CR and Octane needed in carbed 2056 rebuild, stock cam, Advice on octane for my 2056 Options

[Gatornapper]

Sorry for starting a new thread on this, but would like to know compression ratio on my 2056 rebuild with AA Performance heads, pistons & cylinders and about running 87 octane.

So far I know this:

Sir Andy said original 2.0 CR was 7.6:1. (http://www.914world.com/bbs2/index.php?s=&showtopic=73897&view=findpost&p=1780968 ) AA Performance said their 2056 package adds .2 to the CR, making it 7.8:1. This means my engine should be fine with 87 octane. Not wanting to split the case on a 60k mile original engine that had no need, I opted for leaving the original cam in vs. one for the carbs. Seems to be doing great with my new dual IDF 40 clones by EMPI.

I know Jake Raby says run what your engine likes as long as it doesn't ping/knock. That's a common thought shared by many.

Here's where I am right now: I cannot imagine the engine running better and I've used nothing but 93 octane since my rebuild to be safe. I'm running 30 deg. max advance using a new 123ignition dizzy. If pinging occurs at 30 advance, and 27 eliminates it, I have no problem doing that.

Power/torque in all ranges is far beyond my expectations. Carbs are dialed in as close as I can imagine - great drivability, great accel/response, great starts hot or cold, great idle, and 25 mpg on mostly highway driving.

But even with discount from Sam's/Costco, 93 octane cost is outrageous. I'd sure love to run regular but don't want to damage my sweet new engine trying it.

Problem with my listening for ping/pre-detonation is this: I'm pretty deaf. 79 years of guns, heavy machinery & motorcycles. Hearing aids help, but I'd have to rely on my sons to hear anything.

Love to hear from those with the 2056 kit from AA Performance. And others too.

GN

[Freezin 914]

I really can’t say much on this other than, I would be concerned if you have any ethanol in the gas. Up by us, 87 has up to 10% ethanol. The 91 around here as no ethanol. I run the 91 in my 14 and my 11, and all lawn equipment, I prefer to run real gas. Seems to have less issues deteriorating gaskets, rubber lines, etc. Just my .02
Hopefully some others will chime in soon.

[emerygt350]

I have been thinking about this as well and just keep sucking it up and putting in the 93. I am closer to 8.6 or so on the CR though. You didn't play with the shims? I will probably keep with that 93, I just don't put that many miles on it to really feel the pinch. My commute is barely a mile. Non-ethanol is around but it is more than the 93, and I tuned my engine to the 93 anyway.

[914Sixer]

Pure gas IF you can find it. Only running 8:1

[Gatornapper]

Wawa 5 miles from me has non-ethanol. As does another major source I use for my old Triumph motorcycles that is 20 miles away - 93 octane non-ethanol.

Price is about the same as 93 octane. Think it is 89.

Not sure why I need non-ethanol when carbs are new, stainless fuel lines new......and non-ethanol is unrelated to octane......

GN

Pure gas IF you can find it. Only running 8:1

[technicalninja]

Stoic (Lamda) for gasoline is 14.7
Stoic (Lamda) for e/85 is 9.0

E/85 is the equivalent of 105 octane
E/100 is 110...
E/100 requires oil be mixed in (like a two stroke) for long term uses.

Adding ethanol to Gasoline INCREASES resistance to detonation!
Alcohol INCREASES octane!

You HAVE to account for it in fueling.
Your modern car (flex fuel capable) does this seamlessly via WB02 and FI that is self-adjusting. Even then, they also have an accurate alcohol percentage "sensor" mounted in the fuel supply (often in the return hose). I steal these to install them on modded cars.
Have short- and long-term fuel trims? You're MODERN!

Fueling needs to change (get richer) and timing usually gets more aggressive as alcohol percentages go up.
Power is always UP, sometimes a significant amount.
Fuel economy DROPS!

All this stuff doesn't really help NA engines. I wouldn't run flex without BOOST!

If the equipment is all E/15 rated, clean, and the fuel is never more than 90 days old a small amount of alcohol will do nothing but keep stuff CLEAN!

Let it sit a year and you might have trouble.
Put it in an already nasty gas tank, the alcohol will LOOSEN all the trash in the tank, and I believe THIS is why so many folks say "gasoline only".

Almost all gas tanks have gone plastic. I didn't agree with that initially when I saw my first few.
Over 25+ years I've NEVER had to replace one for "corrosion"...
They stay MUCH cleaner!

Alcohol is more solvent than fuel or lubricant in my book.
I use it as the final "flush" in all of my AC work...

I DO suggest gasoline only on cars that will sit long term.
Normally it is 100LL from the airport.
One car I service has 10+ year old gas in it.

Aviation quality fuel seems to last forever...

[Superhawk996]

But even with discount from Sam's/Costco, 93 octane cost is outrageous. I'd sure love to run regular but don't want to damage my sweet new engine trying it.

Allow me to put in my ass clown persona for your entertainment. Some say this is really just my personality all the time.

This is a silly conversation. If you can’t afford to drive on 93 - sell the car.

5,000 miles per year / 25 mpg = 200 gallons used in your 914 a year.

Let’s say 87 is $4/gallon and 93 is $6/gallon

Are you telling me you can’t afford $400 / year delta in cost between 87 & 93 to avoid damaging your engine? Especially if you recognize that you won’t be able to hear the detonation yourself?


The reality is ethanol is an octane booster. However that ethanol boost is already factored into the rating on the pump. I’ll leave all the other ethanol pro vs con alone.

Likewise I’ll set aside the discussion of what your car really needs.

[technicalninja]

(IMG:style_emoticons/default/agree.gif)

Without all the modern sensors and technology I would buy the highest-octane fuel I could find for the car. As this is a "play" car I'd prefer 100% gas.
On a 914 that I was expecting to run 5k a year on I would go 100LL which I believe I can buy today for $5 a gallon.
I currently am repairing a Dodge truck that has an auto-dispensing 100-gallon tank of the stuff in the bed.
It's full right now! (IMG:style_emoticons/default/devil.gif)

I'm a $1 CHEAPER than Superhawk996!

And it might last 20 years...

The annual fuel cost of my "Fun" cars is never a factor I'm concerned with.

Now, if decent fuel was un-available "highest octane" E15 would be my next choice.

30psi would be E/85 or true race fuel (VIP, others)

Superhawk's delta is fierce!
Difference between 87-93 is something like .50 here.
I'd guess Virginia is closer to Texas than California prices.
The annual difference for Texas is $100...

[ChrisFoley]

To me, 89 octane at up to 8.2:1 compr. seems workable for a stock cam.
My experience with 87 octane is that a stock engine will ping on mild hillclimbing at highway speeds. YMMV

[VaccaRabite]

On my 2056 with a torquie cam and mild compression bump (8.6:1) I was able to run 87 and flog the crap out of the motor without it pinging. This was using Microsquirt EFI not carbs or stock injection.

Start with 87. Drive the car and see what it does. If it pings (it probably won’t) go to 89 (you won’t need to).

Zach

[Gatornapper]

While I consider myself wealthy as my wife is worth $10mil, and 8 kids worth several mil each, and I do have an unusual collection of old Porsches, $400/year is indeed a lot to me.

All my other Porsches and wife's car use 93 octane and we live out in the country - it's 5 miles to get anything. And I drive all my Porsches a lot - that's what they are made for. So our gas bill is huge at today's costs.

And I live on a fixed income from investments, and most of our net worth is in inedible, non-liquid real estate.

I know - too much personal stuff but we need to cut our fuel costs. Shouldn't have to explain. Not a silly conversation for us.

I'll try 87 a bit and have sons with good hearing help me listing for pinging.

Thanks to all for the advice.

GN

But even with discount from Sam's/Costco, 93 octane cost is outrageous. I'd sure love to run regular but don't want to damage my sweet new engine trying it.

Allow me to put in my ass clown persona for your entertainment. Some say this is really just my personality all the time.

This is a silly conversation. If you can’t afford to drive on 93 - sell the car.

5,000 miles per year / 25 mpg = 200 gallons used in your 914 a year.

Let’s say 87 is $4/gallon and 93 is $6/gallon

Are you telling me you can’t afford $400 / year delta in cost between 87 & 93 to avoid damaging your engine? Especially if you recognize that you won’t be able to hear the detonation yourself?


The reality is ethanol is an octane booster. However that ethanol boost is already factored into the rating on the pump. I’ll leave all the other ethanol pro vs con alone.

Likewise I’ll set aside the discussion of what your car really needs.

[Gatornapper]

Thanks Zach - will do!

GN

On my 2056 with a torquie cam and mild compression bump (8.6:1) I was able to run 87 and flog the crap out of the motor without it pinging. This was using Microsquirt EFI not carbs or stock injection.

Start with 87. Drive the car and see what it does. If it pings (it probably won’t) go to 89 (you won’t need to).

Zach

[930cabman]

I built a 2056 with AA P&C's a couple years ago with mild cam, Weber 40IDF's and setup the CR at 8.7.

For 55 years I have always run my sporting machines on the best pump gas available.

These days I have been using Sunoco premium because we have Sunoco credit cards.

Never heard a ping and runs great

I too am well off, but still a CSOB

[technicalninja]

If you insist on running reg and you don't have a knock sensor another option is "det cans"
This is basically mounting a microphone to the block and listening...

Doesn't work as well as a dedicated knock sensor but is FAR better than just using your ears (you're still using your ears, the noise is amplified).

Even with all the modern shit det cans are helpful.

If you're smart you run the signal into the "aux in" on a modern head unit/radio and you can listen to ANY noise the engine is making over your amplified sound system. Sometimes the noises are not the right amplitude to set the knock sensor off and you can hear that crap over the "cans".
A bad belt tensioner will make lots of noise but won't set a knock sensor off.
You WILL hear that over the cans.

Google "det cans" if that interests you.
Lots of videos where folks are making det cans for under $50...

Now, air cooled engines are nosier than water cooled. I've not use det cans on air cooled yet.
Might be harder to isolate noises on an air cooled.

Install det cans and want to know what real knock sounds like?
Tap the engine block with a hammer!
It's super close.
Need to test the knock sensor circuit on a modern car. Smack the engine with a hammer. It should stumble as the ECU cuts timing, and you should get a check engine light with a knock sensor code if things are working properly.

This can lead to fraud!
Hyundia had trouble with the 2.0 and 2.4 Gemma motors. Extended engine warranty to 120K for knock issues.
A knock code in the ECU got a brand-new engine installed...

I can create knock codes on command! (IMG:style_emoticons/default/ninja.gif)

[flipb]

I did a rebuild about eight years ago to 2056 with 40 IDF carbs. [edit: With mild cam from European Motorworks.] Recently added the 123 Distributor with up to 30 degrees advance (Bosch 050 mimic).

Like GN's experience, I'm getting power/torque better than my expectations, by seat-of-the-pants-meter. But I'm jealous of his carb settings... I still get lots of popping at partial throttle and an occasional stumble or lumpy idle. And poor mpg.

For what it's worth, my mechanic said to run 93 octane for a while after the rebuild and I've never gone back to 87. Will occasionally run 89 but usually look for 91 or 93. There's no ethanol-free gas near me, so I add an ethanol treatment at each refill. But even during driving season, I'm usually filling the tank less than once a month so the economic impact is minimal.