Trying to learn more about 'head lift' as it relates to supercharged high performance V8s and best practice for prevention. I need to be better informed. Any personal experiences, links, would be appreciated. Thanks
Head Lift?
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High HP IC Engines, generate very high cylinder pressures.
On top of the above; these engines have a fast burn chamber.
When you ignite a fast burn chamber, at maybe only 20° BTDC, those
cylinder pressures rise very quickly, as the piston is beginning to move past TDC.
Cylinder heads then need to be 'clamped' to the engine block, in the best manner possible.
This is why the lsX Cylinder Heads have six head bolts, and not just four.
This is why members on this forum, informed you that you need to use the 'best' head studs.
Cheers
Thanks, I don't currently have the 'best' head stud option available, I now have a 'better' than stock option using ARP 8740 hex bolts. Doesn't appear the stock TTY bolts with the LSX six bolt pattern did as good a job as I was expecting. Hopefully the newer bolts will hold-up better.
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I was not aware you lost a head gasket, my friend?
NP... Turned-out to be the unlikely cause to my problem.
I've learned these engines can produce some serious power when running optimum fuel and tuning! I imagine eventually rings and bearings will be next on the list?
When I pulled both heads, I noted the lifted head TTY bolts felt like they were welded into the block, and threads were wet with oil and coolant upon removal.
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Good head fasterners
Good head and block surface
Multi layer head gaskets
Don't get too greedy with timing/boost
Doing this everyday I know where to stop, but someone learning and relying on a knock sensor to tell them when to stop may go too far.
I am going to tame it down a bit for sure this time around. I'm learning you can only push things too far until something gives. I'm just happy it was only a head gasket this time. Now that I have stronger head bolts installed, don't even want to imagine what could possibly be the next level of "least path of resistance!"
I previously posted an image of a piston I had cleaned the surface to inspect, this may be the image you are referring? However, the two separate attached valve images represent a comparison of the #8 valve compared to all the other valves with carbon buildup, #8 valve is too clean. The cleanliness of #8 is a partial reason I concluded that there was a small coolant leak, even for a relatively short time period. In addition, replacement head gasket 1-3-5-7 made no improvement.
Didn't you post "before" pix of 2-4-6-8 pistons?
I recall mention of #8 intake being clean(er)
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I think there’s some confusion…
If the head gasket was blown, even leaking just a small amount, he would have been losing water, and would have been required to replace that water from time to time.
I don’t recall him asking where the water was going…
I don’t recall reading anything about him replacing water in the radiator because of a leak.
What I recall, is him complaining about a smell, which was later linked to an open PCV system.
The OP needs to set up a build thread, and put his build into his signature line. Otherwise, he continues to start thread after thread, and nobody knows what his build is. This tends to lead to confusion…
If the head gasket was blown, even leaking just a small amount, he would have been losing water, and would have been required to replace that water from time to time.
I don’t recall him asking where the water was going…
I don’t recall reading anything about him replacing water in the radiator because of a leak.
What I recall, is him complaining about a smell, which was later linked to an open PCV system.
The OP needs to set up a build thread, and put his build into his signature line. Otherwise, he continues to start thread after thread, and nobody knows what his build is. This tends to lead to confusion…
I am trying something new on this point. I have turned my oppressively ponderous sig into a simple LINK. Hopefully it will cease creating reading difficulty for others.
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And you also have a comprehensive build thread, a single place where you write about your build, and where one can go to locate information regarding your build, which in turn reduces confusion.
I made mention that I though #8 may have a blown valve seal and attached an image of the cylinder wall with oil residual, but I believe that's it?
I was losing coolant, not an extreme amount, between the time I realized an issue existed to the time spent troubleshooting and repair, was not considerable. I began this particular thread specific to learning more about head lift and how to best prevent it, got some good feedback. I didn't plan to intermingle or elaborate information from my other post, that was not my intent. I was asked for information relating to my other post and was simply trying to provide it. The burnt rubber/oil odor was a subject from my other post, not intended for this one. Thanks
It was quite a bit of effort for me to isolate and evaluate the number of symptoms i was experiencing at the time and put together a methodical plan to move forward. Thankfully I was able to resolve all issues and correct the conditions that contributed to the failures.
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As one builds more HP into an engine, one will also increase the pressure in the cylinder.
***This is often given as the BMEP, or the average pressure in the cylinder, for which I have the formula in my signature line.
In order to avoid this happening, one must clamp the cylinder heads to the block, in a more efficient manner.
To accommodate this; larger and higher quality head studs are often used. Same thing with pushrods. When spring pressures are increased, one must also increase the strength, e.g. material / diameter / taper of the pushrod.
If you had lifted a head, you would have (more than likely) torched the head gasket, and possibly the head. Believe me, once the head has lifted, it does not take much time to torch either the head gasket, or the head. This is why I became surprised, as you had not, to my knowledge, brought up head gasket issues within your previous posts.
Finding a little water within the head bolt threads of the block, in my opinion, does not indicate that one has a blown head gasket. Water goes everywhere, when one removes a cylinder head. A compression test is usually performed before taking the heads off. After the cylinder head has been removed from the engine block, a simple visual inspection of the head gasket will show one if it is blown.
Cheers
Thank you for the response. I first removed the odd bank head because during cylinder boroscope inspection I thought I may have a burnt intake valve and made the decision to remove the head, no damage, reinstalled. I did have compression test information for both banks before head removals. Based on other troubleshooting actions that did not improve my issue, my last resort was to remove and replace the even bank head gasket due to a slight loss of coolant and no carbon buildup on #8 intake valve, call it a long shot. I mentioned that the bolts seemed welded into the even bank and were contaminated as compared to the odd bank in the case it might have some meaning? Afterwords the negative engine behavior was resolved. The compression results after re-installation were improved on the even bank, but nothing phenomenal.
One thing to watch out for: Make sure you blow out those head bolt holes (w bores covered). People have refastened their heads again and the hydraulic pressure from the hole with some coolant has cracked blocks. And as rubber duck said, when a head comes off it is pretty hard to avoid coolant going everywhere
Thank you, excellent point! Fortunately, I made sure to prepare the holes using an ARP tool, solvent, and high pressure air. And did in fact protect the engine from anything getting blown out that could migrate.
To think that such a small amount of trapped fluid in the wrong place could cause such a catastrophic event, hope to never experience that scenario!
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