3.6 oil pump into a 2.4 case ?

[herman maire]

Could use some advice again.

If you were rebuilding your 2.4l engine, and you had a low miles 993 3.6 oil pump sitting on the shelf, would you guys recommend fitting the low miles 3.6 oil pump or just refit the original pump with unknown miles.

I inquired about this quite a while ago and have read treads from engine builders that automatically upgrade the oil pump to 930 pumps , 3.6 pumps then to gt3 pumps.

The original 2.2 Oil pump I have does look to be in great condition as well ( impellers are all shinny)

Can this pump be made to fit into a 2.2 or 2.4 case with 70.4mm stroke crankshaft .
Seems pretty massive compared to stock 2.2 pump.

This engine will be used mostly on the street and fun track days .
Would really appreciate some advice on this.

Also, can stock 3.6 pump screen be made to fit in case.

Thanks you 🙂

[Walt Fricke]

You need to clearance the case, because the big pump will bump into one or two bearing webs. I did this on one case with a hack saw to get the biggest chunk off, and a die grinder to finish. You also need a shorter splined tube to connect to the IS. The 3.3 Turbo used that part, and I think later engines.

I'm sure the sump screen (attached, not detachable) will fit, or you can purchase a suitable sump plate if there is a clearance issue there. A dished one from a late 3.0? Aftermarket deeper sump plate?

Kind of overkill for the purpose? But I put a GT3 pump into my race 2.8. An SC pump works fine in that application on another of my 2.8 motors. Hard to be totally logical.

[herman maire]

thank you for taking the time to help me out, really appreciated.

Ok so the pump does fit once come clearance is made. I have the original 993 intermediate shaft, it seems pretty short but I can measure it.

I was talking with a aircooled engine machine shop in Nevada, sounds like a lot of customers keep the original pump but a lot of customers upgrade to larger pumps as well. they recommend to
cross drill and grove the center main on the crankshaft. Not sure if that will lower oil pressure a bit.

Don’t want to bother you but is there any chance you have pictures of when you modified the case to fit the larger pump. After the case is modified, Can you fit the original pump if needed.

Do you notice any difference between your engine with gt3 pump and sc pump.

[Walt Fricke]

There is only one short shaft, so if you have one shorter than what was in the engine, you are all set there.

I actually had low oil pressure with the GT3 pump. Not sure just why, but when I get the engine going again I will lay out a bunch of $ for the special oil pressure setting spring and cap the GT3s have, to see if that helps.

Since the case modification creates more space around the oil pump, of course you can put a shorter, earlier, pump in.

Cross drilling calls for a crankshaft shop - that steel is super hard, can't do it with a drill press at home. You also need to groove one set of bearings - the two shells which go into the center/crossdrilled main. That is a better mousetrap than grooving the crank journal - less expensive, too. The shop which does the crank ought to be able to groove the two bearing halves - calls for a lathe and making a jig/holder for the shells which can be chucked up.

But that stuff is race engine, 8,000 rpm stuff - way overkill for an older street car with a mag case, even if it sees some DE track time or is autocrossed. No power above 6,000 rpm anyway..

You can figure out what clearancing is needed by careful fitting of the pump in place before you do anything other than clean the case - which you will have to do after you are done with your die grinder or whatnot also anyway. Check both case halves. The one with the studs is, of course, the easiest as they locate the pump. I can't remember what, if anything, I did with the other case half, but if some case webbing was hitting the pump, I got after it.

Better is to have a machinist do this with a mill or other suitable tools - looks cleaner and more finished (until you close up the case).

[mikedsilva]

Originally Posted by Walt Fricke

You need to clearance the case, because the big pump will bump into one or two bearing webs. I did this on one case with a hack saw to get the biggest chunk off, and a die grinder to finish. You also need a shorter splined tube to connect to the IS. The 3.3 Turbo used that part, and I think later engines.

I'm sure the sump screen (attached, not detachable) will fit, or you can purchase a suitable sump plate if there is a clearance issue there. A dished one from a late 3.0? Aftermarket deeper sump plate?

Kind of overkill for the purpose? But I put a GT3 pump into my race 2.8. An SC pump works fine in that application on another of my 2.8 motors. Hard to be totally logical.

Hi Walt
what about a 993 pump into a 3.0 SC case.. do they need to be clearanced too?

[colingreene]

Yes it will.
I have a 930 pump in my SC case and a 964 pump in my 7R case.
They both need to have some work done to them to make them fit. Nothing crazy though.

[mikedsilva]

Originally Posted by colingreene

Yes it will.
I have a 930 pump in my SC case and a 964 pump in my 7R case.
They both need to have some work done to them to make them fit. Nothing crazy though.

Intersting, i fit the pump to the right side and it seemed to have approx 1mm clearance already.. I didnt fit the other side to check so I had better do that too.

[herman maire]

Thank you again Walte for your reply, really appreciate you sharing your knowledge and thank you to the other replies as well.

I’ll leave the crankshaft stock then if it’s overkill for a street car. I’ll move forward with fitting the 3.6 oil pump if I do run into problems it’s good to know I can fit the stock oil pump or an sc pump if needed.

Crazy question, any chance anyone has the torque specs for the 4 nuts in the 3.6 magnesium pump. I took mine apart to inspect and now not sure how tight to tighten the 4 nuts.

I look forward to the replies to your question mike for your 3.0l engine. Seems like 1mm clearance would be sufficient.

['78 SC]

I installed a 964 pump in a 930/16 case ('82 911SC) without modification. Don't know the definitive history of the engine, but I doubt it had been opened and modified. Had a standard 4-rib 911SC pump in place.

BTW, oil pressure is very good, but the most noticeable change is the way the oil level in the tank (as shown on the standard gauge) recovers after running at higher RPM. I attribute this to the much larger scavenge section and probably the improved pickup.

[Walt Fricke]

Herman
I once disassembled and reassembled a pump with Grady Clay (legendary Porsche mechanic/shop owner/racer/writer and teacher of all things 911, RIP). I don't recall using a torque wrench. Small fasteners, typical wrench for the size limits how much torque you can apply.

But you can find out what standard torque is for the size of bolt/nut: diameter and thread pitch (use your thread gauge tool for that). Maryland Metric has a chart, I think, but googling torque specs for bolts or something like that will get you the info.

There is very little pressure in the pump trying to push its parts apart - not a critical value like rod bolts.

Mike and '78 - The only SC case I have put a bigger pump in was a '76 (Carrera 3.0 and early Turbo, 6 bolt crank). It needed clearancing for the GT3 pump. Maybe when Porsche changed the case for the '78s and later (9 bolt crank) it changed the webbing? Early sand cast cases for sure need clearancing, as do the mag cases - I put a 930 pump in one of those once, and a shop did the clearancing and other work.

A millimeter of clearance is as good as a mile. Zero clearance between non-moving parts might be enough, but a bit of clearance makes everything easier to install and avoids manufacturing tolerances, expansions, etc.

[Rosco_NZ]

Who has the setup to groove a pair of main shells? What might it cost?

['78 SC]

Just for reference, here's a 1983 911SC case. I don't think the webbing has been modified from stock. Note the web that Walt had to trim is already relieved.



I'm going to put a 964 or 930 pump in this. I'll report back here any issues.

[Walt Fricke]

Rosco
I know for a fact that Rudtners (google, New York or environs race shop) has the jig for this.

However, any machine ship with a lathe and skills could do it. You have to make a cylindrical holder, and it should be in two pieces held together with bolts so the shells can be inserted, the jig tightened so they won't move. The jig needs to be attached to a mandrel or whatnot which can be held in the jaws of the lathe. Then you insert a boring bar with a sort of 90 degree or whatnot angle on its end, and start moving it off the centerline as it cuts.

Might be easier than sending shells to the States?

[spyerx]

996 turbo pump on a 2.7 case

[stownsen914]

Grooving a pair of main bearing shells is not expensive. I just had a pair done. Might've been $40?