r33_racer

Like the external oil feeds bobby. Those banjo's wont foul on the back firewall?

Fully sic uleh? Return to stock!

I use rb26 headgaskets on rb25/30det without any issues.

I was thinking if you could achieve say half inch of lowering engine towards sub frame via engine mount mods and then lowering sub frame half inch off chassis rail then you would be pretty damn close and both of those things are very straight forward and have probably been done before. But as you said you would need to look at drive shaft clearances and angles.

I heard of a trick using rb20 engine mounts which lowers it 10-15mm. Though dont know how accurate that is as I havent done it myself. How much lower would the engine need to sit in order for the timing cover to not hit the bonnet bracing? Would 20mm drop be enough?

Time to pull it all down again then if you want to fit the collar.

Then combine an engine with lots of overlap and a greater then 1:1 exhaust to inlet pressure ratio and you get a whole lot of exhaust gas reversion and residuals left in the chamber! If your hot side is going to be restrictive then don't opt for cams with large overlap windows. It ain't an atmo v8 here where large overlap is required for high power/high rpm.

Run it without any shims and see what pressure you end up with and then go from there. It is an external adjustment with a Tomei pump, so you can add shims after if you need more oil pressure. The old rule of thumb for oil pressure is 10psi per 1000rpm. But its cool if it goes higher. So long as its with in 70psi-100psi hot then its fine. If you are revving it high-ish (over 8000rpm) then aim for a higher pressure closer to the 100psi mark. Almost every other pump has its pressure adjustment inside the engine where you cannot get to it. Hence why it needs to be set right first up. The Tomei pump is a superior design, you can adjust the pressure accordingly whenever you like

90mm bore. that is really pushing it in terms of wall thickness. If you run a 3mm wall, all the bores will be touching or close enough to it. Is that roughly what you have worked out?

Your manifolding, camshaft choice and turbo choice will help determine what revs you end up taking it too. I will be suprised with the turbo you said you have or are using you will need to take it much past 7000-7500rpm. No reason to keep on revving if you've past peak power. But I guess you will find it all out for certain on the dyno.

And that statement couldnt be more correct!

I dont think your gauge is upto scratch. You may need to get another one or exchange it to compare results. It is not making any sense.

Sorry mate, meant as a question. Ok cool. Will be interesting to see what kind of leak down an old CA has.

Factory RB25 headbolts have a M11 thread on them, though they do have a reduced shank (down to 10mm), though from memory the ARP studs are also slightly reduced, I dont think they are bang on 11mm OD. Even being 0.1-0.2mm undersize is going to increase the CSA substantially and also the supply oil flow potential, however it seems the block restrictors are the biggest inhibitor of flow, not your head stud hole clearance.

You definitely have more then 100psi coming in from your compressor too when checking and are you certain you are holding it on TDC on whichever pot you are checking? I know when we do it, it can be difficult to hold the piston at TDC accurately when waiting for the leak down gauge to stabilise as the pressure builds. Once you have the gauge reading properly let us know what you get. But typical issues would be there for sure given the age of the engine. Rings would need replacing, valves and valve seats would be carboned up and leaking. Good chance valve guides and valve guide seals are shot and they too can be a cause of leakage. If you spat 2L of oil out then its more then likely a blow by issue from the lack of ring seal.

KiwiRS4T - Is there any baffling or gauze inside your catch can with the crank case breathers plumbed into it? Or does the venting blow by pressure have clear access straight to the moroso breather cap?

There is the main culprit sorted for starters.

So they would both be working as vents then. I have a similiar setup on my car. I have two dash 10 vents off the inlet side of the sump.

So you have one breather from the inlet side of the sump and one from the exhaust?

I will be surprised if that is the issue lol. Unless you are running larger studs and the machine shop didn't drill out the head stud holes big enough....

You would be suprised how many non diesel engine cars use diesel oil. It wont harm your engine. If may even help if your lifters are sticky from excessive carbon build up over the last 15-20 years. As far as im aware, the only significant difference in most diesel oils is there extra cleaning and suspension additives as their oil gets dirtier quicker then a petrol engine and usually have longer service intervals. Just get a viscosity thats close to what you are using now, or abit thinner like others are suggesting. Either way your not going to find out anything by just speculating or waiting for someone to give you the answer you want to see.

Go external pump setup.

Okay... You havent maybe restricted oil flow to the cylinder head too much or something funny? Are you running aftermarket valve springs?

When your head was reconditioned, were the lifters disassembled and cleaned or even looked at? There is a good chance they are carbon'd up or buggered. That would be my first port of call, drop the timing belt, pull the cam covers off and remove the sticks and inspect them all. Unless your head was grubscrewed when it was cleaned, you would have to drill and tap into one of the oil galleries in order to 'T' off a signal line to measure oil pressure through the head.

MRHD66, What turbo are you planning on running?