higher compression pistons....good?

[savvy]

hey yall was looking up on ktec and saw the high 12:1 compression forged pistons neone here run these on their rides? is it any good what kinda power figures gained? i love natural aspiration but this is still sort of a shady area for me so im willing to learn something, and what kind of octane rating gas must u have to use to maintain efficiency in trini we have 92 and 91 is this safe if someone were to install the high 12:1 comp pistons from ktec ne light on the matter would help
bless

 

[GordonD]

12:1 pistons? Wouldn't be a bad idea if you were converting to LPG.

It'd be a pretty expensive modification with a poor payoff in terms of increased power and torque for an ordinary road car. Its the sort of thing you'd include if you were going to build a rally car and you werre going to run it on 100 octane.

 

[edde]

You should be fine on 95 ron but you need to talk to someone like BenR oe stan* about it it will depends what other bits and pieces your engine going to have.

I think some of the highty tunned N/A cars on the site ie Yozzasports and the two throttle bodies one can still run finr on 95ron even with the high compression pistons it just ups the EGR and thats what you have to be careful off.

There more yyou ned to invest in to get decinet power before pushing for pistons normal tunning will get you to about 230hp without going to change bits like this. WItout either a massivly reworked manafold or throttle bodies ithere no point that I can see.

 

[16v_jon]

what you need to think of is does you engine have the breathing mods or cam profile to take advantage of the higher compression piston?

 

[savvy]

nice infor guys, thanks cleared up some misperceptions in this case i would presume for the geographic and demographic region in which i live in a turbo kit would be most viable. however kinda of expensive but thats the price u pay for speed and reliability and also quality heh, but is there any ways to just add a little more peppyness to the 172 without going to deeply into the cash pocket not looking at big figures but has neone ever lightened the flywheel for increased accel in these cars, or stronger clutch and pressure plate those kind of mods,

basically what im asking is what can be done to increase accel without going to high into the power echelon band
thanks

 

[edde]

nice infor guys, thanks cleared up some misperceptions in this case i would presume for the geographic and demographic region in which i live in a turbo kit would be most viable. however kinda of expensive but thats the price u pay for speed and reliability and also quality heh, but is there any ways to just add a little more peppyness to the 172 without going to deeply into the cash pocket not looking at big figures but has neone ever lightened the flywheel for increased accel in these cars, or stronger clutch and pressure plate those kind of mods,

basically what im asking is what can be done to increase accel without going to high into the power echelon band
thanks

Decat and manifold reworking work are the best value then 182 exhaust manifold

 

[Chris_H]

high cr is always a benefit. Higher the CR the higher the thermal efficiency, thus power, torque and economy increase.

It will be fine on 95 ron as long as its mapped properly.

High cr engines do wear faster though theres no argument, wear however is like it will do 250k insteads of 280k. Its nto gonan die within 6 months unless your a pillock.

 

[stan*]

Higher combustion efficiency Chris.

Thermal efficiency actually starts to deteriorate when you get past C13:1 as the volume:surface-area ratio of the chamber reduces.

 

[Fred@BTM]

we run high comp pistons in ours, i wouldn't install them in a road car thats used everyday

if the k-tec ones are the ones i think they are, they're not a genuine 12:1, but i maybe wrong

 

[savvy]

kool interesting my car has a decat already im running a straight exhaust and some thermal coating on the intake pipe, it might not do much but still repels engine heat its a little more torque but nuttin wowish, if i get enough information might lighten up the flywheel whats the views on doing such?

 

[Fred@BTM]

lightened flywheel works well, although its pretty good standard

 

[GordonD]

high cr is always a benefit. Higher the CR the higher the thermal efficiency, thus power, torque and economy increase.

It will be fine on 95 ron as long as its mapped properly.

If a high CR is always better, and its just a matter of mapping it "properly", why do Clio sports "only" run 11.2:1? Why don't they run 12 to one standard? 13? 14? 15? 16? And why do most cars run far lower CRs?

The answer is that its not just a matter of mapping it "properly". For any given engine design - materials, combustion chamber shape, etc - there's a limit to how high a CR you can go to with any given octane of fuel before it thinks its a diesel. And even below that you may not get the power increases that theory says you should get because you have to use non-optimum ignition timing to stop it pre-igniting. I'd suggest that Renault's engineers looked at those factors when they decided that 11.2:1 was the best number for an engine that was going to run on pump gas. That was as high as they could go before they had to back off the ignition so much that that was losing more power than it was gaining in thermal efficiency.

 

[stan*]

Yup, too much retarding from MBT timing figure is just going to be crap for performance. Also over compressing an engine is going to increase mechanical losses.

Also, mass produced engines are intended to run in most conditions, including extremes. An engine running a given high Cr may run without risk of detonation in say the uk...but take it to higher ambient temps, and intake temps increase=det blah blah. Same with fuel qualities really.

 

[savvy]

true and in trinidad stan temperatures will frig over that high compression and also we do not have the proper octance rating gas to fuel a car as such with high cr, sadly its true so it will most likely end up in explosion down here but turbo is always a welcome hehe but i dont think i need that right now