compression ratio

[AJPG]

Originally Posted by CSG Mike

450whp won't last forever, no matter how good your tune.

The only way the car will last for ever is not using it.

[Tcoat]

Originally Posted by AJPG

The only way the car will last for ever is not using it.

Actually that will ruin it even faster!

[AJPG]

Originally Posted by Tcoat

Actually that will ruin it even faster!

Hahaha! Not exactly what I have in mind.

[AJPG]

Originally Posted by wparsons

Any CARB legal supercharger kits/tunes don't need lower C/R, and doing so will just cost you power.

Sir your statement is true but your didn't answer. It will continue to be carb until you adjust the tune.

[AJPG]

Originally Posted by SPCorBUST

I won't be running a CARB tune, I'll be running a custom tune. I am up for changing CR if it makes the engine more reliable so long as there are no adverse affects to emissions when ON a CARB tune, which would only be used during emissions testing.

Heat that's the enemy, you have to keep fluids in operating temps at all times if you really desire the car to last. But I can't help more due to tha lack of info about your car and goal... A good tune could help a lot, but is only part of the equation.

[Jaden]

Originally Posted by SPCorBUST

Does anyone know how lower compression pistons affect emissions? I think I'd like to use lower compression pistons but I'm concerned that I'll no longer be able to pass a smog. California CARB is a PITA.

You should be more worried about what F/I solution you'll be using than what compression ratio you're running..

Also, I believe that our cars won't have a sniffer test when they start getting tested, so you would only need to pass the OBD-II test and the visual inspection.

If you plan on using a non CARBed turbo or other F/I solution, you'll have to remove it for inspection, which means you'll have to change the tune.

With lower compression, you'll just have a different tune that makes less power, but if the tune is right it should still pass.

Jaden

[wparsons]

Originally Posted by AJPG

Sir your statement is true but your didn't answer. It will continue to be carb until you adjust the tune.

No. Modifying the engine internals (unless the new internals also have a CARB approval) will make it not CARB legal.

It'll also run way less than ideally on a lower c/r on the tune meant for stock c/r.

[AJPG]

Originally Posted by wparsons

No. Modifying the engine internals (unless the new internals also have a CARB approval) will make it not CARB legal.

It'll also run way less than ideally on a lower c/r on the tune meant for stock c/r.

Nop.

[AJPG]

Originally Posted by Jaden

You should be more worried about what F/I solution you'll be using than what compression ratio you're running..

Also, I believe that our cars won't have a sniffer test when they start getting tested, so you would only need to pass the OBD-II test and the visual inspection.

If you plan on using a non CARBed turbo or other F/I solution, you'll have to remove it for inspection, which means you'll have to change the tune.

With lower compression, you'll just have a different tune that makes less power, but if the tune is right it should still pass.

Jaden

Agree, but to clarify.

The only thing that you should do different on tune with same everything except from cr, is timing, no need to touch fuel.

[wparsons]

Originally Posted by AJPG

The only thing that you should do different on tune with same everything except from cr, is timing, no need to touch fuel.

You'll never tune my car, that's for sure

If you think the only thing you'd need to change after dropping the C/R like 3 full points is timing, you're in for a world of pain.

That much of a change is going to drastically alter the volumetric efficiency of the engine, and would require a full re-tune.

[AJPG]

Originally Posted by wparsons

You'll never tune my car, that's for sure

If you think the only thing you'd need to change after dropping the C/R like 3 full points is timing, you're in for a world of pain.

That much of a change is going to drastically alter the volumetric efficiency of the engine, and would require a full re-tune.

Sir today is your lucky day!

I am not a tuner (not professional and the ones I have done were finish by real professional tuner).

But what is volumetric efficiency? How can it be changed or altered?

Volumetric efficiency, is the amount air (CFM) that gets to the "air chamber" to be used to produce the controlled explosion...
So it could be altered with modifications to the intake, heads (port, valves # and size) cams (duration and lift) exhaust, also and more dramatic with FI but no with cr. Sorry.