Raceboy

Lol I am not talking about valves, I am talking about head and block If valve is burnt due to non sealing or bad heat transfer (usually result of bad tune), then combustion during valve being open breaks the boundary layer and that will overheat the head.

Nothing to do with normal operation.

Duke

In the 8v more energy (heat) is lost through the exhaust, I would not consider that a benefit.
You have to admit that you are a bit all over the place. You start with saying that 90% of all 16v turbo engines have failed which is completely unfounded and now we have moved on to diesel engines. I don't think it's very serious and will stop posting in the thread (time better spent elsewhere ). Again, I have nothing against the 8v and I'm sure your engine will be a blast. But the 16v head has been proven to work very, very, well for a turbo engine. That's my last 2 cents

Thom

I am not sure I understand the point you are trying to make by posting a picture from a head that is not from a S/S2/968... Could it be that you generalize so much that you believe the issues that may rise on other platforms will necessarily occur with a 16V 944 turbo engine, while such issues have clearly not been recorded (ok, so far)?

You may as well dismiss the 2V head because it vaguely looks like an early GM head from the mid 50s... unless you want an indestructible tractor engine making a whopping 80hp, of course.

For your record, I never had a problem with the 4V heads on the turbocharged BMW S62 (on stock internals) that I tuned, and it made 500hp and 730N.m all day long, for what it's worth.

Voith

The problem here and the reason for existence of this thread is this:

It is not true and every thread I open even the 8v 535whp thread, there is all that repeated over and over.

It is simply utter BS. Hands down 4v flows better and has modern combustion chamber shape.

But, it comes with twice as much moving parts with extra chain and tensioner known to fail and is structurally not as strong as 8V head plus it features valves meant for natural aspirated cars.

So there is ~10% more top end for 4V VS more reliability for 2V.


When choosing between the two, these are the options, it is not superior by all acounts. Sorry.

Voith

Why do I detect this drama all the time? 90% is a guess based on the fact that I dont see any 16V long timers around here with engines that didn't catastrophically fail at least few times.

I am not disputing 16V as being the best option for certain needs, but it is just not superior all around and it has its pitfalls and everybody that ever saw head rebuilt business up close knows this.

Thom

"It's not true" la la la.

I will leave you with your sandcastles. You have so little clue what you're talking about it's been actually funny, but it looks like I have run out of coins to put in the BS jukebox. Have a nice day

Voith

Superior by all acounts.

JET951

We have built a few 3.0ltr 16v turbo engines now and while i would consider them on the cheaper side of the 3.0ltr build. Reason i say this is that for all of them that we have done the only changes internally have been con rods and pistons. In our case Wossner rods and pistons. All other moving parts have been factory. In the case of the head it gets new chain and tensioner pads. Standard cams, valves and springs. From this we have had great longevity with the 3.0ltr block and 16v setup. Our own car has over 75,000kms on it a 1.5bar boost running E85. Driven everyday and also competes in our state supersprint/motokhana season.
At the end first year we pulled the pan to insect the big ends, which happened to be as good as when they went in. On the boost we run we have now seen double the amount of track days per cometic head gasket as we were using on the 2.5 8v setup. Blow by is almost non existent compared with the 2.5 block and 8v head. Im not sure exactly why but the 8v setup does throw a lot more oil through the catch can system. Lastly the 16v setup has a larger power band gavin similarly sized turbos for both 2.5 and 3.0ltr. On the 2.5 we would reach 1 bar by 3200rpm and it would seize to make power past 5600rpm even with the 9r camshaft. On the 16v engine we see 1 bar at 3000rpm and continue to make power through to 6500rpm.
With all of these positives its hard to go past a 16v setup if you can afford them, And on that end they really do not cost much more then a 8v build. Just get yourself a S2 or 968 donor engine.
Regards
Sean

333pg333

May we presume that you are essentially stating that by definition of the extra valves all multi valve (read, more than 1 in and 1 ex) are inferior to 2v heads in a structural and thermal sense? Then I must be safe in assuming that all modern car manufacturers are wrong in building all their multivalve turbo charged motors and there is clear evidence of this because of the millions of cracked heads around the planet?


btw...where are all these failed 16v Porsche turbo builds anyway? I can't think of many/any at all. I need my aging memory to be jogged. :-)

Voith

Yes all 4V heads are theoretically structural inferior to 2V heads, thermal picture depends on many factors thermal conductivity and size of valves is for instance one of them.

More holes means less material and less material tends to break sooner.

Basing a engineering 'superior by all acounts' claim on few 16V cars that work versus 30 years and 100.000+ example proven reliable setup is stupid.

Where are the 9 16vT cars from 3.0 list? Havent seen them lately.

Its like half of the super duper 'superior by all counts' solutions that float around like wet sleeves, balance shaft deletes, all sorts of pistons, cranks and whatnot solutions, then there are people pulling engines 5 times in a row because wet sleeves are superior yet there are million kilometer original alusil cars that just work.

Btw: try to find an audi RS4 with a head that is not or was at one point cracked.

refresh951

Voith - Is logic not allowed? I am at a loss to understand your position. Sure, many 3L motors have failed but you have to look at why they failed. I cannot think of a single 3L failure caused by the head. The failure possibilities are endless, bad tunes, #2 rod, cracked block, rings, pistons, rod failure but head failure does not really enter the list. If you have not noticed we have been trying to address these issues (dry sump, hybrid strokers, etc) and some real progress has been made. There is no real practical evidence to support your position.

alxdgr8

And this is exactly why I hardly post on Rennlist anymore... Back to working on my car instead of talking about it.

refresh951

I do not mind these kinds of discussions. Sometimes it prompts some knowledgeable people to contribute and then everyone benefits. The reason for this thread makes no sense but there is some great info here none the less.

333pg333

So wet sleeves etc are mutually exclusive to 16v motors? Plenty more 8v failures due to similar issues. I take your point as far as dealing with potential issues once customising begins but that isn't what is in question. If we concentrate on your point that 16v motors are not as good as 8v due to cracked heads, there would be very few example of these that I can recollect. Quite possibly this is due to the owner or builder not wanting this to be known? I have read where Chris White and Michael Mount have heard or had cracked 16v heads but I believe this was on the first version from the 2.5ltr motor. The S2 was stronger and the 968 stronger again. Essentially if the motors can be made to last without cracking the heads then yes, they will be superior in every way. Until there is overwhelming evidence showing a multitude of cracked heads then I think we can feel safe enough that following this path isn't necessarily bound to fail that you might have us believe?

Voith

There are only few examples of built 16 valve turbo cars. That is experimental at best, not a proven reliable solution.

Multivalve heads crack on multivalve turbo cars that were tested to oblivion, and they still crack and here I am expected to just buy the package since few people had good results and everybody else is all wet about the idea?

Failures on piston engines are sometimes simple but other times they are result many undetected factors.