please Remember to monitor your vehicles response to each modification as each vehicle will be different.
Hopefully you find this information useful and beneficial as you continue your builds. And be sure to checkout VRPspeed.com for the largest variety of pulley sizes available.
Thank you
Last edited by VictoryRoadPerformance; 12-13-2017 at 09:01 PM.
I am unfamiliar with how M113K are designed (or any modern S\C setup), but always found this bit confusing:
S\C is driven from the crank
S\C speed is therefore a linear function of the engine speed
Should boost PSI therefore become a linear function of the RPM until it hits peak at redline?
OR, is the supercharger overdriven and peaks way sooner and the car simply maintains correct boost level using some sort of pressure release mechanism?
Reason I ask is my manifold air pressure readouts on the Torque app peak early and plateau for more or less a constant boost level across a band of RPM.
EDIT: In other words, is the M113K setup the blue or the red line?
Its also worth noting that a 280 part number blower will see slightly lower numbers than the slightly overdriven 580 or 080 part number blowers.
To answer your question jumph4x yes your supercharger is a twin screws type compressor .... like the kenny bell the one with the blue line is a centrifugal type like a paxton or am vortech that are more of a belt driven turbo and achieve peak boost only at upper rpms.
I am unfamiliar with how M113K are designed (or any modern S\C setup), but always found this bit confusing:
S\C is driven from the crank
S\C speed is therefore a linear function of the engine speed
Should boost PSI therefore become a linear function of the RPM until it hits peak at redline?
OR, is the supercharger overdriven and peaks way sooner and the car simply maintains correct boost level using some sort of pressure release mechanism?
Reason I ask is my manifold air pressure readouts on the Torque app peak early and plateau for more or less a constant boost level across a band of RPM.
EDIT: In other words, is the M113K setup the blue or the red line?
We have a bypass valve that releases boost. While you are correct in stating it is linear the bypass affects that. Other things that affect it are slippage and fueling.
Should boost PSI therefore become a linear function of the RPM until it hits peak at redline?
No because the engine rpm is obviously increasing at the same rate and using that increased air at the same rate the supercharger is producing it. The reason you don't get full boost at very low rpm is because air slips past the rotor lobes and its not until about 1500rpm it is up to full efficiency. Roots and twin screw are very different to centrifugal in this regard with fixed internal compression ratio. Supercharged by corky bell is a great read, highly recommend it.
Its also worth noting that a 280 part number blower will see slightly lower numbers than the slightly overdriven 580 or 080 part number blowers.
To answer your question jumph4x yes your supercharger is a twin screws type compressor .... like the kenny bell the one with the blue line is a centrifugal type like a paxton or am vortech that are more of a belt driven turbo and achieve peak boost only at upper rpms.
Originally Posted by seanol
We have a bypass valve that releases boost. While you are correct in stating it is linear the bypass affects that. Other things that affect it are slippage and fueling.
Originally Posted by tw2
No because the engine rpm is obviously increasing at the same rate and using that increased air at the same rate the supercharger is producing it. The reason you don't get full boost at very low rpm is because air slips past the rotor lobes and its not until about 1500rpm it is up to full efficiency. Roots and twin screw are very different to centrifugal in this regard with fixed internal compression ratio. Supercharged by corky bell is a great read, highly recommend it.
No problem, basically roots doesn't compress the air internally it just pumps it into the restricted manifold to make boost. The other two compress the air before it exits the supercharger. The twin screw and roots take a certain specific amount of air in with each revolution, the centrifugal varies widely including air occasionally going backwards trough the unit if the throttle body is suddenly closed.
can anyone tell me what the difference are between the 280, 580 and 080 SC?
thanks
The 280 part number supercharger is identical in every way to the 580 an 080 except they are overdriven 4.86% over the earlier 03 to 04 280 model number the 580 an 080 came on late 04s 05 an 06 from what ive seen. I had a 280 with 140k on my 03 an came across a 15k mileage 580 an stole it for the price i paid an it did make about .8psi more with same setup
The 280 part number supercharger is identical in every way to the 580 an 080 except they are overdriven 4.86% over the earlier 03 to 04 280 model number the 580 an 080 came on late 04s 05 an 06 from what ive seen. I had a 280 with 140k on my 03 an came across a 15k mileage 580 an stole it for the price i paid an it did make about .8psi more with same setup
Have folks actually compared how much boost they're actually making vs this chart? I'm running stock crank, 82mm TB, 83mm pulley, and ARH LT headers with 200 cell cats and have never seen anywhere close to 12.67PSI of boost. I think the best I've ever seen was like 10.9 or so.
Have folks actually compared how much boost they're actually making vs this chart? I'm running stock crank, 82mm TB, 83mm pulley, and ARH LT headers with 200 cell cats and have never seen anywhere close to 12.67PSI of boost. I think the best I've ever seen was like 10.9 or so.
There are a number of factors that determine acctual boost pressure, This is more of a reference to determine where you will be based off of where you are now. Altitude, Wether you have ported parts, or exhaust all makes a difference. You are about right with Longtubes,.
It represents how much your supercharger will overheat causing heatsoak and reduce the power of the car based on overspinning the supercharger and overwhelming the intercooler. Green is good and red is bad..
Car dumps fuel and reduces timing advance based on the intake air temperature
12-13-2017, 04:41 PM
