cablebandit

iTrader: (37)

Who has lifted the head on an iron block with normal runs...no detonation? I really wonder if the heads are to blame. Old school fords have our bolt configuration (i think) and dont have near as much head lifting issues as us. Yes the decks might be thicker on the heads but even the AFRs are lifting on the ls1 with a lot thicker deck. Why do we never crack heads when FI cars blow from detonation? I have cracked blocks every place they can be cracked but never a head. Just wondering outloud after reading MightyMouses HG post.

b1er

iTrader: (1)

It must be a

Jerry,
I think we're on to something.....I wish others would chime in with some ideas....

longrange4u

iTrader: (2)

I asked this question several times before my build.... There were a few that have done it on Alum blocks, Erik Koeing explained that to me as "Due the the flexibility of alum under heat and high rpm's it is more likely to flex under the head... even if only temporarly" Hope I quoted that close.

I havent found a case of someone lifting a head on an Iron block under 1400RWHP.... Can anyone tell us otherwise?

Julio

Could camshaft profile possibly contribute to this?

Coming from tuning on turbo Buick engines that are junk.. head gaskets 99% of the time let go do to detonation creating the spike in cylinder pressure.

Typically EGT's will rise to really high levels then the "torch" happens and a nice groove is burned through the head gasket/head/whatever. Seen plenty of race cars with torched aluminum heads.

I have also seen plenty of heads lift when flat tappet cams started going flat.. exhuast lobe starts to go.. cylinder pressure goes up.. pooof.


Just thinking out loud.. the Buicks have been boostin since the 80's..

Zombie

iTrader: (2)

[QUOTE=Julio]Coming from tuning on turbo Buick engines that are junk.. /QUOTE]

Finally someone admitting it LOL Turbo's really help to mask bad design... to a point

gametech

iTrader: (1)

Turbos are like crack or heroin, they cure everything until you run out of money.

distortion_69

iTrader: (20)

Just out of curiosity, anybody ever tried out the 6l iron heads from a few years ago? Wonder if materials on the actual cylinder head changes anything.

Peace,
Josh

cablebandit

iTrader: (37)

Why has nobody cracked a head? I have destroyed blocks with detonation but never a head...not even warped one...that doesnt make sense

TwnTrboCE

iTrader: (43)

We have. The problem is that the overly big water passages are so close to the bores. Add a bunch of cylinder pressure and you push water.
We have ran about every combo except iron heads(i'd rather push water) and have pushed water. We can run a combo for a long time with a lot of boost and little timing and hardly push any. Add timing and it starts pushing quite a bit. On a drag setup this has been no big deal at all. On a old set of gaskets and lots of timing we have pushed up to 1/2 gallon on a pass. That motor is still going strong today.
As far as cracked heads. The ones on my LS2 block have cracks between the seats in every chamber. Just had them checked and a valve job done. Very old set of heads and have been ran 1000+hp for a couple years.
I believe the heads on the LSx motors cool fairly well. Keeping them from warping and cracking.

nitrousboyWS6

iTrader: (19)

I lifted my heads and burnt a hole from the combustion chamber to the water jacket. 6.0 iron block with 317 casting heads. But what I don't understand is why the nuts on the head studs were lose. We could take them off with a 3/8 inch ratchet. But on the other side of the motor you needed a braker bar. Explain that one.

cablebandit

iTrader: (37)

could we weld up the passages a little smaller maybe?

kp

iTrader: (34)

TwnTrboCE is 100% correct.

Making the coolent holes smaller in the head would help some I would think, not sure why all the aftermarket castings use the stock design since the holes in the MLS gaskets are small. I'm pretty sure the ford guys use larger studs and they are closer together then the LS1 stuff. I'm sure they are not 100% problem free at high boost levels either..

TS6

iTrader: (41)

Yeah, the ford guys have the same (if not worse) problem. I had a turbo mustang for awhile, and did alot of research. The head bolt setup is very similar to an LS1, and has the same problem. Those guys go through head gaskets like crazy too. The other problem with the ford stuff (at least 302 stock block stuff) is the blocks don't take high HP very well, especially at high RPM's. I had to shift mine at like 5500 max, making 475 at the wheels on pump gas. The good side of it was the motor was STOCK, as in stock valve springs, heads, bottom end, etc. Just a turbo kit, fuel system, intake (it was laying around), and clutch. Fun car. Ran high 11's at 125+ MPH. I like my LS1 better.

Julio

That Solara that runs 6.50's runs 65+ PSI boost. The trick... perfect surfaces. The block and head are wet sanded in a criss cross pattern until all the surfacing marks disappear.. nothing special.. just proper prep. And they use those fancy studs used in top fuel.. a set for an engine can cost 3K. Think he said "tool steel" for the studs. The regualr studs will yield under high pressure.

I personally asked the head porter the question.. and they use an MLS gasket installed dry.

Tiago

iTrader: (27)

So far mine has not lifted on the street ... we'll see at the track