Velocity Stacks
- Thread starter Tony Cluedo
- Start date
For me its not about the hp gains anyway. It has to be about the sound, if it comes with a few more horses then that's a bonus.
If you were to apply a 15% loss of power to the wheels that would translate to around 370+ bhp. Even being generous and saying 10% would equate to around 355 bhp. That's not too bad is it?
I must be looking at this incorrectly? Torque is down on standard...
Cold air feed would also be a concern (emphasis on cold)
Air box/plenum also looks better to me
Stevo
Cold air feed would also be a concern (emphasis on cold)
Air box/plenum also looks better to me
Stevo
Smartbear said:Tony Cluedo said:
It depends on the model of m3, my neighbours m3 has about 430bhp!
Rob
Shame they weigh so much
stevo///m3 said:
You are, those are at the wheel figures.
I've met Pete at PSDesigns a while back, nice chap, and he gives a fairly good explanation of why it does work. http://www.psdesignsglobal.com/velocity-stacks-faq-s/
I'm not 100% convinced, but they do sound good!
Definitely some pros and cons to consider on this one
Although they sound great in the video, I'm sure this would drive you mad if you had to live with them.
As to any performance gains: if you datalog the engine RPMs during acceleration at WOT, on the same piece of tarmac in the same ambient conditions, as recorded by the ECU in the real world situation, you will be able to see how long it takes for the engine to get from, say, 2,500rpm to 7,500rpm, and compare. Personally, I doubt if the velocity stacks will show an improvement on the OEM air-intake system which benefits from an increase in ram air pressure with increase in speed.
As to any performance gains: if you datalog the engine RPMs during acceleration at WOT, on the same piece of tarmac in the same ambient conditions, as recorded by the ECU in the real world situation, you will be able to see how long it takes for the engine to get from, say, 2,500rpm to 7,500rpm, and compare. Personally, I doubt if the velocity stacks will show an improvement on the OEM air-intake system which benefits from an increase in ram air pressure with increase in speed.
just-right
Member
The OEM intake has velocity stacks and so does the CSL. In general a velocity stack serves two purposes.
One being to tune the resonance frequency of the intake system with the valve opening and closing. The initial depression in the intake tract would ideally be followed by a wave induced pressure rise which nears maximum just before closing. To achieve this a clear termination of the tract needs to occur in combination with a correctly tuned length.
The second benefit is to smooth the entry of air into the intake port and minimise the loss of energy in the flow. With this the local boundary layer grows less and yields a more uniform flow distribution in the port. Although with pipe flow a decent amount of lack of uniformity is always present.
The problem with the systems described here is on one side a rise in intake temperature. This is often underestimated and even just a increase in 10 degrees will cause a loss in power of 4% or so. The other problem is there will be no pressurisation / ram air of the intake system.
One being to tune the resonance frequency of the intake system with the valve opening and closing. The initial depression in the intake tract would ideally be followed by a wave induced pressure rise which nears maximum just before closing. To achieve this a clear termination of the tract needs to occur in combination with a correctly tuned length.
The second benefit is to smooth the entry of air into the intake port and minimise the loss of energy in the flow. With this the local boundary layer grows less and yields a more uniform flow distribution in the port. Although with pipe flow a decent amount of lack of uniformity is always present.
The problem with the systems described here is on one side a rise in intake temperature. This is often underestimated and even just a increase in 10 degrees will cause a loss in power of 4% or so. The other problem is there will be no pressurisation / ram air of the intake system.
just-right
Member
exdos said:
Overall based on my experience it will not increase performance. The intake tract looks a little bit shorter so peak power might be close or increase slightly. On top of that with a tune and some favourable dyno conditions it wouldn't take much to make it look attractive. Your real life test would be more representable but the conditions have to be equal.