Hello everyone.
I am increasing compression ratio by installing K20A3 pistons in a F23A1 [9.3:1 to 11:1], according to my research and very helpful responses from members of this forum the only problem could be "knocking". That can be solved by tuning ECU backing off ignition timing, but that is not an option for me now.
My firs propose was to "under-calibrate" TPS sensor, that way is supposed that ECU would inject less fuel than required on normal conditions (increased cr requiress less fuel due to it's improved brake thermal effi-ciency). That apparently was not a solution.

I also must say that as higher is the octane rating of fuel is less likely this unwanted detonation to occurs. So I am trying to figure it out by focus in increasing fuel's octane rating, for that I have found two viable options.

1) Dual fuel engine (Gasoline + HHO Gas)
HHO Gas is a system that powered by the alternator generates Hydrogen from only distilled water and injects this hydrogen thru intake system (Requires more stuff like cells and others but seems to be not that difficult to instal), besides that HHO Gas claims to increase fuel economy by at least 30% and increase power by 10%.
Now the part we need of HHO:
“Introducing HHO gas to the fuel/air mixture has a positive impact on the octane rating of gasoline fuel. Therefore the engine compression ratio can be raised and more gain in the efficiency can be obtained. In addition the ignition advance could be increased to maximize the engine torque without knocking of engine.”

2) Alternative Fuel Engine (LPG | Gasoline [only one at a time])
LPG is an alternative fuel for vehicles with a combustion engine, is also known as Propane Autogas, propane has a higher octane rating than gasoline.
“As compression ratio increases, brake thermal effi-ciency increases. LPG has a higher octane rating and hence the engine can run effectively at relatively high compression ratios without knock”
Here in my country, LPG has become very popular due to it’s economy (Gasoline is expensive), LPG costs are 45% less than gasoline, that is why many Uber drivers and Taxis install LPG.

That makes me think LPG would be a good Idea for my increased cr F23 build.

My build will be for now:
F23Rebuild with all stock + H22 transmission + stock ECU + K20A3 pistons + H beam connecting rods

Any opinion is welcome
If someone has done any of this before for the porpuse I am looking please contact me

Some sources:
https://www.sciencedirect.com/scienc...10016815001714
https://citeseerx.ist.psu.edu/viewdo...=rep1&type=pdf

 

Youre willing to convert to LPG but not willing to chip the ECU?

The easy solution is water injection.
https://www.rbracing-rsr.com/downloads/NACA_H2O_2.pdf

But seriously... just tune the ECU. Or leave it stock.

 

It is because here would be difficult to find a good tunner, I have heard of one but is crazy expensive besides I would have to find ECU and convert to OBD1 that Emmissions trouble.
LPG here is very popular and not that expensive + I have a friend who could sell me all parts needed for good price, and there is a LPG reputable shop with easy access.

Thanks, you think is too risky A3 pistons without tunned ECU?
Even if I do not rev it too much, (Like always under 5000 rpm), I can think about ECU a few months later..

 

Any 'alternative' fuel you can come up with will require tuning, so you won't be getting around it by switching fuels. Your money would be far better invested by converting an ecu and learning to tune yourself and renting dyno time once you are comfortable. An NA engine is very forgiving to learn on and you'd have trouble blowing it up even if you tried. I know tuners need jobs too, but doing it yourself is kind of the whole point of having a hobby, no?

I don't know what your gasoline/petrol quality is like wherever you are, but in the US 11:1 on a port injection engine with pump gas is still doable in most states - Although becoming less so all the time as gasoline quality continues to decline. It really depends on cam choice at that compression ratio. Stock cams with less overlap will have a lower knock limit than high overlap/late intake valve closing aftermarket cams.

E85 is a decent option in the US. Easy to attain in many regions, consistent enough for most users. Terrible for the environment and the economy, but that's a USA problem. If you have it or something similar wherever you are and high octane petrol is not an option, it's worth looking into. You'll still have to tune.

Water injection is a poor choice for controlling knock in an NA engine. The presence of water in the charge always decreases volumetric efficiency more than you will ever get back via increased knock margin. It's barely a good choice for boosted engines either, the only reason it works there is because sometimes you can add more volumetric efficiency by increasing boost than you lost with the water - But not always. Of course, you'll still have to tune. There's no way around it.

The vast majority of 90s/00s Honda engine NA builds that aren't trying to run silly compression on pump gas are not knock limited anyway. Generally, if it's NA and knocking you probably blew past MBT and aren't making full power.

 

spAdam thank you for your input
You think that 11:1 cr for my F23A1 is or is not silly?
What MBT means?

This guy has done it F23A7 which apparently is equal to F23A1
He installed K20A3 pistons in that F23A7 all stock...

Best gasoline here is minimal RON:95,0 minimal MON:83,0
For USA would be the same as 89 octane (95+83 /2)
I have access to STP Octane Booster and LIQUI MOLY 8355 Octane boost

Also I have a really viable option to install LPG system which I understand is like 100 Octane

 

This.

You seem to be ignoring everyone telling you there's no way around this. I also have no idea how something like LPG would impact combustion temperatures, or more importantly how it would behave with a factory fuel pump, lines, injectors, etc.

There's a massive amount of variables you seem to have not even thought about.

Tuning is not an option.

 

You are right!
I realized since I am not able to tune, I will be going with all stock rebuilding F23 parts including pistons.
Thanks to all that gave their two cents. At least I learned a bit.

 

Strongly disagree with you there. Only a tiny bit of water is necessary to have strong a anti-knock effect. Any difference in VE from the displacement of the water should be negligible, and it normally will increase VE by reducing the charge temperature through vaporization of the water. On a forced induction engine you can gain significant power simply be advancing to MBT, no additional boost needed.

I have also seen it used successfully on NA engines for the same reason. The gains would not be as dramatic since the timing is usually not knock limited by as much.
Pat Primmer had a super high compression aircooled VW that made good power on pump gas with water injection.