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Ultimate 6.2/6.5 engine build questions

Ratman said:
I'm sure I'll take a beating for saying this, -but most steel stud girdles are a waste of time.

Steel is soft and elastic, -cast iron, -not so much. By the time the steel has any opportunity to take any load, the cast iron is already broke.

In order for the piece to truly do any good, it needs to be made of a similar material to the block that has the same modulus of elasticity.

Most stud girdles merely slow the parts down as they are coming out.

Ok, bash away.....
Click to expand...

LOL-> you asked for it!

I will agree that the recycled bedframe method of tying the main caps together is probably feeble but how do you explain the use of billet steel main caps on racing engines? There is as much of a difference in material on that application as ours.
 
Ratman said:
I'm sure I'll take a beating for saying this, -but most steel stud girdles are a waste of time.

Steel is soft and elastic, -cast iron, -not so much. By the time the steel has any opportunity to take any load, the cast iron is already broke.

In order for the piece to truly do any good, it needs to be made of a similar material to the block that has the same modulus of elasticity.

Most stud girdles merely slow the parts down as they are coming out.

Ok, bash away.....
Click to expand...
you took the words right outa my piehole
 
Jasonsmack said:
LOL-> you asked for it!

I will agree that the recycled bedframe method of tying the main caps together is probably feeble but how do you explain the use of billet steel main caps on racing engines? There is as much of a difference in material on that application as ours.
Click to expand...

Well, there's a big difference. The billet caps are ROBUST in comparison to most of the poor excuses we see for stud girdles. The billet caps work just fine. The real deal here is YIELD strength, -and the billet steel caps are well up to the task of providing that.

Now, like GJF stated, on the gasser stuff, harmonics play a much bigger role in bottom-end failures than pure stress and fatigue (as is the case with our stuff). Bolting extra malleable metal to the bottom doesn't really strengthen it, it changes its resonant frequency so that it doesn't self-destruct (much like the rubber-band lead weights used on a brake lathe are used to prevent squealing and chatter when turning rotors).

So, with that said, there really isn't much we can bolt onto the bottom of our junk that's going to save it.

Studs are GOOD. Lock and stitch is PROVEN. It is also a known fact that heat plays a role in cracks, -no matter WHICH block you have, -be it a 599, 929, 506, etc, overheating will eventually kill it. Splayed mains are a great idea, -even better if you have a block like bison's that does not have the outer holes drilled (metal left in the webs is GOOD). The latest and greatest concept of running a cemented block has also proven to work well for short-term high-stress situations (as is the case with the Heath salt-truck).
 
Ratman said:
Studs are GOOD. Lock and stitch is PROVEN. It is also a known fact that heat plays a role in cracks, -no matter WHICH block you have, -be it a 599, 929, 506, etc, overheating will eventually kill it. Splayed mains are a great idea, -even better if you have a block like bison's that does not have the outer holes drilled (metal left in the webs is GOOD). The latest and greatest concept of running a cemented block has also proven to work well for short-term high-stress situations (as is the case with the Heath salt-truck).
Click to expand...

Hmm, I really am interested here too. I want to beef up the bottom end as much as possible. So you are saying splayed mains are probably the best idea?
 
FWIW my (2) "at risk" 98 squirters have done quite well 156 K on one, & 176K on the other one; is one block better than another, possibly, but if you'll look at depth of cut for piston bores and remaining web material, you'll see come are cut deeper than others, I think that may be a componet to the fail mode.

That said I think most significant contributor to those that have failed probably belonged to somebody else before the 6.5 mafia guys/crew you see on the forums took possession of them some 3x owenrs in the lot; and probably more than once were worked in overheat H2O/EGT scenario, or weak boost and POs did not know this is a bad thing, we "enlightened" owners know better, had GM made some of the improvements we have made with advent of the forums and us sharing notes, I think the 6.5 would have had a better reputation than it wound up with.

I built my project engine with splays, was gonna go 18:1 to reduce stresses when I fitted a Holset et al, high boost turbo onto it, ATT negated that issue, I went with 21:1 per Heath recommendation, and now feel that splays were overkill, especially since I have a Scat crank and fluid damper on it.

Mentoned before is Heath method fill em with concrete and run em, good enough for 153 mph, and many sustained daily driving/towing miles, can't argue with results IMO.
 
Turbine Doc, Do you regret not going 18:1? If you had to do it all over again would you stay 21:1 ?

I am thinking hypothetically, that a 18:1 motor would have less block stress since the cylinder pressures would be less off load which the motor is seeing most of the time anyways.

Next question on concrete filled blocks.... How do you contend with a block heater and concrete fill?

To be honest if one would actually build a REAL girdle that would tie the oil pan rails in and combine a windage tray into the same unit IMHO think it would be just as strong as splaying the caps. This method would add triagulation to the main caps and tie all the main studs together and take care of harmonics at the same time if there are any.
 
GJF said:
Next question on concrete filled blocks.... How do you contend with a block heater and concrete fill?

To be honest if one would actually build a REAL girdle that would tie the oil pan rails in and combine a windage tray into the same unit IMHO think it would be just as strong as splaying the caps. This method would add triagulation to the main caps and tie all the main studs together and take care of harmonics at the same time if there are any.
Click to expand...

Most blocks are filled to just below the frost plugs, so the block heater is normal operation. I think any more than that and you run the risk of greatly decreasing the cooling ability of the motor.

There have been several guys who have custom build a full girdle that connected all 5 mains instead just the middle three like the kits offer.
I will try to find a picture.
 
Why worry about which block to get? If you're going to be spending anywhere near $7000, just call Peninsular and buy yourself a P400 and be done with the worries.

Of course, you'll need to make your own oil pan, but that's a small price to pay.
 
Here is that girdle I spoke of:
P1010025-r.JPG

This one is made out of 1018 cold rolled steel
The major disadvantage to this is that the oil pan will need to be modified.
 
well.................. I fabricate, and I just like to do it. I like to make things better and make it look just as good as it works. It is just something I do. It is what makes me, me. Plus what fun would it be to just buy something you have no idea what the clearences are? You could hope the assembler had a good day and not a bad day. I'm not trying to degrade anyone, and in no way am I suggesting Penninsular doesn't know what they are doing. I just like to know what is what. Plus with the economy the way it is it is easier to do steps instead of forking out 7K. BTW this is my other toy hand built completely by me.
 

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I have a main girdle on mine made of 1" x 2" keystock. I would have to call the guy that sold me the material to tell you what grade it is, I can not remember. Mine fits fine without oil pan modifications but I have about twenty hours into them.
 
Thanks Matt!

This is definetly better than the bed frame rail girdle. :laugh:

I know it would be more work. I would deck the main caps and add material across the cap and bridge both rails. Then tie into the pan rails. A custom pan would need to be made. Maybe a extra capacity pan.
 
Ratman said:
Well, there's a big difference. The billet caps are ROBUST in comparison to most of the poor excuses we see for stud girdles. The billet caps work just fine. The real deal here is YIELD strength, -and the billet steel caps are well up to the task of providing that.

So, with that said, there really isn't much we can bolt onto the bottom of our junk that's going to save it.
Click to expand...

So you are saying the time and money myself and some others have spent building main girdles are a waste of time?
 
Seems to me all the main stream guys making big power with the 6.2/6.5 are twisting the motor up to or over 5K.
It is these forums that help all the owners gather info and take the bull by the horns to make bigger strides in more power. If you think about it these are the only trucks that don't really have readily availible performance parts. The parts that are used are just later model pieces or parts from the next generation vehicles. Not bad for a 20 year old + engine.
 
Jasonsmack said:
So you are saying the time and money myself and some others have spent building main girdles are a waste of time?
Click to expand...

I think what Rat was referring to were the plethora of flatbar girdles out there from various vendors sold as THE cure for what ails the 6.5, that aren't a cure.

Waste of time, no but as in my case with my splays I think probably overkill, but if you got the skills and time to build something more substantial than raw or powder-coated flatbar it ain't gonna hurt.

I doubt I'd be buying such a thing for the average engine, now one hopped up taking on lots of boost, or supercharged, I mite have a go at it, but Heath's approach seems a lot easier, and works for ones they sell.
 
Actually if you go back and read what he said he initially went on a rant about girdles. Then on a rant about how the metalurgy does not match between cast iron and steel. Then indicated what he said does not apply to race engines because they are different.

I do agree that the angle iron girdles are probably not worth the money and I do know that I will never bother to put one on my engines but, I have built enough race and diesel engines of wide varieties to know that he is steering people in the wrong direction with his statements. In the same post he praises one method yet says there is nothing we can do to save our junk. Really?? I might be stuborn, but I have yet to figure out why some people have to be so negative when solutions like this are being discussed. It is discouraging to the new guys.
 
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