Can 10.5 Euro pistons pass Calif smog test
 

I am rebuilding a '88 3.2 and would like to know if anyone has used the 10.5 compression Euro piston and cylinders from Pelican and passed the Calif smog test?

Euro pistons are 10.3 rated. Actual compression ratio is less (about 9.8). I have not tried to get one smoged, but it should make no difference. The smog amount depends on ignition timing, mixture, and condition of the cat. Compression shouldn't matter.

-Andy

My opinion (everyone has one...LOL)...compression ratio can have an effect on smog.
The better the engine is (in state of tune) the lower the junk coming out of the tailpipes.
In a perfect world...the engine would be at 100% efficiency...and no emissions at all.
In reality...the misfires and mis-adjusted fuel systems all add up to smog out the pipe.
This is one reason to have the engine at running temps before you let the DMV at it.
I passed my old Ford 427 through the smog lane several times...and the techs there could not believe how low the emissions were...but getting almost 675HP out of the beast used up all the fuel...mind you...if they checked it at the track...with both carbs wide open...I suspect it would have been a failure right away..LOL.
Old saying...there is nothing more efficient as a great running hot rod!
Bob

Assuming in good condition, it would pass the tailpipe portion with bigger cams and no cat.....

An increased CR will increase the NOx but probably not enough to put you outside the limits.

Thanks for the opinions I'll let everyone know how it turns out. I'm going with the euros. If it doesn't pass I'll move. Thinking about that anyway.

Move to Texas. No smog test on cars 25 years or older.

My 78 just became smog exempt in New Mexico (35 years old is the limit).
Now, if I could just get that engine rebuilt faster...

Unless you want to run 100 octane, you will experience detonation with even moderate use.

Maybe our fuel is better at the pump up here, but we don't see detonation on ROW cars that have been imported here.

Cheers

being in the design phase of my 3.4, I am sure hoping that a twin plug Mahle Euro piston/cylinder set as described by the OP will work. I mean the Carrera 3.2 gets to 10.3 compression with single ignition doesn't it?

Emmissions wise I was going to fit catastrophic perverters on a modified SSI exhaust, hope the extra NOx is OK, I just need to find the smallest and flattest catalytics there are...

Dennis

Jeff,
While you know a ton more about air cooled engines than I ever will what I can tell you is that since Colorado converted to CA smog standards stock 911SCs with cat pipe removals are failing.

Even my Subaru, which used to pass easily with a very high quality metal hfc on it now requires me to reinstall the factory double cats every two years to pass.

Now on the engine in question it may just require a retune and cat installation every coupe of years to smog, but I have some skepticism that it will pass without some effort. And that ignores the visual. Before I mOved out of CA they were getting more aggressive on visual and track pipe cat replacements would easily fail many cars.

I have a good friend with Euro pistons in his SC and cannot run the car with pump fuel. Too many around here exhibit broken top rings.


California has a very comprehensive database for all vehicles that go through the smog check. They have taken an average of the actual emissions recorded and lowered the allowable emission levels of the SC to where you cannot pass without the Cat on the Vehicle.

Ca

There is no reason for this. Our PRC/PCA Spec911 cars run with Euro pistons ("blueprinted" to 9.8) on 91 octane pump gas. With a normal Euro having about 9.3 compression you should never have a problem. These cars have been racing for 10 years now with up to 21 cars per race. We've had 3 piston failures that I know of. We run 29 degrees of advance. Engine failures (except over-revs) are very rare in our class.

-Andy

I don't think I could compare Spec911 experiences with daily driver usage as I cannot imagine that you spend most of your time below peak torque.

Our real world experience is Low RPM associated with higher engine loads combined with Euro pistons can result in damage. You simply do not have a reasonable margin of safety with environmental variables.

Intersting info, we have "aircare" up here for smog tests. They too have a pretty good database, sourced from all over NA not just locally. Like I said, we have run euro motors, with 964 cams performance chip and ssi's through without issue. These same motors do not detonate on 92 octane at the track.

Remember the advertised 10.3 CR is wildly optomistic. I think the staff at Mahle that measures CR had troubles in high school math... :) At true 10.3 single plug motor will detonate like mad on pump gas.

Cheers

I thought I read somewhere that the Mahle CR is calculated based on zero deck height... is that correct?

FWIW, I put Euros 3.2 P's and C's on my new rebuild. We have 94 octane freely available in Toronto (Petro Canada), but it has Ethanol. The choice I prefer is the Shell V-Power, which in Ontario is Ethanol-free but 91/92 octane. For my motor's start up, I used the Shell fuel.

I discussed this with a reputable local builder (who also did all the machine work for my rebuild) and he suggested I use 0.5 mm thick cylinder base gasket. He had done that many times in the past and had no trouble with Euros on our 91/92 gas and consdered the thicker base gaskets a bit of "safety margin".

When I calculated the theoretical difference in CR from the extra 0.25 mm of base gasket, it lowers from the specfied 10.3 to 10.0, which is half-way back to U.S. spec CR. Of course, the true CR is almost certainly much less - it just amazed me how much of a difference a quarter millimeter made...

The motor displays no signs of detonation on the Shell fuel.

I have heard that California is a tough place for quality fuel.

I'm agreeing with Aaron on this.

That's exactly where my Safeguard triggers on my 930; opening the throttle from low RPM climbing hills - pulls a few degrees of timing out around 2800, vacuum gauge shows a pretty good load but nowhere near boost. This hill is right after a red light on my commute; drivers slug away from the lights and after 2, 300 yards or so, suddenly have to use more throttle to stay with traffic, Safeguard triggers and pulls timing.

See it just about every time. To the point I'll check the gauge connection if I don't...

In fact, tiny detonation tell-tales on a couple of cylinders on a top-end reseal was why I fitted the Safeguard in the first place.

The smog change was a big surprise to owners as there was no warning....they just failed them. They were scrambling to put all their stock exhaust back on to pass.


It could be good old SoCal fuel that we are blessed with that has caused the passed failures. :)