3.2 Build Specs- Opinions Sought

[NickP]

Gents-

About a year ago I finished the build on my 72 ST tribute car. I certainly learned a great deal over the 4 years it took to finish the project. For various reasons the engine is based on the original mag case with 85mm pistons, its twin plugged, MFI and looks all business. It dyno'd at 202 at the wheels. Now I want more power and am looking for some advise and opinions on this plan. I'm planning on assembling the parts I need as they come available and I can swing the expense and to use what I can from my existing motor. I'm thinking about using a robust 3L alum case and heads (machined for twin plugs and whatever port work is needed/best).

So...using the MFI pump (but reworked by Mark Jung), the crank, con-rods (I think), oil pump, muffler, fan/shroud, twin plug distributor and electronics (I hope). I'd like to get 265-275 hp if that sounds right and do this in the most cost effective way I can by pirating what I can from my engine. Am I on the right track or nuts? And, how does this list of parts look to this educated group? Thanks in advance!!

Nick

3 Liter SC case
98 mm cylinders 10.3:1 CR
930 Turbo oil pump w/ internal mod for max flow
70.4 mm crank (from my engine)
Pauter con rods (from my engine)
ARP head stud kit
911SC heads (porting, twin plug and MFI injector port machining)
41 mm intake ports
39 mm exhaust ports
MFI pump mods by MFI Werks- Mark Jung
MFI Werks MFI Polymid fuel lines
Machined mag stacks 52 mm top 41.5 mm bottom. (52 mm velocity stacks and K&N style air filters)
Throttle housing rebuilt by Aaron Burnham 41.5 butterflies 40 mm ports.
High performance valve springs
Titanium valve spring retainers
Either my existing DC40 cams or? DC60?
Ignition wires w/ Bosch connectors
RSR plug wire holders (Glenn)
RSR spark plug connector holders (Glenn)
Burnham Twin plug distributor (existing, I hope)
Series 900 amber shroud and engine tin (existing, but probably not on a 3L case)
SSI heat exchangers (need thick flange, right?)
M&K muffler (exisisting)
Twin Bosch custom ignition boxes from Burnham (existing,I hope)
Two Bosch Coils (existing, I hope)
Bosch MFI fuel pump

[jpnovak]

Sorry, But your existing crank and rods will not fit in the SC case. The journal size is very different. The early 930 or Carrera 3.0 case would accept your crank and rods. But these are hard to find and expensive.

At this point, the easy answer is that anything inside the engine will be different (there are a few exceptions) and anything on top of/outside the engine will bolt onto a 3.0.

Your build spec is solid and will be reliable. Most likely you will exceed your target power ratings if built right. However, your pile of parts won't quite get you there.

[NickP]

Thanks Jamie, ahhh yes I’d forgotten about the crank difference. I do have a line on an early 3L 930 case that would work with my crank. I would have to source heads for that case. I also know of a 78 SC case that’s available to me. It’s a shortblock, so all internals are there. For a 3.2 SS as I’m considering would the port size from the 78 case be a good choice? I should have mentioned that my car is something like 85% weekend canyon duty, 10% around town, 5% track (4 track days last year). I want it to have good street behavior but still fun on the track. It’s like that now; the power is there from ~3500 to 5800 rpms, but on the track I’m not that quick on the straights. The handling is sublime, just need a little more oomph.

[MST0118]

I agree with Jamie that it’s the wrong 70.4 crank and rods but I think you can sell those parts to buy an SC crank 70.4 9 bolt and new Pauter rods. It looks to me like a good build and I personally would pick the DC60 cam if you’re trying to get that sort of power.

[trond]

i would go with lower compression

[Nux]

An easy upgrade could be 90mm slip-in Nickies to make a 2.7, gaining 20hp or so? LN engineering stocks 92 and 93mm C/P packages as well, but I think you'll need to bore out the spigots for that.

[lvporschepilot]

You'll get in the range you want by adding 92mm cylinders and DC60 or 65 cam, that's exactly what I'm running with similar ports but on ITB EFI. If you have a 7r mag case there's no reason you cannot continue using that.

[NickP]

Thanks guys. The current case is a 4R/5R and was original to the car (72 T). The heads were from a 906 (real deal) and my mechanic says that they can’t be used with 98mm pistons. I don’t known if they would work with 92’s, so I’m a bit limited.

Nux- I could bore the spigots, sure but I’d probably seek a stronger 7R case if I were to stay mag vs aluminum and go from there. 7R cases are fairly easy to find.

[Trackrash]

Here is a thought. Since you need a new crank, go with a Carrera or GT3 crank in that SC case. Bigger can be better.

[KTL]

With a bigger oil pump like the 930 pump, you'll want to install the 930 piston squirters in the case.