Weird oil pressure issue
Thread Starter
Teching In
Joined: Jun 2019
Posts: 7
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Weird oil pressure issue Haven't posted on here in a while but I figured I'd post this on here seeing as this forum is more active than the GTO specific one. I've got a TSP 402 rotating assembly in an aluminum LS2 block with an LSA blower in my 06 GTO. Its currently with the tuner after being broken in and he called to let me know of a weird issue he's seeing on it. Oil pressure is rock solid at cold and hot idle, 50psi cold and 30psi hot. At WOT though, the oil pressure climbs up to about 4500rpm and then basically plateaus at 50psi. At higher rpm it doesn't drop off but it doesn't get any higher. I called Texas Speed and they couldn't really give me a whole lot of direction on where to proceed to diagnose. I had a local shop blueprint and assemble the short block for me, mains were set to .002" as were the rods. It's got a Melling 10295 in it too with the preinstalled spring still in it. The oil pan that's in the car also doesn't have a DOD relief valve in it so no need to plug anything there. Any ideas on how to proceed? It doesn't really sound like a bearing issue to me seeing as idle psi is good, plus after engine break in and prior to taking it to the tuner I cut open the oil filter and didn't see anything other than usual first startup dust. I'm thinking it's likely got some sort of internal oil pressure leak but wanted to see if anyone else had experienced similar issues before I get the car home and start tearing back into it.
Have you verified with a mechanical gauge? I'd do that first. I wouldn't worry about 50 with a loose motor. My factory gauge on my 99 when hot only goes to 50ish at WOT with a little looser bearings than what you have (.0025 on rods and mains), but the mechanical gauge shows high 60s usually. But I also put the beefier spring in it (same 10295 pump). If I'm really hard on it at the road course, my factory gauge wont even move or go over 40 psi. But the mechanical shoots right up as expected.
Thread Starter
Teching In
Joined: Jun 2019
Posts: 7
Likes: 0
Haven't verified with a mechanical but HP Tuners and my aftermarket gauge are within 5psi of each other at wot, which makes sense considering the different locations of the senders. I know it doesn't seem like too big of an issue but both the tuner and Texas Speed themselves believe it's a problem so I'm worried about it as well, especially with it being only .002" on mains and rods. Either way it seems like I've got to get it all apart to at least check everything over.
