- Joined
- Apr 27, 2012
- Points
- 100
M54B30 Intake manifold
- Thread starter Southernboy
- Start date
Hello,
I also made the change a few years ago, but I was a little disappointed...
I ran the car on the power bench and it had 206hp from the original, except for a direct intake.
After the modification, the direct intake, which made a terrible noise with the 2.8 manifold, was a lot less...
I didn't feel much difference in power, maybe a bit better up top...
And indeed, I took the car back to the power bench and it was 204hp...
After deprogramming, it was 216hp...
So, instead of gaining power, I lost power...
How do you explain the loss of power and the loss of noise from the direct intake?
I also made the change a few years ago, but I was a little disappointed...
I ran the car on the power bench and it had 206hp from the original, except for a direct intake.
After the modification, the direct intake, which made a terrible noise with the 2.8 manifold, was a lot less...
I didn't feel much difference in power, maybe a bit better up top...
And indeed, I took the car back to the power bench and it was 204hp...
After deprogramming, it was 216hp...
So, instead of gaining power, I lost power...
How do you explain the loss of power and the loss of noise from the direct intake?
- Joined
- Apr 27, 2012
- Points
- 100
If you consider a simple experiment.
Blowing down a narrow diameter pipe of x length requires more effort than a larger diameter pipe of the same length.
If exactly the same volume of air is forced through both, the velocity of the air flow through the narrower gauge pipe will be higher than through the larger pipe.
The difference will be that a higher pressure is required to get that volume through the narrow gauge pipe vs the pressure required to get it through a larger diameter pipe.
Since the size of the throttle body in the modification isn't altered, one must assume the same velocity and volume of air is passing through it as demanded by the engine.
The next point is the unknown. What happens to the air as it exits the end of a narrower gauge pipe when the exact same air volume enters a smaller restricted space vs a larger space volume. It would seem common sense that the same volume of air entering a smaller space would be at higher compression than if it entered a larger volume space,
Next, given the above, it would seem sensible to assume the pressure wave is changed with a consequent effect when it arrives at the intake valve.
I will surmise, there is less velocity where the same volume of air passes through the same diameter pipe but exhausts into a larger chamber area before arriving at the intake valve. Thus the pressure wave and frequency being altered may not force as much air in through the intake vale in the same time limits that the valve is open.
If you increase the "open" time of the intake valve, this may compensate for the drop in pressure / velocity at the valve, but the volume of air available to enter through the valve is unchanged since x volume is all that can pass through the size of the throttle body given the demand by the engine at any specific rpm.
Next, the DISA. A larger DISA will direct more air in a given direction by virtue of the size of the flap. But it can only direct more of the same volume available. Also, it is directing that volume at a lower velocity and pressure given that the incoming volume is allowed to expand into a larger volume space in the manifold.
The difference between the OEM and M54 manifolds is in the runner length and the volume just inside the manifold where the throttle body is attached to it. Other than those two aspects, the only other possible difference may be in the runner internal diameter of the M54. If it is larger than the OEM, the pressure and velocity wave is altered.The fact that the DISA is directing more of the given volume towards the required runner (s) may minimise the drop in pressure as compared to the OEM DISA.
It would seem that the minor discrepancy of 2HP (204 vs 206) you have recorded indicates that there is more potential benefit in engineering the OEM runners to match the cylinder head intake ports and retaining pressure / velocity wave in the OEM setup.
If one could fit a larger throttle body as well as the larger M54 manifold capacity and DISA. I would hazard one would experience a significant gain in performance.
It must be emphasised that, the cc volume of the motor will only draw in a corresponding volume of air. A larger throttle body and manifold will only provide less restriction for that same volume being demanded. Also, the pressure will respectively drop since the fixed volume demanded by the cc size of the motor is the same, but flowing through a larger volume space. The negative effort placed on each piston stroke drawing the air in will be lowered since the available volume of the manifold and throttle body is less restrictive which may provide better performance but not automatically greater HP.
In conclusion it may be said that the M54 manifold provides a better performance, but not increased HP. Ultimately, the throttle body is a restriction due to it's size. but this can also be said of the size of the MAF body too. A 2.8 litre motor can only draw in x amount of air. De-restricting that process decreases the effort on each intake stroke of each piston. The only way to get more air into the same cc capacity is by forcing it in by use of turbo or supercharger which simply put increases air pressure.
Blowing down a narrow diameter pipe of x length requires more effort than a larger diameter pipe of the same length.
If exactly the same volume of air is forced through both, the velocity of the air flow through the narrower gauge pipe will be higher than through the larger pipe.
The difference will be that a higher pressure is required to get that volume through the narrow gauge pipe vs the pressure required to get it through a larger diameter pipe.
Since the size of the throttle body in the modification isn't altered, one must assume the same velocity and volume of air is passing through it as demanded by the engine.
The next point is the unknown. What happens to the air as it exits the end of a narrower gauge pipe when the exact same air volume enters a smaller restricted space vs a larger space volume. It would seem common sense that the same volume of air entering a smaller space would be at higher compression than if it entered a larger volume space,
Next, given the above, it would seem sensible to assume the pressure wave is changed with a consequent effect when it arrives at the intake valve.
I will surmise, there is less velocity where the same volume of air passes through the same diameter pipe but exhausts into a larger chamber area before arriving at the intake valve. Thus the pressure wave and frequency being altered may not force as much air in through the intake vale in the same time limits that the valve is open.
If you increase the "open" time of the intake valve, this may compensate for the drop in pressure / velocity at the valve, but the volume of air available to enter through the valve is unchanged since x volume is all that can pass through the size of the throttle body given the demand by the engine at any specific rpm.
Next, the DISA. A larger DISA will direct more air in a given direction by virtue of the size of the flap. But it can only direct more of the same volume available. Also, it is directing that volume at a lower velocity and pressure given that the incoming volume is allowed to expand into a larger volume space in the manifold.
The difference between the OEM and M54 manifolds is in the runner length and the volume just inside the manifold where the throttle body is attached to it. Other than those two aspects, the only other possible difference may be in the runner internal diameter of the M54. If it is larger than the OEM, the pressure and velocity wave is altered.The fact that the DISA is directing more of the given volume towards the required runner (s) may minimise the drop in pressure as compared to the OEM DISA.
It would seem that the minor discrepancy of 2HP (204 vs 206) you have recorded indicates that there is more potential benefit in engineering the OEM runners to match the cylinder head intake ports and retaining pressure / velocity wave in the OEM setup.
If one could fit a larger throttle body as well as the larger M54 manifold capacity and DISA. I would hazard one would experience a significant gain in performance.
It must be emphasised that, the cc volume of the motor will only draw in a corresponding volume of air. A larger throttle body and manifold will only provide less restriction for that same volume being demanded. Also, the pressure will respectively drop since the fixed volume demanded by the cc size of the motor is the same, but flowing through a larger volume space. The negative effort placed on each piston stroke drawing the air in will be lowered since the available volume of the manifold and throttle body is less restrictive which may provide better performance but not automatically greater HP.
In conclusion it may be said that the M54 manifold provides a better performance, but not increased HP. Ultimately, the throttle body is a restriction due to it's size. but this can also be said of the size of the MAF body too. A 2.8 litre motor can only draw in x amount of air. De-restricting that process decreases the effort on each intake stroke of each piston. The only way to get more air into the same cc capacity is by forcing it in by use of turbo or supercharger which simply put increases air pressure.
Yes, but I could read that those who had made the modification had felt an increase in power, which was sometimes checked on the power bench.
This modification is apparently recognized and gives good results.
Where could the fact that I don't gain anything at all or even lose anything come from?
What about noise loss?
Could this also be due to the different length and/or width of the supply ducts?
This modification is apparently recognized and gives good results.
Where could the fact that I don't gain anything at all or even lose anything come from?
What about noise loss?
Could this also be due to the different length and/or width of the supply ducts?
- Joined
- Apr 27, 2012
- Points
- 100
It is possible you may have got an incorrect read when you tested after the mod.
Also, as I and others have said, they get the impression of better power at higher rpm, but not at low rpm.
The BMW manifold and DISA system is designed to provide a modicum of forced induction by directing air volume towards specific pistons in greater than atmospheric pressure. This results in more HP.
With the larger M54 manifold DISA it is possible that this effect is increased and therefor a greater forced induction is the result.
Even using the OEM DISA / manifold setup, the DISA doesn't come into action under 3000 rpm.
My contention is that if the OEM manifold runners were to be engineered to the D shape of the cylinder head, it may result in similar gains as using an M54 manifold, with the exception of the larger DISA action.
If you still have your OEM manifold, it is a very easy bit of work to re-shape the runners to a D shape simply by using a rough square shape file to grind away the corners. In any event, the interior shape of both the OEM and M54 runners is oval and as on the M54 runners it flares out to the D shape. This means that it is only within 50mm of the mating points between runner and cylinder head that the differences occur.
Therefor it's the larger DISA flap which is making the difference at over 3000 rpm.
I have the M54 intake cam fitted. This has made the biggest difference in combination with the M54 manifold. the extra "open" time of the intake valves and also the higher lift it provides, allows airflow into the cylinder to be less restricted by the valve being opened wider and longer. The resultant power gain is significant. What remains for me to do is to have the fuel supply - ie the injector "open" time re-programmed to compensate for what is currently a "lean" mixture on my motor.
Obviously this will mean a higher fuel consumption, but a corresponding increase in power. I guess performance costs and costs and costs..
Also, as I and others have said, they get the impression of better power at higher rpm, but not at low rpm.
The BMW manifold and DISA system is designed to provide a modicum of forced induction by directing air volume towards specific pistons in greater than atmospheric pressure. This results in more HP.
With the larger M54 manifold DISA it is possible that this effect is increased and therefor a greater forced induction is the result.
Even using the OEM DISA / manifold setup, the DISA doesn't come into action under 3000 rpm.
My contention is that if the OEM manifold runners were to be engineered to the D shape of the cylinder head, it may result in similar gains as using an M54 manifold, with the exception of the larger DISA action.
If you still have your OEM manifold, it is a very easy bit of work to re-shape the runners to a D shape simply by using a rough square shape file to grind away the corners. In any event, the interior shape of both the OEM and M54 runners is oval and as on the M54 runners it flares out to the D shape. This means that it is only within 50mm of the mating points between runner and cylinder head that the differences occur.
Therefor it's the larger DISA flap which is making the difference at over 3000 rpm.
I have the M54 intake cam fitted. This has made the biggest difference in combination with the M54 manifold. the extra "open" time of the intake valves and also the higher lift it provides, allows airflow into the cylinder to be less restricted by the valve being opened wider and longer. The resultant power gain is significant. What remains for me to do is to have the fuel supply - ie the injector "open" time re-programmed to compensate for what is currently a "lean" mixture on my motor.
Obviously this will mean a higher fuel consumption, but a corresponding increase in power. I guess performance costs and costs and costs..
- Joined
- Apr 27, 2012
- Points
- 100
Regarding the noise loss you mentioned... this may be due to the velocity of airflow through the filter.
The same volume of air is passing through, but the velocity has dropped due to the larger M54 manifold where it experiences an expansion as it enters a larger volume space. The de-restriction as compared to the OEM manifold in that respect may account for the reduction in noise.
The same volume of air is passing through, but the velocity has dropped due to the larger M54 manifold where it experiences an expansion as it enters a larger volume space. The de-restriction as compared to the OEM manifold in that respect may account for the reduction in noise.
- Joined
- Apr 27, 2012
- Points
- 100
You have possibly just resolved that by mentioning the radiator fan.. is it possible that it was responsible for the excessive noise ??
Alternately, as I mentioned above in my last message...
Alternately, as I mentioned above in my last message...
Sorry, my English isn't perfect and I use a translator...
As for the noise, it's just the opposite...
When I had the original intake manifold, the direct intake made a nice loud noise.
Since I put in the M54 intake manifold, the intake noise is much quieter...
As for the noise, it's just the opposite...
When I had the original intake manifold, the direct intake made a nice loud noise.
Since I put in the M54 intake manifold, the intake noise is much quieter...
- Joined
- Apr 27, 2012
- Points
- 100
Regarding the noise loss you mentioned... this may be due to the velocity of airflow through the filter.
The same volume of air is passing through, but the velocity has dropped due to the larger M54 manifold where it experiences an expansion as it enters a larger volume space. The de-restriction as compared to the OEM manifold in that respect may account for the reduction in noise.
The same volume of air is passing through, but the velocity has dropped due to the larger M54 manifold where it experiences an expansion as it enters a larger volume space. The de-restriction as compared to the OEM manifold in that respect may account for the reduction in noise.
- Joined
- Apr 27, 2012
- Points
- 100
Before you put it back, do the re-shaping of the manifold runners to D shape. This will overcome the current OEM restriction.