Boost in extreme moderation

I want to start this post by saying my engine blew up on me. It blew up on me with no boost, just a stock 3.4 m96 and it shredded its guts in to a glittery oil soup. For that reason I did the swap to a 3.2 out of an 02 boxster. All of the fuel system and electronics from the 3.4 remain intact on the new engine, which raises the question in my mind why not shove 3.4 liters worth of air in there? 1 atmosphere is 14.7 psi, 3.2/3.4=0.941 14.7*0.06=0.882 so a 1 psi boost above atmospheric levels should shove the same amount of air in to the engine that the 3.4 was displacing theoretically increasing the power output to that of the 3.4. Theoretically because the engine still thinks it�s a 3.4 this minor amount of boost should run fine without going lean on the stock fuel system and ecu tune. my understanding of tuning is limited but as I understand it the ecu basically reads the intake and the o2 sensor and determines everything based on that, would adding a small amount of boost be kosher and within the ability of the ecu to figure out on its own? What would the outer limit of that be if so, maybe 2-3 psi? wondering if I can get my 3.4 power back (or slightly more) by rigging up a super low boost turbo (sub 3 psi) on a no tune ecu and stock fuel system? Basically a very �minimal effort� slap it on and don�t tune setup. Tell me why this is a good or awful (or both) idea please

You would be better off with a supercharger. The factory tune in NA engines tends to be very lean in the part throttle area. Most boosted tunes need to up the fueling in that area or it ends up very lean indeed. If you can fix that mild boost could work. Do remember the M96 has a high compression ratio which won't like much boost without a lot of fuel, or E85, or really high octane.

Could list all the potential problem$ you'll have to overcome with boo$ted power adder$ on a m96, but if you're contemplating an M96 diy turbo kit,,, you can probably figure that out for your$elf.... JMHO,,, Be happy with what you accomplished, you did very good. Very few spend that little to get back on the road again. Be happy with your reduced power, you don't really need' more. Car will probably still go 150mph.

Adding boost to increase the amount of air rather than adding displacement will increase the compression ratio. In the cylinder. You need to address the effects of the increased compression ration to avoid detonation which will destroy your engine. If I was going to add boost I would be sure to use good hi octane fuel and log some data and get a custom tune to be sure the fueling was adjusted to prevent detonation. Generally, the first casualty of detonation is the rod bearings, then the ring lands. Mark

The best bang-for-the-buck solution for boosted power that I can see is a VF supercharger with water/methanol injection. A custom turbocharger setup is possible, but invites a lot of complexity that I don�t think is worth the effort. It may also end up being more expensive than the supercharger when all is said and done.

The beauty of modern engines is the introduction of Computer Controlled Electronic Fuel Injection and Wide Band 02 Sensors for Engine Tuning.....Engine Tuning is important for all engine but is of the utmost importance when it comes to SuperPower Adders like Turbo's , Nitrous Oxide , or Superchargers to avoid self destruction... A lot people have said that the M96 is not robust enough to handle PowerAdders , but the real evidence is just not there...All catastrophic weaknesses on the M96 have been identified such as oil starvation in high g-turns, IMS, cylinder cracks due to thermal expansion uneveness ..and all have upgraded parts to cure those issues.... I have seen 850hp M96 engines decades ago but there is just no business model for such an engine or is there many people pushing that envelope...I have seen uddles and uddles of tried-and-true Ford and Chevy v8's split in half due to Power Adders ....but the M96 engines I've seen that had holes in the case/block were due to thermal runaway from lack of lubrication ...If you inspect them closely you will see a "bluing" of the rod journal/crankshaft that is caused by oil starvation, then a failed rod bearing, then a failed rod punching a hole in the case.... I was involved in SuperPower Adders ( Super Chargers, TurboChargers, Nitrous Oxide ) back in the 70's before EFI and WideBand 02 Sensors were invented. Back then you diagnose issues by failure analysis, a hole burnt though the top of the piston meant a Lean fueling under full power...a bent or broken part meant the need for better/thicker/stronger material/design, A "blued" part meant a lubrication issue.... You need to control the Ignition Timing and Fuel Enrichment, and this is much easier to do with EFI and WideBand 02 Sensors......The DME on the M96 can control Ignition Timing to retard if Knock is heard, but the fueling can control in "closed loop only" during cruise......under full throttle the DME goes into "open loop" and uses a set Fuel Map with condition modifiers that does NOT use 02 Sensor feedback to control Fueling, so as others have stated the compression ratio will be increased...and will probably need extra Fueling to cool the combustion chamber ...A few PSI of boost is obviously not significant, but can be enough to go "over the edge" which can be done on any engine... One real Caution I have seen so many times:::: it is very very easy to get "greedy" with SuperPower and that always ends in catastrophe !!!! ... So the decision is actually all yours if you want to learn to Tune properly and add the complexity of a little SuperPower , Or you want to take a gamble with your $4k dollar engine as an experiment to see if it will be OK as-is with No Tuning and a little SuperPower ....Or just enjoy it like it is with a little less Power... BTW :congrats on getting back on the road for $4k and some labor....I have recommended the 3.2 Engine many times on here for people in a money bind who just want to get back on the road !!!....The price will probably go up when the masses learn the 3.2 is only 200cc less and with just a few holes drilled and tapped with fit nicely into the 911 ....

Quotes source post: 19939961

In doing a bit of research I found that the compression ratio of the 3.2 is actually only 11.0:1 whereas the 3.4 ratio is 11.3:1. This 3% difference is what I would bank on in a no tune setup, if I take 103% of atmospheric pressure so a boost pressure of .441 psi, it would actually not exceed the stock compression ratio of the 3.4. If the boost pressure is pushed to 1psi even that bumps the compression ratio to 11.8:1 which according to some Honda forums is under the top end of what�s safely manageable for 91 octane fuel (what I�ve been running on). Additionally for perspective a naturally aspirated Ferrari 458 has a compression ratio of 12.5:1 which is well above what I�m shooting for and runs on regular pump gas. According to a basic boost calculator if my engine is making 275hp now that 1psi should add 15-20 hp putting me right back at stock 3.4 hp levels (295hp) the thinking here is to create a feasible step between not boosting at all and boosting the **** out of it which a lot of people seem to skip or ignore entirely, the goal would be to restore stock power levels on the lowest diy budget possible (I know, not very por shah of me) this option might legitimately be less than half the price of even a used up eBay 3.4 or a proper rebuild. Am I missing something with this compression ratio stuff or is this as �safe� and practical as I think it is?

You should have pulled the cylinder heads off your engine before installing it into your car. You can lower the compression ratio by double-stacking head gaskets, which would have allowed you to run more boost and ultimately make more power than the 3.4.