Alfa Romeo Giulia Forum banner
1 - 20 of 31 Posts

·
Registered
Joined
·
160 Posts
Discussion Starter · #1 ·
For the gearheads out there, here's some stuff from the Service Manual on the 2.0L models that might be of interest:

1) The turbo intercooler is liquid cooled using a separate low temperature cooling system with an electric pump, dedicated reservoir, and front mounted radiator.

2) There are no conventional intake or exhaust manifolds. The turbo bolts directly to the cylinder head exhaust port and the intercooler bolts directly to the cylinder head intake port. The flow is split/combined internally in the head.

3) A single camshaft operates the 16 valve system. Exhaust valves are operated directly by the cam and have fixed timing. The intake valves use the "MultiAir" system for variable timing. (Google "MultiAir" for full description). There are also two balance shafts.

4) The camshaft is chain driven and the engine is an "interference" design (valves will hit the pistons if the chain breaks during operation).

5) Heat from a lube oil cooler is removed by engine coolant. A dedicated front mounted radiator cools the transmission oil.

6) Driving mode changes include steering force, braking feel, throttle response, turbo boost, shift speed, shift points (rpm), and stability control. Several other functions are affected for models with electronic differential, AWD, electronic shocks, etc.
 

·
Registered
2018 Q4 with Fiamenghi Ti exhaust, Race Mod, and Tecnico wheels.
Joined
·
7,729 Posts
Are the cam sprockets splined (or keyed) on? Some engines use a bolt-on clamp (this saves space and cost) that can spin and cause a valve train failure.

I wonder how well this multi-air system keeps its adjustment over time? I see that the exhaust valves are reliable bucket and shims, but the cam follower and hydraulic actuator scheme on the intake valve seems a little more questionable. The actuators appear to be a place for leaks to happen and a cam follower will wear faster than bucket-and-shim.

Too bad there is no adjust-ability of the exhaust valve timing, since fiddling with exhaust valve timing can greatly increase engine braking (crack the valve during the compression stroke, or open the valve late during the exhaust stroke). These being how Jakebrake and exhaust brake work, respectively. As the engine gets designed to be more efficient and spin more freely some way to get more engine back pressure (or maybe just bigger brakes?) seems like it will be necessary.

Its good to hear that there is an oil cooler. I presume that this is a water to oil heat exchange from your description (also a good arrangement).

I presume that the transmission has an oil to air heat exchanger. Does anybody have enough experience to know if transmission overheating problems are an issue with this 8speed transmission? Having once had an automatic transmission boil over, spew fluid onto a hot exhaust manifold, and catch the vehicle on fire, I'm a bit leary of automatic transmission heat build up.
 

·
Registered
Joined
·
75 Posts
Multiair is an electro-hydraulic valve actuation system, multiair engines are a hybrid between twincam and camless engines, they use electro-hydraulic actuation for the intake valves preserving a conventional cam for the exhaust valves.
 

·
Registered
Joined
·
160 Posts
Discussion Starter · #6 ·
Are the cam sprockets splined (or keyed) on? Some engines use a bolt-on clamp (this saves space and cost) that can spin and cause a valve train failure.

I wonder how well this multi-air system keeps its adjustment over time? I see that the exhaust valves are reliable bucket and shims, but the cam follower and hydraulic actuator scheme on the intake valve seems a little more questionable. The actuators appear to be a place for leaks to happen and a cam follower will wear faster than bucket-and-shim.

Too bad there is no adjust-ability of the exhaust valve timing, since fiddling with exhaust valve timing can greatly increase engine braking (crack the valve during the compression stroke, or open the valve late during the exhaust stroke). These being how Jakebrake and exhaust brake work, respectively. As the engine gets designed to be more efficient and spin more freely some way to get more engine back pressure (or maybe just bigger brakes?) seems like it will be necessary.

Its good to hear that there is an oil cooler. I presume that this is a water to oil heat exchange from your description (also a good arrangement).

I presume that the transmission has an oil to air heat exchanger. Does anybody have enough experience to know if transmission overheating problems are an issue with this 8 speed transmission? Having once had an automatic transmission boil over, spew fluid onto a hot exhaust manifold, and catch the vehicle on fire, I'm a bit leary of automatic transmission heat build up.
The cam drive sprockets are keyed.

Multiair engines have been in production since 2009 (including Fiat 500's). I haven't heard of any frequent problems.

The transmission cooler is a fairly large air cooled radiator mounted in front of the AC condenser. Based on the illustrations in the Service Manual, it looks to be the same size for all models including the QV. If that's true it's probably more than sufficient for the 2.0L models.
 

·
Registered
Tipo 33 Stradale 1/18 scale
Joined
·
3,787 Posts
For the gearheads out there, here's some stuff from the Service Manual on the 2.0L models that might be of interest:

1) The turbo intercooler is liquid cooled using a separate low temperature cooling system with an electric pump, dedicated reservoir, and front mounted radiator.
.
how does this affect switching the engine off whilst its spinning
is that the whirring noise you can hear after shutdown ? electric cooling ?
 

·
Registered
Joined
·
160 Posts
Discussion Starter · #8 ·
how does this affect switching the engine off whilst its spinning
is that the whirring noise you can hear after shutdown ? electric cooling ?
I didn't find anything in the manual to verify post-shutdown cooling of the turbo. The low temperature cooling system is used to cool the turbo bearing housing in addition to the intercooler so it makes sense that the electric pump would run after engine shutdown to get rid of residual heat.
 
  • Like
Reactions: Papa Gallo

·
Registered
Joined
·
1,964 Posts
Balance shafts?
Are these the twin balance shafts rotating in opposite directions at twice the crankshaft's speed as used by Mitsubishi Motors (the current patent owners) on their 4cyl. engines?
 

·
Registered
Joined
·
160 Posts
Discussion Starter · #12 ·
Balance shafts?
Are these the twin balance shafts rotating in opposite directions at twice the crankshaft's speed as used by Mitsubishi Motors (the current patent owners) on their 4cyl. engines?
Based on the chain drive sprocket tooth count in the illustrations, it looks like the right hand balance shaft runs at twice crankshaft rpm. The left balance shaft speed is harder to calculate because it's driven off the back of the oil pump with some gearing. Looking at the gear diameters and assuming it must be a whole number, it's probably a 2X multiplier also.
 

·
Registered
Joined
·
1,964 Posts
I found this image on one of the other threads.

This is described as the "air intake manifold with integrated charge air cooler and the hot-side turbo duct".
Zoom in and you can read MADE IN CANADA.
 

·
Registered
2020 Alfa Romeo Giulia Sport Ti AWD
Joined
·
7,462 Posts

·
Registered
Joined
·
86 Posts
Hi,
Can we add 2 air to air inter-coolers in parallel before the turbo, to beet the turbo lag?

Thanks
Hari
 

·
Registered
Joined
·
86 Posts
I didn't find anything in the manual to verify post-shutdown cooling of the turbo. The low temperature cooling system is used to cool the turbo bearing housing in addition to the intercooler so it makes sense that the electric pump would run after engine shutdown to get rid of residual heat.
Even after you lock the car and leave, if the parts under the hood are hot, the cooling system continues to run till it comes to safe temperatures.
 

·
Registered
2018 Q4 with Fiamenghi Ti exhaust, Race Mod, and Tecnico wheels.
Joined
·
7,729 Posts
Hi,
Can we add 2 air to air inter-coolers in parallel before the turbo, to beet the turbo lag?

Thanks
Hari
How would that help with turbo lag?
Maybe Nitrous injection that is only active while the boost is low? Good luck getting it to work properly though...

Don't racing auto-crossers dump and ignite fuel in the exhaust manifold in order to spin up the turbo all of the time? I can't imagine that being road legal though.

I think most of the lag in this system is not caused by the turbo. Most of it is likely to meet smog, fuel economy, and/or safety rules.
 

·
Registered
Joined
·
1,964 Posts
Hi,
Can we add 2 air to air inter-coolers in parallel before the turbo, to beet the turbo lag?

Thanks
Hari
Hari,
I agree with lockem. Additional cooling of the intake charge will not decrease turbo lag.
My understanding of turbo engine tuning, is that (greater) cooling of the intake charge will allow greater boost pressure and increased power, not decreased lag.
To decrease turbo lag (having maximum power at any rpm and any "throttle" opening) the engine needs the turbo spinning at as close to maximum speed as possible. This is difficult at idle engine speed and low RPMs while driving. Turbo designers and engine tuners have tricks to (do their best to) minimize lag. Newer street tuned engines these days manage turbo lag much better than in the 70s-80s etc. One interesting method is an electrical driven turbo charger that can maintain the turbo RPMs even when the engine is spinning slowly and the exhaust gasses passing through the turbo are minimal.
 

·
Registered
Joined
·
55 Posts
How would that help with turbo lag?
Maybe Nitrous injection that is only active while the boost is low? Good luck getting it to work properly though...

Don't racing auto-crossers dump and ignite fuel in the exhaust manifold in order to spin up the turbo all of the time? I can't imagine that being road legal though.

I think most of the lag in this system is not caused by the turbo. Most of it is likely to meet smog, fuel economy, and/or safety rules.
What you're referring to is called anti-lag, and it was pioneered in rally competition. It's a very impressive and effective technology but is extremely abusive on components. It's been around since the 80s and Porsche just this past year implemented it on the 991.2 carrera to appease those that didn't like lag in their "non-TURBO" turbo 911. I imagine it will be awhile before this trickles down into more commonplace turbo cars, if it does at all.

Personally, turbo lag adds a bit of drama to a car. But I understand why it can be frustrating.
 
1 - 20 of 31 Posts
Top