Which heads, etc., with the aluminium 3.0L block? 2.4L, 2.8L, 2.7L or RS4 ???
10-15-2006, 09:00 AM
#1
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Which heads, etc., with the aluminium 3.0L block? 2.4L, 2.8L, 2.7L or RS4 ???
<center><img src="http://gallery.rennlist.com/albums/album531/30lblk_rs4_int_28hds2.jpg"></center><p>
The photo was provided to me by a friend and shows the aluminium 3.0L block matched to 2.8L heads and RS4 intake. I have pretty much decided that I am going to go with the aluminium 3.0L block & crankshaft.
So on to the heads. What I am initially thinking is to start with the 2.8L heads and have them ported. Then put 1mm larger valves in to them with sodium filled exhaust valves. From searching the forum, it looks like there is a slight difference in the oiling system between the early and late 2.8L heads so I guess I will try to find a late 2.8L head.
To avoid additional stresses and because I don't think it is worth it on a turbocharged engine, I don't intend to make the engine rev any higher than about 7,500 RPM. My feeling is that the stresses on the bottom end of the engine go up considerably as you rev it. I think it makes a lot of sense with the aluminium block to keep the revs within reasonable numbers. One advantage of this is that I shouldn't need better valve springs or any changes to the valve train of that nature.
I am thinking I will use the stock cams.
Comments?
Especially, is there any advantage to starting with a different head than the 2.8L? If the heads are going to be flowed, then does it even make a difference? Any advantages to the RS4 heads? Or anything else?
Am I making a mistake not trying to rev the engine? And if I were to try to rev the engine to, say, 8,500, then what would I need to do to the valve train to make it last? How much extra power might I make?
Stephen<ul><li><a href="http://gallery.rennlist.com/gallery/album531">Audi 3.0L engine block</a></li></ul>
The photo was provided to me by a friend and shows the aluminium 3.0L block matched to 2.8L heads and RS4 intake. I have pretty much decided that I am going to go with the aluminium 3.0L block & crankshaft.
So on to the heads. What I am initially thinking is to start with the 2.8L heads and have them ported. Then put 1mm larger valves in to them with sodium filled exhaust valves. From searching the forum, it looks like there is a slight difference in the oiling system between the early and late 2.8L heads so I guess I will try to find a late 2.8L head.
To avoid additional stresses and because I don't think it is worth it on a turbocharged engine, I don't intend to make the engine rev any higher than about 7,500 RPM. My feeling is that the stresses on the bottom end of the engine go up considerably as you rev it. I think it makes a lot of sense with the aluminium block to keep the revs within reasonable numbers. One advantage of this is that I shouldn't need better valve springs or any changes to the valve train of that nature.
I am thinking I will use the stock cams.
Comments?
Especially, is there any advantage to starting with a different head than the 2.8L? If the heads are going to be flowed, then does it even make a difference? Any advantages to the RS4 heads? Or anything else?
Am I making a mistake not trying to rev the engine? And if I were to try to rev the engine to, say, 8,500, then what would I need to do to the valve train to make it last? How much extra power might I make?
Stephen<ul><li><a href="http://gallery.rennlist.com/gallery/album531">Audi 3.0L engine block</a></li></ul>
10-15-2006, 09:06 AM
#3
i actually prefer the early oiling system in the 2.8 heads. Also..
..if you go with larger valves, id do it on the exhaust side only. there really isnt much room on the intake side.
I believe 2.4, 2.8 and RS4 heads all have the same size intake ports (~55mm IIRC). Supposedly the RS4 heads have been optimized for max heat dissipation by cosworth, but im not sure how true that is.
I believe 2.4, 2.8 and RS4 heads all have the same size intake ports (~55mm IIRC). Supposedly the RS4 heads have been optimized for max heat dissipation by cosworth, but im not sure how true that is.
10-15-2006, 09:07 AM
#4
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I think that they are very similar.
But not identical.
One thing I've read is that there might be more cooling on the RS4 heads.
But I'm thinking that they are similar enough and if I am going to go with larger valves anyway, then I don't have to concern myself with what stock valves are already in there. Ergo, no need for the 2.7L or RS4 heads as a starting point.
Stephen
One thing I've read is that there might be more cooling on the RS4 heads.
But I'm thinking that they are similar enough and if I am going to go with larger valves anyway, then I don't have to concern myself with what stock valves are already in there. Ergo, no need for the 2.7L or RS4 heads as a starting point.
Stephen
10-15-2006, 09:11 AM
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Why do you prefer the earlier oiling system?
It was actually a comment of yours I saw in the forums that tipped me off to this difference.
Usually the desire is to increase the size on the intake side more than on the exhaust side. Plus there is less stress there because heat is lower. One advantage of not increasing the intake size is that I can then use stock intake valves.
Is there an advantage to 2.4L vs. 2.8L heads?
Stephen
Usually the desire is to increase the size on the intake side more than on the exhaust side. Plus there is less stress there because heat is lower. One advantage of not increasing the intake size is that I can then use stock intake valves.
Is there an advantage to 2.4L vs. 2.8L heads?
Stephen
10-15-2006, 09:13 AM
#7
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I doubt it would cost me that much to find a couple of RS4 heads if I were already in Europe.
But if there isn't a difference then what's the point?
I'm actually wondering if 2.7L heads will do just as well if they are going to be ported anyway.
Stephen
I'm actually wondering if 2.7L heads will do just as well if they are going to be ported anyway.
Stephen
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10-15-2006, 09:16 AM
#8
the "integrated oil supply" seems more geared towards ease of manufacturing than providing optimal
<center><img src="http://pictureposter.audiworld.com/26545/cambearingoil.jpg"></center><p>oil flow. I worry that it could be part of the problem some have seen with abnormal cam and cam bearing wear. Probably a groundless suspicion, but the traditional oil galleries seem a little more 'tried and tested' to me.
10-15-2006, 09:17 AM
#10
oh, and from what ive been told re: oversized intake valves, with the three intake valves so close
togehter, there's really no way to hog out the ports leading to them enough to take much advantage of the larger valves. one idea may be to enlarge the center port only and use a +1mm valve there.