^what tires do you run?

 

I've done that several times and never had any issues.

 

looks very familiar.

 

I think these pressure drops will occur on just about all tires. anything 1G+ which now days these new street tires will do easily.

 

I'm on slicks.

I've observed that the thicker oil doesn't fill the catch can as quickly. (at this point its just a theory) It might even stay in the pan better. I'm thinking about go back to the straight Valvoline 20W-50 Racing oil. My rod bearing look fine after 2.5 years of hard racing and oil starvation.

 

Andy, I agree.
I'm not seeing much of a difference. before or after the underdrive gear.
It would be interesting to see a back to back with and without the accusump.

 

After closer analysis, I believe the following.

1. With the UD oil pump. It takes longer to recover oil pressure. (I don't know if I would recommend this for road racing)
2. It's plausible that running thicker oil is better.

However, there are three variables that may effect these results.

1. I didn't run the same oil viscosity.
2. I'm making more HP and this could drive up oil temps and further thin the oil.
3. My driving has improved since. On averaged, I'm putting down .2 G's more.

I'm starting to consider that accusump.

 

When I read the ad for the ud gear, it said it "allows more oil to be in the pan where it should be to protect the engine".
Is that a poorly-written statement or am I missing something? LOL

 

Well technical it should. When you remove the balance shafts, it increases oil pressure. Slowing down the oil pump will allow more oil to stay in pan and oil pressures to be more OEM spec. However, they didn't account for how much a 1 G right turn pushes all of the oil out of the pan. LOL

It kind of does concerns me that oil pressure doesn't recover as quickly. I'm really leaning towards installing an accusump and maybe even ditching the UD oil Gear.

 

that was my concern. i was thinking at startup, but figured it couldn't be that much of a difference. then i thought the same as you; recovery. i understand the need to get oil pressure back to spec after some specific mods, but this didn't seem to be a good way to do it, IMO.
i decided to leave my rear balance shaft in place (without the belt) and the front one in as well. i ran 125k+miles with it. i'm not making more than 350-400whp, and never run more than 7200RPM, so i think i'll be okay. all the worries about oil pressure doesn't sound fun LOL.

an accusump with a pressure switch sounds like a no-brainer, though. even on my tires.

 

To me, it looks like the underdrive gear is doing it job. Your lowest oil pressures are 40psi, while the other guys in here are dipping to 20psi. 40psi is almost acceptable oil pressure, and definitely a hell of a lot better than 20psi. I remember reading somewhere, something Kiggly posted, about the mains and rods needing 50psi to be properly/fully fed in the 4g63. He went on to say to account for pressure loss in the oil galleys, cooler, etc, seeing 60ish psi at the oil filter housing would be ideal, IIRC...

 

I'm comparing apples to apples. In my post, the top is without the UD oil gear and the bottom is with it. It's hard to see with out having access to both files. the UD gear appears to drops off faster and build oil pressure at a slower rate. This leaves the bearing unprotected for a bit longer. Its a good mod for daily drivers. Personally, I would not recommend using it for road racing.

Left is with UD gear -- Right is without UD gear



Blue is Lateral G's - Red is RPM - Green is Oil pressure

You can see it takes just a bit longer to get the oil pressure back up

 

so, the UD pulley doesn't drop as low but it stays at it's lower points longer?

then it becomes an issue of the lesser of two evils? 20psi for a short time or 40 psi for longer? speaking in general, i mean.

 

You can't compare his logs to mine. If you look at mine, the oil pressure is about the same for the most part.

If you you look at my recent image. The change over from right to left. If you follow the lateral G's, you can see where the oil pressure is taking longer to get back to a normal state.

The issue as we know it is when the pickup looses oil on the right hand turns and this is what causes the oil pressure drops.(not the UD oil gear) What I'm saying is getting oil pressure back ASAP is the key.

Don't get me wrong, it's a great part. Just might not be a good fit for Road Racing. Or just might require a better oil pan and accusump system to see it's full potential.

 

As an update on the Evo IV oil cooler vent. Ordered it from here:

http://www.viamoto.co.uk/proddetail....art+-+MR603498.

With shipping to the west coast it was about $72USD. They have to order it from japan so said it would take about 10 days to get to them and then they would ship it to me. Ordered on Sept 28th, delivered today on the 13th of October. They were very good on communication and updates and it was carefully packed. Not sure when I will get it on the car since it's going on with a track only OEM VIII bumper so won't be for months at least.