3.6 mods?

[rdane]

I have a 964 case, heads, P&Cs, rod, crank and ignition. All the motronic off 95 is there with the rest to get the engine up and running.

What would you do while putting the engine back together to maximise the relaibiltiy and power.


I want more power that the 964s originally put out. 270 at teh wheels seems easy for the '95. What needs to be done to bump the base 964 engine to '95 levels or better while maintaining reliability.

Engine is apart and being totally rebuilt so the only costs are parts, not labor.

[Wayne 962]

The problem with Motronic units like these is that you can't make any major changes without modifying the maps in the chip. You can try running a slightly hotter camshaft (there are a few, but I can't remember them off the top of my head). I wouldn't recommend bumping the compression on these, as I think they ran about 11:1 in 1995.

The best thing for the 3.6s would be to run hotter cams and modify the pistons to fit. But then you will run into problems with the stock Motronic (both programming and fuel reversion issues below 3000-4000 RPM). A good way to avoid this is to run a TEC-3 or to run PMOs. Eade is building his RSR replica with PMOs. I don't think he's swapping pistons or cams though (future project maybe). Note that doing all of this will cause problems with smog...

-Wayne

[Bill Verburg]

I am assuming that you have a '95 993 engine?
The casting on the case is 964*****

If so;
top end, 993ss cams or maybe even a tad hotter work great w/ stock Motronic, RS valves(52/43mm) Ti would be nice but not needed for a mild street engine, some tidying of the ports, stock 993 valve train is good to ~7800 so unless you want to twist it past there more exotic springs etc. aren't needed. Use US sourced Phosporus-Bronze guides.

Get a chip burned on a dyno.

Headers will depend on heat requirements, here are some really nice ones, 1.75" OD max unless going racing. If heat is needed B&B are ok.



Don't forget the bottom end, Arp or Raceware rodbolts

[rdane]

Sorry for the confusion and thanks for the help.

Engine case and the lower end is a 964 3.6 from 1992. The rest of the engine (induction, twin plugs ect) comes from a '95 that was stripped and went to electromotive and PMOs.

I was thinking ditch the early 3.6 crank was all it would take to have a '95 3.6 if everything else is the same spec. Are the rods the same on the 964s and the '95 993?

What I have now is a miss match of a mid year 964 3.6 and the induction and some of the parts from a '95 all in boxes. I was wondering if there is anything to change out or replace for better performance as we do the rebuild?

[Bill Verburg]

964 and 993 rods are not interchangeable.

You can put a whole 993 bottom end(crank, rods, p/c) into the 964 case. The 993 crank is much more desireable.

What heads?
If you have 993 then you need to decide whether to stay w/ hyd. lifters or switch to mech., for mostly street use I would keep the hyd. You will also want to backdate the cam drives to 964 parts.

For '92 964 heads just clean up the ports.

[Wayne 962]

Yup, you want to stay away from the 964 rods with the smaller rod bolts, or use ARP fasteners instead...

-Wayne

[Bill Verburg]

you want to stay away from the 964 rods with the smaller rod bolts

993 rods use the small bolts as well, the rods are stronger and h/d version as well as aftermarkets are availble but generally not needed for street use.

Do replace any of the small rod bolts on any engine w/ ARP or Raceware.

[Wayne 962]

Originally posted by Bill Verburg
993 rods use the small bolts as well, the rods are stronger and h/d version as well as aftermarkets are availble but generally not needed for street use.

Do replace any of the small rod bolts on any engine w/ ARP or Raceware.

Right - although the problem doesn't seem to show up as much on the 993s - not sure why...

-Wayne

[VincentVega]

Timely thread. I have a 94 3.6 w/ rs cams. Is ~7800 a safe redline for an otherwise stock motor?

[Wayne 962]

I'd say 6500 is a safe red line, and 7800 is too high...

Remember, this is a latent failure. An over-rev may not cause a failure of the rod bolts when it happens, but it may weaken them. Repeatedly revving the engine high will cause more damage each time. Then, repeated normal use of the engine may cause them to become loose and fall off or break. This is my theory on the subject, and one of the reaons why I like a little bit of red Loctite on rod bolts.

-Wayne

[Carrera3.5L]

Originally posted by Chris Martin
Timely thread. I have a 94 3.6 w/ rs cams. Is ~7800 a safe redline for an otherwise stock motor?

Chris, just out of curiousity, why would you rev the motor to 7,800 rpm? If it is basically stock with just RS cams, I seriously doubt that it is making power anywhere near that rpm.

Ralph

[Bill Verburg]

Timely thread. I have a 94 3.6 w/ rs cams. Is ~7800 a safe redline for an otherwise stock motor?

That is about the limit for a stock valve train, but the bottom end will pop well before that unless it is beefed up.

Not sure what RS cams you have RSA is the same as regular as are the Cup cams.

W/ those cams there is no reason to rev past the very low 6k range.

[VincentVega]

Thanks guys, I was thinking ~6k was about it, just making sure. The car has a 7.3:1, so 6k comes reall quick.

[JohnJL]

Don't forget the LWF

[Bill Verburg]

Don't forget the LWF

All 3.6 t/ps will use a light weight flywheel compared to stock 964/993