Why did volvo remove the variable intake manifold?

[dikidera]

During the day I am reverse engineering Denso, during the night researching this. Today I reached an epiphany. It is small, but related to the FCP car. In the dyno video

they are opening the short runners at 4840RPM, Recall in the original Volvo design(or it was that box mod) they open the flaps earlier at 4100rpm, I think this is an important design consideration, it is possible the short runners are designed for resonance at or around 4500rpm. By missing this RPM mark they made 140 wheel horsepower not at 5900-6000rpm but at 6500 rpm. This does not mean that it would've made more power had they opened it at 4100rpm, though you can never know. In the video they do mention two key things, volume and flow. There are some caveats, which volume? There is port volume AND plenum volume. Perhaps the issue is more about port volume, the original manifold has a big runner, whereas the variable runner manifold has probably two smaller cross-sectional area ports.

In the end they did go with ITBs so neither manifolds were up to the task.

I will at least try on the VIS manifold on my RN engine, however I have two issues. One is that the RN(facelift) manifolds have a 70mmx55mm bolt hole pattern, whereas my magnetti marelli is 70x70mm. I could be off a bit, but the point I am trying to make is that the Magnetti Marelli TB will not fit as-is. I will have to weld two ears where the bolt will be. Stick welding aluminum does not sound easy. I do not plan to take off my MM TB to test-fit it, I just hope the throttle opening actually fits one side ok.

Second issue is that the RN engine NA manifolds have a slant to the Manifold TB opening in order for the TB intake hose to fit properly. I do hope it will not be an issue.

[V50M66]

During the day I am reverse engineering Denso, during the night researching this. Today I reached an epiphany. It is small, but related to the FCP car. In the dyno video

they are opening the short runners at 4840RPM, Recall in the original Volvo design(or it was that box mod) they open the flaps earlier at 4100rpm, I think this is an important design consideration, it is possible the short runners are designed for resonance at or around 4500rpm. By missing this RPM mark they made 140 wheel horsepower not at 5900-6000rpm but at 6500 rpm. This does not mean that it would've made more power had they opened it at 4100rpm, though you can never know. In the video they do mention two key things, volume and flow. There are some caveats, which volume? There is port volume AND plenum volume. Perhaps the issue is more about port volume, the original manifold has a big runner, whereas the variable runner manifold has probably two smaller cross-sectional area ports.

In the end they did go with ITBs so neither manifolds were up to the task.

I will at least try on the VIS manifold on my RN engine, however I have two issues. One is that the RN(facelift) manifolds have a 70mmx55mm bolt hole pattern, whereas my magnetti marelli is 70x70mm. I could be off a bit, but the point I am trying to make is that the Magnetti Marelli TB will not fit as-is. I will have to weld two ears where the bolt will be. Stick welding aluminum does not sound easy. I do not plan to take off my MM TB to test-fit it, I just hope the throttle opening actually fits one side ok.

Second issue is that the RN engine NA manifolds have a slant to the Manifold TB opening in order for the TB intake hose to fit properly. I do hope it will not be an issue.

You will be going through A LOT of work for what is going to be a power loss. How do you plan to control the VVIS actuator on ME7?

[dikidera]

It's not really a lot of work at all. And so far the cost has been less than $50. What would be expensive is a custom exhaust header. Also it's not ME7, it is Denso and I do not plan to control the VVIS with it. I possibly could, but that would be actual hard work and my code would not conform to MISRA C standards.

Instead I planned to use an Arduino or something suitable.

Now as for the power loss, I am assuming you mean the bit where in the video they mention flow. I may have a solution for this. Also remember, my NA engine is the same engine(almost) as the one from the 850 glt, the difference being camshafts. I cannot lose power. And even if I did, it's all a matter of simply going back to the original runner.

It's also not expensive, since I spent $10 on the VIS manifold, whereas I've spent hundreds of just to flush the ATF of my transmission. I am also due coils, which are another $100. So in comparison it's a cheap experiment and it's also fun, gives me a sense of accomplishment.

[volvolugnut]

Sometimes we do things for the experience of doing them.
volvolugnut

[dikidera]

Yes that is true. And in the end, even if the end result was worse than anticipated, the experience along the way alone would make up for everything.

In any case, it will take me some time to figure out some things.





Slowly, but surely.

Addendum:

There we go. Much better




Of course this is the easy part, for flow simulation I will have to get inside and start adding the geometry. That will take time.