Twins with Twins, Anyone?

kidturbo

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How much Boost you push through these motors???
Well that's where things get really strange, and this block question comes in to play..
Ya have 2 identical engines, both running same RPM and HP most of the time. Both tuned identically. With boost in the 30-40 range, no issues on either Above 40psi, one engine starts leaking into cooling, while other engine is fine.

Running the Evans coolant, the Happy engine has less than 3psi on the system at any time no matter how hard ya push it. However on the dyno we noticed some coolant pressure creep on the Stbd or Problem Child engine soon as we got into the mid 40's psi or above 800hp range. You can actually see it on a gauge we had hanging in those videos.. Soon as we pushed 50+Psi and 900hp, it popped the cap. We wrote that off to those early LML head gaskets.

Now 3yrs, 4 Victor head gaskets, and 2 different heads later, problem childs leak pops up again, soon as I cranked up the power into that 850-950hp range. Just like it did on dyno. Other engine has literally ate a billet turbo wheel, and then drank couple gallons of salt water next day out, and still only make 3psi on the coolant system.. It's a beast.. lol

So if this was a single engine setup, one could speculate a bunch.. However, when ya have 2 with identical hours, and only one has this issue... Believe this project has taught us, if one fails, second is not far behind. Except for this issue.. My money is on the deck surface. :)
 
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1FastBrick

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Well that's where things get really strange, and this block question comes in to play..
Ya have 2 identical engines, both running same RPM and HP most of the time. Both tuned identically. With boost in the 30-40 range, no issues on either Above 40psi, one engine starts leaking into cooling, while other engine is fine.

Running the Evans coolant, the Happy engine has less than 3psi on the system at any time no matter how hard ya push it. However on the dyno we noticed some coolant pressure creep on the Stbd or Problem Child engine soon as we got into the mid 40's psi or above 800hp range. You can actually see it on a gauge we had hanging in those videos.. Soon as we pushed 50+Psi and 900hp, it popped the cap. We wrote that off to those early LML head gaskets that we on there..

Now 3yrs, 4 Victor head gaskets, and 2 different heads later, problem childs leak pops up again, soon as I cranked up the power into that 850-950hp range. Just like it did on dyno. Other engine has literally ate a billet turbo wheel, and then drank couple gallons of salt water next day out, and still only make 3psi on the coolant system.. It's a beast.. lol

So if this was a single engine setup, one could speculate a bunch.. However, when ya have 2 with identical hours, and one only one has this issue... Believe this project has taught us, if one fails, second is not far behind. Except for this issue.. My money is on the deck surface. :)
As I was reading this, I was thinking Deck surface, Then I got to the end and your conclusion... :LOL:

Where they ever decked to begin with????
 

kidturbo

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Well..... I purchased these LML blocks from DHD and Tony's guy did the bore and deck. I requested they be decked .010 and they arrived stamped .005. When I called to ask, was told they didn't need 10. To which I replied, I'll tell Fingers to add 5 back to the piston tops then..
 

kidturbo

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My only question from day one has really been using C gaskets. My Dmax tech buddy has always preferred C, and that' what we went with. However, with the extra .005 on the deck, or extra .005 off the pistons, they will clear A's without issue..

Doesn't explain why one engine is fine and other is pissing coolant out every orifice. 50 pages back we talked about O-rings. Which I am all about going forward. But still wanta know why one is happy without and other is not.
 

1FastBrick

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Well..... I purchased these LML blocks from DHD and Tony's guy did the bore and deck. I requested they be decked .010 and they arrived stamped .005. When I called to ask, was told they didn't need 10. To which I replied, I'll tell Fingers to add 5 back to the piston tops then..
Need a Homer Smack My Head Emoji for these instances....

So were these New Or used blocks?
 
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1FastBrick

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My only question from day one has really been using C gaskets. My Dmax tech buddy has always preferred C, and that' what we went with. However, with the extra .005 on the deck, or extra .005 off the pistons, they will clear A's without issue..

Doesn't explain why one engine is fine and other is pissing coolant out every orifice. 50 pages back we talked about O-rings. Which I am all about going forward. But still wanta know why one is happy without and other is not.
With out checking the deck surface, it's hard to say. I wonder if there is a low spot there?

On the LS blocks it very common.
 

kidturbo

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Need a Homer Smack My Head Emoji for these instances....

So were these New Or used blocks?
Used, ultra low millage. Didn't need any bore work, but I wanted them both fresh with that .001 over bore for high revs and high heat. I believe a while back we also discussed the extra 0.0015 they somehow grew, that we only found after the dyno tear down. Not saying anything, nope, zip it...

One block had been hit pretty hard, pan was bent up. But block looked good to the naked eye.. I don't recall which block was which that was. I really hope it's cracked, but no Blue Devil goo sticking out anywhere. And that stuff is like Franks Red Hot Sauces, that chits on everything.. lol
 

1FastBrick

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Used, ultra low millage. Didn't need any bore work, but I wanted them both fresh with that .001 over bore for high revs and high heat. I believe a while back we also discussed the extra 0.0015 they somehow grew, that we only found after the dyno tear down. Not saying anything, nope, zip it...

One block had been hit pretty hard, pan was bent up. But block looked good to the naked eye.. I don't recall which block was which that was. I really hope it's cracked, but no Blue Devil goo sticking out anywhere. And that stuff is like Franks Red Hot Sauces, that chits on everything.. lol
Ok, I wasn't sure if they were New Blocks Or used with some heat cycles.
 

kidturbo

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Ok, I wasn't sure if they were New Blocks Or used with some heat cycles.
Yeah that was part of the reason I wanted new Used.

What's funny, when we first installed them in the boat, and got a few hours on em, that engine started leaking pressure in the upper 30's low 40's Psi range. We swapped heads, and it made no pressure on coolant with gauge making around 42psi. Thought it was a poor plane job, or possible crack on the heads. Then probably 60-70hrs later, it comes back in the,, mid 40's sustained.

Now when it acted up at LOTO, I purposelessly pushed them to the limit on that last run just to be certain we could find the point of failure. Cap sounded like a tea kettle when I shut it down. At least it gave some witness marks where she was leaking.
 
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kidturbo

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Nice example. And as he stated, no reported issues with engine before the tear down.

I'm thinking the science will show us that the combo of couple thou low in that area, and the thicker C gaskets, equals all good for first few cycles. Then the old head gasket starts to warble a bit. Both head and block show same leak patterns. So our gasses were going over and under equally for sure

On a somewhat related side note, the Jet boat engine that split a M-race piston, and I flew out and spent a couple days tuning on.. Week later it starts running like crap. White smoke, lower power, and finally blowing coolant. Upon inspection, the engine builder out there who put it back together, didn't get the head studs torqued right and she blew Both side gaskets..

I spent a whole day on that boat running the Snake river, it as fine.. 4-5hrs later, they took nuts off the studs with with bare hands. Go figure.
 

1FastBrick

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In his part 2, you can see the shadows left behind as he machines it until he gets it flat.

I forgot that guy also had a Dart SHP Race block with deck issues.

Source: https://www.youtube.com/watch?v=YAV9pd1OYKk&ab_channel=ParagonEngines


I would be real curious to see how the decks on the 2 blocks check out. Especially the one with issues.

I am curious if that other boat stretched the studs Or if there was another issue?

I know ARP changed there washers on the LS kits to a waved stamp on the bottom side so they would stay put and not slip when torquing the nuts on the studs.

In the past they also recomended pre stretching the fasteners by putting them threw a few complete Torque cycles. It also helped burnish the threads on the fasteners. Something they have also changed as they changed there lubricant.

The new LS kits with the wave washers take an additional 10Lbs of force in the final torque sequence.

I know they offer the Custom Aged 625 studs but at that point, I wonder if going to a larger stud would be more beneficial?
 

kidturbo

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Kinda why I was wondering if anyone had noted actual stretching on the Dmax studs. Both sets were ordered at same time. And this set, been torqued 3 times now. But as noted, few of them felt like maybe 60-70lbs when broke em loose.

Anyone here ever re-torque after running? I've seen where some say run them all down to 125, the back off and do again. I was ask by a couple people if I re-torqued them when it started leaking. Personally it seemed like a waste of time then. Looking back, would been curious to seen those #'s now.
 

1FastBrick

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Kinda why I was wondering if anyone had noted actual stretching on the Dmax studs. Both sets were ordered at same time. And this set, been torqued 3 times now. But as noted, few of them felt like maybe 60-70lbs when broke em loose.

Anyone here ever re-torque after running? I've seen where some say run them all down to 125, the back off and do again. I was ask by a couple people if I re-torqued them when it started leaking. Personally it seemed like a waste of time then. Looking back, would been curious to seen those #'s now.
In My opinion once they leak, Thats kind of too late. But I guess you would at least know if the nuts backed off.

On my stuff, I like to go back after a few good heat cycles before I even send it. But I don't have any D-max specific engine building experience.

I know on the LS stuff they go to a larger stud to increase the clamp load. But they also don't have as many bolts to start with either which is why the after market blocks utilize a 6 bolt design.
 

Fingers

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One of the Joys of aluminum heads is if you get them HOT, they will deform under the head studs. Then when they cool, the studs are loose. Solution comes from doing several things.
  • Find out why the head is getting hot.
  • Increase the clamping surface area for the stud. (bigger washers)
  • Ensure you are getting proper squish on your gaskets. At some point you have to move from torque based tightening to bolt stretch.
  • If you are going to run it hard, you have to go back and check the torque on the head studs once in a while. It never hurts to lay a wrench on them once in a while.
 

MarkBroviak

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This is why I told you that we run o-ringed block with 625+studs in anything over 700hp anymore because cylinder pressure makes them leak and you are in a situation where there is a completely different type of load on the motor that any truck will ever see. It sucks to see you have all the trouble but when you are done with it the project will be worth it I think! Keep it up brother, you got this!!!
 

kidturbo

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Thanks for the valued advice guys. And hindsight is 20 20 on the o-rings.. I bet they'd be good to 900ish with studs alone. Both run fine all day at 750hp. Tends to say I may have been over confident in that 900#... And while I hate to do it this way, if I have to yank that crank, this block or it's replacement is getting ringed. Other one is running way to good to screw with right now...

Fingers first point does raise a good question. For conjecture, lets say the same side of block has been our problem since day one. We know it's not a bad head, changed that. And If I'm remembering correctly, is typically same the side with majority of gasket failure issues over all engine models? GM actually put a flow restricting ring in the passenger side of rear cover with the LML introduction. WHY ?? Obviously they saw something to show majority of coolant flow was going to passenger side, so they restricted it. I on other hand, went a step above GM, and welded in a cover divider plate, and then routed each bank separately and directly off the electric circ pump.

Typing that, made me remember that the major difference between these two engines,, coolant pump position, and hose routing to the block. Both circulation pumps and heat exchangers are set inbound to the keel of boat, for clearance and weight. And hose routing is little more twisted on this engine. Enough that I took couple pics of a potential issues to address on the back of block. However, the biggest issue spotted, is actually to the side that "didn't" blow the gasket. See below.

Has anyone real world tested reversing the coolant flow? I recall a salt flats racer maybe did some related testing years back? It's been on my mind for a while, cause I'd like to relocate the thermostats and upgrade the coolant tanks while things are out. Running that Evans coolant, boiling on hot spots, shouldn't be an issue that could screw with change in flow direction. Boiling in the heads is what I recall as known coolant issues on other long term high power runners..

20221120_154703.jpg

20221120_154535.jpg
 
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Fingers

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You can cut the o-rings in the heads. Just a 5 mil bump makes a hell of a difference.

You can check the coolant flow balance, left and right, by measuring flow on the outlet side of each head. Don't even need to run the engine, just the pump.

Cooling balance inside the head is a bit more complicated...
 

gmc502

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how's the spray pattern of the injectors on the offending cylinders.espaecially the stream thats squirts to the thin section of the bore betw. cylinders.if it gets to hot on the thin area it will get to hot and fail there,
use to see this on our drag car,600 shot of nos fine,700 and above,,kaboom.