Volvo introduced their 'higher' volume in-pan oil pump with the B23FT motor. Supposedly, all B230FTs and B230Fs also use that oil pump PN 1346144.
I have opened up a number of B230F motors and found that the oil pumps were NOT the 1346144 pump. But, all of the B230FT motors that I have opened up [from '85 to '98] DID have the higher volume 144 pump.
The 'standard' volume oil pumps have gears that are just under 1in tall.....~0.994in.
the 1346144 pump has gears that are about 1 and 3/16in tall........~1.182in.
There are some things that you can and probably should do to an oil pump if you want to optimise the flow......besides the usual thing of checking the clearances between the gears and the housing. When I prep a 144 pump, I do some porting/smoothing/blending inside the housing; as well as doing some things to make sure the clearances are on the snug side if at all possible.
[procedures for checking clearances are in the engine reconditioning green manuals.]
The AQ171C [basically a B230F block with a stroker crank and a 16V head] uses the same in-pan oil pump as a B230F. I've only opened up one AQ171, and I don't remember if it had a 144 pump or not.
Be that as that may be, the more important thing is to make sure that the oil flow...in VOLUME....is adequate. There are three places in a B230 block where there are restrictions that can impede volume flow. I put up a gallery on pbase illustrating those locations, and what I did to correct the deficiencies.
I checked to see if StenParner offers a high volume oil pump. They only offer their version of the 1346144 pump.
Back when Mellings came out with the M181, it was supposed to be a replacement for the 144 pump.....meaning that it is a 'higher' volume pump, in comparison to the B21F/FT and B23E/F oil pump.
The 144 oil pump was listed by Volvo as having approximately 15% more flow than the pumps using the 1in tall gears.
Re oiling to the 16V head on the B230 block: The B234F [and the AQ171/AQ251] all use the same HG as does the B230 motors. Meaning that the oiling to the head follows the same flow path from the block to the head past the second head bolt on the lower side....right above the oil filter boss.
There are likely a few things that you can do to make sure that there is an adequate flow volume path for the oil once it reaches the head. I'm reasonably confident that you can figure that out.
Whether you believe me or not, taking care of the in-block oil gallery restrictions does make a difference in how much volume actually flows. AND, it also results in higher line pressures.
....admittedly, the viscosity of oil used and the bearing clearances are going to have quite an influence on just what line pressures you will see. The thinner the oil and the greater the bearing clearances, the lower the line pressure you will see.
One area of restriction that no one has ever brought up is the restrictions in the oil cooler sandwiches and the angled extension housing used to relocate the oil filter/cooler sandwich further back along the block's side.
Porting the Wahler sandwich appropriately, and the extension housing appropriately, is worth 2-3 PSI line pressure at idle. BTDT
TF