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Rb30 bottom end

General Engine Building Discussion

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Hey guys just dropped my bottom end to a machine shop to have it all machined for assembly(finally decided to give another shop ago after loosing my last block and a fair bit of money to poor quality machine work).

I have 4 questions the 1st one is if anyone here has had first hand experience with grout/concrete filling blocks around 3/4 up the water jackets in a street engine or even better a rb30. The machinest said the i will not notice a difference in water temp but i feel like it is a little unnecessary for mid 30psi of boost i have not really heard of people using block fillers at that level in rb30s.

The 2nd queston is i dont know if i should plug the oil filter bypass valve or just replace it with a new valve people seem very 50/50 weather to do it or not. The machinest said he normally pulls the valve out and plugs the hole up. But my last engine had the valve in it still and it never gave any problems that i am aware of.

3rd how are people going about having a bottom end machined and checking it all to make sure its right with out the shit part of paying the money only to get the block back and its wrong or in my last case destroyed and having to deal with the "mate it will be fine just screw it together it doesnt matter that its 0.002" over top size we do this every day"(main tunnels all over the place full of taper and different sizes)

This machinest i am using now is a 3 hour drive away so will make it a little harder if this happens again

Also when a cylinder becomes distorted from cyl pressure what sort of shape does the cyl generally end up?ie. Egg shaped? Reason i ask is this is the reason the machinest suggests filling the block is to stop cyl distortion. Now when i pulled the last motor down the bores all had taper from top to bottom but were not so much "out of shape" the worst bore had 0.0015" of taper from top to bottom. But thinking it might have just been from a poor hone job in the first place as there was fair bit of dodgy machine work in the motor when i pulled it down

Cheers guys

I feel your pain with shit machine work. Had a horror run myself from multiple shops on my subaru.

1st shop took the best part of a year to close deck the block. Then i get it back and its beat to hell with dents all over the parting face and even into the main tunnel.

Then i go to another shop to get a line hone performed to suit ARP main bolts and fix the damage from the first shop. And the stupid fucks forget to tighten all the bolts when honing it.

The industry is a fucking disgrace.

I did read about your incident the other day sorry to hear mate it is unfortunate but seems to be a very common thing

Sorry for the late reply but I'll add my my replies here.

1. I've grout filled a number of blocks and for a street application I generally wouldn't bother. I've done a few street 4G63 engines that I've 1/2 filled and it hasn't been detrimental to the ability to control temp, however you also need to consider that the major cylinder pressure is occurring through the first 20-30 degrees of crank rotation so solid filling the lower half of the block isn't going to help too much with bore distortion. Ultimately it doesn't sound like you're trying to break any world records for power with the RB30 so I don't think it's justified.

2. The oil bypass is a bit of a personal preference. The majority of oil filters include a built in bypass inside the filter which is utilised if the oil filter media becomes blocked so for me it's a bit of a moot point.

3. The machining is a tough one. Really you need to start by finding a machinist that has an excellent reputation. This is tougher than it sounds but your local car club is probably a good place to start - Find out who is running high power engines and who they've used. I wouldn't accept anything that's 2 thou out of your spec from any machinist.

4. When a cylinder distorts from excessive pressure it will become out of round, or egg shaped as you've referred to. It's likely that if you're measuring taper in the bores that this is more in line with the boring and honing process.