Here's a little comparison on the Toyota AE82 Twin Cam GT from Sushi Express rally team : checking with PerfExpert the difference in torque and power between the original plenum and open velocity stacks.
To make this comparison reliable it was necessary to proceed as following :
- Always stop the car at the same mark on the road before pressing the START button,
- Always WOT at the same mark on the road,
- Perform all measurements in the same direction of travel,
- Be sure to follow the PerfExpert measurement procedures (phone calibration performed, impeccable phone mounting, weak wind, free road, lift windows...)
- If the car remained parked for a while then drive it a few minutes at medium speed to cool down the engine bay. This is to always similar engine bay temperature for all measurements,
- For each setup (plenum or open stacks), perform at least two measurements having less than 2% deviation to confirm their reliability. Indeed non-repeatable measurements (differences of more than 2%) could reflect a poor phone fixation or poor conditions (road, wind, engine bay temperature...).
![Toyota Corolla TwinCam GT AE92 Toyota Corolla TwinCam GT AE92](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_auto/659196/ae82_s8fylo.jpg)
![4AGE 20V Blacktop with T3 open velocity stacks 4AGE 20V Blacktop with T3 open velocity stacks](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_auto/659196/open_stacks1_sfhpkd.jpg)
![Dyno result 4AGE 20V Blacktop with T3 open velocity stacks Dyno result 4AGE 20V Blacktop with T3 open velocity stacks](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_auto/659196/8a134909-5edf-4b0b-9388-e8f74b32c6f8_fki7j3.png)
![Dyno result 4AGE 20V Blacktop with T3 open velocity stacks Dyno result 4AGE 20V Blacktop with T3 open velocity stacks](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_auto/659196/3b873f26-dccf-4abf-844d-f1e365805e0c_xowxvf.png)
Here are the results with this setup :
- 159.6hp @ 7300rpm / 131.8Ft.Lb @ 5500rpm
- 159.1hp @ 7300rpm / 133.2Ft.Lb @ 5300rpm
![broken image](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_auto/659196/plenum_ulttcc.jpg)
![broken image](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_auto/659196/plenum1_zuoyjq.jpg)
![Dyno result 4AGE 20V Blacktop with T3 open velocity stacks Dyno result 4AGE 20V Blacktop with T3 open velocity stacks](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_auto/659196/1f3f26c1-bc7f-4f9c-b747-55621da2a1a9_v488oe.png)
![broken image](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_auto/659196/b6bda570-f991-4aa5-a55a-a9c7851b1b2e_a7xpqv.png)
Here are the results with this setup :
- 150.4hp @ 7200rpm / 128.2Ft.Lb @ 5200rpm
- 151.3hp @ 7200rpm / 130.4Ft.Lb @ 5200rpm
Conclusion
This shows a clear advantage of open stacks in power (more than 5%), and a slight advantage in Torque. But the most interesting is to see the curves comparison :
![Dyno comparison of stock intake vs open stacks on 4AGE 20V Blacktop Dyno comparison of stock intake vs open stacks on 4AGE 20V Blacktop](http://custom-images.strikinglycdn.com/res/hrscywv4p/image/upload/c_limit,fl_lossy,h_9000,w_1200,f_auto,q_auto/659196/7e96e615-30cf-416a-944f-14449458f2d5_teploz.png)
Note that with the plenum there is a little more torque under 5000rpm and less torque passed this rpm. So really, even if the open stacks give more torque maximum value, the plenum give a more torquey engine at low rpm.
A pity that we didn't have a 100% stock plenum (whose stacks are not cut) and the original airbox + filter. The comparison would have been even more interesting.
If you have questions, please leave a comment!