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Grout filling blocks - enquiry

Started by _Agent 34_ , Jul 20 2016 07:09 PM

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15 replies to this topic

#1 _Agent 34_

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Posted 20 July 2016 - 07:09 PM

I'm at the stage of over the next weeks on this race engine. The question of grout has come up and I held some talk this afternoon. there is only two options - to grout or not.

I spoke to the engine builder at length on this and he has not split a block, but he has been using longer rods in all his motors. 25yrs racing apendix j (15) and NC torana (10) - he also just builds engines.

BUT he has never grout filled a block either

I just wanted to hear any other input in this area from more experienced people than me or any other thoughts on this.

At this stage today we have decided not to grout fill based on reduced water capacity - but we have agreed that our USABLE target RPM is 72000 and also we have gone for a bit more torque through the rev range. it may rev harder but we are entering the limits of heads from this rev range onwards.

thanks in advanced

G

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#2 Redslur

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Posted 20 July 2016 - 07:48 PM

6 or 8?

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#3 _Bettle_

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Posted 20 July 2016 - 07:55 PM

I know it certainly stiffens up the base of the 308/304 blocks

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#4 mick_in_oz

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Posted 20 July 2016 - 08:18 PM

I've heard of some Holden 6's turning 12K rpm in some old speedway engines, but 72K!!!!!!! seems a little optimistic...

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#5 ozyozyozy

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Posted 20 July 2016 - 08:44 PM

Hahaha, maybe a 0 too many, thats HUUUUUUUGGGGGGEEEEE.

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#6 RallyRed

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Posted 20 July 2016 - 09:46 PM

what's Old Johnno's book say re this Grant?

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#7 S pack

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Posted 20 July 2016 - 09:53 PM

A previous thread about grout filling the Holden 6.

http://www.gmh-toran...-filled-blocks/

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#8 _oldjohnno_

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Posted 20 July 2016 - 09:55 PM

Think about this: if your rods and pistons weighed nothing you really could rev it to 72k and not stress a thing. To me the number one priority is to use the lightest pistons, pins and rods you can afford. The forces that break blocks are in direct proportion to the mass of the reciprocating bits and the square of the rpms.

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#9 _Bomber Watson_

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Posted 20 July 2016 - 10:13 PM

Think about this: if your rods and pistons weighed nothing you really could rev it to 72k and not stress a thing.

Valve springs might have a hard time?

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#10 _oldjohnno_

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Posted 20 July 2016 - 10:38 PM

Valve springs might have a hard time?

Duh everyone knows you have to put a couple of washers under them if you're gonna go over 65,000

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#11 Ice

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Posted 20 July 2016 - 11:26 PM

72000 sheesh thats redline yeah

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#12 _Agent 34_

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Posted 21 July 2016 - 08:39 AM

:stirpot: i asked for it with this one.

thanks gents. nice commentary.

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#13 _STRAIGHTLINEMICK_

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Posted 21 July 2016 - 01:18 PM

Yep as johnno said if longer rods and lighter component's are used then filling the block isn't necessary.

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#14 TK383

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Posted 21 July 2016 - 02:22 PM

Filling the block helps with ring seal - stiffens up the bores, less flexing = better ring seal = more HP, less blowby & longer ring life.

Also damps harmonics that can lead to stress cracks.

I'd fill it.

I fill just about everything serious I build, pretty much no downsides for a short fill. You can feel the extra rigidity in the bores just honing the block, the bore do not 'push' with the hone - you can go closer to finished size before letting it settle to recheck where you're at, after settling they do not shrink as much as ungrouted blocks & you do not get as much variation from deck & crankcase ends of the bore compared to the middle - without a fill the more rigid top & bottom of the bores hold their size better while honing, but the middle moves around with the pressure/heat of honing & you have to stop & let it settle to see where you're really at.

If the bores move that much (can be a solid .0005", sometimes more) from just the pressure of hone stones imagine how much they move under combustion pressure.

I'll usually fill to about 2" below the deck face on most engines, but a holden 6 you can't fill that high due to the water pump, you can fill above the water pump hole tho - put a plate over it & fill about 1" above the bottom of the pump hole. Once the grout has cured you can get in there with a die grinder & grind out the grout that'll interfere with the water pump.

Loss of coolant capacity is no biggie, never had a hot runner even with some pretty tall fills - all the cooling in the block happens within 1.5" of the deck face, so long as you make up the coolant volume with larger end tanks on the radiator you're golden.

You also should run an oil cooler - the oil will no longer be cooled by the water jacket & will run hot without a cooler.

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#15 _STRAIGHTLINEMICK_

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Posted 21 July 2016 - 04:42 PM

Fair enough but ive never had an issue without filling them either. The root cause is the reciprocating weight and short rods .Once that Problem is addressed properly the blocks dont seem to crack.