Hi Bruce,

This all sounds so TB to me.

"I know that you can't successfully use a Bosch fuel pump made for a N/A engine on a turbocharged one ..."

How do you know?

"Can I use a Bosch 0 580 464 025 main pump (from a b230ft) on a b23 engined 244? Or will it deliver too much pressure and hurt my fuel injection system?"

It won't deliver too much pressure and it won't hurt your fuel injection system. But, will it fit?

The main pump merely has to exceed the regulator pressure and flow enough volume to keep up with your demand wide-open-throttle up the mountainside. With the regulator returning 90% or more to the tank, there's little chance of a pump not doing that given an unclogged filter, good input of fuel and electricity.

"I know that adding a higher capacity pre-pump (in tank) pump is typically regarded as a performance upgrade, but does that also hold true for main (undercar) pumps?"

It is indeed regarded as an upgrade to swap the in-tank pump with a more expensive one. By that, I think it gives the swapper a sense of accomplishment, but probably does nothing whatever to help the fuel system. It upgrades the bottom line over at IPD too. As long as the tank pump can furnish the main pump with a vaporless stream of liquid (which the stock pump is quite capable of) it is already upgraded to the max.

I'd say, if you have one, and it fits, put it in. What can you lose, compared to the price of a new pump? That is what I'd do. Next question: what makes you think the pump needs to be replaced?

--
Art Benstein near Baltimore

A man will pay $20 for a $10 item he needs. A woman will pay $10 for a $20 item that she doesn't need.