brwilson

My 2000 C2 3.4L engine is toast. Rod bearing failure damaged the crank and threw debris through entire engine which damaged the oil pump, scored the cylinders, and may have damaged the bearing carrier. Lots more new stuff needed needed as well...


A major cost will be the replacement cylinders, but apparently, I can increase the bore to 99 mm for no extra cost, and can go up to 101 mm with only a modified head gasket. Is this right?


I also have the option to go with a local shop that will install steel cylinders, or go with LN aluminum Nickies. The LN are slightly more expensive and will need a longer lead time.


I am already contemplating some of the other upgrades. Rod bolts? Maybe. Rods? Maybe not. Upgraded baffle/sump? Probably. IMS and Clutch, yet again? Of course.


Are there downsides to increasing the bore? The shop I am working with says almost no one replaces their cylinders without increasing the size, and there are no ill effects even using the standard ECU.

Macster

Flat6Innovations has come out 4 square against using steel cylinder liners.

Here's a link:

http://flat6innovations.com/index.ph...inder-sleeving

The 3.4l engine is felt by some -- J. Raby of Flat6Innovations being one as I recall -- to be a quite good engine. Part of the reason is the smaller cylinder bores with thicker cylinder walls.

If you are looking for as much of a bump in HP as you can get bigger is better -- there is no replacement for displacement -- but the trade off may be a shorter engine life.

I would think with 4.0l displacement one could read newspaper print through the cylinder walls. At night.

But check with the Flat6Innovations site to read what it has to say about going bigger at least using Nickies.

Here's a taste:

Nickies™ feature our superior aluminum alloy up to 66% stronger than than the cast in Lokasil™ bores or MMC sleeves, improved thermal conductivity (unlike steel sleeves), reduced wear and friction, and allow for larger bores without any loss of strength or longevity. In fact, Our NSC-plated, CNC billet, solid aluminum Nickies™come with a lifetime warranty on cylinder plating.

We have overcome the d-chunk and slipped-sleeve problems associated with Porsche 986 & 996 models by engineering an aluminum alloy that has both high ductility AND strength, allowing for larger bore sizes while still increasing reliability, addressing the well known issue of cracked bores in stock engines

If the cylinder bore is increased in size there's the question of can the stock intake and exhaust deal with the increased air/exhaust flow?

How is the stock 11:1 (or more) compression ratio maintained? Are the larger pistons that are fitted have more dome to keep the compression ratio the same? If so does this dome interfere with air flow into the chamber?

These engines are air pumps. As they come from the factory they are quite balanced and can flow a good amount of air. The intake, engine displacement, exhaust, and valve sizes, cam lift/timing all come together to make a pretty good package.

As an example: My 2002 Boxster 2.7l engine can rev and pull good up to its 7200 red line. That's a good sign the engine breathes pretty darn good.

I'd have to see some reliable dyno numbers for a big bore 996 engine to ensure the engine output is worth the cost.

After I posted the above I went back to the Flat6Innovations site to do some more reading.

Big bore kits, for instance taking a 3.4l to 3.6l are offered. Custom bore kits are available on request so I guess you could request a 4.0l bore kit, but well, let me paste this rather than type it in:

Having now done 300+ engines without a single failure, we're proud of our proven track record. The bore sizes we have chosen are conservative choices made to ensure continued success. We can make larger bore sizes special order for a nominal fee, but we require the customer to sign-off on and assume any and all liability.

brwilson

I was worried that increasing the bore would cause a cascade of required upgrades or risk destroying the engine. From what I am told, I probably wouldn't realize much improvement without modifications to both the intake and exhaust, but most of this could be added later as budget allows--I hope. I also understand that there are limitations in the porting of the heads, and on my year's engine it is on the exhaust side more so than the intake--this is more work I could consider. In either case, It would be nice to have an option for increased performance later, but honestly, my car had plenty of power for me as it was.

Mike Murphy

This will solve the displacement problem:

2006 C6 LS2 ENGINE 6.0 400HP 84K MILES

Ahsai

I rebuilt the engine myself from 3.6 stock to 3.8 LN nickies. I couldn't be happier with the extra torque and power and no CEL.

If I were you, I would consider 3.4 to 3.6 LN nickies with JE pistons package. Should get a nice boost.

Ahsai

Also check with Bypro. He builds engines.

https://rennlist.com/forums/996-forum/649044-3-6-rebuild.html

brwilson

That may be how I go. The LN is an option, but it probably takes 6-8 weeks just to get the case back. The local machine shop would install the steel cylinders (I don’t have all the specs, materials, but will find out) in about 3 weeks, but would only be about $400 less than the LNs. The engine builder says he has had no problems with the steel cylinders but that the LN-being a high-quality, well-marketed product, is usually a consideration for people when they consider resale.

I note that he won’t just put in sleeve liners—the whole cylinders are removed and new ones installed.

Coopduc

Just curious, LNE also offers a 3.4 to 3.8 conversion for the same price. Any reason why this option shouldn't be considered?

Coopduc

BTW, I'm in the same boat as the OP with my 3.4 although I haven't yet opened the engine to determine the extent of the damage. It has a serious death knock assumed to be a bad rod bearing. If the crank is damaged, there doesn't appear to be a repair available in terms of undersized bearings. Good used cranks are pricey/rare.
I'm just exploring options at this point. Actual work won't start for a few months.

Ahsai

Just email LN and talk to Charles. He will give you all the reco you need. Keep in mind the cylinder walls will be thinner as you increase the capacity so I think 3.6 will be nice. Also 3.8 may require new rods.

Do not go with the iron cylinders, especially if it's only $400 less! Nickies is superior.

Do you know Ferrari F355 engines use Nikasil cylinders and have super tight tolerance? Not to mention the Mezger engines...

lowpue

Sam e exact thing happened with my 3.4l. I explored all of the options listed but went with 997S 3.8 engine upgrade. Will post project when done.

Ahsai

That's a much more expensive proposition. You will need new DME, instrument cluster, engine harness, non return fuel system, etc. Lots of wiring work.

AWDGuy

Went from a 3.6 to 4.0 with LNE. Did the work myself. I used ARP hardware everywhere I could except the head bolts. I also got LNE billet hex drive for the oil pump, their thermostat and their billet IMS chain paddle. I also got my rod bearings from them.

lowpue

yep...exactly right.

AnthonyGS

Iron liners work great in LS based blocks. It's been done. I know people are working on it for the M96, but for $400 you go with the proven solution. That's going to be far less than 5% of your total outlay. You'll sleep better at night too after banging the loud pedal the day before.