I recently purchased a motor which currently has 2.4T casings, 2.4E crank, 2.7 pistons, additional front mounted oil cooler and dc40 cams. Currently it is in bits, and whilst I’m searching for a new crank I was hoping to make some upgrades to make it more efficient and run cooler as going to be a track car.
Do I need to upgrade the oil pump given additional work required for a front mounted oil cooler, (already have the later pump). The casings have already had the oil bypass mod?
Finally has anyone had any experience of the modifications below?
hot66 wrote:Can’t go wrong with an uprated oil pump. Some even fit gt3 oil pumps to their aircooled builds
other options include a turbo pump, if you can find one.I sent my SC pump to Glen Yee motorsports.He does some trickery, which apparently yields 10/15% increase in flow rate,plus checks to spec for a fairly reasonable outlay.
Well worth buying the huge Bruce Anderson book on aircooled 911s, so much is explained and more importantly verified.
If you are increasing rpm then rod bots etc need upgrading, but so much more does too....
When I looked hard into this for my 3.2 it quickly looks like a financial slippery slope.
73T 911 Coupe, road/hillclimber 3.2L
Lola t 492 / 3.2 hillclimb racer
Boxster 987 Gen II 2.9
My 2.7 based on 2.4 cases was built last year and produces 271 BHP on a dyno ( high compression twin plug high butterfly GE 40 cams). I had the usual case mods:
Oil bypass, later (SC) oil pump, case savers/ time cert ( at your option), decks skimmed, spigots trued up ( after time certs) and modified cooling tin ( as per your illustration).
I did not half moon the cylinders and did not boat tail the strengthening webs. The logic behind not doing the boat tailing was that mag cases are not particularly strong and lack the rigidity of an aluminium case. A 40+ year old case is not the same as a new case from a rigidity point of view. Indeed caes tend to 'collapse' a little in the centre requiring deck skimming. Boat tailing potentially reduces case rigidity but people do it all the same. The notion being that boat tailing and half mooning reduces windage. The argument here is about physics and mathematics and is beyond me. I took advice from Chris Flavel who had a PhD in metallurgy was excellent at maths and understood the physics involved. He maintained that there was little to be gained. He did however say that windage could be reduced by knife edging the crankshaft. I did not do this either.
If you use a later pump then the mesh filter on the pump does not allow you to fit a standard 'sump' plate. I used a cast aluminium one which is shaped to clear the oil filter mesh.
The heads are important so I had them 'gas flowed' on a flow bench and the combustion chambers matched. Ensure induction ports match for size whatever induction manifolds you have and the same with exhaust ports and exhaust headers. A nice no heat tubular headers with lambda ports carefully positioned. A good free flowing exhaust.
I run high compression pistons (10.3:1) but this requires twin plugs. A compression ratio of around 9.8:1 or less should work with a single plug. Bear in mind higher compression generally requires higher octane fuel: the future of which is uncertain.
You might also consider shuffle pinning the cases. I did this on the 2.7 but not on my recent standard 2.2 S rebuild. Shuffle pinning can go seriously wrong if not done by a very competent person. The idea of shuffle pinning is to prevent the two case halves moving against each other (fretting) at high revs. Some say shuffle pinning is just another reason to spend money and make a bit extra for an engine builder. The issue with shuffle pinning (inserting dowels), as I see it, is that to pull the two case halves together one half has to have a clearance for the dowels. If there is a clearance, albeit small, then the case halves can still move. As far as I know Porsche did not use shuffle pinning but did use a special through bolt on competition RSRs to achieve a similar result. However, these engines were running at very hight RPM over long periods of time.
A lot of the above is fairly straightforward engine tuning stuff which you are probably aware of.
