Oil bypass necessary?
 

I am rebuilding a mag cased 2.2 that was already converted to 2.7. All my previous experience is on newer cases so I havent seen this issue before.

I have a spare 82 3.0SC oil pump. I also have the early 2.2 3-rib pump from the original motor.

I am running an external 28-row cooler. This car gets used hard but not on the track anymore.

Is the "oil bypass modification" seen in many threads here, Bruce and Wayne's books necessary? I was hoping to put the 3.0 pump in and keep on assemblin'

Thanks for the help

John

The bypass mod is only needed if you use the SC pump. If you use the old pump you don't need the mod. They go hand in hand. The SC pump has a smaller scavenge pump and larger pressure pump than the old pump. If you don't do the mod and use the SC pump the crankcase may not scavenge properly and you could have the tank go dry.

-Andy

Thanks Andy. Is it acceptable practice to use the 2.2 3-rib pump with an external cooler?

Also wondering is it acceptable to run an external cooler on a 3 rib pump.

Thanks

There is an article on Klassik ATS that might be helpful to you.

You should call gt series one performance and talk to Glenn. He’s been rebuilding porsche oil pumps for a long time and he’s super nice!

Well I feel a bit silly. I should have read a bit more and wouldn't have to ask such an obvious question...my apologies 😊

1969 S on had a front mount cooler.
1970/71 T&E was an option.

2.0 and 2.2s used the 3 rib pumps...so it would seem ok to run a front cooler as the factory did.

C.

Thanks for the suggestion...was hoping to avoid splitting the case but if I do this is very helpful,

C.

Not strictly necessary but why wouldn’t you do it ..?? It’s a highly recommended upgrade for all early engine builds.

If you haven't split the case yet ... it's worth considering whether you want to. Does it need a bottom end rebuild, or are you just considering upgrading the oil pump/system? The act of splitting a mag case often causes it to warp, which means thousands of dollars in machining to rectify. Not sure upgrading the oil pump and doing the bypass mod are good enough reasons to go to that trouble. Just my opinion.

Exactly what I was thinking and why I was asking in the first place 😉

To answer the earlier q, yea it’s fine to run an external cooler on an early pump. I did exactly that on a 2.7L race motor that I ran for many years. Large front cooler using -16 lines.

Appreciate the response, great to know thanks 😊

C.

I bumped a 2.4 to 2.7, S cams, raised the compression, kept original pump. Had to install a front cooler as all of that raised the engine temp. Never occurred to me to contemplate compatibility, should have asked. But that was 25 years ago, still purring. Bob