4a block strength

[30psi 4agte]

i want to know how hes splitting blocks!
i have NEVER heard of anyone doing that.
even on 400hp+ engines running 25+ psi.

Its fairly common hey..

I know of 3 different people now who have done it.One of them have has done it twice.

[takai]

Yeah, but the head/combustion chambers would get nasty..

I was thinking about this earlier. If you were paranoid about the cast iron strength around the top deck, you could always grind the whole deck off and replace it with a machined steel plate. I can't be stuffed going out to the shed to measure it, but I think you could you could probably go to a 5mm or so plate.

This would also give you the chance to adjust deck height to get the exact compression ratio you want.

Yeah, i reckon you could probably go a bit more than 5mm as well.

Revvy: i bet he was using 3 rib blocks, ive seen a 3 ribber crack under NA pressure.

[Mr Revhead]

can we get pics? details of engine specs etc?
in all my years of dealing with 4ages iv never heard a first hand account of a 4age block failing.

[takai]

No idea of specs of this engine, was in a clubman which was out at Collingwood in late 2005. Spilled its guts just over the top timing line, split the block down cylinder 2.

[30psi 4agte]

can we get pics? details of engine specs etc?
in all my years of dealing with 4ages iv never heard a first hand account of a 4age block failing.

Its up there with mine... As far as hp and boost goes. Prob even more hp to tell the truth.

I believe it is using a T66 and 30 psi.

Will post a pic soon.

[30psi 4agte]

This is one reason i have said to build a gutsy 4a youd want to keep a std size bore !

The omre meat you have in the bore the better

[takai]

I wouldnt mind seeing what a 4A would do if sleeved down in bore size. The stock Yamaha R1 pistons are pretty light and would be roughly the right size, i think the limiting factor would be the head and the crank.

Bah, just chuck an R1 engine in something....

[Ben Wilson]

I wouldnt mind seeing what a 4A would do if sleeved down in bore size.

I'd think you'd get valve shrouding from cylinder wall interference.

[allencr]

Is it the same cyl & spot both times? #1 intake side next to the pump stays the coolest.

I don't see the sleeve as increasing the block's strength, but reducing it! It's not like multiple layers of iron, even if the sleeve is better quality then the block, is comparable to something that is strengthened by laminating - bonded together with its grains on a bias.
Its been bored, weakening it, then it's gets a 'pre-load' & is trying to expand from the pressed in sleeve. Boring the sleeve to size lessens that 'pre-load', but I doubt that it is cancelled out by better/different material, let alone increasing its strength by much.

Isn't there some self-hardening goop that drag racers strengthen their water jackets with?

I have no experience with sleeves, turbo/super chargers and cylinders cracked by something other then broken rods.

[Ben Wilson]

The sleeve is steel, the block is cast iron. Cast iron is great in compression, but lousy in tension. Steel is good in both.*

Stuart can correct/carry this simplification further until you brain explodes quite easily.

[oldcorollas]

sleeves are usually cast iron... reason being that the graphite bits (flakes or nodules or whatever) in the cast iron provide lubrication.. or site for oil to sit for lubrication if the carbon goes...(seems from site below they use SG = spheroidal graphite cast iron)

this Darton site has some reasonably good info for the tech oriented... and might be worth an email regarding the use of sleeves in the 4A block..
http://www.dartonsleeves.com/ductile_info.htm

the block is also cast iron, but they are not made with composition or process that will impart greatest strength to the bore...
a) it is cheap
b) it usually works and is cheap

with a sleeve, they are (often) centrifugally cast, which gives homogenous properties and reduces defects (which reduce strength).
they can also heat treat to get the best properties from the sleeve, without worrying about the rest of the block in terms of warping or whatever.

i forget if they use SG or grey iron for the block.. but SG is stronger and is used for steering parts and diff housings etc....


basically.. block and sleeve are both cast iron... but sleeve is optimised cast iron

[Ben Wilson]

There you go, I sit corrected. I'd assumed they would do the sleeves out of steel, but I forgot about the self lubricating qualities of cast.

Is Ductile Iron, then, Basically Steel with Graphite Spheroids Dispersed Throughout?
For all practical purposes, yes it is. The quantity of graphite is usually between 8 and 12 percent of the volume.

Damn, that's a lot of graphite....

[oldcorollas]

yup, a lot of graphite, but if it is in round nodules, and not flakes (grey CI) or cementite (white CI), then they don't actually affect strength as much as you would think.
of course size and number of nodules do have some effect, but that can be controlled fairly well, by composition of the metal and by heat treatment

[takai]

/me quickly shovels brain matter back into his ears. +rep

[rms]

If you are splitting cyl bores you don't have much option other than thicker steel liners.
Steel liners are used in many high performance and aircraft applications.

They are generally made from 4140 chr/moly with either a hard chrome or nitrided ground surface.

You have to run a bit more piston clearance and use plain iron rings. To run them in you really need a dyno, they must have load applied immediately or the rings will not bed.