HunterSmokes

So I read around quite a bit and didn't find an answer to my specific question.

Most of the info I find is from people trying to boost CR to some high level and the answers are typically a "you should be fine with proper fuel/engine management".

What would be the highest functional CR on pump gas (no detonation or barely noticeable) if my engine was- P29 pistons installed in a D16Y8 with a totally stock everything else running on pump gas (to pass SMOG) and a modified head gasket thickness?

I would need this system running solid for emission testing but I also have plenty of extras to play with afterwards (it would be nice to not have to swap head gaskets later). A CR that allows for stock operation but still benefits from cam, timing, fuel management and exhaust later would be ideal. All running on pump gas.

From what I see, I can get a cometic head gasket thickness of .098 giving a calculated CR value of about 10.7:1. That is still better than stock but if I can go higher without issue running stock cams etc I would like to so I can benefit more from future upgrades.

I've read around a lot and still haven't really seen this answer. There are tons of videos, posts etc on P29 in D16 but not really specific enough.

You guys seem pretty experienced and that's really only the kind of answer that makes sense so I'm bringing it here.

Thanks!

NotARaCist

iTrader: (1)

Do you want the short no, or the long no?

tony_2018

You're not gonna get anywhere with a high compression NA d16y8. What are your power goals?

Or are you simply wanting to know what kind of power you'll get from an untune high compression engine?

HunterSmokes

I already have a set of the domed JDM pistons and want to get my old car running again with a bit of an upgrade (for occasional street use). It never actually ran with these pistons but they are installed (it's been years).

I would have to buy other pistons/rods, rings etc if what I have won't work so I'm trying to see if I can get what I want from the parts I have.

I basically just want to know if I can have P29 pistons in a more or less stock engine (no timing or obvious modifications) and still run on pump gas effectively enough to pass emissions/inspection testing. A borderline CR would be ok since I have aftermarket parts that would make it run properly afterwards.

Otherwise I'd have to get other parts but would probably want to swap out later anyways. It would be perfect if I could use what I had and just basically change a head gasket instead of replacing pistons. Knowing which thickness of gasket (or the general max CR at 91 octane with no other management) would help to decide if I need to find the extra parts and replace the pistons, rods, rings, bearings etc with something more stock, or not.

Not looking for anything special. I have other cars to drive. This has been sitting in my gar for a while and I want to play with it. Only real power goal is a general performance increase and something a little more fun. Not currently into racing or anything like that. Just for fun basically but want to use what I have if I can. Some day I might take it out on track but I would plan to drive it there.

HunterSmokes

Long no of course.

Any info is appreciated.

tony_2018

Someone tried to attempt this, unfortunately we never heard from him again. I believe he went over to D-series and ask the same question and obviously didn't even bother to update on whether he got what he wanted while still trying to past inspection.

Meaning running the stock ecu with a custom engine and didn't report back to let anyone know if he got it running or not and how. Some people are like that, they think we're shooting them down but its just we don't see any gains in what he wants to accomplish. Just trying to save someone the hassle of wasting dollars but hey its all good that he wanted to give it a try.

edit: I did a google search for "10.7:1 d16y8" and got a couple hits. Should try it.

NotARaCist

iTrader: (1)

You want to run noticeably (more than a whole point) increased compression on pump gas, without a tune. That's not how things work. Since you haven't told us the chassis, I'm going to assume it's in the car it came in originally, which means a 96-00. That means OBD2. To properly run compression that off from norm, you'll need to re-tune the ECU, which necessitates switching to OBD1, or a standalone, neither of which will pass smog. In short, no, what you want to do cannot be legally done, given the laws the state of California expects you to follow when modifying your car.

HunterSmokes

So I've read various different opinions on this and other forums about this.
General thought seems to be a big No but I am certainly more curious about what it might take to do it without significant mods.

At this point, going to stock or any other pistons would be only slightly more expensive if I had to make the change after I experimented with the p29 setup. I already have most everything I need and I want to play with it a bit to see what happens.

I think I'm going to continue down this path and try a few things to see what happens. I believe there's still a race gas company near my house and I've always wondered if octane booster would help if the engine REALLY needed it.
After that I'll go little by little to see how little I can do to the engine while still running that CR.

I also see a cometic head gasket that's 0.140 thick which brings the cr back down to 9.68:1 which might be worth a try as well.

If all of that fails I can just get new gaskets and a different piston/rod set set. It won't really cost me much more than doing it now and I mainly want to play with this for fun. I'm usually ok spending a bit more $$$ for educational purposes anyways.

It will take me a while to get this done and I may end up with other found issues after I pull this all apart.

I can post my findings here when I figure out what's what.

Thanks for the info.