V6 Strong modification

[slyalfa]

Quote:

Originally Posted by FMG_V6_btb that makes me think that maybe the continuous heating and cooling of the head is little by little pushing the external liners to the external side of the engine, Paco.

[FMG_V6_btb]

These pictures belong to a modified 3.7 engine which uses a sealing ring between the liner and the head (as pictured).

The sketch try to explain what happens during the thermal cycles.

The last picture show a possible solution (the engine in the picture is not an Alfa), but I think other solutions can be found.

In my opinion, to avoid problems, cylinder head must slide free on the block-liners when dilatation happens. In the case of this 3.7 engine, the ribs in sealing ring make move the top of the liner when the head expand, and this also produces deformation in the liner and misalignment of the piston-rod with the crank (not perpendicular), and this could produce irregular rod bearing wear. Are you agree with this? Has anybody seen Alfa V6 engines with symptoms of that?

Thanks Slyalfa, I will post some pictures with the needed dimensions to design a bottom end reinforcement as Marcelo pointed.

Thanks, Paco.

[FMG_V6_btb]

Sorry, I forget one picture!

[giuliettaevo]

Why not something like they use at autocomponenti?

[FMG_V6_btb]

Yes, that's good, also expensive, but maybe not necessary. On the other hand I'm not sure if this could be done in a big bore V6, for space reasons.

The problem is that in the Alfa engine the liner is supported near its bottom part, and in other engines, like the Ferrari 575 Maranello (which have aluminium+nickasil liners) the liner is supported and centered by its top part, this way it is not necessary to leave extra material to the liner over the block deck to compensate the different thermal expansion of the materials, because the expansion is absorbed by the sliding of the bottom part of the liner inside its crank housing… (I suppose is clear).

Paco.

[giuliettaevo]

How about milling off 1 cm of the top of the engine, so the liners protrude 1 cm extra above the engine. Now you can make a 1cm thick panel which has cutouts for the liners and waterjackets/oilgalleries. This panel will now keep the liners at the right place and angle.

Imagine just the top of the monosleeve from autocomponenti...

[Greg Gordon]

You could drop in an all aluminum small block Chevy for a lot less money. It would make more power, be lighter and have fewer moving parts. There won't be much Alfa left on a 450hp GTV6 or Milano no matter how you do it.

Greg

[FMG_V6_btb]

Thanks greg for your recommendation, but this engine will be fitted in a mid-engined sport car, and the gearbox will be Audi.

It is not only power what 'm looking for, are emissions too, the car must be homologated to run almost across Europe, and IMO the 2 valve small block can't afford the needed emissions level (its design is old compared to actual engines) maybe neither the Alfa, but I will try to modernize it as much as possible.

Remco, yes, that is what I though, but with some variations: The aluminium plate must be internal to the block sides but tightened by the head bolts, and the most important, the liner held in position by the aluminium plate. What is your opinion?

One thing, to reduce emissions during cold start (80% of the emissions on the European driving cicle EUIV are produced in the two or three first minutes, during the warm-up) the components around the combustion chamber must have as less thermal inertia as possible, that means better aluminium that Iron and thin walls in the liner.

Paco.

[Gabor K.]

Something like this for the road? This one is without turbo and around 450Hp.

[slyalfa]

there is a trick that newer cars use that they have a big bag that they pump the exhaust in to on startup then after the cat has heated they pump it back slowly thru the cat or mabee the motor?

also alfa added a oil warmer/cooler on the latter 12V and I am guessing on the 24V too
it lookes like a oil cooler adapter that goes in between the oil filter and the block. and you run the coolent thru it. it runs in the bypass path so it heats up the oil on start, also helps motor life as cold thick 20-50W oil does not flow much. and after the motor it at temp it helps cool the oil to the motor coolent temp

[giuliettaevo]

how about a CNC machined alu monoliner with Nicasil coating?

[FMG_V6_btb]

Pedazo carro!!! That 156 is super!, but no, my plan is for a "street car" the 156 is a racing car.

Slyalfa, the device you mention is a HC trap, implementation of this device is out of the scope of this project, just the engine management strategies for this function are very complicated

Here are some pictures from the Ferrari 575 liners and block. The liners are made from Aluminium and have nickasil coating, the block uses the closed deck concept design, and the liner is held by its upper part.

Paco.

[FMG_V6_btb]

Compare the Ferrari design with a Lambo (diablo) design.

The Lambo design is more similar to the Alfa than the Ferrari.

Remco, I think the best solution is a internal reinforced top plate with holes for the coolant flow, and with the Al-nickasil liners fixed in it. I will make a 3D drawing (but need some measurements).

Paco.

[giuliettaevo]

Measurements from the block? i have an open 2.5 laying around which i an measure up easily... nothing in it since it is my dummy-engine for fitting purposes.

[giuliettaevo]

Does the Ferrari use headbolts? I don't think it's closed deck, it has water jackets...