2.5 shor stroke engine, my plans Options

[michel richard]

So here's what I'm doing for the engine as part of my "GT style" conversion. First and foremost, I figure that an engine in a GT style car has to be rev-happy.

So, here's what I'm putting together, with the help of my trusty wrench, Ron Green of Campbell Gararge in Montreal:

Short stoke 2.5 Porsche engine:

1) Used 7R engine case, align bored, Timeserted, shuffle pinned
2) 90 mm JE pistons, 10.5 compression ratio
3) 90 mm replated Nickasil cylinders, sourced from EBS
4) Standard piston ring set
5) 66 mm counterweighted crankshaft
6) GE 80 camshafts
7) EBS racing valve springs
8) EBS valve spring retainer set for above
9) 2.0 connecting rods
10) ARP rod bolts and nuts for above
11) twin plugged heads
12) Electromotive HPV twin ignition
13) Turbo lower valve covers
14) front mounted ol cooler with "GT Style" installation
15) new bearings and gaskets all around
16) miscelaneous engine parts, stock.

I still need to figure out what to do with the port sizes in the head. The target is to have a 8,000 rpm redline, and 250 hp, although the redline is more important than the hp to me.

So that's the plan. I pulled the trigger on the hard parts above today. ( I already have the crank and the miscelaneous parts).

Induction is going to be 40 mm PMO carbs, jetting to be determined.

I'll post to this thread as progress is mad on the engine.

Michel Richard

[michel richard]

OK,

Thanks for the collective wisdom. I'll comment and react to the various input:

First, generally, I'm a big believer in the fact that good enough is often just that: good enough. And in keeping a firm eye on the target.

Once again, I'm building a "sport" engine, one that I hope will be fun and exciting on the street, and be track-able once in a while.

So:
1) on the mag case and 8,000 rpm. I've taken my 2.2E built on a 5R case to 7,500 several times, without any problems. I'm pretty sure that the 7R case and upgraded valvetrain will safely take me to 8,000. Not for extended periods, and admitedly at a certain cost in engine longevity, but I doubt 8,000 will blow the engine. Sure, an aluminum case would be better, but they're hard to come by. They're non-existent, that I know of, in Montreal.

2) On the induction. In view of the number of comments above, I will certainly investigate. I think it's probably a good idea to at least start the engine with some carbs, because it's easy to do so. I would probably go to some sort of injection if I need to move away from the PMO 40s. The problem with fuel injection systems is that they sound good on paper and in theory, but they're a lot harder to get support for and lot harder set up. I agree that once dialed-in they'd be much easier to run.
I'll certainly talk to PMO to see what they think. And once again, I'm not looking for an engine that is at its most efficient at 8K, only an engine that is able to run and sound exciting when up in the upper reaches of the rev range.

3)on the 2.0 rods: Carillo and Pauter rods are approximately 5 times the price. And the 2.0 rods will work.

4) The heads are from my stock 2.2 E. We'll keep the valves (they've got less than 5,000 miles. Spoke to my mechanic last night, and his suggestion is 37/35 (IIRC) for a streetable engine. He says he would recommend another couple of millimeters if i was going for a screamer of an engine. That is one area where my mind really is not made up.

5) Mark, are you saying that a /6 SDS system that would do both injection and ignition would be under C$ 2K ? I have'nt bought the Electromotive system yet, so it's not too late.

Thank you all for your input.

Michel