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RB30 Head Gasket thickness for more boost

VL_Turbo
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Piggaz
Piggaz

What’s the limit of boost at 9.0:1? Very curious to know.

FiXtUrE
FiXtUrE

From my understanding you can achieve about 5 - 10 psi with 9:1 - 9:5:1 comp safely before it goes pop.. before you think this wack boost levels, you have to consider the turbo, dump back exhaust, fmi

FiXtUrE
FiXtUrE

Regardless to fuel it’s the boost/comp pressure that will determine if it gos pop or not.

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VL_Turbo Contributor

VL_Turbo

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16 minutes ago, GTSBoy said:

Only if the CHRA is completely cracked through. Which doesn't happen.

only way really to find out is if I Dona coolant pressure test, disconnect the oil drain and see if coolant leaks from there?  Or the other option head gasket? But very unlikely as I just replaced it which leave maybe piston bores have a hairline crack? I dunno lost for words now. 

VL_Turbo Contributor

VL_Turbo

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Posted (edited)

 Did a compression test and all cylinders were even. 
4 things come to mind.

1. Head gasket - which I just replaced, MLS 12mm with copper spray for extra seal. (Not losing coolant )

2. CHRA - leaking through turbo drain and into sump ( coolant pressure test will confirm this tomorrow )

 

3. cracked head ( been repaired and machined. ( didn't even reach operating temp before unnoticed coolant in oil pan)

 

4. block (piston bores cracked) 

more investigating 🤦🏽

Edited by VL_Turbo
VL_Turbo Contributor

VL_Turbo

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14 minutes ago, GTSBoy said:

No. That makes it more likely.

Thinking of maybe replacing the Nitto MLS gasket and replacing it with a Genuine Nissan head gasket. 
 

only went Nitto MLS due to it being a 1.2m thickness to reduce comp. 

Ben C34 Grand Master

Ben C34

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Posted

you never needed to reduce comp, but anyway.

 

How sure are you that the block surface was  all good ? It is a nightmare getting old gasket off. how did you do it?

copper spray isnt a normal thing to do. how much did you spray on? Have you done that before?

 

 

the chances of the turbo being the issue are so slim, but you may as well check.

VL_Turbo Contributor

VL_Turbo

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1 minute ago, Ben C34 said:

you never needed to reduce comp, but anyway.

 

How sure are you that the block surface was  all good ?
(used knife sharpening block)

 

It is a nightmare getting old gasket off. how did you do it?

( knife sharpening block and sand paper on a block with wd40 and brake cleaner)

copper spray isnt a normal thing to do. how much did you spray on? Have you done that before?

3 layers of copper spray, no, haven't done it before.

( wouldn't compression test eliminate all this, came up good all the cylinders were even?

 

1 minute ago, Ben C34 said:

 

 

the chances of the turbo being the issue are so slim, but you may as well check.

 

Duncan Grand Master

Duncan

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Posted

Can you take us back to the start? Why were you doing the head gasket in the first place?

It is possible to get simple things wrong in this job....

Did you check every hole in the supplied head gasket matched the block and head orifices?

What procedure did you follow to tighten down the head? Do you know your torque wrench is calibrated properly? Are the head bolts still tight now? 

Also I remember something about some blocks and needing to seal studs to the water jacket, not sure if that was rb30 though

VL_Turbo Contributor

VL_Turbo

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1 hour ago, Duncan said:

Can you take us back to the start? Why were you doing the head gasket in the first place?

It is possible to get simple things wrong in this job....

Did you check every hole in the supplied head gasket matched the block and head orifices?

What procedure did you follow to tighten down the head? Do you know your torque wrench is calibrated properly? Are the head bolts still tight now? 

Also I remember something about some blocks and needing to seal studs to the water jacket, not sure if that was rb30 though

Runt too much boost on a hot day with nearly 300,000ks on the motor. Old head gasket was worn out.

with the head bolts I followed the Gregory's manual. Used head stud and lube on the head studs.

 

will take rocker cover off and recheck the torque, I believe it was 97nm for head studs. 
 

no idea about what you mean to seal head studs to water jackets?

GTSBoy Grand Master

GTSBoy

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15 minutes ago, VL_Turbo said:

no idea about what you mean to seal head studs to water jackets?

Some head studs' drilled and tapped holes go through to the water jacket (On some motors. And Duncan was saying he didn't recall if RB30s were one of them, and I don't think they are).

On those motors you can't just screw them in, you have to apply thread sealant before you put them in to stop coolant coming up the bore of the stud hole and arriving in places where it is not supposed to be.

Duncan Grand Master

Duncan

Posted
Posted

We might be able to advise you better with more detail. When you say 

46 minutes ago, VL_Turbo said:

Runt too much boost on a hot day with nearly 300,000ks on the motor. Old head gasket was worn out.

What did you notice happened, and what have you done since? For example,

did the car run hot?

did oil/water mix in the engine, and if so how did you flush the block, oil cooler (if fitted), oil/water interchange (if fitted), radiator?

did you use new head bolts/studs?

did you get the head checked for straightness?

after you prepped the block surface with a sharpening block/wd40, how did you check it for straightness?

46 minutes ago, VL_Turbo said:

with the head bolts I followed the Gregory's manual. Used head stud and lube on the head studs.

will take rocker cover off and recheck the torque, I believe it was 97nm for head studs. 

- what was the procedure you followed, did you tighten then down in steps and was there an order to tighten the bolts from middle to outside?

VL_Turbo Contributor

VL_Turbo

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21 minutes ago, Duncan said:

We might be able to advise you better with more detail. When you say 

What did you notice happened, and what have you done since? For example,

did the car run hot?

Ran to half temperature, didn't get hot. Turned it off.

did oil/water mix in the engine, and if so how did you flush the block, oil cooler (if fitted), oil/water interchange (if fitted), radiator?

coolant and oil did mix, flushed the block via a bolt under the coolant line for the turb. No oil cooler fitted. But I did install a new trans cooler so avoided trans line connected to radiator. 

did you use new head bolts/studs?

Yes, new ARP head studs and bolts 11mm.

did you get the head checked for straightness?

yes, crack tested, pressure tested, new valve stem seals.

after you prepped the block surface with a sharpening block/wd40, how did you check it for straightness?

checked with a straight edge.

 

VL_Turbo Contributor

VL_Turbo

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Posted

Done compression test came up as follows

1- 111psi, 2- 115, 3-119, 4- 120, 5-120, 6- 115

 

done coolant pressure test and not leaking or losing coolant and definitely not losing coolant via turbo drain. Puzzled is understatement atm.😳

Duncan Grand Master

Duncan

Posted
Posted

The extra detail does help. What was it that made you check for a headgasket issue in the first place if it never got hot?

I'm thinking it might be fine and the milkshake is just from the original failure. Try changing the oil again and see if it is getting better or still bad.

The coolant pressure test is a good check but it can miss an issue which only occurs when hot or at much higher pressures (like compression pressure)

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VL_Turbo Contributor

VL_Turbo

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1 minute ago, Duncan said:

The extra detail does help. What was it that made you check for a headgasket issue in the first place if it never got hot?

alot of white smoke came out of exhaust.

I'm thinking it might be fine and the milkshake is just from the original failure. Try changing the oil again and see if it is getting better or still bad.

I'll get new oil now.

The coolant pressure test is a good check but it can miss an issue which only occurs when hot or at much higher pressures (like compression pressure)

I'll put new oil and leave it idling for 10-15 mins, will have to bed the new cam in as well. (Stage 2 Kelford 226F).

 

VL_Turbo Contributor

VL_Turbo

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2 hours ago, Duncan said:

absolutely, either a specific product or just throw some diesel in with the oil for 5 minutes.

I bought Penrite flush oil. Went online and I was told it can harm the engine?

this is my Nitto 1.2mm multi layer steel head gasket, can only go on one way right?

D646BA98-8CC8-4AF5-9B48-61A6D3FBFA8F.jpeg

Edited by VL_Turbo

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