383LQ4SS

iTrader: (33)

All discussion is assuming you have NO detonation or preignition issues and assembly was correct.

Whats your opinion on the reasons why many have had water pushing around 1000 crank hp.

Anyone experianced this? what rwtq tq where you at. what did you do to help the situation and what was your result.

What do you guys think the reason for the head lifting is? I mean mechanically....what part or piece physically moves to comprimise the gasket seal? This question is what I am really interested in.

I have my own opionions...and as a result I have my own philosophy on certain parts. But I want to start a discussion on what opinions and practices everyone else has come up with?

Lets hear some input...

purdueranger

iTrader: (11)

my input would have to be cylinder pressure and elastic deformation of the head bolts/studs.

the bolts are in tension because the head is trying to lift up and the threads are holding it down, the metal can only take so much of a load before it starts to stretch and that is when the head gasket loses it seal. Now that is taking into consideration that the gasket isn't warn from too much milage.

I am just an engineering technologist who deals with high cylinder pressures at work.

383LQ4SS

iTrader: (33)

Excellent reply..
Ok...so you would suggest upgrading to something like the L19 head studs or machining for the largest stud possible?

Any guesss on increased HP level for stock bolts regular ARP studs L19 studs?

Any other factors?

purdueranger

iTrader: (11)

going from a 7/16ths to a 1/2" bolt/stud will help out a good amount.

One thing I like to do is get break away torques on all bolts on the head. this will tell you which one have stretched/lossed up compared to the others. You can only do this with a digital or dial torque wrench.

"mark the bolt and the loosen it up and then tighten it back up to where it was originally and then record the force it took to put it back into place."

Robert56

iTrader: (2)

I agree, the cylinder pressures are stretching the studs, and that's simply because there are not enough of them. Cure, L19's were my choice, and the added 40% clamping force over conventional ARP studs seem to be the ticket outside changing to a LSX block with more studs. I haven't seen the limit of my motor by any means, just getting started, but i suspect before I am done we will see north of 800rwtq. i don't want to say my goal is 1000rwhp, because i don't know if i have the sack to push it that far, currently anyway. though blowing up my 408 would in fact give reason to go biggest cube LSX, lol. What some builder have told me, is the l19s will do an equal or better job than the ½ studs, and in the long run are cheaper, though upgrading from standard to L19's is a small wad of $$. We also must consider a good head gasket, and most like the GM MLS, with some using copper spray, however, I did not on my MLS.

Now lets hear some of what your insight has garnered, as I know you have hit some pretty big numbers. You have a secret build going don't you?
Robert

Robert56

iTrader: (2)

At what time do you do this, in the beginning initially? Seems to be a pretty smart way to keep track of things if we can do it occasionally?
Robert

purdueranger

iTrader: (11)

You would have to do it during tear down. What you can do is use a paint pen that can withstand the heats of oil and mark your bolts/studs and periodically check them. I do this at work with diesel engines and the components that are on the engine. I had a problem with some bolts backing out and just marking them and watching them everyday we could see when they backed out. Now you can watch the fasteners that are exposed easier than the ones under the valve cover but it is quick and easy to remove it and inspect it.

1 more thing I would like to add, I always use my snap-on torque wrench when putting together my motor. I have it recalibrated every 6 months at work. this will insure that you are putting the correct load on a bolt and not be off. I have seen what happens when you don't torque down the bolts enough.

jmill96Z

iTrader: (3)

We use those torque stripes on aircraft too. Pretty handy for a quick visual inspection.

Beaflag VonRathburg

iTrader: (176)

I looked into doing both a little time ago for my set up. Head gaskets are my main concern and I want it to be reliable. In doing my research I found that it's actually about the same initial price for both. Now if you stepped up and used 1/2 inch or 5/8 L19 studs you'd really be clamping the heads down.

One potential problem that comes with installing larger head studs though is that you are lessening the material that the studs have to hold them in place. The deck of the block is only so strong and removing material from the area that receives the most stress can be problematic if not performed correctly. The problem with the L19 studs is the hydrogen embittlement. I live a block away from the beach. With all the salt air I was concerned about long gevity of my head studs and preventing corrosion.

I was a little weary about having my local machinist attempting to install larger head studs and I didn't want to have to pay to ship out an iron block so that nullified that possibility rather quickly. The hydrogen embrittlement concerned me so I got rid of the L19 option as well. I thought I was screwed so I called up ARP. Upon talking to the special machine shop at ARP my questions were answered. (If you ever call ARP ask for the special machine shop number. The people who work at the main office have no idea what they are talking about and just read off information given to them.) Instead of utilizing L19 studs I'll instead be using their 625 material. The material has a greater tensile strength than L19 and isn't affected by hydrogen embrittlement. They are extremely pricey, but for what I'm looking for they'll work. I haven't ordered them yet, but I plan on doing so once I get working on my Formula again.

Here's a good list of materials, their average strengths, and usages:

XLR8N

iTrader: (3)

For everyone that is pushing water, where does it usually come from? Is it a certain cylinder? Does it come from the same place every time? Are you noticing any deformaties in the head gasket? Does the coolant get sucked in to the cylinders on the power stroke, or is it physically leaking from in between the head and block? The aluminum heads are a softer material than the head studs, is there a possibility that the heads themselves are maybe flexing?

383LQ4SS

iTrader: (33)

Keep em coming guys..we have barely scratched the surface here

383LQ4SS

iTrader: (33)

are you taking about "run on torque"? Basically the amount of force required to spin the bolt most of the threads engaged...but not tightened?

That is important when using bolts..and one great reason to use studs.

I have seen that a poorly cleaned block can have 5-10 ft/lbs of run on tq from the threads engaging before ANY clamp force is applied to the head. In that case...like you say...you need to find out your "run on" tq...and add that to the total tq. You need to do that for every hole. There can be as much as 10 ft/lbs difference from hole to hole.

Of course if you clean the block threads VERY well...run on tq should be VERY low and not be much of an issue. But things dont always turn out that perfect. So knowing that tidbit can help.

I always recomend studs to eliminate this issue completely.

Now....on the larger bolts. Why do the larger bolts help? Is it because the larger diameter bolt has larger cross section and resulting increase in stretch resistance? or could it be because the larger diameter hole also decreases the distance of the deck and head bolt holes. In other words...and 6 inch piece of wire hanger is bent rather easily...a 2 inch piece of wire hanger is much harder to bend.

Is the bolt stretching? or the head warping in the area between bolts? Is the aluminum deck between the bolts weaker than the bolts themsleves?

Typically the surface area of the hardware with a larger diameter bolt is also a larger diameter...the hardware is steel and "backs up" the aluminum. So even such things as larger diameter steel washers IMO can help....if it can be fitted.

IMO its a combo of increased resistance to bolt stretch with either L19 and/or large diameter bolts/washers reducing potential "flex distance" of the cylinder head deck.


What about deck thickness?

What about cylinder head material?

What about Tq management (since tq is a direct measure of cylinder pressure)?

daniel6718

iTrader: (36)

i dont think its the bolts as much as the head deforming with them stretching...reason why is most peopl switch tp thicker deck heads to help this problem...if what yall are sayin about bolts is true then the thicker deck wouldent help at all...the bolts would still stretch...so it has to be in the heads..not sayin the bolts arent adding to it though

383LQ4SS

iTrader: (33)

Good points!

02Z28

iTrader: (11)

Do you remember how much a set of the 625 head studs costs? Do you have to order them directly from ARP?

azceta

iTrader: (1)

I looked into different bolt/stud comparisons and have decided that if and when I build a motor expecting to reach around 1000 hp then it will probably be built off of the C5R block due to the existence of the larger 1/2 bolt holes and more head bolts to hold it down. That and how many other people are running that setup. Yes its not gonna be cheap but it would be worth it.IMO

ATVracr

iTrader: (5)

Me or Shiz have yet to have a head gasket issue.

No 1/2 head studs he ran L19's and I have ARP 2000 studs.

Cometic gaskets.

383LQ4SS

iTrader: (33)

How much power do you think your making at 149mph? Not sure if you dynoed...but best guess?

BTW...I have never had a head gasket issue either...atleast when i was sure that detaonation was not present.

ATVracr

iTrader: (5)

How much power does it take to to go 149mph @ 3725 lbs. ??

Shiz's car has been 156mph @ 3300lbs.


Edit.... http://www.dragtimes.com/horsepower-...power+Estimate

982 hp is what it says for mine.

383LQ4SS

iTrader: (33)

So right around 1000 crank HP and Shiz maybe a bit higher. Good info.

And neither of you have had water pushing and you have nothing special in the way of head gaskets or studs...just standard stuff?