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Discussion Starter #1
Hopefully everyone is doing well!

I'm setting up this page as I am hoping someone has any other ideas of what my issues could be.

Let me give you guys the low down on the situation at hand.

Car: 2011 Sti Sedan
Engine: Element Tuning Pro Comp "race" block
Specs: closed deck ej257 case halves(billet inserts), element tuning forged h beam rods, Manely forged pistons 99.75, arp ca625+ 11mm headstuds(95ftlbs sequenced), 2017 sti nitrided crank new with forged bearings. Bc280 cams with ferea valvetrain and over sized valves. Cometic head gaskets with beautiful RA finish of the heads and block.

Cooling: Koyorad with 1.5 bar cap and 1.3 bar cap on expansion. Oem fans and shroud. Ets 3.5" core front mount intercooler

Boost: ets rotated kit with elh and a gen 2 GTX3576R 4inch inlet and tial 44mm mvr. GrimmSpeed EBCS.

Fueling: IAG v2 fuel rails on ID2000's, cobb flex fuel kit and radium twin pump hanger. Hardwired both with secondary being on a 12psi set hobbs switch. AN lines front to back. Aeromotive FPR set at 43.5 psi base pressure

Engine management: Cobb AP v3 flex-tuned for e75%. 500whp/445wtq @24.5psi

Now before we get into it i recently had to tear this thing apart and redo the head studs because i believe they originally came with arp2000s and they lifted and i started pushing coolant. Now it is on ca625+ studs and thicker cometic head gaskets. The heads have been touched up to flatten it out and checked for cracks as well.

Aside from another leakdown test and tear down to magnaflux the block, I have done all I could think of. It shows similar symptoms to a head gasket issue. Cold start has bubbles in the expansion tank, pressurized coolant hoses, excess coolant in the overflow. Filling overflow bottle under boost. The coolant doesnt completely return to the radiator after cooling(my main evidence to support the theory).

Things I have done are compression test(passed) Radiator/cooling system pressure test(holds just under cap release pressure for 5-10 min.
Boost leak test(passed at 24psi).

What I think is wrong:
I'm starting to get to the point where I think there may be some sort of crack or breach in the block opening up and slowly getting worse. The cometic install and arp ca625+ stud job came out beautiful and was brought up to 95 ftlbs of torque.
The problem that arose for me was overheating randomly on just daily driving and never above wastegate spring. I would let it cool off until the morning and pop the cap on the expansion tank to see it slightly down(about half inch) and the top section of the radiator was also low. So I look at the overflow and it was full to the cap. I fill it and bleed with a spill free funnel. Let it go through 5-6 fan cycles and cap it. Later in the week it happens again. The next morning i put the spill free funnel o the upper expansion tank and cold start it. Sure as it was there were small bubbles(simmering sized almost) floating up through the funnel. Whats weird is when i rev it up to see if it bleeds anymore is that more coolant gets sucked into the block when i do instead of it just gurgling from a spinning water pump.

Never have i had this issue before with any IAG blocks built or an outfront.

What are your thoughts? Im saving up for some case halves from IAG as we speak and just driving the car offboost and monitoring it.

Gonna swap over my internals to the new IAG case halves when we find a problem after magnafluxing this element tuning block.


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I was just going back in my own build thread reminiscing (lol) and saw all your posts from when you got the 35r on there. So I looked at your post history, and saw this unanswered.

What do your plugs look like?

I had a block (non subaru) develop a pin hole at the verrrrry top of the cylinder. It filled the cylinder with about a liter of coolant lol.
 

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worked on a few Toyota trucks that we kept doing headgaskets on...as we noticed repeat customers we reached out to Toyota as the machine shop saw 0 issues with the heads or blocks and comment was microscopic pinholes in head due to manufacturing defects where we received new heads and had no further returns for that issue...

also why not run a higher pressure radiator/expansion tank cap?

also with these metal headgaskets was advised to add copper gasket spray thoroughly before install...
 

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Discussion Starter #4
I was just going back in my own build thread reminiscing (lol) and saw all your posts from when you got the 35r on there. So I looked at your post history, and saw this unanswered.

What do your plugs look like?

I had a block (non subaru) develop a pin hole at the verrrrry top of the cylinder. It filled the cylinder with about a liter of coolant lol.
So my plugs are actually pretty solid. The gap opened up a tiny bit.( 2 thou ) but i closed them back up.

So now the coolant is the weird part of of this whole situation. All the coolant is accounted for. Its gets pushed out into the over flow mainly because the pocket of air is heating up, expanding, creating pressure and opening the expansion tank cap and going to the overflow. But if i were to say let it cool, open the expansion tank cap, take whats in the overflow and fill the system again im at the same exact level as where i originally filled and bled it.

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Discussion Starter #5
worked on a few Toyota trucks that we kept doing headgaskets on...as we noticed repeat customers we reached out to Toyota as the machine shop saw 0 issues with the heads or blocks and comment was microscopic pinholes in head due to manufacturing defects where we received new heads and had no further returns for that issue...

also why not run a higher pressure radiator/expansion tank cap?

also with these metal headgaskets was advised to add copper gasket spray thoroughly before install...
We copper sprayed it, ran a 1.3 bar cap on the expansion and a 1.5 bar cap on the radiator. But there is definitely something going on that could potentially involve the block. I wish i had a gas content analyzer to see what type of gas is getting into the coolant system so it would point me in the right direction.

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So my plugs are actually pretty solid. The gap opened up a tiny bit.( 2 thou ) but i closed them back up.

So now the coolant is the weird part of of this whole situation. All the coolant is accounted for. Its gets pushed out into the over flow mainly because the pocket of air is heating up, expanding, creating pressure and opening the expansion tank cap and going to the overflow. But if i were to say let it cool, open the expansion tank cap, take whats in the overflow and fill the system again im at the same exact level as where i originally filled and bled it.

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This isn't just the a bad or improper radiator cap not allowing the coolant to return?

Have to ask.
 

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Discussion Starter #7
This isn't just the a bad or improper radiator cap not allowing the coolant to return?



Have to ask.
Correct. I've used multiple brand new oem caps for both expansion tank and radiator. To be exact i have used 4 pairs. Then i went with higher pressure ones to make sure my assumptions of pressurization was correct.

After cooldown over night it SOMETIMES may pull a minimal amount of coolant back into the system. Only once have i seen it draw all of what was pushed out back in. Til this day i can not duplicate it.

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I think quite a number of owners have reversed the caps from top and bottom tank and had similar issues. Head gaskets not sealing is an issue sometimes too. 2L heads often crack, and though I've never head of them loosing coolant from it, I'm sure it is possible. Never heard of this in a 2.5l engine.
 

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Discussion Starter #9
I think quite a number of owners have reversed the caps from top and bottom tank and had similar issues. Head gaskets not sealing is an issue sometimes too. 2L heads often crack, and though I've never head of them loosing coolant from it, I'm sure it is possible. Never heard of this in a 2.5l engine.
I've never mistaken a cap on these things. The expansion tank with the higher position has the lower pressure (1.1 bar) cap on it. The radiator hasthe 1.3 bar cap on it.

The long block itself is less than 10k miles old and are brand new subaru oem case halves inserted with billet closed deck inserts with brand new 2018 heads.

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if you think you are still getting gas into your cooling system after pressure test, why havent you tested the system for gas content?
 

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Discussion Starter #11
if you think you are still getting gas into your cooling system after pressure test, why havent you tested the system for gas content?
It may not necessarily be combustion gas is what i am saying. By analyzing it and seeing exactly what make up of fumes is in the system it would point me to the part of the system that has that gas type in it. For example like Crankcase fumes or combustion or just oxygen in the case of a cracked head or skmething of the sorts.

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It may not necessarily be combustion gas is what i am saying. By analyzing it and seeing exactly what make up of fumes is in the system it would point me to the part of the system that has that gas type in it. For example like Crankcase fumes or combustion or just oxygen in the case of a cracked head or skmething of the sorts.

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Well, if the metal expands to reveal a small crack you cant really test the coolant system while hot unless you hooked up the air compressor to the expansion tank nipple thing. I'm not sure if it would push up on the cap to allow pressure in the system though.
 

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IF your coolant has not been changed, I suggest using a fluid tester for exhaust residue from pushing water. There are readily available kits to check for traces of petro in coolant.

Have the heads and block decks been checked for trueness (straight, flat and even)?
 

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Might be something as bizarre as a radiator hose that has a pinhole leak or not sealing at a clamp, but only during suction and not leaking under pressure.
If it is in fact overheating why not look for what's causing that? Radiator or thermostat?
 

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Discussion Starter #15
Update:

After a long draught process, the conclusion is that on ethanol and high boost, the car has been indeed lifting the center headstuds and lifting the heads.

My advice to anyone going into the 500whp-550whp territory to skip the gimmick of ca625+ stock sized studs and go to 13mm or 14mm studs.

I won't go into slamming the advice of certain companies and shops but after a grueling process and dealing with inexperience, talking to many time attack teams, drag teams, from around the us, uk, and aus. It is indeed lifting heads due to the onset of torque from high boost on a gen 2 35r with 280 grind cams and revving it to 7800rpms. The tune itself was a mid ranged tune designed to sustain power with low timing and higher boost. But cyl pressures were still enough to lift the center headstuds.

Forego the fancy materials and get the biggest headstuds you can during your initial builds. What a bunch of bologna i was fed in order to have money stolen from me.

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What was the process for determining that the center head studs were stretching? I mean, that's what I'm assuming you are saying; that the threads did not pull out in the case.
Did I miss your saying what the boost was that caused this? What gasket or sealing method did you use?
 

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Discussion Starter #18
What was the process for determining that the center head studs were stretching? I mean, that's what I'm assuming you are saying; that the threads did not pull out in the case.
Did I miss your saying what the boost was that caused this? What gasket or sealing method did you use?
We took before and after measurements of everything. Before and after of stud lengths, play in the threads, torque specs and just about everything you can think of and compared them.

Originally they had lifted under 28.5-29psi of boost on e75 at 7500rpm. After the second rebuild with stronger studs of the same size we tried to dim the tune down ALOT and still had the same issue at less timing at 23.5psi. Both rebuilds were with the use of cometic MLS head gaskets and beautiful machine finishes to cometics specs. Heat and scorch marks that bypassed the gaskets and combustion chamber had showed each time but in a different spot. Both different cylinders and corners of where the chamber meets the heads.

But regardless of everything and everyone's weird take on the matter. It is absolutely a headlifting under high cylinder pressures with boost.

I would like to explain in more detail with the analytics and data but im too pissed off at some of these shops and companies that hire people who know squat about building a race car.


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What kind of controls were there on the build? Did you do it/oversee it or was it all farmed out? Was the CR ever verified in any way on either build?
Left out is your compression ratio or any other factor that could increase the effective CR. Do you know positively what it is?
Did both instances of lifting occur while it was on the dyno and were you able to data log to verify that there was no detonation or pre-ignition and that air/fuel ratios were correct? Did any experts evaluate the heads, spark plugs or pistons for pre-ignition? Was everything else fine on teardown? Fuel quality verified?
I ask because 23.5 PSI shouldn't lift a head with real ARP CA625+ studs unless your CR or some other factor were out of whack.
I have a similar setup with 24 PSI and 8.5+ CR (stock gasket with once shaved heads). No other magic potions to the build other than the studs. I run Kelford 272's on this ported, 1mm+ valves, DAVCS engine.
Besides hours on the dyno, I have fifty track hours on this darlin' and it's been to 8K many times with most shifts at 7.5K.
For what it's worth, I have heard rumors of bogus ARP bolt products. Send some to ARP to be tested?
 

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Discussion Starter #20
What kind of controls were there on the build? Did you do it/oversee it or was it all farmed out? Was the CR ever verified in any way on either build?
Left out is your compression ratio or any other factor that could increase the effective CR. Do you know positively what it is?
Did both instances of lifting occur while it was on the dyno and were you able to data log to verify that there was no detonation or pre-ignition and that air/fuel ratios were correct? Did any experts evaluate the heads, spark plugs or pistons for pre-ignition? Was everything else fine on teardown? Fuel quality verified?
I ask because 23.5 PSI shouldn't lift a head with real ARP CA625+ studs unless your CR or some other factor were out of whack.
I have a similar setup with 24 PSI and 8.5+ CR (stock gasket with once shaved heads). No other magic potions to the build other than the studs. I run Kelford 272's on this ported, 1mm+ valves, DAVCS engine.
Besides hours on the dyno, I have fifty track hours on this darlin' and it's been to 8K many times with most shifts at 7.5K.
For what it's worth, I have heard rumors of bogus ARP bolt products. Send some to ARP to be tested?
I oversaw all of it during both rebuilds. Everything was done in reputable shops for both machining and tuning. The rebuilds itself was done under my own hands. After building a few dozen 2jz and ej amd k24 and d16s i am pretty confident.
Comp ratio was actually on the lower side due to the slightly thicker headgaskets but more or less within the stock range. The first time it lifted was on a live log on track. No det, no pre, just pushing coolant at a steady rate after a certain boost number. Fuel quality was verified. Everything is in immaculate shape as the motor and internals have less than 10k miles on them.

24.5 psi on a 35r can definitely lift stock sized head studs. It has done so in many cases around the world. Maybe you are a lucky one?

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