RB26 Grout Fill

[Dorifudo]

Hi all,

Just wanting some advice regarding grout filling blocks.

Long story short, i am looking at building a new short block for my car as the current one has a 1mm crack that has been JB Welded and with the power it will eventually fail.

I have managed to find a virgin block r32 rb26 block, plan is to go billet main caps and plate. After talking to a few people online some people running big power on the cast blocks have also done grout fill along with bracing of some sort. I have talked to my engine builder about the idea of going half grout fill as it is still a street car and the setup for billet block is out of the question.

My engine builder has used Hardblok on old V8's, however they were for dedicated drag cars on methanol so heat is not really an issue. The issue is he has concerns about the grout separating from the bores from heat expansion with the different materials.

 

Cheers 

Jeff

[GTSBoy]

I think that the conservative approach is to grout up to the bottom of the lowest welch plug(s). Adds some stiffness but still allows the coolant pretty much full access to the bores. It doesn't put any grout around the part of the bore that might expand from internal pressure, but it certainly locates a clamp around the bore which constrains how far down the bore any such movement can occur, thereby reducing the amount of movement that can occur in the top half.

Perfect? No. Better than nothing? Of course.

There have been many people on here who have done pretty much what I described above. Read these.

https://www.sau.com.au/forums/topic/429446-strengthening-a-rb26-block/

https://www.sau.com.au/forums/topic/431462-grout-fill/

https://www.sau.com.au/forums/topic/210084-rb26-resin-filled-blocks/

 

[Shoota_77]

My experience counts for zero as my engine has done no more than idle in the shed but I've done the grout fill to the base of the welsh plugs.  The lower part of the engine is the most common (only??) place that the blocks crack so makes sense to me to do it.  The hottest part of the block (top 4 inches where combustion happens) is not affected by grout so I see zero issues there.  I really see no downsides to it so if it only made 10% improvement surely it's worth it for the minimal expense of doing it.  I look at this way.  If I cracked a block and HADN'T done the grout, I'd never forgive myself for not giving it a fighting chance!

[GTSBoy]

44 minutes ago, Shoota_77 said:

The lower part of the engine is the most common (only??) place that the blocks crack so makes sense to me to do it.

I think I've seen RB26 (in particular) failures up high on the exhaust side near #4.

[cachorro]

On 6/15/2021 at 4:01 AM, GTSBoy said:

I think I've seen RB26 (in particular) failures up high on the exhaust side near #4.

I'm sure the half-filled grout would help additionally strengthen to some degree. Especially with a PRP brace. Are blocks still cracking on that area with either or?

[GTSBoy]

2 hours ago, cachorro said:

Are blocks still cracking on that area with either or?

No idea. But I think most people (in the stupid power brigade - ie the drag and runway guys) have quit trying to make stupid power on 2.6 blocks.

[r32-25t]

26 blocks are common for cracking the deck, talking to Herman from prp said even full prepped all high power 26 blocks will crack eventually 

[jet_r31]

Mines grout filled to the welsch

They actually always split at the top of the bore making big power.. 

Which is why herman was experimenting  with trying to fill top half instead.. 

[cachorro]

20 hours ago, r32-25t said:

26 blocks are common for cracking the deck, talking to Herman from prp said even full prepped all high power 26 blocks will crack eventually 

What kind of cars are breaking 26 blocks? I was watching Herman's youtube videos from 2 years ago and he said a number of high power GTRs are running the brace and not cracking blocks. He did mention grout filling too. I'm sure times have changed..

[r32-25t]

He didn't say an exact number, just big power. Mine cracked the deck in 3 spots with 485kw at the wheels but that was only an unopened engine with head studs fitted 

[WantGTR]

Grout fill won't hurt. It's cheap anyway so do it.

If block cracks anyway what's the point of spending 2k+ on a brace?

If youre pushing 400+kW in a 'street car' it aint gonna be as reliable as social media say it's gonna be anyway. *flame suit on*

Thats the sport. Make bulk power and shit breaks.

[r32-25t]

He also said his cast block which fixes all the rb26 blocks issues should be out by the end of the year. I for one am keen to see it 

[GTSBoy]

2 minutes ago, WantGTR said:

If block cracks anyway what's the point of spending 2k+ on a brace?

There's almost certainly shades of grey here. For one thing, every engine and block is different. There's a bell curve of outright strength. On top of that, there's all the thousands of variables of how that block has been treated across its years of use, the power level that it has been run at, the particular mods/method by which the power is being made (ie power from more revs or power from more cylinder pressure). + how it is used. Street vs circuit vs drag, etc etc etc.

Then the next shade of grey is, for any given block, wherever it falls on that bell curve, surely adding the block brace still has benefits. Making the bottom end even less likely to walk around, for one. But I'd still expect it to raise the limit of that block before it will break. Trouble is, you can't go pulling out anecdotal evidence of "this block ran for 2 years at XXX HP without a brace and was fine" and "this other block broke at less HP with a block brace added", because the bell curve created by adding up all the uncertainties is likely to be far wider than the difference in power of those engines.

Unless you are in a position to gather a large number of statistics your (anyone's) statistics must be taken with a huge grain of salt. Confidence levels are only built up by having many examples with almost no difference between them to describe the average behaviour of that type of example (along with the other statistical parameters of interest, particularly the SD). There's no point comparing two examples if the stats are so poor that the SD is several times wider than the difference between the examples.

[WantGTR]

1 hour ago, GTSBoy said:

There's almost certainly shades of grey here. For one thing, every engine and block is different. There's a bell curve of outright strength. On top of that, there's all the thousands of variables of how that block has been treated across its years of use, the power level that it has been run at, the particular mods/method by which the power is being made (ie power from more revs or power from more cylinder pressure). + how it is used. Street vs circuit vs drag, etc etc etc.

Then the next shade of grey is, for any given block, wherever it falls on that bell curve, surely adding the block brace still has benefits. Making the bottom end even less likely to walk around, for one. But I'd still expect it to raise the limit of that block before it will break. Trouble is, you can't go pulling out anecdotal evidence of "this block ran for 2 years at XXX HP without a brace and was fine" and "this other block broke at less HP with a block brace added", because the bell curve created by adding up all the uncertainties is likely to be far wider than the difference in power of those engines.

Unless you are in a position to gather a large number of statistics your (anyone's) statistics must be taken with a huge grain of salt. Confidence levels are only built up by having many examples with almost no difference between them to describe the average behaviour of that type of example (along with the other statistical parameters of interest, particularly the SD). There's no point comparing two examples if the stats are so poor that the SD is several times wider than the difference between the examples.

i agree with what you are saying, lots of variables to take into account. i was just trying to make a point

 

People tend to jump on the bandwagon and want to include all the latest fancy new parts whether they are necessary or not. With today's technology, making 1000 or more isnt as out of reach as it used to be. Fact is there are more and more engines out there making lots of power even without braces. Toward the top end of the power spectrum, i firmly believe none of these engines are reliable no matter how well they are built or what parts are thrown into them and they are no where near as 'streetable' as the internet makes them out to be.

Either way you go, grout/no grout, brace/no brace, billet/cast, it is going to cost money and expect failures - not if but when.

 

Happy Modding.

[GTSBoy]

Yes.

[cachorro]

9 hours ago, WantGTR said:

i agree with what you are saying, lots of variables to take into account. i was just trying to make a point

 

People tend to jump on the bandwagon and want to include all the latest fancy new parts whether they are necessary or not. With today's technology, making 1000 or more isnt as out of reach as it used to be. Fact is there are more and more engines out there making lots of power even without braces. Toward the top end of the power spectrum, i firmly believe none of these engines are reliable no matter how well they are built or what parts are thrown into them and they are no where near as 'streetable' as the internet makes them out to be.

Either way you go, grout/no grout, brace/no brace, billet/cast, it is going to cost money and expect failures - not if but when.

 

Happy Modding.

I think a brace is pretty clear that it is actually a very worthy mod. Yes, we can argue that every mechanical part can break with enough heat and stress but your points are blinding the degree to which this is highly probable vs. not.

[Shoota_77]

10 hours ago, cachorro said:

I think a brace is pretty clear that it is actually a very worthy mod. Yes, we can argue that every mechanical part can break with enough heat and stress but your points are blinding the degree to which this is highly probable vs. not.

The grout is a no brainer, the brace is a bit different as the cost and effort involved is a lot higher once you factor in machining, etc.  At the end of the day it's like an insurance policy.  You hate paying for it and hope you don't need it but bloody thankful you did have it when you needed it!

[Old man 32 GTR]

I remember not that long ago this topic coming up on a GTR page on FB. Herman stated that a block brace is essential for any serious build. Then Anthony Maatouk chimed in and stated he has never used a block brace on a 26 block, however all his builds use an N1 block, claimed over 150 builds and not one block crack, tagged numerous customers to confirm, cars that have been running for years. 
Now he also stated he is not against the brace and uses them in all of his RB30 builds. Just his opinion is they are not required in an N1 block. Now this sparked a lot of back and fourth between Maatouk and Herman. Was all very interesting to hear both sides of the argument. Herman stating he has seen numerous N1 blocks crack and Maatouk stating it was likely other factors that caused that, (pointing towards bad tune). 
from a more personal point a mate of mine has a Maatouk’s built 2.7, running a 76/75 making 1000+ hp, been running for about 3 years now without issue. (Not braced). 

[cachorro]

On 6/18/2021 at 8:04 PM, Old man 32 GTR said:

I remember not that long ago this topic coming up on a GTR page on FB. Herman stated that a block brace is essential for any serious build. Then Anthony Maatouk chimed in and stated he has never used a block brace on a 26 block, however all his builds use an N1 block, claimed over 150 builds and not one block crack, tagged numerous customers to confirm, cars that have been running for years. 
Now he also stated he is not against the brace and uses them in all of his RB30 builds. Just his opinion is they are not required in an N1 block. Now this sparked a lot of back and fourth between Maatouk and Herman. Was all very interesting to hear both sides of the argument. Herman stating he has seen numerous N1 blocks crack and Maatouk stating it was likely other factors that caused that, (pointing towards bad tune). 
from a more personal point a mate of mine has a Maatouk’s built 2.7, running a 76/75 making 1000+ hp, been running for about 3 years now without issue. (Not braced). 

Herman's videos are on youtube on the Motive Video channel and they are worth the watch. I wonder on what grounds Maatouk claims a brace is not necessary. It could be true but as mentioned, where on the bell curve does each individual block sit. Also there could be dozens of combinations of variables. Do you have a link to the facebook post? Curious to read up on it.

 

[WantGTR]

8 hours ago, cachorro said:

Herman's videos are on youtube on the Motive Video channel and they are worth the watch. I wonder on what grounds Maatouk claims a brace is not necessary. It could be true but as mentioned, where on the bell curve does each individual block sit. Also there could be dozens of combinations of variables. Do you have a link to the facebook post? Curious to read up on it.

 

On the grounds that they have extensive experience and a solid track record of building the fastest RBs in the country. No other workshop comes close to having as many tough RBs as this place in the Australia or possibly the world. They certainly have credibility to make comments about the platform.

 

note: i am not a customer of theirs at all but just calling a spade a spade.