So ran my new b20 vtec motor for the first time this weekend. Vtec is disengaging on high g corners mostly right hand turns and high load corners.
Oil pressure stays up but does dip from 75 to 70 when vtec stumbles.
Looking for any insight. heres the motor
B20 block rs machine pistons,arp rod bolts stock rods, 98 ITR head cams etc..
Oiling system ITR oil pump and pickup. Moroso 20910 oil pan, catch can system vented rear of block one vent to can and one as drain back, valve cover to can, Catch can vented to atmosphere. 3 quart accusump.
Vtec lines are 4an, line goes from sandwhich plate to T fitting to gauge and head for vtec oil supply.

I plan on redoing the catch can and having both of the back block fittings to catch can and a drain back into the pan, Also adding more venting to the valve cover. I don't think crank case pressure is the whole situtation, but i thought i had covered all the oiling bases, should i SHIM the oil pump is so how much.

 

I thought most ls vtec setups had 6an feed to the head. I would up the size of the feed and source your pressure from somewhere else.

-Drew

 

Be super dave and start here.

https://honda-tech.com/forums/road-racing-autocross-time-attack-19/search-2631268/

You arent the only one that this has happened to.

 

Did do the search thing, even before building. Ie why i have the moroso oil pan and accusump. 6an may be the answer for supply but if pressure is the issue you would think 4an would yield more pressure.

 

there is a b20 only site that might give you more information...

 

try putting enough oil inside the engine... u do know that oil pan u have holds more oil then stock.

 

Where are you taking the pressure measurement from?

 

does ur moroso pan come with a baffle?? On hard corners ur oil goes to one side and the pickup cant grab any oil and rhat cuts ur vtec out. I had this problem in my em1 and ended runnin on 5 quarts. Problem solved

 

Moroso pan is the road race pan with baffle and 6 doors stock pickup. Oil pressure reading is obtained from from a t-fitting, line goes from acuusump sandwhich plate to t fitting for gauge and then out to the head to supply vtec pressure. Gauge is electric may switch it to my mechanical one for more accurate reading. Oil level was measured on stock dipstick and is overfull half a litre. Total system has 8.5litres in it with 3 quart accusump 5w30 mobil 1.

Is the level with the moroso pan too low???
Thinking 5w50mobil one???
No answer on shimming the pump???

 

I think the larger feed (6an) will yield more pressure inside the vtec system once it is restricted down to the internal oil passages. the 4an might yeild higher line pressure, but volume is also part of the equation, but i am not at all smart enough to know the specifics of it all.

I don't think the level of the oil with the moroso pan is too low. if using stock pickup and dipstick then i think that all jives. Can being overfull by .5 liters be causing any problems?

If it is all working while driving in a straight line i'm not convinced the thicker weight oil will help. same answer for the pump shimming too.

Has the accusump engaged at all during this?
Has vtec worked completely with this build or is this the first go-round? ie-could something have been assembled wrong and it's causing problems?

-Drew

 

Had the same issue this weekend, lost vtech while cornering at Summit Point - Main Circuit. Turns out I was low on oil. I'm an idiot, but I also hadn't planned on running the Civic this weekend. I just got back from Monticello, NY Friday night and my M3 had boiled the fluid on track (needed to be changed), so I drove the Civic for the first time on track Saturday.

BTW - is 5w30 the preferred oil to run in a K24/K20 motor on track? I run 15w50 Mobil 1 in the M3.

 

anyone ever stuck an oil pressure sender at the vtec pressure switch?

 

Volume is your problem. The VTEC heads need a fair amount of volume to keep the pins engaged on the rockers. Go to a 6an line and see if that fixes it before doing anything else.

 

I would think that too, but if that were true you could sit still and rev it while watching the scanner and the pressure switch would drop out as you rev it.
Basically, it should do it in a straight line where you are revving more than a turn.

 

I like the 6an thought and will do but here's my current theory.
If the crankcase pressure is pushing oil out and filling the catch can on corners the level drops and no vtec. Catch can drains back, level up vtec re engages.

So i come back to b20 road race crankcase ventilation issues, since this motor is hybrid and doesn't really have proper crankcase ventilation what is the best way to vent the block for roadcourse, Do u still use the ports on the back of the block or just vent the heck out of the valve cover, I routed the valve cover line just to a water bottle and very little mostly vapor into it. But under hard cornering the rear vents will fill the catch can thats why i made one a drain and one a vent.

New design is both to the top of catch can and drain from bottom back to fitting on oil pan.
Comments please.

 

that is basically how I'm doing mine. Like Endyn's. But he has both ports going to the can with a T in on of them for a drain. I will look for that pic again..

the bottom of this page http://www.theoldone.com/articles/badtothebone/
he has an elaborate system, but I am just sticking with the rear setup.

 

If crankcase pressure is the culprit, why would it vary in corners vs. straights?

 

The link shows exactly how i have my breather system plumbed.

I am going to convert vtec lines to 6an. replumb the drain to the pan and use both from the back of the block and add more venting from the valve cover.

Switch the oil to 5w50.

Pull the pan and inspect the bearings to make sure i haven't damaged it.
Oil level was always .5 litre overfull before going out so i can only assume that the level was changing with the catch can

 

If you were pumping the oil into the catch can, you would have seen low oil pressure when the vtec cut out. You didn't, and as Stinky said, you'd have seen the problem on the straights too. Fix the volume to the head first, then see about the other changes.