Some times after repeated revving at 8500 rpm when i release the throttle oil pressure readings on the gauge jump from the normal 75 psi to 90-100 psi, then after 15-20 sec. come back to 75 psi or immediately if i push on the gas again.

On B-series oil pump is fastened on the crank and since the phenomenon clearly appears to me to be connected to a load change at the crank, i was thinking it could be a symptom of a play in the oil pump.

Did someone experiment the same?

Maybe is time for an oil pump replacement.

 

I would be more worried if the oil pressure dropped after your repeated revving to 8500.
It might be that things are getting hotter and thus restricting oil flow temporarily, thereby increasing the sensed pressure!?!

 

No because during extended time at high revving (over 6000 rpm) oil temperature goes up from the normal 190-200 F° to 230-250 F°, pressure drops from 75 psi to 68-70 psi but still jump up to 90 psi and more releasing throttle...

 

I still wouldn't worry about it unless the pressure was dropping drasticly, and not increasing as you say.

How long does it stay high?

 

If i rev engine again oil pressure goes to normal quickly (3-4 sec.), otherwise i have to wait 15-20 sec.

 

By "releasing the throttle", do you mean enough to let it go back down to idle?
What weight oil are you using, and I guess this is once the car is fully warmed up (and which type filter, does it have a oil bypass type spring assembly within)?

Is this going into and out of VTEC?
This last point might be significant since VTEC is activated by oil pressure ....

 

where is your oil pres sending unit located?

 

Oil pressure jumps when i'm still in vtec, but some times also when in the low rpm (3000-4000) i open the throttle then close it without let the engine go back to idle.
The oil i use is Shell ultra 5w40 full syntetic that burns very slow.
Filter is stock Honda and temps within the operating range.
And this started to happen when the car passed 50k miles, before never.

 

Oil pressure sending unit is located at the end of tube 20 inch long fitted in the block where the stock oil pressure sensor was.

 

Well Paul, I don't know what to say, and I've never heard of this problem before (then again most people don't have oil pressure sensors).

Somehow I keep thinking more in the way of valvetrain/VTEC solenoid.

Good luck.
When I was in Rome a couple years ago all I mostly saw were scooters .... hehe

 

I think the problem is releted to some play in the oil pump... and to crank flexions under load changes.

SGT where are you?


... hey, if you'll came here again give me a phone

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by paulITR &raquo;</TD></TR><TR><TD CLASS="quote">... hey, if you'll came here again give me a phone </TD></TR></TABLE>

That would be nice, though I'd like to spend some time on the speed limit free portions of the 'bahn next time I cross the pond.

Steve's been really busy lately, and doesn't post much here any more.
Try e-mailing him, something like steve@sgt-racing.com, but check his user profile to be sure.

I don't really think the crank flex/oil pump scenario is the winning bet.
Might me more like obstruction of or changes in flow, thereby manifesting it in changes in pressure.

How many more guesses do I get.
Normally oil pumps are good to 400 whp or so, which is why I've upgraded to an aftermarket (Toda?) oil pump.
But even there, the issue was more of the gear/pump shattering because it is made of "sintered metal" (i.e., fromed from powedered metal particles at high temp and pressure, I believe), and not billet like the replacement aftermarket parts.

Ed