displacement increase - newbie question

[kapple]

So I have a stock 78SC engine and it has 105632 miles on it.

I’ve been reading ahead a little in Wayne’s book where he discusses Alusil vs. Nikasil cylinders. Say by chance it ends up that I have the Alusil cylinders so l will not able to re-use them without gambling.

I could take this as an opportunity to increase my displacement from 3.0L to say 3.6L by using the 100mm 3.6L Nickies cylinders & JE 3.6L 100mm 12.5:1 pistons.

I imagine that as a consequence I’d have to change the crank, rods, the profile of my cams, twin plug the engine, use better head studs, and get the heads modified for the increased displacement.

I guess my questions would be...

1. Is this possible?
2. What am I missing?
3. Could my 915 tranny handle this?

I realize that I’m using CIS and I plan to do one of the aftermarket CIS to EFI kits but I don’t want to break in the engine with a different fuel injection.

[88-diamondblue]

1 Anything is possible with enough money

2 I don't think at 12.5:1 compression that the engine will last long, if intended for racing and being rebuilt frequently you might get away with it. 10.5:1 and twin plug is what I see as being about the max for a street motor. Since your looking at Nickies give Charles a call at LN Enginering. He posts here as CNavarro

3. The 915 should handle it.

Another option given the amount of money you will spend to rebuild is transplanting a 3.6 from a 993. Talk with Charles at www.lnengineering.com, Henry from www.Supertecperformance.com or SteveW at www.Rennsportsystems.com about the options available and what will last for what you want to do with the car. The project sounds like a great deal of fun.

[kenikh]

I'd only recommend using the stock 12.5:1 pistons if you are using a stock DME with knock sensor. Otherwise, you'll end up with eventual detonation related failure. 10.5:1 with twin plugs max on carbs, etc.

[kapple]

Originally Posted by 88-diamondblue

1 Anything is possible with enough money

2 I don't think at 12.5:1 compression that the engine will last long, if intended for racing and being rebuilt frequently you might get away with it. 10.5:1 and twin plug is what I see as being about the max for a street motor. Since your looking at Nickies give Charles a call at LN Enginering. He posts here as CNavarro

3. The 915 should handle it.

Another option given the amount of money you will spend to rebuild is transplanting a 3.6 from a 993. Talk with Charles at www.lnengineering.com, Henry from www.Supertecperformance.com or SteveW at www.Rennsportsystems.com about the options available and what will last for what you want to do with the car. The project sounds like a great deal of fun.

Thanks for the info!

The car will be for street use so reliability is of concern so I’ll forget about the 12.5:1 compression and drop it down to 10.5:1.

I had considered dropping in a 3.6 from a 993 but then I’d have an engine with a good amount of mileage on it already and possibly some other problems. I’d would much rather spend roughly the same amount of money and have a freshly built engine and not have to wonder how long down the road the 993 engine would get me.

[kapple]

Originally Posted by kenikh

I'd only recommend using the stock 12.5:1 pistons if you are using a stock DME with knock sensor. Otherwise, you'll end up with eventual detonation related failure. 10.5:1 with twin plugs max on carbs, etc.

Since it’s a street car wouldn’t it be better if I converted the CIS to EFI then running carbs?

[cnavarro]

You have quite a few options:

1) Take your 95mm alusil cylinders and nikasil plate them, then match to JE Pistons;
2) Get a set of used 3.2 Carrera cylinders, bore out, and nikasil plate at 98mm, with JE Pistons;
3) Machine the cylinder tops of your alusil cylinders so rather than having a groove, it would be a ledge. Then you can bore out to 98mm and nikasil, fit with JEs, then have an annealed copper sealing ring made up to fit in the groove with .001-.003" crush. I've done this a few times to make sure of all those alusil cylinders floating around that can be had for cheap.
4) Go new - you have choices from inexpense to expensive, including QSC, Perfect Bore, Mahle, JB Racing, and LN Engineering Nickies.

In response to wanting to do a 100mm bore, you can bore the case to a 105mm register and fit a 100/105 cylinder - that will take a 3.0 to 3.3 or a 3.2 to 3.5, and are sold new from many manufacturers, including myself (you can buy Nickies from Pelican too!).

Also, Andial used to sell a 3.0 to 3.5 or 3.2 to 3.7 102mm kit. I've revived such a kit, but offer it with a thinner machine in spigot to allow for better sealing at the case, with no loss of integrity of the cylinder, due to the material we use.

Your trans should be able to handle the extra HP and torque, as long as it's in good shape.

I would stick to 9.5:1 if you are going to keep the engine single plugged as well.

Also, you can have your fuel head modified or put on an enrichment device to help with the added displacement. Supertec, Imagine Auto, and a few other shops can modify the fuel head for the increased displacement. Andial should sell the enrichment device.