Highest compression ratio

[Turpro]

Couple questions for the gods

What's the highest comp ratio you can run on a bp without having to go stand alone?

What exactly is the standalone adjusting when using it for high comp? Is it used for fuel/air? Spark? Would a safc help the same way for high comp?

Was thinking of building a solid dd high comp bp. 11:1 tops,exintake cam swap,14-16* timing,headers,exaust.

[therieldeal]

changing compression ratio changes the volumetric efficiency of the engine, so the optimum timing and fuel maps are going to shift compared to what is contained in the stock computer. how far off it would be is kind of impossible to say

[Turpro]

So a safc would help with the fuel aspect part? Then there's the whole timing part.

[therieldeal]

a safc sort of helps with fuel but as you "adjust the fuel" you are really telling the ECU that the load is higher or lower than it really is... which ends up (unpredictably) changing the timing as well.

[mx-3_4evr]

minnesotapj is running 11:1 on his protege with stock ECU. You might want to send him a PM

[Turpro]

minnesotapj is running 11:1 on his protege with stock ECU. You might want to send him a PM

Orly? Might have to shoot that pm. Thanks

[Lex]

There is a difference between an engine running and an engine running efficiently. Of course achieving best efficiency requires lots of time and money(instrumentation) investment.

[MD323]

I love how people are like "such and who is running barnyard hooch in his gas on a stock ecu and 32.6863 PSI on a stock motor! That means its good!"

If that was the case, then everyone needs to go ride dirtbikes drunk and do dumbstuff in the wood miles away from a hospital. I've done it since I was 14 and I never broke a bone or died so you will be fine, now go have fun!

[Justbp-me]

I love how people are like "such and who is running barnyard hooch in his gas on a stock ecu and 32.6863 PSI on a stock motor! That means its good!"

If that was the case, then everyone needs to go ride dirtbikes drunk and do dumbstuff in the wood miles away from a hospital. I've done it since I was 14 and I never broke a bone or died so you will be fine, now go have fun!

laawl

[Turpro]

So what are you trying to say Shawn? You trying to say "run 13:1 and 40psi"? Ok. Give me a few weeks I'll let ya know how that goes lol


On a serious note....would 10:1 be the most you'd want to run on an/a ecu? What about on a boosted motor? 10:1 be too much running on a gtx setup?

[MD323]

N/A I'd run 93 on 10:1 and nothing more that 14 deg without a standalone, even then I'd spend some time on the dyno and make sure its all good and your plugs look good.

[mx-3_4evr]

10:1 cast pistons will not hold boost, maybe @ like 3-5psi. Ok before I dig deeper, are you going N/A or turbo?

[Turpro]

10:1 cast pistons will not hold boost, maybe @ like 3-5psi. Ok before I dig deeper, are you going N/A or turbo?

Well right now I'm selling off the turbo parts(anyoen want info on what's avalible PM me ) because I need the money for family things. I'm going to rebuild the bp that's sitting in the garage in the meantime. I know a stock bp will feel hella slower than the baby turbo setup I have now so I figured give it a little bump in comp to give a little more power(I'd only run miata oem pistons). So when the time comes(1-2 yrs) I'm going to boost again but then I'd have to figure out if I need to rebuild another motor or can boost on the 10:1 pistons. It would be a little beter than stock gtx setup. On a n/a bp it would give around 225-250whp when done. So maybe I just answered my own question lol

[mx-3_4evr]

I will go with the 9:1 pistons since you will be boosting it later. You will still have some N/A power. It will just benefit you better on the end. And make sure you get some rods.

[323driver]

Stock BP is 8.8:1 so what's the point going 9:1? It's either high comp NA or normal comp boosted, can't have both, unless you are willing to spend on some fancy control systems, tuning, standalone etc etc. With money, everything is possible...