Engine Rebuild - Displacement Options

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.

Quotes source post: 14601817

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.

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.

This will solve the displacement problem: 2006 C6 LS2 ENGINE 6.0 400HP 84K MILES

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.

Also check with Bypro. He builds engines. https://rennlist.com/forums/996-forum/649044-3-6-rebuild.html

Quotes source post: 14602305

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.

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?

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.

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...

Quotes source post: 14601817

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.

Quotes source post: 14602672

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.

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.

Quotes source post: 14602690

yep...exactly right.

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.

The total cost for the rebuild including LN Nickies, ARP bolts, new oil pumps, bearing cage and various other stuff (upgraded baffle, new oil filler neck, new battery cable, etc.) is just over $18,500, regardless of the bore I choose. It is basically about $8500 in labor and $10,000 in parts, so even if I did it myself, and spent the next 6 months purchasing and fabricating tools and taking up my limited garage and driveway, it would probably still cost $13K. This is my guess.

What parts do you feel you need to fabricate? The cam timing, wrist pin insertion tool, and engine stand yoke can all be purchased. This is the bulk of the special tools required.

I haven't researched it too much, but I do know about the cam timing, wrist-pin and I think there are some special chain tensioner tools. I would need to buy an engine stand and a couple of jacks--one high enough lift the car and drop the engine. Also IMS and RMS tools. I can certainly take things apart and put things back together, but I am a little wary of the tolerances in fitting things like the rings, aligning the case and the carrier cage, etc. I am also worried that if I rebuild it myself, rather than a reputable builder, I won't be able to sell the car, regardless of the care I took. It's still a Porsche, and branding is important.

Here is a link to what a 3.4->3.8 LN looks like post processing. Sorry I'm unable to post images directly for some reason: https://photos.app.goo.gl/fszKxtvRwL0jR3G03 I'll let you know how it turns out. 3.4>3.6 as Ahsai points out is almost a no brainer as pricing is very similar with LN, it was not much more to go to 3.8 in my case. I ended up needing rods as someone number stamped my end caps so needed replacement anyhow and by the time you mess about buying std rods, new bearings and ARP bolts etc difference was minimal. LN did a deal on forged rods too (I found them cheaper somewhere else and LN got pretty close). Its not a cheap process, but anyone in the P car community actually values this v's cast sleeves. I feel your pain, hoping its all worthwhile.

Maybe this has been proven insignificant, but increasing the bore will change your compression ratio. As I stated, maybe this does not make a difference, but numbers used for the combustion chamber and piston crown volume in the rebuild threads did not match what I measured. And using what I measured, calculating the CR with larger bores changes the value from the factory spec a lot.

Quotes source post: 14604687

No it won't if you use the LN nickies + pistons package. They've done all the calculation and custom made the pistons for you to maintain the same or similar CR.

You can do it once using proven components, or you can do it twice if you like cutting corners. Our phone lines are clogged these days with people who have made poor decisions, used sub- standard processes,and now are facing a problem they can't solve. Yesterday, Jud was out sick, so I actually had to waste time in the office. The phone rings and I answer it "hello, I bought an M96 engine from one of your competitors with iron cylinders, and I need help" My reply was "sorry, there's no help for you". I didn't answer the phone the rest of the day. Just let it ring. I have zero patience for those calls. OP: Choose wisely, you'll get exactly what you pay for.

Hi loudt2 Put the 'Big Pack' from Do88 into my Turbo and can say it is first class. Makes an awesome difference with torque and hp. Also put in Fabspeed headers, GMG turbo back exhaust, BMC air filter, pinned with Sharkwerks coolant elbows, plus whilst the engine was out, replaced the waterpump, plugs and serpentine belt. Very happy with the resulting performance! Clutch was fairly new on mine when I got it, otherwise I would have put in a lightened mass flywheel and better clutch. Happy building

Displacement options? I didn�t rebuild but replaced with 3.2 and all seems well! Haha. It�s not for everyone but it�s a heckuva lot cheaper than $18,500. I still do want something more powerful in the future but I�m not in a hurry.

OP: Overall, I’d ask what you want to do with car, street only, some track, lots of track? FWIW after previous comments (LS?), at 106K miles I replaced as many problems I could for a street/some track (no slicks!) car: - LNE 3.8 cases (yes, took a long time but nothing else compares) and pistons, +$500 or so. - ARP everywhere, esp. on rods - stock rods, wished I’d gone with Carillo - pinned IRS gear to IMS - new chains, upgraded paddles, retained solenoids - FS6 “Solution” IMS bearing (original showed no wear!) - new low temp thermostat, oil pump, water pump, etc. - newish clutch retained - heads machined by Hoffman with new seals (important!), etc. but not flowed Lots of other stuff I can’t remember. Cost was right around $20K from local Indy with 25+ years building racing engines.

Thread started 4 years ago......

Getting some good conversation going 😊

As more 996s age, rebuild now that more is known, is indeed a relevant topic. While I find my 3.4 adequate it seems silly not to increase displacement at rebuild. While the thread is four years old significant change has occured. The ideal displacement recipe in full detail, might be different now. Supply chain issues have impacted on M96 engines, at least in Australia. The role of supports after investing in displacement such as UAOS, and sump solutions/dry sump solutions, could be clearer. Headwork could be better defined. Also the role of tuning these older ecus. Or is it time to be like the JDM world for standalone management that can be spliced in with factory looms to develop.