ALFAGTV6.COM

[kevin]

Jim, great idea grafting the fwd plenum underside into the red plenum. It does look better and keeps the character of the car but jeez it's way extra work especially making intake . Great job!

[Jim K]

Not really too much work...all I did is cut the chrome pipes like shown in the pic and connect them to the plenum with straight Samco reducers (51/45mm). I chopped the Samcos so as to have ~10-15mm clearance between the hood and plenum. I do like the way it looks and it doesn't restrict access to the coils and valve covers. I'll post some decent pics when the car comes back from the exhaust shop.
The only additional work not evident in this early trial-fit pic, is that I ground the chrome base flanges at an angle to even out the centerlines a bit -but this is not strictly necessary.
Jim K.

[Zamani]

JK,

Will raised bell mouths in the plenum be of any benefit? I coud get some cheap aluminum bell mouths and epoxy them into the rwd plenum. I'll show the conversion pipes I have for 24V + rwd plenum tonight.

[Jim K]

In which plenum? The std rwd one has very small diameters anyway.
I didn't consider adding anything, as the grafted part has excellent radiusing from the factory. If you have a similar fwd plenum, stick a finger in the throats and see how good it is. Theory also says that you should have adequate clearance over the bellmouth...Not much room in there for the required distance.
Jim K.

[Greg Gordon]

If you used those runners on the 12 valver, could you still fit the fuel injectors? Or would further custom work on a fuel rail be required?

Greg

[Jim K]

You'd need the 164 12v manifolds for that, where the chromes are bolted on. They look very similar to the 24v items. I'm pretty sure they'd fit as later 164 injector rails are almost the same as the 24v.
You're not talking about the curvy barbed rails are you?
Jim K.

[gran turismo]

Jim,
There is some interesting info about the stock plenum here: http://www.alfabb.com/bb/forums/engine- ... ction.html
This indicates that with the stock plenum there is poor air distribution at high rpm (with a modded 12V).

It will be interesting to see how your modified plenum works out.

Jeff

[Jim K]

Thanks Jeff, I had followed that thread. One point of interest: I have never found plugs of different color in any of my 12v 3liters so far in road or after dyno/track use. Its one of the things I was looking for to quickly check for mixture variation. I don't know what experience other members have had with this. We assume here that injectors are cleaned, tested and that there's a strong spark in an engine with no significant compression variation among cylinders -all reading 220psi +/- 2psi.
Jim K.

[Zamani]

JK

220psi is high. My 10.5:1 engine only has 180 psi +/- 5psi between cylinders. I'm assuming cam lobe, lobe separation and timing influences static compression readings? It consumes 1 litre of oil every 7000Kms. A pretty healthy engine I would say.

[Jim K]

Those values were measured a few months ago after break-in with Catcams 1030321's at 110* LC's and 11.5:1 CR.
Jim K.

[Jim K]

Ok, done with all engine work. The thing works and sounds great and dyno/mapping is scheduled for Monday+Tuesday. It will go on the rollers with ~600km and I suppose that's enough. I'm only concerned with ring seating before the dyno, as bearing clearances are all proper for a trackday engine and don't require a lengthy break-in period.
Here are three views of the engine.
Jim K.

[la_strega_nera]

do want.

[Zamani]

looks nice, but the idle sounds a little lumpy

http://www.youtube.com/watch?v=QB5tZtO_ihE

This is 11+:1 and Clio V6 Cup cams (profile) ?

[Duk]

looks nice, but the idle sounds a little lumpy

http://www.youtube.com/watch?v=QB5tZtO_ihE

This is 11+:1 and Clio V6 Cup cams (profile) ?

That could be a result of the open inlet for the hot wire/film air flow meter. Apparently they can give out some inconsistent output if the air stream into them isn't nice and laminar (flow) across the sensing element. There may be turbulence as the air comes around the edge of the AFM housing inlet.

[Jim K]

Right, its better with everything bolted on but still a bit lumpy. The cams are Renault Williams 2liter production model profiles (8-10 years ago) and are sensibly different from stock Alfa 24v items. 4v engines will tolerate 1.1mm lift at overlap before going lumpy. Std 24v cams have 0.7mm and the Williams ~1.3mm...now you see? I don't know what cam timing the original Williams had, but I'd bet lobe centers were more than 110* before/after TDC.
Jim K.