4g61t.org

I'm posting this here since this is my first post and I don't really know much about the 4G61 platform, so I am hoping that I am not making a fool of myself.

I come from a 4G63 background and I have recently become very interested in the issue of increased oil pressures seen in the 4G63 engines following a rebuild. Now I know it is well established that in almost every case that this phenomenon occurs, the culprit is the removal of the 4G63 balance shafts which accounts for a sharp increase in oil pressure. Now people have had varying amounts of success in addressing this issue by porting the oil filter housing pressure relief valve and using Kiggly's HLA pessure relief distribution block at the head.

What I am here for however is to ask you guys specifically about the 4G61 block. When we remove the balance shafts from the 4G63 we use a balance shaft eliminator kit which is essentially just an oil pump shaft for a 90 Mirage without the rear shaft attached. So, if the oil pumps on the 4G63 and 4G61 are the same (as I've been told!) then since your engines came stock without balance shafts, you should all be seeing the same insane oil pressures that we see when we remove the balance shafts. I just find it hard to believe your engines came stock from the factory like that.

If any of you have logged oil pressures, I'd be interested to know what pressure you guys see at: -

Cranking on a cold start
Idle
Cruise
WOT

If as I suspect you are not seeing 100+ psi on a cold start and 140+ psi at WOT could anyone who knows these engines suggest how the 4G61 block regulates oil pressure without balance shafts?

Are you sure the 1.6l oil pump gears are the same? I thouht I read that they had straight cut gears?

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05 wrx wagon
99 Benz ML 320
91 eagle summit swapped - 6/4 bolt combo
94 Audi s4 - sold
88 Eagle Vista Turbo LX sedan, RIP

Same front cover just bits plugged and the stub in place. I am almost 100% sure the gears are all the same and that the only change came with the 2G style pumps, in 2G 4g63's. I've racked my brain wondering what the difference may be as well, that would create the pressure difference. The 4g61 and 4g63 share the same rods, bearings, and block (minus a little deck height), and possibly the oil passages that would normally get fed for the balance shafts. I wonder if the oil pressure readings are available in any of the shop manuals for the 4g61 or 4g67 motors over at the manuals link: www.lilevo.com/mirage/

I know that the 4g61t oil filter housing is different than the 4g63t's. Maybe the differences control pressure in some way (speculating). I don't even believe we have a oil-water cooler on ours, can someone confirm this?

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4g61t.org
4g61t.com

No oil cooler, much like not having a factory intercooler installed either. Only cooling the car receives for fluids is the rad, ac rad, and the power steering cooler tube that runs along the bottom of the radiator support and back to the pump.