hi was curious to how high compression pistons actually create more power for our tibs or any car for that matter. Lets use an example of putting in high compression pistons at 13.0:1 at 83mm on our tib with the basic bolt ons and tuned. How much would they gain us by adding the pistons and how does that power come about?

 

Well first of all, the 83mm are larger than stock...so right there you're basically going to make your engine have a higher capacity than the 2.0L (or 1.8L depending of which engine you have) in your cylinders.

 

I don't have any experience on Beta engines, but for what I have seen in other cars (some Toyota and Peugeot engines) each whole point you add of compression adds A LOT of power for a NA car. And I mean a lot. Jumping from our OEM 10,1:1 baseline to 11,5:1 would be a great deal, now 13:1 is a BIG deal for compression. It's really impossible to figure out how much power you will be doing, and also, if you are tearing your engine apart for piston change, it would be nonsense to not add other things, I would think about pistons after:
-CAI
-Headers & Full exhaust
-1.8 Beta Intake Cam (if you can add another cam, such as the REAL Ecu-Cam combo, much better)
-AirRam

Then your 13:1 pistons would give out their best, but I guess you will have to run on 110 octane fuel as a daily basis, I don't think you can manage to go with 13:1 compression even on the highest grade "normal" gas.
However, you can install the pistons first if you want, and then add the other mods as they are bolt ons only, but it's the combo of that what will take you up on the power range.

They should raise your power AND torque curves, and they definitely will need ECU upgrade (and I don't think just a piggyback could do it because it's not a matter of altering fuel curves, but ignition timing).

 

having a close to perfect compression ratio for combustion of fuel is what gives you the best power output, exactly how much power depends on each setup


So far as what octane to run, how do you calculate that?
I was under the impression that if your car was pre-detonating(pinging) from an incorrect octane after upping the compression ratio, that you could retard your ignition timing... how far out am I on this?


And whats that about piggyback chips? wink1.gif
Taken from this link:
"Every engine requires optimum ignition timing and air fuel ratio at all RPM and load conditions. UniChip provides access and ability to adjust and optimize both the ignition and fuel system. UniChip has seventeen RPM sites between 500 RPM and 8000 RPM and twelve load sites between zero throttle position and wide-open throttle position. This equates to 204 possible adjustments for fuel and a further 204 adjustments for ignition timing."

 

[/quote]if you can add another cam, such as the REAL Ecu-Cam combo, much better[quote]


What does this mean?

 

hes talking about getting a performance intake and exhaust cam, and then as for the "real ecu-cam combo" bit, "real" is a company, and they make a reflashed ecu and performance camshaft combination for a good tune with the new cams.

 

TK Error Tib, you choose a really old post to arise! lmao.gif This is almost exactly a one year old post!
The Real combo was being offered here, BEFORE "Real" went out of business in a sad way.
However, I was talking about a performance camshaft, that would require no matter what ECU modifications or even a new custom-programed ECU.

Compression increase shouldn't alter the air/fuel ratio, because in admission the amount of air that goes into the cylinder is the same, it's how much you compress that air what gives you a power differential, so the air/fuel ratio is not altered, but the dynamics of the air within the combustion chamber could be altered, and of course the fact that at higher compression air-fuel mix tends to self detonate... so you would have to use higher grade fuel to prevent detonation and maybe (specially if you raise compression too much, like to 12+:1) retard ignition timing. There is no way to program ignition timing for our cars without changing either the ECU or the ECU programing; I am not too versed on that matter, but I know there are not too many options, search for ECU and you will find a lot of info.

 

actually, the car should require a bit more fuel, just to keep from running lean.

Personally, I would never run 13 to 1 ratio on the street. BMW only runs an 11 to 1 on their new direct injection engines.. and they can get away with that because the fuel is directly injected into the combustion chamber (instead of in the intake runner) where it can cool the charge some and keep the engine from detonation.

But you are correct in the other ways. Higher compression does mean more power. I cannot give you a definite answer how much, as other factors get in the way.