As the title says, after a long planning I installed variable intake manifold form 156 1,8TS to 147 1,6TS. Actually I installed it twice. The first try few weeks ago was not successful and after hours of fiddling with the engine I noticed that variable intake uses different vacuum pipe to brake cylinder as the 1,6 manifold. Actually if somebody eventually thinks about this mod, this is the only extra part that is needed (worth 15 EUR).
The installation is not very complicated, except one bolt. You can see it red marked on the B/W picture in attachment. It is almost impossible to reach if you don’t want to strip the cylinder head. You need somebody with slim and long arm to lie on the engine and pass his hand from the throttle body side, under the manifold and side by side with cylinder block to the bolt. It can be touched with a finger from under power steering container, but there is no space for any tool form this side.
Actually all the careful disassembly is about 1-1,5 hours, the assembly is another 1-1,5 hour but this one bolt can take 2-4 hours to unscrew and screw back :rant:
The intake length is operated by a solenoid visible on the 3rd picture. It is a simple vacuum piston opened at certain revs and thus operating the manifold. Normally it is in "short" position, when you connect +12V to the solenoid pins it opens lets vacuum pressure on the piston and switches the manifold to "long" position. 1,8 and 2,0 TS operate this way:
idle - 2800 rpm - short
2800 - 5200 rpm - long
5200 – rev. limiter - short
This means you just need to lead +12V to the solenoid between 2800 and 5200 rpm. To do this I purchased a special rpm based switch.
RPM Activated Switches, PN 8950, PN 8956, PN 8957
However I didn’t manage to connect it yet, it requires connection to negative coil terminal but it doesn’t work for me. It seems to expect central coil pack with distributor for all cylinders (my guess). However Alfa has separate coils for each cylinder and it seems it can’t work with this signal (1/4 of the expected impulses???). I am in contact with MSD to solve this.
If you have any suggestion how to make/buy some circuit to operate the solenoid (connect it to 12V between 2800-5200 revs) please let me know. Any help is much appreciated!!!
Results so far (switching not working yet):
Car feels very different. It has much more torque between 1500 - 3000 rpm. It amazed me, but I can feel more power gain as after the remap. Between 3000 - 5500 I can’t comment anything. I don’t think I gained something but I would be very careful to comment any torque loss. I drove the car only for 30 km so far, but in the middle range it feels unchanged. In the range 6000-7000 there is a dramatic change. It always revved nicely, but what I can feel now surprises me. I have to pay attention not to hit rev limiter all the times. It pulls from 6500-7000 very strongly even in 4th gear what was not so natural before.
Car seems to breathe more easily. The new intake plenum has much larger volume. Actually the plenum intake after the throttle has about 25 percent larger diameter. I forgot to take pictures side by side, but 1,6 manifold is really restricted with its intake diameter. The ports to the cylinders alone are the same size.
Engine note has changed a lot as well, it sounds different, but I can’t describe it precisely where the change lies. Except some resonation in the exhaust (???) I started to hear around 3000 rpm
I am very impressed by the change, even though the switching doesn’t work yet. I don’t think that the manifold alone would have so big effect on a stock car, but as I have it custom remapped, custom exhaust manifold and removed pre-cats I think that only now my mods are starting to work together.
I hope that in 1-2 months I will have solved the switching problem and will have fitted my 200 cell racing cat with custom stainless steel center part of exhaust (delayed because money issue, but parts already arrived
).
The installation is not very complicated, except one bolt. You can see it red marked on the B/W picture in attachment. It is almost impossible to reach if you don’t want to strip the cylinder head. You need somebody with slim and long arm to lie on the engine and pass his hand from the throttle body side, under the manifold and side by side with cylinder block to the bolt. It can be touched with a finger from under power steering container, but there is no space for any tool form this side.
Actually all the careful disassembly is about 1-1,5 hours, the assembly is another 1-1,5 hour but this one bolt can take 2-4 hours to unscrew and screw back :rant:
The intake length is operated by a solenoid visible on the 3rd picture. It is a simple vacuum piston opened at certain revs and thus operating the manifold. Normally it is in "short" position, when you connect +12V to the solenoid pins it opens lets vacuum pressure on the piston and switches the manifold to "long" position. 1,8 and 2,0 TS operate this way:
idle - 2800 rpm - short
2800 - 5200 rpm - long
5200 – rev. limiter - short
This means you just need to lead +12V to the solenoid between 2800 and 5200 rpm. To do this I purchased a special rpm based switch.
RPM Activated Switches, PN 8950, PN 8956, PN 8957
However I didn’t manage to connect it yet, it requires connection to negative coil terminal but it doesn’t work for me. It seems to expect central coil pack with distributor for all cylinders (my guess). However Alfa has separate coils for each cylinder and it seems it can’t work with this signal (1/4 of the expected impulses???). I am in contact with MSD to solve this.
If you have any suggestion how to make/buy some circuit to operate the solenoid (connect it to 12V between 2800-5200 revs) please let me know. Any help is much appreciated!!!
Results so far (switching not working yet):
Car feels very different. It has much more torque between 1500 - 3000 rpm. It amazed me, but I can feel more power gain as after the remap. Between 3000 - 5500 I can’t comment anything. I don’t think I gained something but I would be very careful to comment any torque loss. I drove the car only for 30 km so far, but in the middle range it feels unchanged. In the range 6000-7000 there is a dramatic change. It always revved nicely, but what I can feel now surprises me. I have to pay attention not to hit rev limiter all the times. It pulls from 6500-7000 very strongly even in 4th gear what was not so natural before.
Car seems to breathe more easily. The new intake plenum has much larger volume. Actually the plenum intake after the throttle has about 25 percent larger diameter. I forgot to take pictures side by side, but 1,6 manifold is really restricted with its intake diameter. The ports to the cylinders alone are the same size.
Engine note has changed a lot as well, it sounds different, but I can’t describe it precisely where the change lies. Except some resonation in the exhaust (???) I started to hear around 3000 rpm
I am very impressed by the change, even though the switching doesn’t work yet. I don’t think that the manifold alone would have so big effect on a stock car, but as I have it custom remapped, custom exhaust manifold and removed pre-cats I think that only now my mods are starting to work together.
I hope that in 1-2 months I will have solved the switching problem and will have fitted my 200 cell racing cat with custom stainless steel center part of exhaust (delayed because money issue, but parts already arrived
).
