XR7 Dave
Registered User
It has been repeatedly brought up that certain blower applications are better than others for street performance, so I thought it might be of interest to compare two different blowers in similar applications and how they help the 3.8L SC motor make useable street power.
I specifically cut off both of these charts above 5200rpm for 2 reasons. 1) street performance is below 5200rpm 99% of the time, and 2) both applications were having issues with either belt slip or insufficient injector above that rpm.
Both charts are available in full if someone so desires but that is not the topic of discussion here in this thread.
The cars used for this comparison are both excellent runners and easy 12 second cars. Both engines exhibit decent street manners and could be considered daily drivers. Both motors have some "trick" parts with neither one having a significant advantage in terms of cylinder head flow or camshaft profile.
In the first case an MPII at 15% OD was used for one run and an MPIII with 20% OD used on the second pull. Some adjustment was made to compensate for an overly rich condition as you can see from the AF chart. Further adjustment of AFR and timing did not result in any more power so the final number could be considered an optimized tune for comparison purposes.
As the chart shows this netted a gain of 7.9rwhp (2.3%) and 18.5rwtq (4.7%).
In the second case an off the shelf Magnusen S-Port was used with 5% OD on the first pull and a total of 10% OD on the second one. No adjustments were made between pulls.
Net result was a gain of 5.7rwhp (1.7%) and 15.8rwtq (4.1%).
This means that with the MPIII conversion the motor had lost about 51% of the gain in torque it had netted earlier in the rpm range, and the S-Port had lost about 58.5% of it's torque increase by 5200rpm.
Discuss.
I specifically cut off both of these charts above 5200rpm for 2 reasons. 1) street performance is below 5200rpm 99% of the time, and 2) both applications were having issues with either belt slip or insufficient injector above that rpm.
Both charts are available in full if someone so desires but that is not the topic of discussion here in this thread.
The cars used for this comparison are both excellent runners and easy 12 second cars. Both engines exhibit decent street manners and could be considered daily drivers. Both motors have some "trick" parts with neither one having a significant advantage in terms of cylinder head flow or camshaft profile.
In the first case an MPII at 15% OD was used for one run and an MPIII with 20% OD used on the second pull. Some adjustment was made to compensate for an overly rich condition as you can see from the AF chart. Further adjustment of AFR and timing did not result in any more power so the final number could be considered an optimized tune for comparison purposes.
As the chart shows this netted a gain of 7.9rwhp (2.3%) and 18.5rwtq (4.7%).
In the second case an off the shelf Magnusen S-Port was used with 5% OD on the first pull and a total of 10% OD on the second one. No adjustments were made between pulls.
Net result was a gain of 5.7rwhp (1.7%) and 15.8rwtq (4.1%).
This means that with the MPIII conversion the motor had lost about 51% of the gain in torque it had netted earlier in the rpm range, and the S-Port had lost about 58.5% of it's torque increase by 5200rpm.
Discuss.